Date: Sunday, November 8, 2020
Session Type: Poster Session C
Session Time: 9:00AM-11:00AM
Background/Purpose: Mutations in nucleotide-binding oligomerization domain-containing protein 2 (NOD2) cause Blau syndrome, an inflammatory disorder characterized by uveitis, dermatitis, and polyarthritis. The antimicrobial functions of NOD2 are well established; yet the mechanism by which dysregulated NOD2 causes sterile inflammation remain unknown. Here we utilized experimental models of autoimmune arthritis and uveitis, and PBMCs from Blau syndrome patients to dissect a T cell-specific role for NOD2 in uveitis.
Methods: Arthritis was induced in SKG and NOD2-/-SKG mice with a single intraperitoneal 1.5mg injection of zymosan and assessed by clinical scoring, near infrared imaging and histology. Uveitis was induced in NOD2+/+ and NOD2-/- C57BL/6 mice by immunization with the retinal antigen interphotoreceptor retinoid-binding protein (IRBP) and assessed by clinical scoring and histology. Mice were treated with IL-17A/F mAb (R&D systems) beginning 24h prior to disease induction. Lymphopenic Rag1-/- mice were reconstituted with NOD2-/- or NOD2+/+ (WT) CD4+ T cells and arthritis or uveitis was induced. IL-17 production by T cells was evaluated by flow cytometry and ELISA. For T cell homeostasis studies, purified naive (CD62LhiCD44–) CD4+ T cells were differentiated under Th17 polarizing conditions (CellXVivo) or purified memory (CD62L–CD44hi) CD4+ T cells from naive mice were stimulated with anti-CD3 and anti-CD28, and activation state (CD69) and pro-inflammatory cytokine production was determined by flow cytometry (n≥6 mice/group and repeated 3X). Peripheral blood mononuclear cells from Blau Syndrome patients or healthy controls were cultured for 5 d, stimulated with PMA/ionomycin, and IL-17 was measured. Data were analyzed by Mann-Whitney, and p< 0.05 were considered significant.
Results: Lymphopenic recipients of NOD2-deficient T cells developed significantly worse arthritis and uveitis, implicating T cell-intrinsic NOD2 in suppression of disease. CD4+ T cells purified from arthritic and uveitic mice produced significantly more IL-17, and blockade of IL-17 mitigated the enhanced disease caused by NOD2-deficiency, indicating a direct role for T cell-intrinsic NOD2 in suppressing autoreactive Th17 responses. NOD2 was dispensable for Th17 differentiation of naïve CD4+ T cells. However, NOD2-/- memory (antigen-experienced) CD4+ T cells isolated from naïve mice when stimulated with anti-CD3 and anti-CD28 had enhanced expression of IL-17, the IL-17-associated transcription factor (RORγt) and the activation marker CD69. Importantly, stimulation of CD4+ T cells from Blau syndrome patients resulted in significantly more IL-17 production than those from healthy control T cells, suggesting a similar function for NOD2 in human disease.
Conclusion: We have uncovered a novel, T cell-intrinsic function for NOD2 as a negative regulator of T cell homeostasis and autoimmunity. Our work suggests that a “loss-of-function” in NOD2 (i.e. NOD2-/- mice) results in a “gain-of-function” in the ability of T cells to produce IL-17 and cause arthritis and uveitis. These findings could potentially change the way we view the immunopathology of Blau syndrome and open up new therapeutic options for patients.
To cite this abstract in AMA style:Napier R, Lee E, Vance E, Lashley S, Uebelhoer L, Lancioni C, Vehe R, Binstadt B, Caspi R, Rosenzweig H. A T Cell Intrinsic Role for Nod2 in Suppression of Th17-Mediated Experimental Arthritis and Uveitis: Implications for Blau Syndrome [abstract]. Arthritis Rheumatol. 2020; 72 (suppl 10). https://acrabstracts.org/abstract/a-t-cell-intrinsic-role-for-nod2-in-suppression-of-th17-mediated-experimental-arthritis-and-uveitis-implications-for-blau-syndrome/. Accessed January 22, 2021.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-t-cell-intrinsic-role-for-nod2-in-suppression-of-th17-mediated-experimental-arthritis-and-uveitis-implications-for-blau-syndrome/