Intestinal ischaemia/reperfusion upregulates β-defensin-2 expression and causes acute lung injury in the rat

ObjectiveHuman β-defensin-2 (BD-2) is a positive ion antimicrobial peptide. We investigated the effects of intestinal ischaemia/reperfusion (II/R) on rat BD-2 mRNA and protein expressions in rat lung to address the potential role of BD-2 in acute lung injury (ALI) induced by II/R.MethodsRats were randomly divided into two groups (n = 36 each). (i) Sham control and (ii) II/R group (1 h superior mesenteric artery clamping, followed by reperfusion of different durations). In II/R group, 6 animals were sacrificed at 0 min, 15 min, 30 min, 60 min, 3 h and 6 h after reperfusion, and serum, lung tissue and bronchoalveolar lavage fluid were harvested. Samples were taken at the corresponding time points in the sham group. Lung histological changes were observed under microscope and the pulmonary permeability index (PPI) was calculated. The lung tissue levels of TNFα were detected by ELISA. BD-2 mRNA and protein expressions were examined by RT-PCR and western blotting techniques, respectively.ResultsALI induced by II/R was confirmed by pathological examination and significantly increased PPI (P < 0.05 or 0.01). II/R significantly increased the lung TNFα levels and upregulated the expressions of BD-2 mRNA and protein expressions (P < 0.05 or 0.01). BD-2 mRNA expression was significantly positively correlated to the lung TNFα level (r = 0.823, P < 0.01) and negatively correlated to PPI (r = −0.615, P < 0.05).ConclusionII/R can upregulate BD-2 mRNA and protein expressions in rat lung. BD-2 could be an innate protective factor against II/R-induced lung injury.