Update on the Mechanisms of Pulmonary Inflammation and Oxidative Imbalance Induced by Exercise

Systemic and Pulmonary Inflammation/Oxidative Damage: Implications of General and Respiratory Muscle Training in Chronic Spinal-Cord-Injured Patients

Chronic spinal cord injury affects several respiratory-function-related parameters, such as a decrease in respiratory volumes associated with weakness and a tendency to fibrosis of the perithoracic muscles, a predominance of vagal over sympathetic action inducing airway obstructions, and a difficulty in mobilizing secretions. Altogether, these changes result in both restrictive and obstructive patterns. Moreover, low pulmonary ventilation and reduced cardiovascular system functionality (low venous return and right stroke volume) will hinder adequate alveolar recruitment and low O₂ diffusion, leading to a drop in peak physical performance. In addition to the functional effects described above, systemic and localized effects on this organ chronically increase oxidative damage and tissue inflammation. This narrative review describes both the deleterious effects of chronic spinal cord injury on the functional effects of the respiratory system as well as the role of oxidative damage/inflammation in this clinical context. In addition, the evidence for the effect of general and respiratory muscular training on the skeletal muscle as a possible preventive and treatment strategy for both functional effects and underlying tissue mechanisms is summarized.

Oxidative Stress and Antioxidants in Chronic Rhinosinusitis with Nasal Polyps

Oxidative stress results from an imbalance between the production of reactive oxygen species and the body's antioxidant defense system. It plays an important role in the regulation of the immune response and can be a pathogenic factor in various diseases. Chronic rhinosinusitis (CRS) is a complex and heterogeneous disease with various phenotypes and endotypes. Recently, an increasing number of studies have proposed that oxidative stress (caused by both environmental and intrinsic stimuli) plays an important role in the pathogenesis and persistence of CRS. This has attracted the attention of several researchers. The relationship between the presence of reactive oxygen species composed of free radicals and nasal polyp pathology is a key topic receiving attention. This article reviews the role of oxidative stress in respiratory diseases, particularly CRS, and introduces potential therapeutic antioxidants that may offer targeted treatment for CRS.

Physical activity reduces intradermal bacterial load in a murine model submitted to forced swim training - a pilot study

Regular exercise is beneficial to health. This study evaluated the effects of moderate and intense physical exercise modalities on intradermal infection by Staphylococcus aureus in a murine model. Mice that practiced moderate exercise had lower bacterial load on lymph nodes and less inflammatory infiltrate in dermis. They presented greater weight, however, less amount of epididymal fat: the weight was increased while they had fat diminished. A positive correlation was observed between lipid content and bacterial load in mice trained at moderate intensity. Animals that were under high intensity exercises presented superior bacterial load on the lymph nodes, increased neutrophil count and circulating lymphocytes, and had leukocyte recruitment to the dermis augmented, when compared to the ones in moderate exercise. These findings suggest that moderate physical activity modulates the immune response in dermal infection caused by S. aureus in a murine model.

Inflammation and Oxidative Stress as Common Mechanisms of Pulmonary, Autonomic and Musculoskeletal Dysfunction after Spinal Cord Injury

Simple Summary

When a spinal cord injury occurs, the neurons that regulate our voluntary movements, those involved in environment and somatic perception and those that regulate vegetative functions are affected. Once neuronal damage is established, the cells of other tissues are also affected in their functions, altering the interaction between organs and altering the proper functioning of the organism. Multiple studies in animal models, as well as in humans, have recognized as factors involved in organ damage the imbalance between the formation of highly reactive molecules called pro-oxidants and defensive mechanisms called antioxidants. Closely associated with this phenomenon, the inflammatory response is also pathologically activated. In this narrative review, we have analyzed the information involving these pathological processes at the level of the lung, the autonomic nervous system and the skeletal musculature after spinal cord injury. Knowing the abnormal functioning mechanisms that occur after a spinal cord injury not only offers a better understanding of the organic events but also offers future possibilities for therapeutic interventions that may benefit the thousands of patients suffering this pathology.

Abstract

One of the etiopathogenic factors frequently associated with generalized organ damage after spinal cord injury corresponds to the imbalance of the redox state and inflammation, particularly of the respiratory, autonomic and musculoskeletal systems. Our goal in this review was to gain a better understanding of this phenomenon by reviewing both animal and human studies. At the respiratory level, the presence of tissue damage is notable in situations that require increased ventilation due to lower thoracic distensibility and alveolar inflammation caused by higher levels of leptin as a result of increased fatty tissue. Increased airway reactivity, due to loss of sympathetic innervation, and levels of nitric oxide in exhaled air that are similar to those seen in asthmatic patients have also been reported. In addition, the loss of autonomic control efficiency leads to an uncontrolled release of catecholamines and glucocorticoids that induce immunosuppression, as well as a predisposition to autoimmune reactions. Simultaneously, blood pressure regulation is altered with vascular damage and atherogenesis associated with oxidative damage. At the muscular level, chronically elevated levels of prooxidants and lipoperoxidation associated with myofibrillar atrophy are described, with no reduction or reversibility of this process through antioxidant supplementation.

Abscisic acid inhibited reactive oxygen species-mediated endoplasmic reticulum stress by regulating the PPAR-γ signaling pathway in ARDS mice

Acute respiratory distress syndrome (ARDS) is a life-threatening form of a respiratory disorder, and there are few effective therapies. Abscisic acid (ABA) has been proven to be effective in influenza and asthma. Herein, we explored the protective effect of ABA on the resolution of ARDS and the underlying mechanism. Mice were challenged with lipopolysaccharide (LPS) to establish an ARDS model. We found that ABA reduced pulmonary injury, with concomitant suppression of endoplasmic reticulum (ER) stress and reduction of reactive oxygen species (ROS) production. Furthermore, after the elimination of ROS by the specific inhibitor N-acetyl-L-cysteine (NAC), ABA did not further inhibit airway inflammation or ER stress in ARDS mice. In addition, ABA inhibited ROS production through nuclear factor erythroid 2-related factor 2 (Nrf2) activation in parallel with elevated levels of peroxisome proliferator activated receptor γ (PPAR-γ). Furthermore, the addition of a PPAR-γ antagonist abrogated the suppressive action of ABA on inflammation as well as on ER stress and oxidative stress, while NAC restored the protective effect of ABA in ARDS mice treated with a PPAR-γ antagonist. Collectively, ABA protects against LPS-induced lung injury through PPAR-γ signaling, and this effect may be associated with its inhibitory effect on ROS-mediated ER stress.

Effect of Silymarin Supplementation in Lung and Liver Histological Modifications during Exercise Training in a Rodent Model

BACKGROUND

Exercise training induces adaptive physiological and morphological modifications in the entire organism; however, excessive loads of training may increase damage in tissues. The purpose of this study was to evaluate the effect of silymarin in lung and liver histological changes in rats subjected to exercise training (ET).

METHODS

Male Wistar rats were subjected to an 8-week ET treadmill program 5 days per week, 60 min/session, and were previously administered 100 mg ascorbic acid or 100 mg of silymarin.

RESULTS

Silymarin increased alveolar and bronchial muscle size, improve vascularization, and reduced tissue inflammation. In liver, silymarin promoted the reduction of lipid content.

CONCLUSION

Silymarin supplementation may improve inflammation in pulmonary tissue after 8 weeks of the ET treadmill program, improve cell recovery, and reduce intrahepatic lipid content.

The Effect of Physical Activity on Spirometry and Fractional Exhaled Nitric Oxide in Adolescents—Longitudinal Study

Highly intense and chronic physical activity may cause an inflammatory process in the airways. The inflammatory process in the respiratory system can be measured either by the spirometry test and exhaled nitric oxide. The aim of this study was to assess the effect of different levels of physical activity on fractional exhaled nitric oxide (FeNO) and spirometry parameters. Fifty healthy students (volunteers) who were participating in physical activity classes (low level of physical activity) and attending sports training (high and medium level of physical activity) completed two indoor exercise training two to three weeks apart. FeNO was measured twice, at baseline and after 45–60 min of exercise followed by spirometry. There was no significant difference in FeNO values and spirometry parameters between the groups with different physical activity. However, students with the highest level of physical activity presented a higher and significant variance of FeNO levels in comparison to students with lower physical activity. Healthy young adults (professional sportspersons) have a higher internal variability of FeNO. That suggests the initial ongoing inflammatory process in the airways. Any level of physical activity does not affect spirometry parameters before and after training in young healthy adults.

Changes in pulmonary and plasma oxidative stress and inflammation following eccentric and concentric cycling in stable COPD patients

PURPOSE

The purpose of this study was to compare pulmonary and plasma markers of oxidative stress and inflammation after concentric and eccentric cycling bouts in individuals with chronic obstructive pulmonary disease (COPD).

METHODS

Ten patients with moderate COPD level (68.3 ± 9.1 years; forced expiratory volume in 1 s = 68.6 ± 20.4% of predicted) performed 30 min of moderate-intensity concentric (CONC-M: 50% maximum concentric cycling power output; PO_max) and eccentric cycling (ECC-M: 50% PO_max), and high-intensity eccentric cycling (ECC-H: 100% PO_max) in a randomised order. Cardiometabolic demand was monitored during cycling. Indirect markers of muscle damage were assessed before, immediately after, 24 and 48 h after cycling (muscle strength, muscle soreness and creatine kinase activity). Plasma oxidative stress (malondialdehyde: MDA), antioxidant (glutathione peroxidase activity: GPx) and inflammatory markers (IL-6, TNF-α) were measured before and 5 min after cycling. Exhaled breath condensate (EBC) samples were collected before and 15 min after cycling and analysed for hydrogen peroxide (H₂O₂), nitrites (NO^2-) and pH.

RESULTS

Cardiometabolic demand was 40-50% lesser for ECC-M than CONC-M and ECC-H. Greater muscle damage was induced after ECC-H than ECC-M and CONC-M. MDA decreased immediately after CONC-M (- 28%), ECC-M (- 14%), and ECC-H (- 17%), while GPx remained unchanged. IL-6 increased only after ECC-H (28%), while TNF-α remained unchanged after exercise. Pulmonary H₂O₂, NO^2- and pH remained unchanged after exercise.

CONCLUSION

These results suggest that only moderate muscle damage and inflammation were induced after high-intensity eccentric cycling, which did not induce pulmonary or plasmatic increases in markers of oxidative stress.

TRIAL REGISTRATION NUMBER

Trial registration number: DRKS00009755.

Acute FeNO and Blood Pressure Responses to Air Pollution Exposure in Young Adults during Physical Activity

During physical exercise, the absorbed dose of air pollutants increases. Acute effects of exposure to air pollutants during exercise in healthy young adults remain poorly documented. The aim of this study was to assess the acute responses in fractionated exhaled nitric oxide (FeNO) and blood pressure to air pollution exposure during exercise in young adults with different physical activity levels (low or high). In this study, 76 healthy university students participating in physical activity classes (low level of physical activity) and attending sports training (high level of physical activity) completed two indoor exercise trials when air pollutant concentrations were high (exposure trial) and when the quality of the air was good (control trial). We monitored indoor particulate matter with diameter <10 µm and <2.5 µm (PM₁₀ and PM_2.5) and outdoor PM₁₀, nitric oxides (NO₂, NO_x, NO), and sulfur dioxide (SO₂) concentrations. Systolic and diastolic blood pressure (SBP and DBP), heart rate (HR), oxygen saturation (SpO₂)_, and FeNO were measured at baseline and after 45-60 min of physical activity. There were no significant differences between physiological responses to training performed under different exposure conditions in blood pressure, HR, and SpO₂. Significant positive correlations between post-exercise ΔFeNO during exposure trials and ambient air pollutants were found. FeNO increase during the exposure trial was associated with a higher physical activity level and higher outdoor PM₁₀ and NO₂ concentrations. In young and healthy adults, some differences in physiological responses to physical activity between polluted and control environments could be observed. Participants with a high physical activity level were more likely to have an increase in FeNO after exercise in a polluted environment but not after the control exercise trials.

Humidity prevents the exercise-induced formation of hydrogen peroxide and nitrite in exhaled breath condensate in recreational cyclists

PURPOSE

The aerobic exercise affects the respiratory redox-state. The influence of different relative humidity (RH) levels on the formation of respiratory reactive chemical species associated with redox-state altered by exercise has been poorly explored. Our aim was to evaluate the effect of two different RH conditions (40% vs. 90%) on the concentration of hydrogen peroxide and nitrite in exhaled breath condensate ([H₂O₂]_EBC and [NO₂^-]_EBC) and spirometry parameters in recreational cyclists.

METHODS

Sixteen men and women (12/4) (mean age ± SD: 23.5 ± 2.2 years) completed 60-min of cycling at 166.3 ± 26.9 watts (70% of maximum load of [Formula: see text]-max. test, 49.3 ± 7.6 mL·min^-1·kg^-1) at random 40%-RH and 90%-RH conditions separated by 7 days. The two-way RM-ANOVA test was applied to compare [H₂O₂]_EBC, [NO₂^-]_EBC, [NO₂^-]_EBC/[NO₂^-]_Plasma at rest and 80-min post-exercise (80-post); and spirometry parameters at rest, 20-post and 80-post.

RESULTS

The interaction of factors (humidity × time) was significant in [H₂O₂]_EBC, [NO₂^-]_EBC, [NO₂^-]_EBC/[NO₂^-]_Plasma (p = 0.005, p = 0.030, p = 0.043, respectively). At 40%-RH conditions, the same parameters were higher in 80-post than at rest (p < 0.001, p = 0.001, p = 0.014, respectively). At the same time, the [H₂O₂]_EBC and [NO₂^-]_EBC/[NO₂^-]_Plasma were higher in 40%-RH than 90%-RH (p = 0.010, p < 0.001, respectively). The interaction was significant in FEV₁ (p = 0.013) and FEF_25-75% (p = 0.023), but not in FEV₁/FVC (p = 0.362). At 80-post, the changes are kept in 90%-RH (p < 0.001), diminishing in 40%-RH being similar to rest.

CONCLUSION

In recreational cyclists, 90%-RH prevents the increase of hydrogen peroxide and nitrite in exhaled breath condensate samples observed at 40%-RH and prolonging the bronchodilation until 80-post cycling exercise.

Pulmonary and Respiratory Muscle Function in Response to Marathon and Ultra-Marathon Running: A Review

The physiological demands of marathon and ultra-marathon running are substantial, affecting multiple body systems. There have been several reviews on the physiological contraindications of participation; nevertheless, the respiratory implications have received relatively little attention. This paper provides an up-to-date review of the literature pertaining to acute pulmonary and respiratory muscle responses to marathon and ultra-marathon running. Pulmonary function was most commonly assessed using spirometry, with infrequent use of techniques including single-breath rebreathe and whole-body plethysmography. All studies observed statistically significant post-race reductions in one-or-more metrics of pulmonary function, with or without evidence of airway obstruction. Nevertheless, an independent analysis revealed that post-race values rarely fell below the lower-limit of normal and are unlikely, therefore, to be clinically significant. This highlights the virtue of healthy baseline parameters prior to competition and, although speculative, there may be more potent clinical manifestations in individuals with below-average baseline function, or those with pre-existing respiratory disorders (e.g., asthma). Respiratory muscle fatigue was most commonly assessed indirectly using maximal static mouth-pressure manoeuvres, and respiratory muscle endurance via maximum voluntary ventilation (MVV₁₂). Objective nerve-stimulation data from one study, and others documenting the time-course of recovery, implicate peripheral neuromuscular factors as the mechanism underpinning such fatigue. Evidence of respiratory muscle fatigue was more prevalent following marathon compared to ultra-marathon, and might be a factor of work rate, and thus exercise ventilation, which is tempered during longer races. Potential implications of respiratory muscle fatigue on health and marathon/ultra-marathon performance have been discussed, and include a diminished postural stability that may increase the risk of injury when running on challenging terrain, and possible respiratory muscle fatigue-induced effects on locomotor limb blood flow. This review provides novel insights that might influence marathon/ultra-marathon preparation strategies, as well as inform medical best-practice of personnel supporting such events.

Impairment on Cardiopulmonary Function after Marathon: Role of Exhaled Nitric Oxide

Background

The endurance exercise is capable of inducing skeletal muscle, heart, and respiratory fatigue, evidenced by morphofunctional cardiac changes, release of myocardial injury biomarkers, and reduction of maximal voluntary ventilation and oxygen consumption (VO₂) at peak exercise.

Purpose

The aim of this study was to investigate whether marathoners present cardiac fatigue after marathon and whether it correlates with pulmonary levels of exhaled nitric oxide (eNO) and pulmonary inflammation.

Methods

31 male marathoners, age 39 ± 9 years, were evaluated by cardiopulmonary exercise test three weeks before and between three and 15 days after a marathon; eNO analysis and spirometry were evaluated before, immediately after, and 24 and 72 hours after the marathon, and sputum cellularity and cytokine level were assessed before and after the marathon.

Results

Marathon induced an increase in the percentage of macrophages, neutrophils (from 0.65% to 4.28% and 6.79% to 14.11%, respectively), and epithelial cells and a decrease in cytokines in induced sputum, followed by an increase in eNO concentration (20 ± 11 to 35 ± 19 ppb), which presented a significant reduction 24 and 72 hours after marathon (9 ± 12 e 12 ± 9 ppb, p < 0.05). We observed a decrease in the spirometry parameters in all time points assessed after the marathon (p < 0.05) as well as in cardiopulmonary capacity, evidenced by a reduction in VO₂ and ventilation peaks (57 ± 6 to 55 ± 6 mL·min^-1·Kg^-1 and 134 ± 19 to 132 ± 18 Lpm, respectively, p < 0.05). Finally, we observed a negative correlation between the decrease in forced expiratory volume and decrease in eNO 24 and 72 hours after marathon (r = -0.4, p = 0.05).

Conclusion

Reduction in eNO bioavailability after marathon prevents the reduction in cardiopulmonary capacity induced by acute inflammatory pattern after marathon.

The Potential Role of 8-Oxoguanine DNA Glycosylase-Driven DNA Base Excision Repair in Exercise-Induced Asthma

Asthma is characterized by reversible airway narrowing, shortness of breath, wheezing, coughing, and other symptoms driven by chronic inflammatory processes, commonly triggered by allergens. In 90% of asthmatics, most of these symptoms can also be triggered by intense physical activities and severely exacerbated by environmental factors. This condition is known as exercise-induced asthma (EIA). Current theories explaining EIA pathogenesis involve osmotic and/or thermal alterations in the airways caused by changes in respiratory airflow during exercise. These changes, along with existing airway inflammatory conditions, are associated with increased cellular levels of reactive oxygen species (ROS) affecting important biomolecules including DNA, although the underlying molecular mechanisms have not been completely elucidated. One of the most abundant oxidative DNA lesions is 8-oxoguanine (8-oxoG), which is repaired by 8-oxoguanine DNA glycosylase 1 (OGG1) during the base excision repair (BER) pathway. Whole-genome expression analyses suggest a cellular response to OGG1-BER, involving genes that may have a role in the pathophysiology of EIA leading to mast cell degranulation, airway hyperresponsiveness, and bronchoconstriction. Accordingly, this review discusses a potential new hypothesis in which OGG1-BER-induced gene expression is associated with EIA symptoms.