Decipher the molecular mechanism: The role of stromal vascular cells in mediating rat visceral adipose tissue dysfunction in alcohol-associated liver disease

Backgrounds: Alcohol-associated liver disease is one of the leading causes of chronic liver diseases in the United States. Chronic alcohol use induces adipocyte lipolysis and production of inflammatory mediators from adipose tissue (AT), which promotes hepatic steatosis and inflammation via the crosstalk between AT and liver. The mechanisms by which ethanol promotes inflammation and fibrosis in liver has been extensively studied. However, very little is known regarding the role of ethanol in causing AT inflammation and/or fibrosis, which, in turn, can impair the functions of AT. Stromal vascular cells (SVCs) are a heterogeneous group of AT cells and contribute to AT inflammation and remodeling in metabolic syndrome. However, their role in promoting AT dysfunction upon alcohol feeding remains unclear. The present study aims to test the hypothesis that SVCs contribute to the development of AT inflammation and fibrosis, thereby altering AT storage/secretory functions upon chronic ethanol exposure. Methods: Male wild-type Wistar rats (175 to 200 g) were fed 6.7% (v/v) ethanol-containing Lieber-DeCarli diet (ET) or an isocaloric control diet (CONT) for 6 weeks. Next, rats were euthanized, and visceral AT samples were collected. Hematoxylin and eosin staining and picrosirius red staining were performed to determine the effect of ethanol on adipocyte size and fibrosis in visceral AT. Primary rat SVCs were collected from visceral AT from CONT (n = 7) and ET rats (n = 7). Total RNAs were extracted from rat SVCs, and RNA sequencing analysis was performed to determine the molecular mechanism underlying the role of SVCs in mediating ethanol-induced rat visceral AT dysfunction. Real-time PCR and western blotting were carried out to validate transcriptomics results. Results: Chronic alcohol feeding decreased adipocyte size (P < 0.01) and increased collagen deposition (P < 0.05) in visceral AT of rats. RNA sequencing analysis identified 54 differentially expressed genes of primary rat SVCs in response to alcohol exposure (adjusted P < 0.05). Gene ontology enrichment analysis identified signaling pathways related to cellular response to interleukin 1 (IL1) and collagen-containing extracellular matrix that were significantly altered upon ethanol exposure in SVCs. Specifically, mRNA levels of genes related to these pathways, including purinergic receptor P2Y2 (P2ry2), a G-protein-coupled receptor regulating IL1b expression, and collagen type VIII alpha 1 chain (Col8a1) were increased (P < 0.05) in SVCs from rats fed an alcohol diet. Moreover, ethanol exposure increased the protein level of IL1b in the SVCs of rat visceral AT, indicating the effects of alcohol in promoting AT inflammation via activation of the P2RY2-IL1b axis. In addition, the ingenuity pathway analysis revealed that the transforming growth factor beta (TGFb) signaling was activated (z-score = 2.478, adjusted P < 0.0001) in SVCs of ethanol-fed rats. Therefore, chronic ethanol exposure leads to visceral AT fibrosis via the activation of TGFb and a resultant increase in Col8a1 expression. Conclusion: These findings suggest SVCs play a role in promoting visceral AT inflammation and fibrosis via activation of P2RY2-IL1b axis and TGFb-Col8a1 signaling pathway, respectively. Funding information: This study was supported by the NIH-NIAAA P50 award-Alcohol Center of Research-Nebraska (P50AA030407-5130). This abstract was presented at the American Physiology Summit 2026 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.