DNA methylation and gene expression pattern of ACE2 and TMPRSS2 genes in saliva samples of patients with SARS-CoV-2 infection

COVID-19 caused by SARS-CoV-2 became a pandemic affecting the health and economy of the world. Although it was known that this virus uses ACE2 protein along with TMPRSS2 to enter the host cell, the methylation pattern and gene expression of ACE2 and TMPRSS2 genes are not explored in saliva samples of patients infected with COVID-19. The study aimed to quantify promoter methylation of ACE2 and TMPRSS2 along with its mRNA expression in saliva samples of COVID-19 patients in order to understand the regulatory mechanism of these genes in SARS-CoV-2 infection. Saliva samples were collected from thirty male patients with SARS-CoV-2 infection and thirty age-matched healthy control male subjects. Q MS PCR and qRT PCR was performed to quantify the promoter DNA methylation and mRNA expression of ACE2 and TMPRSS2 respectively. Our study didnt find any significant difference between methylation and expression of these two genes in cases compared to control subjects. However there was significant positive correlation between DNA methylation of ACE2 and its gene expression. Among cases, the sample collected [≥]7 days after appearance of symptoms showed higher amount of methylation in both ACE2 and TMPRSS2 genes when compared to sample collected before 7 days. In conclusion, we found that ACE2 and TMPRSS2 methylation plays a role in COVID-19.