Severe acute respiratory syndrome coronavirus 2 may exploit human transcription factors involved in retinoic acid and interferon-mediated response: a hypothesis supported by an in silico analysis.

The pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19), resulting in acute respiratory disease, is a worldwide emergency. Because recently it has been found that SARS-CoV is dependent on host transcription factors (TF) to express the viral genes, efforts are required to understand the molecular interplay between virus and host response. By bioinformatic analysis, we investigated human TF that can bind the SARS-CoV-2 sequence and can be involved in viral transcription. In particular, we analysed the key role of TF involved in interferon (IFN) response. We found that several TF could be induced by the IFN antiviral response, specifically some induced by IFN-stimulated gene factor 3 (ISGF3) and by unphosphorylated ISGF3, which were found to promote the transcription of several viral open reading frame. Moreover, we found 22 TF binding sites present only in the sequence of virus infecting humans but not bat coronavirus RaTG13. The 22 TF are involved in IFN, retinoic acid signalling and regulation of transcription by RNA polymerase II, thus facilitating its own replication cycle. This mechanism, by competition, may steal the human TF involved in these processes, explaining SARS-CoV-2's disruption of IFN-I signalling in host cells and the mechanism of the SARS retinoic acid depletion syndrome leading to the cytokine storm. We identified three TF binding sites present exclusively in the Brazilian SARS-CoV-2 P.1 variant that may explain the higher severity of the respiratory syndrome. These data shed light on SARS-CoV-2 dependence from the host transcription machinery associated with IFN response and strengthen our knowledge of the virus's transcription and replicative activity, thus paving the way for new targets for drug design and therapeutic approaches.

Craniofacial cephalometric evaluation in habitual snorers with and without obstructive sleep apnea.

Cephalometry has been used to evaluate soft tissue and craniofacial dimensions in moderate-to-severe obstructive sleep apnea syndrome (OSA), but rarely in habitual snoring, the preclinical stage of OSA. This study deals with craniofacial bone measurements in a sample of 28 male habitual snorers with and without OSA, and 10 healthy non-snorers. Habitual snorers showed a significant decrease in sagittal dimensions of the cranial base and mandibular bone; there was also a shorter maxilla in group B (apnea plus hypopnea index more than 10) with respect to group A (apnea plus hypopnea index less or equal to 10). Facial height and angle dimensions were not different between snorers and non-snorers. These findings indicate that some habitual snorers may have some anatomic disposition to upper airway obstruction during sleep.