The serum protein renalase reduces injury in experimental pancreatitis

Thomas R Kolodecik,Anamika M Reed,Kimie Date,Christine A Shugrue,Vikhil Patel,Shang-Lin Chung,Gary V Desir,Fred S Gorelick

doi:10.1074/jbc.m117.789776

Abstract

Acute pancreatitis is a disease associated with inflammation and tissue damage. One protein that protects against acute injury, including ischemic injury to both the kidney and heart, is renalase, which is secreted into the blood by the kidney and other tissues. However, whether renalase reduces acute injury associated with pancreatitis is unknown. Here, we used both in vitro and in vivo murine models of acute pancreatitis to study renalase's effects on this condition. In isolated pancreatic lobules, pretreatment with recombinant human renalase (rRNLS) blocked zymogen activation caused by cerulein, carbachol, and a bile acid. Renalase also blocked cerulein-induced cell injury and histological changes. In the in vivo cerulein model of pancreatitis, genetic deletion of renalase resulted in more severe disease, and administering rRNLS to cerulein-exposed WT mice after pancreatitis onset was protective. Because pathological increases in acinar cell cytosolic calcium levels are central to the initiation of acute pancreatitis, we also investigated whether rRNLS could function through its binding protein, plasma membrane calcium ATPase 4b (PMCA4b), which excretes calcium from cells. We found that PMCA4b is expressed in both murine and human acinar cells and that a PMCA4b-selective inhibitor worsens pancreatitis-induced injury and blocks the protective effects of rRNLS. These findings suggest that renalase is a protective plasma protein that reduces acinar cell injury through a plasma membrane calcium ATPase. Because exogenous rRNLS reduces the severity of acute pancreatitis, it has potential as a therapeutic agent.

Highlights

Acute pancreatitis is a potentially life-threatening disease that affects more than 250,000 people each year in the United States, making it the leading cause of hospitalization for gastro
A dose of 25 ␮g/ml was used. recombinant RNLS (rRNLS) inhibited carbachol-stimulated trypsinogen (Fig. 1C) and chymotrypsinogen activation (Fig. 1D) and tended to have similar protective effects after bile acid exposure (Fig. 1, E and F). rRNLS significantly reduced cellular injury as measured by MTT conversion, a measure of metabolic function, in CER-treated lobules (Fig. 2A). rRNLS prevented morphologic changes in acinar cells associated with pancreatitis; most notably, the typical acinar cell vacuolization was eliminated (Fig. 2B, compare panel 2 versus panel 4)
We examine whether RNLS, a plasma protein with protective effects in models of acute renal and cardiac injury [11, 12], could decrease injury in murine models of acute pancreatitis and whether it can act directly on the pancreatic acinar cell

Summary

Introduction

Acute pancreatitis is a potentially life-threatening disease that affects more than 250,000 people each year in the United States, making it the leading cause of hospitalization for gastro-. After induction of CER pancreatitis, we found that RNLS deletion did not change either tissue edema (percent wet weight) or serum amylase levels (data not shown). These studies suggest that the protective effects of RNLS on CER-induced acinar cell injury are mediated by a PMCA.

Results

Conclusion