Constitutive TRIM22 expression within the respiratory tract identifies tissue-specific and cell-type dependent intrinsic immune barriers to influenza A virus infection

Charman, M. et al. (2019) Constitutive TRIM22 expression within the respiratory tract identifies tissue-specific and cell-type dependent intrinsic immune barriers to influenza A virus infection. bioRxiv, (doi:10.1101/679159) (Early Online Publication)

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We hypothesized that increased expression of antiviral host factors at portals of viral entry may protect exposed tissues from the constant threat of invading pathogens. Comparative transcriptomic analysis identified the broad-acting restriction factor TRIM22 (TRIpartite Motif 22) to be among the most abundantly expressed antiviral host factors in the lung, a major portal of entry for many respiratory pathogens. This was surprising, as TRIM22 is currently considered to be an interferon stimulated gene (ISG) product that confers protection following the activation of pathogen-induced cytokine-mediated innate immune defences. Using human respiratory cell lines and the airways of rhesus macaques, we experimentally confirmed high levels of constitutive TRIM22 expression in the lung. In contrast, TRIM22 expression in many widely used transformed cell lines could only be observed following immune stimulation. Endogenous levels of TRIM22 in non-transformed cells were sufficient to restrict human and avian influenza A virus (IAV) infection by inhibiting the onset of viral transcription independently of cytokine-mediated innate immune defences. Thus, TRIM22 confers a pre-existing (intrinsic) tissue-specific immune barrier to IAV infection in the respiratory tract. We investigated whether the constitutive expression of TRIM22 was a characteristic shared by other ISGs in human lung tissue. Transcriptomic analysis identified a large group of ISGs and IAV immuno-regulatory host factors that were similarly enriched in the lung relative to other mucosal tissues, but whose expression was downregulated in transformed cell-lines. We identify common networks of immune gene downregulation which correlated with enhanced permissivity of transformed cells to initiate IAV replication. Our data highlight the importance of tissue-specific and cell-type dependent patterns of pre-existing immune gene expression in the intrinsic intracellular restriction of IAV; findings highly relevant to the immune regulation of many clinically important respiratory pathogens.

Item Type:Articles
Status:Early Online Publication
Glasgow Author(s) Enlighten ID:Digard, Professor Paul and Boutell, Dr Chris and Wojtus, Joanna and Sloan, Dr Elizabeth and Hutchinson, Dr Edward and McFarlane, Mr Steven and Charman, Mr Matthew
Authors: Charman, M., McFarlane, S., Wojtus, J. K., Sloan, E., Dewar, R., Leeming, G., Al-Saadi, M., Hunter, L., Carroll, M., Stewart, J. P., Digard, P., Hutchinson, E., and Boutell, C.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:bioRxiv
Publisher:Cold Spring Harbor Laboratory
Copyright Holders:Copyright © 2019 The Authors
Publisher Policy:Reproduced under a Creative Commons License
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