Secretory IgA binding to FCRL3 triggers shared inflammatory cytokine secretion by human regulatory T cells and

Zachary Kraus1, Shama Birla2, Taylor Powell2

  • 1Office of Pharmaceutical Quality Assessment III, CDER, U.S. Food and Drug Administration, 10903 New Hampshire Ave, Silver Spring, MD 20993, USA.

PubMed

Several human lymphocyte subsets express the novel secretory IgA receptor FCRL3 (Fc receptor-like 3). Secretory IgA binding to FCRL3 diminishes the inhibitory capacity of regulatory T cells and promotes a T helper 17-like phenotype. Here, we report that in CD4+ regulatory T cells and CD8+ terminal effector T cells secretory IgA induced a shared inflammatory gene signature that included PTGS2 encoding COX2, and the prototypic inflammatory cytokine genes IL1A, IL1B, and IL8. Secretory IgA in regulatory T cells also elevated gene transcripts required for lineage identity and function. Secretory IgA promoted interleukin (IL)-1β, IL-6, IL-8, IL-10, interferon γ, and tumor necrosis factor α protein secretion by both T cell types. Moreover, secretory IgA promoted NLRP3 inflammasome activation in regulatory T cells. Pharmacologic COX2 and NLRP3 inhibitors partially rescued the inhibitory competence of regulatory T cells, suggesting respective mechanistic roles. We propose that secretory IgA provokes a coordinated inflammatory response in regulatory and effector T cells to facilitate mucosal pathogen clearance.

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