Interdependence of Oxidative Stress and Inflammation in Testicular Dysfunction

Abstract

Male infertility is caused by a network of interconnected endogenous mechanisms. Around 50% of male infertility cases are idiopathic. However, oxidative stress (OS) and inflammation have been independently implicated in male infertility. For instance, reduced semen capacity was noted as OS increases the level of reactive oxygen species (ROS) and testicular inflammation increases the number of leukocytes which inhibit its capacity. It is worthy of note that inflammation is intimately connected with OS and together may initiate a vicious cycle with the ability to upend the homeostasis in the testicular system. It has been reported that ROS and reactive nitrogen species (RNS) facilitated by inflammatory cells at the site of inflammation are key factors in the initiation of testicular OS, while proinflammatory gene expressions are also elevated by a signalling pathway triggered by a variety of ROS/RNS. As a result, cellular damage could be exacerbated and male reproductive functions disrupted. Sperm from infertile men have shown higher ROS levels along with increased amounts of proinflammatory proteins and cytokines, thereby supporting the interlink between OS and inflammation. Over the last several decades, a significant number of studies have been conducted seeking to unravel the interplay between OS and inflammation, especially in the testis. This review, therefore, intends to discuss the interdependent interaction between OS and inflammation in testicular dysfunction.