MicroRNA-34a dependent regulation of AXL controls the activation of dendritic cells in inflammatory arthritis.

Kurowska-Stolarska, Mariola; Alivernini, Stefano; Melchor, Emma Garcia; Elmesmari, Aziza; Tolusso, Barbara; Tange, Clare; Petricca, Luca; Gilchrist, Derek S et al. · Nat Commun · 2017

basic_science · Level V

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Abstract

Current treatments for rheumatoid arthritis (RA) do not reverse underlying aberrant immune function. A genetic predisposition to RA, such as HLA-DR4 positivity, indicates that dendritic cells (DC) are of crucial importance to pathogenesis by activating auto-reactive lymphocytes. Here we show that microRNA-34a provides homoeostatic control of CD1c<sup>+</sup> DC activation via regulation of tyrosine kinase receptor AXL, an important inhibitory DC auto-regulator. This pathway is aberrant in CD1c<sup>+</sup> DCs from patients with RA, with upregulation of miR-34a and lower levels of AXL compared to DC from healthy donors. Production of pro-inflammatory cytokines is reduced by ex vivo gene-silencing of miR-34a. miR-34a-deficient mice are resistant to collagen-induced arthritis and interaction of DCs and T cells from these mice are reduced and do not support the development of Th17 cells in vivo. Our findings therefore show that miR-34a is an epigenetic regulator of DC function that may contribute to RA.

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