Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCB118

Poster Communications

Application of ethanol with fatty acids induces Ca2+ responses in pancreatic stellate cells in vitro and leads to activation of these cells in vivo

P. E. Ferdek1, M. A. Jakubowska2, X. Zhang3, W. Huang4,5, R. Sutton3, O. H. Petersen6

1. Department of Cell Biology, Faculty of Biochemistry, Biophysics and Biotechnolgy, Jagiellonian University, Krakow, Poland. 2. Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland. 3. Liverpool Pancreatitis Study Group, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom. 4. Department of Integrated Traditional Chinese and Western Medicine, Sichuan Provincial Pancreatitis Centre, West China Hospital, Sichuan University, Chengdu, China. 5. West China-Liverpool Biomedical Research Centre, West China Hospital, Sichuan University, Chengdu, China. 6. Medical Research Council Group, School of Biosciences, Cardiff University, Cardiff, United Kingdom.

Pancreatic fibrosis, a frequent complication of alcoholic pancreatitis, is a result of an excessive activation of pancreatic stellate cells (PSCs), which assume a myofibroblast-like phenotype and deposit collagen fibres in the tissue. The products of non-oxidative alcohol metabolism, fatty acid ethyl esters formed by ethanol and fatty acids, have long been known to cause pancreatic acinar cell (PAC) injury via induction of excessive Ca2+ responses, leading to premature intracellular activation of digestive enzymes (1). Although it has been suggested that ethanol may contribute to PSC activation (2), the exact mechanism of pathology induced by ethanol and its metabolites has not yet been elucidated in PSCs. Recently it has become clear that PACs and PSCs, despite their very close proximity in the tissue, respond differently, in terms of Ca2+ signals, to physiological and pathophysiological stimuli (3). Therefore it becomes essential to examine the effects caused by ethanol metabolites in PSCs and understand their role in PSC activation and the development of pancreatic fibrosis. To achieve this, the effects of acute administration of ethanol and palmitoleic acid (POA) on intracellular Ca2+ were investigated in human PSCs. Also, the expression of fibrotic markers in PSCs was examined in vivo in a recently established mouse model of alcoholic acute pancreatitis and compared to models of bile-induced pancreatitis (procedures performed in accordance with UK Home Office regulations). POA/ethanol (10µM/10mM to 200µM/200mM) induced global and sustained cytosolic Ca2+ rises in PSCs. Complete removal of extracellular Ca2+ reduced but did not abolish the POA/ethanol-induced Ca2+ elevation in PSCs, indicating that the initial Ca2+ release from the ER triggers further Ca2+ influx to the cytosol from the extracellular environment. After the ER store was depleted with cyclopiazonic acid (CPA), POA/ethanol failed to trigger Ca2+ responses in PSCs. Further, POA and ethanol induced acute pancreatitis in vivo, which was characterised by mild to moderate pancreatic oedema, necrosis, immune cell infiltration and activity of myeloperoxidase. Importantly POA/etanol increased the expression of α-SMA in between pancreatic acini, which has been attributed to the increased activation of PSCs. In the model of alcoholic pancreatitis the α-SMA expressing cells were uniformly distributed across the entire tissue, whereas in two models of bile-induced pancreatitis elevated expression of α-SMA was limited only to the necrotic areas. Our study sheds new light on the current understanding of mechanisms underlying alcohol metabolite-induced pancreatic pathology, which involves not only signalling in PACs but also in PSCs, likely leading to their activation in vivo. Our results also suggest that despite a relatively mild severity, in alcoholic pancreatitis PSCs become activated uniformly throughout the pancreas, possibly even to a greater extent compared to bile-induced pancreatitis.

Where applicable, experiments conform with Society ethical requirements