Current status of the COVID-19 and male reproduction: A review of the literature.

BACKGROUND: Coronavirus disease 2019 (COVID-19), which causes serious respiratory illnesses such as pneumonia and lung failure, was first reported in mid-December 2019 in China and has spread around the world. In addition to causing serious respiratory illnesses such as pneumonia and lung failure, there have been conflicting reports about the presence of SARS-CoV-2 in the semen of patients who were previously diagnosed with COVID-19 and possible implications for the male reproductive tract. OBJECTIVE: The goal for the present study was to review the current status of the literature concerning COVID-19 and male reproduction. MATERIAL AND METHODS: An electronic literature search was done by using PubMed and Google Scholar databases. Relevant papers, concerning SARS-COV-2 and COVID-19 and male reproduction, published between January 2020 and December 2020 were selected, analyzed and eventually included in the present literature review. RESULTS: SARS-CoV-2 may infect any cell type expressing angiotensin-converting enzyme 2 (ACE2), including reproductive cells. Besides the presence of the SARS-CoV-2 receptor, the expression of host proteases, such as transmembrane serine protease 2 (TMPRSS2), is needed to cleave the viral S protein, allowing permanent fusion of the viral and host cell membranes. Here, we aimed to review the current status of the literature concerning COVID-19 and male reproduction. The lack of co-expression of ACE2 and TMPRSS2 in the testis suggests that sperm cells may not be at increased risk of viral entry and spread. However, the presence of orchitis in COVID-19-confirmed patients and compromised sex-related hormonal balance among these patients intrigues reproductive medicine. DISCUSSION: SARS-CoV-2 may use alternate receptors to enter certain cell types, or the expression of ACE2 and TMPRSS2 may not be detected in healthy individuals. CONCLUSION: COVID-19 challenges all medical areas, including reproductive medicine. It is not yet clear what effects, if any, the COVID-19 pandemic will have on male reproduction. Further research is needed to understand the long-term impact of SARS-CoV-2 on male reproductive function.

Potential mechanisms of SARS-CoV-2 action on male gonadal function and fertility: Current status and future prospects.

The novel coronavirus was recognised in December 2019 and caught humanity off guard. The virus employs the angiotensin-converting enzyme 2 (ACE2) receptor for entry into human cells. ACE2 is expressed on different organs, which is raising concern as to whether these organs can be infected by the virus or not. The testis appears to be an organ enriched with levels of ACE2, while the possible mechanisms of involvement of the male reproductive system by SARS-CoV-2 are not fully elucidated. The major focus of the present studies is on the short-term complications of the coronavirus and gains importance on studying the long-term effects, including the possible effects of the virus on the male reproductive system. The aim of this review was to provide new insights into different possible mechanisms of involvement of male gonads with SARS-CoV-2 including investigating the ACE2 axis in testis, hormonal alterations in patients with COVID-19, possible formation of anti-sperm antibodies (ASA) and subsequently immunological infertility as a complication of SARS-CoV-2 infection. Finally, we suggest measuring the sperm DNA fragmentation index (DFI) as a determiner of male fertility impairment in patients with COVID-19 along with other options such as sex-related hormones and semen analysis. Invasion of SARS-CoV-2 to the spermatogonia, Leydig cells and Sertoli cells can lead to sex hormonal alteration and impaired gonadal function. Once infected, changes in ACE2 signalling pathways followed by oxidative stress and inflammation could cause spermatogenesis failure, abnormal sperm motility, DNA fragmentation and male infertility.

COVID-19 Infection in the Human Reproductive Tract of Men and Nonpregnant Women.

SARS-CoV-2 is an enveloped non-segmented positive-sense RNA virus, classified as a beta coronavirus, responsible for the COVID-19 pandemic. Angiotensin-converting enzyme 2 (ACE2), reported as a SARS-CoV-2 receptor, is expressed in different human tissues (lung, intestine, and kidney) and in the testis, ovaries, uterus, and vagina. This suggests a potential risk to the human reproductive tract in COVID-19 patients. In addition, SARS-CoV-2 RNA has been detected in the blood, urine, facial/anal swabs, semen, and vaginal secretion, suggesting other potential means of transmission. However, little has been reported about SARS-CoV-2 infection in the male and nonpregnant female reproductive tracts, which may provide direct evidence on sexual transmission and fertility problems. Therefore, we focused this narrative review mainly on the distribution of ACE2 and SARS-CoV-2 positivity in the male and nonpregnant female reproductive tracts, providing an overview of the potential threat of COVID-19 to reproductive health and sexual transmission.

A review of severe acute respiratory syndrome coronavirus 2 infection in the reproductive system.

An outbreak of pneumonia associated with coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) occurred in Wuhan, China, in December 2019, and has been spread worldwide rapidly now. Over 5.3-million confirmed cases and 340,000 disease-associated deaths have been found till May 25, 2020. The potential pathophysiology for SARS-CoV-2 to affect the target is via the receptor, angiotensin-converting enzyme 2 (ACE2). ACE2 can be found in the respiratory, cardiovascular, gastrointestinal tract, urinary tract, and reproductive organs such as human ovaries and Leydig cells in the testis. This receptor plays a dominant role in the fertility function. Considering the crucial roles of testicular cells of the male reproductive system, increasing numbers of studies focus on the effects of SARS-CoV-2 on the testis. In this literature, we reviewed several studies to evaluate the relevance between SARS-CoV-2, ACE receptor, and female and male reproductive system and found that the risk of being attacked by SARS-CoV-2 is higher in males than in females. Since men infected with SARS-CoV-2 virus may have the risk of impaired reproductive performance, such as the orchitis and an elevated of luteinizing hormone (LH), and additionally, SARS-CoV-2 virus may be found in semen, although the latter is still debated, all suggest that we should pay much attention to sexual transmitted disease and male fertility after recovering from COVID-19.

Impact of SARS-CoV-2 on Male Reproductive Health: A Review of the Literature on Male Reproductive Involvement in COVID-19.

Coronavirus Disease 2019 (COVID-19) has created a global pandemic. Global epidemiological results show that elderly men are susceptible to infection of COVID-19. The difference in the number of cases reported by gender increases progressively in favor of male subjects up to the age group ≥60-69 (66.6%) and ≥70-79 (66.1%). Through literature search and analysis, we also found that men are more susceptible to SARS-CoV-2 infection than women. In addition, men with COVID-19 have a higher mortality rate than women. Male represents 73% of deaths in China, 59% in South Korea, and 61.8% in the United States. Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the pathogen of COVID-19, which is transmitted through respiratory droplets, direct and indirect contact. Genomic analysis has shown that SARS-CoV-2 is 79% identical to SARS-CoV, and both use angiotensin-converting enzyme 2 (ACE2) as the receptor for invading cells. In addition, Transmembrane serine protease 2 (TMPRSS2) can enhance ACE2-mediated virus entry. However, SARS-CoV-2 has a high affinity with human ACE2, and its consequences are more serious than other coronaviruses. ACE2 acts as a "gate" for viruses to invade cells and is closely related to the clinical manifestations of COVID-19. Studies have found that ACE2 and TMPRSS2 are expressed in the testis and male reproductive tract and are regulated by testosterone. Mature spermatozoon even has all the machinery required to bind SARS-CoV-2, and these considerations raise the possibility that spermatozoa could act as potential vectors of this highly infectious disease. This review summarizes the gender differences in the pathogenesis and clinical manifestations of COVID-19 and proposes the possible mechanism of orchitis caused by SARS-CoV-2 and the potential transmission route of the virus. In the context of the pandemic, these data will improve the understanding of the poor clinical outcomes in male patients with COVID-19 and the design of new strategies to prevent and treat SARS-CoV-2 infection.

Multiple Expression Assessments of ACE2 and TMPRSS2 SARS-CoV-2 Entry Molecules in the Urinary Tract and Their Associations with Clinical Manifestations of COVID-19.

BACKGROUND: Since December 2019, the novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), first spread quickly in Wuhan, China, then globally. Based on previously published evidence, ACE2 and TMPRSS2 are both pivotal entry molecules that enable cellular infection by SARS-CoV-2. Also, increased expression of pro-inflammatory cytokines, or a "cytokine storm," is associated with multiple organ dysfunction syndrome often observed in critically ill patients. METHODS: We investigated the expression pattern of ACE2 and TMPRSS2 in major organs in the human body, especially in specific disease conditions. Multiple sequence alignment of ACE2 in different species was used to explain animal susceptibility. Moreover, the cell-specific expression patterns of ACE2 and cytokine receptors in the urinary tract were assessed using single-cell RNA sequencing (scRNA-seq). Additional biological relevance was determined through Gene Set Enrichment Analysis (GSEA) using an ACE2-specific signature. RESULTS: Our results revealed that ACE2 and TMPRSS2 were highly expressed in genitourinary organs. ACE2 was highly and significantly expressed in the kidney among individuals with chronic kidney diseases or diabetic nephropathy. In single cells, ACE2 was primarily enriched in gametocytes in the testis and renal proximal tubules. The receptors for pro-inflammatory cytokines, especially IL6ST, were notably concentrated in endothelial cells, macrophages, spermatogonial stem cells in the testis, and renal endothelial cells, which suggested the occurrence of alternative damaging autoimmune mechanisms. CONCLUSION: This study provided new insights into the pathogenic mechanisms of SARS-CoV-2 that underlie the clinical manifestations observed in the human testis and kidney. These observations might substantially facilitate the development of effective treatments for this rapidly spreading disease.

Histopathology and Ultrastructural Findings of Fatal COVID-19 Infections on Testis.

PURPOSE: To evaluate the presence and analyze the pathological changes within the testes of patients who died or recovered from severe acute respiratory syndrome coronavirus 2 (COVID-19) complications. MATERIALS AND METHODS: Testis tissue was collected from autopsies of COVID-19 positive (n=6) and negative men (n=3). Formalin-fixed paraffin-embedded tissues were stained with hematoxylin and eosin (H&E) and subjected to immunofluorescence for angiotensin-converting enzyme 2 (ACE-2) expression. Fluorescent-labeled tissue slides were imaged on a quantitative pathology scope with various zoom levels allowing for qualitative and quantitative interpretation. Tissue from four COVID-19 positive autopsy cases and a live seroconverted patient was imaged with transmission electron microscopy (TEM). RESULTS: H&E histomorphology showed three of the six COVID-19 biopsies had normal spermatogenesis while the remaining three had impaired spermatogenesis. TEM showed the COVID-19 virus in testis tissue of one COVID-19 positive autopsy case and the live biopsy, H&E stain on the same autopsy case demonstrated interstitial macrophage and leukocyte infiltration. Immunofluorescent stained slides from six COVID-19 positive men demonstrated a direct association between increased quantitative ACE-2 levels and impairment of spermatogenesis. CONCLUSIONS: The novel COVID-19 has an affinity for ACE-2 receptors. Since ACE-2 receptor expression is high in the testes, we hypothesized that COVID-19 is prevalent in testes tissue of infected patients. This study suggests the male reproductive tract, specifically the testes, may be targets of COVID-19 infection. We found an inverse association between ACE-2 receptor levels and spermatogenesis, suggesting a possible mechanism of how COVID-19 can cause infertility.

Renin Angiotensin System, COVID-19 and Male Fertility: Any Risk for Conceiving?

The current knowledge concerning the connection between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the renin-angiotensin system (RAS) system in the male reproductive apparatus is still limited, so dedicated studies are urgently required. Concerns about the male fertility consequences of SARS-CoV-2 infection have started to emerge, since epidemiologic studies observed that this coronavirus affects male patients more frequently and with increased severity, possibly because of the hormone-regulated expression of angiotensin-converting enzyme 2 (ACE2) receptor. A disturbance in fertility is also expected based on studies of the previous SARS-CoV infection, which targets the same ACE2 receptor when entering the host cells. In addition, bioinformatics analyses reveal the abundant expression of ACE2 receptor in the male reproductive tissues, particularly in the testis. It has been proposed that pharmacological intervention favoring the angiotensin-(1-7)/ACE2/Mas receptor pathway and increasing ACE2 expression and activity could greatly prevent inflammatory lesions in this area. Finally, in laboratories performing assisted reproductive technologies it is recommended that more attention should be paid not only to sperm quality but also to safety aspects. Data about the potential infectivity of seminal fluid are in fact conflicting and do not exclude risks for both personnel and patients. The potential infectivity of SARS-CoV-2 in reproductive male tissues should be strongly considered and further investigated for the proper management of in vitro fertilization procedures.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and its effect on gametogenesis and early pregnancy.

SARS-CoV-2 infection and pregnancy has been the topic of hundreds of publications over the last several months; however, few studies have focused on the implications of infection in early pregnancy and reproductive tissues. Here, we analyzed available evidence pertaining to SARS-CoV-2 infection, in early pregnancy, and in reproductive tissues. We searched PubMed and Embase databases in accordance with guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) for publications from inception to June 4, 2020. Four reviewers screened titles and abstracts and obtained full-text articles for analysis. Sixty-two studies were included in the review. Biological plausibility for infection with SARS-CoV-2 exists in testis, ovaries, and placenta as they express ACE2 receptor activity. In males, SARS-CoV-2 infection could lead to functional abnormalities leading to spermatogenic failure and male infertility. In females, an alteration of the ACE2 cascade via SARS-CoV-2 infection could lead to impairment in important follicular and luteal processes. There is also evidence of significant placental pathology in SARS-CoV-2 infection, but it is unclear what effects there may be for early pregnancy, though available data suggest less severe effects compared to other respiratory virus outbreaks. Further investigation is needed regarding SARS-CoV-2 in reproductive function and early pregnancy.

Additional diagnostic testing of the 2019 novel coronavirus (SARS-CoV-2).

PURPOSE OF REVIEW: Within the last two decades several members of the Coronaviridae family namely Severe Respiratory Syndrome (SARS-CoV) and Middle East Respiratory Syndrome (MERS-CoV) have demonstrated epidemic potential. In late, 2019 an unnamed genetic relative, later named SARS-CoV-2 realized its potential in the highly populous neighborhoods of Wuhan, China. Unchecked, the virus rapidly spread among interconnected communities and related households before containment measures could be in acted. "Appropriate" diagnostic testing in response to the SARS-CoV-2 outbreak should be urgently considered. This perspective review gives particular attention to the potential diagnostic testing of the virus in semen and seminal fluids due to its high levels of angiotensin converting enzyme 2 (ACE2) precursor. RECENT FINDINGS: As many infectious viruses are stable in semen and have transmitted the respective diseases, the presence of SARS-CoV-2 should be tested in semen to assess their stabilities and half-life. As in case of Ebola virus, it was present in semen for longer period in a carrier man without any symptom. Additional hypothesis is that since ACE2 could serve as a mediator for the endocytosis of the previously SARS coronavirus, SARS-CoV-2 may enter the cells through similar mechanism. From the protein expression atlas, high levels of ACE2 precursor were found in intestines and testis. Hence, the testis and seminal fluids could be the host cell and/or reservoir. The results could be used as a suggestive guideline for the sexual activities after the discharge or declaration of disease free.

A comprehensive investigation of the mRNA and protein level of ACE2, the putative receptor of SARS-CoV-2, in human tissues and blood cells.

The outbreak of pneumonia caused by SARS-CoV-2 posed a great threat to global human health, which urgently requires us to understand comprehensively the mechanism of SARS-CoV-2 infection. Angiotensin-converting enzyme 2 (ACE2) was identified as a functional receptor for SARS-CoV-2, distribution of which may indicate the risk of different human organs vulnerable to SARS-CoV-2 infection. Previous studies investigating the distribution of ACE2 mRNA in human tissues only involved a limited size of the samples and a lack of determination for ACE2 protein. Given the heterogeneity among humans, the datasets covering more tissues with a larger size of samples should be analyzed. Indeed, ACE2 is a membrane and secreted protein, while the expression of ACE2 in blood and common blood cells remains unknown. Herein, the proteomic data in HIPED and the antibody-based immunochemistry result in HPA were collected to analyze the distribution of ACE2 protein in human tissues. The bulk RNA-seq profiles from three separate public datasets including HPA tissue Atlas, GTEx, and FANTOM5 CAGE were also obtained to determine the expression of ACE2 in human tissues. Moreover, the abundance of ACE2 in human blood and blood cells was determined by analyzing the data in the PeptideAtlas and the HPA Blood Atlas. We found that the mRNA expression cannot reflect the abundance of ACE2 factor due to the strong differences between mRNA and protein quantities of ACE2 within and across tissues. Our results suggested that ACE2 protein is mainly expressed in the small intestine, kidney, gallbladder, and testis, while the abundance of which in brain-associated tissues and blood common cells is low. HIPED revealed enrichment of ACE2 protein in the placenta and ovary despite a low mRNA level. Further, human secretome shows that the average concentration of ACE2 protein in the plasma of males is higher than those in females. Our research will be beneficial for understanding the transmission routes and sex-based differences in susceptibility of SARS-CoV-2 infection.

Do genetic polymorphisms in angiotensin converting enzyme 2 (ACE2) gene play a role in coronavirus disease 2019 (COVID-19)?

Although some demographic, clinical and environmental factors have been associated with a higher risk of developing coronavirus disease 2019 (COVID-19) and progressing towards severe disease, altogether these variables do not completely account for the different clinical presentations observed in patients with comparable baseline risk, whereby some subjects may remain totally asymptomatic, whilst others develop a very aggressive illness. Some predisposing genetic backgrounds can hence potentially explain the broad inter-individual variation of disease susceptibility and/or severity. It has been now clearly established that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing COVID-19, infects the host cell through biding and being internalized with angiotensin converting enzyme 2 (ACE2), a surface protein expressed in a noticeable number of human cells, especially in those of upper and lower respiratory tracts, heart, kidney, testis, adipose tissue, gastrointestinal system and in lymphocytes. Accumulating evidence now suggests that genetic polymorphisms in the ACE2 gene may modulate intermolecular interactions with the spike protein of SARS-CoV-2 and/or contribute to pulmonary and systemic injury by fostering vasoconstriction, inflammation, oxidation and fibrosis. We hence argue that the development of genetic tests aimed at specifically identifying specific COVID-19-susceptible or -protective ACE2 variants in the general population may be a reasonable strategy for stratifying the risk of infection and/or unfavorable disease progression.

SARS-CoV-2 presence in seminal fluid: Myth or reality.

Great concerns have been raised on SARS-CoV-2 impact on men's andrological well-being, and one of the critically unanswered questions is whether it is present or not in the seminal fluid of infected subjects. The expression of ACE2 and TMPRSS2 in the testis and in the male genital tract allows speculations about a possible testicular involvement during the infection, possibly mediated by local and/or systemic inflammation that might allow a high viral load to overcome the hemato-testicular barrier. To date, few investigations have been carried out to ascertain the presence of SARS-CoV-2 in the seminal fluid with contrasting results. Furthermore, the cumulative number of subjects is far too low to answer the question unambiguously. Therefore, great caution is still needed when evaluating this data; otherwise, we risk unleashing unmotivated concerns in the scientific world with troublesome consequences in reproductive medicine.