NADPH Oxidase-Mediated Testicular Oxidative Imbalance Regulates the TXNIP/NLRP3 Inflammasome Axis Activation after Ischemia Reperfusion Injury

Abstract

Oxidative stress, inflammation and germ cell death are the main characteristics of testicular ischemia reperfusion injury (tIRI), which is considered as the underlying mechanism for testicular torsion and detorsion. The study aimed to examine the effect of tIRI-activated NADPH oxidase (NOX) on the expression of the NLRP3 inflammasome pathway components. Three groups of male Sprague–Dawley rats (n = 12 each) were studied: sham, unilateral tIRI only and tIRI treated with apocynin, a NOX-specific inhibitor. The tIRI rat model was subjected to 1 h of ischemia followed by 4 h of reperfusion. H&E staining, real time PCR, biochemical assays, and Western blot were utilized to evaluate spermatogenic damage, gene expression, oxidative stress markers, and NLRP3 pathway components, respectively. As a result of tIRI, decreased total antioxidant capacity and suppressed activities of superoxide dismutase and catalase were associated with spermatogenic arrest. The components of the NLRP3 inflammasome pathway (TXNIP, NLRP3, ASC, caspase-1, GSDMD, MMP-9) were upregulated transcriptionally and post-transcriptionally during tIRI. In parallel, tissue inflammation was demonstrated by a marked increase in the concentrations of myeloperoxidase, IL-1β, and IL-18. Apocynin treatment prevented testicular oxidative stress and inflammation. Thus, NOX inhibition by apocynin prevented ROS accumulation, proinflammatory cytokine overexpression and NLRP3 inflammasome activation during tIRI.

Keywords

• NADPH oxidase
• oxidative stress
• NLRP3 inflammasome
• testis
• ischemia reperfusion injury