Autopsy Study of Testicles in COVID-19: Upregulation of Immune-Related Genes and Downregulation of Testis-Specific Genes

Abstract

Context Infection by SARS-CoV-2 may be associated with testicular dysfunction that could affect male fertility. Objective Testicles of fatal COVID-19 cases were investigated to detect virus in tissue and to evaluate histopathological and transcriptomic changes. Methods Three groups were compared: a. uninfected controls (subjects dying of trauma or sudden cardiac death; n = 10); b. subjects dying of COVID-19 (virus-negative in testes; n = 15); c. subjects dying of COVID-19 (virus-positive in testes; n = 9). SARS-CoV-2 genome and nucleocapsid antigen were probed using RT-PCR, in situ hybridization, immunohistochemistry (IHC). Infiltrating leukocytes were typed by IHC. mRNA transcripts of immune-related and testis-specific genes were quantified using the nCounter method. Results SARS-CoV-2 was detected in testis tissue of 9/24 (37%) COVID-19 cases accompanied by scattered T-cell and macrophage infiltrates. Size of testicles and counts of spermatogenic cells were not significantly different among groups. Analysis of mRNA transcripts showed that in virus-positive testes immune processes were activated (interferon-alpha and -gamma pathways). By contrast, transcription of 12 testis-specific genes was downregulated, independently of virus positivity in tissue. By IHC, expression of the luteinizing hormone/choriogonadotropin receptor was enhanced in virus-positive compared to virus-negative testicles, while expression of receptors for androgens and the follicle-stimulating hormone were not significantly different among groups. Conclusion In lethal COVID-19 cases, infection of testicular cells is not uncommon. Viral infection associates with activation of interferon pathways and downregulation of testis-specific genes involved in spermatogenesis. Due to the exceedingly high numbers of infected people in the pandemic, the impact of virus on fertility should be further investigated.

Testis-Specific Genes Deregulation in the Testis of COVID-19 Patients: A Potential Driver of Spermatogenesis Disruption?

“…Furthermore, a position statement of the Italian Society of Andrology and Sexual Medicine (SIAMS) did not support SARS-CoV-2 presence in semen and risk of sexual transmission by speculating that semen viral clearance might overlap with clinical recovery or that perhaps the virus does not reach semen ( 2 ). In line with these data, in the study by Basolo and coworkers, mean time from initial symptoms to death was significantly shorter in cases with SARS-CoV-2–positive testes ( 4 ). Although SARS-CoV-2 was rarely detected in semen, few studies highlighted a significant impairment of semen quality in Covid-19 patients.…”

“…These results, in line with a previous autopsy study on a few testis samples ( 6 ), testify that SARS-CoV-2 infection triggers cellular and humoral immune changes at an early stage, potentially causing orchitis and consequent testicular damage ( 3 ). A third finding of the study ( 4 ) highlighted that testis-specific genes were downregulated in the testes of Covid-19 cases, independently of SARS-CoV-2 presence, compared with controls ( 4 ). These results, in line with a previous autopsy study on a few testis samples ( 6 ), demonstrated for the first time that expression of selected testis-specific genes enriched in spermatids was reduced independently of infiltrating immune cell counts ( 4 ).…”

“…Hypothesized mechanisms included Leydig and Sertoli cells disruption, local inflammatory response eliciting orchitis and ensuing increased oxidative stress and spermatozoa DNA damage, as well as adverse effects of therapies, which therefore shed doubts on direct SARS-CoV-2 contribution to semen quality impairment ( 3 ). A second finding of the study ( 4 ) highlighted that inflammatory cell infiltrates were more abundant and immune-related genes upregulated in the testes of Covid-19 cases, independently of SARS-CoV-2 presence, compared with controls. These results, in line with a previous autopsy study on a few testis samples ( 6 ), testify that SARS-CoV-2 infection triggers cellular and humoral immune changes at an early stage, potentially causing orchitis and consequent testicular damage ( 3 ).…”

“…The study reports a new mechanistic hypothesis of testis and spermatogenesis disruption induced by SARS-CoV-2. A first finding of the study by Basolo and coworkers ( 4 ) highlighted that one-third of Covid-19 cases displayed SARS-CoV-2–positive testes, with predominant interstitial localization, and testis size, histopathological characteristics, and spermatogenic cells counts similar to controls. These results are partially in line with a previous autopsy study ( 5 ) consistently reporting no spermatogenic damage but failing to detect testicular SARS-CoV-2 positivity, probably because of more prolonged admission to death timing, encompassing viral clearance.…”

“…The greater male susceptibility to Covid-19 sequelae and the strong male genital tract expression of angiotensin-converting enzyme 2 and transmembrane protease serine 2, essential components of SARS-CoV-2 cell entry machinery ( 1-3 ), suggested investigation of Covid-19–mediated testicular dysfunction, potentially including infertility. In the Journal of Clinical Endocrinology & Metabolism , Basolo and coworkers ( 4 ) reported the innovative results of an autopsy-based observational study investigating testicular expression of immune-related and testis-specific genes in the largest series of fatal Covid-19 cases, including both SARS-CoV-2–negative and SARS-CoV-2–positive testes, compared with control cases of abrupt death from noninfectious causes. The study reports a new mechanistic hypothesis of testis and spermatogenesis disruption induced by SARS-CoV-2.…”