Conformational anti‐cytochrome P4502E1 (CYP2E1) auto‐antibodies contribute to necro‐inflammatory injury in chronic hepatitis C

Summary. Circulating auto‐antibodies against cytochrome P4502E1 (CYP2E1) have been observed in a significant fraction of patients with chronic hepatitis C (CHC). This study investigated the clinical significance of these auto‐antibodies in relation to their antigen specificity. The presence of anti‐CYP2E1 IgG was investigated in 137 consecutive patients with biopsy‐proven CHC. Anti‐CYP2E1 IgG above control threshold levels was detected in 52 (38%) subjects. By combined immunoprecipitation and western blotting, we observed that among anti‐CYP2E1 IgG‐positive sera, 23 (44%) were unreactive towards denaturated CYP2E1, indicating a prevalent recognition of conformational CYP2E1 antigens. Conformational anti‐CYP2E1 auto‐antibodies were unrelated to circulating gamma‐globulins, alcohol intake or infection by specific HCV genotypes. The presence of anti‐CYP2E1 auto‐antibodies was associated with an 11‐fold (OR 10.9 95%CI 1.4–86.6 P = 0.008) increased prevalence of necro‐inflammatory grading ≥4 (Ishack’s criteria) and 4‐fold (OR 4.0; 95%CI 1.3‐11‐7: P = 0.014) increased prevalence of fibrosis staging ≥2, respectively. Multivariate analysis confirmed conformational anti‐CYP2E1 IgG (P = 0.005) and age (P = 0.033) as independent predictors of necro‐inflammatory grading ≥4. The development of anti‐CYP2E1 auto‐antibodies targeting conformational CYP2E1 epitopes is associated with more severe liver damage in CHC.     

Early down‐regulation of cytochrome P450 3A and 2E1 in the regenerating rat liver is not related to the loss of liver mass or the process of cellular proliferation

Abstract: Aims/Background: Conflicting data have been reported concerning the modification of cytochrome P450 expression in the regenerating liver. Ligation of branches of the portal vein (PBL) perfusing 70% of the liver parenchyma, which produces regeneration and atrophy within the same liver, constitutes an ideal model to study the relative specificity of the early events in the regenerating liver and their relationship to the loss of liver mass. Methods: In this PBL model and in sham models, we studied the expression and the metabolic activities of two major cytochromes, CYP3A and CYP2E1, and the expression of inducible nitric oxide synthase protein (iNOS). They were simultaneously measured in the atrophying and regenerating liver lobes following PBL using Western Blot and HPLC methods. Results: The metabolic activities of both cytochromes were transiently and simultaneously down‐regulated in the regenerating and atrophying lobes during the first 2–5 h after PBL. No significant modification was observed at the protein level. In contrast, iNOS protein was significantly induced in both lobes. Similar results were observed after sham operation. Conclusions: The reduction of these CYP activities in both lobes after PBL and in sham livers suggests that other mechanisms than the regenerating process itself or the reduction of the liver mass might account for such down‐regulation during the early phase of liver regeneration. The activation of nitric oxide (NO) and/or pro‐inflammatory cytokine production provides clues to pathways liable to affect the CYP activities in the regenerating liver.     

Effects of 1‐O‐hexyl‐2,3,5‐trimethylhydroquinone on carbon tetrachloride‐induced hepatic cirrhosis in rats

Aim: The present study was undertaken to evaluate the effects of 1‐O‐hexyl‐2,3,5‐trimethylhydroquinone (HTHQ), a synthesized vitamin E derivative, on carbon tetrachloride (CCl₄)‐induced cirrhosis. Methods: Rats were treated with hypodermic injections of CCl₄ twice a week to induce the hepatic cirrhosis, and given drinking water containing HTHQ or solvent. Primary cultures of rat hepatocytes were performed to evaluate the effects of HTHQ on the expression of inducible nitric oxide synthase (iNOS). Results: Masson's staining of rat livers showed fibrosis around pseudo‐lobules in the CCl₄ group, the lesions being reduced in the CCl₄ HTHQ group. Increases in liver tissue hydroxyproline and α₁(I) collagen, α‐smooth muscle actin and iNOS induced by CCl₄, were also markedly diminished by HTHQ. Furthermore, both HTHQ and vitamin E attenuated interleukin‐1β‐induced iNOS protein expression in cultured hepatocytes, the potency of HTHQ being 10‐times higher than that of vitamin E. Conclusion: HTHQ may inhibit development of hepatic cirrhosis in rats, more potently than vitamin E, by inhibiting the iNOS expression in hepatocytes. Because vitamin E has a radical scavenging action, roles of NO and peroxynitrite will be discussed in the effects of HTHQ on the fibrosis.     

Hydrogen‐rich saline protects against liver injury in rats with obstructive jaundice

Background: Hydrogen selectively reduces levels of hydroxyl radicals and alleviates acute oxidative stress in many models. Hydrogen‐rich saline provides a high concentration of hydrogen that can be easily and safely applied. Aims: In this study, we investigated the effects of hydrogen‐rich saline on the prevention of liver injury induced by obstructive jaundice in rats. Methods: Male Sprague–Dawley rats (n=56) were divided randomly into four experimental groups: sham operated, bile duct ligation (BDL) plus saline treatment [5 ml/kg, intraperitoneal (i.p.)], BDL plus low‐dose hydrogen‐rich saline treatment (5 ml/kg, i.p.) and BDL plus high‐dose hydrogen‐rich saline treatment (10 ml/kg, i.p.). Results: The liver damage was evaluated microscopically 10 days after BDL. Serum alanine aminotransferase and aspartate aminotransferase levels, tissue malondialdehyde content, myeloperoxidase activity, tumour necrosis factor‐α, interleukin (IL)‐1β, IL‐6 and high‐mobility group box 1 levels were all increased significantly by BDL. Hydrogen‐rich saline reduced levels of these markers and relieved morphological liver injury. Additionally, hydrogen‐rich saline markedly increased the activities of anti‐oxidant enzymes superoxide dismutase and catalase and downregulated extracellular signal‐regulated protein kinase (ERK)1/2 activation. Conclusions: Hydrogen‐rich saline attenuates BDL‐induced liver damage, possibly by the reduction of inflammation and oxidative stress and the inhibition of the ERK1/2 pathway.     

Effects of salviainolic acid A (SA‐A) on liver injury: SA‐A action on hepatic peroxidation

Abstract: Background/Aims: This study aimed to investigate the actions of salviainolic acid A (SA‐A), an antiperoxidative component of Salvia miltiorrhiza (Sm), on rat liver injury and fibrosis. Methods: Acute and chronic rat liver injury models were established using carbon tetrachloride (CCl₄). After 48 h (acute) or during 6 weeks of CCl₄ injection, rats were further divided and treated with biphenyl dimethyl‐dicarboxylate (BDD) or colchicine, as a control antifibrotic treatment, with Sm, a herbal compound, or SA‐A, a water‐soluble extract of Sm. Liver function was investigated by assessing alanine transaminase (ALT) and aspartate transaminase (AST) activities, histological analysis, hydroxyproline (Hyp) and malondiadehyde (MDA) content. In vitro, isolated cultured hepatocytes were injured with CCl₄ gas for 24 h, followed by treatment with either vitamin E or various concentrations of SA‐A. The extent of hepatocyte injury was monitored by analyzing various lipid peroxidative parameters such as superoxide dismutase (SOD), glutathione (GSH), catalase (CAT), lactase dehydrogenase (LDH), and glutathione peroxidase (GSH‐PX) levels in hepatocyte supernatants. Results: SA‐A significantly decreased abnormal serum ALT activity both in acutely and chronically injured rat livers, decreased abnormal serum AST activity, Hyp and MDA content and attenuated hepatic collagen deposition. After CCl₄ incubation and injury, the activities of AST, ALT CAT, GSH‐PX and LDH and MDA content in hepatocyte supernatants increased significantly, but GSH levels decreased significantly. SA‐A markedly improved these pathological changes in a dose‐dependent manner. 10^?4 mol/l SA‐A had stronger inhibitory action than vitamin E. Conclusions: Our studies suggest that SA‐A has antiperoxidative effects on injured hepatocytes in liver injury and fibrosis induced by CCl₄.     

Hepatocyte growth factor protects against Fas‐mediated liver apoptosis in transgenic mice

Background: Apoptosis via the Fas/Fas ligand signalling system plays an important role in the development of various liver diseases. The administration of an agonistic anti‐Fas antibody to mice causes massive hepatic apoptosis and fulminant hepatic failure. Several growth factors including hepatocyte growth factor (HGF) have been found to prevent apoptosis. Methods: In this study, we demonstrated the overexpression of HGF to have a protective effect on Fas‐mediated hepatic apoptosis using a transgenic mice (Tg mice) model. Results: In HGF Tg mice, the elevation of alanine aminotransferase was dramatically inhibited at 12 and 24 h after the administration of 0.15 mg/kg anti‐Fas antibody. HGF Tg mice showed a significantly lower number of apoptotic hepatocytes at 12 h compared with wild‐type (WT) mice. Furthermore, 85% (six of seven) HGF Tg mice were able to survive after the administration of 0.3 mg/kg anti‐Fas antibody, while none of the WT mice survived. The Bcl‐xL expression was increased in HGF Tg mice, while there was no difference in the expression of Bax, Bid, Mcl‐1 and bcl‐2 between WT mice and HGF Tg mice. In addition, the HGF Tg mice showed more Akt phosphorylation than the WT mice both before and after the anti‐Fas antibody injection. Conclusions: Taken together, our findings suggest that HGF protects against Fas‐mediated liver apoptosis in vivo, and the upregulation of Bcl‐xL via Akt activation may also play a role in the protective effects of HGF.     

Expression and activity of the cytochrome P450 2E1 in patients with nonalcoholic steatosis and steatohepatitis.

BACKGROUND/AIMS: Nonalcoholic steatohepatitis (NASH) and nonalcoholic fatty liver (NAFL) have a different prognosis and should be dealt with differently. The pathogenesis of NASH implicates the overexpression of cytochrome P450 2E1 (CYP2E1). We investigated whether the noninvasive determination of CYP2E1 activity could replace a liver biopsy in order to differentiate NASH from NAFL. METHOD: Forty patients referred for suspicion of NASH underwent liver biopsy. In these patients, CYP2E1 activity was determined noninvasively by the 6-hydroxychlorzoxazone/chlorzoxazone (CHZ) ratio (CHZ test). Expression of CYP2E1 on liver slides was assessed by immunohistochemistry, and immunostaining for smooth muscle actin was used to assess the activation of hepatic stellate cells (HSC). RESULTS: Thirty patients with NASH were compared with 10 subjects with NAFL. No statistically significant difference could be identified for the clinical and biochemical parameters between the two groups. In the histology, steatosis was more important in NASH than in NAFL (P<0.0001). There was no difference either in the activity (CHZ test) or in the expression of CYP2E1 (immunohistochemistry) between patients with NASH and patients with NAFL. The degree of HSC activation was also comparable between the two groups. A positive and significant correlation was found between the activity of CYP2E1 and body mass index (P<0.001) as well as with the degree of steatosis (P=0.008). CONCLUSION: For patients suspected to have NASH, noninvasive tests including the determination of the CYP2E1 activity are unable to distinguish them from patients with steatosis.     

Microsomal Ethanol‐Oxidizing System: Success Over 50 Years and an Encouraging Future

Fifty years ago, in 1968, the pioneering scientists Charles S. Lieber and Leonore M. DeCarli discovered the capacity for liver microsomes to oxidize ethanol (EtOH) and named it the microsomal ethanol‐oxidizing system (MEOS), which revolutionized clinical and experimental alcohol research. The last 50 years of MEOS are now reviewed and highlighted. Since its discovery and as outlined in a plethora of studies, significant insight was gained regarding the fascinating nature of MEOS: (i) MEOS is distinct from alcohol dehydrogenase and catalase, representing a multienzyme complex with cytochrome P450 (CYP) and its preferred isoenzyme CYP 2E1, NADPH–cytochrome P450 reductase, and phospholipids; (ii) it plays a significant role in alcohol metabolism at high alcohol concentrations and after induction due to prolonged alcohol use; (iii) hydroxyl radicals and superoxide radicals promote microsomal EtOH oxidation, assisted by phospholipid peroxides; (iv) new aspects focus on microsomal oxidative stress through generation of reactive oxygen species (ROS), with intermediates such as hydroxyethyl radical, ethoxy radical, acetyl radical, singlet radical, hydroxyl radical, alkoxyl radical, and peroxyl radical; (v) triggered by CYP 2E1, ROS are involved in the initiation and perpetuation of alcoholic liver injury, consequently shifting the previous nutrition‐based concept to a clear molecular‐based disease; (vi) intestinal CYP 2E1 induction and ROS are involved in endotoxemia, leaky gut, and intestinal microbiome modifications, together with hepatic CYP 2E1 and liver injury; (vii) circulating blood CYP 2E1 exosomes may be of diagnostic value; (viii) circadian rhythms provide high MEOS activities associated with significant alcohol metabolism and potential toxicity risks as a largely neglected topic; and (ix) a variety of genetic animal models are useful and have been applied elucidating mechanistic aspects of MEOS. In essence, MEOS along with its CYP 2E1 component currently explains several mechanistic steps leading to alcoholic liver injury and has a promising future in alcohol research.     

Induction of cytochrome P450 2E1 [corrected] promotes liver injury in ob/ob mice

Cytochrome P450 2E1 (CYP2E1) activates several hepatotoxins and contributes to alcoholic liver damage. Obesity is a growing health problem in the United States. The aim of the present study was to evaluate whether acetone- or pyrazole-mediated induction of CYP2E1 can potentiate liver injury in obesity. CYP2E1 protein and activity were elevated in acetone- or pyrazole-treated obese and lean mice. Acetone or pyrazole induced distinct histological changes in liver and significantly higher aminotransferase enzymes in obese mice compared to obese controls or acetone- or pyrazole-treated lean mice. Higher caspase-3 activity and numerous apoptotic hepatocytes were observed in the acetone- or pyrazole-treated obese mice. Increased protein carbonyls, malondialdehyde, 4-hydroxynonenal-protein adducts, elevated levels of inducible nitric oxide synthase, and higher 3-nitrotyrosine protein adducts were found in livers of acetone- or pyrazole-treated obese animals, suggesting elevated oxidative and nitrosative stress. Liver tumor necrosis factor alpha levels were higher in pyrazole-treated animals. The CYP2E1 inhibitor chlormethiazole and iNOS inhibitor N-(3-(aminomethyl)-benzyl) acetamidine abrogated the toxicity and the oxidative/nitrosative stress elicited by the induction of CYP2E1. CONCLUSION: These results show that obesity contributes to oxidative stress and liver injury and that induction of CYP2E1 enhances these effects.     

Acetaminophen‐induced liver injury in obesity and nonalcoholic fatty liver disease

Although acetaminophen (APAP) is usually considered as a safe drug, this painkiller can lead to acute liver failure after overdoses. Moreover, there is evidence that the maximum recommended dosage can induce hepatic cytolysis in some individuals. Several predisposing factors appear to enhance the risk and severity of APAP‐induced liver injury including chronic alcoholic liver disease and nonalcoholic fatty liver disease (NAFLD), which refers to a large spectrum of hepatic lesions linked to obesity. In contrast, obesity by itself does not seem to be associated with a higher risk of APAP‐induced liver injury. Since 1987, seven studies dealt with APAP‐induced hepatotoxicity in rodent models of NAFLD and five of them found that this liver disease was associated with higher APAP toxicity. Unfortunately, these studies did not unequivocally established the mechanism(s) whereby NAFLD could favour APAP hepatotoxicity, although some investigations suggested that pre‐existent induction of hepatic cytochrome P450 2E1 (CYP2E1) could play a significant role by increasing the generation of N‐acetyl‐p‐benzoquinone imine (NAPQI), the toxic metabolite of APAP. Moreover, pre‐existent mitochondrial dysfunction associated with NAFLD could also be involved. In contrast, some investigations suggested that factors that could reduce the risk and severity of APAP hepatotoxicity in obesity and NAFLD include higher hepatic APAP glucuronidation, reduced CYP3A4 activity and increased volume of body distribution. Thus, the occurrence and the outcome of APAP‐induced liver injury in an obese individual with NAFLD might depend on a delicate balance between metabolic factors that can be protective and others that favour large hepatic levels of NAPQI.     

Anti‐envelope antibody responses in individuals at high risk of hepatitis C virus who resist infection

Injection drug users uninfected by hepatitis C virus (HCV) despite likely repeated exposure through high‐risk behaviour are well documented. Factors preventing infection in these individuals are incompletely understood. Here, we looked for anti‐HCV‐envelope antibody responses in a cohort of repeatedly exposed but uninfected subjects. Forty‐two hepatitis C diagnostic antibody‐ and RNA‐negative injection drug users at high risk of exposure were studied and findings compared to healthy controls and cases with chronic HCV infection. Purified IgGs from sera were tested by ELISA for binding to genotype 1a and 3a envelope glycoproteins E1E2 with further testing for IgG and IgM reactivity against soluble E2. Virus‐neutralizing activity was assessed using an HCV pseudoparticle system. Uninfected subjects demonstrated significantly greater IgG and IgM reactivities to envelope glycoproteins than healthy controls with IgG from 6 individuals additionally showing significant neutralization. This study is the first to describe humoral immunological responses targeting the HCV envelope, important for viral neutralization, in exposed uninfected individuals. A subset of these cases also had evidence of viral neutralization via anti‐envelope antibodies. In addition to confirming viral exposure, the presence of specific anti‐envelope antibodies may be a factor that helps these individuals resist HCV infection.     

Protection against liver injury by PGE1 or anti‐TNF‐α is associated with a reduction of TNF‐R1 expression in hepatocytes

Background: Tumour necrosis factor‐α (TNF‐α) has been shown to exacerbate or protect against liver injury in different experimental models. In a previous study, we observed that enhancement of TNF‐α expression in hepatocytes by prostaglandin E ₁ (PGE ₁ ) pre‐administration induced iNOS expression and cytoprotection against experimental liver injury in rats. Nevertheless, the reduction of TNF‐α bioactivity by anti‐TNF‐α antibodies also reduced liver injury by D‐GalN. The purpose of the present study was to evaluate whether protection by PGE ₁ or anti‐TNF‐α was related to a common effect on the membrane‐bound TNF‐α receptor expression. Methods: Liver injury was induced in male Wistar rats by intraperitoneal injection of D‐galactosamine (D‐GalN) (1?g/kg). PGE ₁ or anti‐TNF‐α was administered at 30 or 60?min before D‐GalN, respectively. Liver injury was evaluated by alanine aminotransferase (ALT) activity in serum and histological examination in liver sections. TNF‐αwas determined by ELISA in serum. The expression of TNF‐α receptor type 1 (TNF‐R1) and TNF‐α receptor type 2 (TNF‐R2) in hepatocytes was assessed by immunohistochemistry and immunoprecipitation?+?Western‐blot analysis. Results: PGE ₁ or anti‐TNF‐α reduced liver injury induced by D‐GalN. Although PGE ₁ enhanced and anti‐TNF‐α reduced TNF‐α concentration in serum, both protective treatments reduced the expression of TNF‐R1 in hepatocytes. TNF‐R2 was not detected in our experimental conditions. Conclusions: Our study showed that reduction of liver injury by PGE ₁ or anti‐TNF‐α antibodies was related to a reduction of TNF‐R1 expression in hepatocytes.     

普洱茶(熟茶)茶粉、黑茶茶粉、六堡茶对非酒精性脂肪肝大鼠肝细胞CYP2E1表达的影响

背景:CYP2E1是一种可被乙醇诱导的细胞色素P450酶。在非酒精性脂肪性肝病发病机制的"二次打击"学说中,CYP2E1介导的脂质过氧化发挥重要作用。目的:从改善氧化应激的角度探讨普洱茶(熟茶)茶粉、黑茶茶粉和六堡茶对非酒精性脂肪肝(NAFL)模型大鼠的辅助保护作用。方法:120只Wistar大鼠分为正常对照组、高脂模型组、降脂药物组以及低、中、高剂量(0.5、1.0、2.0 g/kg)普洱茶(熟茶)茶粉、黑茶茶粉、六堡茶组。以高脂饮食诱导NAFL模型,实验组予相应品种、剂量的茶汤灌胃35 d。处死大鼠,测定肝组织抗氧化指标,real time PCR检测肝细胞CYP2E1 mRNA表达,同时观察肝脏组织学表现。结果:适宜剂量的普洱茶(熟茶)茶粉和六堡茶能显著降低高脂模型大鼠的肝组织MDA含量,增高SOD、GSH-Px活性,抑制肝细胞CYP2E1 mRNA表达(P均<0.05)。高剂量六堡茶组肝脏组织学表现为轻度脂肪肝,高剂量普洱茶(熟茶)茶粉组和黑茶茶粉组表现为中度脂肪肝。结论:普洱茶(熟茶)茶粉和六堡茶对NAFL大鼠模型的肝脏抗氧化指标、CYP2E1基因表达和组织学表现具有积极作用,表明两者对NAFLD可发挥辅助保护作用,六堡茶的作用更为明显。     

Attenuation of N-nitrosodiethylamine-induced liver fibrosis by high-molecular-weight fucoidan derived from Cladosiphon okamuranus

Background and Aim: Liver fibrosis is closely associated with the progression of various chronic liver diseases. Fucoidan exhibits different biological properties such as anti‐inflammatory, anti‐oxidant and anti‐fibrotic activities. The aim of this study was to determine whether oral fucoidan administration inhibits N‐nitrosodiethylamine (DEN)‐induced liver fibrosis. Methods: Liver fibrosis was induced in rats by injecting DEN (50 mg/kg). Rats were given 2% of crude fucoidan solution or 2% of high‐molecular‐weight (HMW) fucoidan solution. They were divided into a crude fucoidan group, an HMW fucoidan group, a DEN alone group, a DEN + crude fucoidan group, a DEN + HMW fucoidan group and a control group. Results: Liver fibrosis and hepatic hydroxyproline levels were significantly more decreased in the DEN + HMW fucoidan group than in the DEN‐alone group. Anti‐fibrogenesis was unremarkable in the DEN + crude fucoidan group. Hepatic messenger RNA levels and immunohistochemistry of transforming growth factor beta 1 were markedly increased by DEN. This increase was attenuated by HMW fucoidan. Hepatic chemokine ligand 12 expression was increased by DEN. This increase was suppressed by HMW fucoidan. HMW fucoidan significantly decreased the DEN‐induced malondialdehyde levels. Also, fucoidan markedly increased metallothionein expression in the liver. Fucoidan was clearly observed in the liver by immunohistochemical staining in HMW fucoidan‐treated rats, while it was faintly stained in the livers of crude fucoidan‐treated rats. Conclusion: These findings suggest that the HMW fucoidan treatment causes anti‐fibrogenesis in DEN‐induced liver cirrhosis through the downregulation of transforming growth factor beta 1 and chemokine ligand 12 expressions, and that scavenging lipid peroxidation is well‐incorporated in the liver.     

Associations of HLA‐DRB1 alleles with anti‐citrullinated protein antibody‐positive and anti‐citrullinated protein antibody‐negative rheumatoid arthritis in northern east part of Turkey

Aim: The aim of this study was to investigate the associations between human leukocyte antigen (HLA)‐DRB1 alleles with genetic susceptibility to rheumatoid arthritis (RA) and production of antibodies against cyclic citrullinated peptide (anti‐CCP antibody) and rheumatoid factor (RF) in Turkish RA patients. Methods: We studied 291 RA patients and 253 controls. Genotyping was performed by polymerase chain reaction with sequence‐specific oligonucleotide probes hybridization method. Serum levels of anti‐CCP antibody, IgM‐RF and high sensitive C‐reactive protein titers were measured by commercial kits using immunological methods. Results: We found that HLA‐DRB1*04 and *09 alleles were associated in anti‐CCP+ and anti‐CCP+ RA patients (P < 0.0001 and P < 0.001, respectively), while DRB1*01 and *04 were determined to be higher in RF+ RA patients (P < 0.001 and P < 0.0001, respectively). Moreover, DRB1*11 and DRB1*13 alleles were determined to be lower in RF and anti‐CCP/RF+ RA patients (P < 0.001 for both). HLA‐DRB1*04 was identified as a common responsible allele for susceptibility to the disease in anti‐CCP, RF and anti‐CCP/RF? RA patients (P = 0.0018, P = 0.0004 and P = 0.0023, respectively). HLA‐DRB1*13 allele alone was found to be protective against to anti‐CCP+ and RF? RA (P = 0.0003 and P = 0.006, respectively). On the contrary, there was no protective allele in anti‐CCP/RF? RA as well as anti‐CCP? RA patients. Conclusion: This study indicates that associate and protective HLA‐DRB1 allele distributions are different in autoantibody (anti‐CCP or RF or anti‐CCP/RF)+ RA and autoantibody? RA patients, with exceptions of DRB1*04 and DRB1*13.     

Cross‐genotype‐specific T‐cell responses in acute hepatitis E virus (HEV) infection

Hepatitis E is an inflammatory liver disease caused by infection with the hepatitis E virus (HEV). In tropical regions, HEV is highly endemic and predominantly mediated by HEV genotypes 1 and 2 with >3 million symptomatic cases per year and around 70 000 deaths. In Europe and America, the zoonotic HEV genotypes 3 and 4 have been reported with continues increasing new infections per year. So far, little is known about T‐cell responses during acute HEV genotype 3 infection. Therefore, we did a comprehensive study investigating HEV‐specific T‐cell responses using genotypes 3‐ and 1‐specific overlapping peptides. Additional cytokines and chemokines were measured in the plasma. In four patients, longitudinal studies were performed. Broad functional HEV‐specific CD4⁺ and CD8⁺ T‐cell responses were detectable in patients acutely infected with HEV genotype 3. Elevated of pro‐ and anti‐inflammatory cytokine levels during acute HEV infection correlated with ALT levels. Memory HEV‐specific T‐cell responses were detectable up to >1.5 years upon infection. Importantly, cross‐genotype HEV‐specific T‐cell responses (between genotypes 1 and 3) were measurable in all investigated patients. In conclusion, we could show for the first time HEV‐specific T‐cell responses during and after acute HEV genotype 3 infection. Our data of cross‐genotype HEV‐specific T‐cell responses might suggest a potential role in cross‐genotype‐specific protection between HEV genotypes 1 and 3.     

Microsomal Ethanol-Oxidizing System (MEOS): The First 30 Years (1968-1998)–A Review

Oxidation of ethanol via alcohol dehydrogenase (ADH) explains various metabolic effects of ethanol but does not account for the tolerance and a number of associated disorders that develop in the alcoholic. These were elucidated by the discovery of the microsomal metabolism of ethanol. The physiologic role of this system comprises gluconeogenesis from ketones, fatty acid metabolism, and detoxification of xenobiotics, including ethanol. After chronic ethanol consumption, the activity of the microsomal ethanol-oxidizing system (MEOS) increases, with an associated rise in cytochromes P-450, especially CYP2E1. This induction is associated with proliferation of the endoplasmic reticulum, both in experimental animals and in humans. The role of MEOS in vivo and its increase after chronic ethanol consumption was shown most conclusively in alcohol dehydrogenase-negative deer mice. Enhanced ethanol oxidation is associated with cross-induction of the metabolism of other drugs, resulting in drug tolerance. Furthermore, there is increased conversion of known hepatotoxic agents (such as CCl₄) to toxic metabolites, which may explain the enhanced susceptibility of alcoholics to the adverse effects of industrial solvents. CYP2E1 also has a high capacity to activate some commonly used drugs, such as acetaminophen, to their toxic metabolites, and to promote carcinogenesis (e.g., from dimethylnitrosamine). Moreover, catabolism of retinol is accelerated and there also is induction of microsomal enzymes involved in lipoprotein production, resulting in hyperlipemia. Contrasting with the chronic effects of ethanol consumption, acute ethanol intake inhibits the metabolism of other drugs through competition for the at least partially shared microsomal pathway. In addition, metabolism by CYP2E1 results in a significant free radical release and acetaldehyde production which, in turn, diminish reduced glutathione (GSH) and other defense systems against oxidative stress. Acetaldehyde also forms adducts with proteins, thereby altering the functions of mitochondria and of repair enzymes. Increases of CYP2E1 and its mRNA prevail in the perivenular zone, the area of maximal liver damage. CYP1A2 and CYP3A4, two other perivenular P-450s, can also sustain the metabolism of ethanol, thereby contributing to MEOS activity and possibly liver injury. By contrast, CYP2E1 inhibitors oppose alcohol-induced liver damage, but heretofore available compounds were too toxic for clinical use. Recently, however, polyenylphosphatidylcholine (PPC), an innocuous mixture of polyunsaturated lecithins extracted from soybeans, was discovered to decrease CYP2E1 activity. PPC (and its active component dilino-leoylphosphatidylcholine) also oppose hepatic oxidative stress and fibrosis. PPC is now being tested clinically for the prevention and treatment of liver disease in the alcoholic.