Project description:We set up to characterize the global transcriptome of splenic follicular (FO) B cells from control wild type (Wt) and Igha-deficient (IgAKO) mice with the aim of gaining new insights into how translocated gut antigens may impair IgG production to vaccines in the absence of IgA. Splenic Marginal zone (MZ) B cells were also included in this study, as IgA deficiency impaired IgG responses to T-independent immunogens as well.
2024-01-01 | GSE173361 | GEO
Project description:Spink4 modulates gut microbiota to interfere IgA production
Project description:BackgroundThe imbalance of commensal bacteria is called dysbiosis in intestinal microflora. Secreted IgA in the intestinal lumen plays an important role in the regulation of microbiota. Although dysbiosis of gut bacteria is reported in IBD patients, it remains unclear what makes dysbiosis of their microflora. The intervention method for remedy of dysbiosis in IBD patients is not well established. In this study, we focused on the quality of human endogenous IgA and investigated whether mouse monoclonal IgA which binds to selectively colitogenic bacteria can modulate human gut microbiota with IBD patients.MethodsIgA-bound and -unbound bacteria were sorted by MACS and cell sorter. Sorted bacteria were analyzed by 16S rRNA sequencing to investigate what kinds of bacteria endogenous IgA or mouse IgA recognized in human gut microbiota. To evaluate the effect of mouse IgA, gnotobiotic mice with IBD patient microbiota were orally administrated with mouse IgA and analyzed gut microbiota.ResultsWe show that human endogenous IgA has abnormal binding activity to gut bacteria in IBD patients. Mouse IgA can bind to human microbiota and bind to selectively colitogenic bacteria. The rW27, especially, has a growth inhibitory activity to human colitogenic bacteria. Furthermore, oral administration of mouse IgA reduced an inflammation biomarker, fecal lipocalin 2, in mice colonized with IBD patient-derived microbiota, and improved dysbiosis of IBD patient sample.ConclusionOral treatment of mouse IgA can treat gut dysbiosis in IBD patients by modulating gut microbiota.
Project description:Immunoglobulin A (IgA)-producing plasma cells derived from conventional B cells in the gut play an important role in maintaining the homeostasis of gut flora. Both T cell-dependent and T cell-independent IgA class switching occurs in the lymphoid structures in the gut, whose formation depends on lymphoid tissue inducers (LTis), a subset of innate lymphoid cells (ILCs). However, our knowledge on the functions of ILCs, the innate counter parts of CD4 T helper cells, in promoting IgA production is still limited. By cell adoptive transfer and utilizing a unique mouse strain, we demonstrated that the generation of IgA-producing plasma cells from B cells in the gut occurred efficiently in the absence of both T cells and ILCs and without engaging TGFβ signaling. Nevertheless, B cell recruitment and/or retention in the gut required NKp46-CCR6+ LTis. Therefore, while ILCs contribute to the accumulation of B cells in the gut through inducing lymphoid structure formation, they are not essential for the T cell-independent generation of IgA-producing plasma cells.
Project description:IgA+ Plasma Cells were sort-purified from the small intestinal lamina prorpia of C57BL/6 mice at four Zeitgeber time points (ZT0, 6, 12 and 18). RNA extracted from these samples was subjected to bulk RNA seq to identify time of day differences in IgA+ PC gene expression.
Project description:Immunoglobulin A (IgA) is essential for mucosal immunity and is implicated in autoimmune diseases like IgA nephropathy (IgAN). Certain pathogenic and commensal bacteria produce IgA proteases (IgAPs) that selectively cleave IgA, potentially aiding bacterial colonization and offering therapeutic avenues for IgAN. Here, we investigate the substrate specificity of M64 family peptidases, focusing on the IgAP ThomasA from Thomasclavelia ramosa and BF3526 from Bacteroides fragilis. Structural, biochemical, and mutagenesis data demonstrate that ThomasA cleaves IgA through exclusive recognition of the Fab region—a mechanism distinct from other antibody-specific peptidases, which typically require engagement of the Fc region. In contrast, X-ray crystal structures of BF3526 in complex with substrate and product peptides, together with enzymology assays, show that this enzyme targets the N-terminus of predigested proteins. These findings reveal divergent substrate recognition strategies within the M64 family and provide structural insight into their conserved catalytic mechanism. Together, they enhance our understanding of bacterial adaptation and support the rational design of enzymes for IgA-mediated autoimmune diseases. The LC-MS data associated with the project is included in the current dataset.
Project description:To compare gene expression between CD11b+ IgA and CD11b- IgA cells in the small intestine, each cell population was isolated from the murine small intestine. Similar experiment with different sample was performed as described in Gene expression on CD11b+ IgA and CD11b- IgA cells in the small intestine #02