Periodontitis promotes the expression of gingival transmembrane serine protease 2 (TMPRSS2), a priming protease for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

OBJECTIVES

The oral cavity is one of the main entry sites for SARS-CoV-2. Gingival keratinocytes express transmembrane serine protease 2 (TMPRSS2), responsible for priming the SARS-CoV-2 spike protein. We investigated whether periodontitis increased the expression of TMPRSS2.

METHODS

To investigate gene expression in periodontitis, we analyzed the expression of specific genes from (1) the Gene Expression Omnibus (GEO) dataset of 247 human gingival tissues and (2) an experimentally-induced periodontitis mouse model. Human gingival tissues with or without periodontitis were immunohistochemically stained using an anti-TMPRSS2 antibody. Analysis of the TMPRSS2 promoter was performed using a ChIP-Atlas dataset. TMPRSS2 expression was detected in cultured human keratinocytes using quantitative reverse transcription (qRT)-PCR and Western blot analysis.

RESULTS

GEO dataset analysis and an experimentally-induced periodontitis model revealed increased expression of TMPRSS2 in periodontitis gingiva. The keratinocyte cell membrane in periodontitis gingiva was strongly immunohistochemically stained for TMPRSS2. Using ChIP-Atlas and GEO datasets, we screened for transcription factors that bind to the TMPRSS2 promoter region. We found one candidate, estrogen receptor 1 (ESR1), highly expressed in periodontitis gingiva. Analysis of the GEO dataset revealed a correlation between ESR1 and TMPRSS2 expression in gingival tissues. An ESR1 ligand induced TMPRSS2 expression in cultured keratinocytes.

CONCLUSIONS

Periodontitis increases TMPRSS2 expression in the cell membrane of gingival keratinocytes.