High expression of SARS-CoV2 viral entry-related proteins in human limbal stem cells

Abstract

Purpose:

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV2). While the ocular surface is considered one of the major SARS-CoV2 transmission routes, the specific cellular tropism of SARS-CoV2 is not fully understood. In the current study, we evaluated the expression and regulation of two SARS-CoV2 viral entry proteins, TMPRSS2 and ACE2, in human ocular epithelial cells and stem cells.

Methods:

TMPRSS2 and ACE2 expression in ABCB5-positive limbal stem cells (LSCs) were assessed by RNAseq, flow cytometry and immunohistochemistry. PAX6, TMPRSS2, and ACE2 mRNA expression values were obtained from the GSE135455 and DRA002960 RNA-seq datasets. siRNA-mediated PAX6 knockdown (KD) was performed in limbal and conjunctival epithelial cells. TMPRSS2 and ACE2 expression in the PAX6 KD cells was analyzed by qRT-PCR and Western blot.

Results:

We found that ABCB5-positive LSCs express high levels of TMPRSS2 and ACE2 compared to ABCB5-negative limbal epithelial cells. Mechanistically, gene knockout and overexpression models revealed that the eye transcription factor PAX6 negatively regulates TMPRSS2 expression. Therefore, low levels of PAX6 in ABCB5-positive LSCs promote TMPRSS2 expression, and high levels of TMPRSS2 and ACE2 expression by LSCs indicate enhanced susceptibility to SARS-CoV2 infection in this stem cell population.

Conclusions:

Our study points to a need for COVID-19 testing of LSCs derived from donor corneas before transplantation to patients with limbal stem cell deficiency. Furthermore, our findings suggest that expandable human ABCB5+ LSC cultures might represent a relevant novel model system for studying cellular SARS-CoV2 viral entry mechanisms and evaluating related targeting strategies.

RAS ID

42680

Document Type

Journal Article

Date of Publication

1-1-2022

Volume

23

Funding Information

National Institutes of Health grants 1K99EY031741, 1R01EY025794, R24EY028767 , Schepens Core grant P30EY003790, grant 2T32EB016652-06

PubMed ID

34653711

School

School of Medical and Health Sciences

Copyright

free_to_read

Publisher

Elsevier

Comments

Sasamoto, Y., Lee, C. A., Yoshihara, M., Martin, G., Ksander, B. R., Frank, M. H., & Frank, N. Y. (2022). High expression of SARS-CoV2 viral entry-related proteins in human limbal stem cells. The ocular surface, 23, 197-200.

https://doi.org/10.1016/j.jtos.2021.10.002

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Link to publisher version (DOI)

10.1016/j.jtos.2021.10.002