Update on COVID-19 and histophysiology of the male reproductive system / Actualización sobre COVID-19 e histofisiología del sistema reproductor masculino

RESUMEN: La reciente pandemia de la COVID-19 ha sacudido a la sociedad teniendo una importante repercusión en el campo de la salud y de la investigación. Dada su relevancia, se han llevado a cabo estudios sobre los efectos del SARS-CoV-2 en la fisiología humana. En concreto, sobre la posible presencia y transmisión del virus a través del sistema reproductor masculino y su posible efecto en el éxito reproductivo. Conocer si la presencia del virus altera los órganos responsables del desarrollo y maduración de las células de la serie espermatogénica podría revelarnos su implicación en la calidad seminal. Por ello, nos planteamos esta revisión, con el fin de analizar las principales evidencias científicas sobre los efectos del SARS-CoV-2 en la histofisiología del sistema reproductor masculino y sobre la capacidad fecundante de los espermatozoides.

SUMMARY: The recent COVID-19 pandemic has shaken up society, having a significant impact on the field of health and research. Given its relevance, studies have been performed on the effects of SARS-CoV-2 on human physiology. In particular, the possible presence and transmission of the virus through the male reproductive system could affect reproductive success. Knowing if the presence of the virus disrupts the organs responsible for the development and maturation of the cell lines involved in spermatogenesis could reveal its implications in sperm quality. For that reason, we proposed this review, in order to analyze the main scientific evidence on the effects of SARS-CoV-2 on the histophysiology of the male reproductive system and sperm fertilizing capacity.

ORF8 protein of SARS-CoV-2 reduces male fertility in mice.

As one of the most rapidly evolving proteins of the genus Betacoronavirus, open reading frames (ORF8's) function and potential pathological consequence in vivo are still obscure. In this study, we show that the secretion of ORF8 is dependent on its N-terminal signal peptide sequence and can be inhibited by reactive oxygen species scavenger and endoplasmic reticulum-Golgi transportation inhibitor in cultured cells. To trace the effect of its possible in vivo secretion, we examined the plasma samples of coronavirus disease 2019 (COVID-19) convalescent patients and found that the patients aged from 40 to 60 had higher antibody titers than those under 40. To explore ORF8's in vivo function, we administered the mice with ORF8 via tail-vein injection to simulate the circulating ORF8 in the patient. Although no apparent difference in body weight, food intake, and vitality was detected between vehicle- and ORF8-treated mice, the latter displayed morphological abnormalities of testes and epididymides, as indicated by the loss of the central ductal lumen accompanied by a decreased fertility in 5-week-old male mice. Furthermore, the analysis of gene expression in the testes between vehicle- and ORF8-treated mice identified a decreased expression of Col1a1, the loss of which is known to be associated with mice's infertility. Although whether our observation in mice could be translated to humans remains unclear, our study provides a potential mouse model that can be used to investigate the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on the human reproductive system.

Sperm quality and absence of SARS-CoV-2 RNA in semen after COVID-19 infection: a prospective, observational study and validation of the SpermCOVID test.

OBJECTIVE: To study the contagiousness of sperm and its influence on fertility after recovery from COVID-19 infection. DESIGN: Prospective cohort study. SETTING: University medical center. PATIENT(S): One hundred twenty Belgian men who had recovered from proven COVID-19 infection. INTERVENTION(S): No intervention was performed. MAIN OUTCOME MEASURE(S): Semen quality was assessed using the World Health Organisation criteria. DNA damage to sperm cells was assessed by quantifying the DNA fragmentation index and the high density stainability. Finally antibodies against SARS-CoV2 spike-1 antigen, nuclear and S1-receptor binding domain were measured by Elisa and chemilumenscent microparticle immunoassays, respectively. RESULT(S): SARS-CoV-2 RNA was not detected in semen during the period shortly after infection nor at a later time. Mean progressive motility was reduced in 60% of men tested shortly (<1 month) after COVID-19 infection, 37% of men tested 1 to 2 months after COVID-19 infection, and 28% of men tested >2 months after COVID-19 infection. Mean sperm count was reduced in 37% of men tested shortly (<1 month) after COVID-19 infection, 29% of men tested 1 to 2 months after COVID-19 infection, and 6% of men tested >2 months after COVID-19 infection. The severity of COVID-19 infection and the presence of fever were not correlated with sperm characteristics, but there were strong correlations between sperm abnormalities and the titers of SARS-CoV-2 IgG antibody against spike 1 and the receptor- binding domain of spike 1, but not against nucleotide, in serum. High levels of antisperm antibodies developed in three men (2.5%). CONCLUSION(S): Semen is not infectious with SARS-CoV-2 at 1 week or more after COVID-19 infection (mean, 53 days). However, couples with a desire for pregnancy should be warned that sperm quality after COVID-19 infection can be suboptimal. The estimated recovery time is 3 months, but further follow-up studies are under way to confirm this and to determine if permanent damage occurred in a minority of men.

Understanding the cross-talk between mediators of infertility and COVID-19.

COVID-19 is the ongoing health emergency affecting individuals of all ages around the globe. Initially, the infection was reported to affect pulmonary structures. However, recent studies have delineated the impacts of COVID-19 on the reproductive system of both men and women. Hence, the present review aims to shed light on the distribution of SARS-CoV-2 entry factors in various reproductive organs. In addition, impacts of COVID-19 mediators like disrupted renin angiotensin system, oxidative stress, cytokine storm, fever, and the mental stress on reproductive physiology have also been discussed. For the present study, various keywords were used to search literature on PubMed, ScienceDirect, and Google Scholar databases. Articles were screened for relevancy and were studied in detail for qualitative synthesis of the review. Through our literature review, we found a multitude of effects of COVID-19 mediators on reproductive systems. Studies reported expression of receptors like ACE-2, TMPRSS2, and CD147 in the testes, epididymis, prostrate, seminal vesicles, and ovarian follicles. These proteins are known to serve as major SARS-CoV-2 entry factors. The expression of lysosomal cathepsins (CTSB/CTSL) and/ neuropilin-1 (NRP-1) are also evident in the testes, epididymis, seminal vesicles, fallopian tube, cervix, and endometrium. The binding of viral spike protein with ACE-2 was found to alter the renin-angiotensin cascade, which could invite additional infertility problems. Furthermore, COVID-19 mediated cytokine storm, oxidative stress, and elevated body temperature could be detrimental to gametogenesis, steroidogenesis, and reproductive cycles in patients. Finally, social isolation, confinement, and job insecurities have fueled mental stress and frustration that might promote glucocorticoid-mediated subnormal sperm quality in men and higher risk of miscarriage in women. Hence, the influence of COVID-19 on the alteration of reproductive health and fertility is quite apparent.

Does COVID-19 Worsen the Semen Parameters? Early Results of a Tertiary Healthcare Center.

INTRODUCTION: The coronavirus disease 2019 (COVID-19) is a global pandemic which may affect multiple organs and systems including testes and disrupt the gonadal functions. The current study aimed to evaluate the effect of COVID-19 on the semen parameters and sex-related hormone levels in infertile men. METHODS: The study included 21 patients who were evaluated in Ankara City Hospital, Andrology Clinic, for male infertility and have had the diagnosis of COVID-19. All the patients were evaluated in terms of semen parameters. The follicle-stimulating hormone, luteinizing hormone, and testosterone (T) levels were also evaluated in 8 of the patients. The results were presented through 2 dependent group analyses, based on the data of the patients collected before and after the diagnosis of COVID-19. RESULTS: None of the patients needed to be hospitalized at any time through the course of COVID-19. There was a significant decrease in semen volume, percentage of total motility, percentage of progressive motility, and normal sperm morphology after COVID-19 (3 [1-8] vs. 2.5 [1.5-5], p = 0.005; 48.6 ± 22.1 vs. 34.7 ± 20.7, p = 0.001; 35.1 ± 21.7 vs. 21.8 ± 15.9, p < 0.001; 6 [3-24] vs. 5 [3-18], p = 0.015; respectively). There was also a significant decline in T level of the patients after the diagnosis of COVID-19 (350.1 ± 115.5 vs. 289.8 ± 103.3, p = 0.009). CONCLUSION: COVID-19 may have unfavorable effects on the gonadal functions and may lead to further deterioration of the semen parameters in infertile men, which should be considered through the evaluation for infertility.

In Silico Identification of miRNA-lncRNA Interactions in Male Reproductive Disorder Associated with COVID-19 Infection.

Coronavirus disease 2019 (COVID-19), a global pandemic, is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Angiotensin-converting enzyme 2 (ACE2) is the receptor for SARS-CoV-2 and transmembrane serine protease 2 (TMPRSS2) facilitates ACE2-mediated virus entry. Moreover, the expression of ACE2 in the testes of infertile men is higher than normal, which indicates that infertile men may be susceptible to be infected and SARS-CoV-2 may cause reproductive disorder through the pathway induced by ACE2 and TMPRSS2. Little is known about the pathway regulation of ACE2 and TMPRSS2 expression in male reproductive disorder. Since the regulation of gene expression is mediated by microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) at the post-transcriptional level, the aim of this study was to analyze the dysregulated miRNA-lncRNA interactions of ACE2 and TMPRSS2 in male reproductive disorder. Using bioinformatics analysis, we speculate that the predicted miRNAs including miR-125a-5p, miR-125b-5p, miR-574-5p, and miR-936 as regulators of ACE2 and miR-204-5p as a modulator of TMPRSS2 are associated with male infertility. The lncRNAs with a tissue-specific expression for testis including GRM7-AS3, ARHGAP26-AS1, BSN-AS1, KRBOX1-AS1, CACNA1C-IT3, AC012361.1, FGF14-IT1, AC012494.1, and GS1-24F4.2 were predicted. The identified miRNAs and lncRNAs are proposed as potential biomarkers to study the possible association between COVID-19 and male infertility. This study encourages further studies of miRNA-lncRNA interactions to explain the molecular mechanisms of male infertility in COVID-19 patients.

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.

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.

COVID-19 and male reproductive function: a prospective, longitudinal cohort study.

The existing evidence suggests that the human reproductive system may be potentially vulnerable to COVID-19 infection. However, little is known about the virus-host interaction of COVID-19 in sperm cells. We are the first to address the connection between changes in multiple seminal biomarkers and reproductive function in male patients recovering from COVID-19. In a prospective longitudinal cohort study, seminal ACE2 activity, markers of inflammation and oxidative stress, apoptotic variables, and semen quality parameters were evaluated at 10-day intervals for a maximum follow-up time of 60 days among male patients with laboratory-confirmed COVID-19 (n = 84) and healthy controls (CON; n = 105). At the baseline and the subsequent follow-ups, the COVID-19 group revealed significantly higher levels of seminal plasma ACE2 enzymatic activity, IL-1ß, IL-6, IL-8, IL-10, TGF-ß, TNF-α, IFN-α, IFN-γ, ROS, caspase-8, caspase-9, and caspase-3 activity as well as lower levels of SOD activity than those in the CON group (P < 0.05). These perturbations tended to persist over time and were correlated with significant impairments in semen volume, progressive motility, sperm morphology, sperm concentration, and the number of spermatozoa. We provide the direct experimental evidence that the male reproductive system could be targeted and damaged by the COVID-19 infection. These findings go beyond our current understanding of the disease, suggesting that the reproductive function of the patients recovering from the disease should be precisely followed and evaluated to detect and avoid more serious reproductive problems in the future, as they may develop a transient state of male subfertility like those with oligoasthenoteratozoospermia.

Review of COVID-19 and male genital tract.

COVID-19 pandemic leads to health challenges globally, and its diverse aspects need to be uncovered. Multi-organ injuries have been reported by describing potential SARS-CoV-2 entrance routes: ACE2 and TMPRSS2. Since these cell surface receptors' expression has been disclosed within the male reproductive system, its susceptibility to being infected by SARS-CoV-2 has been summarised through this literature review. Expression of ACE2 and TMPRSS2 at RNA or protein level has been reported across various investigations indicates that the male genitalia potentially is vulnerable to SARS-CoV-2 infection. Presence of SARS-CoV-2 within semen samples and following direct viral damage, secondary inflammatory response causing orchitis or testicular discomfort and finally the amount of viral load leading testicular damage and immune response activation are among probable underlying mechanisms. Therefore, genital examination and laboratory tests should be considered to address the male reproductive tract complications and fertility issues.

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.

Evaluating the impact of COVID-19 on male reproduction.

Invasion or damage of the male reproductive system is one of the reported outcomes of viral infection. Current studies have documented that SARS-CoV-2, which causes COVID-19, can damage the male reproductive system in large part by inflammatory damage caused by a cytokine storm. However, whether SARS-CoV-2 can infect the human testis directly and enter semen is controversial. Other adverse effects of SARS-CoV-2 on male reproduction are also of concern and require comprehensive evaluation. Here, we analyze the invasiveness of SARS-CoV-2 in the testis and examine reported mechanisms by which SARS-CoV-2 interferes with male reproduction. Long-term implications of SARS-CoV-2 infection on male reproduction are also discussed. It should be emphasized that although COVID-19 may induce testicular damage, a substantial decrease in male reproductive capacity awaits clinical evidence. We propose that there is an urgent need to track male COVID-19 patients during their recovery. The development of suitable experimental models, including human reproductive organoids, will be valuable to further investigate the viral impact on reproduction for current and future pandemics.

Testicular Atrophy and Hypothalamic Pathology in COVID-19: Possibility of the Incidence of Male Infertility and HPG Axis Abnormalities.

Coronavirus disease 2019 (COVID-19), which resulted from the pandemic outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causes a massive inflammatory cytokine storm leading to multi-organ damage including that of the brain and testes. While the lungs, heart, and brain are identified as the main targets of SARS-CoV-2-mediated pathogenesis, reports on its testicular infections have been a subject of debate. The brain and testes are physiologically synchronized by the action of gonadotropins and sex steroid hormones. Though the evidence for the presence of the viral particles in the testicular biopsies and semen samples from COVID-19 patients are highly limited, the occurrence of testicular pathology due to abrupt inflammatory responses and hyperthermia has incresingly been evident. The reduced level of testosterone production in COVID-19 is associated with altered secretion of gonadotropins. Moreover, hypothalamic pathology which results from SARS-CoV-2 infection of the brain is also evident in COVID-19 cases. This article revisits and supports the key reports on testicular abnormalities and pathological signatures in the hypothalamus of COVID-19 patients and emphasizes that testicular pathology resulting from inflammation and oxidative stress might lead to infertility in a significant portion of COVID-19 survivors. Further investigations are required to monitor the reproductive health parameters and HPG axis abnormalities related to secondary pathological complications in COVID-19 patients and survivors.

Investigation of SARS-CoV-2 in semen samples and the effects of COVID-19 on male sexual health by using semen analysis and serum male hormone profile: A cross-sectional, pilot study.

The study investigated whether there is a male reproductive system coronavirus disease-2019 (COVID-19) phenomenon. Thirty participants who met the inclusion criteria were enrolled in the study between April and May 2020. The participants were assigned in one of the three groups including COVID-19 patients before and after treatment, and controls. Presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within the semen samples was investigated. Additionally, participant's demographics, semen parameters and serum sex hormone levels were compared between the groups. SARS-CoV-2 was not detected within the semen samples. Sperm morphology and serum sex hormone levels were significantly different between the groups. In the post hoc analysis, sperm morphology was significantly lower in the COVID-19 patients. Patients before treatment had significantly lower serum FSH, LH and T levels than controls. However, patients after treatment had similar serum FSH, LH and T levels with controls and patients before treatment. In our opinion, COVID-19 and its treatment had no specific deteriorative effect on male sexual health at a short-time period. In the patients before treatment, decreased serum of T, FSH and LH levels was consistent with acute patient stress due to COVID-19. Similarly, it seems that decreased sperm morphology was associated with the acute fever.

SARS-COV-2 (Covid-19) and male fertility: Where are we?

Severe acute respiratory syndrome coronavirus 2 (SARS-COV-2), a single-stranded RNA virus, was found to be the causal agent of the disease called coronavirus disease. During December 2019, China informed the World Health Organization (WHO) of an outbreak of cases of pneumonia of unknown etiology, which caused severe-acute respiratory distress. The disease was termed coronavirus disease 2019 (Covid-19). Due to alarming levels of spread and severity, on the 11th of March 2020, the WHO declared the outbreak as a global pandemic. As of September 14, 2020, more than 29 million cases have been reported, with over 900,000 deaths globally. Since the outbreak, although not conclusive, discoveries have been made regarding the understanding of the epidemiology, etiology, clinical features, clinical treatment, and prevention of the disease. SARS-COV-2 has been detected in saliva, respiratory fluids, blood, urine, and faeces. Findings are however controversial regarding its presence in the semen or the testis. Hence, this review aimed to further analyse the literature concerning (i) the effects of previously identified human coronaviruses on male fertility (ii) the impact of Covid-19 on male fertility and (iii) the implication for general health in terms of infection and transmission.

The role of Interleukin-4 in COVID-19 associated male infertility - A hypothesis.

COVID-19 is a present-day complex pandemic infection with unpredictable levels of morbidity and mortality in various global populations. COVID-19 is associated with the different comorbidities with its change in biological function such as causing heart dysfunction via deregulating ACE-2 receptor, gastrointestinal risk via causing vomiting, diarrhea, and abdominal pain, chronic kidney disease via proteinuria and hematuria, diabetes mellitus, liver injury via increasing ALT, AST and bilirubin level, lung injury, CNS risk, ocular risk, and cancer risk. In this, we are focused on the COVID-19 connected with male infertility. Some of the studies show that the patients of COVID-19 are associated with impaired spermatogenesis. Impaired spermatogenesis via COVID-19 decreases the level of testosterone by disturbing cytokines such as TNF-α, IL-4, IL-6, and IL-12 and further, attenuates the sperm count. COVID-19 is causing inflammation via TNF-α and interferons. IL-4 plays an eminent role in the activation of the JAK-STAT pathway and leads to the disturbing pro-inflammatory cytokine as well as further cause's male infertility. Th2 activates the IL-4 through IgG and IgE and mediates apoptosis with the triggering of STAT signaling. The activated STAT signaling augments Batf/Irf4, and the Bach2/Batf pathway. On the other hand, SARS-CoV-2 is activating the level of Th2 cells. So, we hypothesized that the augmented Th2 cells would disturb the level of IL-4, JAK-STAT signaling, Batf/Irf4, and Bach2/Batf pathway. The disturbed IL-4 decreases the level of the ACE-2 with the inflammation. This further leads to male infertility in COVID-19 patients. So, in this hypothesis, we focused on the role of IL-4 in COVID-19 patients associated with male infertility via Th2 cells and JAK-STAT signaling.

Mechanisms by Which SARS-CoV-2 May Impact Male Fertility.

The COVID-19 pandemic is unlike anything we have experienced in over a century. In the USA, waves of COVID-19 have migrated from the Northeast to the Sun Belt to the Midwest over the past year. Compared with females, males are more susceptible to SARS-CoV-2 infection, have more severe COVID-19 disease, and have higher death rates. In many countries, men are consistently more likely to die by a factor of almost 2. This article describes some of the mechanisms by which COVID-19 may be associated with male infertility, as discussed by Dutta and Sengupta.

Coronavirus: A possible cause of reduced male fertility.

In lately December 2019, a novel coronavirus (SARS-CoV-2) outbreak occurred in Wuhan, PR China. It is a high contagious virus that has threatened human health worldwide. SARS-CoV-2 infection, termed COVID-19, causes rapidly developing lung lesions that can lead to multiple organ failure in a short period. Whenever a novel virus emerges, reproductive risk assessments should be performed after infection. In this review, we show that male fertility might be damaged by coronavirus associated with (i) direct cytopathic effects derived from viral replication and viral dissemination in the testis; and (ii) indirect damage to male fertility derived from immunopathology. In this review, we briefly describe the impaired fertility of humans and animals infected with coronaviruses to deduce the impact of the new coronavirus on male fertility. Together with information related to other coronaviruses, we extrapolate this knowledge to the new coronavirus SARS-CoV-2, which may have a significant impact on our understanding of the pathophysiology of this new virus.