Lean NAFLD: A Distinct Entity Shaped by Differential Metabolic Adaptation.

BACKGROUND AND AIMS: Nonalcoholic fatty liver disease (NAFLD) affects a quarter of the adult population. A significant subset of patients are lean, but their underlying pathophysiology is not well understood. APPROACH AND RESULTS: We investigated the role of bile acids (BAs) and the gut microbiome in the pathogenesis of lean NAFLD. BA and fibroblast growth factor (FGF) 19 levels (a surrogate for intestinal farnesoid X receptor [FXR] activity), patatin-like phospholipase domain containing 3 (PNPLA3), and transmembrane 6 superfamily member 2 (TM6SF2) variants, and gut microbiota profiles in lean and nonlean NAFLD were investigated in a cohort of Caucasian patients with biopsy-proven NAFLD (n = 538), lean healthy controls (n = 30), and experimental murine models. Patients with lean NAFLD had a more favorable metabolic and histological profile compared with those with nonlean NAFLD (P < 0.05 for all). BA levels were significantly higher in NAFLD with advanced compared with earlier stages of liver fibrosis. Patients with lean NAFLD had higher serum secondary BA and FGF19 levels and reduced 7-alpha-hydroxy-4-cholesten-3-one (C4) levels (P < 0.05 for all). These differences were more profound in early compared with advanced stages of fibrosis (P < 0.05 for both). Lean patients demonstrated an altered gut microbiota profile. Similar findings were demonstrated in lean and nonlean murine models of NAFLD. Treating mice with an apical sodium-dependent BA transporter inhibitor (SC-435) resulted in marked increases in fgf15, a shift in the BA and microbiota profiles, and improved steatohepatitis in the lean model. CONCLUSIONS: Differences in metabolic adaptation between patients with lean and nonlean NAFLD, at least in part, explain the pathophysiology and provide options for therapy.

Crosstalk between adipose tissue insulin resistance and liver macrophages in non-alcoholic fatty liver disease.

BACKGROUND & AIMS: The pathogenesis of non-alcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) is likely due to the interaction between a deranged metabolic milieu and local mediators of hepatic inflammation and fibrosis. We undertook this study to elucidate the interplay between macrophage activation, insulin resistance (IR) in target organs/tissues and hepatic damage. METHODS: In 40 non-diabetic patients with biopsy-proven NAFLD we assessed: i) endogenous glucose production (EGP), glucose clearance and indexes of IR in the adipose tissue (Adipo-IR and Lipo-IR) and in the liver (Hep-IR) by tracer infusion ([6,6-2H2]glucose and [2H5]glycerol); ii) macrophage activity (by soluble sCD163) and iii) hepatic expression of CD163 (hCD163). RESULTS: We found that sCD163 levels paralleled both the plasma free fatty acid (FFA) levels and lipolysis from adipose tissue. Consistently, sCD163 significantly correlated with adipose tissue IR (Adipo-IR: r = 0.32, p = 0.042; Lipo-IR: r = 0.39, p = 0.012). At multiple regression analysis, sCD163 levels were associated with FFA levels (rp = 0.35, p = 0.026). In vitro exposure of human monocyte-derived macrophages to palmitate enhanced sCD163 secretion. Conversely, sCD163 did not correlate with EGP or with Hep-IR. In the liver, hCD163 positively correlated with sCD163 (r = 0.58, p = 0.007) and the degree of steatosis (r = 0.34, p = 0.048), but not with EGP or Hep-IR (r = -0.27 and r = 0.11, respectively, p >0.10, both). CONCLUSIONS: Our findings suggest a link between deranged metabolism in the adipose tissue and activation of hepatic macrophages in patients with NAFLD, possibly in response to FFA overflow and independent of obesity and diabetes. Conversely, our findings do not support a link between activated hepatic macrophages and glucose metabolism (EGP or Hep-IR). The relationship between adipose tissue IR and hepatic macrophages should be considered to define therapeutic targets for NAFLD. LAY SUMMARY: The pathogenesis of non-alcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) is likely due to the interaction between a deranged metabolic milieu and local mediators of hepatic inflammation and fibrosis in the insulin resistant state. This study provides in vivo support for a possible link between deranged metabolism in the adipose tissue and activation of hepatic macrophages in patients with NAFLD, most likely in response to free fatty acid overflow and independent of obesity and diabetes.

Adiponectin confers protection from acute colitis and restricts a B cell immune response.

Adiponectin demonstrates beneficial effects in various metabolic diseases, including diabetes, and in bowel cancer. Recent data also suggest a protective role in colitis. However, the precise molecular mechanisms by which adiponectin and its receptors modulate colitis and the nature of the adaptive immune response in murine models are yet to be elucidated. Adiponectin knock-out mice were orally administered dextran sulfate sodium for 7 days and were compared with wild-type mice. The severity of disease was analyzed histopathologically and through cytokine profiling. HCT116 colonic epithelial cells were employed to analyze the in vitro effects of adiponectin and AdipoR1 interactions in colonic injury following dextran sulfate sodium treatment. Adiponectin knock-out mice receiving dextran sulfate sodium exhibited severe colitis, had greater inflammatory cell infiltration, and an increased presence of activated B cells compared with controls. This was accompanied by an exaggerated proinflammatory cytokine profile and increased STAT3 signaling. Adiponectin knock-out mouse colons had markedly reduced proliferation and increased epithelial apoptosis and cellular stress. In vitro, adiponectin reduced apoptotic, anti-proliferative, and stress signals and restored STAT3 signaling. Following the abrogation of AdipoR1 in vitro, these protective effects of adiponectin were abolished. In summary, adiponectin maintains intestinal homeostasis and protects against murine colitis through interactions with its receptor AdipoR1 and by modulating adaptive immunity.

The macrophage activation marker sCD163 is associated with morphological disease stages in patients with non-alcoholic fatty liver disease.

BACKGROUND & AIMS: Macrophage activation plays a key pathogenic role in experimental non-alcoholic fatty liver disease (NAFLD) and contributes to the progression of steatohepatitis (NASH) and fibrosis. We studied macrophage activation in human NAFLD by measuring soluble (s)CD163, a specific macrophage activation marker, hypothesizing that sCD163 would be associated with the patients' morphological disease grade. Furthermore, we investigated an association between sCD163 and the apoptosis marker cytokeratin-18 (CK-18) to explore a link between macrophage activation and apoptosis. METHODS: sCD163 associations with biochemical and histological measures of NAFLD were investigated in two independent cohorts of 157 Australian and 174 Italian NAFLD patients, with liver biopsies graded for NAFLD severity, steatosis and fibrosis. sCD163 and CK-18 were measured by enzyme-linked immunosorbent assay. RESULTS: In both cohorts sCD163 increased in parallel with the patients' morphological disease grading, being independently associated with the Kleiner fibrosis score (P < 0.001). A high sCD163 predicted advanced fibrosis {F ≥ 3; Australian cohort: area under receiver-operating characteristics curve 0.77 [95% confidence interval (CI): 0.76-0.87], Italian cohort: 0.80 (95% CI: 0.72-0.88)}. In both groups, sCD163 was independently associated with CK-18 (P < 0.001). CONCLUSION: Soluble CD163 reflecting macrophage activation is associated with morphological features of NAFLD suggesting their involvement in the pathogenesis of NAFLD, NASH and particularly fibrosis. An independent association between sCD163 and cytokeratin-18 suggests that apoptosis may contribute to macrophage activation in NAFLD/NASH.

Core liver homeostatic co-expression networks are preserved but respond to perturbations in an organism- and disease-specific manner.

Findings about chronic complex diseases are difficult to extrapolate from animal models to humans. We reason that organs may have core network modules that are preserved between species and are predictably altered when homeostasis is disrupted. To test this idea, we perturbed hepatic homeostasis in mice by dietary challenge and compared the liver transcriptome with that in human fatty liver disease and liver cancer. Co-expression module preservation analysis pointed to alterations in immune responses and metabolism (core modules) in both human and mouse datasets. The extent of derailment in core modules was predictive of survival in the cancer genome atlas (TCGA) liver cancer dataset. We identified module eigengene quantitative trait loci (module-eQTL) for these predictive co-expression modules, targeting of which may resolve homeostatic perturbations and improve patient outcomes. The framework presented can be used to understand homeostasis at systems levels in pre-clinical models and in humans. A record of this paper's transparent peer review process is included in the supplemental information.

Intra-familial Transmission of Chronic Hepatitis B Infection: A Large Population-Based Cohort Study in Northern Iran.

AIM: The aim of this study was to investigate the intra-familial transmission of chronic hepatitis B (CHB) in Golestan province, that has the highest prevalence of CHB in Iran. METHODS: The Golestan Cohort Study (GCS) is a population-based prospective study of 50045 individuals, 40 years or older, initially set-up to study upper GI cancers in Northern Iran. In 2008, a baseline measurement of hepatitis B surface antigen (HBsAg) on the stored serum of all GCS participants identified 3505 HBsAg+ individuals. In 2011, we assessed HBV serological markers in 2590 initially HBsAg+ individuals and their first-degree relatives including spouses (1454) and children (3934). RESULTS: The median (IQR) age of spouses and children were 52 (12) and 25 (12) years respectively. Out of 5388 family members, 2393 (44.5%) had no HBV markers, indicating susceptibility to infection. Of these, 378 (15.8%) were fully-vaccinated children with no apparent response to primary immunization. HBsAg was positive in 2.2% (n = 33) of spouses and 8.2% (n = 325) of children (overall rate of 6.6%). HBcAb was positive in 761 (52.3%) and 914 (23%) spouses and children, respectively. The rate of spontaneous loss of HBsAg (HBsAg-, HBsAb+ and HbcAb+) was 41.3% and 13.9% in spouses and children, respectively. A higher rate of HBsAg+ children (10.2%) was found in families in which the mother was positive for HBsAg compared with families where the father was positive for HBsAg (6.3%) (P < 0.001). When both parents were positive for HBsAg, the rate of HBsAg positivity was high (23.5%, P < 0.001). Despite high virus exposure rates between spouses (52.6 %), the prevalence of HBsAg positivity among them was very low (2.3 %). CONCLUSION: Sexual and parent-to-child transmission are important routes of CHB spread in this population from northern Iran despite the fact that 24 years have passed since the beginning of hepatitis B vaccination in infants. Low percentage of HBsAg positivity in spouses is related to high HBsAg clearance rate among them.

Ltb4r1 inhibitor: A pivotal insulin sensitizer?

The potent chemokine leukotriene B4 (LTB4) is increased in obesity, and is associated with insulin resistance. A recent article shows that inhibition of its receptor LTB4 receptor 1 (Ltb4r1) improves insulin sensitivity in muscle and liver via cytokine-independent mechanisms, and reduces proinflammatory immune cell infiltration in the adipose tissue.

Adiponectin attenuates liver fibrosis by inducing nitric oxide production of hepatic stellate cells.

UNLABELLED: Adiponectin protects against liver fibrosis, but the mechanisms have not been fully elucidated. Here, we showed that adiponectin upregulated inducible nitric oxide synthase (iNOS) messenger RNA (mRNA) and protein expression in hepatic non-parenchymal cells, particularly in hepatic stellate cells (HSCs), and increased nitric oxide (NO2-/NO3-) concentration in HSC-conditioned medium. Adiponectin attenuated HSC proliferation and migration but promoted apoptosis in a NO-dependent manner. More advanced liver fibrosis with decreased iNOS/NO levels was observed in adiponectin knockout mice comparing to wide-type mice when administered with CCI4 while NO donor supplementation rescued the phenotype. Further experiments demonstrated that adiponectin-induced iNOS/NO system activation is mediated through adipoR2-AMPK-JNK/Erk1/2-NF-κB signaling. These data suggest that adiponectin inhibits HSC function, further limiting the development of liver fibrosis at least in part through adiponectin-induced NO release. Therefore, adiponectin-mediated NO signaling may be a novel target for the treatment of liver fibrosis. KEY MESSAGES: • Adiponectin activates HSC iNOS/NO and SEC eNOS/NO systems. • Adiponectin inhibits HSC proliferation and migration but promotes its apoptosis. • Adiponectin inhibits CCL4-induced liver fibrosis by modulation of liver iNOS/NO. • Adiponectin stimulates HSC iNOS/NO via adipoR2-AMPK-JNK/ErK1/2-NF-κB pathway.

The multifaceted and controversial immunometabolic actions of adiponectin.

Adiponectin, one of the most abundant adipose-derived hormones, has variable actions in many tissues and organs. Although principally known for its insulin-sensitizing activity, recent data also highlight its homeostatic function, which is mediated both by direct actions on metabolic cells and indirectly through immunomodulatory effects on immune cells. Here we review the multifaceted immunometabolic actions of adiponectin and attempt to unify some of the contradictory reports on adiponectin function in inflammatory processes. We propose that a holistic understanding of adiponectin function can be garnered only from understanding its actions both on the immune system and on metabolism.

Cohort profile: golestan hepatitis B cohort study- a prospective long term study in northern iran ​.

Hepatitis B virus (HBV) infection is the most common cause of end stage liver disease in Iran and in Golestan province. Large-scale population-based prospective cohort studies with long term follow-up are the method of choice to accurately understand the natural course of HBV infection. To date, several studies of HBV epidemiology, natural history, progression to cirrhosis and association with HCC have been reported from other countries. However, few of these are prospective and fewer still are population-based. Moreover, the underlying molecular mechanisms and immunogenetic determinants of the outcome of HBV infection especially in low and middle income countries remains largely unknown. Therefore, the hepatitis B cohort study (HBCS), nested as part of the Golestan Cohort Study (GCS), Golestan, Iran was established in 2008 with the objective to prospectively investigate the natural course of chronic hepatitis B with reference to its epidemiology, viral/host genetic interactions, clinical features and outcome in the Middle East where genotype D HBV accounts for >90% of infections. In 2008, a baseline measurement of HBV surface antigen (HBsAg) was performed on stored serum samples of all GCS participants. A sub-cohort of 3,505 individuals were found to be HBsAg positive and were enrolled in the Golestan HBCS. In 2011, all first degree relatives of HBsAg positive subjects including their children and spouses were invited for HBV serology screening and those who were positive for HBsAg were also included in the Golestan HBCS.

Gender differences in healthy ranges for serum alanine aminotransferase levels in adolescence.

BACKGROUND & AIMS: There is a worldwide epidemic of obesity among adolescents who subsequently are at increased risk for the development of non alcoholic fatty liver disease (NAFLD). The serum alanine aminotransferase (ALT) is the most frequently used test for screening these individuals, but no age and gender-specific upper limits of normal (ULN) based on healthy population data in children are available. The objective of the present study was to define ULN for ALT in healthy children in order to use this as a tool for case finding. METHODS: A total of 975 school children (aged 7-18 years) were included in the study cohort. Highly significant correlations (all p<0.001) were noted between ALT values and measures of BMI, systolic and diastolic blood pressure, insulin levels, HOMA-IR, total cholesterol and triglyceride concentrations. In order to define the population with no risk factors, we excluded subjects having abnormal values for factors that correlated with ALT. This population comprised 186 boys and 185 girls. RESULTS: In boys, median serum ALT levels were 16 IU/L and 9, 11, 18, and 30 IU/L for the 5th, 25th, 75th, and 95th percentiles. In girls, median serum ALT was 13, and 7, 9, 16, and 21 IU/L for the 5th, 25th, 75th, and 95th percentiles, respectively. The ULNs for ALT were 30 IU/L and 21 IU/L for boys and girls respectively. We found a linear relationship between age and ALT in females (p<0.001) but not in males. By multiple logistic regression, independent predictors of an elevated ALT included the BMI, waist hip ratio and levels of serum total cholesterol. In females, age was an additional inverse predictor. CONCLUSIONS: In children and adolescents, these normal limits for ALT should be applied. Those with persistent elevations should be investigated further.

The impact of illicit drug use on spontaneous hepatitis C clearance: experience from a large cohort population study.

BACKGROUND AND AIMS: Acute hepatitis C infection usually ends in chronic infection, while in a minority of patients it is spontaneously cleared. The current population-based study is performed on a large cohort in Golestan province of Iran to examine the demographic correlates of Spontaneous Hepatitis C Clearance. METHODS: Serum samples used in this study had been stored in biorepository of Golestan Cohort Study. These samples were evaluated for anti hepatitis C Virus by third generation Enzyme-linked immunosorbent assay (ELISA). Subjects who tested positive were then invited and tested by Recombinant Immunoblot Assay (RIBA) and Ribonucleic Acid Polymerase Chain Reaction test (PCR). If tested positive for RIBA, subjects were recalled and the two tests were re-done after 6 months. Those subjects who again tested positive for RIBA but negative for PCR were marked as cases of spontaneous clearance. RESULTS: 49,338 serum samples were evaluated. The prevalence of Chronic Hepatitis C Virus (CHCV) infection based on PCR results was 0.31%. Among those who had acquired hepatitis C, the rate of SC was 38%. In multivariate analysis, illicit drug use both Injecting Use (OR = 3.271, 95% CI: 1.784-6.000, p-value<0.001) and Non-Injecting Use (OR = 1.901, 95% CI: 1.068-3.386, p-value = 0.029) were significant correlates of CHCV infection versus SC. CONCLUSIONS: Illicit drug use whether intravenous or non-intravenous is the only significant correlate of CHCV, for which several underlying mechanisms can be postulated including repeated contacts with hepatitis C antigen.

Seroprevalence of hepatitis C virus: the first population-based study from Iran.

OBJECTIVE: Early studies on blood donors point to a seroprevalence of approximately 0.25% for hepatitis C virus (HCV) infection in Iran. However, the true prevalence in the general population is unknown. The objective of this study was to determine the prevalence of HCV infection in the general population of Iran. METHODS: We randomly selected 6583 subjects from three provinces in Iran for inclusion in the study. Subjects were aged between 18 and 65 years. Anti-hepatitis C antibody was tested by a third-generation ELISA test. A recombinant immunoblot assay (RIBA) test was used to confirm the results. Risk factors were recorded and a multivariate analysis was performed. RESULTS: A total of 5684 plasma samples were tested. After confirmatory tests, we found 50 cases of HCV. The overall weighted prevalence of anti-HCV was 0.5%. The rate was significantly higher in men (1.0%) than in women (0.1%). In multivariate analysis, male sex, history of intravenous drug abuse, and imprisonment were significantly associated with anti-HCV. CONCLUSIONS: We found the prevalence of HCV infection in Iran to be higher than previous estimates. It appears that the rate is rising, and in the future, hepatitis C will replace hepatitis B as the most common cause of chronic viral liver disease in Iran.