The muscarinic antagonist gallamine induces proliferation of airway smooth muscle cells regardless of the cell phenotype

Pharmaceutical Assessment Suggests Locomotion Hyperactivity in Zebrafish Triggered by Arecoline Might Be Associated with Multiple Muscarinic Acetylcholine Receptors Activation

Arecoline is one of the nicotinic acid-based alkaloids, which is found in the betel nut. In addition to its function as a muscarinic agonist, arecoline exhibits several adverse effects, such as inducing growth retardation and causing developmental defects in animal embryos, including zebrafish, chicken, and mice. In this study, we aimed to study the potential adverse effects of waterborne arecoline exposure on zebrafish larvae locomotor activity and investigate the possible mechanism of the arecoline effects in zebrafish behavior. The zebrafish behavior analysis, together with molecular docking and the antagonist co-exposure experiment using muscarinic acetylcholine receptor antagonists were conducted. Zebrafish larvae aged 96 h post-fertilization (hpf) were exposed to different concentrations (0.001, 0.01, 0.1, and 1 ppm) of arecoline for 30 min and 24 h, respectively, to find out the effect of arecoline in different time exposures. Locomotor activities were measured and quantified at 120 hpf. The results showed that arecoline caused zebrafish larvae locomotor hyperactivities, even at a very low concentration. For the mechanistic study, we conducted a structure-based molecular docking simulation and antagonist co-exposure experiment to explore the potential interactions between arecoline and eight subtypes, namely, M1a, M2a, M2b, M3a, M3b, M4a, M5a, and M5b, of zebrafish endogenous muscarinic acetylcholine receptors (mAChRs). Arecoline was predicted to show a strong binding affinity to most of the subtypes. We also discovered that the locomotion hyperactivity phenotypes triggered by arecoline could be rescued by co-incubating it with M1 to M4 mAChR antagonists. Taken together, by a pharmacological approach, we demonstrated that arecoline functions as a highly potent hyperactivity-stimulating compound in zebrafish that is mediated by multiple muscarinic acetylcholine receptors.

Long Noncoding RNA COPDA1 Promotes Airway Smooth Muscle Cell Proliferation in Chronic Obstructive Pulmonary Disease

Abnormal expression of long noncoding RNAs (lncRNAs) has been confirmed to be associated with many diseases, including chronic obstructive pulmonary disease (COPD). To gain better understanding of the mechanism of COPD, we investigated the lncRNA and mRNA profiles in the lung tissue of patients with COPD. According to the analysis, one of the significantly different lncRNAs, COPDA1, might participate in the occurrence and development of COPD. Lung tissues were collected from nonsmokers, smokers, or smokers with COPD for RNA sequencing. Bioinformatic analysis and cell experiments were used to define the function of COPDA1, and the effects of COPDA1 on intracellular Ca²⁺ concentration and cell proliferation were examined after knockdown or overexpression of COPDA1. A number of variations of lncRNAs were found in the comparison of nonsmokers, smokers, and smokers with COPD. GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analyses indicated that smoking was involved in the activation of cytokines and the cell cycle, which is associated with COPD. According to the lncRNA-mRNA-coexpressing network and enrichment analysis, COPDAz1 and one of its target genes, MS4A1 (membrane-spanning 4-domains family, subfamily A) were investigated, and we discovered that the expression of MS4A1 was closely associated with lncRNA COPDA1 expression in human bronchial smooth muscle cells (HBSMCs). Further study showed that lncRNA COPDA1 upregulated the expression of MS4A1 to increase store-operated calcium entry in the HBSMCs, resulting in the promotion of the proliferation of smooth muscle cells as well as of airway remodeling. COPDA1 might be involved in the regulation of certain signaling pathways in COPD, might promote the proliferation of HBSMCs, and might also be involved in facilitating airway remodeling.

MiRNA-192-5p attenuates airway remodeling and autophagy in asthma by targeting MMP-16 and ATG7

Asthma is a chronic lung inflammatory disease with high incidence. MicroRNA-192-5p (miR-192-5p) was down-regulated in asthmatics. However, the role of miR-192-5p in asthma is still unclear. In current study, in vitro, the overexpression of miR-192-5p, matrix metalloproteinase (MMP)-16 and autophagy related 7 (ATG7) was conducted in airway smooth muscle cells (ASMCs). We found that miR-192-5p suppressed cell proliferation, and decreased MMP-16 and ATG7 expression. MMP-16 and ATG7 promoted cell proliferation, and further alleviated the down-regulation of miR-192-5p on proliferation of ASMCs. in vivo, miR-192-5p was down-regulated in asthma mice, and involved in improvement of asthma mice. MiR-192-5p was demonstrated to alleviate inflammation in asthma mice, including decreasing the level of ovalbumin (OVA)-specific IgE, interleukin (IL)-4, IL-5, IL-13, iNOS and COX-2. Moreover, the attenuation of airway remodeling induced by miR-192-5p in asthma mice were expressed by the reduction of fibroblast growth factor-23 (FGF-23) level, decrease in concentrations of MMP-2 and MMP-9 as well as down-regulation of collagen I deposition. Further, miR-192-5p also caused the suppression of autophagy in asthma mice, exhibiting a decrease in LC3II/I, beclin-1 and ATG7, and an increase in p62. Importantly, MMP-16 and ATG7 were confirmed to be targets of miR-192-5p. Therefore, our results indicate that miRNA-192-5p may attenuate airway remodeling and autophagy in asthma via targeting MMP-16 and ATG7.