Seminal hyperviscosity is not associated with semenogelin degradation or sperm deoxyribonucleic acid damage: a prospective study of infertile couples

Surface protein profiling of prostate-derived extracellular vesicles by mass spectrometry and proximity assays

Extracellular vesicles (EVs) are mediators of intercellular communication and a promising class of biomarkers. Surface proteins of EVs play decisive roles in establishing a connection with recipient cells, and they are putative targets for diagnostic assays. Analysis of the surface proteins can thus both illuminate the biological functions of EVs and help identify potential biomarkers. We developed a strategy combining high-resolution mass spectrometry (HRMS) and  proximity ligation assays (PLA) to first identify and then validate surface proteins discovered on EVs. We applied our workflow to investigate surface proteins of small EVs found in seminal fluid (SF-sEV). We identified 1,014 surface proteins and verified the presence of a subset of these on the surface of SF-sEVs. Our work demonstrates a general strategy for deep analysis of EVs' surface proteins across patients and pathological conditions, proceeding from unbiased screening by HRMS to ultra-sensitive targeted analyses via PLA.

Treatment of semen samples with α-chymotrypsin alters the expression pattern of sperm functional proteins-a pilot study

Semen hyperviscosity delays the liquefaction of semen sample and is subjected to limited proteolysis by addition of α-chymotrypsin to reduce the viscosity. α-Chymotrypsin is a proteolytic enzyme involved in degradation of the proteins and polypeptides. Even though α-chymotrypsin improves the handling of hyperviscous samples, its effect on the sperm proteins is not clear. This study was aimed to evaluate the alteration in the expression of sperm functional proteins in samples treated with α-chymotrypsin. Among all the proteins examined in both donor and patient samples, HSPA2 (70 KDa), BAG6 (150 KDa), HIST1H2BA (14 KDa), SPA17 (17 KDa formed after cleavage of C-terminal calmodulin-binding domain), and OXPHOS complexes were undetectable in α-chymotrypsin-treated samples, while the expression of the native SPA17 (20 KDa) was significantly decreased in the α-chymotrypsin-treated samples in comparison with controls. The use of α-chymotrypsin for liquefaction of hyperviscous samples degrades functional proteins of spermatozoa. Intracellular proteins, such as OXPHOS complexes and HIST1H2BA, and sperm surface proteins (HSPA2, BAG6, and SPA17) were degraded in all treated samples. Whether treatment of samples with α-chymotrypsin affects the global proteomic outcome is unclear. More in-depth calibration studies are required to determine the appropriate concentration of α-chymotrypsin for processing hyperviscous semen samples without compromising its protein expression and function. Similarly, the effects of altered protein function on assisted reproductive techniques (ART), such as intrauterine insemination (IUI) and in vitro fertilization (IVF) outcome, are not known and require further research.

Relationship between Semenogelins bound to human sperm and other semen parameters and pregnancy outcomes

BACKGROUND

Semenogelins (SEMGs) are major components of human seminal vesicle secretions. Due to SEMG's sperm-motility inhibitor, a significant negative correlation between sperm motility and the proportion of SEMG-bound spermatozoa (SEMG+) was found in asthenozoospermic patients. SEMGs also show intrinsic inhibitory capability for sperm capacitation; however, studies on actual clinical specimens have not been conducted.

METHODS

To reveal the relationship between SEMGs and the fertilizing capacity of sperm from male infertile patients who are not restricted to asthenozoospermia, we measured the proportion of SEMG+ in the spermatozoa of 142 male infertile patients. The pregnancy outcomes in partners of these patients were retrospectively analyzed using questionnaires.

RESULTS

Among examined semen parameters, only the total SEMG-unbound sperm count showed a tendency to be different between the spontaneous pregnancy or intra-uterine-insemination-pregnancy groups and in-vitro-fertilization- or intracytoplasmic-sperm-injection-pregnancy groups. It was elevated in the former group, which includes patients who used in vivo fertilization.

CONCLUSIONS

The total SEMG-unbound sperm count would be a relevant parameter for in vivo fertilization. This result suggests that SEMGs inhibit ectopic capacitation before sperm reach the fertilization site and that the number of total SEMG-unbound sperm is a parameter directly linked to the possibility of in vivo fertilization.