Physiological implications of COVID-19 in reproduction: angiotensin-converting enzyme 2 a key player.

The COVID-19 outbreak, caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), was first identified in China, and it has quickly become a global threat to public health due to its rapid rate of transmission and fatalities. Angiotensin-converting enzyme 2 (ACE2) has been identified as a receptor that mediates the entry of SARS-CoV-2 into human cells, as in the case of severe acute respiratory syndrome coronavirus (SARS-CoV). Several studies have reported that ACE2 expression is higher in Leydig, Sertoli and seminiferous ductal cells of males, as well as in ovarian follicle cells of females, suggesting possible potential pathogenicity of the coronavirus in the reproductive system. Higher ACE2 expression in the human placenta and reports of vertical transmission of SARS-CoV-2 among clinical cases have increased the relevance of further studies in this area. This review focuses on the interaction between SARS-CoV-2 and the ACE2 receptor and speculates on the mechanistic interplay in association with male and female reproductive physiology. In addition, based on the available literature, we discuss the alleged sex differences in terms of the infectivity of SARS-CoV-2, which is claimed greater among males, and further explore the physiological role of ACE2 and 17ß-oestradiol for the same.

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

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

SARS-CoV-2 infection and impact on female genital tract: An untested hypothesis.

COVID pandemic consists one of the most challenging medical realities. Apart from affecting respiratory system, current evidence has demonstrated multiorgan manifestations that SARS-Cov-2 infection may actually have. However, one of the medical hypotheses not yet thoroughly tested is the impact on female reproductive system and more specifically cervix. No large observational studies have been performed to test presence of SARS-Cov-2 in cervical samples, while potential correlation and impact on HPV infection has not yet been examined. In this context, our research team has already planned to begin a prospective observational study regarding detection rates of SARS-CoV-2 genetic material in cervical cytology. The collected specimen will be analyzed for the presence of COVID-19 genetic material and in case of positive results, HPV typing will be performed as well in order to detect potential correlations between SARS-CoV-2 infection and HPV-infection. We would therefore like to launch our idea to control for SARS-CoV-2 infection in cervical specimen as well as examine potential correlation with HPV infection. Potential scientific proof of such hypothesis would change much regarding follow-up of HPV-positive patients while also triggering further research regarding aitiopathogenetic pathways of COVID. Communication of such a medical hypothesis could potentially motivate colleagues worldwide to expand their interest also on the research of SARS-CoV-2 cervical infection, in an effort to optimize our level of knowledge towards this new threatening and unknown reality of SARS-CoV-2.

Potential influence of COVID-19/ACE2 on the female reproductive system.

The 2019 novel coronavirus (2019-nCoV) appeared in December 2019 and then spread throughout the world rapidly. The virus invades the target cell by binding to angiotensin-converting enzyme (ACE) 2 and modulates the expression of ACE2 in host cells. ACE2, a pivotal component of the renin-angiotensin system, exerts its physiological functions by modulating the levels of angiotensin II (Ang II) and Ang-(1-7). We reviewed the literature that reported the distribution and function of ACE2 in the female reproductive system, hoping to clarify the potential harm of 2019-nCoV to female fertility. The available evidence suggests that ACE2 is widely expressed in the ovary, uterus, vagina and placenta. Therefore, we believe that apart from droplets and contact transmission, the possibility of mother-to-child and sexual transmission also exists. Ang II, ACE2 and Ang-(1-7) regulate follicle development and ovulation, modulate luteal angiogenesis and degeneration, and also influence the regular changes in endometrial tissue and embryo development. Taking these functions into account, 2019-nCoV may disturb the female reproductive functions through regulating ACE2.