Alpha1-antitrypsin protects the intestine from ischemia-reperfusion injury in a rat intestinal clamping model

Ischemia-reperfusion injury (IRI) remains a significant hurdle when blood flow is restored to ischemic tissue. Alpha1-antitrypsin (AAT), a serine protease inhibitor, has demonstrated strong anti-inflammatory properties, including inhibition of neutrophil recruitment and activation. In this study we aim to investigate its potential to mitigate intestinal IRI (IIRI).

The experimental protocol included two phases, performed in male Sprague-Dawley rats (250-350 g). Intravenous treatment was administered 10 min before ischemia induced by 60 min of superior mesenteric artery clamping. In the first phase, groups (N = 7/group) were: sham (PBS), AAT/60 (AAT60mg/kg+IRI), and AAT/100 (AAT100mg/kg+IRI), with 7-day survival as primary endpoint. Selecting AAT dose based on Phase 1 results, Phase 2 included three groups (N = 6/group): sham (PBS), control (PBS+IRI), and AAT (AAT+IRI). Reperfusion lasted 60 min, followed by animals sacrifice for sampling. Endpoints were transepithelial electrical resistance (TEER, villus length-adjusted), histological injury (Park-Chiu score), neutrophil infiltration (MPO immunohistochemistry), ileal cytokine levels (IL-6,IL-10,IL-1β,TNFα), and arterial blood analysis (blood gas, endotoxin, IL-6).

In phase 1, AAT/60 vs control 7-day survival was 100 % vs 14 % (p = 0.001)(AAT/100: 86 %), selecting AAT/60 for Phase 2. For AAT/60 vs control, mean(SD) TEER values were 18.87(8.36) vs 12.00(3.43)Ω·cm² (p = 0.991). Park-Chiu scores were 2(1) vs 4(1)(p = 0.029), with neutrophil infiltration of 0.61(0.14)% vs 1.28(0.64)% (p = 0.028). Lactate acidosis was reduced (lactate: 2.02(0.72) vs 4.00(0.70)mmol/L, p < 0.001; pH: 7.36(0.04) vs 7.28(0.02), p = 0.004), whereas arterial endotoxin levels, arterial IL-6 levels, and ileal cytokine expression were similar.

By modulating neutrophil activity, AAT appears to reduce IIRI local/systemic effects, leading to improved 7-day survival.