Antiacrosin antibodies and infertility. II. Gene immunization with human proacrosin to assess the effect of immunity toward proacrosin/acrosin upon protein activities and animal fertility

Epithelial and Neural Cadherin in Mammalian Fertilization: Studies in the Mouse Model

Successful mammalian fertilization requires a well-orchestrated sequence of molecular events leading to gamete fusion. Since this interaction involves Ca²⁺-dependent adhesion events, the participation of the Ca⁺²-dependent cell-cell adhesion proteins Epithelial (E-cad) and Neural (N-cad) cadherin is envisaged. We have previously reported the expression of E-cad and N-cad in human gametes and showed evidence of their involvement in sperm-oocyte adhesion events leading to fertilization. To overcome ethical limitations associated with the use of human gametes in fertilization-related studies, the mouse has been selected worldwide as the experimental model for over 4 decades. Herein, we report a detailed study aimed at characterizing the expression of E-cad and N-cad in murine gametes and their involvement in murine fertilization using specific antibodies and blocking peptides towards both adhesion proteins. E-cad and N-cad protein forms, as well as other members of the adhesion complex, specifically β-catenin and actin, were identified in spermatozoa, cumulus cells and oocytes protein extracts by means of Western immunoblotting. In addition, subcellular localization of these proteins was determined in whole cells using optical fluorescent microscopy. Gamete pre-incubation with anti-E-cad (ECCD-1) or N-cad (H-63) antibodies resulted in decreased (p < 0.05) In Vitro Fertilization (IVF) rates, when using both cumulus-oocytes complexes and cumulus-free oocytes. Moreover, IVF assays done with denuded oocytes and either antibodies or blocking peptides against E-cad and N-cad led to lower (p < 0.05) fertilization rates. When assessing each step, penetration of the cumulus mass was lower (p < 0.05) when spermatozoa were pre-incubated with ECCD-1 or blocking peptides towards E-cad or towards both E- and N-cad. Moreover, sperm-oolemma binding was impaired (p < 0.0005) after sperm pre-incubation with E-cad antibody or blocking peptide towards E-cad, N-cad or both proteins. Finally, sperm-oocyte fusion was lower (p < 0.05) after sperm pre-incubation with either antibody or blocking peptide against E-cad or N-cad. Our studies demonstrate the expression of members of the adherent complex in the murine model, and the use of antibodies and specific peptides revealed E-cad and N-cad participation in mammalian fertilization.

A cross-sectional study on the correlation between cytokines in a pelvic environment and tubal factor infertility

Background

This cross-sectional study aimed to evaluate the levels of tumor necrosis factor-alpha (TNF-ɑ), interleukin-8 (IL-8), interleukin-6 (IL-6), and transforming growth factor-beta 1 (TGF-β1) in patients with primary and secondary tubal factor infertility (TFI) compared with fertile subjects, and to compare immune indexes in the serum and peritoneal fluid samples obtained from patients with TFI.

Methods

The pelvic fluid and peripheral blood of patients with TFI diagnosed by hysteroscopy and laparoscopy were taken as the study objects. The pelvic fluid and peripheral blood of patients who underwent hysteromyomectomy at the same time were taken as the control group. The contents of TNF-ɑ, IL-8, IL-6, and TGF-β1 in serum and peritoneal fluid were determined by enzyme-linked immunosorbent assay, and the levels of these cytokines in serum and pelvic fluid were compared between the two groups.

Results

Patients with secondary TFI showed significantly higher levels of TNF-ɑ, IL-8, IL-6 and TGF-β1 in the serum (26.15 ± 3.51 vs. 19.61 ± 0.157, 32.18 ± 15.13 vs. 5.73 ± 1.99, 38.84 ± 3.46 vs. 30.48 ± 0.61, and 38.37 ± 3.14 vs. 32.25 ± 1.69, respectively) and peritoneal fluid samples (129.73 ± 183.4 vs. 34.63 ± 0.56, 111.44 ± 207.42 vs. 15.34 ± 0.41, 80.01 ± 109.91 vs. 15.67 ± 0.52, and 82.54 ± 115.99 vs. 45.34 ± 0.41, respectively) compared with the control group. Patients with primary TFI exhibited significantly elevated concentration of TNF-α, IL-8, IL-6 and TGF-β1 in the peritoneal fluid samples (36.88 ± 2.67 vs. 34.63 ± 0.56, 19.47 ± 3.51 vs. 15.34 ± 0.41, 80.01 ± 109.91 vs. 15.67 ± 0.52, and 82.54 ± 115.99 vs. 45.34 ± 0.41, respectively) when compared to the controls. In patients with secondary infertility, the levels of TNF-α (26.15 ± 3.51 vs. 129.73 ± 183.4), IL-8 (32.18 ± 15.13 vs. 111.44 ± 207.42), IL-6 (38.84 ± 3.46 vs. 80.01 ± 109.91) and TGF-β1 (38.37 ± 3.14 vs. 82.54 ± 115.99) in the serum were significantly lower than those in the peritoneal fluid, whereas no significant difference was observed in the primary TFI group between the serum and peritoneal fluid cytokines levels.

Conclusion

The expression of cytokines in the pelvic environment of patients with TFI is upregulated compared to patients who do not have infertility issues. The detection of cytokines TNF-ɑ, IL-6, IL-8, and TGF-β1 in the pelvic fluid of tubal infertility patients can allow for further understanding of the etiology of TFI.

Antisperm antibodies: invaluable tools toward the identification of sperm proteins involved in fertilization

The identification of sperm proteins involved in fertilization has been the subject of numerous investigations. Much interest has been dedicated to naturally occurring antisperm antibodies (ASA) and their impact in fertility. Their presence in men and women has been associated with 2-50% of infertility cases. ASA may impair pre- and post-fertilization steps. Experimental models have been developed using sperm proteins as immunogens to evaluate their involvement in sperm function. Our team has pursued investigations to assess ASA presence in biological fluids from patients consulting for infertility and their effect on fertilization. We found ASA in follicular fluids with ability of inducing the acrosome reaction and blocking sperm-zona pellucida interaction and used them to identify sperm entities involved in these events. We generated and utilized antibodies against proacrosin/acrosin to characterize the sperm protease system. We implemented an ELISA to detect proacrosin/acrosin antibodies in human sera and evaluated their impact upon fertility by developing in vitro assays and a gene immunization model. This review presents a summary of ASA history, etiology, current approaches for detection and effects upon fertility. ASA (naturally occurring, generated by animal immunization and/or of commercial origin) are invaluable tools to understand the molecular basis of fertilization, better diagnose/treat immunoinfertility and develop immunocontraceptive methods.

Modes of acrosin functioning during fertilization

Mammalian fertilization is a complex process that involves gamete recognition, penetration, and fusion. Biochemical studies that identified the role of acrosome components during sperm-ova interaction especially the zona pellucida (ZP) provided major advances in sperm cell biology. Acrosin (a typical serine protease) functions during fertilization in several significant ways which include: a) activation of acrosome components, b) secondary binding with the ZP, and c) hydrolysis of the ZP. However, studies using knockout (KO) acrosin-deficient mice cast doubt on the traditional role of acrosin in fertilization. The KO acrosin-deficient mice exhibit normal fecundity except for delayed fertilization. Despite the doubt cast on the traditional role of acrosin by the KO acrosin-deficient mouse studies, acrosin still remains a major protease involved in multiple processes of fertilization. In this review, we assess the functional profile of acrosin and briefly summarize recent findings on proteases involved in fertilization. We propose a refined scheme for the functional role of acrosin in fertilization. We particularly emphasize the role of acrosin in acrosome exocytosis and activation of other acrosome components based on advanced technology like structural X-ray analysis.