Is there an impact of the COVID-19 pandemic on male fertility? The ACE2 connection

The impact and inflammatory characteristics of SARS-CoV-2 infection during ovarian stimulation on the outcomes of assisted reproductive treatment

Introduction

Despite the global prevalence of coronavirus disease 2019 (COVID-19), limited research has been conducted on the effects of SARS-CoV-2 infection on human reproduction. The aims of this study were to investigate the impact of SARS-CoV-2 infection during controlled ovarian stimulation (COS) on the outcomes of assisted reproductive treatment (ART) and the cytokine status of patients.

Methods

This retrospective cohort study included 202 couples who received ART treatment, 101 couples infected with SARS-CoV-2 during COS and 101 matched uninfected couples. The parameters of ovarian stimulation and pregnancy outcomes were compared between the two groups. The All-Human Inflammation Array Q3 kit was utilized to measure cytokine levels in both blood and follicular fluid.

Results

No difference was found in the number of good-quality embryos (3.3 ± 3.1 vs. 3.0 ± 2.2, P = 0.553) between the infected and uninfected groups. Among couples who received fresh embryo transfers, no difference was observed in clinical pregnancy rate (53.3% vs. 51.5%, P = 0.907). The rates of fertilization, implantation, miscarriage, ectopic pregnancy and live birth were also comparable between the two groups. After adjustments were made for confounders, regression models indicated that the quality of embryos (B = 0.16, P = 0.605) and clinical pregnancy rate (P = 0.206) remained unaffected by SARS-CoV-2 infection. The serum levels of MCP-1, TIMP-1, I-309, TNF-RI and TNF-RII were increased, while that of eotaxin-2 was decreased in COVID-19 patients. No significant difference was found in the levels of cytokines in follicular fluid between the two groups.

Conclusion

Asymptomatic or mild COVID-19 during COS had no adverse effects on ART outcomes. Although mild inflammation was present in the serum, it was not detected in the follicular fluid of these patients. The subsequent immune response needs further investigation.

Molecular changes in the testes of COVID-19 patients

After the sudden outbreak of the COVID-19 pandemic, scientists and clinicians around the world have significantly expanded understanding of the pathogenesis of the disease as well as the impact of SARS-CoV-2 on various organs and tissues. To date, it is accepted to consider the new coronavirus infection as a multisystem disease, but the data on the effect on fertility remains unclear. Previous works by other authors have presented controversial results, and there is no evidence of a direct effect of the new coronavirus on the male gonads. Thus, further studies are needed to verify the hypothesis that the testicles are the target organ for SARS-CoV-2. Groups were formed: Group I (n = 109; age from 25 to 75 years, Median (IQR) - 60 (23) years), cause of death - new coronavirus infection; Group II (n = 21, age from 25 to 75 years, Median (IQR) - 55 (29.5) years) - autopsy testicular material obtained outside the pandemic. We used RT-PCR to detect the presence of viral RNA in testicular tissue. In addition, we investigated the levels of proteins that provide viral invasion, such as ACE-2 and Furin. In the present study, we detected genetic material of a new coronavirus and increased proteins required for viral invasion in testicular tissue of patients with COVID-19 by RT-PCR. Thus, based on our findings, we assume that testicular tissue is potentially vulnerable to SARS-CoV-2.Communicated by Ramaswamy H. Sarma.

Impaired immune response against SARS-CoV-2 infection is the major factor indirectly altering reproductive function in COVID-19 patients: a narrative review

Coronavirus disease 2019 (COVID-19) is an infectious disease affecting multiple systems and organs, including the reproductive system. SARS-CoV-2, the virus that causes COVID-19, can damage reproductive organs through direct (angiotensin converting enzyme-2, ACE-2) and indirect mechanisms. The immune system plays an essential role in the homeostasis and function of the male and female reproductive systems. Therefore, an altered immune response related to infectious and inflammatory diseases can affect reproductive function and fertility in both males and females. This narrative review discussed the dysregulation of innate and adaptive systems induced by SARS-CoV-2 infection. We reviewed the evidence showing that this altered immune response in COVID-19 patients is the major indirect mechanism leading to adverse reproduction outcomes in these patients. We summarized studies reporting the long-term effect of SARS-CoV-2 infection on women's reproductive function and proposed the chronic inflammation and chronic autoimmunity characterizing long COVID as potential underlying mechanisms. Further studies are needed to clarify the role of autoimmunity and chronic inflammation (long COVID) in altered female reproduction function in COVID-19.

Diabetes Ketoacidosis and COVID-19: An Insight into the Pathophysiology

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Infection of SARS-CoV-2 causes severe pathological changes in mouse testis

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has affected more than 600 million people worldwide. Several organs including lung, intestine, and brain are infected by SARS-CoV-2. It has been reported that SARS-CoV-2 receptor angiotensin-converting enzyme-2 (ACE2) is expressed in human testis. However, whether testis is also affected by SARS-CoV-2 is still unclear. In this study, we generate a human ACE2 (hACE2) transgenic mouse model in which the expression of hACE2 gene is regulated by hACE2 promoter. Sertoli and Leydig cells from hACE2 transgenic mice can be infected by SARS-CoV-2 pseudovirus in vitro, and severe pathological changes are observed after injecting the SARS-CoV-2 pseudovirus into the seminiferous tubules. Further studies reveal that Sertoli and Leydig cells from hACE2 transgenic mice are also infected by authentic SARS-CoV-2 virus in vitro. After testis interstitium injection, authentic SARS-CoV-2 viruses are first disseminated to the interstitial cells, and then detected inside the seminiferous tubules which in turn cause germ cell loss and disruption of seminiferous tubules. Our study demonstrates that testis is most likely a target of SARS-CoV-2 virus. Attention should be paid to the reproductive function in SARS-CoV-2 patients.

Semen parameters and male reproductive potential are not adversely affected after three or more months of recovery from COVID-19 disease

Background

The male reproductive system may be a potential target for SARS-CoV-2 since the presence of ACE and TMPRS2 receptors. After a first report of the presence of SARS-CoV-2 in semen of COVID-19 patients, several papers reported that SARS-CoV-2 was not detected in the semen. However, some evidences indicated that COVID-19 disease could impair semen parameters. During the infection, or in a short period after, a reduction in sperm concentration and motility and an increase in DNA fragmentation were observed, even in asymptomatic patients. There is no conclusive data exploring whether this damage changes with time. We investigated whether COVID-19 disease has a negative impact on semen parameters and male reproductive potential after recovery.

Methods

In this longitudinal retrospective study, we enrolled 20 men who had COVID-19 disease. We compared sperm parameters in samples collected before COVID-19 and after infection (8.3 ± 4.8 months). We also evaluated the reproductive potential in pre- and post-COVID-19 infertility treatments of 8 self-controlled couples as well as in 40 cycles after COVID-19 infection of the male partner.

Results

For most patients, we obtained results of more than one semen analysis before and after COVID-19. After adjusting for age, days of sexual abstinence, frequency of ejaculations and presence of fever, we found no significant difference over time in any semen parameter. The interval between COVID-19 infection and subsequent infertility treatments was 10.7 ± 7.5 months. There were no differences in the embryological and clinical outcomes of infertility treatments performed before and after male infection. One couple obtained a single pregnancy in the post COVID-19 IUI. Normal fertilization (65%), cleavage (99%) and blastocyst development (40%) rates in treatments performed after male infection were within the expected range of competencies. A total of 5 singleton and 1 twin clinical pregnancies were obtained, and 6 healthy children were born. A total of 10 blastocysts have been cryopreserved.

Conclusion

Our data are reassuring that COVID-19 disease has no negative effect on semen quality and male reproductive potential when semen samples are collected three months or more after infection.

mRNA and Viral Vector COVID-19 Vaccines Do Not Affect Male Fertility: A Prospective Study

Purpose

To assess whether mRNA and viral vector coronavirus disease 2019 (COVID-19) vaccines detrimentally affected semen parameters.

Materials and Methods

In this prospective study, we enrolled 101 men vaccinated for COVID-19 (76% received mRNA vaccines, 20% viral vector vaccines, 2% a mixed formulation, and for 2 men no information about vaccine xlink:type was available) in 2021 and with a previous semen analysis. For each man we compared semen parameters before and after vaccination.

Results

Post-vaccine samples were obtained at a median of 2.3±1.5 months after the second dose. After vaccination, the median sample volume significantly decreased (from 3.0 to 2.6 mL, p=0.036), whereas the median sperm concentration, the progressive motility, and total motile sperm count increased (from 25.0 to 43.0 million/mL, p<0.0001; from 50% to 56%, p=0.022; from 34.8 to 54.6 million, p<0.0001, respectively). Thirty-four patients were oligospermic before the vaccine, and also in these patients we observed a significant increase of sperm parameters after vaccine. Finally, we confirmed the aforementioned results in men who received a mRNA or a viral vector vaccine.

Conclusions

The semen parameters following COVID-19 vaccination did not reflect any causative detrimental effect from vaccination, and for the first time we demonstrated that this applies to both mRNA and viral-vector vaccines. The known individual variation in semen and the reduced abstinence time before the post-vaccine sample collection may explain the increases in sperm parameters.

Mechanisms of SARS-CoV-2 and Male Infertility: Could Connexin and Pannexin Play a Role?

The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on male infertility has lately received significant attention. SARS-CoV-2, the virus that causes coronavirus disease (COVID-19) in humans, has been shown to impose adverse effects on both the structural components and function of the testis, which potentially impact spermatogenesis. These adverse effects are partially explained by fever, systemic inflammation, oxidative stress, and an increased immune response leading to impaired blood-testis barrier. It has been well established that efficient cellular communication via gap junctions or functional channels is required for tissue homeostasis. Connexins and pannexins are two protein families that mediate autocrine and paracrine signaling between the cells and the extracellular environment. These channel-forming proteins have been shown to play a role in coordinating cellular communication in the testis and epididymis. Despite their role in maintaining a proper male reproductive milieu, their function is disrupted under pathological conditions. The involvement of these channels has been well documented in several physiological and pathological conditions and their designated function in infectious diseases. However, their role in COVID-19 and their meaningful contribution to male infertility remains to be elucidated. Therefore, this review highlights the multivariate pathophysiological mechanisms of SARS-CoV-2 involvement in male reproduction. It also aims to shed light on the role of connexin and pannexin channels in disease progression, emphasizing their unexplored role and regulation of SARS-CoV-2 pathophysiology. Finally, we hypothesize the possible involvement of connexins and pannexins in SARS-CoV-2 inducing male infertility to assist future research ideas targeting therapeutic approaches.

Corona and Reproduction, or Why the Corona Vaccination Does Not Result in Infertility

Background As the COVID-19 pandemic persists and new vaccines are developed, concerns among the general public are growing that both infection with the SARS-CoV-2 virus and vaccinations against the coronavirus (mRNA vaccines) could lead to infertility or higher miscarriage rates. These fears are voiced particularly often by young adults of reproductive age. This review summarizes the current data on the impact of SARS-CoV-2 infection and corona vaccinations on female and male fertility, based on both animal models and human data.

Method A systematic literature search (PubMed, Embase, Web of Science) was carried out using the search terms “COVID 19, SARS-CoV-2, fertility, semen, sperm, oocyte, male fertility, female fertility, infertility”. After the search, original articles published between October 2019 and October 2021 were selected and reviewed.

Results Despite the use of very high vaccine doses in animal models, no negative impacts on fertility, the course of pregnancy, or fetal development were detected. In humans, no SARS-CoV-2 RNA was found in the oocytes/follicular fluid of infected women; similarly, no differences with regard to pregnancy rates or percentages of healthy children were found between persons who had recovered from the disease, vaccinated persons, and controls. Vaccination also had no impact on live-birth rates after assisted reproductive treatment. No viral RNA was detected in the semen of the majority of infected or still infectious men; however, a significant deterioration of semen parameters was found during semen analysis, especially after severe viral disease. None of the studies found that corona vaccines had any impact on male fertility.

Discussion Neither the animal models nor the human data presented in recent studies provide any indications that fertility decreases after being vaccinated against coronavirus. However, there is a growing body of evidence that severe SARS-CoV-2 infection has a negative impact on male fertility and there is clear evidence of an increased risk of complications among pregnant women with SARS-CoV-2 infection. The counseling offered to young adults should therefore take their fears and concerns seriously as well as providing a structured discussion of the current data.

Laboratory medicine in pandemic of COVID-19

After the outbreak in China in the year 2019, severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) quickly spread around the world causing a protracted pandemic. Approximately one-third of infections appear to be asymptomatic. Symptomatic disease is characterized primarily by symptoms of respiratory tract infection of varying severity. But Coronavirus Disease 2019 (COVID-19) is much more than an acute respiratory disease because SARS-CoV-2 affects many organs inducing a vast number of symptoms such as cardiovascular, neurological, gastrointestinal, dermatological, with numerous complications. Short and long-term effects of infection, severe ones, and especially mild forms of the disease which affect a huge number of patients need to be further investigated. Laboratory medicine has a crucial role in early diagnosis of the disease, recognition of the patients who need hospital care, and close monitoring of hospitalized patients to timely identify associated clinical complications as well as follow-up of patients with long-term COVID-19.

Effects of SARS CoV-2, COVID-19, and its vaccines on male sexual health and reproduction: where do we stand?

Since severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first discovered, there have been questions surrounding the effects of coronavirus disease 2019 (COVID-19), and more recently the COVID-19 vaccine, on men's health and fertility. Significant research has been conducted to study viral tropism, potential causes for gender susceptibility, the impact of COVID-19 on male sexual function in the acute and recovery phases, and the effects of the virus on male reproductive organs and hormones. This review provides a recent assessment of the literature regarding the impact of COVID-19 and its vaccine on male sexual health and reproduction.

Implications of testicular ACE2 and the renin-angiotensin system for SARS-CoV-2 on testis function

Although many studies have focused on SARS-CoV-2 infection in the lungs, comparatively little is known about the potential effects of the virus on male fertility. SARS-CoV-2 infection of target cells requires the presence of furin, angiotensin-converting enzyme 2 (ACE2) receptors, and transmembrane protease serine 2 (TMPRSS2). Thus, cells in the body that express these proteins might be highly susceptible to viral entry and downstream effects. Currently, reports regarding the expression of the viral entry proteins in the testes are conflicting; however, other members of the SARS-CoV family of viruses - such as SARS-CoV - have been suspected to cause testicular dysfunction and/or orchitis. SARS-CoV-2, which displays many similarities to SARS-CoV, could potentially cause similar adverse effects. Commonalities between SARS family members, taken in combination with sparse reports of testicular discomfort and altered hormone levels in patients with SARS-CoV-2, might indicate possible testicular dysfunction. Thus, SARS-CoV-2 infection has the potential for effects on testis somatic and germline cells and experimental approaches might be required to help identify potential short-term and long-term effects of SARS-CoV-2 on male fertility.

Investigating Impacts of CoronaVac Vaccination in Males on In Vitro Fertilization: A Propensity Score Matched Cohort Study

Purpose

This study aimed to evaluate the influences of SARS-CoV-2 vaccination (CoronaVac) on male fertility and investigate the impact of a history of the CoronaVac vaccination in males on gamete and embryo development and in vitro fertilization (IVF) outcomes.

Materials and Methods

A prospective cohort study enrolled couples undergoing IVF cycles between June and August 2021 at Reproductive Medicine Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology in China. According to the history of SARS-CoV-2 vaccination in males, the participants were divided into the vaccination group and the non-vaccination group. A self-controlled study of semen analyses for males before and after CoronaVac vaccination was conducted. Baseline characteristics were matched using propensity score matching. Participants were categorized into the unexposed group (non-vaccination) and exposed group (vaccination), and the population was 271 for each. Semen parameters and IVF outcomes were the main outcomes.

Results

Generally, no statistically significant differences were exhibited between the matched cohorts regarding embryo developmental parameters, including fertilization rate, cleavage rate, high-quality embryo rate, blastocyst formation rate, and available blastocyst rate, as well as clinical outcomes, such as implantation rate, biochemical pregnancy rate, and clinical pregnancy rate. Moreover, males after vaccination seemed to have fluctuating semen parameters including increased semen volume, lower motility, and decreased normal forms of sperm, while the motile sperm counts were similar. In addition, all semen parameters were above the lower reference limits.

Conclusions

Our findings suggested that CoronaVac vaccinations in males may not have adverse effects on patient performance or the gamete and embryonic development potential during assisted reproductive technology (ART) treatments.

Perspectives into the possible effects of the B.1.1.7 variant of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on spermatogenesis

B.1.1.7 is a recently discovered variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) associated with increased transmissibility. Recent findings indicate that this variant has a propensity to infect adolescents and children at higher rates than adults. The virus gains entry into various body cells utilizing angiotensin-converting enzyme 2 (ACE-2) and basigin (CD147) as receptors. The virus mainly affects type II pneumocytes of lungs, endothelial cells, enterocytes, and renal tubular cells. It is reported to affect testes, causing testicular pain, and producing histopathological changes, as observed in some autopsies. The B.1.1.7 variant can also affect various cells in the testes. This raises a major concern regarding the long-term effects of the viral infection on spermatogenesis and highlights the pressing need for a robust database of serum samples from infected male children.

Role of miR-2392 in driving SARS-CoV-2 infection

MicroRNAs (miRNAs) are small non-coding RNAs involved in post-transcriptional gene regulation that have a major impact on many diseases and provide an exciting avenue toward antiviral therapeutics. From patient transcriptomic data, we determined that a circulating miRNA, miR-2392, is directly involved with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) machinery during host infection. Specifically, we show that miR-2392 is key in driving downstream suppression of mitochondrial gene expression, increasing inflammation, glycolysis, and hypoxia, as well as promoting many symptoms associated with coronavirus disease 2019 (COVID-19) infection. We demonstrate that miR-2392 is present in the blood and urine of patients positive for COVID-19 but is not present in patients negative for COVID-19. These findings indicate the potential for developing a minimally invasive COVID-19 detection method. Lastly, using in vitro human and in vivo hamster models, we design a miRNA-based antiviral therapeutic that targets miR-2392, significantly reduces SARS-CoV-2 viability in hamsters, and may potentially inhibit a COVID-19 disease state in humans.

Will Procreation Ever Be The Same After COVID-19?

Medically assisted procreation will never be the same again after this China Virus epidemic. With billions of lives being affected by this damaging global pandemic, medically assisted procreation services were not left unharmed with far-reaching consequences. New challenges are now emerging concerning COVID-19, such as associated reproductive implications and the consequences of assisted and natural procreation in the presence of acute SARS-CoV-2 infection and delayed consequences after patient recovery. There is a hypothesis that testicular damage and subsequent infertility may result following COVID-19 infection and the possibility of sexual transmission, as SARS-CoV-2 has been identified in the semen of infected patients. Vaccine hesitancy in young women planning pregnancies has been heightened because of the spread of misinformation on social media stating that COVID-19 vaccines will cause sterility in women. Reassuring data from accidental pregnancies that have occurred in the clinical trials of approved COVID-19 vaccines indicate that vaccination does not harm fertility or increase the rate of miscarriage. Scientists have quickly related to good tissue practices in vitro fertilization and a rethink is on about encouraging biopsies and focusing on safe vitrification protocols keeping in mind that ova, sperm, and embryos could be possible vectors for disease transmission with the limited research on the SARS-CoV-2 virus. Going ahead with segmented IVF without delay, freezing the generated embryos and pushing back the embryo transfer after the pandemic appears to be the best strategy at present. An international group of researchers have proposed a prognostic stratification of more vulnerable infertility cases in order to plan a progressive restart of worldwide fertility treatments.

The Great Deceiver: miR-2392's Hidden Role in Driving SARS-CoV-2 Infection

MicroRNAs (miRNAs) are small non-coding RNAs involved in post-transcriptional gene regulation that have a major impact on many diseases and provides an exciting avenue towards antiviral therapeutics. From patient transcriptomic data, we have discovered a circulating miRNA, miR-2392, that is directly involved with SARS-CoV-2 machinery during host infection. Specifically, we show that miR-2392 is key in driving downstream suppression of mitochondrial gene expression, increasing inflammation, glycolysis, and hypoxia as well as promoting many symptoms associated with COVID-19 infection. We demonstrate miR-2392 is present in the blood and urine of COVID-19 positive patients, but not detected in COVID-19 negative patients. These findings indicate the potential for developing a novel, minimally invasive, COVID-19 detection method. Lastly, using in vitro human and in vivo hamster models, we have developed a novel miRNA-based antiviral therapeutic that targets miR-2392, significantly reduces SARS-CoV-2 viability in hamsters and may potentially inhibit a COVID-19 disease state in humans.

Investigating the impact of asymptomatic or mild SARS-CoV-2 infection on female fertility and in vitro fertilization outcomes: A retrospective cohort study

Background: The current study aimed to investigate the impact of asymptomatic or mild severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on female fertility and laboratory and clinical outcomes in assisted reproductive technology (ART) treatments. Methods: Patients undergoing ART treatments in the Reproductive Medicine Center, Tongji Hospital, Wuhan, from May 2020 to February 2021 were enrolled. Seventy of them were positive for serum SARS-CoV-2 antibodies (IgG and/or IgM), and 3973 patients had negative results. Propensity score matching with a ratio of 1:3 was performed, and there were 65 females in the case group and 195 females in the control group. Findings: The ovarian reserves and ovarian responses between groups after matching were similar. The proportions of mature oocytes, damaged oocytes, fertilized oocytes, cleavage embryos, high-quality embryos, and available blastocysts were also similar, despite a slight decrease in the blastocyst formation rate in the case group. In addition, there were no significant differences in terms of the biochemical pregnancy rate, clinical pregnancy rate, early miscarriage rate, or implantation rate. Interpretation: There is no evidence that a history of asymptomatic or mild SARS-CoV-2 infection in females may negatively affect female fertility, embryo laboratory outcomes, or clinical outcomes in ART treatments.

Health concerns regarding the effect of the COVID-19 pandemic on male fertility

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel coronavirus found in China in 2019. The disease caused by SARS-CoV-2, coronavirus disease 2019 (COVID-19), has been found to be closely related to the cells that secrete angiotensin-converting enzyme 2 (ACE2). ACE2 is involved in the renin-angiotensin system and is widely secreted in several tissues, including the testis, which has raised concerns because organs with high expression of the ACE2 receptor are susceptible to infection. Analyses have shown that in testicular cells, such as spermatogonia, seminiferous duct cells, Sertoli cells, and Leydig cells, there is a high expression level of ACE2. Therefore, SARS-CoV-2 may damage male reproductive tissues and cause infertility. Since male infertility is an important problem, scientists are evaluating whether COVID-19 may influence male infertility through the ACE2 receptor.

Heart Angiotensin-Converting Enzyme and Angiotensin-Converting Enzyme 2 Gene Expression Associated With Male Sex and Salt-Sensitive Hypertension in the Dahl Rat

Angiotensin-converting enzyme 2 (ACE 2) in the heart including its sex dependency in the hypertensive heart, has not been much studied compared to ACE. In the present study, we used the Dahl salt-sensitive rat exposed to fructose and salt to model a hypertensive phenotype in males, females, and ovariectomized females. Blood pressure was measured by the tale-cuff technique in the conscious state. Expression of RAS-related genes ACE, ACE2, angiotensin II receptor type 1, Mas1, and CMA1 in the heart were quantified. The results revealed small but significant differences between male and female groups. The main results indicate the presence of a male preponderance for an increase in ACE and ACE2 gene expression. The results are in accordance with the role of androgens or male chromosomal complement in controlling the expression of the two ACE genes.

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

Multiorgan dysfunction is the main characteristic of severe COVID-19 patients and the involvement of male reproductive system may occur among these patients. Although there is a limited evidence to confirm the orchitis and virus presence in the semen of patients, there are concerns about the transmission of virus through the semen. In addition, reduced fertility or infertility can be seen as consequences of severe COVID-19 in recovered subjects. In this study, we aimed to review articles related to COVID-19 and male reproductive system to find the possible underlying mechanisms of SARS-CoV-2 in affecting male fertility. The following keywords of SARS-CoV-2, COVID-19, testis, orchitis, semen, angiotensin-converting enzyme 2 (ACE2), hypothalamic-pituitary-testicular (HPT) axis, Hypothalamus, etc., were defined to find the related publications from standard search engines, e.g., PUBMED, SCOPUS, Google Scholar. According to studies, COVID-19 occurs in severe patients as respiratory disease, along with multi-organ failure. The most important mechanisms are classified as direct and indirect pathogenesis of SARS-CoV-2. The presence of ACE2 on the cell surface of various cells in testis increases the risk of direct infection by this virus. SARS-CoV-2 also affects the testis through the cytokine storm. In addition, the important role of HPT axis dysregulation through impaired Leydig cells and hypothalamus should be considered. Using antiviral and immunomodulatory therapy can be harmful for testis function. Further investigations are required to investigate potential mechanisms of male infertility in survivals of COVID-19. Since involvement of testis is essential for fertility, increasing the knowledge of health system may improve the outcomes.

Effects of Infection with SARS-CoV-2 on the Male and Female Reproductive Systems: A Review

Coronavirus Disease-2019 (COVID-19) is a rapidly spreading pandemic that began at the end of 2019. COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Reproductive health has always been one of the most important healthcare problems, and the impacts of COVID-19 on the reproductive systems have become an emerging topic. The effects of infection with SARS-CoV-2 on males are more harmful than on females. The outcomes of pregnancy also can show the condition of male and female reproductive system health. The vertical transmission of SARS-CoV-2 significantly affects pregnancy healthy. SARS-CoV-2, antibody, and other factors, such as the decline of lymphocyte counts, and increased erythrocyte sedimentation rate, C-reactive protein, and D-dimer levels, are evidence of SARS-CoV-2 vertical transmission. Angiotensin-converting enzyme 2 (ACE2) is regarded as a virus receptor in the reproductive system. The expression and activity of ACE2 are influenced by sex hormones, especially the male sex hormones. The strength of immunity is crucial to fighting off viral infection. Antibodies against SARS-CoV-2 show different expression in male and female patients, and the antibodies have been regarded as having potential applications in COVID-19 prevention and treatment.

This review aims to present the current status of what is known about the involvement of the male and female reproductive systems, as well as the effects on pregnancy health, during infection with SARS-CoV-2, and discusses the implications for future fertility.

The probable destructive mechanisms behind COVID-19 on male reproduction system and fertility

PURPOSE

The present study aims to summarize the current understanding of probable mechanisms and claims of adverse effects of SARS-CoV-2 on male fertility potential.

METHODS

Our search was including original articles, reviews, guidelines, letters to the editor, comments on guidelines, and editorials, regarding the male reproductive system. We used the words SARS-CoV-2, coronavirus, severe acute respiratory syndrome coronavirus 2, "2019 ncov," testis, sperm, male factor infertility, fertility treatment, semen, assisted reproductive technology (ART), sexual transmission, and ACE2.

RESULTS

Data showed coronavirus affects men more than women because of more expression of 2019 nCoV receptors (ACE2 and TMPRSS2) in testicular cells. Also, "Bioinformatics Analysis" suggests that sperm production may be damaged, since "Pseudo Time Analysis" has shown disruption in spermatogenesis. "Gene Ontology" (GO) showed an increase in viral reproduction and a decrease in sperm production-related terms. Recently, SARS-COV-2 mRNA and protein were detected in the semen of patients that had recovered from SARS-CoV-2 infection. Therefore, the probable disruption of blood-testis barrier (BTB) in febrile diseases is suspected in the acute phase of the disease enabling viral entry into the testes. Not only is spermatogenesis disturbed, but also disturbs gonadotropin, androgens, and testosterone secretion during SARS-CoV-2 infection. No sexual transmission has been reported yet; however, detection of the virus in semen still makes the sexual transmission an open question.

CONCLUSION

There is a concern that male fertility may be disturbed after the SARS-CoV-2 infection. Therefore, follow-up of the reproductive functions and male fertility may be necessary in recovered cases, especially in aged men.

Review of Sertoli cell dysfunction caused by COVID-19 that could affect male fertility

Spermatogenesis is a complex and elaborate differentiation process and is vital for male fertility. Sertoli cells play a major role in fertility and induce spermatogenesis by protecting, nourishing, and supporting germ cells. It has been speculated that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could directly affect the male reproductive system, and therefore heredity and fertility. The similarity of SARS-CoV-2 to SARS-CoV could confirm this hypothesis because both viruses use angiotensin-converting enzyme (ACE2) as the receptor to enter human cells. ACE2 is expressed by Sertoli cells and other testicular cells, therefore COVID-19 has the potential to impair fertility by destroying Sertoli cells. This hypothesis should be evaluated and confirmed by monitoring fertility in patients with COVID-19.

Air Pollution and COVID-19: A Possible Dangerous Synergy for Male Fertility

Several studies indicate that semen quality has strongly declined in the last decades worldwide. Air pollution represents a significant co-factor with the COVID-19 impact and has negative effects on the male reproductive system, through pro-oxidant, inflammatory and immune-dysregulating mechanisms. It has recently been reported that chronic exposure to PM2.5 causes overexpression of the alveolar ACE2 receptor, the entry route of SARS-CoV-2 into the organism shared by the lungs and testis where expression is highest in the body. In the testis, the ACE2/Ang-(1-7)/MasR pathway plays an important role in the regulation of spermatogenesis and an indirect mechanism of testicular damage could be due to the blockade of the ACE2 receptor by SARS-CoV-2. This prevents the conversion of specific angiotensins, and their excess causes inflammation with the overproduction of cytokines. PM2.5-induced overexpression of the alveolar ACE2 receptor, in turn, could increase local viral load in patients exposed to pollutants, producing ACE2 receptor depletion and compromising host defenses. By presenting an overall view of epidemiological data and molecular mechanisms, this manuscript aims to interpret the possible synergistic effects of both air pollution and COVID-19 on male reproductive function, warning that the spread of SARS-CoV-2 in the fertile years may represent a significant threat to global reproductive health. All of this should be of great concern, especially for men of the age of maximum reproductive capacity, and an important topic of debate for policy makers. Altered environmental conditions, together with the direct and indirect short- and long-term effects of viral infection could cause a worsening of semen quality with important consequences for male fertility, especially in those areas with higher environmental impact.

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.

SARS-CoV-2 vs. human gametes, embryos and cryopreservation

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, is an unprecedented global situation, and all countries have adopted their own measurements to mitigate the spread of the virus in the first as well as in the subsequent waves of infection. All measures, especially in the first wave of the pandemic, were in combination with recommendations provided by professional and scientific organizations. Similar measures were applied to specific procedures, such as the management of infertility, including in vitro fertilization-embryo transfer (IVF-ET) treatments. Although there is no clear scientific evidence yet that the SARS-CoV-2 may exert negative effects on IVF outcome, especially at the early stages, several clinical reports indicate that the virus may impact male fertility through specific receptors presented at the somatic cells of the testis and used by the virus in order to gain entry to the respective cells. Nevertheless, it is not unreasonable to suspect that the virus may affect sperm function as well as oocyte performance directly through specific receptors or indirectly through other signaling pathways. Despite the good practice of IVF laboratory techniques, culture media may also be contaminated during equilibration when airborne virus's particles can contaminate culture media from an already infected embryology area or staff. Furthermore, although there is no clinical evidence, liquid nitrogen could be a route of infection for gametes and embryos when it has been contaminated during production or transportation. Therefore, cryopreservation of gametes and embryos must be virus-free. This communication aims to provide some aspects of the possible impact of the virus on gametes and embryos and how it may affect the cryopreservation procedures.Abbreviations: ACE2: angiotensin- converting enzyme 2; ART: assisted reproductive technology; ASRM: American Society for Reproductive Medicine; CDC: Centers for Disease Control and Prevention; COVID-19: coronavirus disease 2019; ESHRE: European Society of Human Reproduction and Embryology; ET: embryo transfer; FSH: follicle stimulating hormone; IFFS: International Federation of Fertility Societies; IVF: in vitro fertilization; LH: luteinizing hormone; LN: liquid nitrogen; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2; T: testosterone; WHO: World Health Organization.

COVID-19 Pandemic and Male Fertility: Clinical Manifestations and Pathogenic Mechanisms

The novel coronavirus disease-2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been a major public health emergency worldwide with over 118.27-million confirmed COVID-19 cases and 2.62-million deaths recorded, as of March 12, 2021. Although this disease primarily targets lungs, damages in other organs, such as heart, kidney, liver, and testis, may occur. Testis is the cornerstone of male reproduction, while reproductive health is the most valuable resource for continuity of the human race. Given the unique nature of SARS-CoV-2, the mechanisms of its impact on the testes have yet to be fully explored. Notably, coronaviruses have been found to invade target cells through the angiotensin-converting enzyme 2 receptor, which can be found in the respiratory, gastrointestinal, cardiovascular, urinary tract, and reproductive organs, such as testes. Coronavirus studies have suggested that testes might be a potential target for SARS-CoV-2 infection. The first etiopathogenic concept proposed by current hypotheses indicates that the virus can invade testes through the angiotensin-converting enzyme 2 receptor. Next, the activated inflammatory response in the testes, disease-associated fever, and COVID-19 medications might be implicated in testicular alterations. Although evidence regarding the presence of SARS-CoV-2 mRNA in semen remains controversial, this emphasizes the need for researchers to pay closer attention to sexually transmitted diseases and male fertility after recovering from COVID-19. In this review the latest updates regarding COVID-19-associated testicular dysfunction are summarized and possible pathogenic mechanisms are discussed.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2): a Systemic Infection

To date, seven identified coronaviruses (CoVs) have been found to infect humans; of these, three highly pathogenic variants have emerged in the 21st century. The newest member of this group, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first detected at the end of 2019 in Hubei province, China. Since then, this novel coronavirus has spread worldwide, causing a pandemic; the respiratory disease caused by the virus is called coronavirus disease 2019 (COVID-19). The clinical presentation ranges from asymptomatic to mild respiratory tract infections and influenza-like illness to severe disease with accompanying lung injury, multiorgan failure, and death. Although the lungs are believed to be the site at which SARS-CoV-2 replicates, infected patients often report other symptoms, suggesting the involvement of the gastrointestinal tract, heart, cardiovascular system, kidneys, and other organs; therefore, the following question arises: is COVID-19 a respiratory or systemic disease? This review aims to summarize existing data on the replication of SARS-CoV-2 in different tissues in both patients and ex vivo models.

Covid-19: A new global threat for future generations

This is a Letter to the Editor. Please download the PDF or view the article HTML.

Potential impacts of COVID-19 on reproductive health: Scientific findings and social dimension

COVID-19 virus is classified as a respiratory disease that can be mainly transmitted via respiratory droplets, however, there are recently published reports suggested its ability to transmit via sexual intercourse, assisted reproductive technology (ART) treatments, pregnancy, and nursing. Although SARS-CoV-2 mainly attacks respiratory systems, manifestations of multiple organs have been detected. A significant concern was raised about whether COVID-19 may affect female and male reproductive functions. These findings imposed more restrictions on social relationships between individuals even if inside the family, adding more physiologic load. In this context, there is a crucial need to identify the biological and behavioral reproductive risk factors associated with COVID-19 disease. Questions regarding the potential risks of sexual transmission during intercourse and/or application of ART, vertical transmission (throughout pregnancy, delivery, and breastfeeding), the health of pregnant and postpartum women, and fetal or postnatal health problems of neonates/children remain largely unanswered. The contribution of individuals to different social and economic activities depends on the maintenance of good quality life and health. The ongoing COVID-19 pandemic raised on the end of December 2019 has drastically affected different aspects of human wellbeing. The pandemic not only affected the health of individuals, but also negatively affected mental health and social interaction. This review illustrates: a) scientific findings related to the impact of the COVID-19 pandemic on the reproductive process, considering gender, hormonal balance, gonad functions, pregnancy, and ART, b) the sociosexual dimension of COVID-19 disease and precautions that should be taken to avoid infection via sexual transmission or vertical transmission, which may alleviate the fear associated with continuing normal social relationships and economic activities.

COVID-19 and male reproduction: Current research and unknown factors

BACKGROUND

The testes are suspected target organs of SARS-CoV-2. However, the results of studies on the effect of COVID-19 on male reproduction are controversial.

OBJECTIVE

To summarize current research on the effects of COVID-19 on male reproduction.

METHODS

A systematic review of English literature was performed using PubMed and Ovid Embase up to 18 August 2020. Research articles on the presence of SARS-CoV-2 in semen, the effects of the virus on semen parameters and any pathological changes in the testes were evaluated.

RESULTS

Fourteen studies were included in this review. Six of 176 survivors (3.4%) and 1 of 13 decedents (7.7%) in 2 of 12 studies were positive for viral RNA in semen and testicular tissue, respectively. After stratification of patient groups, we found that the virus was detected in the relatively early stage of infection, 6-16 days after disease onset, in semen from survivors. Two of 3 studies reported that some participants had substandard semen quality after COVID-19, and 1 study found that COVID-19 may impair semen quality in a severity-related manner. Pathological analyses showed that injuries to the seminiferous tubule occurred in all decedents (N = 11). Another study found that orchitic and testis fibrin microthrombi occurred in patients with fatal disease (100%, N = 2). Scrotal discomfort of orchiepididymitis or spermatic cord inflammation has also been reported in COVID-19 patients.

CONCLUSION

Current studies suggest that semen is rarely considered a carrier of SARS-CoV-2 genetic material during the infection period but not in the semen of recovered patients. Fatal COVID-19 may cause testicular structure damage without the presence of virus.

Addressing male sexual and reproductive health in the wake of COVID-19 outbreak

PURPOSE

The COVID-19 pandemic, caused by the SARS-CoV-2, represents an unprecedented challenge for healthcare. COVID-19 features a state of hyperinflammation resulting in a "cytokine storm", which leads to severe complications, such as the development of micro-thrombosis and disseminated intravascular coagulation (DIC). Despite isolation measures, the number of affected patients is growing daily: as of June 12th, over 7.5 million cases have been confirmed worldwide, with more than 420,000 global deaths. Over 3.5 million patients have recovered from COVID-19; although this number is increasing by the day, great attention should be directed towards the possible long-term outcomes of the disease. Despite being a trivial matter for patients in intensive care units (ICUs), erectile dysfunction (ED) is a likely consequence of COVID-19 for survivors, and considering the high transmissibility of the infection and the higher contagion rates among elderly men, a worrying phenomenon for a large part of affected patients.

METHODS

A literature research on the possible mechanisms involved in the development of ED in COVID-19 survivors was performed.

RESULTS

Endothelial dysfunction, subclinical hypogonadism, psychological distress and impaired pulmonary hemodynamics all contribute to the potential onset of ED. Additionally, COVID-19 might exacerbate cardiovascular conditions; therefore, further increasing the risk of ED. Testicular function in COVID-19 patients requires careful investigation for the unclear association with testosterone deficiency and the possible consequences for reproductive health. Treatment with phosphodiesterase-5 (PDE5) inhibitors might be beneficial for both COVID-19 and ED.

CONCLUSION

COVID-19 survivors might develop sexual and reproductive health issues. Andrological assessment and tailored treatments should be considered in the follow-up.

The Double Edge Sword of Testosterone's Role in the COVID-19 Pandemic

COVID-19 is a complex disease with a multifaceted set of disturbances involving several mechanisms of health and disease in the human body. Sex hormones, estrogen, and testosterone, seem to play a major role in its pathogenesis, development, spread, severity, and mortalities. Examination of factors such as age, gender, ethnic background, genetic prevalence, and existing co-morbidities, may disclose the mechanisms underlying SARS-CoV-2 infection, morbidity, and mortality, paving the way for COVID-19 amelioration and substantial flattening of the infection curve. In this mini-review, we focus on the role of testosterone through a discussion of the intricate mechanisms of disease development and deterioration. Accumulated evidence suggests that there are links between high level (normal male level) as well as low level (age-related hypogonadism) testosterone in disease progression and expansion, supporting its role as a double-edged sword. Unresolved questions point to the essential need for further targeted studies to substantiate these contrasting mechanisms.

The other side of COVID-19 pandemic: Effects on male fertility

The outbreak of novel coronavirus disease 2019 (COVID-19) has become a major pandemic threat worldwide. According to the existing clinical data, this virus not only causes respiratory diseases and affects the lungs but also induces histopathological or functional changes in various organs like the testis and also the male genital tract. The renin-angiotensin system (RAS), also ACE 2 and TMPRSS2 play an important role in the cellular entry for SARS-CoV-2. Because the male genital system presents high ACE 2 expression, the importance of this pathway increases in COVID-19 cases. As the COVID-19 pandemic has affected the male genital system in direct or indirect ways and showed a negative impact on male reproduction, this paper focuses on the possible mechanisms underlying the damage caused by COVID-19 to the testis and also other components of the male genital tract.

Coronavirus Disease-19 Infection: Implications on Male Fertility and Reproduction

The pandemic caused by Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) has led to several concerns on male fertility. Nowadays, there are numerous unanswered questions, for example: is the virus present or not in the seminal fluid of infected subjects? Could the seminal fluid represent a way of sexual transmission for the virus? Why do men appear to be more susceptible than women? Several studies have been carried out to ascertain the presence of SARS-CoV-2 in the seminal fluid, with contrasting results; the expression of angiotensin-converting enzyme-2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) in the testes and in the male genital tract led to speculation about the possible presence of the virus in the seminal fluid. However, it was found that ACE2 and TMPRSS2, used by the virus to enter host cells, are expressed differently in certain testicle cells (stem germ cells, Leydig and Sertoli cells), yet the testicle cells in which ACE2 and TMPRSS2 molecules are simultaneously expressed are rare. This fact would suggest that the virus is not able to enter testicular cells, that it is not present in the seminal fluid and that it cannot infect male germ cells. However, the direct influence of SARS-CoV-2 on the testes is still to be evaluated, and recent results are very controversial. SARS-CoV-2 could enter the testicle using alternative paths and lead to alterations in testicular functionality. Another plausible consideration is that the COVID-19 disease could also indirectly cause alterations to testicular activity, since the fever and the cytokinic storm generated by the immune system can lead to damage of the testicular activity, consequently compromising male fertility. Although the literature provides controversial evidence, the purpose of this review is to lend a general overview about the state of the art. Despite the lack of studies, it would represent a starting point for further investigation about the effect of this coronavirus on male fertility.

SARS-CoV-2 and the next generations: which impact on reproductive tissues?

Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2) is a severe global pandemic, affecting mostly the respiratory system. Understandably, attention is also being directed towards the urogenital tract. In this work, expression patterns of various host molecules possibly involved in viral entry and replication were investigated in human female and male reproductive systems by inquiring online repositories, including the Human Protein Atlas, GTEx, FANTOM5. Our findings highlight that male reproductive tissues could be targeted by SARS-CoV-2, particularly the testis since it co-expresses the receptor (ACE2) and the protease (TMPRSS) needed for viral entry. We hypothesized that SARS-CoV-2 infection could have repercussions on the fertility status of male individuals Potential infectivity of SARS-CoV-2 in reproductive tissues should be considered in reproductive medicine and management of in vitro fertilization in present and future generations.