Upregulated adipose tissue chemokine CXC motif ligand-8 (CXCL8) expression in obesity. Adipose CXCL8 gene expression was determined in five lean, 18 overweight, and 27 obese non-diabetic individuals using real-time RT-PCR, while CXCL8 protein expression was determined in six lean, 14 overweight, and 10 obese non-diabetic individuals using immunohistochemistry (IHC) as described in Materials and Methods. The data (mean ± SEM) show that (A) adipose CXCL8 gene expression was upregulated in obese (P = 0.05) compared with lean individuals. (B) CXCL8 protein expression (IHC intensity in arbitrary units) was also higher in obese (P = 0.0001) compared with lean individuals. (C) The representative IHC images obtained from three independent determinations with similar results show upregulated adipose CXCL8 expression (purple arrows, 100× magnification) in overweight and obese as compared with lean individuals. Scale bar = 50 μM. (D) IRF5 and CXCL8 gene expression was associated with each other in the adipose tissue (r = 0.40, P = 0.0004). The asterisks * and *** represent significance levels of P ≤ 0.05 and P < 0.001, respectively.