Research progress in the mechanism of calcium ion on contraction and relaxation of airway smooth muscle cells

Association of dietary calcium intake with chronic bronchitis and emphysema

OBJECTIVE

Chronic bronchitis and emphysema (CBE) are two main types of chronic obstructive pulmonary disease (COPD). We aimed to investigate the relationship between dietary calcium intake and the risk of CBE.

METHODS

Data were obtained from the National Health and Nutrition Examination Survey (NHANES) 2007-2012. The ratio of forced expiratory volume in 1 s (FEV1) to forced vital capacity (FVC) < 0.7 was used to define airflow obstruction. Multivariate logistic regression was performed to assess the effects of dietary calcium intake on CBE and airflow obstruction. Dietary calcium intake was divided into quartiles, with the lowest quartile set as the reference group. Linear regression models were applied to explore the association between dietary calcium intake and lung function.

RESULTS

A total of 10,143 participants were enrolled in the study, including 594 CBE and 9549 non-CBE individuals. The average dietary calcium intake was 908.5 ± 636.1 mg/day in the CBE group and 951.9 ± 599.7 mg/day in the non-CBE group. When using the lowest quartile of dietary calcium intake as a reference, the second, third, and fourth quartiles reduced the risk of CBE by 0.803 [95% confidence interval (CI): 0.802-0.804; P < 0.001], 0.659 (95% CI: 0.659-0.660; P < 0.001) and 0.644 (95% CI: 0.643-0.644; P < 0.001) times, respectively. Increased dietary calcium intake was correlated with reduced risk of airflow obstruction. Dietary calcium intake positively predicts FEV1 (β = 0.225, P < 0.001) and FVC (β = 0.232, P < 0.001).

CONCLUSION

Increased intake of dietary calcium may contribute to higher lung function, a lower risk of CBE and airflow obstruction. Since the cross-sectional design makes it difficult to determine a causal relationship, further research is needed to confirm these findings and explore the underlying mechanisms.

Repeated-Dose Toxicity of Lauric Acid and Its Preventive Effect Against Tracheal Hyper-Responsiveness in Wistar Rats with Possible In Silico Molecular Targets

BACKGROUND/OBJECTIVES

Lauric acid (LA), a medium-chain fatty acid, is a promising drug for asthma treatment. This study evaluated the toxicity of repeated doses and the effect of LA on pulmonary ventilation and tracheal reactivity in asthmatic Wistar rats and identified possible molecular targets of LA action in silico.

METHODS

The rats were divided into control (CG) and LA-treated groups at 100 mg/kg (AL100G) for toxicity analysis. Pulmonary ventilation and tracheal reactivity were assessed in the control (CG), asthmatic (AG), asthmatic treated with LA at 25, 50, or 100 mg/kg (AAL25G, AAL50G, and AAL100G), and dexamethasone-treated groups (ADEXAG).

RESULTS

The results showed that LA at a dose of 100 mg/kg did not cause death or toxicity. A pulmonary ventilation analysis indicated that AG had reduced minute volume, which was prevented in AAL25G. LA at all doses prevented carbachol-induced tracheal hyper-responsiveness and reduced the relaxing effect of aminophylline, as observed in AG. An in silico analysis revealed that LA had a good affinity for nine proteins (β2-adrenergic receptor, CaV, BKCa, KATP, adenylyl cyclase, PKG, eNOS, iNOS, and COX-2).

CONCLUSIONS

LA at 100 mg/kg has low toxicity, prevents hyper-responsiveness in an asthma model in rats, and acts as a multitarget compound with a good affinity for proteins related to airway hyper-responsiveness.

The Role of Trace Elements in COPD: Pathogenetic Mechanisms and Therapeutic Potential of Zinc, Iron, Magnesium, Selenium, Manganese, Copper, and Calcium

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a progressive, inflammatory airway disorder characterized by a gradual decline in lung function and increased oxidative stress. Both oxidative stress and inflammation are central to its pathophysiology, with trace elements such as zinc, copper, iron, manganese, magnesium, selenium, and calcium playing key roles in various cellular processes.

OBJECTIVE

This article reviews the role of trace elements in COPD, focusing on their involvement in disease pathogenesis and their therapeutic potential. Specifically, we examine the effects of zinc, copper, iron, magnesium, manganese, selenium, and calcium in COPD.

METHODS

We performed a comprehensive narrative review of the literature across databases including PubMed, Web of Science, Cochrane Library, and Google Scholar, identifying studies that explore the therapeutic effects of trace elements in COPD. The studies included in the review consisted of cohort analyses, randomized controlled trials, and clinical investigations.

RESULTS

Zinc, copper, iron, magnesium, manganese, selenium, and calcium are critical to both the pathophysiology and management of COPD. These trace elements contribute to the regulation of inflammation, the modulation of oxidative stress, and the maintenance of lung function. Zinc and copper, for instance, reduce oxidative stress and modulate immune responses, while iron is essential for oxygen transport. Magnesium, manganese, selenium, and calcium are vital for muscle function, respiratory performance, reducing inflammation, and improving pulmonary function.

CONCLUSIONS

The minerals zinc, copper, iron, magnesium, manganese, selenium, and calcium may contribute to beneficial effects as part of the standard therapeutic management of COPD. Maintaining optimal levels of these trace elements may support the regulation of inflammatory processes, a reduction in oxidative stress, and an improvement in the pulmonary function. However, further clinical research is necessary to confirm their efficacy and establish safe dosage recommendations in COPD treatment.

Characterization of PDGF-Induced Subcellular Calcium Regulation through Calcium Channels in Airway Smooth Muscle Cells by FRET Biosensors

The homeostasis of cellular calcium is fundamental for many physiological processes, while the calcium levels remain inhomogeneous within cells. During the onset of asthma, epithelial and inflammatory cells secrete platelet-derived growth factor (PDGF), inducing the proliferation and migration of airway smooth muscle (ASM) to the epidermal layer, narrowing the airway. The regulation of ASM cells by PDGF is closely related to the conduction of calcium signals. In this work, we generated subcellular-targeted FRET biosensors to investigate calcium regulation in the different compartments of ASM cells. A PDGF-induced cytoplasmic calcium [Ca2+]C increase was attributed to both extracellular calcium influx and endoplasmic reticulum (ER) calcium [Ca2+]ER release, which was partially regulated by the PLC-IP3R pathway. Interestingly, the removal of the extracellular calcium influx led to inhibited ER calcium release, likely through inhibitory effects on the calcium-dependent activation of the ER ryanodine receptor. The inhibition of the L-type calcium channel on the plasma membrane or the SERCA pump on the ER resulted in both reduced [Ca2+]C and [Ca2+]ER from PDGF stimulation, while IP3R channel inhibition led to reduced [Ca2+]C only. The inhibited SERCA pump caused an immediate [Ca2+]C increase and [Ca2+]ER decrease, indicating active calcium exchange between the cytosol and ER storage in resting cells. PDGF-induced calcium at the outer mitochondrial membrane sub-region showed a similar regulatory response to cytosolic calcium, not influenced by the inhibition of the mitochondrial calcium uniporter channel. Therefore, our work identifies calcium flow pathways among the extracellular medium, cell cytosol, and ER via regulatory calcium channels. Specifically, extracellular calcium flow has an essential function in fully activating ER calcium release.

Effects of Shiwei Longdanhua formula on LPS induced airway mucus hypersecretion, cough hypersensitivity, oxidative stress and pulmonary inflammation

Shiwei Longdanhua Granule (SWLDH) is a classic Tibetan medicine (TM) ranking in the top 20 Chinese patent medicines in prescription rate to treat respiratory diseases like pneumonia, acute and chronic tracheobronchitis, acute exacerbation of COPD and bronchial asthma in solution of inflammation, cough and phlegm obstruction in clinical practice. However, its systematic pharmacological mechanisms have not been elucidated yet. Here, we studied the therapeutic efficacy of SWLDH in treatment of acute respiratory diseases in BALB/c mice by comprehensive analysis of airway inflammation, oxidative stress, mucus hypersecretion, cough hypersensitivities and indicators associated with the development of chronic diseases. Our results show that SWLDH might exhibit its inhibitory effects on pulmonary inflammation by interference with arachidonic acid (AA) metabolism pathways. Oxidative stress that highly related to the degree of tissue injury could be alleviated by enhancing the reductive activities of glutathione redox system, thioredoxin system and the catalytic activities of catalase and superoxide dismutase (SOD) after SWLDH treatment. In addition, SWLDH could significantly abrogate the mucus hypersecretion induced bronchiole obstruction by inactivate the globlet cells and decrease the secretion of gel-forming mucins (MUC5AC and MUC5B) under pathological condition, demonstrating its mucoactive potency. SWLDH also showed reversed effects on the release of neuropeptides that are responsible for airway sensory hypersensitivity. Simultaneously observed inhibition of calcium influx, reduction in in vivo biosynthesis of acetylcholine and the recovery of the content of cyclic adenosine monophosphate (cAMP) might collaboratively contribute to cause airway smooth muscle cells (ASMCs) relexation. These findings indicated that SWLDH might exhibited antitussive potency via suppression of the urge to cough and ASMCs contraction. Moreover, SWLDH might affect airway remodeling. We found SWLDH could retard the elevation of TGF-β1 and α-SMA, which are important indicators for hyperplasia and contraction during the progression of the chronic airway inflammatory diseases like COPD and asthma.

AKG/OXGR1 promotes skeletal muscle blood flow and metabolism by relaxing vascular smooth muscle

In response to contraction during exercise, skeletal muscle growth and metabolism are dynamically regulated by nerve action, blood flow, and metabolic feedback. α-Ketoglutarate (AKG), a bioactive intermediate in the tricarboxylic acid cycle released during exercise, has been shown to promote skeletal muscle hypertrophy. However, the underlying mechanism of AKG in regulating skeletal muscle development and metabolism is still less known. 2-Oxoglutarate receptor 1 (OXGR1), the endogenous AKG receptor, is found to be distributed in the vascular smooth muscle (VSM) of skeletal muscles. OXGR1 knockout results in skeletal muscle atrophy, accompanied by decreased expression of myosin heavy chain I (MyHC I), capillary density, and endurance exercise capacity. Furthermore, the study found that dietary AKG supplementation increased mice endurance exercise distance, MyHC I/MyHC IIb ratio, arteriole, and capillary densities in skeletal muscle. Meanwhile, acute AKG administration gradually increased the blood flow in the lower limbs. Further, by using OXGR1 global knockout and OXGR1 VSM-specific (MYH11-Cre × OXGR1-FloxP) knockdown models, we found that OXGR1 in VSM is essential for AKG-induced improvement of skeletal muscle performances. According to the in vitro study, AKG expanded the cell area in VSM with a decreased intracellular pH by OXGR1. Our results demonstrated a novel role of AKG/OXGR1 in VSM of skeletal muscle to regulate blood flow and then enhance slow muscle fiber conversion and capillarization. These findings provide a theoretical basis for the AKG/OXGR1 signaling pathway to maintain human muscle function and improve meat production and livestock and poultry meat quality.

Sport Performance and Manual Therapies: A Review on the Effects on Mitochondrial, Sarcoplasmatic and Ca2+ Flux Response

The present narrative review aims to highlight the possible effects manual therapies could have on cells and mitochondria, as these effects could improve athletic performance management. To this aim, this review summarizes the relationship between mechanical stimulation, with a special focus on physical activity, and cell response based on the most recent mechanobiology findings. Mechanobiology analyzes how cells respond to mechanical stressors coming from the environment. Indeed, endogenous (e.g., blood pressure, heartbeat and gastrointestinal motility) and exogenous (e.g., physical activity and manual therapies) stimuli can induce biochemical and epigenetic modifications that alter protein synthesis with heavy consequences on cell behavior. Mechanical stress can also influence mitochondrial behavior (i.e., biogenesis, autophagy, fusion, fission and energy production), sarcoplasmic response and calcium ion (Ca²⁺) flux. Since manual therapies have been shown to affect the extracellular matrix, which represents a primary source of mechanical stress that may alter both the cytoskeleton and mitochondrial metabolism, it is conceivable manual therapies could also affect cellular and mitochondrial behavior. Lastly, by suggesting possible directions for future laboratory and clinical studies, the authors expect this review to inspire further research on how manual therapies could affect bioenergetic metabolism and, thus, athletic performance.