COVID-19 and male reproductive system: pathogenic features and possible mechanisms

Semen proteomics reveals alterations in fertility-related proteins post-recovery from COVID-19

Introduction: Changes to sperm quality and decline in reproductive function have been reported in COVID-19-recovered males. Further, the emergence of SARS-CoV-2 variants has caused the resurgences of COVID-19 cases globally during the last 2 years. These variants show increased infectivity and transmission along with immune escape mechanisms, which threaten the already burdened healthcare system. However, whether COVID-19 variants induce an effect on the male reproductive system even after recovery remains elusive. Methods: We used mass-spectrometry-based proteomics approaches to understand the post-COVID-19 effect on reproductive health in men using semen samples post-recovery from COVID-19. The samples were collected between late 2020 (1st wave, n = 20), and early-to-mid 2021 (2nd wave, n = 21); control samples were included (n = 10). During the 1st wave alpha variant was prevalent in India, whereas the delta variant dominated the second wave. Results: On comparing the COVID-19-recovered patients from the two waves with control samples, using one-way ANOVA, we identified 69 significantly dysregulated proteins among the three groups. Indeed, this was also reflected by the changes in sperm count, morphology, and motility of the COVID-19- recovered patients. In addition, the pathway enrichment analysis showed that the regulated exocytosis, neutrophil degranulation, antibacterial immune response, spermatogenesis, spermatid development, regulation of extracellular matrix organization, regulation of peptidase activity, and regulations of calcium ion transport were significantly dysregulated. These pathways directly or indirectly affect sperm parameters and function. Our study provides a comprehensive landscape of expression trends of semen proteins related to male fertility in men recovering from COVID-19. Discussion: Our study suggests that the effect of COVID-19 on the male reproductive system persists even after recovery from COVID-19. In addition, these post-COVID-19 complications persist irrespective of the prevalent variants or vaccination status.

A Scientometric Evaluation of COVID-19 and Male Reproductive Research

The COVID-19 pandemic due to the SARS-CoV-2 coronavirus showed acute and prolonged effects on human health. In addition, over the past four years, there has been a tremendous surge in COVID-19-related scientific publications, as shown by bibliometric and scientometric studies. However, such analysis of the scientific literature is lacking in the area of male reproduction. The current scientometric study analyzes publication characteristics of articles related to male reproduction and COVID-19 infection. We used the Scopus database to analyze scientometric data (the number of publications, journals, countries, type of documents, and subject area) related to COVID-19 and male reproductive research. Our literature search identified 345 articles related to COVID-19 and male reproductive research. Most of the articles were published in the USA (n = 72), Italy (n = 55), and China (n = 51). Such research was mainly focused around medicine (57.1%), followed by biochemistry, genetics, and molecular biology (25.7%). Also, in the area of male reproduction, only 37.1% (n = 128) of the articles contributed towards original research, whereas 52.8% (n = 182) were review articles and editorials focusing more on sexual dysfunction than infertility. Such a small number of studies published on COVID-19-related effects on male reproduction warrants a significant increase in research, which is required to decipher the mechanism(s) underlying SARS-CoV-2 infection-associated impairment of male reproductive function.

Vitamin D Levels and Risk of Male Factor Infertility: A Mendelian Randomization Study

PURPOSE

No consensus exists about the causal relationship between vitamin D (VD) and male factor infertility due to heterogeneity and confounding factors even in randomized controlled trials (RCTs). This study aimed to investigate the causal association between 25 hydroxyvitamin D (25OHD) levels and male factor infertility through Mendelian randomization (MR) and provide complementary information for optimization of future RCTs.

MATERIALS AND METHODS

Two-sample MR analyses with four steps were performed. Single-nucleotide polymorphisms (SNPs) for VD were extracted from 417,580 Europeans in the UK Biobank, and the summary-level data of male factor infertility (825 cases and 85,722 controls) were extracted from the FinnGen.

RESULTS

Totally 99 SNPs robustly associated with the 25OHD were included, and a 1-unit increase in genetically predicted natural-log transformed 25OHD levels was associated with decreased risk of male factor infertility (odds ratio [OR], 0.62; 95% confidence interval [CI], 0.44-0.89; p=0.010), which was consistent in all three sensitivity analyses (MR-Egger, weighted median, and weighted mode methods). The conclusion still stands after removing SNPs which explained more variation in the male factor infertility than the 25OHD (OR, 0.61; 95% CI, 0.42-0.88; p=0.009; n=62), and which were associated with confounders (body mass index, type 2 diabetes, smoking, and coronary artery diseases) of male factor infertility (OR, 0.58; 95% CI, 0.39-0.85; p=0.005; n=55).

CONCLUSIONS

VD supplement to increase serum 25OHD levels may be clinically beneficial for male factor infertility in the general population. The well-designed RCTs should be performed in priority to address this question.

ACE2, Circumventricular Organs and the Hypothalamus, and COVID-19

The SARS-CoV-2 virus gains entry to cells by binding to angiotensin-converting enzyme 2 (ACE2). Since circumventricular organs and parts of the hypothalamus lack a blood-brain barrier, and immunohistochemical studies demonstrate that ACE2 is highly expressed in circumventricular organs which are intimately connected to the hypothalamus, and the hypothalamus itself, these might be easy entry points for SARS-CoV-2 into the brain via the circulation. High ACE2 protein expression is found in the subfornical organ, area postrema, and the paraventricular nucleus of the hypothalamus (PVH). The subfornical organ and PVH are parts of a circuit to regulate osmolarity in the blood, through the secretion of anti-diuretic hormone into the posterior pituitary. The PVH is also the stress response centre in the brain. It controls not only pre-ganglionic sympathetic neurons, but is also a source of corticotropin-releasing hormone, that induces the secretion of adrenocorticotropic hormone from the anterior pituitary. It is proposed that the function of ACE2 in the circumventricular organs and the PVH could be diminished by binding with SARS-CoV-2, thus leading to a reduction in the ACE2/Ang (1-7)/Mas receptor (MasR) signalling axis, that modulates ACE/Ang II/AT1R signalling. This could result in increased presympathetic activity/neuroendocrine secretion from the PVH, and effects on the hypothalamic-pituitary-adrenal axis activity. Besides the bloodstream, the hypothalamus might also be affected by SARS-CoV-2 via transneuronal spread along the olfactory/limbic pathways. Exploring potential therapeutic pathways to prevent or attenuate neurological symptoms of COVID-19, including drugs which modulate ACE signalling, remains an important area of unmet medical need.

Mast Cell Activation Syndrome in COVID-19 and Female Reproductive Function: Theoretical Background vs. Accumulating Clinical Evidence

Coronavirus disease 2019 (COVID-19), a pandemic disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, can affect almost all systems and organs of the human body, including those responsible for reproductive function in women. The multisystem inflammatory response in COVID-19 shows many analogies with mast cell activation syndrome (MCAS), and MCAS may be an important component in the course of COVID-19. Of note, the female sex hormones estradiol (E2) and progesterone (P4) significantly influence mast cell (MC) behavior. This review presents the importance of MCs and the mediators from their granules in the female reproductive system, including pregnancy, and discusses the mechanism of potential disorders related to MCAS. Then, the available data on COVID-19 in the context of hormonal disorders, the course of endometriosis, female fertility, and the course of pregnancy were compiled to verify intuitively predicted threats. Surprisingly, although COVID-19 hyperinflammation and post-COVID-19 illness may be rooted in MCAS, the available clinical data do not provide grounds for treating this mechanism as significantly increasing the risk of abnormal female reproductive function, including pregnancy. Further studies in the context of post COVID-19 condition (long COVID), where inflammation and a procoagulative state resemble many aspects of MCAS, are needed.

An immunoPET probe to SARS-CoV-2 reveals early infection of the male genital tract in rhesus macaques

The systemic nature of SARS-CoV-2 infection is highly recognized, but poorly characterized. A non-invasive and unbiased method is needed to clarify whole body spatiotemporal dynamics of SARS-CoV-2 infection after transmission. We recently developed a probe based on the anti-SARS-CoV-2 spike antibody CR3022 to study SARS-CoV-2 pathogenesis in vivo. Herein, we describe its use in immunoPET to investigate SARS-CoV-2 infection of three rhesus macaques. Using PET/CT imaging of macaques at different times post-SARS-CoV-2 inoculation, we track the 64Cu-labelled CR3022-F(ab')2 probe targeting the spike protein of SARS-CoV-2 to study the dynamics of infection within the respiratory tract and uncover novel sites of infection. Using this method, we uncovered differences in lung pathology between infection with the WA1 isolate and the delta variant, which were readily corroborated through computed tomography scans. The 64Cu-CR3022-probe also demonstrated dynamic changes occurring between 1- and 2-weeks post-infection. Remarkably, a robust signal was seen in the male genital tract (MGT) of all three animals studied. Infection of the MGT was validated by immunofluorescence imaging of infected cells in the testicular and penile tissue and severe pathology was observed in the testes of one animal at 2-weeks post-infection. The results presented here underscore the utility of using immunoPET to study the dynamics of SARS-CoV-2 infection to understand its pathogenicity and discover new anatomical sites of viral replication. We provide direct evidence for SARS-CoV-2 infection of the MGT in rhesus macaques revealing the possible pathologic outcomes of viral replication at these sites.

An immunoPET probe to SARS-CoV-2 reveals early infection of the male genital tract in rhesus macaques

The systemic nature of SARS-CoV-2 infection is highly recognized, but poorly characterized. A non-invasive and unbiased method is needed to clarify whole body spatiotemporal dynamics of SARS-CoV-2 infection after transmission. We recently developed a probe based on the anti-SARS-CoV-2 spike antibody CR3022 to study SARS-CoV-2 pathogenesis in vivo. Herein, we describe its use in immunoPET to investigate SARS-CoV-2 infection of three rhesus macaques. Using PET/CT imaging of macaques at different times post-SARS-CoV-2 inoculation, we track the 64Cu-labelled CR3022-F(ab')2 probe targeting the spike protein of SARS-CoV-2 to study the dynamics of infection within the respiratory tract and uncover novel sites of infection. Using this method, we uncovered differences in lung pathology between infection with the WA1 isolate and the delta variant, which were readily corroborated through computed tomography scans. The 64Cu-CR3022-probe also demonstrated dynamic changes occurring between 1- and 2-weeks post-infection. Remarkably, a robust signal was seen in the male genital tract (MGT) of all three animals studied. Infection of the MGT was validated by immunofluorescence imaging of infected cells in the testicular and penile tissue and severe pathology was observed in the testes of one animal at 2-weeks post-infection. The results presented here underscore the utility of using immunoPET to study the dynamics of SARS-CoV-2 infection to understand its pathogenicity and discover new anatomical sites of viral replication. We provide direct evidence for SARS-CoV-2 infection of the MGT in rhesus macaques revealing the possible pathologic outcomes of viral replication at these sites.

SARS-CoV-2 and its Implications for the Human Reproductive System: A Review Article

Context: The SARS-CoV-2 virus causes dysfunction of vital organs in the body. Concerns about the destructive effect of SARS-CoV-2 on human reproductive tissues and fertility have increased. Evaluation of the possible mechanisms by which SARS-CoV-2 causes infertility is essential for effective prevention and treatment. This review aims to assess the studies that have been conducted on SARS-CoV-2 impacts on the human reproductive system. Evidence Acquisition: This review study investigated articles indexed in PubMed, Science-Direct, Scopus, and google scholar databases from 2019 to 2021. The Keywords SARS-CoV-2, COVID-19, human reproductive system, testis, and ovary were searched in the mentioned databases. Results: The present study assessed the expression of SARS-CoV-2-specific receptors, the presence of the virus in the human reproductive system, and the mechanisms by which this virus can affect human fertility. Conclusions: SARS-CoV-2, like other viruses, may indirectly influence the male reproductive system through cytokine storms, inflammation-causing oxidative stress, and its possible complications. The direct effects of SARS-CoV-2 on the male reproductive system are also reported. The testis may be a potential target for the SARS-CoV-2 virus. The impact of the SARS-CoV-2 virus on women's reproductive performance is unknown and requires further investigation.

Multiorgan and Vascular Tropism of SARS-CoV-2

Although the respiratory tract is the main target of SARS-CoV-2, other tissues and organs are permissive to the infection. In this report, we investigated this wide-spectrum tropism by studying the SARS-CoV-2 genetic intra-host variability in multiple tissues. The virological and histological investigation of multiple specimens from a post-mortem COVID-19 patient was performed. SARS-CoV-2 genome was detected in several tissues, including the lower respiratory system, cardio-vascular biopsies, stomach, pancreas, adrenal gland, mediastinal ganglion and testicles. Subgenomic RNA transcripts were also detected, in favor of an active viral replication, especially in testicles. Ultra-deep sequencing allowed us to highlight several SARS-CoV-2 mutations according to tissue distribution. More specifically, mutations of the spike protein, i.e., V341A (18.3%), E654 (44%) and H655R (30.8%), were detected in the inferior vena cava. SARS-CoV-2 variability can contribute to heterogeneous distributions of viral quasispecies, which may affect the COVID-19 pathogeny.

Tip of the iceberg: erectile dysfunction and COVID-19

The novel severe acute respiratory syndrome coronavirus 2 caused the coronavirus 2019 (COVID-19) pandemic that resulted in more than 150 million infections and 3.5 million deaths globally. COVID-19 affected men more than women, emerging with more severe disease and higher mortality rates. Androgens may be responsible for the underlying reason of more severe disease, as androgen receptors have been implicated to mediate viral cell entry and infection. Besides, male reproductive organs have been reported to be affected by the especially severe disease, resulting in erectile dysfunction (ED). In this narrative review, we aimed to gather possible mechanisms of the development of ED led by COVID-19. Current evidence illuminates endothelial dysfunction, direct testicular damage, and the psychological burden of COVID-19 that are of the pathways of ED. Although the proposed underlying mechanisms partly fail to answer the questions by which COVID-19 leads to ED, it is important to monitor men who recovered from COVID-19 regarding the sexual dysfunction sequelae of infection and address the long‐term consequences.