Inhibition of the expression of proinflammatory mediators that are regulated by the NF-kappaB and STAT signaling pathways contribute to the therapeutical effect of glutamine in the TNBS model of experimental colitis. These effects may be brought about by inhibition of oxidative stress and reduced expression of proinflammatory cytokines.
Objectives: To evaluate whether reduced activity of the anti-inflammatory HSP70 pathway correlates with nonalcoholic fatty liver disease (NAFLD) progression and with markers of oxidative stress because obesity activates inflammatory JNKs, whereas HSP70 exerts the opposite effect. Methods: Adult obese patients (N 5 95) undergoing bariatric surgery were divided into steatosis (ST), steatohepatitis (SH), and fibrosis (SH1F) groups. The levels of HSP70, its major transcription factor, HSF1, and JNKs were assessed by immunoblotting hepatic and visceral adipose tissue; data were confirmed by immunohistochemistry. Plasma biochemistry (lipids, HbA 1c , HOMA, hepatic enzymes, and redox markers) was also evaluated. Results: In both liver and adipose tissue, decreased HSP70 levels, paralleled by similar reductions in HSF1 and reduced plasma antioxidant enzyme activities, correlated with insulin resistance and with NAFLD progression (expression levels were as follows: ST > SH > SH 1 F). The immunohistochemistry results suggested Kupffer cells as a site of HSP70 inhibition. Conversely, JNK1 content and phosphorylation increased. Conclusions: Decreased HSF1 levels in the liver and fat of obese patients correlated with impairment of HSP70 in an NAFLD stage-dependent manner. This impairment may affect HSP70-dependent anti-inflammation, with consequent oxidative stress and insulin resistance in advanced stages of NAFLD. Possible causal effects of fat cell senescence are discussed.
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