Prolonged IL-10 Exposure Modulates Adaptive and Innate Immune Responses in Secondary Lymphoid Organs during Experimental Autoimmune Encephalomyelitis 2332777

Abstract Introduction Interleukin-10 (IL-10) is a potent immunoregulatory cytokine that suppresses pro-inflammatory cytokine production, reduces antigen presentation by myeloid cells, promotes M2 macrophage polarization, and inhibits T cell activation. However, the clinical application of recombinant IL-10 is limited by its short plasma half-life and insufficient exposure in the secondary lymphoid organs (SLOs), key sites of autoreactive T cell priming in autoimmunity. Methods To address these limitations, we previously engineered a serum albumin-IL-10 fusion protein (SA-IL-10) with extended half-life and enhanced exposure in the SLOs. Here, using experimental autoimmune encephalomyelitis (EAE), a murine model of neuroinflammation, we subcutaneously administered SA-IL-10 and performed immunophenotyping in the SLOs and spinal cord to examine how sustained IL-10 exposure modulates immune responses under neuroinflammatory conditions. Results Immunophenotyping of the SLOs revealed that SA-IL-10 treatment reduced pathogenic, antigen-specific RORγt+ TH17 T cells, CD86+ M1-like macrophages, CD86+ dendritic cells and pro-inflammatory cytokine production, while expanding immunoregulatory CD206+ M2-like macrophages. Sustained IL-10 exposure expanded a novel checkpoint-high immunoregulatory TH2 phenotype, with GATA3+ TH2 cells expressing multiple immune checkpoint receptors, including CTLA-4, PD-1, TIGIT, and ICOS. Despite the absence of direct central nervous system targeting, SA-IL-10 treatment also reduced the infiltration of macrophages, dendritic cells, and CD4+ T cells in the spinal cord. Conclusion Together, these findings demonstrate that increasing IL-10 exposure in the SLOs alters peripheral immune priming and is associated with reduced pro-inflammatory immune cell infiltration in the spinal cord during EAE. Funding Source Alper Family Fund Grant (Awarded to Prof. Jeffrey A. Hubbell) Topic Categories Therapeutic Approaches to Autoimmunity (THER)