SARS-CoV-2 ORF3a expression in brain disrupts the autophagy-lysosomal pathway, impairs sphingolipid homeostasis, and drives neuropathogenesis.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causes injury to multiple organ systems, including the brain. SARS-CoV-2's neuropathological mechanisms may include systemic inflammation and hypoxia, as well as direct cell damage resulting from viral infections of neurons and glia. How the virus directly causes injury to brain cells, acutely and over the long term, is not well understood. In order to gain insight into this process, we studied the neuropathological effects of open reading frame 3a (ORF3a), a SARS-CoV-2 accessory protein that is a key pathological factor of the virus. Forced ORF3a brain expression in mice caused the rapid onset of neurological impairment, neurodegeneration, and neuroinflammation-key neuropathological features found in coronavirus disease (COVID-19, which is caused by SARS-CoV-2 infection). Furthermore, ORF3a expression blocked autophagy progression in the brain and caused the neuronal accumulation of α-synuclein and glycosphingolipids, all of which are linked to neurodegenerative disease. Studies with ORF3-expressing HeLa cells confirmed that ORF3a disrupted the autophagy-lysosomal pathway and blocked glycosphingolipid degradation, resulting in their accumulation. These findings indicate that, in the event of neuroinvasion by SARS-CoV-2, ORF3a expression in brain cells may drive neuropathogenesis and be an important mediator of both short- and long-term neurological manifestations of COVID-19.

Increases in Bdnf DNA Methylation in the Prefrontal Cortex Following Aversive Caregiving Are Reflected in Blood Tissue.

Child maltreatment not only leads to epigenetic changes, but also increases the risk of related behavioral deficits and mental disorders. These issues presumably are most closely associated with epigenetic changes in the brain, but epigenetic changes in peripheral tissues like blood are often examined instead, due to their accessibility. As such, the reliability of using the peripheral epigenome as a proxy for that of the brain is imperative. Previously, our lab has found aberrant methylation at the Brain-derived neurotrophic factor (Bdnf) gene in the prefrontal cortex of rats following aversive caregiving. The current study examined whether aversive caregiving alters Bdnf DNA methylation in the blood compared to the prefrontal cortex. It was revealed that DNA methylation associated with adversity increased in both tissues, but this methylation was not correlated between tissues. These findings indicate that group trends in Bdnf methylation between blood and the brain are comparable, but variation exists among individual subjects.

Preventing epigenetic traces of caregiver maltreatment: A role for HDAC inhibition.

Reorganization of the brain's epigenetic landscape occurs alongside early adversity in both human and non-human animals. Whether this reorganization is simply incidental to or is a causal mechanism of the behavioral abnormalities that result from early adversity is important to understand. Using the scarcity-adversity model of low nesting resources in Long Evans rats, our lab has previously reported specific epigenetic and behavioral trajectories occurring in response to early disruption of the caregiving environment. To further probe that relationship, the current work investigates the ability of the epigenome-modifying drug sodium butyrate to prevent maltreatment-induced methylation changes when administered alongside maltreatment. Following exposure to the scarcity-adversity model, during which drug was administered prior to each caregiving session, methylation of Brain-derived Neurotrophic Factor (Bdnf) IX DNA was examined in the Prefrontal Cortex (PFC) of male and female pups at postnatal day (PN) 8. As our previous work reports, increased methylation at this exon of Bdnf in the PFC is a stable epigenetic change across the lifespan that occurs in response to early maltreatment, thus giving us a suitable starting point to investigate pharmacological prevention of maltreatment-induced epigenetic marks. Here we also examined off-target effects of sodium butyrate by assessing methylation in another region of Bdnf (exon IV) not affected in the infant brain as well as global levels of methylation in the brain region of interest. Results indicate that a 400 mg/kg (but not 300 mg/kg) dose of sodium butyrate is effective in preventing the maltreatment-induced rise in methylation at Bdnf exon IX in the PFC of male (but not female) infant pups. Administration of sodium butyrate did not affect the methylation status of Bdnf IV or overall levels of global methylation in the PFC, suggesting potential specificity of this drug. These data provide us an avenue forward for investigating whether the relationship between adversity-induced epigenetic outcomes in our model can be manipulated to improve behavioral outcomes.