| 1. |
- Potempa, Michal, et al.
(författare)
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Binding of complement inhibitor C4b-binding protein contributes to serum resistance of Porphyromonas gingivalis.
- 2008
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Ingår i: Journal of immunology. - 1550-6606. ; 181:8, s. 5537-5544
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Tidskriftsartikel (refereegranskat)abstract
- The periodontal pathogen Porphyromonas gingivalis is highly resistant to the bactericidal activity of human complement, which is present in the gingival crevicular fluid at 70% of serum concentration. All thirteen clinical and laboratory P. gingivalis strains tested were able to capture the human complement inhibitor C4b-binding protein (C4BP), which may contribute to their serum resistance. Accordingly, in serum deficient of C4BP, it was found that significantly more terminal complement component C9 was deposited on P. gingivalis. Moreover, using purified proteins and various isogenic mutants, we found that the cysteine protease high molecular weight arginine-gingipain A (HRgpA) is a crucial C4BP ligand on the bacterial surface. Binding of C4BP to P. gingivalis appears to be localized to two binding sites: on the complement control protein 1 domain and complement control protein 6 and 7 domains of the alpha-chains. Furthermore, the bacterial binding of C4BP was found to increase with time of culture and a particularly strong binding was observed for large aggregates of bacteria that formed during culture on solid blood agar medium. Taken together, gingipains appear to be a very significant virulence factor not only destroying complement due to proteolytic degradation as we have shown previously, but was also inhibiting complement activation due to their ability to bind the complement inhibitor C4BP.
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| 2. |
- Jendholm, Johan, et al.
(författare)
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Superantigen- and TLR-dependent activation of tonsillar B cells after receptor-mediated endocytosis.
- 2009
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Ingår i: Journal of immunology. - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 182:8, s. 4713-4720
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Tidskriftsartikel (refereegranskat)abstract
- Classical B lymphocyte activation is dependent on BCR cross-linking in combination with physical interaction with Th cells. Other B cell molecules that contribute to the activation are complement, cytokine, and TLRs recognizing specific pathogen-associated molecular patterns. Moraxella (Branhamella) catarrhalis is a common Gram-negative respiratory pathogen that induces proliferation in human IgD-expressing B cells independently of T cell help. The activation is initiated by the B cell superantigen Moraxella IgD-binding protein (MID) through a nonimmune cross-linking of IgD. However, IgD cross-linking alone is not sufficient to induce proliferation. In this study, we characterized the significance of TLRs in superantigen-dependent B cell activation using whole bacteria or rMID in the presence or absence of TLR ligands. IgD cross-linking by MID sensitized B cells obtained from children with tonsillar hyperplasia for mainly TLR9, whereas TLRs 1, 2, 6, and 7 were less important. The Moraxella-induced activation was inhibited when a dominant-negative TLR9 ligand was added. Interestingly, BCR-mediated endocytosis of whole Moraxella and degradation of live bacteria in naive B cells were observed with fluorescence, confocal, and transmission electron microscopy. This unique observation proved the strong intracellular TLR9 response as well as highlighted the Ag-presenting function of B cells. In conclusion, our findings suggest an important role of TLRs in the adaptive immune response and reveal novel insights into the T cell-independent B cell activation induced by bacteria.
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| 3. |
- Singh, Birendra, et al.
(författare)
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Assays for Studying the Role of Vitronectin in Bacterial Adhesion and Serum Resistance
- 2018
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Ingår i: Journal of Visualized Experiments. - Cambride, USA : Journal of Visualized Experiments. - 1940-087X. ; :140
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Tidskriftsartikel (refereegranskat)abstract
- Bacteria utilize complement regulators as a means of evading the host immune response. Here, we describe protocols for evaluating the role vitronectin acquisition at the bacterial cell surface plays in resistance to the host immune system. Flow cytometry experiments identified human plasma vitronectin as a ligand for the bacterial receptor outer membrane protein H of Haemophilus influenzae type f. An enzyme-linked immunosorbent assay was employed to characterize the protein-protein interactions between purified recombinant protein H and vitronectin, and binding affinity was assessed using bio-layer interferometry. The biological importance of the binding of vitronectin to protein H at the bacterial cell surface in evasion of the host immune response was confirmed using a serum resistance assay with normal and vitronectin-depleted human serum. The importance of vitronectin in bacterial adherence was analyzed using glass slides with and without vitronectin coating, followed by Gram staining. Finally, bacterial adhesion to human alveolar epithelial cell monolayers was investigated. The protocols described here can be easily adapted to the study of any bacterial species of interest.
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| 4. |
- Karlsson, Johanna, 1973, et al.
(författare)
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Comparative Study of Immune Status to Infectious Agents in Elderly Patients with Multiple Myeloma, Waldenstrom's Macroglobulinemia, and Monoclonal Gammopathy of Undetermined Significance.
- 2011
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Ingår i: Clinical and vaccine immunology : CVI. - 1556-6811. ; 18:6, s. 969-77
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Tidskriftsartikel (refereegranskat)abstract
- Whereas patients with multiple myeloma (MM) have a well-documented susceptibility to infections, this has been less studied in other B-cell disorders, such as Waldenstrom's macroglobulinemia (WM) and monoclonal gammopathy of undetermined significance (MGUS). We investigated the humoral immunity to 24 different pathogens in elderly patients with MM (n = 25), WM (n = 16), and MGUS (n = 18) and in age-matched controls (n = 20). Antibody titers against pneumococci, staphylococcal alpha-toxin, tetanus and diphtheria toxoids, and varicella, mumps, and rubella viruses were most depressed in MM patients, next to lowest in WM and MGUS patients, and highest in the controls. In contrast, levels of antibodies specific for staphylococcal teichoic acid, Moraxella catarrhalis, candida, aspergillus, and measles virus were similarly decreased in MM and MGUS patients. Comparable titers in all study groups were seen against Haemophilus influenzae type b (Hib), borrelia, toxoplasma, and members of the herpesvirus family. Finally, a uniform lack of antibodies was noted against Streptococcus pyogenes, salmonella, yersinia, brucella, francisella, and herpes simplex virus type 2. To conclude, although MM patients displayed the most depressed humoral immunity, significantly decreased antibody levels were also evident in patients with WM and MGUS, particularly against Staphylococcus aureus, pneumococci, and varicella. Conversely, immunity was retained for Hib and certain herpesviruses in all study groups.
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| 5. |
- Mukherjee, Oindrilla, et al.
(författare)
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A fusion protein derived from Moraxella catarrhalis and Neisseria meningitidis aimed for immune modulation of human B cells
- 2015
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Ingår i: Human Vaccines & Immunotherapeutics. - : Informa UK Limited. - 2164-5515 .- 2164-554X. ; 11:9, s. 2223-2227
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Tidskriftsartikel (refereegranskat)abstract
- Moraxella IgD-binding protein (MID) is a well characterized trimeric autotransporter that specifically targets the IgD of B cells. We fused the membrane anchor of the meningococcal autotransporter NhhA with the IgD-binding region of MID (aa 962-1200) to create a chimeric protein designated as NID. The aim was to use this specific targeting to provide a better vaccine candidate against meningococci, in particular serogroup B by enhancing the immunogenicity of NhhA. NID was thereafter recombinantly expressed in E. coli. The NID-expressing E. coli bound to peripheral B lymphocytes that resulted in cellular activation. Furthermore, we also successfully expressed NID on outer membrane vesicles, nanoparticles that are commonly used in meningococcal vaccines. This study thus highlights the applicability of the menigococcal-Moraxella fusion protein NID to be used for specific targeting of vaccine components to the IgD B cell receptor.
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| 6. |
- Abdillahi, Suado M, et al.
(författare)
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The Pulmonary Extracellular Matrix Is a Bactericidal Barrier Against Haemophilus influenzae in Chronic Obstructive Pulmonary Disease (COPD) : Implications for an in vivo Innate Host Defense Function of Collagen VI
- 2018
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Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Non-typeable Haemophilus influenzae (NTHi) is a Gram-negative human commensal commonly residing in the nasopharynx of preschool children. It occasionally causes upper respiratory tract infection such as acute otitis media, but can also spread to the lower respiratory tract causing bronchitis and pneumonia. There is increasing recognition that NTHi has an important role in chronic lower respiratory tract inflammation, particularly in persistent infection in patients suffering from chronic obstructive pulmonary disease (COPD). Here, we set out to assess the innate protective effects of collagen VI, a ubiquitous extracellular matrix component, against NTHi infection in vivo. In vitro, collagen VI rapidly kills bacteria through pore formation and membrane rupture, followed by exudation of intracellular content. This effect is mediated by specific binding of the von Willebrand A (VWA) domains of collagen VI to the NTHi surface adhesins protein E (PE) and Haemophilus autotransporter protein (Hap). Similar observations were made in vivo specimens from murine airways and COPD patient biopsies. NTHi bacteria adhered to collagen fibrils in the airway mucosa and were rapidly killed by membrane destabilization. The significance in host-pathogen interplay of one of these molecules, PE, was highlighted by the observation that it confers partial protection from bacterial killing. Bacteria lacking PE were more prone to antimicrobial activity than NTHi expressing PE. Altogether the data shed new light on the carefully orchestrated molecular events of the host-pathogen interplay in COPD and emphasize the importance of the extracellular matrix as a novel branch of innate host defense.
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| 7. |
- Laabei, Maisem, et al.
(författare)
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Short leucine-rich proteoglycans modulate complement activity and increase killing of the respiratory pathogen moraxella catarrhalis
- 2018
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 201:9, s. 2721-2730
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Tidskriftsartikel (refereegranskat)abstract
- The respiratory pathogen Moraxella catarrhalis is a human-specific commensal that frequently causes acute otitis media in children and stimulates acute exacerbations in chronic obstructive pulmonary disease patients. The exact molecular mechanisms defining host-pathogen interactions promoting pathogenesis are not clearly understood. Limited knowledge hampers vaccine and immunotherapeutic development required to treat this emerging pathogen. In this study, we reveal in detail a novel antibacterial role displayed by short leucine-rich proteoglycans (SLRPs) in concert with complement. We show that fibromodulin (FMOD), osteoadherin (OSAD), and biglycan (BGN) but not decorin (DCN) enhance serum killing of M. catarrhalis. Our results suggest that M. catarrhalis binding to SLRPs is a conserved feature, as the overwhelming majority of clinical and laboratory strains bound all four SLRPs. Furthermore, we resolve the binding mechanism responsible for this interaction and highlight the role of the ubiquitous surface protein (Usp) A2/A2H in mediating binding to host SLRPs. A conserved immune evasive strategy used by M. catarrhalis and other pathogens is the surface acquisition of host complement inhibitors such as C4b-binding protein (C4BP). We observed that FMOD, OSAD, and BGN competitively inhibit binding of C4BP to the surface of M. catarrhalis, resulting in increased C3b/iC3b deposition, membrane attack complex (MAC) formation, and subsequently decreased bacterial survival. Furthermore, both OSAD and BGN promote enhanced neutrophil killing in vitro, both in a complement-dependent and independent fashion. In summary, our results illustrate that SLRPs, FMOD, OSAD, and BGN portray complement-modulating activity enhancing M. catarrhalis killing, defining a new antibacterial role supplied by SLRPs.
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| 8. |
- Riesbeck, Kristian, et al.
(författare)
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Evidence that the antibiotic ciprofloxacin counteracts cyclosporine‐dependent suppression of cytokine production
- 1994
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Ingår i: Transplantation. - : Ovid Technologies (Wolters Kluwer Health). - 0041-1337. ; 57:2, s. 267-272
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Tidskriftsartikel (refereegranskat)abstract
- The fluoroquinolone antibiotic ciprofloxacin (cipro) has been reported to upregulate interleukin 2 and interferon-γ production in lectin-stimulated lymphocytes. The aim of this study was to elucidate whether cipro and the immunosuppressive agent CsA have antagonistic action on cytokine synthesis. Accumulation of IL-2 and IFN-γ protein and mRNA were analyzed in polyclonally (PHA or Con A) or alloantigen-stimulated human peripheral blood lymphocytes. CsA added simultaneously with PHA partially blocked cytokine synthesis. The present study also shows that cipro supplemented with CsA and PHA resulted in significant higher concentrations of IL-2 (up to 60 times) and IFN-γ (4.3 times) as compared with PHA and CsA alone. Similar results were obtained with primary mixed lymphocyte reactions. In parallel, a greater amount of IL-2 and IFN-γ mRNA was observed in lymphocytes incubated with both cipro and CsA as compared with CsA alone. Our results reveal that CsA-dependent inhibition of both IL-2 and IFN-γ expression is counteracted by high concentrations of cipro. These findings may be of importance in clinical transplantation.
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| 9. |
- Su, Yu Ching, et al.
(författare)
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The interplay between immune response and bacterial infection in COPD : Focus Upon non-typeable Haemophilus influenzae
- 2018
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Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 9:NOV
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Forskningsöversikt (refereegranskat)abstract
- Chronic obstructive pulmonary disease (COPD) is a debilitating respiratory disease and one of the leading causes of morbidity and mortality worldwide. It is characterized by persistent respiratory symptoms and airflow limitation due to abnormalities in the lower airway following consistent exposure to noxious particles or gases. Acute exacerbations of COPD (AECOPD) are characterized by increased cough, purulent sputum production, and dyspnea. The AECOPD is mostly associated with infection caused by common cold viruses or bacteria, or co-infections. Chronic and persistent infection by nontypeable Haemophilus influenzae (NTHi), a Gram-negative coccobacillus, contributes to almost half of the infective exacerbations caused by bacteria. This is supported by reports that NTHi is commonly isolated in the sputum from COPD patients during exacerbations. Persistent colonization of NTHi in the lower airway requires a plethora of phenotypic adaptation and virulent mechanisms that are developed over time to cope with changing environmental pressures in the airway such as host immuno-inflammatory response. Chronic inhalation of noxious irritants in COPD causes a changed balance in the lung microbiome, abnormal inflammatory response, and an impaired airway immune system. These conditions significantly provide an opportunistic platform for NTHi colonization and infection resulting in a “vicious circle.” Episodes of large inflammation as the consequences of multiple interactions between airway immune cells and NTHi, accumulatively contribute to COPD exacerbations and may result in worsening of the clinical status. In this review, we discuss in detail the interplay and crosstalk between airway immune residents and NTHi, and their effect in AECOPD for better understanding of NTHi pathogenesis in COPD patients.
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| 10. |
- Dieudonné-Vatran, Antoine, et al.
(författare)
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Clinical isolates of Streptococcus pneumoniae bind the complement inhibitor C4b-binding protein in a PspC allele-dependent fashion.
- 2009
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 1550-6606 .- 0022-1767. ; 182:12, s. 7865-7877
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Tidskriftsartikel (refereegranskat)abstract
- The complement system constitutes an important component of the innate immune system. To colonize their host and/or to cause disease, many pathogens have evolved strategies to avoid complement-mediated bacterial lysis and opsonophagocytosis. In this study, using a collection of 55 clinical isolates of Streptococcus pneumoniae, we demonstrate for the first time that pneumococci bind the complement inhibitor C4b-binding protein (C4BP). C4BP binding seems to be restricted to certain serotypes such as serotype 4, 6B, 7F, and 14, of which the strains of serotype 14 are the strongest binders. We show that bacteria-bound C4BP retains its functional activity and down-regulates the activation of the classical pathway. Thus, this major respiratory pathogen may escape immune recognition and eradication by the complement system. Furthermore, we show that C4BP binding varies between strains but is dependent on the expression of pneumococcal surface protein C, PspC of group 4. The study of the distribution of group 4 pspC locus shows that most of high-binder serotype 14 isolates harbor an allelic variant of group 4 pspC. Using PspC-negative mutant strains, we identified a new allelic variant of PspC (PspC4.4) as a major ligand for C4BP, revealing a new function for this important pneumococcal virulence factor. Thus pneumococci exploit host C4BP for complement evasion in a PspC allele-dependent manner.
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