Escherichia coli Nissle 1917 Modulates the RNF150/ELAVL1 Ubiquitination Pathway to Ameliorate Obesity-driven Insulin Resistance in High-fat Diet-fed Mice.

BACKGROUND & AIMS: Obesity, a global epidemic, fuels metabolic dysfunction through complex gut microbiota‒immune system crosstalk. The probiotic Escherichia coli Nissle 1917 (EcN) holds promise for alleviating obesity-related complications, yet its mechanistic underpinnings remain unclear. This study explored the therapeutic potential of EcN, focusing on its ability to regulate the ring finger protein 150 (RNF150)/embryonic lethal abnormal vision-like 1 (ELAVL1) axis in macrophages to counter high-fat diet (HFD)-induced obesity and insulin resistance. METHODS: We employed a 12-week dietary intervention in male C57BL/6J mice and administered EcN. Fecal microbiota transplantation (FMT) and myeloid-specific RNF150 and ELAVL1 knockout models were used to establish mechanistic causality. The gut microbiota composition was analyzed via 16S rRNA sequencing, whereas metabolic parameters, adipose tissue inflammation, and RNF150/ELAVL1 interactions were assessed via glucose/insulin tolerance tests, immunohistochemistry, Western blotting, coimmunoprecipitation, and ubiquitination assays. RNF150 expression was also evaluated in adipose tissue and peripheral blood mononuclear cells from overweight and normal-weight human subjects. RESULTS: EcN treatment significantly reduced HFD-induced weight gain, adipose accumulation, and insulin resistance while restoring the gut microbiota balance (decreased the Firmicutes/Bacteroidetes ratio and increased Muribaculaceae). FMT from EcN-treated mice recapitulated these benefits. EcN attenuated inflammation across the liver, adipose, and colon, reducing proinflammatory cytokine levels and macrophage infiltration. RNF150 was upregulated in HFD-fed mice and human overweight samples but downregulated by EcN. Myeloid RNF150 deletion mirrored the effects of EcN, promoting anti-inflammatory M2 macrophages and insulin sensitivity. RNF150 mediated ELAVL1 ubiquitination and degradation, whereas ELAVL1 stabilization enhanced anti-inflammatory responses. Myeloid ELAVL1 deletion worsened metabolic outcomes. CONCLUSIONS: EcN ameliorates obesity and insulin resistance by modulating the gut-adipose axis via RNF150/ELAVL1 in macrophages, suggesting novel therapeutic targets for metabolic disorders.