A Novel ELR-CXC Chemokine Antagonist Reduces Intestinal Ischemia Reperfusion-Induced Mortality, and Local and Remote Organ Injury

Abstract

Neutrophil sequestration plays an important role in mediating local and remote organ injury induced by ischemia and reperfusion (I/R). The Glu-Leu-Arg (ELR)-CXC subfamily of chemokines, all CXCR1 or CXCR2 ligands, are primary agonists for such neutrophil recruitment. Herein, we assessed the effects of a combined CXCR1/CXCR2 antagonist, CXCL8((3-72))K11R/G31P (G31P), on neutrophilic local (gut) and distant organ injury and outcomes after superior mesenteric artery I/R in rats. Male Sprague-Dawley rats (n=6-10) were subjected to either sham treatment or superior mesenteric artery ischemia for 1h; all animals received either saline or G31P (500 mug/kg, s.c.) and were euthanized for assessment after either 2 or 5h of arterial reperfusion. Survival and gut pathology, and pulmonary neutrophils were assessed directly, while bronchoalveolar lavage (BAL) fluid total protein levels and red blood cell (RBC) numbers were determined by protein assay and direct counting. Expression of inflammatory mediators in the lung and jejunum was measured by quantitative RT-PCR, colorimetric or gel zymography assays. Sham treatment animals suffered no discernible gut or pulmonary pathology. At 2 and 5h after reperfusion, the survival levels of the saline-treated I/R injury animals were 80% and 50%, respectively, while all G31P-treated animals survived. I/R injury led to substantial villous pathology within the jejunum, and G31P significantly reduced these pathology scores as well as neutrophil infiltration of the jejunal lamina propria and lung parenchyma, and vascular leakage into the airways (BAL protein). The tissue injury increased expression of myeloperoxidase and matrix metalloproteinase (MMP)-2 and MMP-9 in the gut tissues, but G31P treatment did not significantly affect this response. Intestinal I/R increased expression of IL-1, IL-6, GRO, and MIP-2 in the ischemic jejunum and the lung tissues, but here too G31P treatment had no palliative effects on these responses. These results suggest that full-spectrum ELR-CXC chemokine antagonism has significant protective effects against I/R-induced local and remote organ injury.