Glycemic Control Predicts Severity of Hepatocyte Ballooning and Hepatic Fibrosis in Nonalcoholic Fatty Liver Disease.

BACKGROUND AND AIMS: Whether glycemic control, as opposed to diabetes status, is associated with the severity of NAFLD is open for study. We aimed to evaluate whether degree of glycemic control in the years preceding liver biopsy predicts the histological severity of NASH. APPROACH AND RESULTS: Using the Duke NAFLD Clinical Database, we examined patients with biopsy-proven NAFLD/NASH (n = 713) and the association of liver injury with glycemic control as measured by hemoglobin A1c (HbA1c). The study cohort was predominantly female (59%) and White (84%) with median (interquartile range) age of 50 (42, 58) years; 49% had diabetes (n = 348). Generalized linear regression models adjusted for age, sex, race, diabetes, body mass index, and hyperlipidemia were used to assess the association between mean HbA1c over the year preceding liver biopsy and severity of histological features of NAFLD/NASH. Histological features were graded and staged according to the NASH Clinical Research Network system. Group-based trajectory analysis was used to examine patients with at least three HbA1c (n = 298) measures over 5 years preceding clinically indicated liver biopsy. Higher mean HbA1c was associated with higher grade of steatosis and ballooned hepatocytes, but not lobular inflammation. Every 1% increase in mean HbA1c was associated with 15% higher odds of increased fibrosis stage (OR, 1.15; 95% CI, 1.01, 1.31). As compared with good glycemic control, moderate control was significantly associated with increased severity of ballooned hepatocytes (OR, 1.74; 95% CI, 1.01, 3.01; P = 0.048) and hepatic fibrosis (HF; OR, 4.59; 95% CI, 2.33, 9.06; P < 0.01). CONCLUSIONS: Glycemic control predicts severity of ballooned hepatocytes and HF in NAFLD/NASH, and thus optimizing glycemic control may be a means of modifying risk of NASH-related fibrosis progression.

Vitamin D is Not Associated With Severity in NAFLD: Results of a Paired Clinical and Gene Expression Profile Analysis.

OBJECTIVES: The pathogenesis of nonalcoholic fatty liver disease (NAFLD) is complex. Vitamin D (VitD) has been implicated in NAFLD pathogenesis because it has roles in immune modulation, cell differentiation and proliferation, and regulation of inflammation. We evaluated the association of VitD levels, hepatic gene expression for VitD metabolizing genes, and NAFLD histological severity. METHODS: Two adult cohorts, controls (n=39) and NAFLD (n=244), who underwent liver biopsy were compared. Two-sided t-tests or Wilcoxon's rank-sum tests for continuous predictors and chi-squared tests or Fisher's exact tests for categorical variables were used to analyze the association of VitD and NAFLD. Generalized linear models were used to analyze the association of VitD levels and VitD metabolizing genes with histological severity of NAFLD while adjusting for potential confounders and correcting for multiple comparisons. RESULTS: NAFLD patients were more likely than controls to have higher HbA1c (6.5±1.2 vs 5.9±1.0; P=0.009), a risk factor for VitD deficiency. However, no difference in VitD levels was observed between groups. VitD levels did not correlate with the severity of hepatic steatosis, lobular or portal inflammation, or ballooned hepatocytes after adjusting for confounding factors. Furthermore, no association was noted between VitD deficiency or differential expression of genes involved in VitD metabolism and severity of hepatic fibrosis or any other histologic feature of NAFLD. CONCLUSIONS: Neither VitD deficiency, nor hepatic expression of VitD-related genes, associate with the presence or histologic severity of NAFLD in patients. Hence, despite preclinical evidence implicating VitD in NAFLD pathogenesis, VitD deficiency does not appear to be associated with NAFLD severity in humans.

Repair-related activation of hedgehog signaling in stromal cells promotes intrahepatic hypothyroidism.

Thyroid hormone (TH) is important for tissue repair because it regulates cellular differentiation. Intrahepatic TH activity is controlled by both serum TH levels and hepatic deiodinases. TH substrate (T4) is converted into active hormone (T3) by deiodinase 1 (D1) but into inactive hormone (rT3) by deiodinase 3 (D3). Although the relative expressions of D1 and D3 are known to change during liver injury, the cell types and signaling mechanisms involved are unclear. We evaluated the hypothesis that changes in hepatic deiodinases result from repair-related activation of the Hedgehog pathway in stromal cells. We localized deiodinase expression, assessed changes during injury, and determined how targeted manipulation of Hedgehog signaling in stromal cells impacted hepatic deiodinase expression, TH content, and TH action in rodents. Humans with chronic liver disease were also studied. In healthy liver, hepatocytes strongly expressed D1 and stromal cells weakly expressed D3. During injury, hepatocyte expression of D1 decreased, whereas stromal expression of D3 increased, particularly in myofibroblasts. Conditionally disrupting Hedgehog signaling in myofibroblasts normalized deiodinase expression. Repair-related changes in deiodinases were accompanied by reduced hepatic TH content and TH-regulated gene expression. In patients, this was reflected by increased serum rT3. Moreover, the decreases in the free T3 to rT3 and free T4 to rT3 ratios distinguished advanced from mild fibrosis, even in individuals with similar serum levels of TSH and free T4. In conclusion, the Hedgehog-dependent changes in liver stromal cells drive repair-related changes in hepatic deiodinase expression that promote intrahepatic hypothyroidism, thereby limiting exposure to T3, an important factor for cellular differentiation.