Polymorphisms in alpha 7 nicotinic acetylcholine receptor gene, CHRNA7 , and its partially duplicated gene, CHRFAM7A , associate with increased inflammatory response in human peripheral mononuclear cells

Abstract

The vagus nerve can, via the alpha 7 nicotinic acetylcholine receptor (α7nAChR), regulate inflammation. The gene coding for the α7nAChR, CHRNA7, can be partially duplicated, that is, CHRFAM7A, which is reported to impair the anti‐inflammatory effect mediated via the α7nAChR. Several single nucleotide polymorphisms (SNPs) have been described in both CHRNA7 and CHRFAM7A, however, the functional role of these SNPs for immune responses remains to be investigated. In the current study, we set out to investigate whether genetic variants of CHRNA7 and CHRFAM7A can influence immune responses. By investigating data available from the Swedish SciLifeLab SCAPIS Wellness Profiling (S3WP) study, in combination with droplet digital PCR and freshly isolated PBMCs from the S3WP participants, challenged with lipopolysaccharide (LPS), we show that CHRNA7 and CHRFAM7A are expressed in human PBMCs, with approximately four times higher expression of CHRFAM7A compared with CHRNA7. One SNP in CHRFAM7A, rs34007223, is positively associated with hsCRP in healthy individuals. Furthermore, gene ontology (GO)‐terms analysis of plasma proteins associated with gene expression of CHRNA7 and CHRFAM7A demonstrated an involvement for these genes in immune responses. This was further supported by in vitro data showing that several SNPs in both CHRNA7 and CHRFAM7A are significantly associated with cytokine response. In conclusion, genetic variants of CHRNA7 and CHRFAM7A alters cytokine responses. Furthermore, given that CHRFAM7A SNP rs34007223 is associated with inflammatory marker hsCRP in healthy individuals suggests that CHRFAM7A may have a more pronounced role in regulating inflammatory processes in humans than previously been recognized.

Alpha7 nicotinic acetylcholine receptor agonist PHA 568487 dampens inflammation in PBMCs from patients with newly discovered coronary artery disease

“…For the in vitro stimulations, PBMCs were seeded at a concentration of 2×10 5 cells/well in triplicates and stimulated with LPS (8.33 ng/ml, List Biological Laboratories Inc., Campbell, USA) with/without α7nAChR agonist PHA568487 (83 μM) for 4 hours as previously described 2 . Supernatants were analyzed using the Bio-Plex Pro Human Cytokine Panel 17-plex assay (Bio Rad Laboratories, Inc. Hercules, USA) following the manufacturer’s protocol.…”

“…Following activation of the cholinergic anti-inflammatory pathway, or via direct stimulation with agonists, the α7nAChR can suppress the release of pro-inflammatory cytokines from immune cells 1 . In humans, the α7nAChR is expressed both in peripheral blood mononuclear cells (PBMCs) 2 and in atherosclerotic plaques 3 . Stimulation of the α7nAChR reduces the inflammatory response in whole blood from healthy donors 4 .…”

Alpha7 Nicotinic Acetylcholine Receptor Agonist PHA 568487 Does Not Affect Cardiac Function nor Myocardial Infarct Size in the Permanent Occlusion Model

“…Reverse transcription was performed using the High-capacity cDNA Reverse Transcription Kit (Applied Biosystems, Waltham, MA) according to the manufacturer's protocol. The expression of the α7nAChR was determined with droplet digital pcr (ddpcr) utilizing EvaGreen (Bio-Rad Laboratories, CA, USA) as previously described [28]. Samples were analyzed in the QX200 Droplet Reader (Bio-Rad Laboratories, CA, USA) and the results, including positive and negative droplets, analyzed with QuantaSoft Analysis Pro™ (Bio-Rad Laboratories).…”

Alpha 7 Nicotinic Acetylcholine Receptor Agonist PHA 568487 Reduces Acute Inflammation but Does Not Affect Cardiac Function or Myocardial Infarct Size in the Permanent Occlusion Model

“…Reverse transcription was performed using the High-capacity cDNA Reverse Transcription Kit (Applied Biosystems, Waltham, MA, USA), according to the manufacturer's protocol. The expression of the α7nAChR gene, Chrna7, was determined with droplet digital PCR (ddPCR) utilizing EvaGreen (Bio-Rad Laboratories, Hercules, CA, USA) as previously described [29]. Samples were analyzed in the QX200 Droplet Reader (Bio-Rad Laboratories) and the results, including positive and negative droplets, analyzed with QuantaSoft Analysis Pro™ (Bio-Rad Laboratories).…”