Spermatic correlations and characterization of a potential biomarker of fertility in humans: sperm protein SP22

Author(s)

Josiane de Lima Rosa

• Document type: Doctoral Thesis
• Press: Botucatu. 2019-04-29.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. Botucatu
• Defense date: 2019-02-25
• Advisor: Wilma De Grava Kempinas

Abstract

Infertility affects approximately 15% of couples in reproductive age and 50% of the cases are directly related to man. The decrease in male fertility is due to several conditions including congenital malformations, genetic and endocrine disorders, infectious and inflammatory diseases, sexual dysfunction and lifestyle. Sperm protein SP22 (22kDa) has been shown to be a male fertility biomarker since, in rats, it is well established that its concentration, in sperm extractions from the epididymal tail, correlates with the fertility of these gametes. However, to incorporate this protein as a fertility biomarker in epidemiological and clinical studies, quantitative data are required in humans. Thus, the present study aimed to standardize the SP22 quantification and immunolocalization technique, investigate possible correlations among conventional and functional seminal parameters of fertile and infertile men with the concentration of this protein and to evaluate its predictive potential as a non-invasive fertility biomarker. Therefore, two observational studies were performed: one case-control type and the other sectional type. The case-control study was carried out on 44 volunteers’s seminal samples from Botucatu city and region, aged between 20 and 50 years, who were placed according to fertility: fertile (one or more children) and infertile. The sectional study was carried out on 12 patients’s attendend by the Human Reproduction Center of the Botucatu Medical School – UNESP, also aged between 20 and 50 years. In both studies were excluded those couples whose female factor of infertility was present. Multiparametric protocols standardization for the spermatozoa functional evaluation by flow cytometry technique, conventional and functional seminal analyzes, quantification and immunolocalization of SP22 were performed. The correlation among some parameters were investigated. This study was approved by Research Ethics Committee of the Botucatu Medical School – UNESP and the individuals included provided written consent. Infertile volunteers exhibited a reduction in volume and total sperm number of ejaculated as well as in volume, sperm concentration and total sperm number of post-swim-up. Both infertile volunteers and infertile patients had a lower percentage of cells with normal morphology. Fast progressive motility was another seminal quality parameter that was shown to be reduced in infertile patients. In addition to changes in some seminal parameters, infertile volunteers also exhibit a reduction in serum concentration of LH. The analyzes of the determination coefficients indicated that the proposed multiparametric protocols are adequate. Although no significant differences were observed between groups regarding functional seminal parameters, damage plasma membrane was positively correlated with superoxide anion production in the mitochondrial matrix. Immunostaining revealed the presence of SP22, among other sites, in the equatorial segment of the sperm head. The concentration determination of SP22, performed to date, was not significantly different between fertile and infertile volunteers and was not correlated with any of the parameters investigated. Therefore, the evaluation of the remaining seminal samples, using affinity purified monoclonal antibodies, which is underway, will be fundamental to complement the present study. However, this is an important intial step in the characterizing of SP22 as a potential non-invasive biomarker predicitve of fertility/infertilty in humans that may support epidemiological and clinical studies (AU)

• FAPESP's process: 15/13941-3 - Characterization of sperm protein SP22 as a biomarker of fertility in men
• Grantee: Josiane de Lima Rosa
• Support Opportunities: Scholarships in Brazil - Doctorate