Next, the tissue distribution of MIC A/B was examined by immunohistochemistry. The diffuse cellular staining pattern of MIC A/B in patients with NASH in Fig. 1C is no artifact but rather typical of this kind of stain.27 In contrast, control hepatocytes were negative while individuals with NAFL weakly expressed MIC A/B. Hepatic NK cells play a critical
role in TRAIL- and Fas-mediated liver injury. The liver harbors many NK cells,28 and approximately 30% to 40% of these constitutively express TRAIL.29 We thus questioned whether the expression of TRAIL–DR5 and CD95/Fas mRNAs is increased BAY 57-1293 in NASH livers. Indeed, a 2.7-fold increase in TRAIL–DR5 and a 3.6-fold increase in CD95/Fas mRNA were observed in patients with NASH compared with controls (Fig. 2A). TRAIL–DR5 mRNA was significantly less increased in individuals with NAFL STI571 concentration compared with patients with NASH (1.1 ± 0.1 versus 2.7 ± 0.2, P = 0.01). In contrast,
CD95/Fas transcripts were also reduced in the NAFL group, but this difference was not significant when compared with patients with NASH (2.5 ± 0.5 versus 3.6 ± 0.9; P = 0.16). Up-regulation of CD95/Fas in patients with NASH was further confirmed through ELISA and demonstrated a significant increase as compared with both healthy controls and individuals with NAFL (P < 0.05). However, up-regulation of CD95/Fas was not accompanied by enhancement of medchemexpress the Fas ligand (Fig. 2B). Subsequently, histopathological examination was performed along with determination of serum alanine aminotransferase and aspartate aminotransferase values. The NAS is a well-established scoring system for patients with NASH as a progressive form of NAFLD.17 As expected, histopathological examinations from patients with NASH displayed an increase in NAS as compared with
controls. In addition, a marked elevation in serum alanine aminotransferase and aspartate aminotransferase values was also observed in patients with NASH versus controls (Fig. 2C). Liver enzymes from individuals with NAFL were within the reference ranges. In order to examine potential effects of MIC A/B on hepatocyte death rates in NASH, we quantified the intrahepatic rates of apoptotic (by M30 and confirmatory TUNEL assays) and overall cell death (by M65 assay). As expected, M30 expression was significantly elevated in patients with NASH (440.5 ± 71.1 U/L) as compared with controls (94.4 ± 30.9 U/L; P < 0.05) (Fig. 3A), which went along with a likewise significantly increased M65 expression in patients with NASH versus controls (784.9 ± 129.9 U/L versus 230.3 ± 43.5 U/L; P < 0.05). In contrast, M30 levels were significantly reduced in individuals with NAFL (139.5 ± 20.9 U/L), which was again reflected in the significantly lower M65 expression in NAFL (298.2 ± 35.4 U/L).