Tumor necrosis factor receptor 2 as a possible marker of COPD in smokers and ex-smokers

The AGE-RAGE Axis and RAGE Genetics in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a heterogeneous group of lung diseases limiting the airflow due to narrowing of airways, chronic bronchitis and emphysema that leads to difficulties in breathing. Chronic inflammation is another important characteristic of COPD which leads to immune cell infiltration and helps in the alveolar destruction. Pathology of COPD is driven by various environmental and genetic factors. COPD is mainly associated with the inhalation of toxic agents mainly the cigarette smoke. Receptor for advanced glycation end products (RAGE) has emerged as a pattern recognition receptor and is a multiligand receptor expressed moderately in various cells, tissues and highly in the lungs throughout life. RAGE recognizes various ligands produced by cigarette smoke and its role has been implicated in the pathogenesis of COPD. RAGE ligands have been reported to accumulate in the lungs of patients with COPD. RAGE is a membrane receptor but its truncated form i.e. soluble RAGE (sRAGE) mainly functions as a contender of RAGE and inhibits various RAGE dependent cell signalling. Among the various ligands of RAGE, advanced glycation end products (AGEs) are majorly linked with COPD. Accumulated AGE triggers downstream RAGE-AGE axis in COPD. Moreover, RAGE genetics has long been known to play a vital role in the pathology of various airway diseases including COPD and this gene contains an associated locus. A reliable biomarker is needed for the management of this disease. sRAGE has an inverse correlation with the RAGE showed its importance as a valuable marker in COPD. This review is focused on the role of RAGE, sRAGE, RAGE axis and RAGE genetics in COPD.

Peli1 induction impairs cardiac microvascular endothelium through Hsp90 dissociation from IRE1α

Ameliorating cardiac microvascular injury is the most effective means to mitigate diabetes-induced cardiovascular complications. Inositol-requiring 1α (IRE1α), a sensor of endoplasmic reticulum stress, is activated by Toll like receptors (TLRs), and then promotes cardiac microvascular injury. Peli1 is a master regulator of TLRs and activates IRE1α. This study aims to investigate whether Peli1 in endothelial cells promotes diabetes-induced cardiac microvascular injury through activating IRE1α. Here we found that Peli1 was markedly up-regulated in cardiac endothelial cells of both diabetic mice and in AGEs-treated cardiac microvascular endothelial cells (CMECs). Peli1 deficiency in endothelial cells significantly alleviated diabetes-induced cardiac microvascular permeability, promoted microvascular regeneration, and suppressed apoptosis, accompanied by the attenuation of adverse cardiac remodeling. Furthermore, Peli1 deletion in CMECs ameliorated AGEs-induced damages in vitro. We identified heat shock protein 90 (Hsp90) as a potential binding partner for Peli1, and the Ring domain of Peli1 directly bound with Hsp90 to enhance IRE1α phosphorylation. Our study suggests that blocking Peli1 in endothelial cells may protect against diabetes-induced cardiac microvascular injury by restraining ER stress.

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

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.

LncRNAs NR-026690 and ENST00000447867 are upregulated in CD4+ T cells in patients with acute exacerbation of COPD

Objective

The aim of the study was to determine the expression profile of long noncoding RNAs (lncRNAs) in CD4⁺ T cells from COPD patients and explore the clinical value of the lncRNAs.

Methods

First, microarray analysis was performed. Differentially expressed lncRNAs were validated by quantitative real-time reverse transcription-PCR (qRT-PCR) in samples from 56 patients with acute exacerbations of COPD (AECOPD), 56 patients with stable COPD, and 35 healthy controls. Meanwhile, the clinical value was tested by receiver operating characteristic curve analysis. The functions of lncRNAs were analyzed by the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes database. The potential target genes that might be regulated by NR-026690 and ENST00000447867 were identified by the lncRNA-mRNA network and competing endogenous RNA network. The transcriptional expression level of rap guanine nucleotide exchange factor 3 (RAPGEF3) was tested by qRT-PCR. The correlation of the expression between NR-026690, ENST00000447867, and RAPGEF3 was analyzed by Spearman's correlation test.

Results

We found that the relative expression levels of ENST00000447867 and NR-026690 in the CD4⁺ T cells of AECOPD patients were significantly higher than in the stable COPD patients and control subjects by microarray and qRT-PCR validation. The transcriptional expression level of RAPGEF3 in the CD4⁺ T cells was significantly higher in the AECOPD group compared to the control group (P<0.01) and the stable COPD group (P<0.05). RAPGEF3 expression was positively associated with NR-026690 (r=0.4925, P<0.01) and ENST00000447867 (r=0.4065, P<0.01).

Conclusion

NR-026690 and ENST00000447867 might be potential biomarkers for COPD. They might affect RAPGEF3 as miRNA sponges to regulate COPD development.

Identification and functional characterization of grass carp (Ctenopharyngodon idella) tumor necrosis factor receptor 2 and its soluble form with potentiality for targeting inflammation

Tumor necrosis factor-alpha (TNF-α) signals through two distinct cell surface receptors, TNFR1 and TNFR2 in mammals. In the present study, grass carp Tnfr2 (gcTnfr2) was isolated and characterized. Sequence alignment and phylogenetic analysis suggested that gcTnfr2 was a homolog of goldfish and zebrafish Tnfr2. Tissue distribution assay showed gctnfr2 transcripts were expressed in all examined tissues similar to gctnfr1. To functionally characterize the newly cloned molecule, gcTnfr2 was overexpressed in COS7 cell lines and it showed the ability to mediate the recombinant grass carp Tnf (rgcTnf)-α-triggered NF-κΒ activity and gcil1b promoter activity, clarifying its role in mediating Tnf-α signaling. The recombinant soluble form of gcTnfr2 (rgcsTnfr2) was prepared and it was able to interact with rgcTnf-α with higher affinity than that of rgcsTnfr1. Moreover, grass carp soluble Tnfr2 (gcsTnfr2) were detected in the culture medium of grass carp head kidney leukocytes (HKLs) and heat-inactivated A. hydrophila challenge significantly induced its production, indicating involvement of gcsTnfr2 in inflammation response. In agreement with this notion, rgcsTnfr2 effectively antagonized the effect of rgcTnf-α on il1b mRNA expression in HKLs, suggesting anti-Tnf-α property of gcsTnfr2. To strengthen the anti-inflammatory role of soluble Tnfr2, bacteria were injected intraperitoneally in grass carp followed by rgcsTnfr2. Hematoxylin-eosin (HE) staining of head kidney, spleen and intestine showed that rgcsTnfr2 could significantly improve infection-induced histopathological changes. These results functionally identified gcTnfr2 and its soluble form, particularly highlighting the role of gcsTnfr2 against Tnf-α-triggered inflammatory signaling. In this line, rgcsTnfr2 displayed anti-inflammatory potentiality during infection, thereby providing a powerful mediator of inflammation control in fish.