Non-Enzymatic Antioxidant Defense and Polymorphic Changes in Male Infertility

Male infertility is conditioned in up to 25% genetically, but environmental factors are equally important. Dependencies analyzed here in this area have not been studied using such an approach so far. Therefore, they are innovative and constitute an important aspect of multi-range interdependencies. That is why we analyzed factors shaping male reproductive condition: glutathione, bilirubin, uric acid, chemical elements (Ca, Na, Mn, Fe, Mo, Li, V, Co, Ag, Ba, Tl, Al, Ni, Sn, B, Pb, Be), and genetic polymorphism (genotypes CC and TT of IL-4v.C589T(rs2243250). We studied infertile men from polluted Poland region with semen perturbations and healthy with normozoospermia.

We described semen abnormalities according to standard criteria. The population of patients with infertility consisted of 76 men with different fertility disorders. The control group consisted of 87 men with normozoospermia. The majority of infertile men came from Central Poland. The collection of biological samples and seminological tests were conducted by qualified medicians from the andrology clinic and by the authors of this paper (semen morphological parameters). Seminological analyses were based on macro- and microscopic analysis of ejaculate to verify semen volume, time of liquefaction, sperm density, motility, presence of agglutination, presence of leukocytes, and percentage of pathological forms. Concentrations of chemical elements in the blood were analyzed (ICP-MS). In serum, non-enzymatic antioxidants (glutathione GSH, bilirubin, uric acid) and lipid peroxidation intensity were qualified (Cayman Chemicals Co.). In researching gene polymorphisms connected with male infertility, molecular analysis was conducted (PCR-RFLP) and applied to chromosome 5: gene IL-4v.C589T.

We found poorer antioxidative defense in infertile men, whilst the higher levels of uric acid, compared to healthy, may act as a deteriorating factor. High correlations between glutathione and uric acid in the infertile and healthy implicated that non-enzymatic antioxidants undergo mutual regulation. It also applies to patients with IL-4v.C589T polymorphism. Interactions between non-enzymatic antioxidants and chemical elements were particularly noticeable in men with CC genotype. The most important modulator appeared to be sodium, while boron was the most meaningful in the interactions. Higher concentration of bilirubin, uric acid, and GSH in men with TT (0.687 mg·dL-1, 6.097 mg·dL-1, 6.345 µM), compared to CC genotype (0.652 mg·dL-1, 4.980 mg·dL-1, 4.630 µM) suggest a better functionality of antioxidative barrier. Estimating the importance of unfavorable changes arising from oxidative stress about the functionality of non-enzymatic antioxidants and correlations with MDA in men's serum allows a complete look at the determinants of male infertility. Among genetic polymorphisms, genotypes TT and CC of IL-4v.C589T gene show their influence on generating fertility perturbations. They had an indirect but differentiated effect on antioxidant mechanisms involving bilirubin, uric acid, and glutathione. Therefore, we conclude that IL-4v.C589T polymorphism differentiated the body's response to environmental stressors. The results presented in our paper on IL-4v.C589T polymorphism and conclusions formulated on their basis are consistent with literature data, indicating the lack of a direct relationship between polymorphism studied and male infertility. However, the primary intention of this paper was, to a lesser extent, to exclude or confirm a direct relationship between studied polymorphism and male infertility. We wanted a broader approach to the subject and to establish relationships between genetic aspects and antioxidant parameters of defense mechanisms. Therefore, we were more interested in the status of antioxidant defense and its relationships to the genetic factor in groups of people with a fixed genotype. We obtained a more detailed picture of the sum of genetic aspects and parameters related to antioxidant defense.

Non-enzymatic defense, chemical elements, and genetic polymorphisms are related to and shape male reproductive potential. Our results may be helpful in the diagnosis of male infertility; they will enable the reduction of idiopathic cases and the implementation of targeted and more effective treatment. Identification of environmental stressors and their correlations with fertility disorders can help eliminate or reduce the impact of factors unfavorable to fertility. This shows the new importance of environmental and immunogenetic factors, oxidative stress, and genetic polymorphisms in male fertility.