THE ROLE OF MIR-149-5P IN REGULATING INFLAMMATORY RESPONSES AND INJURY OF AIRWAY EPITHELIAL CELLS IN MODELS OF RESPIRATORY VIRAL INFECTIONS

  • Nafeesa Shahdab

Student thesis: Doctoral Thesis

Abstract

Respiratory viruses disrupt normal homeostasis of airway epithelial cells and induce
inflammation, injury, and repair processes. MicroRNAs (miRNAs) are crucial regulators of
various physiological and pathological conditions. Particularly miR-149-5p is predicted to
target inflammatory (e.g interleukin-6 (IL-6)) and wound repair markers (e.g tumour protein
63 (p63)). However, the role of miR-149-5p in airway epithelium remains unclear. This
study examined the effect of viral pathogen-associated molecular patterns (PAMPs),
polyinosinic:polycytidylic acid (poly (I:C)), on cell viability and IL-6 release from bronchial
(BEAS-2B) and alveolar (A549) epithelial cells in different culture conditions. This study
also explored the role of miR-149-5p in modulating IL-6 and p63 expression in airway
epithelial cells in response to poly (I:C) or severe acute respiratory syndrome coronavirus 2
(SARS-CoV-2) spike protein 1 or 2 (S1 or S2) subunits. The outcomes indicated that BEAS-
2B cells incubated with poly (I:C) exhibited reduced cell viability and increased IL-6 release
in serum-free conditions compared to complete media, with no significant effects observed
in A549 cells. Further, poly (I:C) suppressed miR-149-5p levels, which correlated with the
increased release of IL-6 and expression of p63 and toll-like receptor (TLR)-3, a poly (I:C)
receptor, in BEAS-2B cells. Poly (I:C) also downregulated miR-149-5p and upregulated IL-
6 expression in A549 cells; however, p63 and TLR3 were undetectable. In addition, ectopic
overexpression of miR-149-5p in BEAS-2B cells inhibited IL-6 and p63 mRNA expression
and suppressed poly (I:C)-mediated IL-6 and p63 expression. Moreover, miR-149-5p
directly targeted the IL-6 mRNA in BEAS-2B cells. The S1 or S2 subunit did not affect miR-
149-5p expression in either cell type; however, the S1 subunit induced IL-6 release in BEAS-
2B cells uniquely expressing the S1 subunit receptor, TLR2. These findings suggested that
different culture conditions affected cell viability and IL-6 release from BEAS-2B cells in
response to poly (I:C). This study highlighted that TLR3 and TLR2 expression differences
at baseline may contribute to the distinct responses of BEAS-2B cells to poly (I:C) and S1
subunit compared with A549 cells. These findings also indicated that TLR3-mediated miR-
149-5p dysregulation significantly increased IL-6 and p63 expression in BEAS-2B cells.
These outcomes elucidated the specific regulatory mechanisms of miR-149-5p in airway
epithelial cells, highlighting its potential as a therapeutic target for managing viral-induced
airway inflammation and injury.
Date of Award11 Dec 2024
Original languageEnglish
Awarding Institution
  • Teesside University
SupervisorFatemeh Moheimani (Supervisor)

Cite this

'