IL ‐8 From Explant‐Cultured Human Visceral and Subcutaneous Adipose Tissue Upregulates CXCR2 Transcript Expression, Promoting CXCR2 ‐Dependent Insulin Resistance and Impaired Glucose Metabolism in Human HepG2 Hepatocytes

Type 2 diabetes mellitus has been demonstrated to be strongly associated with obesity, in which adipose tissue distribution plays a critical role. Different adipose tissue depots, particularly subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT), exert distinct effects on insulin resistance by influencing hepatocyte insulin signaling and glucose metabolism. Nevertheless, the molecular mechanisms underlying these depot-specific effects remain incompletely understood. Our preliminary findings revealed that VAT secretes markedly higher levels of interleukin-8 (IL-8) than SAT, suggesting that IL-8 may act as a key mediator linking adipose tissue heterogeneity to hepatic insulin sensitivity. A Transwell-based co-culture system was established to allow paracrine interaction between human HepG2 cells and adipose tissue derived from different anatomical depots. This study supports a major role for CXCR2-dependent signaling in hepatocyte insulin resistance and implicates VAT-derived IL-8 as a likely upstream mediator. Specifically, co-culture with adipose tissue resulted in a substantial impairment of insulin signaling, as evidenced by a decrease in the expression of IRS2, PI3K-p85, and phosphorylated Akt2 (Ser473), accompanied by an increase in the phosphorylation of IRS2 at Ser731. Silencing CXCR2 in HepG2 cells partially reversed these effects, restoring insulin signaling protein expression. Functional assays revealed that CXCR2 knockdown enhanced glucose uptake and glycogen storage, while CXCR2 overexpression significantly suppressed these processes. These alterations were more pronounced in the VAT co-culture group compared with the SAT group. In summary, the findings identify a critical role for CXCR2-dependent signaling linking adipose tissue secretomes-predominantly implicated with elevated VAT-derived IL-8-to the disruption of the IRS2/PI3K/Akt2 pathway in hepatocytes, supported by transcript-level regulation and functional genetic modulation.