COVID-19-associated changes in nasal mucosa: Insights from inflammatory and epithelial cell profiling

Coronavirus disease of 2019 (COVID-19), caused by Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), primarily affects nasal cavities by binding its spike proteins to angiotensin-converting enzyme 2 (ACE2) receptors. This study aimed to assess inflammatory and epithelial cell counts and determine their ratios in exfoliated nasal mucosal cells of COVID-19 suspected patients.

This cross-sectional study was conducted at All India Institute of Medical Sciences (AIIMS), Mangalagiri, from August to October 2022, involving 75 COVID-19 suspected patients. Nasal smears were collected, stained with Papanicolaou test (PAP), and analyzed for inflammatory and epithelial cell counts. Participants were grouped as COVID-19 positive and negative based on Real Time Polymerase Chain Reaction (RT-PCR) results. Genotoxicity factors were evaluated using mean and standard deviation values.

In COVID-19 positive individuals, mean cell counts for neutrophils, eosinophils, lymphocytes, mast cells, macrophages, and epithelial cells were 42.08, 6.68, 4.48, 0.84, 0.12, and 45.80, respectively. In COVID-19 negative patients, the corresponding values were 38.08, 13.76, 11.12, 2.66, 0.22, and 34.16. The inflammatory ratios for neutrophils to eosinophils and neutrophils to lymphocytes in COVID-19 positive individuals were 7.30 and 14.06, respectively. SARS-CoV-2 infection resulted in elevated neutrophil and epithelial cell counts and decreased eosinophil, lymphocyte, mast cell, and macrophage count.

SARS-CoV-2 exhibits unique immunological alterations in nasal mucosa. The inflammatory ratios of neutrophils-to-eosinophils and neutrophils-to-lymphocytes may serve as reliable diagnostic markers for COVID-19.