Edited Filamin A in myeloid cells reduces intestinal inflammation and protects from colitis

Patho-mechanistic origins and disease dynamics of ulcerative colitis are still poorly understood. The actin-crosslinker Filamin A (FLNA) impacts cellular responses through interaction with cytosolic proteins. FLNA exists in two forms that differ only in one amino acid: genome-encoded FLNAQ and FLNAR - generated by post-transcriptional A-to-I editing. FLNA is edited in fibroblasts, smooth muscle- and endothelial cells in the colon. We identified the FLNA editing status as a key determinant of colitis severity. FLNA editing was highest in healthy colons and reduced during acute murine and human colitis. Mice that exclusively express edited FLNAR and do not downregulate editing upon challenge were highly resistant to DSS-induced colitis, whereas fully unedited FLNAQ animals developed severe inflammation. While the genetic induction of FLNA editing influenced transcriptional states of structural cells and the microbiome composition, we found that FLNAR exerts protection specifically via its influence on myeloid cells, which are not edited under physiological conditions. Introducing fixed, fully edited FLNAR did not hamper normal cell migration but reduced macrophage inflammation and rendered neutrophils less prone to NETosis. In conclusion, loss of FLNA editing correlates with colitis severity, and targeted FLNA editing of myeloid cells might serve as a novel therapeutic approach in intestinal inflammation. SummaryIn this study, Gawish et al. show that RNA editing of the actin cross-linker FLNA is similarly regulated in mice and humans and that the targeted induction of edited FLNAR in myeloid cells governs resistance to DSS-induced colitis, revealing its potential in IBD therapy.