| 1. |
- Permyakov, Sergei E, et al.
(författare)
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Oleic acid is a key cytotoxic component of HAMLET-like complexes
- 2012
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Ingår i: Biological Chemistry. - 1437-4315. ; 393:1-2, s. 85-92
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Tidskriftsartikel (refereegranskat)abstract
- HAMLET is a complex of α-lactalbumin (α-LA) with oleic acid (OA) that selectively kills tumor cells and Streptococcus pneumoniae. To assess the contribution of the proteinaceous component to cytotoxicity of HAMLET, OA complexes with proteins structurally and functionally distinct from α-LA were prepared. Similar to HAMLET, the OA complexes with bovine β-lactoglobulin (bLG) and pike parvalbumin (pPA) (bLG-OA-45 and pPA-OA-45, respectively) induced S. pneumoniae D39 cell death. The activation mechanisms of S. pneumoniae death for these complexes were analogous to those for HAMLET, and the cytotoxicity of the complexes increased with OA content in the preparations. The half-maximal inhibitory concentration for HEp-2 cells linearly decreased with rise in OA content in the preparations, and OA concentration in the preparations causing HEp-2 cell death was close to the cytotoxicity of OA alone. Hence, the cytotoxic action of these complexes against HEp-2 cells is induced mostly by OA. Thermal stabilization of bLG upon association with OA implies that cytotoxicity of bLG-OA-45 complex cannot be ascribed to molten globule-like conformation of the protein component. Overall, the proteinaceous component of HAMLET-like complexes studied is not a prerequisite for their activity; the cytotoxicity of these complexes is mostly due to the action of OA.
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| 2. |
- Roche-Hakansson, Hazeline, et al.
(författare)
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The human milk protein-lipid complex HAMLET disrupts glycolysis and induces death in Streptococcus pneumoniae
- 2019
-
Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 294:51, s. 19511-19522
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Tidskriftsartikel (refereegranskat)abstract
- HAMLET is a complex of human a-lactalbumin (ALA) and oleic acid and kills several Gram-positive bacteria by a mechanism that bears resemblance to apoptosis in eukaryotic cells. To identify HAMLET's bacterial targets, here we used Streptococcus pneumoniae as a model organism and employed a proteomic approach that identified several potential candidates. Two of these targets were the glycolytic enzymes fructose bis-phosphate aldolase (FBPA) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Treatment of pneumococci with HAMLET immediately inhibited their ATP and lactate production, suggesting that HAMLET inhibits glycolysis. This observation was supported by experiments with recombinant bacterial enzymes, along with biochemical and bacterial viability assays, indicating that HAMLET's activity is partially inhibited by high glucose-mediated stimulation of glycolysis but enhanced in the presence of the glycolysis inhibitor 2-deoxyglucose. Both HAMLET and ALA bound directly to each glycolytic enzyme in solution and solid phase assays and effectively inhibited their enzymatic activities. In contrast, oleic acid alone had little to no inhibitory activity. However, ALA alone also exhibited no bactericidal activity and did not block glycolysis in whole cells, suggesting a role for the lipid moiety in the internalization of HAMLET into the bacterial cells to reach its target(s). This was verified by inhibition of enzyme activity in whole cells after HAMLET but not ALA exposure. The results of this study suggest that part of HAMLET's antibacterial activity relates to its ability to target and inhibit glycolytic enzymes, providing an example of a natural antimicrobial agent that specifically targets glycolysis.
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| 3. |
- Tyx, Robert E, et al.
(författare)
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Role of dihydrolipoamide dehydrogenase in regulation of raffinose transport in Streptococcus pneumoniae
- 2011
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Ingår i: Journal of Bacteriology. - 0021-9193. ; 193:14, s. 24-3512
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pneumoniae strains lacking the enzyme dihydrolipoamide dehydrogenase (DLDH) show markedly reduced ability to grow on raffinose and stachyose as sole carbon sources. Import of these sugars occurs through the previously characterized raffinose ATP-binding cassette (ABC) transport system, encoded by the raf operon, that lacks the necessary ATP-binding protein. In this study, we identified the raffinose ATP-binding protein RafK and showed that it was directly involved in raffinose and stachyose import. RafK carries a C-terminal regulatory domain present in a subset of ATP-binding proteins that has been involved in both direct regulation of transporter activity (inducer exclusion) and transcription of transporter genes. Pneumococci lacking RafK showed a 50- to 80-fold reduction in expression of the raf operon genes aga (alpha-galactosidase) and rafEFG (raffinose substrate binding and permease genes), and both glucose and sucrose inhibited raffinose uptake through inducer exclusion. Like RafK, the presence of DLDH also activated the expression of raf operon genes, as DLDH-negative pneumococci showed a significantly decreased expression of aga and rafEFG, but DLDH did not regulate rafK or the putative regulatory genes rafR and rafS. DLDH also bound directly to RafK both in vitro and in vivo, indicating the possibility that DLDH regulates raffinose transport by a direct interaction with the regulatory domain of the transporter. Finally, although not as attenuated as DLDH-negative bacteria, pneumococci lacking RafK were significantly outcompeted by wild-type bacteria in colonization experiments of murine lung and nasopharynx, indicating a role for raffinose and stachyose transport in vivo.
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| 4. |
- Alamiri, Feiruz, et al.
(författare)
-
A role of epithelial cells and virulence factors in biofilm formation by Streptococcus pyogenes in vitro
- 2020
-
Ingår i: Infection and Immunity. - 1098-5522. ; 88:10
-
Tidskriftsartikel (refereegranskat)abstract
- Biofilm formation by Streptococcus pyogenes (GAS) in model systems mimicking the respiratory tract is poorly documented. Most studies have been conducted on abiotic surfaces, which poorly represent human tissues. We have previously shown that GAS forms mature and antibiotic-resistant biofilms on physiologically relevant epithelial cells. However, the role of the substratum, extracellular matrix (ECM) components, or GAS virulence factors for biofilm formation and structure is unclear. In this study, biofilm formation was measured on respiratory epithelial cells and keratinocytes by determining biomass and antibiotic resistance, and biofilm morphology was visualized using scanning electron microscopy. All GAS isolates tested formed biofilms that had similar, albeit not identical, biomass and antibiotic resistance for both cell types. Interestingly, functionally mature biofilms formed more rapidly on keratinocytes but were structurally denser and coated with more ECM on respiratory epithelial cells. The ECM was crucial for biofilm integrity, as protein- and DNA-degrading enzymes induced bacterial release from biofilms. Abiotic surfaces supported biofilm formation, but these biofilms were structurally less dense and organized. No major role of M protein, capsule, or Streptolysin O was observed in biofilm formation on epithelial cells, although some morphological differences were detected. NAD-glycohydrolase was required for optimal biofilm formation, whereas Streptolysin S or cysteine protease SpeB impaired this process. Finally, no correlation was found between cell adherence or auto-aggregation and GAS biofilm formation. Combined, these results provide a better understanding of the role of biofilm formation in GAS pathogenesis and can potentially provide novel targets for future treatments against GAS infections.
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| 5. |
- Alamiri, Feiruz, et al.
(författare)
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HAMLET, a protein complex from human milk has bactericidal activity and enhances the activity of antibiotics against pathogenic Streptococci
- 2019
-
Ingår i: Antimicrobial Agents and Chemotherapy. - 1098-6596. ; 63:12
-
Tidskriftsartikel (refereegranskat)abstract
- HAMLET is a protein-lipid complex derived from human milk that was first described for its tumoricidal activity. Later studies showed that HAMLET also has direct bactericidal activity against select species of bacteria, with highest activity against Streptococcus pneumoniae Additionally, HAMLET in combination with various antimicrobial agents can make a broader range of antibiotic-resistant bacterial species sensitive to antibiotics. Here, we show that HAMLET has direct antibacterial activity not only against pneumococci, but also against Streptococcus pyogenes (GAS) and Streptococcus agalactiae (GBS). Analogous to pneumococci, HAMLET-treatment of GAS and GBS resulted in depolarization of the bacterial membrane followed by membrane permeabilization and death that could be inhibited by calcium and sodium transport inhibitors. Treatment of clinical antibiotic-resistant isolates of S. pneumoniae, GAS, and GBS with sublethal concentrations of HAMLET in combination with antibiotics decreased the minimal inhibitory concentrations of the respective antibiotic into the sensitive range. This effect could also be blocked by ion transport inhibitors, suggesting that HAMLET's bactericidal and combination treatment effects used similar mechanisms. Finally, we show that HAMLET potentiated the effects of erythromycin against erythromycin-resistant bacteria more effectively than it potentiated killing by penicillin G of bacteria resistant to penicillin G. These results show for the first time that HAMLET effectively kills three different species of pathogenic Streptococci using similar mechanisms and also potentiate the activity of macrolides and lincosamides more effectively than combination treatment with beta-lactams. These findings suggest a potential therapeutic role for HAMLET in repurposing antibiotics currently causing treatment failures in patients.
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| 6. |
- Alamiri, Feiruz, et al.
(författare)
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Role of serotype and virulence determinants of Streptococcus pyogenes biofilm bacteria in internalization and persistence in epithelial cells in vitro.
- 2023
-
Ingår i: Frontiers in cellular and infection microbiology. - 2235-2988. ; 13
-
Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pyogenes causes a multitude of local and systemic infections, the most common being pharyngitis in children. Recurrent pharyngeal infections are common and are thought to be due to the re-emergence of intracellular GAS upon completion of antibiotic treatment. The role of colonizing biofilm bacteria in this process is not fully clear. Here, live respiratory epithelial cells were inoculated with broth-grown or biofilm bacteria of different M-types, as well as with isogenic mutants lacking common virulence factors. All M-types tested adhered to and were internalized into epithelial cells. Interestingly, internalization and persistence of planktonic bacteria varied significantly between strains, whereas biofilm bacteria were internalized in similar and higher numbers, and all strains persisted beyond 44 hours, showing a more homogenous phenotype. The M3 protein, but not the M1 or M5 proteins, was required for optimal uptake and persistence of both planktonic and biofilm bacteria inside cells. Moreover, the high expression of capsule and SLO inhibited cellular uptake and capsule expression was required for intracellular survival. Streptolysin S was required for optimal uptake and persistence of M3 planktonic bacteria, whereas SpeB improved intracellular survival of biofilm bacteria. Microscopy of internalized bacteria showed that planktonic bacteria were internalized in lower numbers as individual or small clumps of bacteria in the cytoplasm, whereas GAS biofilm bacteria displayed a pattern of perinuclear localization of bacterial aggregates that affected actin structure. Using inhibitors targeting cellular uptake pathways, we confirmed that planktonic GAS mainly uses a clathrin-mediated uptake pathway that also required actin and dynamin. Clathrin was not involved in biofilm internalization, but internalization required actin rearrangement and PI3 kinase activity, possibly suggesting macropinocytosis. Together these results provide a better understanding of the potential mechanisms of uptake and survival of various phenotypes of GAS bacteria relevant for colonization and recurrent infection.
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| 7. |
- Barenkamp, Stephen J., et al.
(författare)
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Panel 4 : Report of the Microbiology Panel
- 2017
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Ingår i: Otolaryngology - Head and Neck Surgery. - : Wiley. - 0194-5998 .- 1097-6817. ; 156:4_suppl, s. 51-62
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To perform a comprehensive review of the literature from July 2011 until June 2015 on the virology and bacteriology of otitis media in children. Data Sources: PubMed database of the National Library of Medicine. Review Methods: Two subpanels comprising experts in the virology and bacteriology of otitis media were created. Each panel reviewed the relevant literature in the fields of virology and bacteriology and generated draft reviews. These initial reviews were distributed to all panel members prior to meeting together at the Post-symposium Research Conference of the 18th International Symposium on Recent Advances in Otitis Media, National Harbor, Maryland, in June 2015. A final draft was created, circulated, and approved by all panel members. Conclusions: Excellent progress has been made in the past 4 years in advancing our understanding of the microbiology of otitis media. Numerous advances were made in basic laboratory studies, in animal models of otitis media, in better understanding the epidemiology of disease, and in clinical practice. Implications for Practice: (1) Many viruses cause acute otitis media without bacterial coinfection, and such cases do not require antibiotic treatment. (2) When respiratory syncytial virus, metapneumovirus, and influenza virus peak in the community, practitioners can expect to see an increase in clinical otitis media cases. (3) Biomarkers that predict which children with upper respiratory tract infections will develop otitis media may be available in the future. (4) Compounds that target newly identified bacterial virulence determinants may be available as future treatment options for children with otitis media.
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| 8. |
- Bergenfelz, Caroline, et al.
(författare)
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Streptococcus pneumoniae Otitis Media Pathogenesis and How It Informs Our Understanding of Vaccine Strategies.
- 2017
-
Ingår i: Current Otorhinolaryngology Report. - : Springer Science and Business Media LLC. - 2167-583X. ; 5:2, s. 115-124
-
Forskningsöversikt (refereegranskat)abstract
- Purpose of Review This study aimed to review the literature regarding the mechanisms of transition from asymptomatic colonization to induction of otitis media and how the insight into the pathogenesis of otitis media has the potential to help design future otitis media-directed vaccines. Recent Findings Respiratory viruses have long been shown to predispose individuals to bacterial respiratory infections, such as otitis media. Recent information suggests that Streptococcus pneumoniae, which colonize the nasopharynx asymptomatical- ly, can sense potentially “threatening” changes in the nasopha- ryngeal environment caused by virus infection by upregulating specific sets of genes involved in biofilm release, dissemination from the nasopharynx to other sites, and protection against the host immune system. Furthermore, an understanding of the transcriptional and proteomic changes occurring in bacteria dur- ing transition to infection has led to identification of novel vaccine targets that are disease-specific and will not affect asymptomatic colonization. This approach will avoid major changes in the delicate balance of microorganisms in the respi- ratory tract microbiome due to elimination of S. pneumoniae. Summary Our recent findings are reviewed in the context of the current literature on the epidemiology and pathogenesis of otitis media. We also discuss how other otopathogens, such as Haemophilus influenzae and Moraxella catarrhalis, as well as the normal respiratory microbiome, can modulate the ability of pneumococci to cause infection. Furthermore, the unsatis- factory protection offered by the pneumococcal conjugate vaccines is highlighted and we review potential future strate- gies emerging to confer a more specific protection against otitis media.
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| 9. |
- Chao, Yashuan, et al.
(författare)
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Growing and Characterizing Biofilms Formed by Streptococcus pneumoniae
- 2019
-
Ingår i: Streptococcus pneumoniae : Methods and Protocols - Methods and Protocols. - New York, NY : Springer New York. - 1940-6029. - 9781493991990 - 9781493991983 ; 1968, s. 147-171
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Bokkapitel (refereegranskat)abstract
- It is estimated that over 80% of bacterial infections are associated with biofilm formation. Biofilms are organized bacterial communities formed on abiotic surfaces, such as implanted or inserted medical devices, or on biological surfaces, such as epithelial linings and mucosal surfaces. Biofilm growth is advantageous for the bacterial organism as it protects the bacteria from antimicrobial host factors and allows the bacteria to reside in the host without causing excessive inflammation. Like many other opportunistic pathogens of the respiratory tract, Streptococcus pneumoniae forms biofilms during asymptomatic carriage, which promotes, among other things, persistence in the niche, intraspecies and interspecies communication, and spread of bacterial DNA. Changes within the colonizing environment resulting from host assaults, such as virus infection, can induce biofilm dispersion where bacteria leave the biofilm and disseminate to other sites with ensuing infection. In this chapter, we present methodology to form complex biofilms in the nasopharynx of mice and to evaluate the biofilm structure and function in this environment. Furthermore, we present methods that recapitulate this biofilm phenotype in vitro by incorporating crucial factors associated with the host environment and describe how these models can be used to study biofilm function, transformation, and dispersion.
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| 10. |
- Chao, Yashuan, et al.
(författare)
-
Streptococcus pneumoniae biofilm formation and dispersion during colonization and disease.
- 2015
-
Ingår i: Frontiers in cellular and infection microbiology. - : Frontiers Media SA. - 2235-2988. ; 4
-
Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pneumoniae (the pneumococcus) is a common colonizer of the human nasopharynx. Despite a low rate of invasive disease, the high prevalence of colonization results in millions of infections and over one million deaths per year, mostly in individuals under the age of 5 and the elderly. Colonizing pneumococci form well-organized biofilm communities in the nasopharyngeal environment, but the specific role of biofilms and their interaction with the host during colonization and disease is not yet clear. Pneumococci in biofilms are highly resistant to antimicrobial agents and this phenotype can be recapitulated when pneumococci are grown on respiratory epithelial cells under conditions found in the nasopharyngeal environment. Pneumococcal biofilms display lower levels of virulence in vivo and provide an optimal environment for increased genetic exchange both in vitro and in vivo, with increased natural transformation seen during co-colonization with multiple strains. Biofilms have also been detected on mucosal surfaces during pneumonia and middle ear infection, although the role of these biofilms in the disease process is debated. Recent studies have shown that changes in the nasopharyngeal environment caused by concomitant virus infection, changes in the microflora, inflammation, or other host assaults trigger active release of pneumococci from biofilms. These dispersed bacteria have distinct phenotypic properties and transcriptional profiles different from both biofilm and broth-grown, planktonic bacteria, resulting in a significantly increased virulence in vivo. In this review we discuss the properties of pneumococcal biofilms, the role of biofilm formation during pneumococcal colonization, including their propensity for increased ability to exchange genetic material, as well as mechanisms involved in transition from asymptomatic biofilm colonization to dissemination and disease of otherwise sterile sites. Greater understanding of pneumococcal biofilm formation and dispersion will elucidate novel avenues to interfere with the spread of antibiotic resistance and vaccine escape, as well as novel strategies to target the mechanisms involved in induction of pneumococcal disease.
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| 11. |
- Chao, Yashuan, et al.
(författare)
-
The serine protease HtrA plays a key role in heat-induced dispersal of pneumococcal biofilms
- 2020
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pneumoniae (the pneumococcus) colonizes the human nasopharynx by forming multicellular biofilms. Due to the high level of asymptomatic carriage, transition to infections, such as otitis media, pneumonia, sepsis, and meningitis, occurs often enough that the pneumococcus remains a major cause of disease and death globally. Virus infection and virus-induced responses, such as increased temperature (fever), trigger release of virulent bacteria from colonizing biofilms. The exact mechanisms involved in pneumococcal egress during biofilm dispersal remain unknown, although we hypothesize that disruption of the biofilm matrix encasing the bacteria is necessary. Here, we utilized established in vitro biofilm dispersal models to investigate the involvement of proteases in bacterial egress from pneumococcal biofilms. We demonstrate the importance of protease activity, both through increased bacterial release following addition of proteases and reduced heat-induced biofilm dispersal in the presence of protease inhibitors. We identify a key role for the surface-exposed serine protease HtrA, but not PrtA, in heat-induced biofilm dispersal. Bacterial release from htrA-negative biofilms was significantly reduced compared to wild-type isogenic strains but was restored and increased above wild-type levels following addition of recombinant HtrA. Understanding the specific mechanisms involved in bacterial egress may provide novel targets for future strategies aimed to specifically interfere with disease progression without disturbing nasopharyngeal biofilm colonization.
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| 12. |
- Clementi, Emily A., et al.
(författare)
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A Complex of Equine Lysozyme and Oleic Acid with Bactericidal Activity against Streptococcus pneumoniae
- 2013
-
Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 8:11, s. Article Number: UNSP e80649-
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Tidskriftsartikel (refereegranskat)abstract
- HAMLET and ELOA are complexes consisting of oleic acid and two homologous, yet functionally different, proteins with cytotoxic activities against mammalian cells, with HAMLET showing higher tumor cells specificity, possibly due to the difference in propensity for oleic acid binding, as HAMLET binds 5-8 oleic acid molecules per protein molecule and ELOA binds 11-48 oleic acids. HAMLET has been shown to possess bactericidal activity against a number of bacterial species, particularly those with a respiratory tropism, with Streptococcus pneumoniae displaying the greatest degree of sensitivity. We show here that ELOA also displays bactericidal activity against pneumococci, which at lower concentrations shows mechanistic similarities to HAMLET's bactericidal activity. ELOA binds to S. pneumoniae and causes perturbations of the plasma membrane, including depolarization and subsequent rupture, and activates an influx of calcium into the cells. Selective inhibition of calcium channels and sodium/calcium exchange activity significantly diminished ELOA's bactericidal activity, similar to what we have observed with HAMLET. Finally, ELOA-induced death was also accompanied by DNA fragmentation into high molecular weight fragments - an apoptosis-like morphological phenotype that is seen during HAMLET-induced death. Thus, in contrast to different mechanisms of eukaryote cell death induced by ELOA and HAMLET, these complexes are characterized by rather similar activities towards bacteria. Although the majority of these events could be mimicked using oleic acid alone, the concentrations of oleic acid required were significantly higher than those present in the ELOA complex, and for some assays, the results were not identical between oleic acid alone and the ELOA complex. This indicates that the lipid, as a common denominator in both complexes, is an important component for the complexes' bactericidal activities, while the proteins are required both to solubilize and/or present the lipid at the bacterial membrane and likely to confer other and separate functions during the bacterial death.
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| 13. |
- Clementi, Emily A, et al.
(författare)
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A novel initiation mechanism of death in Streptococcus pneumoniae induced by the human milk protein-lipid complex HAMLET and activated during physiological death
- 2012
-
Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 287:32, s. 82-27168
-
Tidskriftsartikel (refereegranskat)abstract
- To cause colonization or infection, most bacteria grow in biofilms where differentiation and death of subpopulations is critical for optimal survival of the whole population. However, little is known about initiation of bacterial death under physiological conditions. Membrane depolarization has been suggested, but never shown to be involved, due to the difficulty of performing such studies in bacteria and the paucity of information that exists regarding ion transport mechanisms in prokaryotes. In this study, we performed the first extensive investigation of ion transport and membrane depolarization in a bacterial system. We found that HAMLET, a human milk protein-lipid complex, kills Streptococcus pneumoniae (the pneumococcus) in a manner that shares features with activation of physiological death from starvation. Addition of HAMLET to pneumococci dissipated membrane polarity, but depolarization per se was not enough to trigger death. Rather, both HAMLET- and starvation-induced death of pneumococci specifically required a sodium-dependent calcium influx, as shown using calcium and sodium transport inhibitors. This mechanism was verified under low sodium conditions, and in the presence of ionomycin or monensin, which enhanced pneumococcal sensitivity to HAMLET- and starvation-induced death. Pneumococcal death was also inhibited by kinase inhibitors, and indicated the involvement of Ser/Thr kinases in these processes. The importance of this activation mechanism was made evident, as dysregulation and manipulation of physiological death was detrimental to biofilm formation, a hallmark of bacterial colonization. Overall, our findings provide novel information on the role of ion transport during bacterial death, with the potential to uncover future antimicrobial targets.
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| 14. |
- Dahlman, Disa, et al.
(författare)
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Physical pain is common and associated with nonmedical prescription opioid use among people who inject drugs
- 2017
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Ingår i: Substance Abuse: Treatment, Prevention, and Policy. - : Springer Science and Business Media LLC. - 1747-597X. ; 12:1, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Background: People who inject drugs (PWID) often have poor health and lack access to health care. The aim of this study was to examine whether PWID engage in self-treatment through nonmedical prescription opioid use (NMPOU). We describe the prevalence and features of self-reported physical pain and its association with NMPOU. Methods: PWID (N = 702) in San Francisco, California (age 18+) were recruited to complete interviewer administered surveys between 2011 and 2013. Multivariate logistic regression analysis was conducted to examine the associations among self-reported pain dimensions (past 24-h average pain, pain interference with functional domains) and NMPOU, controlling for age, sex, psychiatric illness, opioid substitution treatment, homelessness, street heroin use and unmet healthcare needs. Results: Almost half of the sample reported pain, based on self-reported measures in the 24 h before their interview. The most common pain locations were to their back and lower extremities. Past 24-h NMPOU was common (14.7%) and associated with past 24 h average pain intensity on a 10 point self-rating scale (adjusted odds ratio [AOR] = 2.15, 95% confidence interval [CI] 1.21-3.80), and past 24 h pain interference with general activity (AOR 1.82 [95% CI 1.04-3.21]), walking ability (AOR 2.52 [95% CI 1.37-4.63]), physical ability (AOR 2.01 [95% CI 1.16-3.45]), sleep (AOR 1.98 [95% CI 1.13-3.48]) and enjoyment of life (AOR 1.79 [95% CI 1.02-3.15]). Conclusion: Both pain and NMPOU are common among PWID, and highly correlated in this study. These findings suggest that greater efforts are needed to direct preventive health and services toward this population.
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| 15. |
- De, Supradipta, et al.
(författare)
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Measuring Niche-Associated Metabolic Activity in Planktonic and Biofilm Bacteria
- 2023. - 2
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Ingår i: Bacterial pathogenesis : Methods and protocols - Methods and protocols. - 1940-6029. - 9781071632437 ; , s. 3-32
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Bokkapitel (refereegranskat)abstract
- Most pathobionts of the respiratory tract form biofilms during asymptomatic colonization to survive and persist in this niche. Environmental changes of the host niche, often resulting from infection with respiratory viruses, changes of the microbiota composition, or other host assaults, can result in biofilm dispersion and spread of bacteria to other host niches, resulting in infections, such as otitis media, pneumonia, sepsis, and meningitis. The niches that these bacteria encounter during colonization and infection vary markedly in nutritional availability and contain different carbon sources and levels of other essential nutrients needed for bacterial growth and survival. As these niche-related nutritional variations regulate bacterial behavior and phenotype, a better understanding of bacterial niche-associated metabolic activity is likely to provide a broader understanding of bacterial pathogenesis. In this chapter, we use Streptococcus pneumoniae as a model respiratory pathobiont. We describe methods and models used to grow bacteria planktonically or to form biofilms in vitro by incorporating crucial host environmental factors, including the various carbon sources associated with specific niches, such as the nasopharynx or bloodstream. We then present methods describing how these models can be used to study bacterial phenotypes and their association with metabolic energy production and the generation of fermentation products.
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| 16. |
- Demers-Mathieu, Veronique, et al.
(författare)
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Functional Antibodies Against SARS-CoV-2 Receptor Binding Domain Variants with Mutations N501Y or E484K in Human Milk from COVID-19-Vaccinated, -Recovered, and -Unvaccinated Women
- 2022
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Ingår i: Breastfeeding Medicine. - : Mary Ann Liebert Inc. - 1556-8253 .- 1556-8342. ; 17:2, s. 163-172
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Tidskriftsartikel (refereegranskat)abstract
- Background: New variants are evolving in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and receptor binding domain (RBD) mutations have been associated with a higher capacity to evade neutralizing antibodies (NAbs). We aimed at determining the impact of COVID-19 vaccine and infection on human milk antibody titers and activity against the RBD mutations from SARS-CoV-2 variants of concern. Materials and Methods: Milk samples were collected from 19 COVID-19 vaccinated women, 10 women who had a positive COVID-19 PCR test, and 13 unvaccinated women. The titers and NAbs of secretory IgA (SIgA)/IgA, secretory IgM (IgM)/IgM, and IgG against SARS-CoV-2 RBD with mutations N501Y or E484K were measured by using ELISA and a surrogate virus neutralization assay. Results: The titers of human milk IgG against N501Y were higher in the COVID-19 vaccine group than in the no-vaccine group but comparable with the COVID-19 PCR group. Other antibody titers did not differ between the three groups. The titers of SIgA/IgA were higher than those of SIgM/IgM and IgG in all three groups. The titers of SIgM/IgM and the inhibition of NAbs were higher against the mutation E484K than N501Y. Milk NAb did not differ between the three groups, but the inhibition of NAb against binding of the two mutant RBD proteins to their receptor was higher in the COVID-19 vaccine and PCR groups than in milk from prepandemic women. Conclusions: COVID-19 vaccination and exposure of mothers to SARS-CoV-2 influenced the titers and NAbs in breast milk against the variants of concern.
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| 17. |
- Enoksson, Frida, et al.
(författare)
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Niche- and gender-dependent immune reactions in relation to the microbiota profile in pediatric patients with otitis media with effusion
- 2020
-
Ingår i: Infection and Immunity. - 1098-5522. ; 88:10
-
Tidskriftsartikel (refereegranskat)abstract
- Otitis media with effusion (OME) is a common inflammatory disease, primarily affecting children. OME is defined as a chronic low-grade inflammation of the middle ear (ME), without any signs of infection and with effusion persisting in the ME for more than three months. The precise pathogenesis is, however, not fully understood. Here, we comprehensively characterized and compared the host immune responses (inflammatory cells and mediators) and the overall microbial community composition (microbiota) present in matched middle ear effusion samples (MEE), external ear canal lavages, and nasopharynx (NPH) samples from children with OME. Female patients had significantly increased percentages of T lymphocytes and higher levels of a wide array of inflammatory mediators in their MEEs compared to male patients, which was unrelated to microbiota composition. The relative abundances of identified microorganisms were strongly associated with their niche of origin. Furthermore, specific inflammatory mediators were highly correlated with certain bacterial species. Interestingly, some organisms displayed a niche-driven inflammation pattern, where presence of Haemophilus spp and Corynebacterium propinquum in MEEs was accompanied by pro-inflammatory mediators, whereas their presence in NPH was accompanied by anti-inflammatory mediators. For Turicella and Alloiococcus we found exactly the opposite results, i.e., an anti-inflammatory profile when present in MEEs, whereas their presence in the NPH was accompanied by a pro-inflammatory profile. Altogether, our results indicate that immune responses in children with OME are highly niche- and microbiota-driven, but gender-based differences were also observed, providing novel insight into potential pathogenic mechanisms behind OME.
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| 18. |
- Eriksson, P, et al.
(författare)
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Neonatal exposure to DDT and its fatty acid conjugate: effects on cholinergic and behavioural variables in the adult mouse
- 1990
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Ingår i: NeuroToxicology. - 1872-9711. ; 11:2, s. 345-354
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Tidskriftsartikel (refereegranskat)abstract
- We have recently observed that DDT and a DDT metabolite, DDOH, conjugated to a fatty acid, palmitic acid, DDOH-PA, affects muscarinic cholinergic receptors (MAChR) in the neonatal mouse brain when given to suckling mice during rapid brain growth. This early exposure of the neonatal mouse also affects the behaviour of the animals as adults. When DDT and DDOH-PA was given as a single low oral dose of 1.4 mumol/kg body weight, DDT (0.5 mg), DDOH-PA (0.7 mg) and a 20% fat emulsion vehicle (10 ml) per kg body weight to 10-day-old NMRI mice, behavioural tests at adult age of four months, indicated disruption of a simple, non-associative learning process, i.e. habituation, in both DDT and DDOH-PA treated mice. There was also a significant increase in the potassium evoked release of ACh from slices of cerebral cortex and a tendency towards a decrease in the density of MAChR in mice receiving DDT. These effects in the adult mice could not be correlated to the concentration of DDT in the adult brain since DDT one month after its administration to the 10-day-old mouse no longer is present in the brain.
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| 19. |
- Greene, Christopher J., et al.
(författare)
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A novel strategy to protect against influenza-induced pneumococcal disease without interfering with commensal colonization
- 2016
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Ingår i: Infection and Immunity. - 1098-5522. ; 84:6, s. 1693-1703
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pneumoniae commonly inhabits the nasopharynx as a member of the commensal biofilm. Infection with respiratory viruses, such as influenza A virus, induces commensal S. pneumoniae to disseminate beyond the nasopharynx and to elicit severe infections of the middle ears, lungs, and blood that are associated with high rates of morbidity and mortality. Current preventive strategies, including the polysaccharide conjugate vaccines aim to eliminate asymptomatic carriage with vaccine-type pneumococci. However, this has resulted in serotype-replacement with, so-far, less fit pneumococcal strains, which has changed the nasopharyngeal flora, opening the niche for entry of other virulent pathogens (e.g., Streptococcus pyogenes, Staphylococcus aureus, and potentially Haemophilus influenzae). The long-term effects of these changes are unknown. Here, we present an attractive, alternative preventive approach where we subvert virally-induced pneumococcal disease without interfering with commensal colonization, thus specifically targeting disease-causing organisms. In that regard, pneumococcal surface protein A (PspA), a major surface protein of pneumococci, is a promising vaccine target. Intradermal (i.d.) immunization of mice with recombinant PspA in combination with LT-IIb(T13I), a novel i.d. adjuvant of the type II heat-labile enterotoxin family, elicited strong systemic PspA-specific IgG responses without inducing mucosal anti-PspA IgA responses. This response protected mice from otitis media, pneumonia, and septicemia and averted the cytokine storm associated with septic infection but had no effect on asymptomatic colonization. Our results firmly demonstrated that this immunization strategy against virally-induced, pneumococcal disease can be conferred without disturbing the desirable pre-existing commensal colonization of the nasopharynx.
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| 20. |
- Guerra, Maria Eduarda Souza, et al.
(författare)
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Klebsiella pneumoniae Biofilms and Their Role in Disease Pathogenesis.
- 2022
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Ingår i: Frontiers in cellular and infection microbiology. - : Frontiers Media SA. - 2235-2988. ; 12, s. 1-13
-
Forskningsöversikt (refereegranskat)abstract
- The ability to form biofilms is a crucial virulence trait for several microorganisms, including Klebsiella pneumoniae - a Gram-negative encapsulated bacterium often associated with nosocomial infections. It is estimated that 65-80% of bacterial infections are biofilm related. Biofilms are complex bacterial communities composed of one or more species encased in an extracellular matrix made of proteins, carbohydrates and genetic material derived from the bacteria themselves as well as from the host. Bacteria in the biofilm are shielded from immune responses and antibiotics. The present review discusses the characteristics of K. pneumoniae biofilms, factors affecting biofilm development, and their contribution to infections. We also explore different model systems designed to study biofilm formation in this species. A great number of factors contribute to biofilm establishment and maintenance in K. pneumoniae, which highlights the importance of this mechanism for the bacterial fitness. Some of these molecules could be used in future vaccines against this bacterium. However, there is still a lack of in vivo models to evaluate the contribution of biofilm development to disease pathogenesis. With that in mind, the combination of different methodologies has great potential to provide a more detailed scenario that more accurately reflects the steps and progression of natural infection.
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| 21. |
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| 22. |
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| 23. |
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| 24. |
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| 25. |
- Håkansson, Anders P, et al.
(författare)
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Apoptosis-Like Death in Bacteria Induced by HAMLET, a Human Milk Lipid-Protein Complex
- 2011
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:3
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Tidskriftsartikel (refereegranskat)abstract
- Background: Apoptosis is the primary means for eliminating unwanted cells in multicellular organisms in order to preserve tissue homeostasis and function. It is characterized by distinct changes in the morphology of the dying cell that are orchestrated by a series of discrete biochemical events. Although there is evidence of primitive forms of programmed cell death also in prokaryotes, no information is available to suggest that prokaryotic death displays mechanistic similarities to the highly regulated programmed death of eukaryotic cells. In this study we compared the characteristics of tumor and bacterial cell death induced by HAMLET, a human milk complex of alpha-lactalbumin and oleic acid. Methodology/Principal Findings: We show that HAMLET-treated bacteria undergo cell death with mechanistic and morphologic similarities to apoptotic death of tumor cells. In Jurkat cells and Streptococcus pneumoniae death was accompanied by apoptosis-like morphology such as cell shrinkage, DNA condensation, and DNA degradation into high molecular weight fragments of similar sizes, detected by field inverse gel electrophoresis. HAMLET was internalized into tumor cells and associated with mitochondria, causing a rapid depolarization of the mitochondrial membrane and bound to and induced depolarization of the pneumococcal membrane with similar kinetic and magnitude as in mitochondria. Membrane depolarization in both systems required calcium transport, and both tumor cells and bacteria were found to require serine protease activity (but not caspase activity) to execute cell death. Conclusions/Significance: Our results suggest that many of the morphological changes and biochemical responses associated with apoptosis are present in prokaryotes. Identifying the mechanisms of bacterial cell death has the potential to reveal novel targets for future antimicrobial therapy and to further our understanding of core activation mechanisms of cell death in eukaryote cells.
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| 26. |
- Joma, Basma H, et al.
(författare)
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A Murine Model for Enhancement of Streptococcus pneumoniae Pathogenicity Upon Viral Infection and Advanced Age
- 2021
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Ingår i: Infection and Immunity. - 1098-5522. ; 89:8
-
Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pneumoniae (pneumococcus) resides asymptomatically in the nasopharynx but can progress from benign colonizer to lethal pulmonary or systemic pathogen. Both viral infection and aging are risk factors for serious pneumococcal infections. Previous work established a murine model that featured the movement of pneumococcus from the nasopharynx to the lung upon nasopharyngeal inoculation with influenza A virus (IAV) but did not fully recapitulate the severe disease associated with human co-infection. We built upon this model by first establishing pneumococcal nasopharyngeal colonization, then inoculating both the nasopharynx and lungs with IAV. In young (2 months) mice, co-infection triggered bacterial dispersal from the nasopharynx into the lungs, pulmonary inflammation, disease and mortality in a fraction of mice. In old mice (20-22 months), co-infection resulted in earlier and more severe disease. Aging was not associated with greater bacterial burdens but rather with more rapid pulmonary inflammation and damage. Both aging and IAV infection led to inefficient bacterial killing by neutrophils ex vivo Conversely, aging and pneumococcal colonization also blunted IFN-α production and increased pulmonary IAV burden. Thus, in this multistep model, IAV promotes pneumococcal pathogenicity by modifying bacterial behavior in the nasopharynx, diminishing neutrophil function, and enhancing bacterial growth in the lung, while pneumococci increase IAV burden likely by compromising a key antiviral response. Thus, this model provides a means to elucidate factors, such as age and co-infection, that promote the evolution of S. pneumoniae from asymptomatic colonizer to invasive pathogen, as well as to investigate consequences of this transition on antiviral defense.
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| 27. |
- Jones, Charles H, et al.
(författare)
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Hybrid biosynthetic gene therapy vector development and dual engineering capacity
- 2014
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 111:34, s. 5-12360
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Tidskriftsartikel (refereegranskat)abstract
- Genetic vaccines offer a treatment opportunity based upon successful gene delivery to specific immune cell modulators. Driving the process is the vector chosen for gene cargo packaging and subsequent delivery to antigen-presenting cells (APCs) capable of triggering an immune cascade. As such, the delivery process must successfully navigate a series of requirements and obstacles associated with the chosen vector and target cell. In this work, we present the development and assessment of a hybrid gene delivery vector containing biological and biomaterial components. Each component was chosen to design and engineer gene delivery separately in a complimentary and fundamentally distinct fashion. A bacterial (Escherichia coli) inner core and a biomaterial [poly(beta-amino ester)]-coated outer surface allowed the simultaneous application of molecular biology and polymer chemistry to address barriers associated with APC gene delivery, which include cellular uptake and internalization, phagosomal escape, and intracellular cargo concentration. The approach combined and synergized normally disparate vector properties and tools, resulting in increased in vitro gene delivery beyond individual vector components or commercially available transfection agents. Furthermore, the hybrid device demonstrated a strong, efficient, and safe in vivo humoral immune response compared with traditional forms of antigen delivery. In summary, the flexibility, diversity, and potential of the hybrid design were developed and featured in this work as a platform for multivariate engineering at the vector and cellular scales for new applications in gene delivery immunotherapy.
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| 28. |
- Lenhard, Alexsandra, et al.
(författare)
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A Mouse Model for the Transition of Streptococcus pneumoniae from Colonizer to Pathogen upon Viral Co-Infection Recapitulates Age-Exacerbated Illness
- 2022
-
Ingår i: Journal of visualized experiments : JoVE. - : MyJove Corporation. - 1940-087X. ; :187, s. 1-27
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pneumoniae (pneumococcus) is an asymptomatic colonizer of the nasopharynx in most individuals but can progress to a pulmonary and systemic pathogen upon influenza A virus (IAV) infection. Advanced age enhances host susceptibility to secondary pneumococcal pneumonia and is associated with worsened disease outcomes. The host factors driving those processes are not well defined, in part due to a lack of animal models that reproduce the transition from asymptomatic colonization to severe clinical disease. This paper describes a novel mouse model that recreates the transition of pneumococci from asymptomatic carriage to disease upon viral infection. In this model, mice are first intranasally inoculated with biofilm-grown pneumococci to establish asymptomatic carriage, followed by IAV infection of both the nasopharynx and lungs. This results in bacterial dissemination to the lungs, pulmonary inflammation, and obvious signs of illness that can progress to lethality. The degree of disease is dependent on the bacterial strain and host factors. Importantly, this model reproduces the susceptibility of aging, because compared to young mice, old mice display more severe clinical illness and succumb to disease more frequently. By separating carriage and disease into distinct steps and providing the opportunity to analyze the genetic variants of both the pathogen and the host, this S. pneumoniae/IAV co-infection model permits the detailed examination of the interactions of an important pathobiont with the host at different phases of disease progression. This model can also serve as an important tool for identifying potential therapeutic targets against secondary pneumococcal pneumonia in susceptible hosts.
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| 29. |
- Li, Yi, et al.
(författare)
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Directed vaccination against pneumococcal disease
- 2016
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 113:25, s. 6898-6903
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Tidskriftsartikel (refereegranskat)abstract
- Immunization strategies against commensal bacterial pathogens have long focused on eradicating asymptomatic carriage as well as disease, resulting in changes in the colonizing microflora with unknown future consequences. Additionally, current vaccines are not easily adaptable to sequence diversity and immune evasion. Here, we present a "smart" vaccine that leverages our current understanding of disease transition from bacterial carriage to infection with the pneumococcus serving as a model organism. Using conserved surface proteins highly expressed during virulent transition, the vaccine mounts an immune response specifically against disease-causing bacterial populations without affecting carriage. Aided by a delivery technology capable of multivalent surface display, which can be adapted easily to a changing clinical picture, results include complete protection against the development of pneumonia and sepsis during animal challenge experiments with multiple, highly variable, and clinically relevant pneumococcal isolates. The approach thus offers a unique and dynamic treatment option readily adaptable to other commensal pathogens.
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| 30. |
- Li, Yi, et al.
(författare)
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In situ pneumococcal vaccine production and delivery through a hybrid biological-biomaterial vector
- 2016
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 2:7
-
Tidskriftsartikel (refereegranskat)abstract
- The type and potency of an immune response provoked during vaccination will determine ultimate success in disease prevention. The basis for this response will be the design and implementation of antigen presentation to the immune system. Whereas direct antigen administration will elicit some form of immunological response, a more sophisticated approach would couple the antigen of interest to a vector capable of broad delivery formats and designed for heightened response. New antigens associated with pneumococcal disease virulence were used to test the delivery and adjuvant capabilities of a hybrid biological-biomaterial vector consisting of a bacterial core electrostatically coated with a cationic polymer. The hybrid design provides (i) passive and active targeting of antigen-presenting cells, (ii) natural and multicomponent adjuvant properties, (iii) dual intracellular delivery mechanisms, and (iv) a simple formulation mechanism. In addition, the hybrid format enables device-specific, or in situ, antigen production and consolidation via localization within the bacterial component of the vector. This capability eliminates the need for dedicated antigen production and purification before vaccination efforts while leveraging the aforementioned features of the overall delivery device. We present the first disease-specific utilization of the vector toward pneumococcal disease highlighted by improved immune responses and protective capabilities when tested against traditional vaccine formulations and a range of clinically relevant Streptococcus pneumoniae strains. More broadly, the results point to similar levels of success with other diseases that would benefit from the production, delivery, and efficacy capabilities offered by the hybrid vector.
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| 31. |
- MacDonald, Brian A, et al.
(författare)
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Halothane modulates the type i interferon response to influenza and minimizes the risk of secondary bacterial pneumonia through maintenance of neutrophil recruitment in an animal model
- 2015
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Ingår i: Anesthesiology. - 1528-1175. ; 123:3, s. 590-602
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: To minimize the risk of pneumonia, many anesthesiologists delay anesthesia-requiring procedures when patients exhibit signs of viral upper respiratory tract infection. Postinfluenza secondary bacterial pneumonias (SBPs) are a major cause of morbidity and mortality. An increased host susceptibility to SBP postinfluenza has been attributed to physical damage to the pulmonary epithelium, but flu-induced effects on the immune system are being shown to also play an important role. The authors demonstrate that halothane mitigates the risk of SBP postflu through modulation of the effects of type I interferon (IFN).METHODS: Mice (n = 6 to 15) were exposed to halothane or ketamine and treated with influenza and Streptococcus pneumoniae. Bronchoalveolar lavage and lung homogenate were procured for the measurement of inflammatory cells, cytokines, chemokines, albumin, myeloperoxidase, and bacterial load.RESULTS: Halothane exposure resulted in decreased bacterial burden (7.9 ± 3.9 × 10 vs. 3.4 ± 1.6 × 10 colony-forming units, P < 0.01), clinical score (0.6 ± 0.2 vs. 2.3 ± 0.2, P < 0.0001), and lung injury (as measured by bronchoalveolar lavage albumin, 1.5 ± 0.7 vs. 6.8 ± 1.6 mg/ml, P < 0.01) in CD-1 mice infected with flu for 7 days and challenged with S. pneumoniae on day 6 postflu. IFN receptor A1 knockout mice similarly infected with flu and S. pneumoniae, but not exposed to halothane, demonstrated a reduction of lung bacterial burden equivalent to that achieved in halothane-exposed wild-type mice.CONCLUSION: These findings indicate that the use of halogenated volatile anesthetics modulates the type I IFN response to influenza and enhance postinfection antibacterial immunity.
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| 32. |
- Marks, Laura R, et al.
(författare)
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High levels of genetic recombination during nasopharyngeal carriage and biofilm formation in Streptococcus pneumoniae
- 2012
-
Ingår i: mBio. - 2161-2129. ; 3:5
-
Tidskriftsartikel (refereegranskat)abstract
- UNLABELLED: Transformation of genetic material between bacteria was first observed in the 1920s using Streptococcus pneumoniae as a model organism. Since then, the mechanism of competence induction and transformation has been well characterized, mainly using planktonic bacteria or septic infection models. However, epidemiological evidence suggests that genetic exchange occurs primarily during pneumococcal nasopharyngeal carriage, which we have recently shown is associated with biofilm growth, and is associated with cocolonization with multiple strains. However, no studies to date have comprehensively investigated genetic exchange during cocolonization in vitro and in vivo or the role of the nasopharyngeal environment in these processes. In this study, we show that genetic exchange during dual-strain carriage in vivo is extremely efficient (10(-2)) and approximately 10,000,000-fold higher than that measured during septic infection (10(-9)). This high transformation efficiency was associated with environmental conditions exclusive to the nasopharynx, including the lower temperature of the nasopharynx (32 to 34°C), limited nutrient availability, and interactions with epithelial cells, which were modeled in a novel biofilm model in vitro that showed similarly high transformation efficiencies. The nasopharyngeal environmental factors, combined, were critical for biofilm formation and induced constitutive upregulation of competence genes and downregulation of capsule that promoted transformation. In addition, we show that dual-strain carriage in vivo and biofilms formed in vitro can be transformed during colonization to increase their pneumococcal fitness and also, importantly, that bacteria with lower colonization ability can be protected by strains with higher colonization efficiency, a process unrelated to genetic exchange.IMPORTANCE: Although genetic exchange between pneumococcal strains is known to occur primarily during colonization of the nasopharynx and colonization is associated with biofilm growth, this is the first study to comprehensively investigate transformation in this environment and to analyze the role of environmental and bacterial factors in this process. We show that transformation efficiency during cocolonization by multiple strains is very high (around 10(-2)). Furthermore, we provide novel evidence that specific aspects of the nasopharyngeal environment, including lower temperature, limited nutrient availability, and epithelial cell interaction, are critical for optimal biofilm formation and transformation efficiency and result in bacterial protein expression changes that promote transformation and fitness of colonization-deficient strains. The results suggest that cocolonization in biofilm communities may have important clinical consequences by facilitating the spread of antibiotic resistance and enabling serotype switching and vaccine escape as well as protecting and retaining poorly colonizing strains in the pneumococcal strain pool.
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| 33. |
- Marks, Laura R, et al.
(författare)
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Pneumococcal interactions with epithelial cells are crucial for optimal biofilm formation and colonization in vitro and in vivo
- 2012
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Ingår i: Infection and Immunity. - 1098-5522. ; 80:8, s. 60-2744
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Tidskriftsartikel (refereegranskat)abstract
- The human nasopharynx is the main reservoir for Streptococcus pneumoniae (the pneumococcus) and the source for both horizontal spread and transition to infection. Some clinical evidence indicates that nasopharyngeal carriage is harder to eradicate with antibiotics than is pneumococcal invasive disease, which may suggest that colonizing pneumococci exist in biofilm communities that are more resistant to antibiotics. While pneumococcal biofilms have been observed during symptomatic infection, their role in colonization and the role of host factors in this process have been less studied. Here, we show for the first time that pneumococci form highly structured biofilm communities during colonization of the murine nasopharynx that display increased antibiotic resistance. Furthermore, pneumococcal biofilms grown on respiratory epithelial cells exhibited phenotypes similar to those observed during colonization in vivo, whereas abiotic surfaces produced less ordered and more antibiotic-sensitive biofilms. The importance of bacterial-epithelial cell interactions during biofilm formation was shown using both clinical strains with variable colonization efficacies and pneumococcal mutants with impaired colonization characteristics in vivo. In both cases, the ability of strains to form biofilms on epithelial cells directly correlated with their ability to colonize the nasopharynx in vivo, with colonization-deficient strains forming less structured and more antibiotic-sensitive biofilms on epithelial cells, an association that was lost when grown on abiotic surfaces. Thus, these studies emphasize the importance of host-bacterial interactions in pneumococcal biofilm formation and provide the first experimental data to explain the high resistance of pneumococcal colonization to eradication by antibiotics.
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| 34. |
- Marks, Laura R, et al.
(författare)
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Streptococcus pyogenes biofilm growth in vitro and in vivo and its role in colonization, virulence, and genetic exchange
- 2014
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Ingår i: Journal of Infectious Diseases. - : Oxford University Press (OUP). - 1537-6613 .- 0022-1899. ; 210:1, s. 25-34
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Group A streptococcus (GAS) commonly colonizes the oropharynx and nonintact skin. However, colonization has been little studied and the role of biofilm formation is unclear, as biofilm experiments to date have not been conducted under conditions that mimic the host environment.METHODS: In this study we grew GAS biofilms on human keratinocytes under various environmental conditions and used this model to evaluate colonization, invasive disease and natural transformation.RESULTS: GAS grown on epithelial cells, but not biofilms grown on abiotic surfaces, produced biofilms with characteristics similar to in vivo colonization. These biofilm bacteria showed a 100-fold higher bacterial burden of nasal-associated lymphoid tissue in mice than broth-grown bacteria, and were not virulent during septic infection, which was attributed in part to down-regulation of genes typically involved in localized and invasive disease. We also showed for the first time that GAS were naturally transformable when grown in biofilms and during colonization of NALT in vivo.CONCLUSIONS: These findings provide novel model systems to study biofilm formation of GAS in vitro and in vivo, suggest an important role for biofilm formation during GAS colonization, and provide an explanation for the known genome diversity within the GAS population.
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| 35. |
- Marks, Laura R, et al.
(författare)
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The human milk protein-lipid complex HAMLET sensitizes bacterial pathogens to traditional antimicrobial agents
- 2012
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:8, s. 43514-43514
-
Tidskriftsartikel (refereegranskat)abstract
- The fight against antibiotic resistance is one of the most significant challenges to public health of our time. The inevitable development of resistance following the introduction of novel antibiotics has led to an urgent need for the development of new antibacterial drugs with new mechanisms of action that are not susceptible to existing resistance mechanisms. One such compound is HAMLET, a natural complex from human milk that kills Streptococcus pneumoniae (the pneumococcus) using a mechanism different from common antibiotics and is immune to resistance-development. In this study we show that sublethal concentrations of HAMLET potentiate the effect of common antibiotics (penicillins, macrolides, and aminoglycosides) against pneumococci. Using MIC assays and short-time killing assays we dramatically reduced the concentrations of antibiotics needed to kill pneumococci, especially for antibiotic-resistant strains that in the presence of HAMLET fell into the clinically sensitive range. Using a biofilm model in vitro and nasopharyngeal colonization in vivo, a combination of HAMLET and antibiotics completely eradicated both biofilms and colonization in mice of both antibiotic-sensitive and resistant strains, something each agent alone was unable to do. HAMLET-potentiation of antibiotics was partially due to increased accessibility of antibiotics to the bacteria, but relied more on calcium import and kinase activation, the same activation pathway HAMLET uses when killing pneumococci by itself. Finally, the sensitizing effect was not confined to species sensitive to HAMLET. The HAMLET-resistant respiratory species Acinetobacter baumanii and Moraxella catarrhalis were all sensitized to various classes of antibiotics in the presence of HAMLET, activating the same mechanism as in pneumococci. Combined these results suggest the presence of a conserved HAMLET-activated pathway that circumvents antibiotic resistance in bacteria. The ability to activate this pathway may extend the lifetime of the current treatment arsenal.
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| 36. |
- Meikle, Virginia, et al.
(författare)
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A protein complex from human milk enhances the activity of antibiotics and drugs against Mycobacterium tuberculosis
- 2019
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Ingår i: Antimicrobial Agents and Chemotherapy. - 1098-6596. ; 63:2
-
Tidskriftsartikel (refereegranskat)abstract
- Mycobacterium tuberculosis, the causative agent of human tuberculosis (TB), has surpassed HIV/AIDS as the leading cause of death from a single infectious agent. The increasing occurrence of drug-resistant strains has become a major challenge for health care systems and, in some cases, has rendered TB untreatable. However, the development of new TB drugs has been plagued with high failure rates and costs. Alternative strategies to increase the efficacy of current TB treatment regimens include host-directed therapies or agents that make M. tuberculosis more susceptible to existing TB drugs. In this study, we show that HAMLET, an -lactalbumin–oleic acid complex derived from human milk, has bactericidal activity against M. tuberculosis. HAMLET consists of a micellar oleic acid core surrounded by a shell of partially denatured -lactalbumin molecules and unloads oleic acid into cells upon contact with lipid membranes. At sublethal concentrations, HAMLET potentiated a remarkably broad array of TB drugs and antibiotics against M. tuberculosis. For example, the minimal inhibitory concentrations of rifampin, bedaquiline, delamanid, and clarithromycin were decreased by 8- to 16-fold. HAMLET also killed M. tuberculosis and enhanced the efficacy of TB drugs inside macrophages, a natural habitat of M. tuberculosis. Previous studies showed that HAMLET is stable after oral delivery in mice and nontoxic in humans and that it is possible to package hydrophobic compounds in the oleic acid core of HAMLET to increase their solubility and metabolic stability. The potential of HAMLET and other liprotides as drug delivery and sensitization agents in TB chemotherapy is discussed here.
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| 37. |
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| 38. |
- Pettigrew, Melinda M, et al.
(författare)
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Panel 6 : Vaccines
- 2017
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Ingår i: Otolaryngology - Head and Neck Surgery. - : Wiley. - 0194-5998 .- 1097-6817. ; 156:4_suppl, s. 76-87
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To review the literature on progress regarding (1) effectiveness of vaccines for prevention of otitis media (OM) and (2) development of vaccine antigens for OM bacterial and viral pathogens. Data Sources: PubMed database of the National Library of Science. Review Methods: We performed literature searches in PubMed for OM pathogens and candidate vaccine antigens, and we restricted the searches to articles in English that were published between July 2011 and June 2015. Panel members reviewed literature in their area of expertise. Conclusions: Pneumococcal conjugate vaccines (PCVs) are somewhat effective for the prevention of pneumococcal OM, recurrent OM, OM visits, and tympanostomy tube insertions. Widespread use of PCVs has been associated with shifts in pneumococcal serotypes and bacterial pathogens associated with OM, diminishing PCV effectiveness against AOM. The 10-valent pneumococcal vaccine containing Haemophilus influenzae protein D (PHiD-CV) is effective for pneumococcal OM, but results from studies describing the potential impact on OM due to H influenzae have been inconsistent. Progress in vaccine development for H influenzae, Moraxella catarrhalis, and OM-associated respiratory viruses has been limited. Additional research is needed to extend vaccine protection to additional pneumococcal serotypes and other otopathogens. There are likely to be licensure challenges for protein-based vaccines, and data on correlates of protection for OM vaccine antigens are urgently needed. Implications for Practice: OM continues to be a significant health care burden globally. Prevention is preferable to treatment, and vaccine development remains an important goal. As a polymicrobial disease, OM poses significant but not insurmountable challenges for vaccine development.
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| 39. |
- Reddinger, Ryan M, et al.
(författare)
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Host Physiologic Changes Induced by Influenza A Virus Lead to Staphylococcus aureus Biofilm Dispersion and Transition from Asymptomatic Colonization to Invasive Disease
- 2016
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Ingår i: mBio. - 2161-2129. ; 7:4
-
Tidskriftsartikel (refereegranskat)abstract
- UNLABELLED: Staphylococcus aureus is a ubiquitous opportunistic human pathogen and a major health concern worldwide, causing a wide variety of diseases from mild skin infections to systemic disease. S. aureus is a major source of severe secondary bacterial pneumonia after influenza A virus infection, which causes widespread morbidity and mortality. While the phenomenon of secondary bacterial pneumonia is well established, the mechanisms behind the transition from asymptomatic colonization to invasive staphylococcal disease following viral infection remains unknown. In this report, we have shown that S. aureus biofilms, grown on an upper respiratory epithelial substratum, disperse in response to host physiologic changes related to viral infection, such as febrile range temperatures, exogenous ATP, norepinephrine, and increased glucose. Mice that were colonized with S. aureus and subsequently exposed to these physiologic stimuli or influenza A virus coinfection developed pronounced pneumonia. This study provides novel insight into the transition from colonization to invasive disease, providing a better understanding of the events involved in the pathogenesis of secondary staphylococcal pneumonia.IMPORTANCE: In this study, we have determined that host physiologic changes related to influenza A virus infection causes S. aureus to disperse from a biofilm state. Additionally, we report that these same host physiologic changes promote S. aureus dissemination from the nasal tissue to the lungs in an animal model. Furthermore, this study identifies important aspects involved in the transition of S. aureus from asymptomatic colonization to pneumonia.
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| 40. |
- Reddinger, Ryan M, et al.
(författare)
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Streptococcus pneumoniae Modulates Staphylococcus aureus Biofilm Dispersion and the Transition from Colonization to Invasive Disease.
- 2018
-
Ingår i: mBio. - 2161-2129. ; 9:1
-
Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pneumoniae and Staphylococcus aureus are ubiquitous upper respiratory opportunistic pathogens. Individually, these Gram-positive microbes are two of the most common causative agents of secondary bacterial pneumonia following influenza A virus infection, and they constitute a significant source of morbidity and mortality. Since the introduction of the pneumococcal conjugate vaccine, rates of cocolonization with both of these bacterial species have increased, despite the traditional view that they are antagonistic and mutually exclusive. The interactions between S. pneumoniae and S. aureus in the context of colonization and the transition to invasive disease have not been characterized. In this report, we show that S. pneumoniae and S. aureus form stable dual-species biofilms on epithelial cells in vitro When these biofilms are exposed to physiological changes associated with viral infection, S. pneumoniae disperses from the biofilm, whereas S. aureus dispersal is inhibited. These findings were supported by results of an in vivo study in which we used a novel mouse cocolonization model. In these experiments, mice cocolonized in the nares with both bacterial species were subsequently infected with influenza A virus. The coinfected mice almost exclusively developed pneumococcal pneumonia. These results indicate that despite our previous report that S. aureus disseminates into the lungs of mice stably colonized with these bacteria following influenza A virus infection, cocolonization with S. pneumoniae in vitro and in vivo inhibits S. aureus dispersal and transition to disease. This study provides novel insight into both the interactions between S. pneumoniae and S. aureus during carriage and the transition from colonization to secondary bacterial pneumonia.IMPORTANCE In this study, we demonstrate that Streptococcus pneumoniae can modulate the pathogenic potential of Staphylococcus aureus in a model of secondary bacterial pneumonia. We report that host physiological signals related to viral infection cease to elicit a dispersal response from S. aureus while in a dual-species setting with S. pneumoniae, in direct contrast to results of previous studies with each species individually. This study underscores the importance of studying polymicrobial communities and their implications in disease states.
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| 41. |
- Waz, Natalha T, et al.
(författare)
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Influence of the Polysaccharide Capsule on the Bactericidal Activity of Indolicidin on Streptococcus pneumoniae.
- 2022
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Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 13, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pneumoniae is a pathogen responsible for high morbidity and mortality worldwide. The polysaccharide capsule confers protection against phagocytosis and influences many aspects of pneumococcal pathogenesis. The capsular polysaccharides (CPS) are highly immunogenic and exhibit great structural variability, with more than 100 serotypes described so far. Antimicrobial peptides (AMPs) are an important part of the innate defense mechanisms against many pathogens. Indolicidin is a cationic AMP produced by bovine neutrophils, with bactericidal effects against several bacteria. CPS has been shown to interfere with the ability of AMPs to kill pneumococci, but the effects of capsule variability on susceptibility to indolicidin have not been explored. The present work determined the effects of capsule on resistance to indolicidin in vitro. Using a bactericidal plate assay, we observed that different pneumococcal serotypes exhibited variable resistance to indolicidin, which correlated with the capsule net charge. Interestingly, the effect of capsule expression on resistance to indolicidin was dependent on the serotype; bacteria with lower zeta potential were more resistant to indolicidin when capsule was present, while those with less negative surface charge were more resistant in the absence of capsule. The addition of purified CPS partially rescued the bacteria from the bactericidal effects of indolicidin, while the addition of anticapsular antibodies accentuated the peptide's bactericidal action, suggesting a possible new protective mechanism induced by polysaccharide-based pneumococcal vaccines.
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