Comparative immunohistochemical evaluation of variable expression of ACE2 and TMPRSS2 in different age groups

Abstract

Background and objectives: COVID-19 pandemic declared by World Health Organisation has drastically upsurged the death rate in the past three years. The specific host cell receptors for viral spike protein have been identified as Angiotensin Converting Enzyme 2 (ACE2) and Transmembrane Serine Protease 2 (TMPRSS2). The study aimed to evaluate the variation in the pattern of expression of ACE2 and TMPRSS2 by immunohistochemistry in the oral and nasopharyngeal mucosa of different age groups. Methods: Total of 40 patients were recruited for the study and segregated to four groups. Oral tissue samples from patients of age 18-40 years and 41-70 years were grouped as group I, group II respectively. Nasal tissue from 18-40 years was grouped as III and 41-70 years old as group IV. Immunohistochemical expression of ACE and TMPRSS2 were studied in the tissue samples. Scoring was done based on the intensity and percentage of staining and quantitative image analysis using Fiji image analysis software. Independent sample t‐test was done to compare the mean difference in pattern of expression among the age groups studied. Pearson correlation coefficient was done to correlate the expression with age. Statistical significance was set at value less than 0.05. Results: The mean difference in expression was significant for ACE2 (p=0.01) & TMPRSS2 (p=0.02) expression in oral tissue. Both ACE2 and TMPRSS2 expression showed positive correlation between the groups. Conclusion: Age-specific variation might provide deeper understanding of clinical severity and elaborate the validation of therapeutic targets.