TRIM58 Restrains Intestinal Mucosal Inflammation by Negatively Regulating TLR2 in Myeloid Cells.

Balanced control of innate immune signaling in the intestine represents an important host defense mechanism to avoid inappropriate responses that may exacerbate mucosal injury in acute inflammation. In this study, we report that TRIM58, a RING E3-ubiquitin ligase, associates with TLR2. The interaction was found in a yeast two-hybrid screen (human leukocyte and mononuclear library) and confirmed by coimmunoprecipitation of tagged and endogenous proteins. TRIM58 was predominantly expressed by murine and human myeloid-derived cells. Stimulation with a TLR2 ligand modulated TRIM58 synthesis in myeloid cells. Overexpression of TRIM58, but only in presence of the RING domain, promoted proteasome-dependent degradation of TLR2, inhibiting its signaling activity. Genetic deletion of Trim58 in mice (Trim58 -/-) led to impaired resolution of acute dextran sodium sulfate-induced colitis, which was characterized by delayed recovery from colonic injury and associated with enhanced expression of TLR2 protein and proinflammatory cyto/chemokine production in inflamed colons. Using myeloid cell-specific deletion of Trim58 in mice, we demonstrated that the myeloid cell compartment was responsible for early colitis acceleration in Trim58 deficiency. In vitro studies revealed that Trim58 -/- myeloid cells, which showed constitutive upregulation of TLR2 protein, overreacted to a proinflammatory milieu (TNF-α and IFN-γ) with increased IL-1β protein production, which mechanistically depended on Tlr2 Finally, we found that TRIM58 mRNA and protein expression levels were reduced in colonic specimens from patients with ulcerative colitis. In conclusion, we identify TRIM58 as a novel negative mediator of innate immune control and mucosal homeostasis via TLR2 signaling. Dysfunction of TRIM58 in myeloid cells may contribute to ulcerative colitis pathogenesis.