Aerobic exercise ameliorates particulate matter-induced lung injury in aging rats

Aerobic exercise training engages the canonical wnt pathway to improve pulmonary function and inflammation in COPD

BACKGROUND

We studied whether the exercise improves cigarette smoke (CS) induced chronic obstructive pulmonary disease (COPD) in mice through inhibition of inflammation mediated by Wnt/β-catenin-peroxisome proliferator-activated receptor (PPAR) γ signaling.

METHODS

Firstly, we observed the effect of exercise on pulmonary inflammation, lung function, and Wnt/β-catenin-PPARγ. A total of 30 male C57BL/6J mice were divided into the control group (CG), smoke group (SG), low-intensity exercise group (LEG), moderate-intensity exercise group (MEG), and high-intensity exercise group (HEG). All the groups, except for CG, underwent whole-body progressive exposure to CS for 25 weeks. Then, we assessed the maximal exercise capacity of mice from the LEG, MEG, and HEG, and performed an 8-week treadmill exercise intervention. Then, we used LiCl (Wnt/β-catenin agonist) and XAV939 (Wnt/β-catenin antagonist) to investigate whether Wnt/β-catenin-PPARγ pathway played a role in the improvement of COPD via exercise. Male C57BL/6J mice were randomly divided into six groups (n = 6 per group): CG, SG, LiCl group, LiCl and exercise group, XAV939 group, and XAV939 and exercise group. Mice except those in the CG were exposed to CS, and those in the exercise groups were subjected to moderate-intensity exercise training. All the mice were subjected to lung function test, lung histological assessment, and analysis of inflammatory markers in the bronchoalveolar lavage fluid, as well as detection of Wnt1, β-catenin and PPARγ proteins in the lung tissue.

RESULTS

Exercise of various intensities alleviated lung structural changes, pulmonary function and inflammation in COPD, with moderate-intensity exercise exhibiting significant and comprehensive effects on the alleviation of pulmonary inflammation and improvement of lung function. Low-, moderate-, and high-intensity exercise decreased β-catenin levels and increased those of PPARγ significantly, and only moderate-intensity exercise reduced the level of Wnt1 protein. Moderate-intensity exercise relieved the inflammation aggravated by Wnt agonist. Wnt antagonist combined with moderate-intensity exercise increased the levels of PPARγ, which may explain the highest improvement of pulmonary function observed in this group.

CONCLUSIONS

Exercise effectively decreases COPD pulmonary inflammation and improves pulmonary function. The beneficial role of exercise may be exerted through Wnt/β-catenin-PPARγ pathway.

Treadmill training improves lung function and inhibits alveolar cell apoptosis in spinal cord injured rats

Secondary lung injury after SCI is a major cause of patient mortality, with apoptosis playing a key role. This study aimed to explore the impact of treadmill training and miR145-5p on the MAPK/Erk signaling pathway and apoptosis in rats with complete SCI. SD rats were used to establish T10 segmental complete SCI models and underwent treadmill training 3, 7, or 14 days postinjury. Various techniques including arterial blood gas analysis, lung wet/dry weight ratio, HE staining, immunofluorescence staining, immunohistochemical staining, qRT-PCR, and Western blotting were employed to assess alterations in lung function and the expression levels of crucial apoptosis-related factors. In order to elucidate the specific mechanism, the impact of miR145-5p on the MAPK/Erk pathway and its role in apoptosis in lung cells were confirmed through miR145-5p overexpression and knockdown experiments. Following spinal cord injury (SCI), an increase in apoptosis, activation of the MAPK/Erk pathway, and impairment of lung function were observed in SCI rats. Conversely, treadmill training resulted in a reduction in alveolar cell apoptosis, suppression of the MAPK/Erk pathway, and enhancement of lung function. The gene MAP3K3 was identified as a target of miR145-5p. The influence of miR145-5p on the MAPK/Erk pathway and its impact on apoptosis in alveolar cells were confirmed through the manipulation of miR145-5p expression levels. The upregulation of miR145-5p in spinal cord injury (SCI) rats led to a reduction in MAP3K3 protein expression within lung tissues, thereby inhibiting the MAPK/Erk signaling pathway and decreasing apoptosis. Contrarily, rats with miR145-5p knockdown undergoing treadmill training exhibited an increase in miR145-5p expression levels, resulting in the inhibition of MAP3K3 protein expression in lung tissues, suppression of the MAPK/Erk pathway, and mitigation of lung cell apoptosis. Ultimately, the findings suggest that treadmill training may attenuate apoptosis in lung cells post-spinal cord injury by modulating the MAP3K3 protein through miR145-5p to regulate the MAPK/Erk signaling pathway.

High-intensity intermittent training ameliorates methotrexate-induced acute lung injury

Inflammation and oxidative stress are recognized as two primary causes of lung damage induced by methotrexate, a drug used in the treatment of cancer and immunological diseases. This drug triggers the generation of oxidants, leading to lung injury. Given the antioxidant and anti-inflammatory effects of high-intensity intermittent training (HIIT), our aim was to evaluate the therapeutic potential of HIIT in mitigating methotrexate-induced lung damage in rats. Seventy male Wistar rats were randomly divided into five groups: CTL (Control), HIIT (High-intensity intermittent training), ALI (Acute Lung Injury), HIIT+ALI (pretreated with HIIT), and ALI + HIIT (treated with HIIT).HIIT sessions were conducted for 8 weeks. At the end of the study, assessments were made on malondialdehyde, total antioxidant capacity (TAC), superoxide dismutase (SOD), glutathione peroxidase (Gpx), myeloperoxidase (MPO), interleukin 10 (IL-10), tumor necrosis factor-alpha (TNF-α), gene expression of T-bet, GATA3, FOXP3, lung wet/dry weight ratio, pulmonary capillary permeability, apoptosis (Caspase-3), and histopathological indices.Methotrexate administration resulted in increased levels of TNF-α, MPO, GATA3, caspase-3, and pulmonary edema indices, while reducing the levels of TAC, SOD, Gpx, IL-10, T-bet, and FOXP3. Pretreatment and treatment with HIIT reduced the levels of oxidant and inflammatory factors, pulmonary edema, and other histopathological indicators. Concurrently, HIIT increased the levels of antioxidant and anti-inflammatory factors.

Exercise training inhibits macrophage-derived IL-17A-CXCL5-CXCR2 inflammatory axis to attenuate pulmonary fibrosis in mice exposed to silica

Exposure to crystalline silica leads to health effects beyond occupational silicosis. Exercise training's potential benefits on pulmonary diseases yield inconsistent outcomes. In this study, we utilized experimental silicotic mice subjected to exercise training and pharmacological interventions, including interleukin-17A (IL-17A) neutralizing antibody or clodronate liposome for macrophage depletion. Findings reveal exercise training's ability to mitigate silicosis progression in mice by suppressing scavenger receptor B (SRB)/NOD-like receptor thermal protein domain associated protein 3 (NLRP3) and Toll-like receptor 4 (TLR4) pathways. Macrophage-derived IL-17A emerges as primary source and trigger for silica-induced pulmonary inflammation and fibrosis. Exercise training effectively inhibits IL-17A-CXC motif chemokine ligand 5 (CXCL5)-Chemokine (C-X-C motif) Receptor 2 (CXCR2) axis in silicotic mice. Our study evidences exercise training's potential to reduce collagen deposition, preserve elastic fibers, slow pulmonary fibrosis advancement, and enhance pulmonary function post silica exposure by impeding macrophage-derived IL-17A-CXCL5-CXCR2 axis.

Aerobic exercise alleviates ventilator-induced lung injury by inhibiting NLRP3 inflammasome activation

BACKGROUND

Ventilator-induced lung injury (VILI) is caused by stretch stimulation and other factors related to mechanical ventilation (MV). NOD-like receptor protein 3 (NLRP3), an important innate immune component, is strongly associated with VILI. This study aimed to investigate the effect and mechanisms of aerobic exercise (EX) on VILI.

METHODS

To test the effects of the PKC inhibitor bisindolylmaleimide I on PKC and NLRP3, male C57BL/6 mice (7 weeks old, 19 ~ 23 g) were randomly divided into four groups: control group(C), bisindolylmaleimide I-pretreated group(B), MV group, and bisindolylmaleimide I-pretreated + MV (B + MV) group. The mice were pretreated with bisindolylmaleimide I through intraperitoneal injection (0.02 mg/kg) 1 h before MV. MV was performed at a high tidal volume (30 ml/kg). To explore the ameliorative effect of EX on VILI, the mice were randomly divided into C group, MV group, EX group and EX + MV group and subjected to either MV or 5 weeks of EX training. After ventilation, haematoxylin-eosin (HE) staining and wet/dry weight ratio was used to assess lung pathophysiological changes. PKCɑ, P-PKCɑ, ASC, procaspase-1, caspase-1, pro-IL-1β, IL-1β, NLRP3 and occludin (tight junction protein) expression in lung tissues was determined by Western blotting. The level of IL-6 in alveolar lavage fluid was determined by ELISA.

RESULTS

NLRP3, P-PKCɑ, and PKCɑ levels were inceased in MV group, but bisindolylmaleimide I treatment reversed these changes. Inhibition of PKC production prevented NLRP3 activation. Moreover, MV increased ASC, procaspase-1, caspase-1, pro-IL-1β, and IL1β levels and decreased occludin levels, but EX alleviated these changes. HE staining and lung injury scoring confirmed an absence of obvious lung injury in C group and EX group. Lung injury was most severe in MV group but was improved in EX + MV group. Overall, these findings suggest that MV activates the NLRP3 inflammasome by activating PKCɑ and inducing occludin degradation, while Exercise attenuates NLRP3 inflammasome and PKCɑ activation. Besides, exercise improves cyclic stretch-induced degradation of occludin.

CONCLUSION

PKC activation can increase the level of NLRP3, which can lead to lung injury. Exercise can reduce lung injury by inhibiting PKCɑ and NLRP3 activation. Exercise maybe a potential measure for clinical prevention of VILI.

The underlying mechanism of PM2.5-induced ischemic stroke

Under the background of global industrialization, PM_2.5 has become the fourth-leading risk factor for ischemic stroke worldwide, according to the 2019 GBD estimates. This highlights the hazards of PM_2.5 for ischemic stroke, but unfortunately, PM_2.5 has not received the attention that matches its harmfulness. This article is the first to systematically describe the molecular biological mechanism of PM_2.5-induced ischemic stroke, and also propose potential therapeutic and intervention strategies. We highlight the effect of PM_2.5 on traditional cerebrovascular risk factors (hypertension, hyperglycemia, dyslipidemia, atrial fibrillation), which were easily overlooked in previous studies. Additionally, the effects of PM_2.5 on platelet parameters, megakaryocytes activation, platelet methylation, and PM_2.5-induced oxidative stress, local RAS activation, and miRNA alterations in endothelial cells have also been described. Finally, PM_2.5-induced ischemic brain pathological injury and microglia-dominated neuroinflammation are discussed. Our ultimate goal is to raise the public awareness of the harm of PM_2.5 to ischemic stroke, and to provide a certain level of health guidance for stroke-susceptible populations, as well as point out some interesting ideas and directions for future clinical and basic research.

Remote ischemic preconditioning enhances aerobic performance by accelerating regional oxygenation and improving cardiac function during acute hypobaric hypoxia exposure

Remote ischemic preconditioning (RIPC) may improve exercise performance. However, the influence of RIPC on aerobic performance and underlying physiological mechanisms during hypobaric hypoxia (HH) exposure remains relatively uncertain. Here, we systematically evaluated the potential performance benefits and underlying mechanisms of RIPC during HH exposure. Seventy-nine healthy participants were randomly assigned to receive sham intervention or RIPC (4 × 5 min occlusion 180 mm Hg/reperfusion 0 mm Hg, bilaterally on the upper arms) for 8 consecutive days in phases 1 (24 participants) and phase 2 (55 participants). In the phases 1, we measured the change in maximal oxygen uptake capacity (VO₂max) and muscle oxygenation (SmO₂) on the leg during a graded exercise test. We also measured regional cerebral oxygenation (rSO₂) on the forehead. These measures and physiological variables, such as cardiovascular hemodynamic parameters and heart rate variability index, were used to evaluate the intervention effect of RIPC on the changes in bodily functions caused by HH exposure. In the phase 2, plasma protein mass spectrometry was then performed after RIPC intervention, and the results were further evaluated using ELISA tests to assess possible mechanisms. The results suggested that RIPC intervention improved VO₂max (11.29%) and accelerated both the maximum (18.13%) and minimum (53%) values of SmO₂ and rSO₂ (6.88%) compared to sham intervention in hypobaric hypoxia exposure. Cardiovascular hemodynamic parameters (SV, SVRI, PPV% and SpMet%) and the heart rate variability index (Mean RR, Mean HR, RMSSD, pNN50, Lfnu, Hfnu, SD1, SD2/SD1, ApEn, SampEn, DFA1and DFA2) were evaluated. Protein sequence analysis showed 42 unregulated and six downregulated proteins in the plasma of the RIPC group compared to the sham group after HH exposure. Three proteins, thymosin β4 (Tβ4), heat shock protein-70 (HSP70), and heat shock protein-90 (HSP90), were significantly altered in the plasma of the RIPC group before and after HH exposure. Our data demonstrated that in acute HH exposure, RIPC mitigates the decline in VO₂max and regional oxygenation, as well as physiological variables, such as cardiovascular hemodynamic parameters and the heart rate variability index, by influencing plasma Tβ4, HSP70, and HSP90. These data suggest that RIPC may be beneficial for acute HH exposure.

Amelioration of Ambient Particulate Matter (PM2.5)-Induced Lung Injury in Rats by Aerobic Exercise Training

Ambient particulate matter (PM_2.5), as an inflammation-inducing factor, increases the prevalence of lung injury. The aim of this study was to examine the protective effect and mechanism of aerobic exercise on PM_2.5 exposure-induced lung injury. Forty Wistar rats were randomly divided into four groups: sedentary+PM_2.5 exposure, exercise+PM_2.5 exposure, sedentary, and exercise groups. All rats in the exercise-related groups underwent 8-week aerobic interval treadmill training (5daysweek⁻¹, 1hday⁻¹). PM-exposed rats were exposed to ambient PM_2.5 (6h day⁻¹) for 3weeks after the 8-week exercise intervention. Then, ventilation function, histopathological changes, and inflammation responses of pulmonary tissue were examined. Results showed that PM_2.5 exposure induced lung injury as manifested by decreased pulmonary function, abnormal histopathological changes, and increased pro-inflammatory cytokine levels (tumor necrosis factor-α and Interleukin-1α). Aerobic exercise alleviated the airway obstruction, reduced respiratory muscle strength, bronchial mucosal exfoliation, ultrastructure damage, and inflammatory responses induced by PM_2.5 in exercise-related groups. The benefits of exercise were related with the downregulation of p38-mitogen-activated protein kinase (MAPK), and the subsequent inhibition of the pathways of the cyclooxygenase 2 (COX-2) product, prostaglandin E₂ (PGE₂). Thus, pre-exercise training may be an effective way to protect against PM_2.5-induced lung inflammatory injury in rats.

HSP70 as a biomarker of the thin threshold between benefit and injury due to physical exercise when exposed to air pollution

Physical exercise has acute and chronic effects on inflammatory balance, metabolic regulation, and redox status. Exercise-induced adaptations are mediated by enhanced 70-kDa heat shock protein (HSP70) levels and an improved heat shock response (HSR). Therefore, exercise could be useful against disease conditions [obesity, diabetes mellitus (DM), and exposure to atmospheric pollutants] marked by an impaired HSR. However, exercise performed by obese or diabetic subjects under pollution conditions might also be dangerous at certain intensities. Intensity correlates with an increase in HSP70 levels during physical exercise until a critical point at which the effort becomes harmful and impairs the HSR. Establishing a unique biomarker able to indicate the exercise intensity on metabolism and cellular fatigue is essential to ensure adequate and safe exercise recommendations for individuals with obesity or DM who require exercise to improve their metabolic status and live in polluted regions. In this review, we examined the available evidence supporting our hypothesis that HSP70 could serve as a biomarker for determining the optimal exercise intensity for subjects with obesity or diabetes when exposed to air pollution and establishing the fine threshold between anti-inflammatory and pro-inflammatory exercise effects.