Role of microRNAs and effects of substrate, age and stretch in experimental models for IPF.

Scotto di Mase, Michele (2020) Role of microRNAs and effects of substrate, age and stretch in experimental models for IPF. PhD thesis, University of Liverpool.

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Abstract

Pulmonary fibrosis (IPF) is a debilitating progressive disease mostly affecting the elderly, and due to dysregulated wound healing repair. It is characterised by increased matrix production and altered ECM composition, leading to increased tissue rigidity, and eventually, death. In mammalian lungs, mechanical stretch is generated by the diaphragm and chest muscles and transferred first to lung septa and then at cellular level. In lung fibrosis the increase in ECM causes mechanical stretch impairment due to the increase in tissue stiffness, which is thought to be mostly dependant on increased fibrillar collagen. Using an ad hoc in vitro system, the effects of collagen as culture substrate, age and mechanical stretch on several ECM genes were investigated in both primary and immortalised lung cells. My results indicated profibrotic roles for collagen as a substrate and age, while mechanical stretch appeared to have a protective role against fibrosis. Pharmacological use of microRNAs to fine tune mRNA expression is a novel field of research. MicroRNA based therapies either aim to increase expression of a microRNA to repress a target mRNA (mirmimics), or decrease microRNA expression to upregulate a target mRNA (antagomir). Analysis of microRNA expression in the Bleomycin mouse model of lung fibrosis identified more than 20 microRNAs that were significantly modified in their expression during fibrosis induction and progression. Using the Bleomycin model, I identified 4 microRNAs (miR-21a-5p, miR-34a- 5p, miR- 29a-3p and miR-378-5p) as potential pro-fibrotic microRNAs due to progressively increased expression correlated with progression of fibrotic features. Results from primary mouse fibroblast cultures showed that overexpression of miR-29a- 3p results in a reduction of Col1a1 expression, suggesting an antifibrotic role for this microRNA. miR-21a-5p expression decreased Smad7 expression in both primary mouse lung fibroblasts and in the Bleomycin model of lung fibrosis. Treatment with a miR-21a mirmimic resulted in increased lung fibrosis in the Bleomycin mouse model, while treatment with a miR- 21a antagomir resulted in reduced lung fibrosis. My results identify miR-21a repression as a potential novel strategy to treat IPF.

Item Type:	Thesis (PhD)
Divisions:	Faculty of Health and Life Sciences > Institute of Life Courses and Medical Sciences
Depositing User:	Symplectic Admin
Date Deposited:	09 Sep 2021 14:55
Last Modified:	18 Jan 2023 21:35
DOI:	10.17638/03131368
Supervisors:	Van 'T Hof, Rob
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3131368