SARS-CoV-2 Enters Human Leydig Cells and Affects Testosterone Production In Vitro.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a SARS-like coronavirus, continues to produce mounting infections and fatalities all over the world. Recent data point to SARS-CoV-2 viral infections in the human testis. As low testosterone levels are associated with SARS-CoV-2 viral infections in males and human Leydig cells are the main source of testosterone, we hypothesized that SARS-CoV-2 could infect human Leydig cells and impair their function. We successfully detected SARS-CoV-2 nucleocapsid in testicular Leydig cells of SARS-CoV-2-infected hamsters, providing evidence that Leydig cells can be infected with SARS-CoV-2. We then employed human Leydig-like cells (hLLCs) to show that the SARS-CoV-2 receptor angiotensin-converting enzyme 2 is highly expressed in hLLCs. Using a cell binding assay and a SARS-CoV-2 spike-pseudotyped viral vector (SARS-CoV-2 spike pseudovector), we showed that SARS-CoV-2 could enter hLLCs and increase testosterone production by hLLCs. We further combined the SARS-CoV-2 spike pseudovector system with pseudovector-based inhibition assays to show that SARS-CoV-2 enters hLLCs through pathways distinct from those of monkey kidney Vero E6 cells, a typical model used to study SARS-CoV-2 entry mechanisms. We finally revealed that neuropilin-1 and cathepsin B/L are expressed in hLLCs and human testes, raising the possibility that SARS-CoV-2 may enter hLLCs through these receptors or proteases. In conclusion, our study shows that SARS-CoV-2 can enter hLLCs through a distinct pathway and alter testosterone production.

Could Lower Testosterone in Older Men Explain Higher COVID-19 Morbidity and Mortalities?

The health scourge imposed on humanity by the COVID-19 pandemic seems not to recede. This fact warrants refined and novel ideas analyzing different aspects of the illness. One such aspect is related to the observation that most COVID-19 casualties were older males, a tendency also noticed in the epidemics of SARS-CoV in 2003 and the Middle East respiratory syndrome in 2012. This gender-related difference in the COVID-19 death toll might be directly involved with testosterone (TEST) and its plasmatic concentration in men. TEST has been demonstrated to provide men with anti-inflammatory and immunological advantages. As the plasmatic concentration of this androgen decreases with age, the health benefit it confers also diminishes. Low plasmatic levels of TEST can be determinant in the infection's outcome and might be related to a dysfunctional cell Ca2+ homeostasis. Not only does TEST modulate the activity of diverse proteins that regulate cellular calcium concentrations, but these proteins have also been proven to be necessary for the replication of many viruses. Therefore, we discuss herein how TEST regulates different Ca2+-handling proteins in healthy tissues and propose how low TEST concentrations might facilitate the replication of the SARS-CoV-2 virus through the lack of modulation of the mechanisms that regulate intracellular Ca2+ concentrations.

Immune system and COVID-19 by sex differences and age.

In COVID-19 disease, are reported gender differences in relation to severity and death. The aim of this review is to highlight gender differences in the immune response to COVID-19. The included studies were identified using PubMed, until 30 October 2020. The search included the following keywords: SARS-CoV-2, COVID-19, gender, age, sex, and immune system. Literature described that females compared to males have greater inflammatory, antiviral, and humoral immune responses. In female, estrogen is a potential ally to alleviate SARS-COV-2 disease. In male, testosterone reduces vaccination response and depresses the cytokine response. In the older patients, and in particular, in female older patients, it has been reported a progressive functional decline in the immune systems. Differences by gender were reported in infection diseases, including SARS-CoV-2. These data should be confirmed by the other epidemiological studies.

Increased COVID-19 infections in women with polycystic ovary syndrome: a population-based study.

OBJECTIVE: Several recent observational studies have linked metabolic comorbidities to an increased risk from COVID-19. Here we investigated whether women with PCOS are at an increased risk of COVID-19 infection. DESIGN: Population-based closed cohort study between 31 January 2020 and 22 July 2020 in the setting of a UK primary care database (The Health Improvement Network, THIN). METHODS: The main outcome was the incidence of COVID-19 coded as suspected or confirmed by the primary care provider. We used Cox proportional hazards regression model with stepwise inclusion of explanatory variables (age, BMI, impaired glucose regulation, androgen excess, anovulation, vitamin D deficiency, hypertension, and cardiovascular disease) to provide unadjusted and adjusted hazard risks (HR) of COVID-19 infection among women with PCOS compared to women without PCOS. RESULTS: We identified 21 292 women with a coded diagnosis of PCO/PCOS and randomly selected 78 310 aged and general practice matched control women. The crude COVID-19 incidence was 18.1 and 11.9 per 1000 person-years among women with and without PCOS, respectively. Age-adjusted Cox regression analysis suggested a 51% higher risk of COVID-19 among women with PCOS compared to women without PCOS (HR: 1.51 (95% CI: 1.27-1.80), P < 0.001). After adjusting for age and BMI, HR reduced to 1.36 (1.14-1.63)], P = 0.001. In the fully adjusted model, women with PCOS had a 28% increased risk of COVID-19 (aHR: 1.28 (1.05-1.56), P = 0.015). CONCLUSION: Women with PCOS are at an increased risk of COVID-19 infection and should be specifically encouraged to adhere to infection control measures during the COVID-19 pandemic. SIGNIFICANCE STATEMENT: Women with polycystic ovary syndrome (PCOS) have an increased risk of cardio-metabolic disease, which have been identified as a risk factor for COVID-19. To investigate whether the increased metabolic risk in PCOS translates into an increased risk of COVID-19 infection, we carried out a population-based closed cohort study in the UK during its first wave of the SARS-CoV-2 pandemic (January to July 2020), including 21 292 women with PCOS and 78 310 controls matched for sex, age and general practice location. Results revealed a 52% increased risk of COVID-19 infection in women with PCOS, which remained increased at 28% above controls after adjustment for age, BMI, impaired glucose regulation and other explanatory variables.

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.

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.

Gender Disaggregation in COVID-19 and Increased Male Susceptibility.

Novel coronavirus disease 2019 (COVID-19) is a growing public health crisis. Despite initial focus on the elderly population with comorbidities, it seems that large studies from the worst affected countries follow a sex-disaggregation pattern. Analysis of available data showed marked variations in reported cases between males and females among different countries with higher mortality in males.  At this early stage of the pandemic, medical datasets at the individual level are not available; therefore, it is challenging to conclude how different factors have impacted COVID-19 susceptibility. Thus, in the absence of patients' level data, we attempted to provide a theoretical description of how other determinants have affected COVID-19 susceptibility in males compared to females.  In this article, we have identified and discussed possible biological and behavioral factors that could be responsible for the increased male susceptibility. Biological factors include - an absence of X-chromosomes (a powerhouse for immune-related genes), a high level of testosterone that inhibits antibody production, and the presence of Angiotensin-converting enzyme 2 (ACE2) receptors that facilitate viral replication. Similarly, behavioral factors constitute - higher smoking and alcohol consumptions, low level of handwashing practices, and high-risk behavior like non-adherence to health services and reluctance to follow public health measures in males. Keywords: COVID-19; gender; males; sex disaggregation; susceptibility.

Sex steroids skew ACE2 expression in human airway: a contributing factor to sex differences in COVID-19?

The incidence, severity, and mortality of ongoing coronavirus infectious disease 19 (COVID-19) is greater in men compared with women, but the underlying factors contributing to this sex difference are still being explored. In the current study, using primary isolated human airway smooth muscle (ASM) cells from normal males versus females as a model, we explored the effect of estrogen versus testosterone in modulating the expression of angiotensin converting enzyme 2 (ACE2), a cell entry point for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Using confocal imaging, we found that ACE2 is expressed in human ASM. Furthermore, Western analysis of ASM cell lysates showed significantly lower ACE2 expression in females compared with males at baseline. In addition, ASM cells exposed to estrogen and testosterone for 24 h showed that testosterone significantly upregulates ACE2 expression in both males and females, whereas estrogen downregulates ACE2, albeit not significant compared with vehicle. These intrinsic and sex steroids induced differences may help explain sex differences in COVID-19.

Why does COVID-19 kill more elderly men than women? Is there a role for testosterone?

BACKGROUND: Recent epidemiological data indicate that there may be a gender predisposition to COVID-19, with men predisposed to being most severely affected, and older men accounting for most deaths. OBJECTIVES: Provide a review of the research literature, propose hypotheses, and therapies based on the potential link between testosterone (T) and COVID-19 induced mortality in elderly men. MATERIALS AND METHODS: A search of publications in academic electronic databases, and government and public health organization web sites on T, aging, inflammation, severe acute respiratory syndrome (SARS) due to coronavirus (CoV) 2 (SARS-CoV-2) infection, and COVID-19 disease state and outcomes was performed. RESULTS: The link between T, the immune system, and male aging is well-established, as is the progressive decline in T levels with aging. In women, T levels drop before menopause and variably increase with advanced age. Elevated IL-6 is a characteristic biomarker of patients infected with COVID-19 and has been linked to the development of the acute respiratory distress syndrome (ARDS). Thus far, half of the admitted COVID-19 patients developed ARDS, half of these patients died, and elderly male patients have been more likely to develop ARDS and die. Low T is associated with ARDS. These data suggest that low T levels may exacerbate the severity of COVID-19 infection in elderly men. It may also stand to reason that normal T levels may offer some protection against COVID-19. SARS-CoV-2 binds to the angiotensin-converting enzyme 2, present in high levels in the testis. CONCLUSION: At present, it is not known whether low T levels in aging hypogonadal males create a permissive environment for severe responses to COVID-19 infection or if the virus inhibits androgen formation. Given the preponderance of COVID-19 related mortality in elderly males, additional testing for gonadal function and treatment with T may be merited.

SARS-CoV-2, testosterone and frailty in males (PROTEGGIMI): A multidimensional research project.

Preliminary published data depict a much greater prevalence of males with laboratory-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) referred for intensive care unit admission and severe sequelae in several countries. In this context, males seem to not only be more susceptible to the infection compared to female subjects, at least in Western countries, but their case fatality rate attributable to SARS-CoV-2 infection is also highest. Therefore, we may speculate that the different hormonal milieu could have a more profound pathophysiological role in association with SARS-CoV-2, with endogenous testosterone leaving men more prone to develop more serious complications related to the SARS-CoV-2 infection. Another option is that SARS-CoV-2 infection per se causes an acute stage of male hypogonadism, the depletion of androgenic action triggering serious or an even fatal course of the disease. Therefore, we strongly advocate the development of a prospective multidimensional andrological translational research project in men, which we called the PROTEGGIMI study. In this Opinion Article, we will not only highlight novel research activity in this area but also invite other researchers and learned scientific societies to join us in our efforts to understand an important and very newly discovered gap in knowledge, which may have serious implications for the lives of millions of men.