RESUMEN
Lethal COVID-19 is associated with respiratory failure that is thought to be caused by acute respiratory distress syndrome (ARDS) secondary to pulmonary infection. To date, the cellular pathogenesis has been inferred from studies describing the expression of ACE2, a transmembrane protein required for SARS-CoV-2 infection, and detection of viral RNA or protein in infected humans, model animals, and cultured cells. To functionally test the cellular mechanisms of COVID-19, we generated hACE2 fl animals in which human ACE2 (hACE2) is expressed from the mouse Ace2 locus in a manner that permits cell-specific, Cre-mediated loss of function. hACE2 fl animals developed lethal weight loss and hypoxemia within 7 days of exposure to SARS-CoV-2 that was associated with pulmonary infiltrates, intravascular thrombosis and patchy viral infection of lung epithelial cells. Deletion of hACE2 in lung epithelial cells prevented viral infection of the lung, but not weight loss, hypoxemia or death. Inhalation of SARS-CoV-2 by hACE2 fl animals resulted in early infection of sustentacular cells with subsequent infection of neurons in the neighboring olfactory bulb and cerebral cortexâ" events that did not require lung epithelial cell infection. Pharmacologic ablation of the olfactory epithelium or Foxg1 Cre mediated deletion of hACE2 in olfactory epithelial cells and neurons prevented lethality and neuronal infection following SARS-CoV-2 infection. Conversely, transgenic expression of hACE2 specifically in olfactory epithelial cells and neurons in Foxg1 Cre ; LSL- hACE2 mice was sufficient to confer neuronal infection associated with respiratory failure and death. These studies establish mouse loss and gain of function genetic models with which to genetically dissect viral-host interactions and demonstrate that lethal disease due to respiratory failure may arise from extrapulmonary infection of the olfactory epithelium and brain. Future therapeutic efforts focused on preventing olfactory epithelial infection may be an effective means of protecting against severe COVID-19.
RESUMEN
Extracellular vesicles (EVs) are a unique mode of intercellular communication capable of incredible specificity in transmitting signals involved in cellular function, including germ cell maturation. Spermatogenesis occurs in the testes, behind a protective barrier to ensure safeguarding of germline DNA from environmental insults. Following DNA compaction, further sperm maturation occurs in the epididymis. Here, we report reproductive tract EVs transmit information regarding stress in the paternal environment to sperm, potentially altering fetal development. Using intracytoplasmic sperm injection, we found that sperm incubated with EVs collected from stress-treated epididymal epithelial cells produced offspring with altered neurodevelopment and adult stress reactivity. Proteomic and transcriptomic assessment of these EVs showed dramatic changes in protein and miRNA content long after stress treatment had ended, supporting a lasting programmatic change in response to chronic stress. Thus, EVs as a normal process in sperm maturation, can also perform roles in intergenerational transmission of paternal environmental experience.
