Phenotype and Functional Features of Human Telomerase Reverse Transcriptase Immortalized Human Airway Smooth Muscle Cells from Asthmatic and Non-Asthmatic Donors

J K Burgess,A Ketheson,A J Halayko,J P T Ward,K A Limbert Rempel,B G Oliver,A Faiz

doi:10.1038/s41598-017-18429-0

Abstract

Asthma is an obstructive respiratory disease characterised by chronic inflammation with airway hyperresponsiveness. In asthmatic airways, there is an increase in airway smooth muscle (ASM) cell bulk, which differs from non-asthmatic ASM in characteristics. This study aimed to assess the usefulness of hTERT immortalisation of human ASM cells as a research tool. Specifically we compared proliferative capacity, inflammatory mediator release and extracellular matrix (ECM) production in hTERT immortalised and parent primary ASM cells from asthmatic and non-asthmatic donors. Our studies revealed no significant differences in proliferation, IL-6 and eotaxin-1 production, or CTGF synthesis between donor-matched parent and hTERT immortalised ASM cell lines. However, deposition of ECM proteins fibronectin and fibulin-1 was significantly lower in immortalised ASM cells compared to corresponding primary cells. Notably, previously reported differences in proliferation and inflammatory mediator release between asthmatic and non-asthmatic ASM cells were retained, but excessive ECM protein deposition in asthmatic ASM cells was lost in hTERT ASM cells. This study shows that hTERT immortalised ASM cells mirror primary ASM cells in proliferation and inflammatory profile characteristics. Moreover, we demonstrate both strengths and weaknesses of this immortalised cell model as a representation of primary ASM cells for future asthma pathophysiological research.

Highlights

A network of extracellular matrix (ECM) proteins
This study shows for the first time that human telomerase reverse transcriptase (hTERT) immortalised airway smooth muscle (ASM) cells provide a useful tool for characterising mechanisms relating to differences in tissue inflammatory responses in asthma, as they mirror unique hyper-secretory characteristics of primary ASM cells from asthmatic donors[13,14,15,16,17]
Using donor-matched parent and immortalised cell lines, we reveal that hTERT immortalised ASM cell cultures retain a similar proliferative response, inflammatory profile and growth factor production as parent primary ASM cell cultures

Summary

Introduction

A network of extracellular matrix (ECM) proteins. Typically, these proteins act as support structures for the cells, they are biologically active and can influence aspects of the ASM’s cellular functions[8,9,10,11,12,13]. The same study reported that TGF-β stimulated asthmatic ASM cells deposited increased amounts of fibulin-1 in the matrix than non-asthmatic cells. These changes in fundamental functional properties of ASM from asthmatics support an important role in disease pathophysiology. Primary cells are isolated from ASM bundles – dissected from human lung tissue obtained by lung resection, transplant or biopsy - and expanded in culture[28] They provide a model for studying in vivo cellular responses[29], major limitations in routinely using primary ASM cell cultures include obtaining primary tissue, from asthmatics, and the limited number of cell doublings that ASM cells can undergo before they lose fundamental phenotypic features of ASM, change morphology or undergo senescence.

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