ACE2 and TMPRSS2 are expressed on the human ocular surface, suggesting susceptibility to SARS-CoV-2 infection

  1. Lingli Zhou
  2. Zhenhua Xu
  3. Gianni M. Castiglione
  4. Uri S. Soiberman
  5. Charles G. Eberhart
  6. Elia J. Duh

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Abstract

Purpose

Conjunctival signs and symptoms are observed in a subset of patients with COVID-19, and SARS-CoV-2 has been detected in tears, raising concerns regarding the eye both as a portal of entry and carrier of the virus. The purpose of this study was to determine whether ocular surface cells possess the key factors required for cellular susceptibility to SARS-CoV-2 entry/infection.

Methods

We analyzed human post-mortem eyes as well as surgical specimens for the expression of ACE2 (the receptor for SARS-CoV-2) and TMPRSS2, a cell surface-associated protease that facilitates viral entry following binding of the viral spike protein to ACE2.

Results

Across all eye specimens, immunohistochemical analysis revealed expression of ACE2 in the conjunctiva, limbus, and cornea, with especially prominent staining in the superficial conjunctival and corneal epithelial surface. Surgical conjunctival specimens also showed expression of ACE2 in the conjunctival epithelium, especially prominent in the superficial epithelium, as well as the substantia propria. All eye and conjunctival specimens also expressed TMPRSS2. Finally, western blot analysis of protein lysates from human corneal epithelium obtained during refractive surgery confirmed expression of ACE2 and TMPRSS2.

Conclusions

Together, these results indicate that ocular surface cells including conjunctiva are susceptible to infection by SARS-CoV-2, and could therefore serve as a portal of entry as well as a reservoir for person-to-person transmission of this virus. This highlights the importance of safety practices including face masks and ocular contact precautions in preventing the spread of COVID-19 disease.

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  1. ScreenIT

    SciScore for 10.1101/2020.05.09.086165: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementIRB: Study protocols were approved by the Institutional Review Board at the Johns Hopkins School of Medicine, and study participants underwent informed consent by the treating surgeon. 2.2.
    Consent: Study protocols were approved by the Institutional Review Board at the Johns Hopkins School of Medicine, and study participants underwent informed consent by the treating surgeon. 2.2.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Anti-ACE2 (ab108252, 1:1000) and anti-TMPRSS2 (ab92323, 1:1000) antibodies were purchased from Abcam.
    Anti-ACE2
    suggested: (Abcam Cat# ab108252, RRID:AB_10864415)
    ab108252
    suggested: (Abcam Cat# ab108252, RRID:AB_10864415)
    anti-TMPRSS2
    suggested: (Abcam Cat# ab92323, RRID:AB_10585592)
    ab92323
    suggested: (Abcam Cat# ab92323, RRID:AB_10585592)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  2. ScreenIT

    SciScore for 10.1101/2020.05.09.086165: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementStudy protocols were approved by the Institutional Review Board at the Johns Hopkins School of Medicine , and study participants underwen informed consent by the treating surgeon . 2.2 .Randomizationnot detected.Blindingnot detected.Power Analysisnot detected.Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Total After blocking in 5 % normal goat serum diluted in PBS , the sections were incubated with anti-ACE2 antibody ( ab108252 , 1: 100 , Abcam , Cambridge , MA) , anti-TMPRSS2 antibody ( ab92323 , 1: 1000 , Abcam ) and the isotype- and concentration-matched normal IgG control ( ab172730 , Abcam ) overnigh o at 4 C .
    anti-ACE2
    suggested: (Abcam Cat# ab108252, AB_10864415)
    For both corneal and lung sections , immunohistochemical staining with isotype IgG isotype antibody staining was performed , as negative controls ( Fig . 5D , G and J) . 3.6 . Grading of ACE2 and TMPRSS2 expression in epithelium on the ocular surface As an additional analysis , we graded the staining intensities of ACE2 and TMPRSS2 on the ocular surfa from 10 post-mortem eye specimens with particular attention to their expression in epithelium .
    isotype IgG
    suggested: None
    Paraffin- embedded human eye sections were processed for immunohistochemistry with rabbit anti-TMPRSS2 antibody.
    anti-TMPRSS2
    suggested: None
    Paraffin-embedde human surgical conjunctival sections were analyzed by immunohistochemistry with rabbit anti-TMPRS antibody.
    anti-TMPRS
    suggested: None
    Software and Algorithms
    SentencesResources
    The susceptibility of the conjunctival to infection with SARS-CoV-2 provides further context for publish clinical studies .
    SARS-CoV-2
    suggested: (Sino Biological Cat# 40143-R019, AB_2827973)

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore is not a substitute for expert review. SciScore checks for the presence and correctness of RRIDs (research resource identifiers) in the manuscript, and detects sentences that appear to be missing RRIDs. SciScore also checks to make sure that rigor criteria are addressed by authors. It does this by detecting sentences that discuss criteria such as blinding or power analysis. SciScore does not guarantee that the rigor criteria that it detects are appropriate for the particular study. Instead it assists authors, editors, and reviewers by drawing attention to sections of the manuscript that contain or should contain various rigor criteria and key resources. For details on the results shown here, including references cited, please follow this link.

  3. Version published to 10.1101/2020.05.09.086165 on bioRxiv