Cholestatic liver diseases such as primary biliary cirrhosis and primary sclerosing cholangitis are often associated with increased serum bile acid concentrations. Previous reports have also indicated a decrease in circulating glucocorticoid levels in these diseases. Glucocorticoid production and secretion are under the direct control of the hypothalamus-pituitary-adrenal (HPA) axis. We have obtained novel preliminary data indicating that there is a dampening of the HPA axis activity in our rodent model of cholestatis liver disease and that this may contribute to the cholangiocyte outgrowth seen in the early stages of cholestasis. The overall objective of this proposal is to determine the consequences of cholestatic liver disease on the brain and more specifically on the HPA axis and in turn determine the subsequent effects of a dampened HPA axis activity have on cholangiocyte proliferation. Based upon strong preliminary data, we propose the novel central hypothesis that the bile acids that accumulate in the serum during cholestasis are responsible for the dampening of the HPA axis and that the subsequent decrease in circulating glucocorticoid levels have implications on cholangiocyte proliferation. Our proposed work will focus on three specific aims that have been designed to test the following working hypotheses: (1) Decreased HPA axis activity is a consequence of cholestasis and contributes to the resulting increased cholangiocyte proliferation, (2) Serum bile acids accumulate in the brain during cholestasis and subsequently suppresses the HPA axis via the specific uptake of bile acids by bile acid transporters into neurons of particular brain regions and subsequent activation of glucocorticoid receptors, and (3) Reactivation of the HPA axis by central administration of corticotropin releasing hormone effectively inhibits the cholangiocyte outgrowth seen during cholestasis via the glucocorticoid receptor- mediated inhibition of AP-1 and NFkB transcriptional activity. Dissecting the pathophysiological interactions between the brain and the liver during cholestatic liver diseases may lead to an enhanced understanding of the pathological processes and consequences of this particular type of live disease. This knowledge may play a paramount role in the development of therapeutic strategies for the treatment of cholangiopathies.
The health relatedness of this application is that effective treatments are lacking for chronic cholestatic live diseases, such as primary biliary cirrhosis and primary sclerosing cholangitis. Cholestatic liver diseases are often associated with an impaired brain function that leads to dysregulated stress hormone control. The rationale for our research is that the successful completion of the studies can ultimately be expected to provide a greater understanding of cholestatic liver disease progression and increase the opportunities for the development of novel treatment paradigms for chronic liver diseases.
|Quinn, Matthew; McMillin, Matthew; Galindo, Cheryl et al. (2014) Bile acids permeabilize the blood brain barrier after bile duct ligation in rats via Rac1-dependent mechanisms. Dig Liver Dis 46:527-34|
|Han, Yuyan; Onori, Paolo; Meng, Fanyin et al. (2014) Prolonged exposure of cholestatic rats to complete dark inhibits biliary hyperplasia and liver fibrosis. Am J Physiol Gastrointest Liver Physiol 307:G894-904|
|McMillin, Matthew; Galindo, Cheryl; Pae, Hae Yong et al. (2014) Gli1 activation and protection against hepatic encephalopathy is suppressed by circulating transforming growth factor ?1 in mice. J Hepatol 61:1260-6|
|McMillin, Matthew; Frampton, Gabriel; Thompson, Michelle et al. (2014) Neuronal CCL2 is upregulated during hepatic encephalopathy and contributes to microglia activation and neurological decline. J Neuroinflammation 11:121|
|Renzi, Anastasia; DeMorrow, Sharon; Onori, Paolo et al. (2013) Modulation of the biliary expression of arylalkylamine N-acetyltransferase alters the autocrine proliferative responses of cholangiocytes in rats. Hepatology 57:1130-41|
|DeMorrow, Sharon; Meng, Fanyin; Venter, Julie et al. (2013) Neuropeptide Y inhibits biliary hyperplasia of cholestatic rats by paracrine and autocrine mechanisms. Am J Physiol Gastrointest Liver Physiol 305:G250-7|
|Francis, Heather L; Demorrow, Sharon; Franchitto, Antonio et al. (2012) Histamine stimulates the proliferation of small and large cholangiocytes by activation of both IP3/Ca2+ and cAMP-dependent signaling mechanisms. Lab Invest 92:282-94|
|Meng, Fanyin; Francis, Heather; Glaser, Shannon et al. (2012) Role of stem cell factor and granulocyte colony-stimulating factor in remodeling during liver regeneration. Hepatology 55:209-21|
|Quinn, Matthew; Ueno, Yoshiyuki; Pae, Hae Yong et al. (2012) Suppression of the HPA axis during extrahepatic biliary obstruction induces cholangiocyte proliferation in the rat. Am J Physiol Gastrointest Liver Physiol 302:G182-93|
|Renzi, Anastasia; Glaser, Shannon; Demorrow, Sharon et al. (2011) Melatonin inhibits cholangiocyte hyperplasia in cholestatic rats by interaction with MT1 but not MT2 melatonin receptors. Am J Physiol Gastrointest Liver Physiol 301:G634-43|