Collagen Characterization in a Model of Nonalcoholic Steatohepatitis with Fibrosis; A Call for Development of Targeted Therapeutics.

Left untreated, nonalcoholic fatty liver disease can progress to nonalcoholic steatohepatitis (NASH), fibrosis, and end-stage liver disease. To date, few if any therapies have proven effective against NASH with fibrosis. Quantification and qualification of hepatic scar might enable development of more effective targeted therapies. In a murine model of NASH induced by diet, we characterized fibrillar collagen deposition within the hepatic parenchyma. At harvest, livers from the modified diet cohort exhibited NASH with fibrosis. Transcriptomic analysis of hepatic tissue revealed increased col1a1, col1a2, and col3a1, each of which correlated directly with hepatic hydroxyproline content. Circular polarized microscopic analysis of Picrosirius red-stained liver sections revealed deposition of collagen type I within the parenchyma. Development of therapeutics designed to mitigate collagen type I accumulation might prove effective in NASH with fibrosis.

Identification of disease-associated microRNA in a diet-induced model of nonalcoholic steatohepatitis.

Emerging evidence suggests that microRNA dysregulation plays an important role in nonalcoholic steatohepatitis. Using a model of diet-induced liver disease that progresses to fibrosis and hepatocellular carcinoma, we identify a set of 22 microRNA with robust correlation with liver enzyme levels and liver collagen content. These disease-asssociated miRs play pivotal roles in steatosis, extracellular matrix deposition and liver cancer, and may form the basis for identification of therapeutic strategies against this form of liver disease.

Collagen-driven remodeling of the intrahepatic duct wall in the PCK rat model of polycystic kidney disease-Caroli syndrome.

AIM OF THE STUDY: Autosomal dominant polycystic kidney disease (ADPKD) is characterized by formation and expansion of cysts within the kidney. Caroli syndrome (CS) is characterized by cystic saccular dilatation of intrahepatic ducts. Kidney and liver images from a model of ADPKD-CS were evaluated to characterize remodeling of the cystically dilated intrahepatic duct wall and the renal cyst wall. MATERIAL AND METHODS: Archival digitized images from Masson's trichrome-stained renal and Picrosirius red (PSR)-stained renal and hepatic cross-sections were sourced from the PCK rat model of ADPKD-CS, and age-matched Sprague-Dawley rats (wild-type). Cross-sectional areas and wall thicknesses of renal cysts and intrahepatic ducts were measured. Circularly polarized PSR microscopy was utilized to observe accumulation of collagen and identify its subtype. RESULTS: In the PCK rat model of ADPKD-CS, renal cysts were relatively thin-walled in comparison to intrahepatic ducts with renal cyst cross-sectional area to wall ratio 47-fold greater than the corresponding ratio in intrahepatic ducts. Increasing intrahepatic duct cross-sectional area was accompanied by a rapid and steep rise in wall thickness. There was a weak but significant direct correlation (r = 0.49, p = 0.037) between renal cyst cross-sectional area and wall thickness. Circularly polarized Picrosirius red microscopy revealed collagen I accumulation within the walls of dilated intrahepatic ducts but not renal cysts. CONCLUSIONS: These data suggest that unlike renal cysts, cystically dilated intrahepatic ducts undergo collagen-driven wall remodeling in the PCK rat.

Glycerol-3-phosphate Acyltransferase1 Is a Model-Agnostic Node in Nonalcoholic Fatty Liver Disease: Implications for Drug Development and Precision Medicine.

Left untreated nonalcoholic fatty liver disease (NAFLD) can progress to nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. The observed failure of clinical trials in NASH may suggest that current model systems do not fully recapitulate human disease, and/or hallmark pathological features of NASH may not be driven by the same pathway in every animal model let alone in each patient. Identification of a model-agnostic disease-associated node can spur the development of effective drugs for the treatment of liver disease. Glycerol-3-phosphate acyltransferase1 (GPAT1) plays a pivotal role in lipid accumulation by shunting fats away from oxidation. In the present study, hepatic GPAT1 expression was evaluated in three etiologically different models of NAFLD. Compared to the sham cohort, hepatic GPAT1 mRNA levels were elevated by ∼5-fold in steatosis and NASH with fibrosis with immunofluorescent staining revealing increased GPAT1 in the fatty liver. A significant and direct correlation (r = 0.88) was observed between hepatic GPAT1 mRNA expression and severity of the liver disease. Picrosirius red staining revealed a logarithmic relation between hepatic GPAT1 mRNA expression and scar. These data suggest that hepatic GPAT1 is an early disease-associated model-agnostic node in NAFLD and form the basis for the development of a potentially successful therapeutic against NASH.

Liver Biopsy Hydroxyproline Content Is a Diagnostic for Hepatocellular Carcinoma in Murine Models of Nonalcoholic Steatohepatitis.

There is increasing evidence that nonalcoholic steatohepatitis (NASH) is a risk factor for hepatocellular carcinoma (HCC) in the absence of cirrhosis, a phenomenon termed noncirrhotic HCC. Early diagnosis of HCC is critical to a favorable prognosis. We tested the hypothesis that hydroxyproline content of liver biopsy samples is diagnostic for HCC in murine models of NASH induced by diet or by diet and chemicals. The training set comprised mice fed a standard diet or a fast-food diet with or without administration of thioacetamide. At harvest, livers from the modified diet cohort exhibited NASH with a subset of NASH livers exhibiting HCC. Hydroxyproline content was measured in liver biopsy samples with tissue in the NASH+HCC cohort sampled from the remote, nontumor parenchyma. Plotting the receiver operating characteristics (ROC) with hydroxyproline as the continuous variable against the absence or presence of HCC yielded an area under ROC of 0.87, a threshold of >0.18 µg hydroxyproline/mg liver and sensitivity of 91% with a specificity of 83.3%. The use of liver hydroxyproline content as a diagnostic for HCC in a test set comprising healthy, NASH and NASH+HCC livers proved 87% accurate.