ENOblock attenuates intestinal ischemia/reperfusion-induced acute lung injury and improves survival

Intestinal ischemia/reperfusion triggers systemic inflammatory responses that contribute to acute lung injury. Enolase-1 is a glycolytic enzyme increasingly implicated in its proinflammatory functions and in tissue injury. We hypothesized that an Enolase-1 inhibitor, ENOblock treatment would attenuate acute lung injury and improve survival following intestinal ischemia/reperfusion.

Adult C57BL/6 mice were subjected to superior mesenteric artery occlusion for 1 hour followed by 4 hours of reperfusion. Mice received either vehicle or ENOblock (5 mg/kg body weight) via retro-orbital injection at reperfusion. Mice were harvested for blood, intestines, and lungs after 4 hours of reperfusion or euthanized at 36 hours for survival. Enolase-1 messenger RNA was measured by quantitative polymerase chain reaction, and enolase-1 protein was measured by Western blotting. Plasma cytokines and injury markers were quantified with enzyme-linked immunosorbent assay or colorimetric assays. Lung tissues were analyzed by quantitative polymerase chain reaction, histology, and terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling assays. Neutrophil infiltration was assessed by myeloperoxidase activity.

Intestinal ischemia/reperfusion significantly increased lung enolase-1 messenger RNA and protein expression. ENOblock attenuated intestinal injury and reduced epithelial cell death. ENOblock treatment also significantly reduced circulating inflammatory and injury markers, as evidenced by the decreased plasma levels of interleukin-6, lactate dehydrogenase, and alanine aminotransferase. In the lungs, ENOblock significantly reduced intestinal ischemia/reperfusion-induced messenger RNA expression of interleukin-6, keratinocyte-derived chemokine, and macrophage inflammatory protein-2, and decreased pulmonary myeloperoxidase activity. Histology showed reduced alveolar injury and decreased pulmonary terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling-positive cells in ENOblock-treated mice. ENOblock was found to improve survival after intestinal ischemia/reperfusion.

Enolase-1 is upregulated in the lungs following intestinal ischemia/reperfusion. ENOblock administered at reperfusion attenuates intestinal and lung injury and improves survival, supporting it as a potential therapeutic strategy for mitigating ischemia/reperfusion-induced acute lung injury and mortality.