COVID-19 causes neuronal degeneration and reduces neurogenesis in human hippocampus.

Recent investigations of COVID-19 have largely focused on the effects of this novel virus on the vital organs in order to efficiently assist individuals who have recovered from the disease. In the present study we used hippocampal tissue samples extracted from people who died after COVID-19. Utilizing histological techniques to analyze glial and neuronal cells we illuminated a massive degeneration of neuronal cells and changes in glial cells morphology in hippocampal samples. The results showed that in hippocampus of the studied brains there were morphological changes in pyramidal cells, an increase in apoptosis, a drop in neurogenesis, and change in spatial distribution of neurons in the pyramidal and granular layer. It was also demonstrated that COVID-19 alter the morphological characteristics and distribution of astrocyte and microglia cells. While the exact mechanism(s) by which the virus causes neuronal loss and morphology in the central nervous system (CNS) remains to be determined, it is necessary to monitor the effect of SARS-CoV-2 infection on CNS compartments like the hippocampus in future investigations. As a result of what happened in the hippocampus secondary to COVID-19, memory impairment may be a long-term neurological complication which can be a predisposing factor for neurodegenerative disorders through neuroinflammation and oxidative stress mechanisms.

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.

COVID-19 disrupts the blood-testis barrier through the induction of inflammatory cytokines and disruption of junctional proteins.

OBJECTIVE: Junctional proteins are the most important component of the blood-testis barrier and maintaining the integrity of this barrier is essential for spermatogenesis and male fertility. The present study elucidated the effect of SARS-CoV-2 infection on the blood-testis barrier (BTB) in patients who died from severe acute respiratory syndrome coronavirus 2 (COVID-19) complications. METHODS: In this study, lung and testis tissue was collected from autopsies of COVID-19 positive (n = 10) and negative men (n = 10) and was taken for stereology, immunocytochemistry, and RNA extraction. RESULTS: Evaluation of the lung tissue showed that the SARS-CoV-2 infection caused extensive damage to the lung tissue and also increases inflammation in testicular tissue and destruction of the testicular blood barrier. Autopsied testicular specimens of COVID-19 showed that COVID-19 infection significantly changes the spatial arrangement of testicular cells and notably decreased the number of Sertoli cells. Moreover, the immunohistochemistry results showed a significant reduction in the protein expression of occluding, claudin-11, and connexin-43 in the COVID-19 group. In addition, we also observed a remarkable enhancement in protein expression of CD68 in the testes of the COVID-19 group in comparison with the control group. Furthermore, the result showed that the expression of TNF-α, IL1ß, and IL6 was significantly increased in COVID-19 cases as well as the expression of occludin, claudin-11, and connexin-43 was decreased in COVID-19 cases. CONCLUSIONS: Overall, the present study demonstrated that SARS-CoV-2 could induce the up-regulation of the pro-inflammatory cytokine and down-regulation of junctional proteins of the BTB, which can disrupt BTB and ultimately impair spermatogenesis.

Inflammatory Response Leads to Neuronal Death in Human Post-Mortem Cerebral Cortex in Patients with COVID-19.

The recent coronavirus disease of 2019 (COVID-19) pandemic has adversely affected people worldwide. A growing body of literature suggests the neurological complications and manifestations in response to COVID-19 infection. Herein, we explored the inflammatory and immune responses in the post-mortem cerebral cortex of patients with severe COVID-19. The participants comprised three patients diagnosed with severe COVID-19 from March 26, 2020, to April 17, 2020, and three control patients. Our findings demonstrated a surge in the number of reactive astrocytes and activated microglia, as well as low levels of glutathione along with the upregulation of inflammation- and immune-related genes IL1B, IL6, IFITM, MX1, and OAS2 in the COVID-19 group. Overall, the data imply that oxidative stress may invoke a glial-mediated neuroinflammation, which ultimately leads to neuronal cell death in the cerebral cortex of COVID-19 patients.

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

To evaluate the incidence of apoptosis within the testes of patients who died from severe acute respiratory syndrome coronavirus 2 (COVID-19) complications, testis tissue was collected from autopsies of COVID-19 positive (n = 6) and negative men (n = 6). They were then taken for histopathological experiments, and RNA extraction, to examine the expression of angiotensin-converting enzyme 2 (ACE2), transmembrane protease, serine 2 (TMPRSS2), BAX, BCL2 and Caspase3 genes. Reactive oxygen species (ROS) production and glutathione disulfide (GSH) activity were also thoroughly examined. Autopsied testicular specimens of COVID-19 showed that COVID-19 infection significantly decreased the seminiferous tubule length, interstitial tissue and seminiferous tubule volume, as well as the number of testicular cells. An analysis of the results showed that the Johnsen expressed a reduction in the COVID-19 group when compared to the control group. Our data showed that the expression of ACE2, BAX and Caspase3 were remarkably increased as well as a decrease in the expression of BCL2 in COVID-19 cases. Although, no significant difference was found for TMPRSS2. Furthermore, the results signified an increase in the formation of ROS and suppression of the GSH activity as oxidative stress biomarkers. The results of immunohistochemistry and TUNEL assay showed that the expression of ACE2 and the number of apoptotic cells significantly increased in the COVID-19 group. Overall, this study suggests that COVID-19 infection causes spermatogenesis disruption, probably through the oxidative stress pathway and subsequently induces apoptosis.

Proinflammatory Cytokines in the Olfactory Mucosa Result in COVID-19 Induced Anosmia.

Studies have found increased rates of dysosmia in patients with Novel Coronavirus disease 2019 (COVID-19). However, the mechanism that causes olfactory loss is unknown. The primary objective of this study was to explore local proinflammatory cytokine levels in the olfactory epithelium in patients with COVID-19. Biopsies of the olfactory epithelium were taken from patients with confirmed COVID-19 as well as uninfected controls. Levels of tumor necrosis factor α (TNF-α) and interleukin-1-beta (IL-1ß) were assessed using ELISA and compared between groups. Average TNF-α levels were significantly increased in the olfactory epithelium of the COVID-19 group compared to the control group (P < 0.05). However, no differences in IL-1ß were seen between groups. Elevated levels of the proinflammatory cytokine TNF-α were seen in the olfactory epithelium in patients with COVID-19. This suggests that direct inflammation of the olfactory epithelium could play a role in the acute olfactory loss described in many patients with COVID-19.