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| 2. |
- Lin, Xionghui, et al.
(författare)
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Transglutaminase activity in the hematopoietic tissue of a crustacean, Pacifastacus leniusculus, importance in hemocyte homeostasis
- 2008
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Ingår i: BMC Immunology. - : Springer Science and Business Media LLC. - 1471-2172. ; 9:58, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Transglutaminases (TGases) form a group of enzymes that have many different substrates and among the most well known are fibrin for Factor XIIIa and the clotting protein in crustaceans. We also found that TGase is an abundant protein in the hematopoietic tissue (Hpt) cells of crayfish and hence we have studied the possible function of this enzyme in hematopoiesis. RESULTS: TGase is one of the most abundant proteins in the Hpt and its mRNA expression as well as enzyme activity is very high in the Hpt cells, lesser in the semi-granular hemocytes and very low in the granular cells. In cultured hematopoietic tissues, high activity was present in cells in the centre of the tissue, whereas cells migrating out of the tissue had very low TGase activity. RNAi experiments using dsRNA for TGase completely knocked down the transcript and as a result the cell morphology was changed and the cells started to spread intensely. If astakine, a cytokine directly involved in hematopoiesis, was added the cells started to spread and adopt a morphology similar to that observed after RNAi of TGase. Astakine had no effect on TGase expression, but after a prolonged incubation for one week with this invertebrate cytokine, TGase activity inside and outside the cells was completely lost. Thus it seems as if astakine addition to the Hpt cells and RNAi of TGase in the cell culture will lead to the same results, i.e. loss of TGase activity in the cells and they start to differentiate and spread. CONCLUSION: The results of this study suggest that TGase is important for keeping the Hpt cells in an undifferentiated stage inside the hematopoietic tissue and if expression of TGase mRNA is blocked the cells start to differentiate and spread. This shows a new function for transglutaminase in preventing hematopoietic stem cells from starting to differentiate and migrate into the hemolymph, whereas their proliferation is unaffected. Astakine is also important for the hematopoiesis, since it induces hemocyte synthesis in the Hpt but now we also show that it in some unknown way participates in the differentiation of the Hpt cells.
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| 3. |
- Gustafsson, Erika, et al.
(författare)
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Identification of conformational epitopes for human IgG on chemotaxis inhibitory protein of Staphylococcus aureus
- 2009
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Ingår i: BMC Immunology. - : Springer Science and Business Media LLC. - 1471-2172. ; 10:13
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Tidskriftsartikel (refereegranskat)abstract
- Background The Chemotaxis inhibitory protein of Staphylococcus aureus (CHIPS) blocks the Complement fragment C5a receptor (C5aR) and formylated peptide receptor (FPR) and is thereby a potent inhibitor of neutrophil chemotaxis and activation of inflammatory responses. The majority of the healthy human population has antibodies against CHIPS that have been shown to interfere with its function in vitro. The aim of this study was to define potential epitopes for human antibodies on the CHIPS surface. We also initiate the process to identify a mutated CHIPS molecule that is not efficiently recognized by preformed anti-CHIPS antibodies and retains anti-inflammatory activity. Results In this paper, we panned peptide displaying phage libraries against a pool of CHIPS specific affinity-purified polyclonal human IgG. The selected peptides could be divided into two groups of sequences. The first group was the most dominant with 36 of the 48 sequenced clones represented. Binding to human affinity-purified IgG was verified by ELISA for a selection of peptide sequences in phage format. For further analysis, one peptide was chemically synthesized and antibodies affinity-purified on this peptide were found to bind the CHIPS molecule as studied by ELISA and Surface Plasmon Resonance. Furthermore, seven potential conformational epitopes responsible for antibody recognition were identified by mapping phage selected peptide sequences on the CHIPS surface as defined in the NMR structure of the recombinant CHIPS31-121 protein. Mapped epitopes were verified by in vitro mutational analysis of the CHIPS molecule. Single mutations introduced in the proposed antibody epitopes were shown to decrease antibody binding to CHIPS. The biological function in terms of C5aR signaling was studied by flow cytometry. A few mutations were shown to affect this biological function as well as the antibody binding. Conclusions Conformational epitopes recognized by human antibodies have been mapped on the CHIPS surface and amino acid residues involved in both antibody and C5aR interaction could be defined. This information has implications for the development of an effective anti-inflammatory agent based on a functional CHIPS molecule with low interaction with human IgG.
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| 4. |
- Kolbus, Daniel, et al.
(författare)
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CD8+ T cell activation predominate early immune responses to hypercholesterolemia in Apoe-/- mice.
- 2010
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Ingår i: BMC Immunology. - : Springer Science and Business Media LLC. - 1471-2172. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- It is well established that adaptive immune responses induced by hypercholesterolemia play an important role in the development of atherosclerosis, but the pathways involved remain to be fully characterized. In the present study we assessed immune responses to hypercholesterolemia induced by feeding Apoe-/- mice a high-fat diet for 4 or 8 weeks.
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| 5. |
- Källberg, Eva, et al.
(författare)
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CD11b(+)Ly6C(++)Ly6G(-) cells show distinct function in mice with chronic inflammation or tumor burden
- 2012
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Ingår i: BMC Immunology. - : Springer Science and Business Media LLC. - 1471-2172. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Background: S100A9 has been shown to be important for the function of so called Myeloid Derived Suppressor Cells (MDSC). Cells with a similar phenotype are also involved in pro-inflammatory processes, and we therefore wanted to investigate the gene expression and function of these cells in animals that were either subjected to chronic inflammation, or inoculated with tumors. Methods: CD11b(+)Ly6C(++) and Ly6G(+) cells were isolated from spleen, tumor tissue or inflammatory granulomas. S100A9, Arginase 1 and iNOS gene expression in the various CD11b(+) cell populations was analyzed using Q-PCR. The suppressive activity of the CD11b(+) cell populations from different donors was studied in co-culture experiments. Results: S100A9 was shown to be expressed mainly in splenic CD11b(+)Ly6C(+)G(+) cells both at the RNA and protein level. Arginase I and iNOS expression could be detected in both CD11b(+)Ly6C(+)Ly6G(+) and CD11b(+)Ly6C(+)G(-)/C(++)G(-) derived from tumors or a site of chronic inflammation, but was very low in the same cell populations isolated from the spleen. CD11b(+) cells isolated from mice with peritoneal chronic inflammation were able to stimulate T lymphocytes, while CD11b(+) cells from mice with peritoneal tumors suppressed T cell growth. Conclusion: An identical CD11b(+)Ly6C(++)G(-) cell population appears to have the ability to adopt immune stimulatory or immune suppressive functions dependent on the presence of a local inflammatory or tumor microenvironment. Thus, there is a functional plasticity in the CD11b(+)Ly6C(++)G(-) cell population that cannot be distinguished with the current molecular markers.
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| 6. |
- Martini, Paolo G. V., et al.
(författare)
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Recombinant human complement component C2 produced in a human cell line restores the classical complement pathway activity in-vitro: an alternative treatment for C2 deficiency diseases
- 2010
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Ingår i: BMC Immunology. - : Springer Science and Business Media LLC. - 1471-2172. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Background: Complement C2 deficiency is the most common genetically determined complete complement deficiency and is associated with a number of diseases. Most prominent are the associations with recurrent serious infections in young children and the development of systemic lupus erythematosus (SLE) in adults. The links with these diseases reflect the important role complement C2 plays in both innate immunity and immune tolerance. Infusions with normal fresh frozen plasma for the treatment of associated disease have demonstrated therapeutic effects but so far protein replacement therapy has not been evaluated. Results: Human complement C2 was cloned and expressed in a mammalian cell line. The purity of recombinant human C2 (rhC2) was greater than 95% and it was characterized for stability and activity. It was sensitive to C1s cleavage and restored classical complement pathway activity in C2-deficient serum both in a complement activation ELISA and a hemolytic assay. Furthermore, rhC2 could increase C3 fragment deposition on the human pathogen Streptococcus pneumoniae in C2-deficient serum to levels equal to those with normal serum. Conclusions: Taken together these data suggest that recombinant human C2 can restore classical complement pathway activity and may serve as a potential therapeutic for recurring bacterial infections or SLE in C2-deficient patients.
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| 7. |
- Persson, Jenny, et al.
(författare)
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Interleukin-1 beta and tumour necrosis factor-alpha impede neutral lipid turnover in macrophage-derived foam cells
- 2008
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Ingår i: BMC Immunology. - : Springer Science and Business Media LLC. - 1471-2172. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Background: Pro-inflammatory cytokines can affect intracellular lipid metabolism. A variety of effects have been described for different cell types; hepatocyte lipid turnover pathways are inhibited during inflammation, whereas interleukin-1 beta (IL-1 beta) reduces intracellular cholesterol levels in fibroblasts. Levels of the pro-inflammatory cytokines IL-1 beta and tumour necrosis factor-alpha (TNF-alpha) are up-regulated at sites of formation of atherosclerotic plaques. Plaque formation is though to begin with infiltration of monocytes to the intimal layer of the vascular wall, followed by differentiation to macrophages and macrophage uptake of modified lipoproteins, resulting in accumulation of intracellular lipids. The lipid-filled cells are referred to as macrophage foam cells, a key feature of atherosclerotic plaques. We have investigated the effects of IL-1 beta and TNF-alpha on macrophage foam cells in order to assess whether presence of the pro-inflammatory cytokines improves or aggravates macrophage foam cell formation by affecting lipid accumulation and lipid turn-over in the cells. Results: Differentiated primary human macrophages or THP-1 cells were lipid loaded by uptake of aggregated low density lipoproteins (AgLDL) or very low density lipoproteins (VLDL), and then incubated with IL-1 beta (0-5000 pg/ml) in lipoprotein-free media for 24 h. Cells incubated in absence of cytokine utilized accumulated neutral lipids, in particular triglycerides. Addition of exogenous IL-1 beta resulted in a dose-dependent retention of intracellular cholesterol and triglycerides. Exchanging IL-1 beta with TNF-alpha gave a similar response. Analysis of fatty acid efflux and intracellular fatty acid activation revealed a pattern of decreased lipid utilization in cytokine-stimulated cells. Conclusion: IL-1 alpha and TNF-alpha enhance macrophage foam cell formation, in part by inhibition of macrophage intracellular lipid catabolism. If present in vivo, these mechanisms will further augment the pro-atherogenic properties of the two cytokines.
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| 8. |
- Benedict, Christian, et al.
(författare)
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Acute sleep deprivation has no lasting effects on the human antibody titer response following a novel influenza A H1N1 virus vaccination
- 2012
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Ingår i: BMC Immunology. - : Springer Science and Business Media LLC. - 1471-2172. ; 13, s. 1-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Experimental studies in humans have yielded evidence that adaptive immune function, including the production of antigen-specific antibodies, is distinctly impaired when sleep is deprived at the time of first antigen exposure. Here we examined the effects of a regular 24- hour sleep-wake cycle (including 8 hours of nocturnal sleep) and a 24-hour period of continuous wakefulness on the 7 week antibody production in 11 males and 13 females in response to the H1N1 (swine flu) virus vaccination. The specific antibody titer in serum was assayed by the hemagglutination inhibition test on the days 5, 10, 17, and 52 following vaccination.Results: In comparison to the sleep group, sleep-deprived males but not females had reduced serum concentration of H1N1-specific antibodies five days after vaccination, whereas antibody titers at later time points did not differ between the conditions.Conclusions: These findings concur with the notion that sleep is a supportive influence in the very early stage of an adaptive immune response to a viral antigen. However, our results do not support the view that acute sleep deprivation has lasting effects on the human antibody titer response to influenza vaccination.
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| 9. |
- Costa, Ivan G, et al.
(författare)
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Gene expression trees in lymphoid development.
- 2007
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Ingår i: BMC immunology. - : Springer Science and Business Media LLC. - 1471-2172. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The regulatory processes that govern cell proliferation and differentiation are central to developmental biology. Particularly well studied in this respect is the lymphoid system due to its importance for basic biology and for clinical applications. Gene expression measured in lymphoid cells in several distinguishable developmental stages helps in the elucidation of underlying molecular processes, which change gradually over time and lock cells in either the B cell, T cell or Natural Killer cell lineages. Large-scale analysis of these gene expression trees requires computational support for tasks ranging from visualization, querying, and finding clusters of similar genes, to answering detailed questions about the functional roles of individual genes.We present the first statistical framework designed to analyze gene expression data as it is collected in the course of lymphoid development through clusters of co-expressed genes and additional heterogeneous data. We introduce dependence trees for continuous variates, which model the inherent dependencies during the differentiation process naturally as gene expression trees. Several trees are combined in a mixture model to allow inference of potentially overlapping clusters of co-expressed genes. Additionally, we predict microRNA targets.Computational results for several data sets from the lymphoid system demonstrate the relevance of our framework. We recover well-known biological facts and identify promising novel regulatory elements of genes and their functional assignments. The implementation of our method (licensed under the GPL) is available at http://algorithmics.molgen.mpg.de/Supplements/ExpLym/.
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| 10. |
- Gustafsson, Karin, et al.
(författare)
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Shb deficient mice display an augmented TH2 response in peripheral CD4+ T cells
- 2011
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Ingår i: BMC Immunology. - : Springer Science and Business Media LLC. - 1471-2172. ; 12, s. 3-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Shb, a ubiquitously expressed Src homology 2 domain-containing adaptor protein has previously been implicated in the signaling of various tyrosine kinase receptors including the TCR. Shb associates with SLP76, LAT and Vav, all important components in the signaling cascade governing T cell function and develeopment. A Shb knockout mouse was recently generated and the aim of the current study was to address the importance of Shb deficiency on T cell development and function. Results: Shb knockout mice did not display any major changes in thymocyte development despite an aberrant TCR signaling pattern, including increased basal activation and reduced stimulation-induced phosphorylation. The loss of Shb expression did however affect peripheral CD4+ TH cells resulting in an increased proliferative response to TCR stimulation and an elevated IL-4 production level of naïve TH cells. This suggests a TH2 skewing of the Shb knockout immune system, seemingly caused by an altered TCR signaling pattern.Conclusion: Our results indicate that Shb appears to play an important modulating role on TCR signaling, thus regulating the peripheral CD4+ TH2 cell response.
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