The proliferation of hepatic stellate cells (HSCs) is a critical step in hepatic fibrogenesis. Platelet‐derived growth factor (PDGF) is the most potent mitogen for HSCs. We investigated the role of nonphagocytic NAD(P)H oxidase–derived reactive oxygen species (ROS) in PDGF‐induced HSC proliferation. The human HSC line, LI‐90 cells, murine primary‐cultured HSCs, and PDGF‐BB were used in this study. We examined the mechanism of PDGF‐BB‐induced HSC proliferation in relation to the role of a ROS scavenger and diphenylene iodonium, an inhibitor of NAD(P)H oxidase. We also measured ROS production with the aid of chemiluminescence. We showed that PDGF‐BB induced proliferation of HSCs through the intracellular production of ROS. We also demonstrated that HSCs expressed key components of nonphagocytic NAD(P)H oxidase (p22phox, gp91phox, p47phox, and p67phox) at both the messenger RNA and protein levels. Diphenylene iodonium suppressed PDGF‐BB–induced ROS production and HSC proliferation. Coincubation of H2O2 and PDGF‐BB restored the proliferation of HSCs that was inhibited by diphenylene iodonium pretreatment. Phosphorylation of the mitogen‐activated protein kinase (MAPK) family constitutes a signal transduction pathway of cell proliferation. Our data demonstrate that NAD(P)H oxidase–derived ROS induce HSC proliferation mainly through the phosphorylation of p38 MAPK. Moreover, an in vivo hepatic fibrosis model also supported the critical role of NAD(P)H oxidase in the activation and proliferation of HSCs. In conclusion, NAD(P)H oxidase is expressed in HSCs and produces ROS via activation of NAD(P)H oxidase in response to PDGF‐BB. ROS further induce HSC proliferation through the phosphorylation of p38 MAPK. (HEPATOLOGY 2005;41:1272–1281.)

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The natural course of hepatitis C virus (HCV) infection has not been fully elucidated. To investigate whether HCV is spontaneously eliminated in chronic carriers, a long-term population-based cohort study was conducted on 435 chronic HCV carriers. Individual characteristics, serum HCV RNA, and liver function tests were analyzed, and ultra sonography (US) was performed in all subjects. Subjects were followed up for 7.2 +/- 2.4 years (mean +/- SD). Serum HCV RNA was spontaneously eliminated in 16/435 (3.7%) individuals during this period; thus, the incidence of spontaneous elimination of serum HCV RNA was 0.5%/year/person. Multivariate analysis revealed that both a low value of ZTT and no US finding of chronic liver disease were associated with spontaneous viral elimination in HCV carriers. Three of these 16 individuals had chronic hepatitis, and 13 of them had normal ALT levels. When the neutralization of binding (NOB) assay that evaluates inhibition of the HCV envelope-2 protein binding to human cells was examined using sera from these 16 individuals, the NOB antibody was detected in only 3 cases with chronic hepatitis. These results suggest that serum HCV RNA is spontaneously eliminated in chronic HCV carriers in a population, and that the development of NOB antibody is associated with a natural resolution of chronic hepatitis in the minority of them.

No abstract

The asialoglycoprotein receptor (ASGPR) is abundantly expressed on the sinusoidal surfaces of hepatocytes. We aimed to clarify the clinical significance of the regional distribution of ASGPRs in the human liver, especially in chronic viral hepatitis. Eighteen volunteers, 34 patients with chronic hepatitis, and 33 patients with cirrhosis (11/Child-Pugh A, 11/Child-Pugh B, 11/Child-Pugh C) were studied using a newly developed, conventional technetium-99m-diethylenetriaminepentaacetic acid-galactosyl human serum albumin ((99m)Tc-GSA), single photon emission computed tomography (SPECT) method. Using Cantlie's line as a guide, ASGPR dynamics were analyzed separately in the right and left lobes, as well as in the whole liver, using novel indices (the liver uptake ratio [LUR] and the liver uptake density [LUD], which reflect the amount and density of ASGPRs in the liver, respectively). Mean LUR and LUD values for the whole liver and the right and left lobes decreased with increasing progression of chronic viral hepatitis. The LUR for the whole liver correlated well with parameters measuring the hepatic functional reserve and the platelet count. The right LUR correlated particularly well with conventional liver function tests, and comparison of the right LUD with histologic findings showed that it was a good indicator of periportal and/or bridging necrosis and fibrosis. In conclusion, our (99m)Tc-GSA SPECT method was clinically useful in evaluating regional hepatic function and the progression of chronic viral hepatitis using dynamic changes in ASGPRs.