Increased adipose tumor necrosis factor-α (TNF-α) expression in obesity. Adipose TNF-α gene expression was determined in six lean, 18 overweight, and 27 obese non-diabetic individuals using real-time RT-PCR, while TNF-α protein expression was also determined in five lean, 13 overweight, and 10 obese non-diabetic individuals using immunohistochemistry (IHC) as described in Materials and Methods. The data (mean ± SEM) show that (A) TNF-α adipose gene expression was higher in obese (P = 0.02) compared with lean individuals. (B) TNF-α protein expression (expressed as IHC intensity in arbitrary units) was also elevated both in overweight (P = 0.0009) and obese (P < 0.0001) compared with lean individuals. (C) The representative IHC images obtained from three independent determinations with similar results show increased adipose tissue TNF-α expression (blue arrows, 100× magnification) in overweight and obese individuals compared with lean. Scale bar = 50 μM. (D) IRF5 and TNF-α gene expression correlated positively in the adipose tissue (r = 0.50, P = 0.0004). The asterisks *, ***, and **** represent significance levels of P ≤ 0.05, P < 0.001, and P < 0.0001, respectively.