Estradiol mediates the long-lasting lung inflammation induced by intestinal ischemia and reperfusion

Abstract

Background: Lung inflammation is one of the main consequences of intestinal ischemia reperfusion (intestinal IR) and, in severe cases, can lead to acute respiratory distress syndrome and death. We have previously demonstrated that estradiol exerts a protective effect on lung edema and cytokine release caused by intestinal IR in male rats.

Materials and methods: We investigated the role of estradiol on the generation of interleukin (IL)-1β, IL-10, vascular endothelial growth factor (VEGF), and cytokine-induced neutrophil chemoattractant 1 (CINC-1) in a female rat model of intestinal IR. Blood and bone marrow leukocytes were also quantified. Seven-days-ovariectomized rats were subjected to intestinal IR by occlusion of the superior mesenteric artery for 45 min. After reperfusion of the tissue for 2 h, the rats were sacrificed. Lung tissue was collected, cultured for 24 h and assayed.

Results: We observed a significant increase in serum levels of IL-10, CINC-1, uric acid and circulating, but not bone marrow, leukocyte numbers. In addition, intestinal IR induced a significant increase in the ex-vivo lung levels of IL-1β, IL-10, and VEGF. Treatment with 17β-estradiol before the induction of intestinal IR prevented the systemic release of IL-10, CINC-1, and uric acid, but it did not affect the leukocytosis. In addition, 17β-estradiol significantly prevented the ex-vivo release of IL-1β and VEGF from lung tissue.

Conclusions: We demonstrated that intestinal IR interferes with lung homeostasis, priming the tissue to generate proinflammatory mediators for at least 24 h postischemia. Furthermore, our data confirm that the inflammatory responses caused by intestinal IR are estradiol mediated.

Keywords: 17β-Estradiol; Cytokines; Inflammation; Intestinal ischemia and reperfusion; Lung; Uric acid.