SARS-CoV-2 Suppresses Human Beta-Defensin-1 (hBD-1) and Ionocyte Proteins that Control Ion Homeostasis and Innate Immunity in the Oral Mucosa

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Presentation Time: 03:15 PM - 04:30 PM
Poster Board Number: B228
Abstract ID: 5330

Presenting Author:
Lisa K Ryan , Associate Professor at Univ. of Louisville, Univ. of Florida Col. of Med.

Abstract:

COVID-19 has affected innate immune responses in the respiratory tract, but its effect on the oral cavity has only recently been described. In addition to the lung and nasal cavity, the minor and major salivary gland ducts and acini are infected by SARS-CoV-2, the virus responsible for this disease. The ducts contain ionocyte cells that are thought to control pH and ion homeostasis. Ionocytes are marked by FoxI1, a transcription factor that controls their development. In addition, hBD-1, which is involved in anti-viral innate immunity, is highly expressed in oral, nasal and lung ionocytes. Buccal scrapings from 72 patients with and without omicron COVID-19 (recovered and non-COVID-19) were analyzed for gene expression via quantitative RT-PCR of hBD-1 and FoxI1, and of proteins controlling ion influx - CFTR, ASCL3 and NKCC1. Except for CFTR, all mRNA levels (relative to beta-actin) were significantly decreased in COVID-19 patients, and only NKCC1 remained depressed in recovered COVID-19 patients. CFTR mRNA remained unchanged compared with the non-Covid19 and recovered patients. Immunohistochemistry on normal minor salivary gland sections revealed that FoxI1, CFTR, ASCL3 and hBD-1 are associated in proximity in the duct. NKCC1 was in these ducts but was also found in other locations. In conclusion, SARS-CoV-2 may modulate innate immunity in the oral cavity, as indicated by the decrease in hBD-1 and key ionocyte proteins, possibly changing pH and osmolality in salivary glands.