Pancreatic trophism in experimental liver cirrhosis

Decreased expression of insulin and increased expression of pancreatic transcription factor PDX-1 in islets in patients with liver cirrhosis: a comparative investigation using human autopsy specimens

BACKGROUND

Glucose intolerance in patients with liver cirrhosis (LC), known as hepatogenous diabetes, is thought to be distinct from type 2 diabetes (T2DM) in some aspects. Hyperinsulinemia and/or insulin resistance in liver disease is associated with hepatocarcinogenesis, growth of hepatocellular carcinoma, and poor prognosis. However, the pathophysiological processes in islets that are responsible for hyperinsulinemia in LC are still not precisely known. Therefore, we investigated the histopathological differences in islets of Langerhans cells between LC and T2DM.

METHODS

A total of 35 human autopsy pancreatic tissue samples were used in this study (control, n = 18; T2DM, n = 6; LC, n = 11). The expression of insulin, glucagon, somatostatin, pancreatic duodenal homeobox-1 (PDX-1), proliferating cell nuclear antigen (PCNA), and Ki-67 was examined using immunohistochemistry and quantitated by image analysis.

RESULTS

Islet hypertrophy and a significant increase in PCNA-positive cells in islets were observed in the tissues from LC cases. The insulin-positive areas in islets were significantly decreased in LC cases compared with control and T2DM cases (P = 0.001, P = 0.035, respectively), whereas the PDX-1-positive area was significantly increased in LC cases (P = 0.001) compared with the control. Furthermore, disorganization of pancreatic endocrine cells and nucleocytoplasmic translocation of PDX-1 were both seen in the LC subjects.

CONCLUSIONS

In LC, islets undergo hypertrophy and exhibit paradoxical expression of insulin and PDX-1. In the subjects autopsied, insulin expression was decreased, whereas expression of the pancreatic transcription factor PDX-1 was increased in LC. These results point to important distinctions between LC and T2DM.

Insulin resistance and chronic liver disease

Increased insulin resistance is frequently associated with chronic liver disease and is a pathophysiological feature of hepatogenous diabetes. Distinctive factors including hepatic parenchymal cell damage, portal-systemic shunting and hepatitis C virus are responsible for the development of hepatogenous insulin resistance/diabetes. Although it remains unclear whether insulin secretion from pancreatic beta cells is impaired as it is in type 2 diabetes, retinopathic and cardiovascular risk is low and major causes of death in cirrhotic patients with diabetes are liver failure, hepatocellular carcinoma and gastrointestinal hemorrhage. Hemoglobin A1c is an inaccurate marker for the assessment and management of hepatogenous diabetes. Moreover, exogenous insulin or sulfonylureas may be harmful because these agents may promote hepatocarcinogenesis. Thus, pathogenesis, cause of death, assessment and therapeutic strategy for hepatogenous insulin resistance/diabetes differ from those for lifestyle-related type 2 diabetes. In this article, we review features of insulin resistance in relationship to chronic liver disease. We also discuss the impact of anti-diabetic agents on interferon treatment and hepatocarcinogenesis.

Impaired pancreatic exocrine function in rats with carbon tetrachloride-induced liver cirrhosis

BACKGROUND

Substantial numbers of studies have revealed the close correlation between chronic pancreatitis and cirrhosis in human. However, the situation with regard to pancreatic enzyme secretion is less clear.

AIM

The aim of the study was to investigate pancreatic exocrine function in rats with carbon tetrachloride-induced liver cirrhosis in rats.

METHODS

Pancreatic exocrine function and morphology in Sprague-Dawley rats with carbon tetrachloride-induced liver cirrhosis were investigated. Pancreatic exocrine functions stimulated by cholecystokinin-8 and other secretagogs were assessed in isolated pancreatic acini, and in vivo and morphological changes were studied by routine histological examination and electron microscopy.

RESULTS

The basal and cholecystokinin-8-stimulated amylase releases from acini and acinar amylase content were significantly lower in the cirrhotic rats than the control. None of the secretagogs induced the some amount of amylase release in cirrhotic as in control rats. Volume of the pancreatic juice and outputs of amylase and protein were significantly decreased under basal and cholecystokinin-8-stimulated conditions in vivo. Electron microscopy revealed most of the rough-surfaced endoplasmic reticulum accompanying less numbers of ribosomes to be dilated and some mitochondria to be swollen in cirrhotic rats.

CONCLUSION

Pancreatic exocrine functions are decreased in cirrhotic rats owing to alterations at the electron microscopic levels, reflecting an impaired acinar intracellular messenger system.