Background: The mechanism underlying non-severe and severe
asthma remains unclear although it is commonly associated with increased
airway smooth muscle (ASM) mass. Long non-coding RNAs (lncRNAs) are known
to be important in regulating healthy primary ASM cells whilst changed
expression has been observed in CD8 T-cells from patients with severe
asthma.
Methods: Primary ASM cells were isolated from healthy individuals (n=9),
patients classified as having non-severe asthma (n=9) or severe asthma
(n=9). ASM cells were exposed to dexamethasone and fetal calf serum
(FCS). mRNA and lncRNA expression was measured by microarray and
quantitative real-time PCR. Bioinformatic analysis was used to examine
for relevant biological pathways. Finally, the lncRNA; Plasmacytoma
Variant Translocation (PVT1) was inhibited by transfection of primary ASM
cells with siRNAs, and the effect upon ASM cell phenotype was examined.
Results: The mRNA expression profile was significantly different between
patient groups following exposure to dexamethasone and FCS and these were
associated with biological pathways that may be relevant to the
pathogenesis of asthma including cellular proliferation and pathways
associated with glucocorticoid activity. We also observed a significant
change in the expression of lncRNAs, yet only one (PVT1) is decreased in
expression in the corticosteroid sensitive non-severe asthmatics, and
increased in expression in the corticosteroid-insensitive severe
asthmatics. Subsequent targeting studies demonstrated the importance of
this lncRNA in controlling both proliferation and IL-6 release in ASM
cells from patients with severe asthma.
Conclusions: lncRNAs are associated with the aberrant phenotype observed
in ASM cells from patients with asthma. Targeting of PVT1 may be
effective in reducing airway remodelling in asthma.