AGER expression and alternative splicing in bronchial biopsies of smokers and never smokers

Abstract

Cigarette smoking is one of the major risk factors for the development of chronic obstructive pulmonary disease (COPD). Evidence is accumulating that Receptor for Advanced Glycation-End products (RAGE)-signaling is a key pathway in the pathophysiology of COPD. To date, it is unknown how smoking affects RAGE expression. In the current study, we investigated the effect of smoking on AGER , the gene encoding RAGE, expression and on alternative splicing of AGER . To this end, we conducted RNA-Seq on bronchial biopsies for asymptomatic smokers ( n = 36) and never smokers ( n = 40). Total AGER gene expression was accessed using DESeq2, while alternative splicing was investigated by measuring the number of specific split reads spanning exon-exon junctions and the total split reads. One of the major isoforms of RAGE is endogenous soluble (es) RAGE, an anti-inflammatory decoy receptor, making up for approximately 10% of the total amount of soluble (s)RAGE. We found that smokers show decreased total gene expression of AGER in bronchial biopsies, while the relative abundance of the esRAGE isoform is increased. Furthermore, no difference in the serum levels of total sRAGE were observed between smokers and non-smokers. Our data indicates that smoking initiates a protective anti-inflammatory mechanism with decreased expression of the pro-inflammatory gene AGER and increased relative abundance of the anti-inflammatory isoform esRAGE.

RAGE and TLR4 differentially regulate airway hyperresponsiveness: Implications for COPD

“…We have previously shown that current smoking is associated with significantly lower levels of AGER bronchial gene expression in healthy subjects 34 (Figure 6A; Table 1). Thus, we extended these studies to determine whether smoking impacts TLR4 bronchial gene expression in healthy subjects and whether it impacts AGER and TLR4 gene expression in COPD patients.…”

Regulation of cellular senescence by extracellular matrix during chronic fibrotic diseases

“…In line with this, there is a need to investigate the therapeutic options of inhibiting either the release or activity of ECM DAMPs in fibrosis. DAMPs, have been well characterised in terms of their role in inflammaging, particularly RAGE ligands, which have a well characterised role in innate immune driven pathologies such as COPD, OA and asthma [248][249][250][251]. However, the contribution of DAMPs and the effect of targeting this therapeutically in fibrosis is less well explored.…”

Single-nucleotide polymorphism rs2070600 regulatesAGERsplicing and the sputum levels of the COPD biomarker soluble receptor for advanced glycation end-products

“…Recently, we showed that AGER expression was lower in lung tissue from smokers compared with never-smokers, and that smoking of three cigarettes severely decreased the serum levels of sRAGE within 2 h [ 4 ]. Furthermore, we showed that smokers display increased alternative splicing of AGER into the endogenous soluble splicing form [ 9 ]. Interestingly, we also showed that unlike plasma sRAGE levels, the levels in induced sputum did not correlate with COPD status [ 5 ].…”

“…sRAGE levels were measured in serum and sputum supernatant using ELISA (Human RAGE Duoset ELISA, DY1145; R&D Systems, Minneapolis, MN, USA) according to the manufacturer's protocol. mRNA levels and splicing of AGER was measured in bronchial biopsies as described previously [ 9 ]. In short, mRNA expression analysis was performed using raw counts of AGER and analysed using the R-package DESeq2 [ 9 , 11 ].…”

“…mRNA levels and splicing of AGER was measured in bronchial biopsies as described previously [ 9 ]. In short, mRNA expression analysis was performed using raw counts of AGER and analysed using the R-package DESeq2 [ 9 , 11 ]. For every read spanning an intron in the alignment, the first and last intron base were recorded.…”