Macrophage ß-arrestin-1 deteriorates DSS-induced colitis through interaction with NF-κB signaling.

ABSTRACT

ß-arrestin-1 has been demonstrated to participate in the regulation of inflammatory reactions in several diseases. Thus, this study aimed to investigate the role of macrophage ß-arrestin-1 in the pathogenesis and progression of ulcerative colitis (UC). A myeloid ß-arrestin-1 conditional knockout mouse model was generated to explore the role of macrophage ß-arrestin-1. DSS was employed for the establishment of an ulcerative colitis mouse model, using TNF-α as an inflammatory stressor in vitro. The expression level of ß-arrestin-1 was detected via western blot and immunofluorescence assays, whilst disease severity was evaluated by clinical score and H&E staining in the DSS-induced colitis model. In the in vitro experiments, the levels of inflammatory cytokines were examined using real-time PCR. NF-κB activation was detected through the double luciferase reporter system, western blot, and electrophoretic mobility shift assay (EMSA). BAY11-7082 was used to inhibit NF-κB activation. Our results exposed that the level of ß-arrestin-1 was increased in monocytes/macrophages derived from DSS-induced colitis mice or under the TNF-α challenge. Moreover, conditionally knocking out the expression of myeloid ß-arrestin-1 alleviated disease severity, while knocking out the expression of ß-arrestin-1 decreased the levels of inflammatory cytokines. Additionally, NF-κB was identified as a central regulatory element of ß-arrestin-1 promoter, and using BAY11-7082 to inhibit NF-κB activation lowered the level of ß-arrestin-1 under TNF-α challenge. ß-arrestin-1 led to the activation of the NF-κB signaling pathway by enhancing binding to IκBα and IKK under the TNF-α challenge. Taken together, our findings demonstrated macrophage ß-arrestin-1 contributes to the deterioration of DSS-induced colitis through the interaction with NF-κB signaling, thus highlighting a novel target for the treatment of UC.