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bioRxiv · 10.1101/2022.07.28.501834

Deficiencies of Runx3 and tissue-resident CD4+ intestinal epithelial lymphocytes link intestinal dysbiosis and inflammation in mouse and human spondyloarthropathy

Bhuyan, Z.·Maradana, M.·Rahman, M. A.·Mehdi, A.·Bergot, A.-S.·Simone, D.·Hanson, A.·Nel, H.·Mesa, J. G.·El Kurdi, M.·Kenna, T.·Leo, P.·Rehaume, L.·Brown, M.·Ciccia, F.·Thomas, R.
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Abstract

ObjectiveDisturbances in immune regulation, intestinal microbial dysbiosis and intestinal inflammation characterize ankylosing spondylitis (AS), which is associated with RUNX3 loss-of-function variants. ZAP70W163C mutant (SKG) mice have reduced ZAP70 signaling, spondyloarthritis and ileitis. At intestinal epithelial interfaces, lamina propria Foxp3+ regulatory T cells (Treg) and intraepithelial CD4+CD8+TCR{beta}+ lymphocytes (CD4-IEL) control inflammation. TGF-{beta} and retinoic acid (RA)-producing dendritic cells are required for induction of Treg and for CD4-IEL differentiation from CD4+ conventional or Treg precursors, with upregulation of Runx3 and suppression of ThPOK. We investigated Treg, CD4-IEL, ZAP70 and Runx3 in SKG mice and AS patients. MethodsWe compared ileal Treg and CD4-IEL numbers and differentiation in BALB/c and SKG mice, and with ZAP70 inhibition, and related differentially-expressed genes in terminal ileum to ChIP-seq-identified Runx3-regulated genes. We compared proportions of CD4-IEL in ileum and CD4+8+ T cells in blood of AS patients and healthy controls. ResultsZAP70W163C or ZAP70 inhibition prevented intestinal CD4-IEL but not Foxp3+ Treg differentiation in context of TGF-{beta} and RA in vitro and in vivo, resulting in Runx3 and ThPOK dysregulation. CD4-IEL frequency and expression of tissue resident memory T-cell and Runx3-regulated genes was reduced in SKG intestine. Multiple under-expressed genes were shared with risk SNPs identified in human spondyloarthropathies. CD4-IEL were decreased in AS intestine. Double-positive T cells were reduced and Treg increased in AS peripheral blood. ConclusionHigh-affinity TCR-ZAP70 signalling is required for Runx3-mediated intestinal CD4-IEL differentiation from Treg. Genetically-encoded relative immunodeficiency of T cells underpins poor intestinal barrier control in mouse and human spondyloarthropathy. What is already known about this subject?Ankylosing spondylitis (AS) is associated with RUNX3 loss-of-function variants. Capacity of the AS T cell receptor repertoire to expand in response to infectious antigens is reduced. Foxp3+ regulatory T cells (Treg) are increased in AS intestine. ZAP70W163C mutant (SKG) mice have reduced ZAP70 signaling, spondyloarthritis (SpA) and ileitis. Intestinal epithelial Foxp3+ Treg and CD4+CD8+ cytotoxic lymphocytes (CD4-IEL) control local inflammation. CD4-IEL differentiate from Treg, with upregulation of Runx3 and suppression of ThPOK transcription factors. What does this study add?High-affinity TCR-ZAP70 signalling is required for Runx3-mediated intestinal CD4-IEL differentiation from Treg Intestinal CD4-IEL and circulating CD4+CD8+ T cells are reduced in AS while circulating Treg are increased. Impaired CD8 expression may be correctible by TNF inhibition in AS CD4+ T cells. Deficiencies of Runx3 and tissue-resident CD4-IEL link intestinal dysbiosis and inflammation in mouse and human SpA. How might this influence clinical practice or future developments?Genetically-encoded relative T immunodeficiency underpins poor intestinal barrier control in SpA

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Bhuyan, Z., Maradana, M., Rahman, M. A., Mehdi, A., Bergot, A.-S., Simone, D., Hanson, A., Nel, H., Mesa, J. G., El Kurdi, M., Kenna, T., Leo, P., Rehaume, L., Brown, M., Ciccia, F., Thomas, R.. 2022-07-30. Deficiencies of Runx3 and tissue-resident CD4+ intestinal epithelial lymphocytes link intestinal dysbiosis and inflammation in mouse and human spondyloarthropathy. https://doi.org/10.1101/2022.07.28.501834

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