The role of ace2 receptor and its age related immunity in covid-19

ABSTRACT

World is facing the Coronavirus pandemic, which is resulting in large number of deaths and economic burden to the society. SARS-CoV-2 is the causative agent for COVID-19 infection. SARS-CoV-2 is a single stranded RNA molecule which enters the human through ACE2 receptor. ACE2 is widely expressed in the human tissues, primarily in the heart, kidney and testis and secondarily in the lungs, blood vessels and colon. Therefore, SARS-CoV-2 can infect the lungs and other organs as well leading to multiple organ damage. ACE2 receptor regulates the Renin Angiotensin System (RAS). Therefore, increasing SARS-CoV-2 infection decreases ACE2 receptor and results in dysfunction of RAS, imbalance of blood pressure and inflammation of airways. This provide direct link between the ACE2 receptor and COVID-19 infection. ACE2 expression and immune response may fluctuate throughout the life of human which accounts for variation of disease severity. ACE2 level decreases with age i.e. children have higher expression of ACE2 as compared to the older people and children also possess strong innate immunity leading to early control of the infection comparing to older people. Hence, children are found to be less susceptible to COVID19 infection then the older ones. The difference in ACE2 expression and host immune response to SARS-CoV-2 infection can explain the severity of disease progression in different age, gender and race.