Macrophage migration inhibitory factor in the human epididymis and semen

Exosomes as Theranostic Agents in Reproduction System

Exosomes (Exos), belonging to extracellular vesicles, are cell-derived nano-sized vesicles with the potential to carry different kinds of biological molecules. Many studies have proved the impacts of exosomal cargo on several biological processes in female and male reproductive systems. It is also hypothesized that changes in exosomal cargo are integral to the promotion of certain pathological conditions, thus Exos can be used as valid biomarkers for the diagnosis of infertility and other abnormal conditions. Here, efforts are made to collect some recent data related to the physiological significance of Exos in the reproductive system, and their potential therapeutic effects. It is anticipated that the current review article will lay the groundwork for elucidating the source and mechanisms by which Exos control the reproductive system additionally supplying fresh methods and concepts for the detection and treatment of disorders associated with fertility for future studies.

Microfluidics facilitating the use of small extracellular vesicles in innovative approaches to male infertility

Sperm are transcriptionally and translationally quiescent and, therefore, rely on the seminal plasma microenvironment for function, survival and fertilization of the oocyte in the oviduct. The male reproductive system influences sperm function via the binding and fusion of secreted epididymal (epididymosomes) and prostatic (prostasomes) small extracellular vesicles (S-EVs) that facilitate the transfer of proteins, lipids and nucleic acids to sperm. Seminal plasma S-EVs have important roles in sperm maturation, immune and oxidative stress protection, capacitation, fertilization and endometrial implantation and receptivity. Supplementing asthenozoospermic samples with normospermic-derived S-EVs can improve sperm motility and S-EV microRNAs can be used to predict non-obstructive azoospermia. Thus, S-EV influence on sperm physiology might have both therapeutic and diagnostic potential; however, the isolation of pure populations of S-EVs from bodily fluids with current conventional methods presents a substantial hurdle. Many conventional techniques lack accuracy, effectiveness, and practicality; yet microfluidic technology has the potential to simplify and improve S-EV isolation and detection.

Comparative proteome profiling of seminal components reveal impaired immune cell signalling as paternal contributors in recurrent pregnancy loss patients

PROBLEM

Recurrent pregnancy loss (RPL) is usually evaluated from a women's perspective, however, recent evidence implies involvement of male factors as paternally expressed genes predominate placenta. During fertilization, prior to implantation the immune system purposefully produces early pregnancy factors with potent immunomodulatory properties for adaptation to antigenically dissimilar embryo. Therefore, it is hypothesized that paternal immunological factors play a role in RPL.

METHOD OF STUDY

Comparative proteome profiling (label free liquid chromatography mass spectroscopy: LC-MS/MS) of the seminal extracellular vesicles (SEVs), extracellular vesicle free seminal plasma (EVF-SP) and spermatozoa was carried out in semen of RPL patients (n = 21) and fertile donors (n = 21). This was followed by pathway and protein-protein interaction analysis, and validation of key proteins' expression (western blot).

RESULTS

A total of 68, 28 and 49 differentially expressed proteins in SEVs, EVF-SP and spermatozoa of RPL patients, respectively, were found to be involved in inflammatory response, immune cell signalling and apoptosis. In SEVs, underexpressed GDF-15 and overexpressed C3 imply distorted maternal immune response to paternal antigens leading to impaired decidualization. Dysregulated TGFβ signalling in EVF-SP surmises defective modulation of inflammatory response and induction of immune tolerance to seminal antigens in the female reproductive tract through generation of regulatory T cells. Retained histone variants in spermatozoa construe defective expression of early paternal genes, while underexpressed PTN may inflict defective angiogenesis resulting in expulsion of decidua.

CONCLUSIONS

Impaired modulation of immune response and improper placental development due to altered cytokine levels in seminal components may be the contributing paternal factors in RPL.

The role of extracellular vesicles in animal reproduction and diseases

Extracellular vesicles (EVs) are nanosized membrane-enclosed compartments that serve as messengers in cell-to-cell communication, both in normal physiology and in pathological conditions. EVs can transfer functional proteins and genetic information to alter the phenotype and function of recipient cells, which undergo different changes that positively affect their structural and functional integrity. Biological fluids are enriched with several subpopulations of EVs, including exosomes, microvesicles (MVs), and apoptotic bodies carrying several cargoes, such as lipids, proteins, and nucleic acids. EVs associated with the reproductive system are actively involved in the regulation of different physiological events, including gamete maturation, fertilization, and embryo and fetal development. EVs can influence follicle development, oocyte maturation, embryo production, and endometrial-conceptus communication. EVs loaded with cargoes are used to diagnose various diseases, including pregnancy disorders; however, these are dependent on the type of cell of origin and pathological characteristics. EV-derived microRNAs (miRNAs) and proteins in the placenta regulate inflammatory responses and trophoblast invasion through intercellular delivery in the placental microenvironment. This review presents evidence regarding the types of extracellular vesicles, and general aspects of isolation, purification, and characterization of EVs, particularly from various types of embryos. Further, we discuss EVs as mediators and messengers in reproductive biology, the effects of EVs on placentation and pregnancy disorders, the role of EVs in animal reproduction, in the male reproductive system, and mother and embryo cross-communication. In addition, we emphasize the role of microRNAs in embryo implantation and the role of EVs in reproductive and therapeutic medicine. Finally, we discuss the future perspectives of EVs in reproductive biology.

Extracellular vesicles in mammalian reproduction: a review

Over the last decades, extracellular vesicles (EVs) have been found to be implicated in a complex universal mechanism of communication between different cell types. EVs are nanostructures of lipid nature that have an exosomal or ectosomal biogenesis, responsible for the intercellular transport of proteins, lipids, carbohydrates, nucleic acids, ions, among other molecules. The content of EVs can vary due to various factors such as hormonal stimuli, non-physiological conditions, metabolic state, etc. Once EVs reach their target cell, they can modulate processes such as gene expression, metabolism, response to external factors, and can even be associated with the delivery of molecules involved in epigenetic inheritance processes in germ cells. In mammalian reproduction, EVs have been shown to play an important role, either in vivo or in vitro, modulating a variety of processes in sperm, oocytes and embryos, and in their respective environments. Moreover, EVs represent a biodegradable, harmless and specific vehicle, which makes them attractive allies to consider when improving assisted reproductive technologies (ARTs). Therefore, the present review aims to describe the content of the main EVs involved in mammalian reproduction and how they can vary due to different factors, as well as to detail how EVs modulate, directly or indirectly, different molecular processes in gametes and embryos. In addition, we will highlight the mechanisms that remain to be elucidated. We will also propose new perspectives according to the characteristics of each particular EV to improve the different ARTs.

Simulating nature in sperm selection for assisted reproduction

Sperm selection in the female reproductive tract (FRT) is sophisticated. Only about 1,000 sperm out of millions in an ejaculate reach the fallopian tube and thus have a chance of fertilizing an oocyte. In assisted reproduction techniques, sperm are usually selected using their density or motility, characteristics that do not reflect their fertilization competence and, therefore, might result in failure to fertilize the oocyte. Although sperm processing in in vitro fertilization (IVF) and intrauterine insemination (IUI) bypasses many of the selection processes in the FRT, selection by the cumulus mass and the zona pellucida remain intact. By contrast, the direct injection of a sperm into an oocyte in intracytoplasmic sperm injection (ICSI) bypasses all natural selection barriers and, therefore, increases the risk of transferring paternal defects such as fragmented DNA and genomic abnormalities in sperm to the resulting child. Research into surrogate markers of fertilization potential and into simulating the natural sperm selection processes has progressed. However, methods of sperm isolation - such as hyaluronic acid-based selection and microfluidic isolation based on sperm tactic responses - use only one or two parameters and are not comparable with the multistep sperm selection processes naturally occurring within the FRT. Fertilization-competent sperm require a panel of molecules, including zona pellucida-binding proteins and ion channel proteins, that enable them to progress through the FRT to achieve fertilization. The optimal artificial sperm selection method will, therefore, probably need to use a multiparameter tool that incorporates the molecular signature of sperm with high fertilization potential, and their responses to external cues, within a microfluidic system that can replicate the physiological processes of the FRT in vitro.

Early life stress affects the miRNA cargo of epididymal extracellular vesicles in mouse†

Sperm RNA can be modified by environmental factors and has been implicated in communicating signals about changes in a father's environment to the offspring. The small RNA composition of sperm could be changed during its final stage of maturation in the epididymis by extracellular vesicles (EVs) released by epididymal cells. We studied the effect of exposure to stress in early postnatal life on the transcriptome of epididymal EVs using a mouse model of transgenerational transmission. We found that the small RNA signature of epididymal EVs, particularly miRNAs, is altered in adult males exposed to postnatal stress. In some cases, these miRNA changes correlate with differences in the expression of their target genes in sperm and zygotes generated from that sperm. These results suggest that stressful experiences in early life can have persistent biological effects on the male reproductive tract that may in part be responsible for the transmission of the effects of exposure to the offspring.

The Impact of Semen Exposure on the Immune and Microbial Environments of the Female Genital Tract

Background: Semen induces an immune response at the female genital tract (FGT) to promote conception. It is also the primary vector for HIV transmission to women during condomless sex. Since genital inflammation and immune activation increase HIV susceptibility in women, semen-induced alterations at the FGT may have implications for HIV risk. Here we investigated the impact of semen exposure, as measured by self-reported condom use and Y-chromosome DNA (YcDNA) detection, on biomarkers of female genital inflammation associated with HIV acquisition. Methods: Stored genital specimens were collected biannually (mean 5 visits) from 153 HIV-negative women participating in the CAPRISA 008 tenofovir gel open-label extension trial. YcDNA was detected in cervicovaginal lavage (CVL) pellets by RT-PCR and served as a biomarker of semen exposure within 15 days of genital sampling. Protein concentrations were measured in CVL supernatants by multiplexed ELISA, and the frequency of activated CD4+CCR5+ HIV targets was assessed on cytobrush-derived specimens by flow cytometry. Common sexually transmitted infections (STIs) and bacterial vaginosis (BV)-associated bacteria were measured by PCR. Multivariable linear mixed models were used to assess the relationship between YcDNA detection and biomarkers of inflammation over time. Results: YcDNA was detected at least once in 69% (106/153) of women during the trial (median 2, range 1-5 visits), and was associated with marital status, cohabitation, the frequency of vaginal sex, and Nugent Score. YcDNA detection but not self-reported condom use was associated with elevated concentrations of several cytokines: IL-12p70, IL-10, IFN-γ, IL-13, IP-10, MIG, IL-7, PDGF-BB, SCF, VEGF, β-NGF, and biomarkers of epithelial barrier integrity: MMP-2 and TIMP-4; and with reduced concentrations of IL-18 and MIF. YcDNA detection was not associated with alterations in immune cell frequencies but was related to increased detection of P. bivia (OR = 1.970; CI 1.309-2.965; P = 0.001) at the FGT. Conclusion: YcDNA detection but not self-reported condom use was associated with alterations in cervicovaginal cytokines, BV-associated bacteria, and matrix metalloproteinases, and may have implications for HIV susceptibility in women. This study highlights the discrepancies related to self-reported condom use and the need for routine screening for biomarkers of semen exposure in studies of mucosal immunity to HIV and other STIs.

Role of aposomes and epididymosomes in sperm quality control: A light and transmission electron microscopic study in an experimental rat model

The epididymis responds to adverse conditions of misshapen spermatozoa resulting from pathological changes or toxic insults by secretion of a dense matrix that segregates the latter for complete disintegration and dissolution. The objective of this study was to find the source of this matrix and the role-player of disintegration and dissolution of misshapen spermatozoa. We chose Wistar strain male rat model to tackle this issue, and the rats were administered with aflatoxin B1 for 55 days so as to increase the incidence of misshapen spermatozoa. At the end of the treatment, different segments of epididymis were processed for microscopic observations. We found that parallel with abundant misshapen spermatozoa in the epididymis the principal cells of the initial segment secrete enormous membrane-bound apical blebs called aposomes, which contain epididymosomes. The aposomes were found to coalesce so as for the content to merge and form a dense matrix that entangles the misshapen spermatozoa and segregates them from viable spermatozoa. The epididymosomes associate with the misshapen spermatozoa, and the latter is processed to disintegration and total dissolution. Therefore, we assign the role of segregation of misshapen spermatozoa from viable ones to the dense matrix of aposomes and their disintegration and dissolution to the epididymosomes.

Roles of male reproductive tract extracellular vesicles in reproduction

Extracellular vesicles (EVs) are secreted cell-derived membrane structures present in all organisms across animal, bacterial, and plant phyla. These vesicles play important roles in cell-cell communication in many processes integral to health and disease. Recent studies demonstrate that EVs and their cargo have influential and conserved roles in male reproduction. While EVs have been isolated from virtually all specialized tissues comprising the male reproductive tract, they are best characterized in the epididymis (epididymosomes) and seminal fluid (seminal fluid extracellular vesicles or prostasomes). Broadly speaking, EVs promote reproductive success through supporting sperm development and function, as well as influencing the physiology of female reproductive tract cells after mating. In this review, we present current knowledge on the composition and function of male reproductive tract EV populations in both normal physiology and pathology, and argue that their functions identify them as critical regulators of fertility and fecundity.

"Emerging role of Novel Seminal Plasma Bio-markers in Male Infertility: A Review"

Male infertility has emerged as an important cause of infertility worldwide. There are many factors affecting male fertility and research is going on to know impact of various factors on sperm functions. Semen analysis is gold standard diagnostic test for male infertility, but it is crude method for estimation of male infertility as seminal composition gets affected by environmental factors, infections, other pathologies, hence, results of semen analysis either becomes normal/ambiguous, leading to failure of diagnosis and delayed treatment. Hence, with need of newer, better tests for assessing male factor infertility, seminal plasma is being tested for biomarkers. Seminal plasma is considered gold mine for male fertility as it contains molecules from male reproductive glands which play important role in sperm function. Study of seminal plasma molecules can give an idea about sperm concentration, motility, morphology and cause of infertility and can serve as biomarkers for male infertility. Present review briefs on some of these novel seminal plasma biomarkers which may play significant role in male fertility and can be used in future for better identification, assessment of infertile males.

METHODOLOGY

Literature from 1985 to 2019 was searched from various databases including PUBMED, SCOPUS, Google Scholar on seminal plasma biomarkers using keywords: "seminal plasma protein biomarkers", "novel seminal plasma markers and male infertility", "hormones in seminal plasma and male infertility", "oxidative stress and male infertility", "Reactive Oxygen Species and sperm DNA", "immunoinfertility".

INCLUSION CRITERIA

All full length original or review articles or abstracts on seminal plasma markers and male infertility published in English language in various peer-reviewed journals were considered.

EXCLUSION CRITERIA

Articles published in languages other than English were excluded from the study.

RESULTS

Seminal plasma is a big reservoir of molecules derived from the various male reproductive glands which can be used as potential biomarkers of male fertility.

CONCLUSION

Hence, seminal plasma biomarkers can be used in future for better assessment of male factor infertility, its causes and may play an important role in management of male factor infertility.

Immunocytochemical Localization of Olfactory-signaling Molecules in Human and Rat Spermatozoa

Expression of olfactory receptors (ORs) in non-olfactory tissues has been widely reported over the last 20 years. Olfactory marker protein (OMP) is highly expressed in mature olfactory sensory neurons (mOSNs) of the olfactory epithelium. It is involved in the olfactory signal transduction pathway, which is mediated by well-conserved components, including ORs, olfactory G protein (Golf), and adenylyl cyclase 3 (AC3). OMP is widely expressed in non-olfactory tissues with an apparent preference for motile cells. We hypothesized that OMP is expressed in compartment-specific locations and co-localize with an OR, Golf, and AC3 in rat epididymal and human-ejaculated spermatozoa. We used immunocytochemistry to examine the expression patterns of OMP and OR6B2 (human OR, served as positive olfactory control) in experimentally induced modes of activation and determine whether there are any observable differences in proteins expression during the post-ejaculatory stages of spermatozoal functional maturation. We found that OMP was expressed in compartment-specific locations in human and rat spermatozoa. OMP was co-expressed with Golf and AC3 in rat spermatozoa and with OR6B2 in all three modes of activation (control, activated, and hyperactivated), and the mode of activation changed the co-expression pattern in acrosomal-reacted human spermatozoa. These observations suggest that OMP expression is a reliable indicator of OR-mediated chemoreception, may be used to identify ectopically expressed ORs, and could participate in second messenger signaling cascades that mediate fertility.

Thiol based mechanism internalises interacting partners to outer dense fibers in sperm

The sperm tail outer dense fibres (ODFs) contribute passive structural role in sperm motility. The level of disulphide cross-linking of ODFs and their structural thickness determines flagellar bending curvature and motility. During epididymal maturation, proteins are internalized to modify ODF disulphide cross-linking and enable motility. Sperm thiol status is further altered during capacitation in female tract. This suggests that components in female reproductive tract acting on thiol/disulphides could be capable of modulating the tail stiffness to facilitate modulation of the sperm tail rigidity and waveform en route to fertilization. Understanding the biochemical properties and client proteins of ODFs in reproductive tract fluids will help bridge this gap. Using recombinant ODF2 (aka Testis Specific Antigen of 70 kDa) as bait, we identified client proteins in male and female reproductive fluids. A thiol-based interaction and internalization indicates sperm can harness reproductive tract fluids for proteins that interact with ODFs and likely modulate the tail stiffness en route to fertilization.

Exosomes of male reproduction

Exosomes are nanosized membrane vesicles secreted by wide variety of cells and found in abundance in biological fluids including semen. They contain cargo of lipids, proteins, microRNAs and mRNAs, and are known to play a major role in intracellular communication. Seminal exosomes mainly include epididymosomes and prostasomes. Most of the proteins associated with the epididymosomes are transferred to the sperm subcellular or membranous domains during their epididymal transit and are involved in the acquisition of fertilizing ability, modulation of motility and protection against oxidative stress. Proteins associated with prostasomes stimulate sperm motility and regulate the timing of capacitation to avoid premature induction of acrosome reaction. Furthermore, prostasomes protect the sperm from immune responses within the female reproductive tract. Overall, exosome-associated proteins play an indispensable role in maturation of spermatozoa and therefore, serve as an excellent biomarker in early diagnosis of male infertility.

Proteomics Profiling of Autologous Blood and Semen Exosomes from HIV-infected and Uninfected Individuals Reveals Compositional and Functional Variabilities

Blood and semen are important body-fluids that carry exosomes for bioinformation transmission. Therefore, characterization of their proteomes is necessary for understanding body-fluid-specific physiologic and pathophysiologic functions. Using systematic multifactorial proteomic profiling, we characterized the proteomes of exosomes and exosome-free fractions from autologous blood and semen from three HIV-uninfected and three HIV-infected participants (total of 24 samples). We identified exosome-based protein signatures specific to blood and semen along with HIV-induced tissue-dependent proteomic perturbations. We validated our findings with samples from 16 additional donors and showed that unlike blood exosomes (BE), semen exosomes (SE) are enriched in clusterin. SE but not BE promote Protein·Nucleic acid binding and increase cell adhesion irrespective of HIV infection. This is the first comparative study of the proteome of autologous BE and SE. The proteins identified may be developed as biomarkers applicable to different fields of medicine, including reproduction and infectious diseases.

The contribution of epididymosomes to the sperm small RNA profile

It is now well established that mature spermatozoa harbour a rich and diverse profile of small non-protein-coding regulatory RNAs (sRNAs). There is also growing appreciation that this sRNA profile displays considerable plasticity, being altered in response to paternal exposure to a variety of environmental stressors. Coupled with evidence that upon delivery to the oocyte at the moment of fertilisation, sperm-borne sRNAs are able to influence both early embryonic development and the subsequent health of the offspring, there is now interest in both the timing and degree of change in the composition of the sRNA cargo of sperm. Models in which such epigenetic changes are linked to the spermatogenic cycle are seemingly incompatible with the lack of overt phenotypic changes in the spermatozoa of affected males. Rather, there is mounting consensus that such changes are imposed on sperm during their transit and storage within the epididymis, a protracted developmental window that takes place over several weeks. Notably, since spermatozoa are rendered transcriptionally and translationally silent during their development in the testes, it is most likely that the epididymis-documented alterations to the sperm sRNA profile are driven extrinsically, with a leading candidate being epididymosomes: small membrane enclosed extracellular vesicles that encapsulate a complex macromolecular cargo of proteins and RNAs, including the sRNAs. Here, we review the role of epididymosome–sperm communication in contributing to the establishment of the sperm sRNA profile during their epididymal transit.

Effect of scrotal heating on sperm quality, seminal biochemical substances, and reproductive hormones in human fertile men

At present, male contraceptive methods are only vasectomy and condoms, so it is necessary to research on male contraceptive techniques. The aim of this study is to observe the effects of scrotal heating (SH) on semen parameters, seminal l-carnitine (LC), epidermal growth factor (EGF), macrophage migration inhibitory factor (MIF), reproductive hormones and sperm chromosome numbers of adult healthy men, and to provide the experimental data for male contraception. The scrotums of 30 healthy male volunteers were exposed to the condition of 40 to 43°C SH belt warming 40 minutes each day for successive 2 days per week. The course of SH was continuous for 3 months. Computer-assisted semen analysis and hypo-osmotic swelling test, sperm DNA integrity, l-carnitine, MIF and EGF, and sperm fluorescence in situ hybridization were performed before, during, and after SH. The serum level of follicle stimulating hormone (FSH), luteinizing hormone (LH), and testosterone (T) were measured by chemiluminescent immunoassay. The mean parameters of sperm concentration, vitality, and normal morphological sperm were significantly decreased in groups with sperms being collected during 1, 2, and 3 months of SH when compared with those in groups of pre-SH (P < 0.01). Statistically significant differences of sperm DNA fragmentation, normal sperm membrane functionality, levels of LC and MIF in semen, and LH, FSH, and T in serum were observed between the groups of before SH and after SH 3 months and the groups of during SH 1, 2, and 3 months (P < 0.001). The total rate of chromosome number for 13, 18, 21, X, and Y in the 3 months of SH was 13.7-fold greater (13.72%/1.69%) than before SH (P < 0.001). The constant SH can impact the semen quality, sperm DNA integrity, sperm chromosome, LC and MIF, and LH, FSH, and T in serum. Transient SH may be a new method for male contraception.

Distribution of CD68-, CD8-, MHCI- and MHCII-positive cells in the bull and ram testis and epididymis

The mammalian testis possesses a special immunological environment because of its properties of remarkable immune privilege and effective local innate immunity. The testicular immune privilege protects immunogenic germ cells from systemic immune attack, and local innate immunity is important in preventing testicular microbial infections. Thus, this study aimed to immunohistochemically demonstrate the distribution and localization of CD68-, CD8-, MHCI- and MHCII-positive immune cells in the testes and epididymes. Negative immunoreactivity was detected in the seminiferous tubule epithelium and peritubular myoid cells of the testes upon staining in CD68, CD8 and MHC Class I. Positive CD68 immunoreaction was determined in the Sertoli cells and some Leydig cells. The detection of positive cells for CD8 clearly indicated the presence of lymphocytes. Furthermore, the staining with MHCI intensity was ascertained to vary from weak to moderate in the Sertoli and Leydig cells and connective tissue cells. MHCII-positive immunoreactivity was determined in myoid cells and Leydig cells in the interstitial area. The epithelium of the epididymis showed positive staining for CD68 and CD8, but the stroma displayed a rather weak staining. In the ram epididymis, neither intraepithelial nor interstitial positive reaction was observed for MHCI. In the epididymis, the basal cells displayed a stronger staining for MHCII. In conclusion, these cells not only contribute to local immunity through their direct effects on the quality of fertility in males, but also contribute either directly or indirectly to immune privilege by minimizing the development of both autoimmune reactions and potentially harmful risks.

Molecular changes and signaling events occurring in spermatozoa during epididymal maturation

After leaving the testis, spermatozoa have not yet acquired the ability to move progressively and are unable to fertilize oocytes. To become fertilization competent, they must go through an epididymal maturation process in the male, and capacitation in the female tract. Epididymal maturation can be defined as those changes occurring to spermatozoa in the epididymis that render the spermatozoa the ability to capacitate in the female tract. As part of this process, sperm cells undergo a series of biochemical and physiological changes that require incorporation of new molecules derived from the epididymal epithelium, as well as post-translational modifications of endogenous proteins synthesized during spermiogenesis in the testis. This review will focus on epididymal maturation events, with emphasis in recent advances in the understanding of the molecular basis of this process.

Changes in Levels of Seminal Nitric Oxide Synthase, Macrophage Migration Inhibitory Factor, Sperm DNA Integrity and Caspase-3 in Fertile Men after Scrotal Heat Stress

Background

This study observes changes in levels of seminal nitric oxide (NO), nitric oxide synthase (NOS), macrophage migration inhibitory factor (MIF), sperm DNA integrity, chromatin condensation and Caspase-3in adult healthy men after scrotal heat stress (SHS).

Methods

Exposure of the scrotum of 25 healthy male volunteers locally at 40–43°C SHS belt warming 40 min each day for successive 2 d per week. The course of SHS was continuously 3 months. Routine semen analysis, hypo-osmotic swelling (HOS) test, Aniline blue (AB) staining, HOS/AB and terminal deoxynucleotidyl transferase-mediated d UDP nick-end labeling (TUNEL) were carried out before, during and after SHS. Seminal NO and NOS contents were determined by nitrate reduction method. The activated Caspase-3 levels of spermatozoa and MIF in seminal plasma were measured by the enzyme-linked immunosorbent assay (ELISA) method. Statistical significance between mean values was determined using statistical ANOVA tests.

Results

The mean parameters of sperm concentration, motile and progressive motile sperm and normal morphological sperm were significantly decreased in groups during SHS 1, 2 and 3 months compared with those in groups of pre-SHS (P<0.001). Statistically significant differences of sperm DNA fragmentation, normal sperm membrane, and Caspase-3 activity as well as the level of NO, NOS and MIF in semen were observed between the groups before SHS and after SHS 3 months and the groups during SHS 1, 2 and 3 months (P<0.001). After three months of the SHS, various parameters recovered to the level before SHS. WBC in semen showed a positively significant correlation with the levels of NO, NOS, MIF and Caspase-3 activity. The percentage of abnormal sperm by using the test of HOS showed a positively significant correlation with that of HOS/AB.

Conclusions

The continuously constant SHS can impact the semen quality and sperm DNA and chromatin, which may be contributed to the high level of NO, NOS, MIF and Caspase-3 by SHS.

Histological and morphometric study of the epididymus of Chinchilla lanigera Grey under controlled conditions in captivity

Chinchilla lanigera, native to the Andean Mountains of Perú, Chile, Bolivia and Argentina, is a specimen of great economic importance because of its fur. In mammals, spermatozoa originate in testes and are transported to the epididymis, where they undergo morphological and biochemical modifications known as sperm maturation, a basic step in the acquisition of their fertilizing ability. The aim of this work is the macroscopic and microscopic analysis of the epididymis of Chinchilla lanigera Grey and its sectorization based on a histomorphological study. The epididymis presents a clear segmentation into four regions: initial segment, caput, corpus and cauda. The epithelium lining the seminiferous tubules is pseudostratified, with principal cells with stereocilia and basal, clear, apical, narrow and halo cells. The histological analysis showed that principal and basal cells are the prevailing populations in all regions, also revealing narrow cells and the absence of clear cells in the initial segment. Each segment presents its different histological and morphometric characteristics, which supports the idea of the specific behaviour of each region, giving a segment-specific character to the process of sperm maturation in this species. No significant differences were found in the morphometric measurements or in the histological evaluation of the epididymis of samples collected in April and October. The fact that no differences were found between the samples collected during the two periods when the reproductive ability in nature is different suggests the importance of external factors in the control of the reproductive cycle of Chinchilla lanigera.

Semen variables and sperm membrane protein profile of Saanen bucks (Capra hircus) in dry and rainy seasons of the northeastern Brazil (3°S)

The Saanen is a highly productive breed, and for this reason, it has been raised in Brazil, but mostly under climate conditions completely different from where the breed originated. The objective of this study was to investigate variations in semen parameters and sperm membrane proteins from Saanen bucks (n = 7) raised in Northeastern Brazil, during dry season (September, October, and November) and rainy season (March, April, and May). We showed that during the dry season, sperm motility, concentration, and the percentage of normal sperm decreased as compared to the rainy season. Rectal temperatures of bucks had no significant (p > 0.05) variations during the dry and rainy seasons. However, temperatures of left and right skin testis were higher (p < 0.05) during the dry as compared to the rainy season. Expression of three proteins (lysine-specific demethylase 5D, adenosine triphosphate (ATP) synthase subunit d, and radial spoke head protein 9 homolog) in sperm membrane were more intense in rainy season and only one protein (cytosol aminopeptidase) had greater expression in the dry season of the year. Our results show that mechanisms of testicular thermoregulation of Saanen bucks did not prevent a decrease in seminal parameters during the dry season. This deterioration may be related to reduced expression of proteins associated with important functions in sperm membrane.

Stromal-dependent tumor promotion by MIF family members

Solid tumors are composed of a heterogeneous population of cells that interact with each other and with soluble and insoluble factors that, when combined, strongly influence the relative proliferation, differentiation, motility, matrix remodeling, metabolism and microvessel density of malignant lesions. One family of soluble factors that is becoming increasingly associated with pro-tumoral phenotypes within tumor microenvironments is that of the migration inhibitory factor family which includes its namesake, MIF, and its only known family member, D-dopachrome tautomerase (D-DT). This review seeks to highlight our current understanding of the relative contributions of a variety of immune and non-immune tumor stromal cell populations and, within those contexts, will summarize the literature associated with MIF and/or D-DT.

High-resolution helium ion microscopy of epididymal epithelial cells and their interaction with spermatozoa

We examined the rat and mouse epididymis using helium ion microscopy (HIM), a novel imaging technology that uses a scanning beam of He(+) ions to produce nanometer resolution images of uncoated biological samples. Various tissue fixation, sectioning and dehydration methods were evaluated for their ability to preserve tissue architecture. The cauda epididymidis was luminally perfused in vivo to remove most spermatozoa and the apical surface of the epithelial lining was exposed. Fixed epididymis samples were then subjected to critical point drying (CPD) and HIM. Apical stereocilia in principal cells and smaller apical membrane extensions in clear cells were clearly distinguishable in both rat and mouse epididymis using this technology. After perfusion with an activating solution containing CPT-cAMP, a permeant analog of cAMP, clear cells exhibited an increase in the number and size of membrane ruffles or microplicae. In contrast, principal cells did not exhibit detectable structural modifications. High-resolution HIM imaging clearly showed the ultrastructure of residual sperm cells, including the presence of concentric rings on the midpiece, and of cytoplasmic droplets in some spermatozoa. Close epithelium-sperm interactions were also detected. We found a number of sperm cells whose heads were anchored within the epididymal epithelium. In certain cases, the surface of the sperm cytoplasmic droplet was covered with vesicle-like structures whose size is consistent with that of epididymosomes. In conclusion, we describe here the first application of HIM technology to the study of the structure and morphology of the rodent epididymis. HIM technology represents a major imaging breakthrough that can be successfully applied to study the epididymis and spermatozoa, with the goal of advancing our understanding of their structure and function.

Microbiological investigation in male infertility: a practical overview

The roles of inflammation and/or infection of the male accessory sex glands are very important for the potential effects that these conditions may have on male fertility. The clinical andrologist should be aware of the pathophysiological role of the main determinants of sperm damage when these conditions occur, in particular, seminal leukocytes, oxidative stress and cytokines. In addition, it is important to have a good knowledge of the methodologies to be used in clinical practice. This article summarizes the methods used to look for and to identify the micro-organisms responsible for male urogenital tract infections. These include sperm culture, urine culture, urethral swabbing, the Meares–Stamey test and balanopreputial swabbing. Finally, we discuss the role of human papilloma virus infection in male infertility.

Epididymosomes, prostasomes, and liposomes: their roles in mammalian male reproductive physiology

Mammalian spermatozoa are unique cells in many ways, and the acquisition of their main function, i.e. fertilization capacity, is a multistep process starting in the male gonad and ending near the female egg for the few cells reaching this point. Owing to the unique character of this cell, the molecular pathways necessary to achieve its maturation also show some specific characteristics. One of the most striking specificities of the spermatozoon is that its DNA is highly compacted after the replacement of histones by protamines, making the classical processes of transcription and translation impossible. The sperm cells are thus totally dependent on their extracellular environment for their protection against oxidative stress, for example, or for the molecular changes occurring during the transit of the epididymis; the first organ in which post-testicular maturation takes place. The molecular mechanisms underlying sperm maturation are still largely unknown, but it has been shown in the past three decades that extracellular vesicles secreted by the male reproductive tract are involved in this process. This review will examine the roles played by two types of naturally occurring extracellular vesicles, epididymosomes and prostasomes, secreted by the epididymis and the prostate respectively. We will also describe how the use of artificial vesicles, liposomes, contributed to the study of male reproductive physiology.

Male accessory gland infection and sperm parameters (review)

Male accessory gland infection (MAGI) has been identified among those diagnostic categories which have a negative impact on the reproductive function and fertility in males (Rowe et al., World Health Organization Manual for the Standardised Investigation and Diagnosis of the Infertile Couple, Cambridge University Press, Cambridge, 1993). MAGI is a hypernym which groups the following different clinical categories: prostatitis, prostate-vesiculitis and prostate-vesiculo-epididymitis. Some of the characteristics they share are: common diseases, mainly have a chronic course, rarely cause obstruction of the seminal pathways, can have an unpredictable intracanicular spread to one or more sexual accessory glands of the reproductive tract, as well as to one or both sides. In this review, we show that all components involving the inflammatory response (from the agents which first trigger it to each component of the inflammatory response dynamic) can deteriorate conventional and/or non-conventional sperm parameters arising from one or more of the following mechanisms: altered secretory function of the epididymis, seminal vesicles, and prostate which reduce the antioxidant properties or scavenging role of the seminal plasma; deterioration of spermatogenesis; and (unilateral or bilateral) organic or functional sub-obstruction of the seminal tract.

Epididymis cholesterol homeostasis and sperm fertilizing ability

Cholesterol, being the starting point of steroid hormone synthesis, is a long known modulator of both female and male reproductive physiology especially at the level of the gonads and the impact cholesterol has on gametogenesis. Less is known about the effects cholesterol homeostasis may have on postgonadic reproductive functions. Lately, several data have been reported showing how imbalanced cholesterol levels may particularly affect the post-testicular events of sperm maturation that lead to fully fertile male gametes. This review will focus on that aspect and essentially centers on how cholesterol is important for the physiology of the mammalian epididymis and spermatozoa.

Post testicular sperm maturational changes in the bull: important role of the epididymosomes and prostasomes

After spermatogenesis, testicular spermatozoa are not able to fertilize an oocyte, they must undergo sequential maturational processes. Part of these essential processes occurs during the transit of the spermatozoa through the male reproductive tract. Since the sperm become silent in terms of translation and transcription at the testicular level, all the maturational changes that take place on them are dependent on the interaction of spermatozoa with epididymal and accessory gland fluids. During the last decades, reproductive biotechnologies applied to bovine species have advanced significantly. The knowledge of the bull reproductive physiology is really important for the improvement of these techniques and the development of new ones. This paper focuses on the importance of the sperm interaction with the male reproductive fluids to acquire the fertilizing ability, with special attention to the role of the membranous vesicles present in those fluids and the recent mechanisms of protein acquisition during sperm maturation.

Regulated upon activation normal T-cell expressed and secreted originating from the epididymis differentially associates with viable and defective spermatozoa

OBJECTIVE

To investigate the expression and cellular distribution of regulated upon activation normal T-cell expressed and secreted (RANTES) in the male reproductive system.

DESIGN

Basic research.

SETTING

University academic medical center.

PATIENT(S)

Three adult male organ donors.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Reverse transcriptase-polymerase chain reaction (RT-PCR), in situ hybridization, immunohistochemical staining, and immunofluorescence staining were used to examine the distribution of RANTES in human and mouse epididymis. Western blot was used to quantitate the levels of RANTES expression in mouse epididymis on postnatal days. Immunofluorescence staining was applied to detect RANTES association with spermatozoa from mouse epididymis.

RESULT(S)

The location of RANTES was restricted to ciliated cells of the efferent duct and apical, narrow, and basal cells of the epididymal ducts, in both humans and mouse. RANTES-positive basal cells were only identified in the epididymal ducts in humans. The signals of RANTES were first detected on day 28 and increased during mouse sexual maturation. We also observed that RANTES was bound on both normal and defective epididymal sperm, but in different patterns.

CONCLUSION(S)

RANTES is constitutively expressed in the epididymis and secreted into the lumen of epididymis throughout sexual maturity, and differentially associates with viable and defective spermatozoa.

ADAM7 is associated with epididymosomes and integrated into sperm plasma membrane

During epididymal transit, mammalian sperm acquire selected proteins secreted by the epididymis. We previously showed that a disintegrin and metalloprotease (ADAM) 7 is expressed specifically in the epididymis and transferred to the sperm surface during epididymal transit. Here, we show that mouse ADAM7 secreted to the epididymal lumen is associated with membranous vesicles known as epididymosomes. Furthermore, we found that ADAM7 can be transferred directly from epididymal vesicles to sperm and that it is an integral plasma membrane protein in sperm. Thus, our study provides new information regarding the unique mode of secretion and interaction of ADAM7 during the epididymis-to-sperm transfer process.

Structural heterogeneity and protein composition of exosome-like vesicles (prostasomes) in human semen

BACKGROUND

Human seminal fluid contains small exosome-like vesicles called prostasomes. Prostasomes have been reported previously to play an important role in the process of fertilization by boosting survivability and motility of spermatozoa, in addition to modulating acrosomal reactivity. Prostasomes have also been reported to present with sizes varying from 50 to 500 nm and to have multilayered lipid membranes; however, the fine morphology of prostasomes has never been studied in detail.

METHODS

Sucrose gradient-purified prostasomes were visualized by cryo-electron microscopy (EM). Protein composition was studied by trypsin in-gel digestion and liquid chromatography/mass spectrometry.

RESULTS

Here we report for the first time the detailed structure of seminal prostasomes by cryo-EM. There are at least three distinct dominant structural types of vesicles present. In parallel with the structural analysis, we have carried out a detailed proteomic analysis of prostasomes, which led to the identification of 440 proteins. This is nearly triple the number of proteins identified to date for these unique particles and a number of the proteins identified previously were cross-validated in our study.

CONCLUSION

From the data reported herein, we hypothesize that the structural heterogeneity of the exosome-like particles in human semen reflects their functional diversity. Our detailed proteomic analysis provided a list of candidate proteins for future structural and functional studies.

Compartmentalization of proteins in epididymosomes coordinates the association of epididymal proteins with the different functional structures of bovine spermatozoa

Epididymosomes are small membranous vesicles secreted by epithelial cells within the luminal compartment of the epididymis. In bovine, many proteins are associated with epididymosomes, and some of them, such as the glycosylphosphatidylinositol (GPI)-anchored protein P25b, macrophage migration inhibitory factor (MIF), and aldose reductase (AKR1B1), are transferred to spermatozoa during the epididymal maturation process. P25b is associated with detergent-resistant membrane (DRM) domains of epididymal spermatozoa, whereas MIF and AKR1B1 are cytosolic proteins associated with detergent-soluble fractions. In this study, we tested the hypothesis that DRM domains are also present in the epididymosomes and that P25b DRM-associated proteins in these vesicles are transferred to the DRMs of spermatozoa. The presence of DRMs in epididymosomes was confirmed by their insolubility in cold Triton X-100 and their low buoyant density in sucrose gradient. Furthermore, DRMs isolated from epididymosomes are characterized by the exclusive presence of ganglioside GM1 and by high levels of cholesterol and sphingomyelin. Biochemical analysis indicated that P25b is linked to DRM in epididymosomes, whereas MIF and AKR1B1 are completely excluded from these membrane domains. Proteolytic treatment of epididymosomes and immunoblotting studies showed that P25b is affected by trypsin or pronase proteolysis. In contrast, MIF and AKR1B1 are not degraded by proteases, suggesting that they are localized within epididymosomes. Interaction studies between epididymosomes and epididymal spermatozoa demonstrated that P25b is transferred from the DRM of epididymosomes to the DRM of the caput epididymal spermatozoa as a GPI-anchored protein. Together, these data suggest that specific localization and compartmentalization of proteins in the epididymosomes coordinate the association of epididymal proteins with the different functional structures of spermatozoa.

Direct effect of macrophage migration inhibitory factor on sperm function: possible involvement in endometriosis-associated infertility

OBJECTIVE

To evaluate the effect of macrophage migration inhibitory factor (MIF) on sperm capacitation, a maturational process that occurs in the female reproductive tract and enables spermatozoa to become fully competent at fertilizing the oocyte.

DESIGN

Incubation of Percoll-washed spermatozoa with varying concentrations of human recombinant MIF or fetal cord serum (positive control).

SETTING

Human reproduction research laboratories.

INTERVENTION(S)

Fresh semen samples obtained from healthy volunteers after a minimum of 2 days of sexual abstinence.

MAIN OUTCOME MEASURE(S)

Protein tyrosine phosphorylation by Western blotting, the acrosomal status upon binding to the Pisum sativum agglutinin conjugated to fluorescein isothiocyanate, and sperm motility by computer-assisted sperm analysis.

RESULTS

MIF displayed a dose-dependent effect on the phosphotyrosine content of p105 and p81, the two major tyrosine-phosphorylated proteins associated with human sperm capacitation. A significant induction of tyrosine phosphorylation was seen at 2 ng/mL of MIF for both p105 and p81, but a trend for a down-regulation of the basal tyrosine phosphorylation level was noted at elevated concentrations (12-24 ng/mL). MIF pretreatment of spermatozoa resulted in a dose-dependent change in the acrosome reaction induced by the Ca(2+) ionophore A23187. After being increased at 1-4 ng/mL MIF with a statistically significant effect observed at 4 ng/mL, the acrosome reaction gradually decreased and fell below the control levels at higher concentrations. Furthermore, a significant decrease in the motility of spermatozoa was observed after exposure to an elevated concentration of MIF (12 ng/mL).

CONCLUSION(S)

The present data indicate that MIF may play a physiological role in sperm capacitation but may have deleterious effects on sperm function at abnormal pathophysiological levels, which suggests a role in endometriosis-associated infertility.

Epididymosomes are involved in the acquisition of new sperm proteins during epididymal transit

During epididymal transit, spermatozoa acquire new proteins. Some of these newly acquired proteins behave as integral membrane proteins, including glycosylphosphatidylinositol (GPI)-anchored proteins. This suggests that the secreted epididymal proteins are transferred to spermatozoa by an unusual mechanism. Within the epididymal lumen, spermatozoa interact with small membranous vesicles named epididymosomes. Many proteins are associated with epididymosomes and the protein composition of these vesicles varies along the excurrent duct and differs from soluble intraluminal proteins. Some epididymosome-associated proteins have been identified and their functions in sperm maturation hypothesized. These include P25b, a zona pellucida binding protein, macrophage migration inhibitory factor, enzymes of the polyol pathway, HE5/CD52, type 5 glutathione peroxidase, and SPAM1 or PH-20. The electrophoretic patterns of proteins associated to epididymosomes are complex and some of these proteins are transferred to defined surface domains of epididymal spermatozoa. Epididymosomes collected from different epididymal segments interact differently with spermatozoa. This protein transfer from epididymosomes to spermatozoa is time-dependent, temperature-dependent and pH-dependent, and is more efficient in the presence of zinc. Some proteins are segregated to lipid raft domains of epididymosomes and are selectively transferred to raft domains of the sperm plasma membrane. Some evidence is presented showing that epididymosomes are secreted in an apocrine manner by the epididymal epithelial cells. In conclusion, epididymosomes are small membranous vesicles secreted in an apocrine manner in the intraluminal compartment of the epididymis and play a major role in the acquisition of new proteins by the maturing spermatozoa.

Imbalance in seminal fluid MIF indicates male infertility

Macrophage migration inhibitory factor (MIF) is a ubiquitous cytokine that functions in reproduction and plays an important role in sperm maturation and motility. Here we reveal a correlation between MIF levels in human seminal fluid and fertility status. We identify an abnormal biphasic profile of MIF in the seminal fluid of patients with impaired sperm parameters. Our findings may be of interest for the development of a diagnostic method for fertility status.

Imbalance in seminal fluid MIF indicates male infertility

Macrophage migration inhibitory factor (MIF) is a ubiquitous cytokine that functions in reproduction and plays an important role in sperm maturation and motility. Here we reveal a correlation between MIF levels in human seminal fluid and fertility status. We identify an abnormal biphasic profile of MIF in the seminal fluid of patients with impaired sperm parameters. Our findings may be of interest for the development of a diagnostic method for fertility status.

Comparison Between Epididymosomes Collected in the Intraluminal Compartment of the Bovine Caput and Cauda Epididymidis1

During their transit along the epididymidis, mammalian spermatozoa acquire new proteins involved in the acquisition of male gamete fertilizing ability. We previously described membranous vesicles called epididymosomes, which are secreted in an apocrine manner by the epididymal epithelium. Some selected proteins associated with epididymosomes are transferred to spermatozoa during epididymal transit. The present study compared epididymosomes collected from caput epididymal fluid with vesicles from the cauda epididymidis in the bull. Two-dimensional gel electrophoresis revealed major differences in protein composition of epididymosomes isolated from the caput and cauda epididymidis. LC-QToF analysis of major protein spots as well as Western blot analysis confirmed the differences in proteins associated with these two populations of epididymosomes. Biotinylated proteins associated with caput and cauda epididymosomes also revealed differences. When incubated with caput epididymal spermatozoa, epididymosomes prepared from these two segments transferred different protein patterns. By contrast, cauda epididymosomes transferred the same pattern of proteins to spermatozoa from the caput and cauda epididymidis. Transfer of biotinylated proteins from cauda epididymosomes to caput spermatozoa decreased in a dose-dependent manner when biotinylated epididymosomes were diluted with unbiotinylated vesicles. Caput epididymosomes added in excess were unable to inhibit transfer of biotinylated proteins from cauda epididymosomes to caput spermatozoa. Following transfer of biotinylated proteins from cauda epididymosomes to caput spermatozoa, addition of unbiotinylated cauda epididymosomes was unable to displace already transferred biotinylated proteins. These results established that epididymosomes from caput and cauda epididymidis have different protein composition and interact differently with maturing spermatozoa.

Immunohistochemical Detection of Macrophage Migration Inhibitory Factor in Fetal and Adult Bovine Epididymis: Release by the Apocrine Secretion Mode?

Originally defined as a lymphokine inhibiting the random migration of macrophages, the macrophage migration inhibitory factor (MIF) is an important mediator of the host response to infection. Beyond its function as a classical cytokine, MIF is currently portrayed as a multifunctional protein with growth-regulating properties present in organ systems beyond immune cells. In previous studies, we detected substantial amounts of MIF in the rat epididymis and epididymal spermatozoa, where it appears to play a role during post-testicular sperm maturation and the acquisition of fertilization ability. To explore its presence in other species not yet examined in this respect, we extended the range of studies to the bull. Using a polyclonal antibody raised against MIF purified from bovine eye lenses, we detected MIF in the epithelium of the adult bovine epididymis with the basal cells representing a prominently stained cell type. A distinct accumulation of MIF at the apical cell pole of the epithelial cells and in membranous vesicles localized in the lumen of the epididymal duct was obvious. In the fetal bovine epididymis, we also detected MIF in the epithelium, whereas MIF accumulation was evident at the apical cell surface and in apical protrusions. By immunoelectron microscopy of the adult bovine epididymis, we localized MIF in apical protrusions of the epithelial cells and in luminal membrane-bound vesicles that were found in close proximity to sperm cells. Although the precise origin of the MIF-containing vesicles remains to be delineated, our morphological observations support the hypothesis that they become detached from the apical surface of the epididymal epithelial cells. Additionally, an association of MIF with the outer dense fibers of luminal spermatozoa was demonstrated. Data obtained in this study suggest MIF release by an apocrine secretion mode in the bovine epididymis. Furthermore, MIF localized in the basal cells of the epithelium and in the connective tissue could be responsible for regulating the migration of macrophages in order to avoid contact of immune cells with spermatozoa that carry a wide range of potent antigens.