JOP. J Pancreas (Online) 2009 Mar 9; 10(2):130-142. JOP. Journal of the Pancreas - http://www.joplink.net - Vol. 10, No. 2 - March 2009. [ISSN 1590-8577] 130 ORIGINAL ARTICLE The Proteome of Mesenteric Lymph During Acute Pancreatitis and Implications for Treatment Anubhav Mittal 1 , Anthony RJ Phillips 1,2,3 , Martin Middleditch 2,3 , Katya Ruggiero 2 , Benjamin Loveday 1 , Brett Delahunt 4 , Garth JS Cooper 2,3 , John A Windsor 1,2 1 Department of Surgery, Faculty of Medicine and Health Sciences; 2 School of Biological Sciences; 3 Maurice Wilkins Centre for Molecular Biodiscovery; University of Auckland. Auckland, New Zealand. 4 Department of Pathology and Molecular Medicine, Wellington School of Medicine, University of Otago. Otago, New Zealand ABSTRACT Context The protein fraction of mesenteric lymph during acute pancreatitis and other critical illness is thought to contain toxic factors. However, we do not have a complete description of the mesenteric lymph proteome during acute pancreatitis. Objective The aim of this study was to define the proteomic changes in mesenteric lymph during acute pancreatitis. Setting Animal Laboratory, University of Auckland, New Zealand. Design Mesenteric lymph was collected from sixteen male Wistar rats randomised to Group 1 (n=8) with taurocholate induced acute pancreatitis and Group 2 (n=8) sham control. The lymph was subjected to proteomic analysis using iTRAQ TM (Applied Biosystems, Foster City, CA, USA) and liquid chromatography-tandem mass spectrometry. Results Two hundred and forty-five proteins including 35 hypothetical proteins were identified in mesenteric lymph. Eight of the 245 proteins had a significant increase in their relative abundance in acute pancreatitis conditioned mesenteric lymph, and 7 of these were pancreatic catabolic enzymes (pancreatic amylase 2, pancreatic lipase, carboxypeptidase A2, chymotrypsinogen B, carboxypeptidase B1, cationic trypsinogen, ribonuclease 1). Conclusions This is the first comprehensive description of the proteome of mesenteric lymph during acute pancreatitis and has demonstrated a significantly increased relative abundance of 7 secreted pancreatic catabolic enzymes in acute pancreatitis conditioned mesenteric lymph. This study provides a clear rationale for further research to investigate the efficacy of enteral protease inhibitors in the treatment of acute pancreatitis. INTRODUCTION Acute pancreatitis is a common inflammatory disease that remains a significant clinical challenge. For the third of patients who develop severe acute pancreatitis, the risk of mortality remains high at 20-30% [1, 2] despite improvements in resuscitation and intensive care support [3, 4]. The mortality is due to multiple organ failure, and this has a bimodal time course distribution. Early deaths, during the first week, are due to a fulminant cytokine mediated systemic inflam- matory response syndrome and multiple organ dysfunction (MODS), without an overt septic focus [5]. Later deaths, after 2 or more weeks, are due to MODS associated with infection of necrotic pancreas [6]. Many pathophysiological processes in acute pancreatitis have been described, but the critical factors that drive the MODS have yet to be fully elucidated [1]. There is a body of experimental work, largely derived from rodent studies, suggesting that mesenteric lymph, collected during critical illness, contains toxic factors [7, 8, 9, 10, 11] that contribute to the development of MODS and might be more important than translocated bacteria [12, 13]. Disease conditioned mesenteric lymph is reported to be toxic and associated with neutrophil dysfunction [14, 15], bone marrow suppression [16], and damage to pulmonary epithelial and endothelial cells [17, 18]. Indeed, Magnotti et al. reported that it was disease conditioned mesenteric lymph and not portal venous blood that caused increased endothelial cell permeability and lung injury [19]. This should not be a surprise because the anatomical route of the mesenteric lymph to the subclavian vein via the thoracic duct bypasses the liver. Therefore, unlike portal blood, mesenteric lymph is able to avoid any hepatic first-pass modification or detoxification, and potentially ‘toxic’ factors are instead delivered directly to distant organs (especially Received October 22 nd , 2008 - Accepted December 4 th , 2008 Key words Lymph; Pancreatitis, Acute Necrotizing; Proteomics; Rats Abbreviations IPI: International Protein Index; LC-MS/MS: liquid chromatography-tandem mass spectrometry; MODS: multiple organ dysfunction syndrome; MS: mass spectrometry; NBF: neutral buffered formalin; XO: xanthine oxidase Correspondence John A Windsor Department of Surgery, School of Medicine, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1023, New Zealand Phone: +64-9.373.7599; Fax: +64-9.377.9656 E-mail: j.windsor@auckland.ac.nz Document URL http://www.joplink.net/prev/200903/04.html