Mitochondrial dysfunction might play a central role in the pathogenesis of nonalcoholic steatohepatitis (NASH). The aims of this study were to evaluate whether free fatty acid (FFA) transport into the mitochondria or the activity of mitochondria respiratory chain (MRC) complexes are impaired in NASH. In patients with NASH and control subjects, we measured free carnitine, short-chain acylcarnitine (SCAC) and long-chain acylcarnitine (LCAC) esters, carnitine palmitoyltransferase (CPT) activity, and MRC enzyme activity in liver tissue as well as serum concentration of tumor necrosis factor a (TNF-a), homeostatic metabolic assessment of insulin resistance (HOMAIR), and body mass index (BMI). In patients with NASH, the LCAC/free carnitine ratio was significantly increased and the SCACIfree carnitine ratio was decreased. In patients with NASH, the activity of the MRC complexes was decreased to 63% f 20% (complex I), 58.5% f 16.7% (complex 11), 70.6% 2 10.3% (complex TII), 62.5% f 13% (complex IV), and 42.4% f 9.1% (adenosine triphosphate synthase) of the corresponding control values. Activity of these complexes correlated significantly with serum TNF-a and HOMAIR. Serum TNF-a (36.3 f 23.1 pg/mL), HOMAIR (4.5 f 2.38), and BMI (29.9 2 3.5 kg/m2) values were significantly increased in patients with NASH. In conclusion, activities of MRC complexes were decreased in liver tissue of patients with NASH. This dysfunction correlated with serum TNF-a, insulin resistance, and BMI values. (HEPATOLOGY 2003;38:999-1007.) N onalcoholic steatohepatitis (NASH) is a clinicopathologic condition characterized by histologic features of alcoholic liver disease that occurs in patients who do not consume significant amounts of alcohol.' At this moment, NASH is considered part of a large spectrum of nonalcoholic fatty liver disease that also includes pure fatty liver (hepatic steatosis), hepatic steato-

The mechanisms responsible for low mitochondrial respiratory chain (MRC) activity in the liver of patients with nonalcoholic steatohepatitis are unknown. In this study, we examined the cause of this dysfunction in ob/ob mice.

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Fibrosis results from an increase in the synthesis and deposition of type I collagen. Fibrosis is frequently associated with inflammation, which is accompanied by increased levels of tumor necrosis factor-alpha (TNFalpha) and activation of the transcription factor NF-kappaB. However, several agents known to activate NF-kappaB, such as phorbol 12-myristate 13-acetate (PMA) and TNFalpha, result in decreased expression of type I collagen. Therefore, we directly examined the effects of NF-kappaB on alpha1(I) collagen gene expression in two collagen-producing cells, NIH 3T3 fibroblasts and hepatic stellate cells (HSCs). Transient transfections of NIH 3T3 cells or HSCs using NF-kappaB p50, p65, and c-Rel expression plasmids with collagen reporter gene plasmids demonstrated a strong inhibitory effect on transcription of the collagen gene promoter. Dose-response curves showed that p65 was a stronger inhibitor of collagen gene expression than was NF-kappaB p50 or c-Rel (maximum inhibition 90%). Transient transfections with reporter gene plasmids containing one or two Spl binding sites demonstrated similar inhibitory effects of NF-kappaB p65 on the activity of these reporter genes, suggesting that the inhibitory effects of NF-kappaB p65 are mediated through the critical Spl binding sites in the alpha1(I) collagen gene promoter. Cotransfection experiments using either a super-repressor I[ke]B or Spl partially blocked the inhibitory effects of p65 on collagen reporter gene activity. Coimmunoprecipitation experiments demonstrated that NF-kappaB and Spl do interact in vivo. Nuclear run-on assays showed that NF-kappaB p65 inhibited transcription of the endogenous alpha1(I) collagen gene. Together, these results demonstrate that NF-kappaB decreases transcription of the alpha1(I) collagen gene.