Biology subjects

Dufort, M. J.

Publications and source records attributed to Dufort, M. J..

3 recordsLinked to original sources

bioRxiv2025

Hypoxia-inducible factor 2α promotes protective Th2 cell responses during intestinal helminth infection

Th2 cells must sense and adapt to the tissue milieu in order to provide protective host immunity and tissue repair. Here, we examined the mechanisms promoting Th2 cell differentiation and function within the small intestinal lamina propria. Single cell RNA-seq analyses of CD4+ T cells from the small intestinal lamina propria of helminth infected mice revealed high expression of the gene Epas1, encoding the transcription factor hypoxia-inducible factor 2a (HIF2). In vitro, exposure to hypoxia or genetic HIF2 activation promoted Th2 cell differentiation, even under non-polarizing conditions. In mice, HIF2 activation in CD4+ T cells promoted intestinal Th2 cell accumulation in the absence of infection, and HIF2-deficiency impaired CD4+ T cell-mediated host immunity to intestinal helminth infection. Our findings identified hypoxia, and the oxygen-regulated transcription factor Hypoxia-Inducible Factor 2 (HIF2), as key regulators of Th2 cell differentiation and function within the small intestine.

immunology↗

bioRxiv2023

Antigen-level resolution of commensal-specific B cell responses enabled by phage-display screening and B cell tetramers

Induction of adaptive immune responses to commensal microbes is critical for tissue homeostasis, and perturbation of these responses is associated with multiple chronic inflammatory disorders. However, the mechanisms underlying the induction and regulation of mucosal B cells targeting commensal microbes remain poorly understood, in part due to a lack of tools to identify commensal-specific B cells ex vivo. To address this, we identified immunogenic protein epitopes recognized by Segmented Filamentous Bacteria (SFB)-specific serum antibodies using a whole-genome phage display screen and identified immunogenic proteins engaging IgA, IgG1 and IgG2b responses. Using these antigens, we generated B cell tetramers to identify and track SFB-specific B cell responses in the gut associated lymphoid tissue during natural and de novo colonization. We revealed a compartmentalized response in SFB-specific B cell activation between Peyers patches and mesenteric lymph nodes, with a gradient of IgA, IgG1 and IgG2b isotypes along the small intestine, and selective production of IgG2b with the mesenteric lymph node chain. VDJ sequencing analyses and generation of SFB-specific monoclonal antibodies identified that somatic hypermutation drives affinity maturation to SFB derived antigens under homeostatic conditions. By combining phage display screening and B cell tetramer technologies, we now enable antigen-level based studies of immunity to intestinal microbes, which will advance our understanding of the ontogeny and function of commensal-specific B cell responses in tissue immunity, inflammation and repair.

immunology↗

bioRxiv2023

Lupus IgA1 autoantibodies synergize with IgG to enhance plasmacytoid dendritic cell responses to RNA-containing immune complexes

Autoantibodies to nuclear antigens are hallmarks of the autoimmune disease systemic lupus erythematosus (SLE) where they contribute to pathogenesis. However, there remains a gap in our knowledge regarding how different isotypes of autoantibodies contribute to disease, including the production of the critical type I interferon (IFN) cytokines by plasmacytoid dendritic cells (pDCs) in response to immune complexes (ICs). We focused on IgA, which is the second most prevalent isotype in serum, and along with IgG is deposited in glomeruli in lupus nephritis. Here, we show that individuals with SLE have IgA autoantibodies against most nuclear antigens, correlating with IgG against the same antigen. We investigated whether IgA autoantibodies against a major SLE autoantigen, Smith ribonucleoproteins (Sm/RNPs), play a role in IC activation of pDCs. We found that pDCs express the IgA-specific Fc receptor, FcR, and there was a striking ability of IgA1 autoantibodies to synergize with IgG in RNA-containing ICs to generate robust pDC IFN responses. pDC responses to these ICs required both FcR and Fc{gamma}RIIa, showing a potent synergy between these Fc receptors. Sm/RNP IC binding to and internalization by pDCs were greater when ICs contained both IgA1 and IgG. pDCs from individuals with SLE had higher binding of IgA1-containing ICs and higher expression of FcR than pDCs from healthy control individuals. Whereas pDC FcR expression correlated with blood ISG signature in SLE, TLR7 agonists, but not IFN, upregulated pDC FcR expression in vitro. Together, we show a new mechanism by which IgA1 autoantibodies contribute to SLE pathogenesis. One Sentence SummaryIgA1 autoantibodies synergize with IgG in RNA-containing immune complexes to generate robust pDC IFN responses in a FcR receptor dependent manner.

immunology↗