| 1. |
- Urrutia-Cordero, Pablo, et al.
(författare)
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Effects of harmful cyanobacteria on the freshwater pathogenic free-living amoeba Acanthamoeba castellanii
- 2013
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Ingår i: Aquatic Toxicology. - : Elsevier. - 0166-445X .- 1879-1514. ; 130, s. 9-17
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Tidskriftsartikel (refereegranskat)abstract
- Grazing is a major regulating factor in cyanobacterial population dynamics and, subsequently, considerable effort has been spent on investigating the effects of cyanotoxins on major metazoan grazers. However, protozoan grazers such as free-living amoebae can also feed efficiently on cyanobacteria, while simultaneously posing a major threat for public health as parasites of humans and potential reservoirs of opportunistic pathogens. In this study, we conducted several experiments in which the freshwater amoeba Acanthamoeba castellanii was exposed to pure microcystin-LR (MC-LR) and six cyanobacterial strains, three MC-producing strains (MC-LR, MC-RR, MC-YR, MC-WR, [Dha7] MC-RR) and three strains containing other oligopeptides such as anabaenopeptins and cyanopeptolins. Although the exposure to high concentrations of pure MC-LR yielded no effects on amoeba, all MC-producing strains inflicted high mortality rates on amoeba populations, suggesting that toxic effects must be mediated through the ingestion of toxic cells. Interestingly, an anabaenopeptin-producing strain caused the greatest inhibition of amoeba growth, indicating that toxic bioactive compounds other than MCs are of great importance for amoebae grazers. Confocal scanning microscopy revealed different alterations in amoeba cytoskeleton integrity and as such, the observed declines in amoeba densities could have indeed been caused via a cascade of cellular events primarily triggered by oligopeptides with protein-phosphatase inhibition capabilities such as MCs or anabaenopeptins. Moreover, inducible-defense mechanisms such as the egestion of toxic, MC-producing cyanobacterial cells and the increase of resting stages (encystation) in amoebae co-cultivated with all cyanobacterial strains were observed in our experiments. Consequently, cyanobacterial strains showed different susceptibilities to amoeba grazing which were possibly influenced by the potentiality of their toxic secondary metabolites. Hence, this study shows the importance of cyanobacterial toxicity against amoeba grazing and, that cyanobacteria may contain a wide range of chemical compounds capable of negatively affect free-living, herbivorous amoebae. Moreover, this is of high importance for understanding the interactions and population dynamics of such organisms in aquatic ecosystems. (c) 2012 Elsevier B.V. All rights reserved.
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| 2. |
- Teneberg, Susanne, et al.
(författare)
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Lactotetraosylceramide, a novel glycosphingolipid receptor for Helicobacter pylori, present in human gastric epithelium
- 2002
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Ingår i: Journal of Biological Chemistry. - Bethesda : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 277:22, s. 19709-19719
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Tidskriftsartikel (refereegranskat)abstract
- The binding of Helicobacter pylori to glycosphingolipids was examined by binding of 35S-labeled bacteria to glycosphingolipids on thin-layer chromatograms. In addition to previously reported binding specificities, a selective binding to a non-acid tetraglycosylceramide of human meconium was found. This H. pylori binding glycosphingolipid was isolated and, on the basis of mass spectrometry, proton NMR spectroscopy, and degradation studies, were identified as Galβ3GlcNAcβ3-Galβ4Glcβ1Cer (lactotetraosylceramide). When using non-acid glycosphingolipid preparations from human gastric epithelial cells, an identical binding of H. pylori to the tetraglycosylceramide interval was obtained in one of seven samples. Evidence for the presence of lactotetraosylceramide in the binding-active interval was obtained by proton NMR spectroscopy of intact glycosphingolipids and by gas chromatography-electron ionization mass spectrometry of permethylated tetrasaccharides obtained by ceramide glycanase hydrolysis. The lactotetraosylceramide binding property was detected in 65 of 74 H. pylori isolates (88%) Binding of H. pylori to lactotetraosylceramide on thin-layer chromatograms was inhibited by preincubation with lactotetraose but not with lactose. Removal of the terminal galactose of lactotetraosylceramide by galactosidase hydrolysis abolished the binding as did hydrazinolysis of the acetamido group of the N-acetylglucosamine. Therefore, Galβ3GlcNAc is an essential part of the binding epitope.
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| 3. |
- Löfström, Emma, et al.
(författare)
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Dynamics of IgG-avidity and antibody levels after Covid-19
- 2021
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Ingår i: Journal of Clinical Virology. - Amsterdam : Elsevier. - 1386-6532 .- 1873-5967. ; 144
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Tidskriftsartikel (refereegranskat)abstract
- Background: A potentially important aspect of the humoral immune response to Covid-19 is avidity, the overall binding strength between antibody and antigen. As low avidity is associated with a risk of re- infection in several viral infections, avidity might be of value to predict risk for reinfection with covid-19. Objectives: The purpose of this study was to describe the maturation of IgG avidity and the antibody-levels over time in patients with PCR-confirmed non-severe covid-19. Study design: Prospective longitudinal cohort study including patients with RT-PCR confirmed covid-19. Blood samples were drawn 1, 3 and 6 months after infection. Antibody levels and IgG-avidity were analysed. Results: The majority had detectable s- and n-antibodies (88,1%, 89,1%, N = 75). The level of total n-antibodies significantly increased from 1 to 3 months (median value 28,3 vs 39,3 s/co, p<0.001) and significantly decreased from 3 to 6 months (median value 39,3 vs 17,1 s/co, p<0.001). A significant decrease in the IgG anti-spike levels (median value 37,6, 24,1 and 18,2 RU/ml, p<0.001) as well as a significant increase in the IgG-avidity index (median values 51,6, 66,0 and 71,0%, p<0.001) were seen from 1 to 3 to 6 months. Conclusion: We found a significant ongoing increase in avidity maturation after Covid-19 whilst the levels of antibodies were declining, suggesting a possible aspect of long-term immunity. © 2021 The Authors. Published by Elsevier B.V.
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| 4. |
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| 5. |
- Fernström, Maria, 1960-, et al.
(författare)
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Improved Muscle Mitochondrial Capacity Following Gastric Bypass Surgery in Obese Subjects
- 2016
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Ingår i: Obesity Surgery. - New York, USA : Springer. - 0960-8923 .- 1708-0428. ; 26:7, s. 1391-1397
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Tidskriftsartikel (refereegranskat)abstract
- Background: Weight loss resulting from low-calorie diets is often less than expected. We hypothesized that energy restriction would influence proton leakage and improve mitochondrial efficiency, leading to reduced energy expenditure, partly explaining the difficulties in weight loss maintenance.Methods: Eleven women with a median BMI of 38.5 kg/m(2) (q-range 37-40), and referred to gastric bypass surgery participated. Before surgery, and at 6 months of follow-up, muscle biopsies were collected from the vastus lateralis muscle. Mitochondria were isolated and analyzed for coupled (state 3) and uncoupled (state 4) respiration and mitochondrial capacity (P/O ratio).Results: At follow-up, the participants had a median BMI of 29.6 kg/m(2) (28.3-32.0). State 3 increased from 20.6 (17.9-28.9) to 34.9 nmol O2/min/U citrate synthase (CS) (27.0-49.0), p = 0.01, while state 4 increased from 2.8 (1.8-4.2) to 4.2 nmol O2/min/U CS (3.1-6.1), although not statistically significant. The P/O ratio increased from 2.7 (2.5-2.8) to 3.2 (3.0-3.4), p = 0.02, indicating improved mitochondrial efficiency.Conclusions: Six months after gastric bypass surgery, the mitochondrial capacity for coupled, i.e., ATP-generating, respiration increased, and the P/O ratio improved. Uncoupled respiration was not enhanced to the same extent. This could partly explain the decreased basal metabolism and the reduced inclination for weight loss during energy restriction.
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| 6. |
- Wang, Tingting, et al.
(författare)
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Proteus mirabilis Vesicles Induce Mitochondrial Apoptosis by Regulating miR96-5p/Abca1 to Inhibit Osteoclastogenesis and Bone Loss
- 2022
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Ingår i: Frontiers in Immunology. - Lausanne : Frontiers Media S.A.. - 1664-3224. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Bone loss due to an increased osteoclast activity is common in osteoporosis and rheumatoid arthritis. For the first time, we observed an inhibition of osteoclast formation and bone resorption by outer-membrane vesicles (OMVs) from a Gram-negative, pathogenic bacterium, Proteus mirabilis (P.M). Gene ontogeny and KEGG enrichment analyses of miRNA and mRNA sequencing data demonstrated a significant effect of P.M OMVs on mitochondrial functions and apoptotic pathways. OMVs induced mitochondrial dysfunction through an increased level of intracellular ROS, collapse of mitochondrial membrane potential (ΔΨm), and modulation of Bax, Bcl-2, caspase-3, and cytochrome c expression. In addition, P.M OMVs strongly inhibited miR-96-5p expression, which caused an upregulation of ATP binding cassette subfamily A member 1 (Abca1) in osteoclasts leading to an increased level of mitochondria-dependent apoptosis. Moreover, treatment with P.M but not Escherichia coli OMVs attenuated bone loss in experimental osteoporosis and collagen-induced arthritis. Collectively, we demonstrated osteoprotective functions of OMVs from Proteus mirabilis, which downregulated miR-96-5p causing an increased Abca1 expression and mitochondria-dependent apoptosis. © 2022 Wang, Mo, Ou, Fang, Wu, Wu and Nandakumar.
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| 7. |
- Li, Yanpeng, et al.
(författare)
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Kaempferol modulates IFN-γ induced JAK-STAT signaling pathway and ameliorates imiquimod-induced psoriasis-like skin lesions
- 2023
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Ingår i: International Immunopharmacology. - London : Elsevier. - 1567-5769 .- 1878-1705. ; 114
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Tidskriftsartikel (refereegranskat)abstract
- Immune-mediated inflammation contributes to the development of psoriasis. However, long-term treatment with global immunosuppressive agents may cause a variety of side effects including recurrent infections. Kaempferol (KP), a natural flavonol, present in various plants is proposed to be useful for the treatment of psoriasis patients. Nevertheless, an explicit understanding of KP induced mechanisms is a prerequisite for its use in clinics. Therefore, we investigated the therapeutic effects and potential mode of action of KP using IFN-γ induced HaCaT cells and imiquimod-induced psoriasis-like skin lesions in mice. In this study, we found KP reduced intracellular ROS production, inhibited rhIFN-γ-induced IFN-γR1 expression, and up-regulated SOCS1 levels in HaCaT cells. In addition, KP inhibited rhIFN-γ-induced phosphorylation of JAK-STAT signaling molecules in HaCaT cells. Most importantly, KP alleviated imiquimod-induced psoriasis-like skin lesions in mice, histopathology and proportion of DCs in the skin. Besides, it reduced the population of γδT17 cells in the lymph nodes of the psoriatic mice and also decreased the gene expression of many proinflammatory cytokines, including interleukin IL-23, IL-17A, TNF-α, IL-6, and IL-1β in addition to down-regulation of the proinflammatory JAK-STAT signaling pathway. Thus, KP modulated IFN-γ induced JAK-STAT signaling pathway by inducing IFN-γR1 expression and up-regulating SOCS1 expression. In addition, KP also ameliorated imiquimod-induced psoriasis by reducing the dendritic cell numbers, and γδT17 cell population, along with down- modulation of the JAK-STAT pathway. © 2022 Elsevier B.V.
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| 8. |
- Muthukkaruppan, V. R., et al.
(författare)
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Monoclonal antibodies against Salmonella porins : generation and characterization
- 1992
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Ingår i: Immunology Letters. - Amsterdam : Elsevier. - 0165-2478 .- 1879-0542. ; 33:2, s. 201-206
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Tidskriftsartikel (refereegranskat)abstract
- Monoclonal antibodies (mAbs) were generated against porins, one of the major outer membrane proteins of Salmonella typhi. Six clones, designated MP1, MP2, MP3 (IgG2ak), MPN4, MPN6 (IgG1k) and MPN5 (IgG2bk) were characterized by enzyme immunoassay (ELISA) for their reactivity to porins from S. typhi, Salmonella paratyphi A, S. paratyphi B, S. paratyphi C, Salmonella choleraesuis, Salmonella enteritidis, Salmonella krefeld, Salmonella panama, Salmonella typhimurium, Escherichia coli B, Shigella flexneri 1b and Pseudomonas aeruginosa. All the clones positive for S. typhi porins showed varying reactivity towards several Salmonella species. However, none of them was positive for porins from other Gram-negative bacteria or for lipopolysaccharide (LPS). The affinity constant of these mAbs, except MPN4, was found to be in the higher range. Dot ELISA revealed that the mAbs recognized porins only in their native form. The results of inhibition ELISA using horseradish peroxidase (HRP)-conjugated MP1 suggest that the clones MP1, MP2, MP3, MPN5 and MPN6 secreted antibodies to identical epitope(s) of a 36-kDa peptide and MPN4 to a different epitope of a 35-kDa peptide. The possible applications of these mAbs were discussed.
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| 9. |
- Nandakumar, Kutty Selva, 1965-, et al.
(författare)
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Diagnosis of typhoid fever : detection of Salmonella typhi porins-specific antibodies by inhibition ELISA
- 1993
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Ingår i: Clinical and Experimental Immunology. - Chichester : Wiley-Blackwell Publishing Inc.. - 0009-9104 .- 1365-2249. ; 94:2, s. 317-321
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Tidskriftsartikel (refereegranskat)abstract
- Porins are highly immunogenic outer membrane proteins of Salmonella. Sera from typhoid patients contained a high level of IgG antibodies directed to porins of Salm. typhi. Since porins are highly conserved proteins, anti-porins antibodies both from typhoid patients and healthy normals reacted with porins from several Gram-negative bacteria. Therefore, in order to improve the specificity of detecting Salm. typhi porins-specific antibodies, an inhibition ELISA was developed using enzyme-conjugated MoAbs (MP1 and MPN4) specific to Salm. typhi porins. Sera from typhoid patients with positive haemoculture (16 out of 17) inhibited the binding of MP1 to porins, thus showing a positive test for typhoid, whereas sera from patients with other Gram-negative bacterial infections (n = 7) and from healthy volunteers (66 out of 67) were found to be negative. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of this assay were 94.1, 98.7, 97.8, 94.1 and 98.7% respectively. The validity of our inhibition ELISA for typhoid was higher than that of the Widal test. The diagnosis of typhoid fever as early as 3 days after the onset of fever, using a single specimen is possible.
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