Nonalcoholic Steatohepatitis Injury Research Articles

Study of Cytochrome P450 2E1 and its allele Variants in Liver Injury of Nondiabetic, Nonalcoholic Steatohepatitis Obese Women

CYP2E1 enzyme is related to nonalcoholic steatohepatitis (NASH) due to its ability for reactive oxygen species production, which can be influenced by polymorphisms in the gene. The aim of this study was to investigate hepatic levels, activity, and polymorphisms of the CYP2E1 gene to correlate it with clinical and histological features in 48 female obese NASH patients. Subjects were divided into three groups: (i) normal; (ii) steatosis; and (iii) steatohepatitis. CYP2E1 protein level was assayed in microsomes from liver biopsies, and in vivo chlorzoxazone hydroxylation was determined by HPLC. Genomic DNA was isolated for genotype analysis through PCR. The results showed that liver CYP2E1 content was significantly higher in the steatohepatitis (45%; p=0.024) and steatosis (22%; p=0.032) group compared with normal group. Chlorzoxazone hydroxylase activity showed significant enhancement in the steatohepatitis group (15%, p=0.027) compared with the normal group. c2 rare allele of RsallPstl polymorphisms but no C allele of Dral polymorphism was positively associated with CHZ hydroxylation, which in turn is correlated with liver CYP2E1 content (r=0.59; p=0.026). In conclusion, c2 allele is positively associated with liver injury in NASH. This allele may determine a higher transcriptional activity of the gene, with consequent enhancement in pro-oxidant activity of CYP2E1 thus affording liver toxicity.

Progressive Fibrosis in Nonalcoholic Steatohepatitis: Association With Altered Regeneration and a Ductular Reaction

Portal fibrosis and linkage is a key feature of progressive disease in nonalcoholic steatohepatitis (NASH), but not simple steatosis. It is underappreciated and poorly understood. Fatty liver has impaired regeneration that induces a secondary replicative pathway using bipotential, periportal, hepatic progenitor cells (HPCs). We propose that activation of this pathway, with increased cell injury in NASH, also induces a periportal ductular reaction (DR) that could produce a profibrogenic stimulus. Biopsy specimens from 107 patients with nonalcoholic fatty liver disease and 11 controls were immunostained with cytokeratin-7 to quantify the DR and HPCs, and with p21 to assess hepatocyte replicative arrest. These results were correlated with clinicopathologic variables. Patients with nonalcoholic fatty liver disease had expansion of HPCs, with a strong association between HPCs and the DR (r(s) = 0.582, P < .0001). In those with NASH (n = 69) there was an increased DR compared with simple steatosis, which correlated with the stage of fibrosis (r(s) = 0.510, P < .0001). The DR increased with the grade of NASH activity (r(s) = 0.478, P < .0001), grade of portal inflammation (r(s) = 0.445, P < .0001), and extent of hepatocyte replicative arrest (r(s) = 0.446, P < .0001). Replicative arrest was in turn associated with insulin resistance (r(s) = 0.450, P < .0001) and NASH activity (r(s) = 0.452, P < .0001). By multivariate analysis, the extent of DR (odds ratio [OR] = 17.9, P = .016), hepatocyte ballooning (OR = 8.1, P < .0001), and portal inflammation (OR = 3.3, P = .005) were associated independently with fibrosis. These findings suggest that an altered replication pathway in active NASH promotes a periportal DR, which in turn may provoke progressive periportal fibrogenesis.

Treatment of fibrosis in nonalcoholic fatty liver disease

Nonalcoholic steatohepatitis (NASH) is one of the most common liver disorders in North America. The mechanism of liver injury in NASH involves insulin resistance and oxidative stress as well as cytokine release. Therapeutic interventions aimed at enhancing insulin sensitivity or reducing oxidative stress have been studied. The role of peptide hormones secreted by adipose tissue--adipocytokines--in the potential pathogenesis of NASH is an area of intense research. As the function of adipokines in modulating hepatic inflammation and fibrosis is elucidated, the potential for novel treatment strategies in patients with NASH is likely to be realized.

Fatty liver and the metabolic syndrome

Nonalcoholic fatty liver disease and its subset nonalcoholic steatohepatitis represent the liver manifestations of insulin resistance. This review briefly summarizes advances in our understanding of the pathogenesis of nonalcoholic fatty liver disease and its prevalence, natural history and treatment. The recognition of the role the renin-angiotensin system in promoting insulin resistance is worth noting because of available drugs. Endoplasmic reticulum stress has also become a recent target of investigation because endoplasmic reticulum stress is common in obesity, diabetes and various forms of liver disease including nonalcoholic fatty liver disease. Endoplasmic reticulum stress may be responsible for activation of c-Jun kinase, a process that may cause the hepatocellular injury in nonalcoholic steatohepatitis. Progress has also been made in estimating the prevalence of nonalcoholic fatty liver disease in adults and children. Patients enrolled in the Dallas Heart Study were found to have a 33% prevalence of nonalcoholic fatty liver disease and children dying of accidental deaths in San Diego were found to have a 13% prevalence of nonalcoholic fatty liver disease. Because about 10% of people with nonalcoholic fatty liver disease are at risk for progressive fibrosis, the burden of this disease is now quite substantial. Incremental progress in understanding nonalcoholic fatty liver disease and nonalcoholic steatohepatitis promises to lead to new therapeutic options for this common disease.

Apoptosis and Bcl-2 expression in the livers of patients with steatohepatitis

Apoptosis may play a role in the pathogenesis of alcoholic (ASH) and non-alcoholic steatohepatitis (NASH). In this study, we investigated the modulation of apoptosis-related liver proteins in steatohepatitis. Hepatocyte apoptosis was evaluated by the TUNEL assay in liver tissue of 12 patients with NASH, 12 with ASH and in histologically normal controls. In addition, caspase-3 processing was evaluated by immunoblot analysis. Expression of death receptors, Bcl-2 family members, and NF-kappaB inhibitor (IkappaB) were determined by western blot. Liver biopsies were also graded for inflammation and fibrosis. Apoptotic hepatocytes were markedly increased in NASH (P<0.05) and ASH (P<0.001) as compared to controls. Active caspase-3 was also elevated in steatohepatitis (P<0.01), coinciding with upregulation of pro-apoptotic Bax (P<0.001). Further, production of tumour necrosis factor-receptor 1 was increased up to 4-fold (P<0.05). Degradation of IkappaB increased >70% in steatohepatitis (P<0.001). Notably, Bcl-2 was also strongly expressed (>100-fold; P<0.001). These data were significantly correlated with relative degrees of portal and lobular inflammation. The results show that liver injury in NASH and ASH is associated with apoptosis and NF-kappaB activation. Anti-apoptotic Bcl-2 is strongly expressed, probably reflecting an adaptive response to obesity or alcohol-related stress.

Obstructive sleep apnea: wreaking havoc with homeostasis

the phenotypic characterization of obstructive sleep apnea (OSA) continues to unfold. Recent studies provide evidence that this syndrome has the potential to disturb cardiovascular, neurological, and endocrine homeostatic processes ([1][1], [6][2], [8][3], [9][4]). Li et al. ([5][5]) present

Steatosis in chronic hepatitis C: Relative contributions of obesity, diabetes mellitus, and alcohol

Steatosis has emerged as a histologic finding of importance to the progression of hepatitis C virus (HCV)-associated liver disease. However, most studies of HCV-associated steatosis have excluded alcohol drinkers and individuals with diabetes and thus have not addressed the relative contribution of known causes of steatosis to liver injury in HCV-associated disease. To address this issue, we studied 297 consecutive patients with HCV who met inclusion criteria. Alcohol consumption, demographics, and serologic tests were correlated with degrees of steatosis and fibrosis on liver biopsy. Liver biopsy specimens were also examined for evidence of significant alcohol or nonalcoholic steatohepatitis (NASH) injury. In univariate analysis, steatosis correlated with type 2 diabetes mellitus ( P = .005) and body mass index (BMI) ( P = .0001) but not with the intensity of alcohol intake (in grams per day). In multivariate analysis, BMI ( P = .0002) and genotype 3a infection ( P = .02) were independent predictors of steatosis. When patients with risk factors for NASH were excluded, genotype 3a infection was the only independent predictor of steatosis. Steatosis ( P = .04) and inflammation ( P < .0001) scores on liver biopsy were the only independent predictors of fibrosis. Significant alcohol or NASH injury was found in only 6% of biopsy specimens. In conclusion, steatosis in HCV infection is associated with risk factors for NASH, particularly obesity, rather than alcohol consumption. (H EPATOLOGY 2002;36:729-736.)

Ubiquitin as a Marker of Cell Injury in Nonalcoholic Steatohepatitis

Ubiquitin (UB), an intracellular protein that binds to other proteins to target them for proteolysis, is associated with Mallory hyalin (MH), which supports a biopsy diagnosis of nonalcoholic steatohepatitis (NASH). We analyzed 54 liver biopsy specimens from 49 patients with a clinical diagnosis of NASH for immunoreactive UB and multiple features of necroinflammation, fibrosis, and Prussian blue-positive iron to determine whether the presence of immunoreactive UB increases detection of MH or correlates with other features of cell injury or mutations of the HFE gene. MH and UB were graded. Analysis for HFE gene mutations was performed in 48 patients. Biopsy diagnoses were distributed as follows: NASH, 42; steatosis, 10; and nonspecific changes, 2. UB was present in 20 specimens and MH in 23. Of 31 specimens with 0 MH, 6 had UB; of 14 with 1 + (questionable) MH, 7 had 1+ or 2+ UB. UB correlated positively and significantly with the diagnosis and grade of NASH, presence of MH, cell swelling, lobular inflammation, and fibrosis. Immunostaining for UB may enhance detection of MH in questionable cases, support the diagnosis of NASH, and indicate which patients may be at risk for progression of disease.