COVID-19 disrupts spermatogenesis through the oxidative stress pathway following induction of apoptosis

Quantitative Proteomics of COVID-19 Recovered Patients Identifies Long-Term Changes in Sperm Proteins Leading to Cellular Stress in Spermatozoa

Following an initial recovery, COVID-19 survivors struggle with a spectrum of persistent medical complications, including fatigue, breathlessness, weight loss, hair loss, and attention deficits. Additionally, there is growing evidence of adverse effects of COVID-19 on the male reproductive system. This investigation seeks to understand the long-term ramifications on male fertility by examining hormonal profiles, semen parameters, and sperm proteome of recovered COVID-19 patients compared to controls. The serum hormone profiles between the two groups showed minimal variations except for prolactin, cortisol, and testosterone levels. Testosterone levels were slightly lower, while prolactin and cortisol were elevated in COVID-19 cases compared to controls. Though semen parameters exhibited no significant disparities between the COVID-19 and control groups, quantitative proteomics analysis revealed changes in sperm proteins. It identified 190 differentially expressed proteins, of which 161 were upregulated and 29 downregulated in COVID-19 cases. Western blotting analysis validated the differential expression of serpin B4 and calpain 2. Bioinformatics analysis signifies cellular stress in the spermatozoa of COVID-19 recovered patients and thus, SOD and MDA levels in semen were measured. MDA levels were found to be significantly elevated, indicating lipid peroxidation in COVID-19 samples. While the effects of COVID-19 on semen parameters may exhibit a potential for reversal within a short duration, the alterations it inflicts on sperm proteome are persisting consequences on male fertility. This study paves the path for further research and emphasizes the significance of comprehending the complex molecular processes underlying the long-term consequences of COVID-19 on male reproductive health.

Impact of COVID-19 on testicular function: a systematic review and meta-analysis

INTRODUCTION

Studies investigating the effects of SARS-CoV-2 on male reproductive function are few and heterogeneous, and results are often conflicting. This systematic review and meta-analysis was carried out on studies conducted in men with active or anamnestic SARS-CoV-2 infection to evaluate its consequences on the male sex hormone profile and semen parameters.

MATERIALS AND METHOD

This meta-analysis follows the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) protocols. PubMed, Scopus, Cochrane, and Embase databases were searched to identify relevant studies. We originally selected 3553 articles. After the eligibility phase, 16 articles met our inclusion criteria encompassing 11 case-control studies and 5 cohort studies (2 prospective and 3 retrospective studies). We performed the quantitative analysis with Comprehensive Meta-Analysis Software. Cochran-Q and heterogeneity (I2) indexes were used to assess statistical heterogeneity. Sensitivity analysis and publication bias tests were also performed.

RESULTS

Overall, 1250 patients with active or recent (up to 80 days before) COVID-19 infection and 1232 matched healthy controls were included. Sperm concentration, total sperm count, and total motility were significantly lower in patients compared with controls. Patients also showed lower levels of total testosterone and follicle-stimulating hormone, and higher levels of luteinizing hormone, 17β-estradiol, and prolactin compared with healthy controls. None of the included studies found the presence of SARS-CoV-2 mRNA in the semen of infected patients.

CONCLUSION

The present systematic review and meta-analysis suggests the presence of an association between SARS-CoV-2 infection and primary testicular damage manifested with a picture of altered steroidogenesis and worsening spermatogenesis. The absence of the virus in the seminal fluid indicates a low possibility of sexual transmission of the infection to partners and offspring. However, our findings mostly show short-term follow-up, while few studies have considered the long-term consequences of the viral infection, thus further studies are needed to evaluate the long-term consequences on male reproductive health.

Integrative Assessment of Seminal Plasma Biomarkers: A Narrative Review Bridging the Gap between Infertility Research and Clinical Practice

Infertility represents a significant global health challenge impacting millions of couples worldwide. Approximately half of all infertile couples exhibit compromised semen quality, indicative of diminished male fertility. While the diagnosis of male infertility traditionally relies on semen analysis, its limitations in providing a comprehensive assessment of male reproductive health have spurred efforts to identify novel biomarkers. Seminal plasma, a complex fluid containing proteins, lipids, and metabolites, has emerged as a rich source of such indicators. Reproduction depends heavily on seminal plasma, the primary transporter of chemicals from male reproductive glands. It provides a non-invasive sample for urogenital diagnostics and has demonstrated potential in the identification of biomarkers linked to illnesses of the male reproductive system. The abundance of seminal proteins has enabled a deeper understanding of their biological functions, origins, and differential expression in various conditions associated with male infertility, including azoospermia, asthenozoospermia, oligozoospermia, teratozoospermia, among others. The true prevalence of male infertility is understated due to the limitations of the current diagnostic techniques. This review critically evaluates the current landscape of seminal plasma biomarkers and their utility in assessing male infertility. Βy bridging the gap between research and clinical practice, the integrative assessment of seminal plasma biomarkers offers a multimodal approach to comprehensively evaluate male infertility.

Male reproductive function before and after the adjustment of the COVID-19 prevention policy: a multicenter study in China

At the end of 2022, the adjustment of the coronavirus disease 2019 (COVID-19) pandemic control policy in China resulted in a large-scale increase in public infection. To compare the fertility parameters of male patients before and after the adjustments of the COVID-19 pandemic control policy in China, we collected data on patients' medical histories and laboratory examinations on their first visits between June 2022 and March 2023 in five different hospitals. Data were divided into five groups according to the timeline of the policy adjustment. The data we collected from male patients included semen quality and serum reproductive hormone levels, and intergroup comparisons were made using the Mann-Whitney U and Chi-square tests. In total, 16 784 cases underwent regular semen analysis, 11 180 had sperm morphology assessments, and 7200 had reproductive hormone analyses. The data showed declining trends in semen volume, sperm motility, and the progressive sperm motility rate after the policy adjustment. Subgroup comparison revealed an initial decrease and gradual recovery in progressive motility rate. Sperm morphology analysis showed increased neck and tail abnormalities after the policy adjustment. No significant change in hormone levels was observed. Following the adjustment of the COVID-19 prevention policy in China, a decline in sperm motility and morphology was observed. This trend may gradually recover over 2 months. After the policy adjustment, reproductive hormone levels were relatively stable throughout, except for an increase in luteinizing hormone (LH). These changes in semen parameters suggest that the policy adjustment had a short- to medium-term impact on male reproductive function.

Exosome Therapy and Photobiomodulation Therapy Regulate mi-RNA 21, 155 Expressions, Nucleus Acetylation and Glutathione in a Polycystic Ovary Oocyte: An In Vitro Study

Introduction: Polycystic ovary syndrome (PCOS) is a complex condition that can have various symptoms and complications, one of which is infertility. Dysregulation of miRNA has been associated with the pathogenesis of numerous illnesses such as PCOS. In this study, we evaluated the effect of photobiomodulation therapy (PBMT) and exosome therapy (EXO) on the regulation of miRNA and nucleus acetylation in a PCOS oocyte. Methods: In this research, 36 oocytes divided into three groups: control, EXO, and PBM (Wavelength of 640 nm). Subsequently, in-vitro maturation (IVM) was evaluated. Real-time PCR was used to evaluate miRNA-21,16,19,24,30,106,155 and GAPDH. Afterward, oocyte glutathione (GSH) and nucleus acetylation were measured by H4K12. Results: The expression of the miR-16, miRNA-19, miRNA-24, miRNA-106 and miRNA-155 genes in the EXO and PBMT groups was significantly down-regulated in comparison to the control group, but the expression of miRNA-21 and miR-30 significantly increased in the EXO and PBMT groups in comparison to the control group. The EXO and PBMT significantly increased GSH and nucleus acetylation (P<0.0001). Conclusion: The results of this study showed that the use of EXO and PBMT can improve GSH and nucleus acetylation in the PCOS oocyte and also change the expression of miRNAs.

Therapeutic Effects of Exosome Therapy and Photobiomodulation Therapy on the Spermatogenesis Arrest in Male Mice After Scrotum Hyperthermia

Introduction: In men, several factors cause infertility, among which we can mention damage to sperm due to high temperature. So far, various treatments have been proposed for it, but they have not been highly effective. The current study aimed to evaluate the effect of exosome therapy (EXO) and photobiomodulation therapy (PBMT) on spermatogenesis arrest in male mice after scrotum hyperthermia. Methods: In this experimental study, the animals were divided into four groups: control, scrotal hyperthermia, scrotal hyperthermia+EXO (100 μL/d) (mice were treated for 30 days), scrotal hyperthermia+PBMT (laser of 0.03 J/cm2 for 30 seconds/for 30 days). Hyperthermia was induced by exposure to the temperature of 43 °C for 20 minute every day for 5 times. After 6 weeks, the animals were sacrificed. Results: The treated groups showed a significant increase in sperm parameters, as compared to the hyperthermic groups. Moreover, these favorable effects were observed in relation to the volume of testicular tissue, the number of germ cells, Leydig cells and Sertoli cells, and the level of testosterone. Research on antioxidants showed a significant reduction in oxidized glutathione (GSSG) and reactive oxygen species (ROS) in the treatment groups in comparison to the hyperthermia group (P<0.001). Also, there has been a significant increase in the amount of hydrogen peroxide enzyme observed in the hyperthermia group as opposed to the treatment group (P<0.001). Conclusion: These findings show that EXO and PBMT can improve spermatogenesis caused by hyperthermia, reduce ROS and GSSG, and increase glutathione (GSH) and sperm quality.

Transcriptome and proteome analyses reveal the mechanisms involved in polystyrene nanoplastics disrupt spermatogenesis in mice

Nanoplastics have been demonstrated to be reproductively toxic to mammals. However, the mechanisms of nanoplastics induce reproductive damage in mammals, especially their effects on spermatogenesis, remain elusive. Herein, we explored the effects and underlying mechanisms of polystyrene nanoplastics (PS-NPs) on the testicular development of male mice after 28 days of exposure, representing the first systematic study of PS-NPs-induced male reproductive injury by integrating histomorphology, transcriptomics and proteomics. PS-NPs decreased the sperm concentration, sperm motility, and disrupted the structure of the seminiferous tubules of the mice. Besides, transcriptome and proteome analyses revealed that PS-NPs disrupted spermatogenesis by inhibiting the transcription of Prm3/Tnp1/Aurkc/Mea1/Mettl14 and the expression of Pmfbp1/Ggn/Fsip2. Furthermore, PS-NPs enabled Hsd3b5 protein expression to reduce dihydrotestosterone levels, and affected sperm flagellar assembly by decreasing the expression of Dnah8/Tekt5/Rsph6a. Moreover, PS-NPs induced testicular cell apoptosis by up-regulating the expression of cathepsins (B/F/H). In addition, PS-NPs destroyed tight junctions by reducing the expression of the Claudin family (3/5/15). In conclusion, PS-NPs can disrupt spermatogenesis by altering the expression patterns of transcriptome and proteome, inducing testicular cell apoptosis and destroying tight junctions.

Does COVID-19 affect sperm quality in males? the answer may be yes, but only temporarily

BACKGROUND

The Corona Virus Disease 2019 (COVID-19) pandemic has raised concerns regarding its potential impact on male reproductive health. However, the impact of COVID-19 on sperm quality remains uncertain. This retrospective study aimed to investigate the short-term and relatively long-term effects of COVID-19 infection on sperm quality.

METHODS

A total of 85 males with fertility requirements, who underwent semen evaluation at Guilin People's Hospital between June 2022 and July 2023, were included in the study. Changes in semen parameters were analyzed across three specific timeframes: within 6 months before COVID-19 infection, within 3 months after COVID-19 infection, and 3-6 months after COVID-19 recovery.

RESULTS

The results revealed that the sperm concentration and total sperm number were significantly lower after infection compared to before, while in the recovery period, the sperm concentration, total sperm count, progressive motility, and normal morphology significantly increased. Comparing the three periods, the most significant difference was observed in sperm concentration, which exhibited a significant decrease after infection but returned to normal levels after recovery from COVID-19.

CONCLUSIONS

These findings suggest that COVID-19 may exert some impact on sperm quality, particularly evidenced by decreased sperm concentration post-infection. Fortunately, these effects on semen parameters appear to be temporary, with gradual restoration of semen parameters within 3-6 months after recovery. However, further research is needed to explore the underlying mechanisms and long-term implications of these observed changes in semen parameters.

SARS-CoV-2 infection (COVID-19) and male fertility: Something we should be worried about?

As of 2021, roughly 5 million deaths were linked to SARS-CoV-2 infection based on World Health Organization estimates. The pandemic takes its staggering death toll, severely affecting the healthcare systems and leading to detrimental implications globally. While the severe impact on the respiratory system is well-established, the exact effect on male reproduction is still largely uncharted territory. When it comes to gender, men appear more vulnerable compared to women. Increasing evidence suggests that COVID-19 adversely affects spermatogenesis and hormonal balance in diverse ways. Semen parameters seem to be compromised at least temporarily, while long-term worsening needs to be clarified in studies with extended follow-up. For the time being, no data support the adverse effect of COVID-19 vaccines on a male's reproductive health. In the present article, we examine the available literature and briefly discuss the impact of the virus on reproduction and fertility. We further provide a comprehensive overview of the current status of vaccination and its potential effect on male fertility. Ultimately, we address the need for future well-designed large-scale trials before drawing definite conclusions on the exact impact of the virus on a male's fecundity.

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.

Comparison of sperm parameters and DNA fragmentation index between infertile men with infection and vaccines of COVID-19

Several preventive measures, including vaccination, have been implemented owing to the severe global effect of coronavirus disease 2019 (COVID-19), but there is still limited evidence in the effect of this disease and vaccination against it on male fertility. Therefore, this study is to compare sperm parameters of infertile patients with or without COVID-19 infection and the effect of COVID-19 vaccine types on them. Semen samples of infertile patients were collected consecutively at Universitas Indonesia - Cipto Mangunkusumo Hospital (Jakarta, Indonesia). COVID-19 was diagnosed by rapid antigen or polymerase chain reaction (PCR) tests. Vaccination was performed with three types of vaccine, namely inactivated viral vaccine, messenger RNA (mRNA) vaccine, and viral vector vaccine. Spermatozoa were then analyzed on the World Health Organization recommendations, and DNA fragmentation was assayed with the sperm chromatin dispersion kit. The results showed that the COVID-19 group experienced a significant decrease in sperm concentration and progressive motility (both P < 0.05), but there was no significant change in morphology or sperm DNA fragmentation index (DFI; both P > 0.05). The viral vector vaccine caused a decrease in morphology as well as an increase in DFI compared with the control (both P < 0.05), meanwhile results for those who were vaccinated with the inactivated and mRNA types were not significant compared with the control (both P > 0.05). We conclude that COVID-19 has negative effects on sperm parametes and sperm DNA fragmentation, and we found that the viral vector vaccines affect sperm parameter values and DNA fragmentation negatively. Further studies with a larger population and longer follow-up are needed to confirm the results.

SARS-CoV-2 and male infertility: from short- to long-term impacts

PURPOSE

The coronavirus 2019 (COVID-19) pandemic-caused by a new type of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-has posed severe impacts on public health worldwide and has resulted in a total of > 6 million deaths. Notably, male patients developed more complications and had mortality rates ~ 77% higher than those of female patients. The extensive expression of the SARS-CoV-2 receptor and related proteins in the male reproductive tract and the association of serum testosterone levels with viral entry and infection have brought attention to COVID-19's effects on male fertility.

METHODS

The peer-reviewed articles and reviews were obtained by searching for the keywords SARS-CoV-2, COVID-19, endocrine, spermatogenesis, epididymis, prostate, and vaccine in the databases of PubMed, Web of Science and Google Scholar from 2020-2022.

RESULTS

This review summarizes the effects of COVID-19 on the male reproductive system and investigates the impact of various types of SARS-CoV-2 vaccines on male reproductive health. We also present the underlying mechanisms by which SARS-CoV-2 affects male reproduction and discuss the potentially harmful effects of asymptomatic infections, as well as the long-term impact of COVID-19 on male reproductive health.

CONCLUSION

COVID-19 disrupted the HPG axis, which had negative impacts on spermatogenesis and the epididymis, albeit further investigations need to be performed. The development of vaccines against various SARS-CoV-2 variations is important to lower infection rates and long-term COVID risks.

COVID-19 and Male Infertility: Is There a Role for Antioxidants?

Coronavirus disease 19 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), jeopardizes male fertility because of the vulnerability of the male reproductive system, especially the testes. This study evaluates the effects of the virus on testicular function and examines the potential role of antioxidants in mitigating the damage caused by oxidative stress (OS). A comprehensive PubMed search examined exocrine and endocrine testicular function alteration, the interplay between OS and COVID-19-induced defects, and the potential benefit of antioxidants. Although the virus is rarely directly detectable in sperm and testicular tissue, semen quality and hormonal balance are affected in patients, with some changes persisting throughout a spermatogenesis cycle. Testicular pathology in deceased patients shows defects in spermatogenesis, vascular changes, and inflammation. Acute primary hypogonadism is observed mainly in severely infected cases. Elevated OS and sperm DNA fragmentation markers suggest redox imbalance as a possible mechanism behind the fertility changes. COVID-19 vaccines appear to be safe for male fertility, but the efficacy of antioxidants to improve sperm quality after infection remains unproven due to limited research. Given the limited and inconclusive evidence, careful evaluation of men recovering from COVID-19 seeking fertility improvement is strongly recommended.

The role of oxidative stress in the pathogenesis of infections with coronaviruses

Coronaviruses can cause serious respiratory tract infections and may also impact other end organs such as the central nervous system, the lung and the heart. The coronavirus disease 2019 (COVID-19) has had a devastating impact on humanity. Understanding the mechanisms that contribute to the pathogenesis of coronavirus infections, will set the foundation for development of new treatments to attenuate the impact of infections with coronaviruses on host cells and tissues. During infection of host cells, coronaviruses trigger an imbalance between increased production of reactive oxygen species (ROS) and reduced antioxidant host responses that leads to increased redox stress. Subsequently, increased redox stress contributes to reduced antiviral host responses and increased virus-induced inflammation and apoptosis that ultimately drive cell and tissue damage and end organ disease. However, there is limited understanding how different coronaviruses including SARS-CoV-2, manipulate cellular machinery that drives redox responses. This review aims to elucidate the redox mechanisms involved in the replication of coronaviruses and associated inflammation, apoptotic pathways, autoimmunity, vascular dysfunction and tissue damage that collectively contribute to multiorgan damage.

A review on human reproductive systems encountering with the severe acute respiratory syndrome coronavirus 2 infection

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) is the leading cause of the new deadly pneumonia named coronavirus disease 2019 (COVID-19) pandemic. This pathogen has different co-receptors on various tissues, resulting in vast pathophysiological circumstances. Here, we present a comprehensive narrative review focusing on the impact of SARS-CoV2 on human reproduction. Evidence-based literature revealed inconsistent results for this virus in the reproductive organs of patients with COVID-19, even in the critical phase. Conversely, numerous satisfactory data represented those different reproductive activities, from gametogenesis to pregnancy, can be targeted by SARS-CoV2. The severity of COVID-19 depends on the differential expression of the host cellular components required to enter SARS-CoV2. The cytokine storm and oxidative stress coming out during COVID-19 are associated with complications in reproductive endocrinopathies. Men are naturally more susceptible to COVID-19, especially accompanied by orchitis and varicocele. Synergistically the interaction of SARS-CoV2 and female reproductive failures (polycystic ovary syndrome and endometriosis) increases the susceptibility to COVID-19. Thus, pharmaceutical interventions that ameliorate the complications in individuals with reproductive disorders can be helpful to achieve good outcomes in assisted reproductive techniques. Soon, an increase in the infertility rate will likely be an overall impact of SARS-CoV2 in patients who recovered from COVID-19.

Ubiquitination of SARS-CoV-2 ORF7a Prevents Cell Death Induced by Recruiting BclXL To Activate ER Stress

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19), which has emerged in the last 2 years. The accessory protein ORF7a has been proposed as an immunomodulating factor that can cause dramatic inflammatory responses, but it is unknown how ORF7a interacts with host cells. We show that ORF7a induces cell apoptosis by recruiting the prosurvival factor BclXL to the endoplasmic reticulum (ER) via the exposed C-terminal residues Lys117 and Lys119. Simultaneously, ORF7a activates ER stress via the PERK-elF2α-CHOP pathway and inhibits the expression of endogenous BclXL, resulting in enhanced cell apoptosis. Ubiquitination of ORF7a interrupts the interaction with BclXL in the ER and weakens the activation of ER stress, which to some extent rescues the cells. Our work demonstrates that SARS-CoV-2 ORF7a hires antiapoptosis protein and aggregates on the ER, resulting in ER stress and apoptosis initiation. On the other hand, ORF7a utilizes the ubiquitin system to impede and escape host elimination, providing a promising potential target for developing strategies for minimizing the COVID-19 pandemic. IMPORTANCE Viruses struggle to reproduce after infecting cells, and the host eliminates infected cells through apoptosis to prevent virus spread. Cells adopt a special ubiquitination code to protect against viral infection, while ORF7a manipulates and exploits the ubiquitin system to eliminate host cells' effect on apoptosis and redirect cellular pathways in favor of virus survival. Our results revealed that SARS-CoV-2-encoded accessory protein ORF7a recruits prosurvival factor BclXL to the ER and activates the cellular ER stress response resulting in the initiation of programmed death to remove virus-infected cells. Ubiquitination of ORF7a blocked the recruitment of BclXL and suppressed the ER stress response, which helps to counteract cell apoptosis and rescue cell fate. These findings help us understand the mechanism of SARS-CoV-2 invasion and contribute to a theoretical foundation for the clinical prevention of COVID-19.

Oxidative Stress Markers and Sperm DNA Fragmentation in Men Recovered from COVID-19

SARS-CoV-2 negatively affects semen characteristics, impairs various biochemical processes in seminal fluid and within spermatogenic cells ultimately leading to male fertility decline. However, the distinct mechanisms, in particular, the role of oxidative stress on the consequences of coronavirus infection, have not been well investigated, which is the purpose of the present study. The standard semen parameters, its pro- and antioxidant system state, as well as the level of sperm DNA fragmentation, were assessed in 17 semen samples of men five months after the coronavirus infection and in 22 age-matched control patients. We determined that the DNA fragmentation rate negatively correlated with the period after coronavirus recovery, as well as seminal fluid superoxide dismutase activity and uric acid level. It was demonstrated that COVID-19 is not always associated with increased DNA fragmentation, allowing them to be considered as two independent factors. Thus, the most significant changes were noted in the samples of men after COVID-19 and abnormal TUNEL results: increased round cell number, decreased seminal fluid's nitrotyrosine level, and total antioxidant capacity and Zn, as well as an increased 8-hydroxy-2'-deoxyguanosine level within spermatozoa. The data obtained indicate that increased DNA fragmentation and diminished semen quality in men can be the result of an imbalance in semen pro- and antioxidant components after COVID-19.

Molecular Mechanisms Related to Responses to Oxidative Stress and Antioxidative Therapies in COVID-19: A Systematic Review

The coronavirus disease (COVID-19) pandemic is a leading global health and economic challenge. What defines the disease’s progression is not entirely understood, but there are strong indications that oxidative stress and the defense against reactive oxygen species are crucial players. A big influx of immune cells to the site of infection is marked by the increase in reactive oxygen and nitrogen species. Our article aims to highlight the critical role of oxidative stress in the emergence and severity of COVID-19 and, more importantly, to shed light on the underlying molecular and genetic mechanisms. We have reviewed the available literature and clinical trials to extract the relevant genetic variants within the oxidative stress pathway associated with COVID-19 and the anti-oxidative therapies currently evaluated in the clinical trials for COVID-19 treatment, in particular clinical trials on glutathione and N-acetylcysteine.

Programmed cell death lives

Research on cell death mechanisms gets a lot of attention. This is understandable as it underlies biology in general, as well as the insight in pathological conditions and the development of opportunities for therapeutic intervention. Over the last years a steady rise in the number of scientific reports and in the impact of this literature on the different mechanisms of programmed cell death can be observed. A number of new concepts are highlighted.

SARS-CoV-2, COVID-19, and Reproduction: Effects on Fertility, Pregnancy, and Neonatal Life

Since its discovery in Wuhan, China, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread over the world, having a huge impact on people’s lives and health. The respiratory system is often targeted in people with the coronavirus disease 2019 (COVID-19). The virus can also infect many organs and tissues in the body, including the reproductive system. The consequences of the SARS-CoV-2 infection on fertility and pregnancy in hosts are poorly documented. Available data on other coronaviruses, such as severe acute respiratory syndrome (SARS-CoV) and Middle Eastern Respiratory Syndrome (MERS-CoV) coronaviruses, identified pregnant women as a vulnerable group with increased pregnancy-related complications. COVID-19 was also shown to impact pregnancy, which can be seen in either the mother or the fetus. Pregnant women more likely require COVID-19 intensive care treatment than non-pregnant women, and they are susceptible to giving birth prematurely and having their newborns admitted to the neonatal intensive care unit. Angiotensin converting enzyme 2 (ACE2), a key player of the ubiquitous renin-angiotensin system (RAS), is the principal host cellular receptor for SARS-CoV-2 spike protein. ACE2 is involved in the regulation of both male and female reproductive systems, suggesting that SARS-CoV-2 infection and associated RAS dysfunction could affect reproduction. Herein, we review the current knowledge about COVID-19 consequences on male and female fertility, pregnant women, and their fetuses. Furthermore, we describe the effects of COVID-19 vaccination on reproduction.

Metabolic, Oxidative and Psychological Stress as Mediators of the Effect of COVID-19 on Male Infertility: A Literature Review

Over 300 million patients with coronavirus disease 2019 (COVID-19) have been reported worldwide since the outbreak of the pandemic in Wuhan, Hubei Province, China. COVID-19 is induced by the acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The effect of SARS-CoV-2 infection on the male reproductive system is unclear. The aim of this review is to assess the effect of SARS-CoV-2 infection on male fertility and the impact of possible mediators, such as metabolic, oxidative and psychological stress. SARS-CoV-2 infection aggravates metabolic stress and directly or indirectly affects male fertility by reducing seminal health. In addition, SARS-CoV-2 infection leads to excessive production of reactive oxygen species (ROS) and increased psychological distress. These data suggest that SARS-CoV-2 infection reduces male fertility, possibly by means of metabolic, oxidative and psychological stress. Therefore, among other consequences, the possibility of COVID-19-induced male infertility should not be neglected.

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

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

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

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

COVID-19, Oxidative Stress, and Male Reproductive Dysfunctions: Is Vitamin C a Potential Remedy?

Few peculiarities have been observed in the etiology of coronavirus disease 2019 (COVID-19), one such being its greater prevalence in men than women partly due to the higher expressions of angiotensin-converting enzyme-2 (ACE2) in the male reproductive tissues. Recent scientific reports are in line with some of the evidence-based hypotheses in the initial phase of the COVID-19 pandemic, regarding the involvement of oxidative stress (OS) and oxidant-sensitive pathways in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection-mediated male reproductive disruptions. The seminal dissemination of SARS-CoV-2 or its components, testicular disruptions due to viral infection and oxidative damage in the testis have all been evidenced recently. High-dose of antioxidants, such as vitamin C, have been shown to be a useful treatment for COVID-19 patients, to alleviate systemic inflammation and OS. In addition, vitamin C is a major testicular antioxidant that neutralizes excess reactive oxygen species (ROS), prevents sperm agglutination, prevents lipid peroxidation, recycles vitamin E, and protects against DNA damage. Thus, the present review aims to discuss the mechanism of COVID-19-mediated male reproductive dysfunctions, based on the evidence available so far, and explore the possibility of using vitamin C in alleviating testicular OS and associated damage caused by COVID-19.

COVID-19, Oxidative Stress and Male Reproduction: Possible Role of Antioxidants

Coronavirus disease 2019 (COVID-19) involves a complex pathogenesis and with the evolving novel variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the long-term impacts of the unceasing COVID-19 pandemic are mostly uncertain. Evidence indicates deleterious impact of this disease upon male reproductive health. It is concerning that COVID-19 may contribute to the already global declining trend of male fertility. The adverse impacts of COVID-19 on male reproduction may primarily be attributed to the induction of systemic inflammatory responses and oxidative stress (OS), which operate as a vicious loop. Bringing the systemic inflammation to a halt is critical for ‘putting out’ the ‘cytokine storm’ induced by excessive reactive oxygen species (ROS) generation. The possibility of OS playing a prime role in COVID-19-mediated male reproductive dysfunctions has led to the advocacy of antioxidant therapy. An array of antioxidant defense medications has shown to be effective in experimental and clinical studies of COVID-19. The present review thus discusses the possibilities as to whether antioxidant drugs would contribute to combating the SARS-CoV-2 infection-induced male reproductive disruptions, thereby aiming at kindling research ideas that are needed for identification and treatment of COVID-19-mediated male reproductive impairments.

COVID-19 Vaccination Does Not Affect Reproductive Health Parameters in Men

With the implementation of COVID-19 vaccine up-take, doubts regarding the impact of immunization on future fertility have begun to emerge. We have examined vaccine safety on male reproductive health. We set up a multicentre (three infertility centers), retrospective study in order to assess semen parameters and fertilization rate of one hundred-six men in a pairwise comparison between the first and second assisted reproduction technology (ART) attempt, performed respectively before and after COVID-19 vaccination. Median time (range) between the first vaccine dose and the second ART cycle was 75 days (39-112). Semen parameters did not change before and after the exposure. Fertilization rate was also similar before and after vaccination. Twenty-five patients (24%) were oligozoospermic before the vaccination while 26 (25%) after the exposure (P = 0.87). Severe asthenozoospermia were present in 11 patients before as well as after the exposure. No difference was observed even after considering different types of vaccines (mRNA or viral vector). COVID-19 vaccination did not affect sperm quality and fertilization capacity of men undergoing ART treatments and should be considered safe for men's reproductive health.

Viral Infections and Male Infertility: A Comprehensive Review of the Role of Oxidative Stress

Viral infections have been a part of human existence to date, though viruses have posed a huge threat with various outbreaks lately. These threats are associated with reproductive health challenges, especially male infertility. The prime focus of this review is to highlight the mechanisms associated with viral infection-induced male infertility/subfertility and identify new treatment strategies with the aim to preserve male fertility. The reviewed data showed that viral infections stimulate inflammatory responses, resulting in the release of proinflammatory cytokines, which induces oxidative stress. This oxido-inflammatory cycle could continue in a vicious cycle and threaten male fertility. Existing data from human and experimental studies show that viral infection-induced oxido-inflammatory response results in testicular damage, atrophy of the seminiferous tubules and Sertoli cells, and reduced Leydig cell mass. This is accompanied by reduced circulatory testosterone, impaired spermatogenesis, reduced sperm motility, lipid peroxidation, DNA fragmentation and apoptosis of the sperm cells. Based on the available pieces of evidence, antioxidant therapy, in vivo and in vitro, may be beneficial and protects against the potential risk of male infertility from viral infection. It is, however recommended that more clinical studies be conducted to demonstrate the possible protective roles of antioxidants used as adjuvant therapy in viral infections, and in the in vitro treatment of semen samples for those utilizing semen washing and artificial reproductive techniques.

Impact of COVID-19 on male fertility

COVID-19, the clinical condition caused by the SARS-CoV-2 virus, has been associated with massive cytokine storm and damage to multiple organ systems. Although evidence for the detection of SARS-CoV-2 virus in the testis remains scarce, testicular damage and dysregulation of gonadotropins associated with inflammation has been reported. Additionally, as a result of the rapidly evolving pandemic, frequently updated medical interventions and public policies leading to delays of care can play a role in fertility. This narrative review aims to summarize the current literature on how COVID-19 may influence male fertility.

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.

Coronavirus disease and male fertility: a systematic review

BACKGROUND

Based on the information from other SARS-CoV infections in the patients recovered from COVID-19, particularly cases in the reproductive age, gonadal function evaluation and andrological consultation comprising semen analysis are recommended.

MAIN BODY

Based on the COVID-19 infected patients' seminal fluid analyses, SARS-CoV-2 may employ the male reproductive system as a transmission pathway. It has been also demonstrated that angiotensin-converting enzyme 2 (ACE2) can be strongly expressed at the protein levels in the testicular cells. The high expression of ACE2 in testes suggests that testes in the COVID-19 infected males can have an important role in the viral persistence and this subject needs further investigations. Several researchers have examined males recovered from COVID-19, but still, large-scale experiments are needed to determine the effects of SARS-CoV-2 on the male reproductive system as well as viral transmission risk.

CONCLUSION

Comprehensive researches are required to figure out the presence of the SARS-CoV-2 virus in seminal fluid as well as its sexual transmissibility and impact on sperm characteristics.

Roles of PRR-Mediated Signaling Pathways in the Regulation of Oxidative Stress and Inflammatory Diseases

Oxidative stress is a major contributor to the pathogenesis of various inflammatory diseases. Accumulating evidence has shown that oxidative stress is characterized by the overproduction of reactive oxygen species (ROS). Previous reviews have highlighted inflammatory signaling pathways, biomarkers, molecular targets, and pathogenetic functions mediated by oxidative stress in various diseases. The inflammatory signaling cascades are initiated through the recognition of host cell-derived damage associated molecular patterns (DAMPs) and microorganism-derived pathogen associated molecular patterns (PAMPs) by pattern recognition receptors (PRRs). In this review, the effects of PRRs from the Toll-like (TLRs), the retinoic acid-induced gene I (RIG-I)-like receptors (RLRs) and the NOD-like (NLRs) families, and the activation of these signaling pathways in regulating the production of ROS and/or oxidative stress are summarized. Furthermore, important directions for future studies, especially for pathogen-induced signaling pathways through oxidative stress are also reviewed. The present review will highlight potential therapeutic strategies relevant to inflammatory diseases based on the correlations between ROS regulation and PRRs-mediated signaling pathways.