Endothelin-1 increases IL-6 production by vascular smooth muscle cells via canonical NFkB pathway

Obesity causes an increase in pro inflammatory immune cells in visceral adipose. Our lab reported that blockade of endothelin-1 type A (ETA) receptors attenuates adipose tissue inflammation in mice fed a high fat diet for 10 weeks. Literature suggests that ET-1 exerts its proinflammatory effect by activating ETA receptors on VSMCs via nuclear factor kappa b (NFkB) mediated increase in interleukin 6 (IL-6). We recently reported that vascular smooth muscle cell (VSMC) specific knockout of ETA receptors attenuates obesity induced inflammatory immune cell infiltration in white adipose; however, the mechanisms are not fully understood. We hypothesized that ET-1 causes inflammation by activating ETA on VSMCs leading to increased IL-6 production via canonical NFkB pathway. To test this hypothesis, we treated VSMC with ET-1 or vehicle for 24 hours in the presence or absence of inhibitors that target various parts of the NFkB pathway. When treated with endothelin-1, the mRNA expression of the proinflammatory cytokine IL-6 increased 4-fold (p<0.05, but there was no detectable difference in the expression of other cytokines including IL-1b, TGFb, or IFNg cytokines. Next, we found that IL-6 protein release increased 2-fold when treated with ET-1; however, the increase in IL-6 was abolished when cells were pretreated with the ETA antagonist BQ-123, but pretreatment with BQ-788 had no detectable effect on ET-1 induced IL-6 production in VSMCs. Finally, we found that co-treatment with an IKK-β inhibitor, which inhibits the canonical NFkB pathway abolished the increase in IL-6 production in response to ET-1. This attenuation was not observed with an IKK- ε inhibitor and surprisingly, IL-6 production was significantly increased in both control and ET-1 treated cells in the presence of an IKK - ε /TBK1 inhibitor. These data indicate that ET-1 may cause inflammation by activating the canonical NFkB pathway to increase IL-6 production by VSMCs. National Institute of Diabetes, Digestive, and Kidney Diseases, 5R01DK124327 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.