Elsevier

Peptides

Volume 26, Issue 12, December 2005, Pages 2491-2499
Peptides

Albumin peptide: A molecular marker for trauma/hemorrhagic-shock in rat mesenteric lymph

https://doi.org/10.1016/j.peptides.2005.05.001Get rights and content

Abstract

Vascular permeability and endothelial cell damage has been shown to occur in rats subjected to trauma with hemorrhagic-shock. Although the factors responsible for the endothelial cell injury are unknown, it has been hypothesized that toxic factors produced in response to hemorrhagic-shock originate in the gut and are absorbed into the mesenteric lymphatics. Consistent with this hypothesis, it has been shown that lymph collected from animals subjected to trauma with hemorrhagic-shock (T/HS) results in a marked decrease in endothelial cell viability both in vitro and in vivo. We therefore compared the lymph collected pre-T/HS to samples collected during, and up to 3 h post-T/HS in order to identify a factor present or increased in post-T/HS lymph. This analysis revealed that a single cationic peptide band was significantly increased in post-T/HS lymph, but not in lymph from control animals subjected to trauma without hemorrhagic-shock (T/SS). This peptide was subsequently identified as the N-terminal 24 amino acids of rat serum albumin (RSA) by mass spectrometry and amino acid sequencing. Although the measured increase in the albumin peptide correlates with detectable shock lymph-induced endothelial cell toxicity, the peptide was not toxic to endothelial cells. We therefore propose that the significant increase in the albumin peptide is a marker for post-T/HS lymph-induced endothelial cell toxicity.

Introduction

It has been recognized for over 25 years that the development of a dysregulated inflammatory response as well as acute lung injury and multiple organ failure (MOF) complicates the recovery of patients with severe trauma [11]. In spite of this recognition, advances in medical care have done little to reduce the incidence or mortality rate of trauma-induced acute lung injury or MOF. This failure of medical therapy appears to be related, at least in part, to an incomplete understanding of the mechanisms by which trauma–hemorrhage leads to acute organ dysfunction. Although the relationship between trauma–hemorrhage and acute pulmonary dysfunction as well as systemic inflammation has been recognized for many years, the pathogenesis of trauma/shock-induced pulmonary microvascular dysfunction is not well understood [11]. Nevertheless, it is clear that hemorrhagic-shock and major trauma are associated with intestinal ischemia and loss of gut barrier function [10], [12], [16], [19], [27]. Experimental animal models have been developed to investigate the events that lead to successive organ failure following trauma with hemorrhagic-shock (T/HS). The data from these experiments lend strong evidence that factors contributing to post-T/HS organ failure originate in the ischemic gut and are introduced systemically via the mesenteric lymphatics [1], [2], [3], [12], [13], [14], [31], [33], [34]. First, these data show that lymph duct ligation prior to shock can abrogate the lung damage, gut permeability, bone marrow (BM) suppression, neutrophil (PMN) activation and endothelial cell damage that is normally seen in these animals after T/HS [3], [33]. Second, the deleterious in vivo effects on BM, PMN and endothelial cells can be recreated in vitro by incubating these cells with post-T/HS lymph but not pre-T/HS or lymph collected from animals subjected to trauma without shock (T/SS). These data therefore indicate that factors responsible for this damage are present in post-T/HS lymph and are produced or increased due to T/HS [2], [13], [22], [23], [34].

Previous studies have excluded translocating bacteria [12], endotoxin [12], cytokines and xanthine oxidase (12, 13) as factors responsible for the biologic activity in post-shock lymph. We have, however, recently reported that a modified form of rat serum albumin (RSA) and multiple lipid factors are implicated in T/HS lymph-induced endothelial cell toxicity [17]. In this study, we have continued our efforts in the identification of factors present in post-T/HS lymph that are responsible for endothelial cell toxicity and report the finding of a novel 24-amino acid peptide that is significantly increased in post-T/HS mesenteric lymph.

Section snippets

Animals

Male Sprague-Dawley rats (pathogen-free, Taconic, Long Island, NY) were housed in barrier-sustained conditions under 12 h light/12 h dark cycles, and allowed free access to water and chow (Teklad 22/5 rodent diet W-8640, Harlan Teklad, Madison, WI). Rat maintenance was performed in accordance with the “Guide for the Care and Use of Laboratory Animals” and all procedures were approved by the New Jersey Medical School Animal Care Committee.

Trauma/hemorrhagic-shock model and lymph collection

Mesenteric lymph was collected from male rats (300–350 g)

Analysis of lymph

Lymph collected from animals following trauma with hemorrhagic-shock has been shown to be toxic to endothelial cells, whereas the lymph collected prior to shock or from animals subjected to trauma without shock is not [13], [23]. We therefore hypothesized that T/HS results in the production or increase of a factor(s) in mesenteric lymph that is toxic to endothelial cells. To test this hypothesis, pre-T/HS lymph was compared to lymph collected during and up to 3 h post-T/HS in order to identify

Discussion

Endothelial cell injury, bone marrow suppression, neutrophil activation and increased red blood cell rigidity are in vivo systemic effects that have been observed in studies of rats subjected to trauma with hemorrhagic-shock [1], [2], [3], [23], [33]. Although the factors responsible for these effects are unknown, experimental data suggest they are produced by the gut and transported to the general circulation through the mesenteric lymphatics. Since the endothelium plays a central role in

Acknowledgements

The authors thank Dr. G. Diamond for critical reading of the manuscript, J. Kaiser for editing, Dr. A. Haag and R. Jones for technical assistance. This study was supported by National Institutes of Health Grant GM59841 (to EAD).

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