Activation of Adenosine A3 Receptor Alleviates TNF-α-Induced Inflammation through Inhibition of the NF-κB Signaling Pathway in Human Colonic Epithelial Cells

Abstract

To investigate the expression of adenosine A3 receptor (A3AR) in human colonic epithelial cells and the effects of A3AR activation on tumor necrosis factor alpha (TNF-α-) induced inflammation in order to determine its mechanism of action in human colonic epithelial cells, human colonic epithelial cells (HT-29 cells) were treated with different concentrations of 2-Cl-IB-MECA prior to TNF-α stimulation, followed by analysis of NF-κB signaling pathway activation and downstream IL-8 and IL-1β production. A3AR mRNA and protein were expressed in HT-29 cells and not altered by changes in TNF-α or 2-Cl-IB-MECA. Pretreatment with 2-Cl-IB-MECA prior to stimulation with TNF-α attenuated NF-κB p65 nuclear translocation as p65 protein decreased in the nucleus of cells and increased in the cytoplasm, inhibited the degradation of IκB-α, and reduced phosphorylated-IκB-α level significantly, compared to TNF-α-only-treated groups. Furthermore, 2-Cl-IB-MECA significantly decreased TNF-α-stimulated IL-8 and IL-1β mRNA expression and secretion, compared to the TNF-α-only treated group. These results confirm that A3AR is expressed in human colonic epithelial cells and demonstrate that its activation has an anti-inflammatory effect, through the inhibition of NF-κB signaling pathway, which leads to inhibition of downstream IL-8 and IL-1β expression. Therefore, A3AR activation may be a potential treatment for gut inflammatory diseases such as inflammatory bowel disease.

An adenosine A3 receptor agonist inhibits DSS-induced colitis in mice through modulation of the NF-κB signaling pathway

“…For example, it can regulate the MEK1/2-ERK1/2 and PI3K/AKT signaling pathways in ameliorating myocardial ischemia/reperfusion injury24 and is involved in the extrinsic cell death pathway in human leukemia cells25. Activation of A3AR by 2-Cl-IB-MECA could alleviate TNF-α-induced inflammation through the inhibition of the NF-κB signaling pathway in human colonic epithelial cells14. However, there are no studies on the effect of 2-Cl-IB-MECA and the molecular mechanism of action of A3AR in murine colitis models in vivo.…”

Assessment of in vivo genotoxicity of citrated-coated silver nanoparticles via transcriptomic analysis of rabbit liver tissue

“…58,59 ADORA3 is one of the G-protein-coupled receptors with a crucial role in intracellular signaling pathways. 60 Various studies have demonstrated its protective role in inflammation-related diseases 61,62 and that downregulation of ADORA3 induces abnormal signal transduction causing tissue damage. Also, SERPINE1 (also known as plasminogen activator inhibitor-1) and VWF, which were upregulated in the presence of cAgNPs, have been reported as diagnostic biomarkers of inflammation, 63 and both genes induce oxidative stress under toxic conditions.…”

Anti-inflammatory Effects of Herbal Preparations STW5 and STW5-II in Cytokine-Challenged Normal Human Colon Cells

“…IL-8 is a powerful neutrophil chemoattractant and activator, whose levels are increased in the mucosa of IBD patients (Mitsuyama et al, 1994). It is also an established inflammatory marker in other cell lines (Ren et al, 2014; Akbari et al, 2015; Noh et al, 2015). Levels of MCP-1 were shown to be increased in IBD (Banks et al, 2003) and were associated with the response toward infliximab therapy (Magnusson et al, 2015).…”