Marilena Durazzo

Adipokines in NASH: Postprandial lipid metabolism as a link between adiponectin and liver disease†

Circulating levels of four adipokines (adiponectin, TNF‐α, leptin, and resistin) and the postprandial lipid and adiponectin responses to an oral fat load were assessed in 25 non‐obese, non‐diabetic patients with biopsy‐proven nonalcoholic steatohepatitis (NASH) and correlated with metabolic indices and liver histology. Circulating adiponectin was lower in NASH compared with controls (5,476 ± 344 vs. 11,548 ± 836 ng/mL; P = .00001) and on multiple regression analysis correlated negatively with liver steatosis, necroinflammation (OR = 5.0; P = .009), and fibrosis (OR = 8.0; P = .003).The magnitude of postprandial lipemia was significantly higher in NASH than in controls and was related to fasting adiponectin (β = −0.78; P = .00003). Controls showed a significant increase in serum adiponectin in response to the fat load, whereas patients with NASH showed a slight decrease. Postprandial free fatty acids response correlated inversely with adiponectin response in both groups and independently predicted the severity of liver steatosis in NASH (β = 0.51; P = .031). In conclusion, hypoadiponectinemia is present before overt diabetes and obesity appear and correlates with the severity of liver histology in NASH. Impaired postprandial lipid metabolism may be an additional mechanism linking hypoadiponectinemia and NASH and posing a higher cardiovascular risk to these subjects. The mechanism(s) underlying these differences are unknown, but the type of dietary fat seems to play a role. These findings may have important pathogenetic and therapeutic implications in both liver and metabolic disease. (HEPATOLOGY 2005.)

Hypoadiponectinemia Predicts the Severity of Hepatic Fibrosis and Pancreatic Beta-Cell Dysfunction in Nondiabetic Nonobese Patients with Nonalcoholic Steatohepatitis

OBJECTIVES:The relationships between the adipokines tumor necrosis factor (TNF)-α and adiponectin and the parameters of glucose homeostasis and severity of liver disease were assessed in nonobese nondiabetic subjects with nonalcoholic steatohepatitis (NASH).METHODS:A frequently sampled intravenous glucose tolerance test, serum cytokine measurement, and 7-day alimentary record were performed in 20 biopsy-proven NASH patients and 45 age-, sex-, and BMI-matched controls (30 insulin sensitive and 15 insulin resistant).RESULTS:Patients with NASH had impaired pancreatic β-cell function compared with both insulin-sensitive (adaptation index, AI: 97.7 ± 17.7 vs 307.4 ± 24.1 min−2 mmol−1 L; p = 0.00001) and insulin-resistant (adaptation index, AI: 97.7 ± 17.7 vs 201.4 ± 41.1 min−2 mmol−1 L; p = 0.001) controls. Serum adiponectin levels were also significantly lower in the NASH group than in the two control groups and correlated with adaptation index and with the severity of hepatic steatosis, necroinflammation, and fibrosis. When NASH patients were grouped according to the severity of histological liver damage, adiponectin was the only variable discriminating patients with higher necroinflammatory grade and fibrosis score from those with milder lesions.CONCLUSIONS:β-cell secretory impairment is present in nonobese patients with NASH before glucose intolerance appears and may contribute to their increased risk for developing diabetes. Hypoadiponectinemia is a feature of NASH and may have a pathogenetic role in β-cell dysfunction and in hepatic necroinflammation and fibrosis, independently of insulin resistance, visceral fat accumulation, TNF-α axis activity, and dietary habits. Our findings provide further rationale for therapeutic approaches aimed at increasing adiponectin levels together with restoring β-cell function and insulin sensitivity.

Polymorphism in microsomal triglyceride transfer protein: A link between liver disease and atherogenic postprandial lipid profile in NASH?†

Nonalcoholic fatty liver disease (NAFLD) is emerging as an independent cardiovascular risk factor, but mechanism(s) linking fatty liver to atherosclerosis are unknown. Microsomal triglyceride transfer protein (MTP) −493 G/T polymorphism modulates circulating lipid and lipoprotein levels in different subsets and has been linked to NAFLD. The impact of MTP −493 G/T polymorphism, adipokines, and diet on postprandial lipoprotein profile and liver disease was assessed in nonalcoholic steatohepatitis (NASH). Plasma lipids, triglyceride‐rich lipoprotein subfractions, high‐density lipoprotein‐C (HDL‐C), and oxidized low‐density lipoprotein (LDL) after an oral fat load were cross‐sectionally correlated to MTP −493 G/T polymorphism, dietary habits, adipokines, and liver histology in 29 nonobese nondiabetic patients with NASH and 27 healthy controls. The severity of liver histology, the magnitude of triglycerides (Tg), free fatty acid (FFA), and LDL‐conjugated diene responses, and the fall in HDL‐C and apoA1 were significantly higher in NASH G/G (66% of patients) than in the other genotypes, despite similar adipokine profile and degree of insulin resistance. Postprandial large intestinal very‐low‐density lipoprotein (VLDL) subfraction A increases independently predicted Tg (β = 0.48; P = .008), FFA (β = 0.47; P = 0.010), HDL‐C (β = 0.42; P = 0.009), and LDL‐conjugated diene (β = 0.52; P = 0.002) responses. VLDL A apoB48 response was independently associated with liver steatosis (OR: 2.4; CI 1.7‐9.6; P = 0.031). Postprandial LDL‐conjugated diene response predicted severe necroinflammation (OR: 3.3; CI 1.4‐9.7; P = 0.016) and fibrosis (OR: 2.8; CI 1.0‐8,5; P = 0.030); postprandial apoA1 fall predicts severe fibrosis (OR: 2.1; CI: 1.5‐6.1; P = 0.015). Conclusion: MTP ‐493 G/T polymorphism may impact NASH by modulating postprandial lipemia and lipoprotein metabolism; homozygous GG carriers have a more atherogenic postprandial lipid profile than the other genotypes, independently of adipokines and insulin resistance. (HEPATOLOGY 2007;45:1097–1107.)

Adiponectin gene polymorphisms modulate acute adiponectin response to dietary fat: Possible pathogenetic role in NASH

Factors underlying the independent association of nonalcoholic steatohepatitis (NASH) with increased cardiovascular risk are unknown. Adiponectin polymorphisms predict cardiometabolic risk in the general population. This association is not always mediated by low fasting adiponectin levels, adipose tissue accumulation, or traditional risk factors. Adiponectin modulates lipid metabolism and liver injury in nonalcoholic fatty liver disease (NAFLD) even in the absence of obesity, dyslipidemia, and diabetes. We hypothesized adiponectin polymorphisms may predispose to NAFLD and may increase cardiovascular risk by modulating circulating lipoprotein and adiponectin response postprandially. The prevalence of adiponectin single‐nucleotide polymorphisms (SNPs) 45GT and 276GT was assessed in 70 nonobese, nondiabetic, normolipidemic NAFLD patients and 70 healthy matched controls; the impact of the adiponectin SNPs was subsequently correlated to liver histology and postprandial adiponectin and lipoprotein responses to oral fat load in a subgroup of 30 biopsy‐proven patients with NASH and 30 controls. The 45TT and 276GT/TT genotypes were more prevalent in NAFLD patients than in controls and independently predicted the severity of liver disease in NASH. In both patients and controls, these genotypes exhibited a blunted postprandial adiponectin response and higher postprandial triglycerides (Tg), free fatty acids (FFA), oxidized LDL (oxLDL), and VLDL levels than their counterparts, despite comparable fasting adipokines, lipids, dietary habits, adiposity, and insulin resistance. They were also independently associated, together with dietary polyunsaturated fatty acid intake, with postprandial adiponectin response. IAUC adiponectin independently predicted postprandial Tg, FFA, oxLDL, and intestinal and hepatic VLDL subfraction responses in NASH. Conclusion: The at‐risk adiponectin SNPs 45TT and 276GT are significantly more prevalent in NAFLD than in the general population; they are associated with severity of liver disease, with blunted postprandial adiponectin response, and with an atherogenic postprandial lipoprotein profile in NASH independently of fasting adipokine and lipid levels. (HEPATOLOGY 2008.)

Analysis of hepatitis C virus genome in patients with autoimmune hepatitis type 2

BACKGROUND/AIMS Hepatitis C virus (HCV) RNA is detectable in a proportion of patients with autoimmune hepatitis type 2, which is characterized by liver-kidney microsomal antibodies (LKM). Therefore, the genotype and sequence of HCV were studied in these patients. METHODS Sera from 43 LKM-positive and anti-HCV-positive patients (15 from Germany and 28 from Italy) and 82 LKM-negative and anti-HCV-positive patients (57 from Germany and 25 from Italy) were examined. RESULTS Genotyping revealed that the rate of genotype III HCV according to Okamotos classification in patients with LKM antibody-positive autoimmune hepatitis type 2 was higher than in LKM-negative patients (22.0% vs. 2.4%; P < 0.05). This was because of an increase of genotype III in our patients from Italy. No HCV mutations were found that show a closer sequence homology to cytochrome P450IID6, the major LKM-1 antigen. Deletions in the envelope and nonstructural region 5 were found. CONCLUSIONS Because a specific HCV sequence is not associated with the induction of LKM-1 autoantibodies, future research must focus on host factors and possibly additional environmental factors.

Hepatitis C virus-related chronic liver disease with autoantibodies to liver-kidney microsomes (LKM): Clinical characterization from idiopathic LKM-positive disorders

This study was carried out on 33 patients who were sero-positive for liver-kidney microsomal antibodies (LKM) in order to examine clinical features and the presence of underlying hepatitis C virus infection. Twenty-four sera were positive for antibodies against HCV (anti-HCV) as detected by enzyme immunoassay and confirmed by recombinant immunoblot assay. These patients had chronic liver disease and the majority of those treated with interferon responded favourably. Three of the nine anti-HCV-negative patients had idiopathic chronic hepatitis and two responded favourably to steroids. Two patients were diagnosed as having toxic hepatitis and the other four had various extrahepatic disorders without evidence of liver involvement. The immunoblotting analysis showed reactivity with a 50 kDa microsomal protein which presumably corresponded to cytochrome P-450 db1 both in anti-HCV-positive and -negative sera. In addition a few anti-HCV-positive sera also reacted with a 35 kDa microsomal antigen. Autoimmune markers different from LKM were absent in both groups. The high prevalence of antibodies to the hepatitis C virus among LKM-positive sera confirms that this infection plays a role in forms of chronic hepatitis that had previously been labelled autoimmune. In patients with LKM the presence of anti-HCV may help to forecast a therapeutic response to interferon, while its absence may forecast response to steroid therapy.

Type I autoimmune hepatitis: clinical course and outcome in an Italian multicentre study

Background  Many reports of autoimmune hepatitis (AIH) were written in the ‘pre‐Hepatitis C era’ and data on the natural history are still incomplete.

Autoantibodies and response to α-interferon in patients with chronic viral hepatitis

One hundred and fifteen patients with chronic type B, D and non-A, non-B hepatitis treated with recombinant alpha-interferon were tested for six different autoantibodies prior to or during therapy, and the course of treatment was compared in autoantibody-positive and -negative patients. Three out of 25 (12%) hepatitis B patients, 14 out of 30 (47%) hepatitis D patients and 19 out of 60 (32%) chronic non-A, non-B hepatitis carriers had baseline or post-therapy autoantibodies. The rate of response between patients with and without autoantibodies among B, D and non-A, non-B patients was, respectively, 67 vs. 79%, 23 vs. 25%, 70 vs. 61% (p = N.S.). No adverse reaction was observed in the 36 patients who had or developed nuclear, smooth muscle, parietal cells and thyroid autoantibodies during therapy. A patient with baseline antibodies against liver and kidney microsomes developed an icteric acute hepatitis at the fourth month of therapy, but five other patients with this reactivity responded to therapy uneventfully. The presence of autoantibodies before therapy or their induction following therapy is not a contraindication to the use of interferon in patients with chronic viral hepatitis.

Transcription factor 7-like 2 polymorphism modulates glucose and lipid homeostasis, adipokine profile, and hepatocyte apoptosis in NASH

Genetic factors underlying the association of NAFLD with diabetes and atherosclerosis are unknown. Recent human studies suggest transcription factor 7–like 2 (TCF7L2) polymorphism predisposes to diabetes through modulation of β‐cell function and modulates lipid levels in familial dyslipidemia. Emerging experimental evidence connects TCF7L2 to adipocyte metabolism and lipid homeostasis, as well. We tested if TCF7L2 polymorphism is a risk factor for nonalcoholic fatty liver disease (NAFLD) and if it modulates liver injury, glucose homeostasis, lipoprotein, and adipokine profiles in NASH. TCF7L2 genotype and dietary habits of 78 nondiabetic normolipidemic NAFLD subjects and 156 age‐, body mass index–, sex‐matched healthy controls were assessed. In 39 biopsy‐proven nonalcoholic steatohepatitis (NASH) and matched controls TCF7L2 polymorphism was correlated to liver histology and oral glucose tolerance test–derived parameters of glucose homeostasis. Patients with NASH and controls consumed a high‐fat meal and TCF7L2 genotype was correlated to postprandial circulating lipoproteins, adipokines, and cytokeratin‐18 fragments. The TCF7L2 CT/TT genotype was more frequent in NAFLD and predicted the presence and severity of liver disease, of β‐cell dysfunction, of reduced incretin effect and hepatic insulin resistance in NASH; it also modulated postprandial hepatocyte apoptosis, lipoproteins, and adipokine profiles in both groups. Conclusion: TCF7L2 polymorphism predisposes to NAFLD and significantly impacts liver injury, glucose homeostasis, and postprandial lipoprotein and adipokine responses to fat ingestion. This polymorphism also modulates a fat‐induced increase in circulating markers of hepatocyte apoptosis in NASH. Targeting postprandial lipemia, at least in at‐risk TCF7L2 genotypes, may improve liver disease and glucose dysmetabolism in these patients. (HEPATOLOGY 2008.)

Intrafamilial transmission of hepatitis delta virus: molecular evidence

BACKGROUND/AIMS Epidemiologic studies have suggested that transmission of hepatitis delta virus (HDV) occurs by intrafamilial routes in some populations in southern Italy, where HDV infection is endemic. To further evaluate intrafamilial transmission of HDV, we obtained the partial sequence of the viral genome from HDV-RNA positive members of families in which two or more immediate family members were positive for HDV-RNA. METHODS The region analyzed was the semi-conserved region from nucleotides 908 to 1265. Sequences obtained from family members were compared with those obtained from a control group of 20 unrelated patients. RESULTS The mean genetic divergence among HDV isolates was 2.8 +/- 1.7% within the 9 families analyzed, and 7.6 +/- 2.2% among the control group of unrelated individuals (p < 0.0001). A Receiver Operating Characteristic curve and Youden Index were used to define a cut-off value of 3.5% to discriminate sequence variations calculated within families and in the control group. CONCLUSIONS The data indicate that in most family units, HDV-infected members harbored nearly identical strains of HDV, and provide molecular support that HDV infection can be transmitted within the family. Such spreading among family members highlights the role of inapparent transmission through personal contacts.