Seminal angiotensin II type 2 receptor (AT2R) as a new biomarker for idiopathic Oligo-asthenozoospermia

Background: Infertility is defined as failure to achieve pregnancy after 12 months of regular unprotected sexual intercourse. Angiotensin II can bind to two different receptors : angiotensin receptor type 1 (AT1R) and type 2 (AT2R). There is evidence that the components of renin-angiotensin system (RAS) are locally synthesized in the male reproductive tissues as in the epididymis, prostate, testes, seminal fluid, and spermatozoa.
Objective: The aim of the present study is to determine the presence of soluble AT2R in human seminal plasma and to evaluate its possible role as a new diagnostic biomarker for cases of idiopathic oligo-asthenozoospermia.
Patients and methods: This study was conducted as a case-control study at Mansoura University Hospitals and included 100 subjects. Participants were divided into 50 patients with idiopathic oligo-asthenozoospermia, and 50 healthy volunteers who had achieved conception within one year of continuous unprotected marital relationship with normal semen analysis. All participants were subjected to thorough history taking, complete clinical examination, Doppler US for varicocele and semen analysis. The soluble angiotensin II type 2 receptors (AT2R) were measured in the seminal plasma by angiotesnin II type 2 receptor ELISA kit.
Results: Seminal AT2R, α-glucosidase and acrosin activity index were significantly decreased in idiopathic oligo-asthenozoospermia group in comparison with the control group. Seminal AT2R and α-glucosidase were negatively correlated with WBCs. The sperm concentration, grade A motility, grade (A+B) motility, velocity, linear velocity, linearity index, and normal morphology exhibited highly significant positive correlations with seminal plasma AT2R and alpha-glucosidase. Seminal AT2R is highly significant negatively correlated to malondialdehyde.
Conclusion: The present study revealed that AT2R is present in human seminal plasma and has a positive correlation with sperm concentration and motility. In addition, AT2R was significantly lower in idiopathic oligo-asthenozoospermia patients compared with healthy controls. The positive correlation of AT2R expression with motility highlights its potential role in idiopathic oligo-asthenozoospermia. These findings point to the possible involvement of AT2R in infertility.