Endurance Training Damages Small Airway Epithelium in Mice

Equine Asthma Diagnostics: Review of Influencing Factors and Difficulties in Diagnosing Subclinical Disease

This literature review focuses on diagnostics of equine asthma (EA), possible influencing factors on diagnostic techniques and latest developments in diagnosing horses during EA remission or with subclinical disease. Routine EA diagnostics include a clinical examination of the respiratory system with percussion and auscultation including a rebreathing examination, and clinical pathology including white blood cells and arterial blood gas analysis. Subsequent diagnostics include bronchoscopy to evaluate the amount and viscosity of respiratory secretion, bronchoalveolar lavage, and the cytology of tracheal aspirates (TAs) and bronchoalveolar lavage fluid (BALF). The grading of EA severity is built on respiratory effort at rest, which is increased in severe equine asthma. The inflammatory subtype is based on BALF cytology, while TA cytology helps to rule out previous bacterial infections. Different factors have an impact on the airways regarding the structure of the epithelium, cytology, and inflammatory markers possibly influencing the diagnosis of EA. Short-term exercise increases the total cell count and inflammatory mediators identified in the BALF of human patients, asymptomatic horses, and other species. Other factors involve cold or chlorinated air, long-term training effects, and concurrent additional respiratory disease, in particular exercise-induced pulmonary hemorrhage. As BALF cytology may be unremarkable during EA remission and low-grade disease, exercise tests and other factors stressing the bronchial epithelium may help to diagnose these patients.

Exercise duration modulates upper and lower respiratory fluid cellularity, antiviral activity, and lung gene expression

Exercise has substantial health benefits, but the effects of exercise on immune status and susceptibility to respiratory infections are less clear. Furthermore, there is limited research examining the effects of prolonged exercise on local respiratory immunity and antiviral activity. To assess the upper respiratory tract in response to exercise, we collected nasal lavage fluid (NALF) from human subjects (1) at rest, (2) after 45 min of moderate-intensity exercise, and (3) after 180 min of moderate-intensity exercise. To assess immune responses of the lower respiratory tract, we utilized a murine model to examine the effect of exercise duration on bronchoalveolar lavage (BAL) fluid immune cell content and lung gene expression. NALF cell counts did not change after 45 min of exercise, whereas 180 min significantly increased total cells and leukocytes in NALF. Importantly, fold change in NALF leukocytes correlated with the post-exercise fatigue rating in the 180-min exercise condition. The acellular portion of NALF contained strong antiviral activity against Influenza A in both resting and exercise paradigms. In mice undergoing moderate-intensity exercise, BAL total cells and neutrophils decreased in response to 45 or 90 min of exercise. In lung lobes, increased expression of heat shock proteins suggested that cellular stress occurred in response to exercise. However, a broad upregulation of inflammatory genes was not observed, even at 180 min of exercise. This work demonstrates that exercise duration differentially alters the cellularity of respiratory tract fluids, antiviral activity, and gene expression. These changes in local mucosal immunity may influence resistance to respiratory viruses, including influenza or possibly other pathogens in which nasal mucosa plays a protective role, such as rhinovirus or SARS-CoV-2.

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.

Management of Exercise-Induced Bronchoconstriction in Athletes

Exercise-induced bronchoconstriction (EIB) is a phenomenon observed in asthma but is also seen in healthy individuals and frequently in athletes. High prevalence rates are observed in athletes engaged in endurance sports, winter sports, and swimming. The pathophysiology of EIB is thought to be related to hyperventilation, cold air, and epithelial damage caused by chlorine and fine particles in inspired air. Several diagnostic procedures can be used; however, the diagnosis of EIB based on self-reported symptoms is not reliable and requires an objective examination. The hyperosmolar inhalation test and eucapnic voluntary hyperpnea test, which involve indirect stimulation of the airway, are useful for the diagnosis of EIB. A short-acting β-agonist is the first choice for prevention of EIB, and an inhaled corticosteroid is essential for patients with asthma. Furthermore, treatment should accommodate antidoping requirements in elite athletes. Tailoring of the therapeutic strategy to the individual case and the prognosis after cessation of athletic activity are issues that should be clarified in the future.

Aerobic exercise training decreases cognitive impairment caused by demyelination by regulating ROCK signaling pathway in aging mice

Recent studies have discovered a strong link between physical exercise and the prevention of neuro-degenerative symptoms, especially in elderly subjects, nonetheless, the exact underlying mechanism remains unclear. In this study, we hypothesized that aerobic exercise training may have a protective effect on myelin sheath in aged mice by regulating the ROCK signal pathway, which is considered as a crucial mechanism for decreasing apoptosis and promoting regeneration. Briefly, C57/BL aged mice underwent an exercise training (5 days/week, lasting 6 weeks). Memory and cognitive impairment were examined using Novel object recognition (NOR) test and Morris water maze test (MWM). Demyelination was explored using Luxol fast blue staining and transmission electron microscopy in the corpus callosum (CC), and the expression of ROCK and apoptotic protein were analyzed via western blot. We demonstrated the impairment of memory and cognitive and the decrease of myelin sheath thickness in aged mice. In addition, severe demyelination was observed in aged mice, accompanied with increased expression of RhoA, ROCK, ATF3, and Caspase 3, and reduced expression of MBP, Olig2, and NG2. Aerobic exercise training improved behavioral functions, increased the expression of MBP and myelin sheath thickness, reduced apoptosis and promoted myelination. To sum up, our data indicate that aerobic exercise training protects demyelination from aging-related white matter injury, which is associated with the up-regulation of ROCK signal pathway.

Cysteinyl Leukotriene Synthesis via Phospholipase A2 Group IV Mediates Exercise-induced Bronchoconstriction and Airway Remodeling

It is well known that the prevalence of asthma is higher in athletes, including Olympic athletes, than in the general population. In this study, we analyzed the mechanism of exercise-induced bronchoconstriction by using animal models of athlete asthma. Mice were made to exercise on a treadmill for a total duration of 1 week, 3 weeks, or 5 weeks. We analyzed airway responsiveness, BAL fluid, lung homogenates, and tissue histology for each period. In mice that were treated (i.e., the treatment model), treatments were administered from the fourth to the fifth week. We also collected induced sputum from human athletes with asthma and analyzed the supernatants. Airway responsiveness to methacholine was enhanced with repeated exercise stimulation, although the cell composition in BAL fluid did not change. Exercise induced hypertrophy of airway smooth muscle and subepithelial collagen deposition. Cysteinyl-leukotriene (Cys-LT) levels were significantly increased with exercise duration. Montelukast treatment significantly reduced airway hyperresponsiveness (AHR) and airway remodeling. Expression of PLA₂G4 (phospholipase A₂ group IV) and leukotriene C₄ synthase in the airway epithelium was upregulated in the exercise model, and inhibition of PLA₂ ameliorated AHR and airway remodeling, with associated lower levels of Cys-LTs. The levels of Cys-LTs in sputum from athletes did not differ between those with and without sputum eosinophilia. These data suggest that AHR and airway remodeling were caused by repeated and strenuous exercise. Cys-LTs from the airway epithelium, but not inflammatory cells, may play an important role in this mouse model.

Aerobic Endurance Exercise Ameliorates Renal Vascular Sclerosis in Aged Mice by Regulating PI3K/AKT/mTOR Signaling Pathway

Renal vascular sclerosis caused by aging plays an important role in the occurrence and development of chronic kidney disease. Clinical studies have confirmed that endurance exercise is able to delay the aging of skeletal muscle and brain tissue. However, to date, few studies have assessed whether endurance exercise is able to improve the occurrence of renal vascular sclerosis caused by natural aging and its related mechanisms. In this study, we investigated the protective effect of aerobic endurance exercise on renal vascular sclerosis in aged mice and its effect on the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway. The results suggested that aerobic endurance exercise preserved kidney morphology and renal function. Glomerular basement membrane thickness was evidently increased, podocyte foot processes were effaced in aged mice, and aerobic endurance exercise significantly ameliorated the overall lesion range. The protein expression of vascular endothelial growth factor (VEGF) and JG12 was lower in the senile control group (OC group). The protein expression of VEGF and JG12 was significantly increased after aerobic endurance exercise. Furthermore, aerobic endurance exercise resulted in downregulation of Bax, Caspase 3, IL-6, and senescent cells and upregulation of Bcl-2. The upregulation of PI3K and its downstream signal molecules AKT and mTOR after aerobic endurance exercise was further observed. Our observations indicated that aerobic endurance exercise may inhibit renal vascular sclerosis in aged mice by regulating the PI3K/AKT/mTOR signaling pathway.

Long-term endurance running activity causes pulmonary changes depending on the receptor for advanced glycation end-products

The receptor for advanced glycation end-products (RAGE) is an immunoglobulin superfamily cell adhesion molecule predominantly expressed in the lung, but its pulmonary importance is incompletely understood. Since RAGE alters the respiratory mechanics, which is also challenged by endurance running activity, we studied the RAGE-dependent effect of higher running activity on selected lung parameters in a long-term animal model using wild-type (WT) and RAGE knockout (RAGE-KO) mice. Higher long-term running activity of mice was ensured by providing a running wheel for 8 months. Recording the running activity revealed that RAGE-KO mice are more active than WT mice. RAGE-KO caused an increased lung compliance which additionally increased after long-term running activity with minor limitation of the expiratory flow, whereas the respiratory mechanics of WT mice remained constant. Although RAGE-KO mice had a less dense alveolar-capillary barrier for immune cells, higher long-term running activity led only in WT mice to more leukocyte infiltrations in the lung tissue and aggregations of lymphoid cells in the airways. In this regard, WT mice of the activity group were also more sensitive to ventilation-mediated airway damages. In contrast to RAGE-KO mice of the activity group, lungs of WT mice did not show an increase in the cAMP response element-binding protein, a transcription factor regulating many pro-survival genes. Our findings suggest an important role of RAGE in the physical capability due to its effect on the lung compliance as well as RAGE as a mediator of airway damages caused by higher long-term running activity.

Mechanisms of exercise-induced bronchoconstriction in athletes: Current perspectives and future challenges

The evidence of exercise-induced bronchoconstriction (EIB) without asthma (EIBw_A ) occurring in athletes led to speculate about different endotypes inducing respiratory symptoms within athletes. Classical postulated mechanisms for bronchial obstruction in this population include the osmotic and the thermal hypotheses. More recently, the presence of epithelial injury and inflammation in the airways of athletes was demonstrated. In addition, neuronal activation has been suggested as a potential modulator of bronchoconstriction. Investigation of these emerging mechanisms is of major importance as EIB is a significant problem for both recreational and competitive athletes and is the most common chronic condition among Olympic athletes, with obvious implications for their competing performance, health and quality of life. Hereby, we summarize the latest achievements in this area and identify the current gaps of knowledge so that future research heads toward better defining the etiologic factors and mechanisms involved in development of EIB in elite athletes as well as essential aspects to ultimately propose preventive and therapeutic measures.

Effects of Conjugated Linoleic Acid Associated With Endurance Exercise on Muscle Fibres and Peroxisome Proliferator-Activated Receptor γ Coactivator 1 α Isoforms

Conjugated linoleic acid (CLA) has been reported to improve muscle hypertrophy, steroidogenesis, physical activity, and endurance capacity in mice, although the molecular mechanisms of its actions are not completely understood. The aim of the present study was to identify whether CLA alters the expression of any of the peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) isoforms, and to evaluate the possible existence of fibre-type-specific hypertrophy in the gastrocnemius and plantaris muscles. Mice were randomly assigned to one of four groups: placebo sedentary, CLA sedentary, placebo trained, or CLA trained. The CLA groups were gavaged with 35 μl per day of Tonalin® FFA 80 food supplement containing CLA throughout the 6-week experimental period, whereas the placebo groups were gavaged with 35 μl sunflower oil each day. Each administered dose of CLA corresponded to approximately 0.7 g/kg or 0.5%, of the dietary daily intake. Trained groups ran 5 days per week on a Rota-Rod for 6 weeks at increasing speeds and durations. Mice were sacrificed by cervical dislocation and hind limb posterior muscle groups were dissected and used for histological and molecular analyses. Endurance training stimulated mitochondrial biogenesis by PGC1α isoforms (tot, α1, α2, and α3) but CLA supplementation did not stimulate PGC1α isoforms or mitochondrial biogenesis in trained or sedentary mice. In the plantaris muscle, CLA supplementation induced a fibre-type-specific hypertrophy of type IIx muscle fibres, which was associated with increased capillary density and was different from the fibre-type-specific hypertrophy induced by endurance exercise (of types I and IIb muscle fibres). J. Cell. Physiol. 232: 1086-1094, 2017. © 2016 Wiley Periodicals, Inc.

Analysis of Cell Turnover in the Bronchiolar Epithelium Through the Normal Aging Process

PURPOSE

Aging is associated with changes in the lung that leads to a decrease in its function. Alterations in structure and function in the small airways are well recognized in chronic lung diseases. The aim of this study was the assessment of cell turnover in the bronchiolar epithelium of mouse through the normal aging process.

METHODS

Lungs from CD1 mice at the age of 2, 6, 12, 18, or 24 months were fixed in neutral-buffered formalin and paraffin-embedded. Proliferating cell nuclear antigen was examined by immunohistochemistry. Apoptosis was analyzed by in situ end-labeling of fragmented DNA. Epithelial dimensions were analyzed by morphometry.

RESULTS

The 2-month-old mice showed significantly higher number of proliferating cells when compared with mice at all other age groups. The number of apoptotic cells in mice at 24 months of age was significantly greater than in mice at all other age groups. Thus, the number of epithelial cells decreased as the age of the subject increased. We also found reductions in both area and height of the bronchiolar epithelium in mice at 18 and 24 months of age.

CONCLUSIONS

We found a decrease in the total number of epithelial cells in the aged mice, which was accompanied by a thinning of the epithelium. These changes reflect a dysregulated tissue regeneration process in the bronchiolar epithelium that might predispose to respiratory diseases in elderly subjects.

Air quality and temperature effects on exercise-induced bronchoconstriction

Exercise-induced bronchoconstriction (EIB) is exaggerated constriction of the airways usually soon after cessation of exercise. This is most often a response to airway dehydration in the presence of airway inflammation in a person with a responsive bronchial smooth muscle. Severity is related to water content of inspired air and level of ventilation achieved and sustained. Repetitive hyperpnea of dry air during training is associated with airway inflammatory changes and remodeling. A response during exercise that is related to pollution or allergen is considered EIB. Ozone and particulate matter are the most widespread pollutants of concern for the exercising population; chronic exposure can lead to new-onset asthma and EIB. Freshly generated emissions particulate matter less than 100 nm is most harmful. Evidence for acute and long-term effects from exercise while inhaling high levels of ozone and/or particulate matter exists. Much evidence supports a relationship between development of airway disorders and exercise in the chlorinated pool. Swimmers typically do not respond in the pool; however, a large percentage responds to a dry air exercise challenge. Studies support oxidative stress mediated pathology for pollutants and a more severe acute response occurs in the asthmatic. Winter sport athletes and swimmers have a higher prevalence of EIB, asthma and airway remodeling than other athletes and the general population. Because of fossil fuel powered ice resurfacers in ice rinks, ice rink athletes have shown high rates of EIB and asthma. For the athlete training in the urban environment, training during low traffic hours and in low traffic areas is suggested.

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

The mechanisms involved in the generation of oxidative damage and lung inflammation induced by physical exercise are described. Changes in lung function induced by exercise involve cooling of the airways, fluid evaporation of the epithelial surface, increased contact with polluting substances, and activation of the local and systemic inflammatory response. The present work includes evidence obtained from the different types of exercise in terms of duration and intensity, the effect of both acute performance and chronic performance, and the influence of special conditions such as cold weather, high altitude, and polluted environments. Levels of prooxidants, antioxidants, oxidative damage to biomolecules, and cellularity, as well as levels of soluble mediators of the inflammatory response and its effects on tissues, are described in samples of lung origin. These samples include tissue homogenates, induced sputum, bronchoalveolar lavage fluid, biopsies, and exhaled breath condensate obtained in experimental protocols conducted on animal and human models. Finally, the need to simultaneously explore the oxidative/inflammatory parameters to establish the interrelation between them is highlighted.

Exercise and asthma: an overview

The terms 'exercise-induced asthma' (EIA) and 'exercise-induced bronchoconstriction' (EIB) are often used interchangeably to describe symptoms of asthma such as cough, wheeze, or dyspnoea provoked by vigorous physical activity. In this review, we refer to EIB as the bronchoconstrictive response and to EIA when bronchoconstriction is associated with asthma symptoms. EIB is a common occurrence for most of the asthmatic patients, but it also affects more than 10% of otherwise healthy individuals as shown by epidemiological studies. EIA and EIB have a high prevalence also in elite athletes, especially within endurance type of sports, and an athlete's asthma phenotype has been described. However, the occurrence in elite athletes shows that EIA/EIB, if correctly managed, may not impair physical activity and top sports performance. The pathogenic mechanisms of EIA/EIB classically involve both osmolar and vascular changes in the airways in addition to cooling of the airways with parasympathetic stimulation. Airways inflammation plays a fundamental role in EIA/EIB. Diagnosis and pharmacological management must be carefully performed, with particular consideration of current anti-doping regulations, when caring for athletes. Based on the demonstration that the inhaled asthma drugs do not improve performance in healthy athletes, the doping regulations are presently much less strict than previously. Some sports are at a higher asthma risk than others, probably due to a high environmental exposure while performing the sport, with swimming and chlorine exposure during swimming as one example. It is considered very important for the asthmatic child and adolescent to master EIA/EIB to be able to participate in physical activity on an equal level with their peers, and a precise early diagnosis with optimal treatment follow-up is vital in this aspect. In addition, surprising recent preliminary evidences offer new perspectives for moderate exercise as a potential therapeutic tool for asthmatics.

Exercise and asthma: an overview

The terms 'exercise-induced asthma' (EIA) and 'exercise-induced bronchoconstriction' (EIB) are often used interchangeably to describe symptoms of asthma such as cough, wheeze, or dyspnoea provoked by vigorous physical activity. In this review, we refer to EIB as the bronchoconstrictive response and to EIA when bronchoconstriction is associated with asthma symptoms. EIB is a common occurrence for most of the asthmatic patients, but it also affects more than 10% of otherwise healthy individuals as shown by epidemiological studies. EIA and EIB have a high prevalence also in elite athletes, especially within endurance type of sports, and an athlete's asthma phenotype has been described. However, the occurrence in elite athletes shows that EIA/EIB, if correctly managed, may not impair physical activity and top sports performance. The pathogenic mechanisms of EIA/EIB classically involve both osmolar and vascular changes in the airways in addition to cooling of the airways with parasympathetic stimulation. Airways inflammation plays a fundamental role in EIA/EIB. Diagnosis and pharmacological management must be carefully performed, with particular consideration of current anti-doping regulations, when caring for athletes. Based on the demonstration that the inhaled asthma drugs do not improve performance in healthy athletes, the doping regulations are presently much less strict than previously. Some sports are at a higher asthma risk than others, probably due to a high environmental exposure while performing the sport, with swimming and chlorine exposure during swimming as one example. It is considered very important for the asthmatic child and adolescent to master EIA/EIB to be able to participate in physical activity on an equal level with their peers, and a precise early diagnosis with optimal treatment follow-up is vital in this aspect. In addition, surprising recent preliminary evidences offer new perspectives for moderate exercise as a potential therapeutic tool for asthmatics.

Airway inflammation, cough and athlete quality of life in elite female cross-country skiers: A longitudinal study

The aim of this study was to investigate the effect of a season of cross-country training and racing on airway inflammation, cough symptoms, and athlete quality of life in female skiers. Eighteen elite female skiers performed sputum induction and completed the Leicester Cough Questionnaire (LCQ) and the Recovery-Stress Questionnaire (REST-Q) at three time points (T1 - May/Jun, T2 - Oct/Nov, T3 - Jan-Mar) during the year. No changes were observed between T1 and T2. However, an increase in sputum eosinophils and lymphocytes (P < 0.05) and a significant change in all three domains of the LCQ were observed between T1 and T3 (P < 0.05). A significant association was found between the total yearly hours of training and the change in the total cell count (r(2)  = 0.74; P = 0.006), and a number of other sputum cell counts between T1 and T3. No changes were observed for any domain of the REST-Q. The results of this study demonstrate that airway inflammation and cough symptoms are significantly increased in elite female cross-country skiers across a year of training and racing. The increase in airway inflammation is related to the total amount of training and is worse during the winter months when athletes are training and racing in cold, dry air.

Biological monitoring of particulate matter accumulated in the lungs of urban asthmatic children in the Tel-Aviv area

PURPOSE

Lung inflammation from exposure to airborne particulate matter (PM) may be responsible for morbidity in asthma, but several studies using environmental monitoring data showed inconsistent results. Thus, the aim of this study was to evaluate the capability of induced sputum (IS) technology in order to biologically monitor PM in the lungs of urban asthmatic children.

METHODS

We collected clinical, demographic, biological and environmental monitoring data on 136 children referred for asthma evaluations. The study participants were divided into two groups according to IS eosinophil counts of <3% (non-eosinophilic inflammation, n = 52) and ≥3% (eosinophilic inflammation, n = 84).

RESULTS

The eosinophilic group displays significantly higher levels of fractional exhaled nitric oxide than the non-eosinophilic one (58.8 ± 47.5 vs 28.9 ± 34.2 ppm, p = 0.007). Particles (0-2.5 and 0-5 µm) comprised a strong risk factor for eosinophilic inflammation in IS (≥3%). Children with >80% of particles (0-2.5 µm) out of the total PM accumulated in the airways displayed the highest OR 10.7 (CI 2.052-56.4 p = 0.005) for an existing eosinophilic inflammation. Heme oxygenase-1 (HO-1) enzyme levels in IS positively correlated with % eosinophils and with particles in IS ranging between 2 and 3 μm. The level of HO-1 enzyme activity and FEV1/FVC in children with <3% eosinophils, but not ≥3%, was positively and significantly correlated, showing a protective effect of HO-1.

CONCLUSION

Accumulation of PM involves oxidative stress pathways and is a risk factor for developing eosinophilic inflammation in asthmatic children. IS can biologically monitor this process.

The role of small airway disease in asthma

PURPOSE OF REVIEW

This review provides an update on the importance of the peripheral 'small' airways in asthma. As the small airways account for less than 10% of total airway resistance, thus having little impact on standard lung function measures such as forced expiratory volume and peak flow, they have been referred to as the 'silent zone'.

RECENT FINDINGS

The study has revealed that small airway involvement is present in all stages of asthmatic disease, being related to important clinical phenotypes such as nocturnal asthma, exercise-induced asthma, and difficult-to-control asthma, including those with the risk of repeated asthma exacerbations. Uncontrolled small airway inflammation is related to airway remodeling and progression of the disease, with a more rapid decline in the lung function. Moreover, studies on both children and adults have shown that the involvement of the small airways represents a crucial step in asthma development. New tools have been developed and old tools have been refined, providing an opportunity to better understand small airway inflammation and dysfunction.

SUMMARY

Small airway inflammation is present in all stages of asthmatic disease and plays an important role in many key clinical conditions/phenotypes. In order to control the disease, we need to target small airway inflammation, which is not only difficult to reach by standard inhaled medications but also to some extent different. A better understanding of the important role small airways are playing in asthma will show that the 'silent zone' is by far not silent at all.

Aligning mouse models of asthma to human endotypes of disease

Substantial gains in understanding the pathophysiologic mechanisms underlying asthma have been made using preclinical mouse models. However, because asthma is a complex, heterogeneous syndrome that is rarely due to a single allergen and that often presents in the absence of atopy, few of the promising therapeutics that demonstrated effectiveness in mouse models have translated into new treatments for patients. This has resulted in an urgent need to characterize T helper (Th) 2-low, non-eosinophilic subsets of asthma, to study models that are resistant to conventional treatments such as corticosteroids and to develop therapies targeting patients with severe disease. Classifying asthma based on underlying pathophysiologic mechanisms, known as endotyping, offers a stratified approach for the development of new therapies for asthma. In preclinical research, new models of asthma are being utilized that more closely resemble the clinical features of different asthma endotypes, including the presence of interleukin-17 and a Th17 response, a biomarker of severe disease. These models utilize more physiologically relevant sensitizing agents, exacerbating factors and allergens, as well as incorporate time points that better reflect the natural history and chronicity of clinical asthma. Importantly, some models better represent non-classical asthma endotypes that facilitate the study of non-Th2-driven pathology and resemble the complex nature of clinical asthma, including corticosteroid resistance. Placing mouse asthma models into the context of human asthma endotypes will afford a more relevant approach to the understanding of pathophysiological mechanisms of disease that will afford the development of new therapies for those asthmatics that remain difficult to treat.

Endurance exercise and conjugated linoleic acid (CLA) supplementation up-regulate CYP17A1 and stimulate testosterone biosynthesis

A new role for fat supplements, in particular conjugated linoleic acid (CLA), has been delineated in steroidogenesis, although the underlying molecular mechanisms have not yet been elucidated. The aims of the present study were to identify the pathway stimulated by CLA supplementation using a cell culture model and to determine whether this same pathway is also stimulated in vivo by CLA supplementation associated with exercise. In vitro, Leydig tumour rat cells (R2C) supplemented with different concentrations of CLA exhibited increasing testosterone biosynthesis accompanied by increasing levels of CYP17A1 mRNA and protein. In vivo, trained mice showed an increase in free plasma testosterone and an up-regulation of CYP17A1 mRNA and protein. The effect of training on CYP17A1 expression and testosterone biosynthesis was significantly higher in the trained mice supplemented with CLA compared to the placebo. The results of the present study demonstrated that CLA stimulates testosterone biosynthesis via CYP17A1, and endurance training led to the synthesis of testosterone in vivo by inducing the overexpression of CYP17A1 mRNA and protein in the Leydig cells of the testis. This effect was enhanced by CLA supplementation. Therefore, CLA-associated physical activity may be used for its steroidogenic property in different fields, such as alimentary industry, human reproductive medicine, sport science, and anti-muscle wasting.

Air quality and exercise-induced bronchoconstriction in elite athletes

A higher prevalence of airway hyperresponsiveness, airway remodeling, and asthma has been identified among athletes who compete and train in environmental conditions of cold dry air and/or high air pollution. Repeated long-duration exposure to cold/dry air at high minute ventilation rates can cause airway damage. Competition or training at venues close to busy roadways, or in indoor ice arenas or chlorinated swimming pools, harbors a risk for acute and chronic airway disorders from high pollutant exposure. This article discusses the effects of these harsh environments on the airways, and summarizes potential mechanisms and prevalence of airway disorders in elite athletes.

Effects of aerobic exercise on chronic allergic airway inflammation and remodeling in guinea pigs

We evaluated the effects of aerobic exercise (AE) on airway inflammation, exhaled nitric oxide levels (ENO), airway remodeling, and the expression of Th1, Th2 and regulatory cytokines in a guinea pig asthma model. Animals were divided into 4 groups: non-trained and non-sensitized (C), non-sensitized and AE (AE), ovalbumin-sensitized and non-trained (OVA), and OVA-sensitized and AE (OVA+AE). OVA inhalation was performed for 8 weeks, and AE was conducted for 6 weeks beginning in the 3rd week of OVA sensitization. Compared to the other groups, the OVA+AE group had a reduced density of eosinophils and lymphocytes, reduced expression of interleukin (IL)-4 and IL-13 and an increase in epithelium thickness (p<0.05). AE did not modify airway remodeling or ENO in the sensitized groups (p>0.05). Neither OVA nor AE resulted in differences in the expression of IL-2, IFN-γ, IL-10 or IL1-ra. Our results show that AE reduces the expression of Th2 cytokines and allergic airway inflammation and induces epithelium remodeling in sensitized guinea pigs.

Chronic aspiration shifts the immune response from adaptive immunity to innate immunity in a murine model of asthma

OBJECTIVE AND DESIGN

The hypothesis that aspiration of gastric fluid drives the anti-ovalbumin response toward a Th2 reaction even in animals not prone to Th2 responses was evaluated.

SUBJECTS

Forty-eight male C57BL/6 mice were used.

METHODS

Mice were sensitized and challenged with ovalbumin starting 5 weeks prior to the initiation of weekly aspirations of either gastric fluid or normal saline as a control. Weekly aspiration continued during the course of exposure to ovalbumin.

TREATMENT

Aspiration consisted of 50 μl of gastric fluid with 50 μl of 0.9 % normal saline used as a control. Antigen exposure consisted of sensitization to ovalbumin via intraperitoneal injection on days 0 and 14 and challenge on day 21 with aerosolized antigen for 30 min.

RESULTS

No evidence of a shift toward a Th2 response as a result of gastric fluid aspiration was seen in the Th1-prone strain utilized, although a profound down-regulation of a broad array of T cell-associated cytokines and chemokines and up-regulation of macrophage-associated markers was observed as a result of aspiration.

CONCLUSIONS

These data provide support for the hypothesis that the clinical association between asthma and gastroesophageal reflux disease (GERD) does not involve an exacerbation of asthma by GERD-associated aspiration of gastric fluid, but may cause immune reactions unrelated to the asthma pathology.

Airway remodeling and inflammation in competitive swimmers training in indoor chlorinated swimming pools

BACKGROUND

Airway disorders are common in regular chlorinated swimming pool attendees, particularly competitive athletes, but the impact of intense swimming training on airway function and structure remains unclear.

OBJECTIVE

This study aimed to evaluate airway inflammation and remodeling in elite swimmers.

METHODS

Twenty-three elite swimmers were tested during off-training season. All had exhaled nitric oxide measurement, methacholine test, eucapnic voluntary hyperpnea challenge, allergy skin prick tests, and bronchoscopy with bronchial biopsies. Clinical data and tissues from 10 age-matched mild-asthmatic and 10 healthy nonallergic subjects were used for comparison.

RESULTS

Swimmers had increased airway mucosa eosinophil and mast cell counts than did controls (P < .05). They had more goblet cell hyperplasia and higher mucin expression than did healthy or asthmatic subjects (P < .05). A greater submucosal type I and III collagen expression and tenascin deposition was also observed in swimmers than in controls (P < .05). Neither exhaled nitric oxide nor airway responsiveness to methacholine or eucapnic voluntary hyperpnea challenge correlated with these inflammatory and remodeling changes.

CONCLUSION

Intense, long-term swimming training in indoor chlorinated swimming pools is associated with airway changes similar to those seen in mild asthma, but with higher mucin expression. These changes were independent from airway hyperresponsiveness. The long-term physiological and clinical consequences of these changes remain to be clarified.

Ultrafine and nanoparticles-induced oxidative stress: the role of heme oxygenase-1 and carbon monoxide as anti-inflammatory pathways

INTRODUCTION

Particulate matter (PM) is an environmental factor that has been associated with increased respiratory morbidity and mortality. The major effect of ambient PM on the pulmonary system is that it promotes inflammation in susceptible people. One of the mechanisms by which ambient PM exerts its proinflammatory effects is by generating increased oxidative stress induced by chemical compounds and metal constituents. Cellular responses to PM-induced oxidative stress include activation of antioxidant defense. OBJECTIVE. To investigate the anti-inflammatory and anti-apoptotic roles of heme oxygenase-1 (HO-1) and carbon monoxide (CO) in the PM-induced oxidative stress arm, inflammation, and toxicity. Methods. Particle size analyses were performed according to a laser technique based on the time of transition theory using an Eyetech Analyzer (Donner Technologies Ltd., Israel). HO-1 was analyzed by quantitative reverse transcriptase polymerase chain reaction (RT-PCR) in induced sputum (IS) samples.

RESULTS

We demonstrate the feasibility of measuring micro- and nanoparticles in IS samples of exposed individuals in and out of the workplace to determine the protective role of HO-1 and CO.

CONCLUSIONS

Ongoing studies will further elucidate the protective role of HO-1 and CO in the PM-induced oxidative stress model.

Apoptosis and the airway epithelium

The airway epithelium functions as a barrier and front line of host defense in the lung. Apoptosis or programmed cell death can be elicited in the epithelium as a response to viral infection, exposure to allergen or to environmental toxins, or to drugs. While apoptosis can be induced via activation of death receptors on the cell surface or by disruption of mitochondrial polarity, epithelial cells compared to inflammatory cells are more resistant to apoptotic stimuli. This paper focuses on the response of airway epithelium to apoptosis in the normal state, apoptosis as a potential regulator of the number and types of epithelial cells in the airway, and the contribution of epithelial cell apoptosis in important airways diseases.

Hyperpnea-induced bronchoconstriction and urinary CC16 levels in athletes

PURPOSE

Exercise-induced bronchoconstriction (EIB) is a common condition in both individuals with asthma and otherwise healthy elite athletes. Although excessive water loss by peripheral airways during hyperpnea is regarded as the initial trigger for EIB, the cascade of events that follows remains unclear. Our goal was to establish whether transient disruption of the airway epithelial barrier occurs after a short period of hyperpnea of dry air in athletes with EIB.

METHODS

Urinary concentration of the pneumoprotein Clara cell (CC16) was used as an assumed biomarker of lung epithelial cell damage or dysfunction. Samples were collected at baseline and for 90 min after an 8-min eucapnic voluntary hyperpnea (EVH) test in 50 female individuals (28 athletes and 22 untrained).

RESULTS

Nineteen subjects (10 athletes) demonstrated a sustained bronchoconstriction after EVH (mean±SE forced expiratory volume in the first second (FEV1) fall from baseline=23.4%±2.6%). The remaining subjects had a negative challenge result with an FEV1 fall of 5.9%±0.6%. An increase (P<0.001) in urinary CC16 concentration was noticed after EVH in all but one subject, with no group difference (median CC16 increase before to after challenge: athletes EVH 0.083 ng·μmol, athletes EVH 0.223 ng·μmol, untrained EVH 0.074 ng·μmol, untrained EVH 0.571 ng·μmol; P>0.05).

CONCLUSIONS

Urinary levels of CC16 are increased after EVH in all individuals (trained and untrained, with and without EIB) suggestive of dehydration-induced perturbation of the distal respiratory epithelium during episodes of hyperventilation.

Effect of inspired air conditions on exercise-induced bronchoconstriction and urinary CC16 levels in athletes

Injury to the airway epithelium has been proposed as a key susceptibility factor for exercise-induced bronchoconstriction (EIB). Our goals were to establish whether airway epithelial cell injury occurs during EIB in athletes and whether inhalation of warm humid air inhibits this injury. Twenty-one young male athletes (10 with a history of EIB) performed two 8-min exercise tests near maximal aerobic capacity in cold dry (4°C, 37% relative humidity) and warm humid (25°C, 94% relative humidity) air on separate days. Postexercise changes in urinary CC16 were used as a biomarker of airway epithelial cell perturbation and injury. Bronchoconstriction occurred in eight athletes in the cold dry environment and was completely blocked by inhalation of warm humid air [maximal fall in forced expiratory volume in 1 s = 18.1 ± 2.1% (SD) in cold dry air and 1.7 ± 0.8% in warm humid air, P < 0.01]. Exercise caused an increase in urinary excretion of CC16 in all subjects ( P < 0.001), but this rise in CC16 was blunted following inhalation of warm humid air [median CC16 increase pre- to postchallenge = 1.91 and 0.35 ng/μmol in cold dry and warm humid air, respectively, in athletes with EIB ( P = 0.017) and 1.68 and 0.48 ng/μmol in cold dry and warm humid air, respectively, in athletes without EIB ( P = 0.002)]. The results indicate that exercise hyperpnea transiently disrupts the airway epithelium of all athletes (not only in those with EIB) and that inhalation of warm moist air limits airway epithelial cell perturbation and injury.

Asthma in elite athletes: pathogenesis, diagnosis, differential diagnoses, and treatment

Elite athletes have a high prevalence of asthma and exercise-induced bronchoconstriction. Although respiratory symptoms can be suggestive of asthma, the diagnosis of asthma in elite athletes cannot be based solely on the presence or absence of symptoms; diagnosis should be based on objective measurements, such as the eucapnic voluntary hyperpnea test or exercise test. When considering that not all respiratory symptoms are due to asthma, other diagnoses should be considered. Certain regulations apply to elite athletes who require asthma medication for asthma. Knowledge of these regulations is essential when treating elite athletes. This article is aimed at physicians who diagnose and treat athletes with respiratory symptoms. It focuses on the pathogenesis of asthma and exercise-induced bronchoconstriction in elite athletes and how the diagnosis can be made. Furthermore, treatment of elite athletes with asthma, anti-doping regulations, and differential diagnoses such as exercise-induced laryngomalacia are discussed.

Airway vascular damage in elite swimmers

We postulated that high level swimming can promote airway inflammation and thus asthma by enhancing local vascular permeability. We aimed to test this hypothesis by a cross-sectional study comparing swimmers (n = 13, 17 ± 3 years, competing 7 ± 4 years, training 18 ± 3 h per week), asthmatic-swimmers (n = 6, 17 ± 2 years, competing 8 ± 3 years, training 16 ± 4 h per week), and asthmatics (n = 19, 14 ± 3 years). Subjects performed induced sputum and had exhaled nitric oxide, lung volumes, and airway responsiveness determined. Airway vascular permeability index was defined as the ratio of albumin in sputum and serum. Results from the multiple linear regression showed each unit change in airway vascular permeability index was associated with an increase of 0.97% (95%CI: 0.02 to 1.92; p = 0.047) in sputum eosinophilis, and of 2.64% (95%CI:0.96 to 4.31; p = 0.006) in sputum neutrophils after adjustment for confounders. In a general linear model no significant differences between airway vascular permeability between index study groups existed, after controlling for sputum eosinophilis and neutrophils. In conclusion, competitive swimmers training in chlorine-rich pools have similar levels of airway vascular permeability than asthmatics. Although competitive swimming has been associated with asthma, airway inflammation and airway hyperesponsiveness do not seem to be dependent on increased airway vascular permeability.

Airway epithelium mediates the anti-inflammatory effects of exercise on asthma

Airway epithelium plays an important role in the asthma physiopathology. Aerobic exercise decreases Th2 response in murine models of allergic asthma, but its effects on the structure and activation of airway epithelium in asthma are unknown. BALB/c mice were divided into control, aerobic exercise, ovalbumin-sensitized and ovalbumin-sensitized plus aerobic exercise groups. Ovalbumin sensitization occurred on days 0, 14, 28, 42, and aerosol challenge from day 21 to day 50. Aerobic exercise started on day 22 and ended on day 50. Total cells and eosinophils were reduced in ovalbumin-sensitized group submitted to aerobic exercise. Aerobic exercise also reduced the oxidative and nitrosative stress and the epithelial expression of Th2 cytokines, chemokines, adhesion molecules, growth factors and NF-kB and P2X7 receptor. Additionally, aerobic exercise increased the epithelial expression of IL-10 in non-sensitized and sensitized animals. These findings contribute to the understanding of the beneficial effects of aerobic exercise for chronic allergic airway inflammation, suggesting an immune-regulatory role of exercise on airway epithelium.

Modeling asthma in mice: what have we learned about the airway epithelium?

Clinical reports of areas of damaged airway epithelium associated with shed epithelial cells in bronchoalveolar lavage fluid, aberrant epithelial repair processes, and altered cytokine and growth factor release have highlighted some fundamental differences between the airway epithelium in individuals with and without asthma. However, the consequences of these epithelial changes are not clearly defined, and may be difficult to assess in the clinic. In this Review, we answer the two questions. (1) What in vivo models and methods have been used to inform us about airway epithelium damage, repair, and immune responses? Our response focuses on genetic influences as well as allergen exposure, environmental/chemical, and mechanical models. (2) How can we improve on existing mouse models to understand changes in airway epithelium biology in asthma? In answering the second question, we include exciting recent studies that have combined multiple exposure methods and/or epithelium-centric outcome measurements. By addressing these two questions, we propose that future interrogation of epithelial responses of both existing and nascent mouse models may provide greater understanding of the mechanisms underlying airway inflammation and remodeling in asthma with hope of generating novel therapeutic targets.

Effects of exercise training on airway responsiveness and airway cells in healthy subjects

Airway responsiveness to methacholine (Mch) in the absence of deep inspirations (DIs) is lower in athletes compared with sedentary individuals. In this prospective study, we tested the hypothesis that a training exercise program reduces the bronchoconstrictive effect of Mch. Ten healthy sedentary subjects (M/F: 3/7; mean + or - SD age: 22 + or - 3 yr) entered a 10-wk indoor rowing exercise program on rowing ergometer and underwent Mch bronchoprovocation in the absence of DIs at baseline, at weeks 5 and 10, as well as 4-6 wk after the training program was completed. Exercise-induced changes on airway cells and markers of airway inflammation were also assessed by sputum induction and venous blood samples. Mean power output during the 1,000 m test was 169 + or - 49 W/stroke at baseline, 174 + or - 49 W/stroke at 5 wk, and 200 + or - 60 W/stroke at 10 wk of training (P < 0.05). The median Mch dose used at baseline was 50 mg/ml (range 25-75 mg/ml) and remained constant per study design. At the pretraining evaluation, the percent reduction in the primary outcome, the inspiratory vital capacity (IVC) after inhalation of Mch in the absence of DIs was 31 +/- 13%; at week 5, the Mch-induced reduction in IVC was 22 + or - 19%, P = 0.01, and it further decreased to 15 + or - 11% at week 10 (P = 0.0008). The percent fall in IVC 4-6 wk after the end of training was 15 + or - 11% (P = 0.87 vs. end of training). Changes in airway cells were not associated with changes in airway responsiveness. Our data show that a course of exercise training can attenuate airway responsiveness against Mch inhaled in the absence of DIs in healthy subjects and suggest that a sedentary lifestyle may favor development of airways hyperresponsiveness.

Bronchial epithelial damage after a half-marathon in nonasthmatic amateur runners

High neutrophil counts in induced sputum have been found in nonasthmatic amateur runners at rest and after a marathon, but the pathogenesis of airway neutrophilia in athletes is still poorly understood. Bronchial epithelial damage may occur during intense exercise, as suggested by investigations conducted in endurance-trained mice and competitive human athletes studied under resting conditions. To gain further information on airway changes acutely induced by exercise, airway cell composition, apoptosis, IL-8 concentration in induced sputum, and serum CC-16 level were measured in 15 male amateur runners at rest (baseline) and shortly after a half-marathon. Different from results obtained after a marathon, neutrophil absolute counts were unchanged, whereas bronchial epithelial cell absolute counts and their apoptosis increased significantly ( P < 0.01). IL-8 in induced sputum supernatants almost doubled postrace compared with baseline ( P < 0.01) and correlated positively with bronchial epithelial cell absolute counts ( R2 = 0.373, P < 0.01). Serum CC-16 significantly increased after all races ( P < 0.01). These data show mild bronchial epithelial cell injury acutely induced by intense endurance exercise in humans, extending to large airways the data obtained in peripheral airways of endurance-trained mice. Therefore, neutrophil influx into the airways of athletes may be secondary to bronchial epithelial damage associated with intense exercise.

Airway hyperresponsiveness to methacholine, adenosine 5-monophosphate, mannitol, eucapnic voluntary hyperpnoea and field exercise challenge in elite cross-country skiers

BACKGROUND

Methacholine hyperresponsiveness is prevalent in elite athletes. Comparative studies have hitherto been limited to methacholine, eucapnic voluntary hyperpnoea and exercise. This study investigated airway responsiveness to these stimuli as well as to adenosine 5'-monophosphate (AMP) and mannitol, in 58 cross-country ski athletes.

METHODS

Exhaled nitric oxide concentration (F(E)NO), spirometry and bronchial challenge in random order with methacholine, AMP and mannitol were consecutively performed on three study days in the autumn. Specific IgE to eight aeroallergens and a self-completed questionnaire about respiratory symptoms, allergy and asthmatic medication were also performed on day 1. Eucapnic voluntary hyperventilation (EVH) and field exercise tests were randomly performed in 33 of the skiers on two study days in the following winter.

RESULTS

Of 25 (43%) skiers with airway hyperresponsiveness (AHR), 23, five and three skiers were hyperresponsive to methacholine, AMP and mannitol, respectively. Methacholine hyperresponsiveness was more prevalent in subjects without asthma-like symptoms. The F(E)NO was not significantly different in skiers with and without methacholine hyperresponsiveness. Four of 14 skiers with and four of 19 skiers without methacholine hyperresponsiveness were hyperresponsive to EVH or exercise challenge. AHR to any stimulus was present in 16 asymptomatic and nine symptomatic skiers. Asthma-like symptoms were not correlated with AHR to any stimulus.

CONCLUSIONS

Methacholine hyperresponsiveness is more common in asymptomatic skiers and is a poor predictor of hyperresponsiveness to mannitol and hyperpnoea. The low prevalence of hyperresponsiveness to indirect stimuli may suggest differences in the pathogenesis of methacholine hyperresponsiveness in elite skiers and non-athletes.

Effect of ciclesonide on bronchial asthma in athletes

BACKGROUND

Although it is well established that the incidence of bronchial asthma is higher in the athlete population than in the general population, little information exists about the efficacy of treatment of bronchial asthma in the athlete population.

OBJECTIVES

We conducted this study with the objective of determining the efficacy of treatment of bronchial asthma in an athlete population living in Niigata Prefecture, Japan.

METHODS

We conducted a retrospective study of bronchial asthma in an athlete population. Athletes diagnosed as having asthma, based on the Global Initiatives for Asthma (GINA) guidelines, who visited the Niigata Institute for Health and Sports Medicine between January 2007 and June 2008 were enrolled in this study. We compared two groups of patients, a group treated with ciclesonide (CIC) alone and another treated with montelukast alone, with the treatment duration lasting at least 3 months in both groups. The CIC or montelukast groups were compared in terms of the clinical symptoms, pulmonary function parameters, and fraction of exhaled nitric oxide (FENO).

RESULTS

There were no significant differences in the sex distribution, age, frequency of symptoms, pulmonary function parameters, or other examination data before treatment between the CIC and montelukast groups. The CIC group tended to show better symptom control and to need fewer changes of treatment than the montelukast group. While improvements of the pulmonary function parameters and FENO values were observed in the CIC group, no significant changes of these parameters were observed in the montelukast group.

CONCLUSIONS

These data suggest that CIC offers greater promise for the control of asthma than montelukast in the athlete population, although further investigation is required.

Environmental conditions, air pollutants, and airway cells in runners: a longitudinal field study

Runners have increased numbers of neutrophils in the airways at rest and after exercise compared with sedentary individuals. The aim of this study was to determine whether Mediterranean seasonal changes in temperature, humidity or airborne pollutants affect the airway cells of runners training outdoors in an urban environment. In nine male amateur runners, cell composition, apoptosis, and inflammatory mediators were measured in induced sputum collected at rest (baseline) and the morning after races held in the fall (21 km), winter (12 km), and summer (10 km). Concentrations of air pollutants were below the alert threshold at all times. Neutrophil differential counts tended to increase after all races (P = 0.055). Apoptosis of neutrophils increased with ozone (P < 0.005) and particulate matter <10 microm (PM10) (P < 0.05) exposure. Bronchial epithelial cell counts were low at all times and weakly correlated with ozone and PM10 concentrations. Apoptotic bronchial epithelial cells increased after all races (P < 0.05). Inflammatory mediators in induced sputum were low at baseline and after the races, and correlated with neutrophil differential counts only at rest. In conclusion, apoptosis of airway cells in runners appears to be affected by both exercise and environmental conditions. Apoptosis of neutrophils increased with exposure to environmental pollutants while apoptosis of bronchial epithelial cells increased after intense exercise. Since no relationship was observed between neutrophil counts and inflammatory mediators 20 h after races, airways inflammation at this time point appears blunted in healthy runners and little affected by exposure to mild seasonal changes and airborne pollutants.

Hyperinsulinemia predicts survival in a hyperglycemic mouse model of critical illness

OBJECTIVES

: The mechanisms by which correcting hyperglycemia with exogenous insulin improves mortality and morbidity in critically ill patients remain unclear. We designed this study to test the hypothesis that relative endogenous insulin deficiency is associated with adverse outcomes in critical illness related to hyperglycemia.

DESIGN

: Prospective controlled animal study.

SETTING

: University research laboratory.

SUBJECTS

: Male C57BL/6J mice, 8-12 wks old.

INTERVENTIONS

: Spontaneously breathing mice were instrumented with chronic indwelling arterial and venous catheters. After a postoperative recovery period, endotoxemia was initiated with intra-arterial lipopolysaccharide (1 mg/kg) in the presence of dextrose infusion (100 microL/hr). Insulin secretion was blocked with diazoxide (2.5-30 mg/kg/day). Mice were monitored continuously for 48 hrs with blood sampled serially for blood glucose and plasma insulin determinations.

MEASUREMENTS AND MAIN RESULTS

: In both saline- and glucose-infused mice, lipopolysaccharide administration induced transient hemodynamic instability without significant impact on mortality. In the saline-infused group, lipopolysaccharide administration caused a transient reduction in blood glucose and in circulating insulin. However, in glucose-infused mice, lipopolysaccharide induced a large and unexpected increase in circulating insulin without significant alteration in blood glucose. Blockade of insulin secretion in response to lipopolysaccharide in the presence of exogenous glucose precipitated marked hyperglycemia and resulted in >90% mortality. In a subanalysis of animals matched for the degree of hyperglycemia, nonsurvivors had markedly lower insulin levels compared with survivors (3.5 +/- 0.8 ng/dL vs. 9.3 +/- 1.4 ng/dL; p < .004).

CONCLUSIONS

: Endogenous insulin deficiency in the face of hyperglycemia is associated with mortality in a mouse model of lipopolysaccharide-induced critical illness.

High extracellular induced sputum haem oxygenase-1 in sarcoidosis and chronic beryllium disease

BACKGROUND

Sarcoidosis and chronic beryllium disease (CBD) are inflammatory conditions in which oxidative stress state may be crucial for disease outcome. This study compares haem oxygenase-1 (HO-1) extracellular activity for the first time in patients with sarcoidosis or CBD and in healthy controls.

MATERIALS AND METHODS

Induced sputum was recovered using a standard protocol. Pulmonary function tests (PFT) were performed by conventional methods. T lymphocyte subsets (CD4 and CD8) were measured by flow activated cell shorter (FACS). The HO-1 and nitrite levels were measured by a bilirubin-biliverdin reductase-dependent reaction and Greiss reaction respectively. Ferritin and iron levels were measured by enzymatic reaction and chemiluminometric immunoassay respectively.

RESULTS

The mean percentage of lymphocytes was significantly higher in the 36 sarcoid patients compared with that in the 17 controls (P=0.001). The mean CD4/CD8 ratio was significantly higher in the sarcoid and the 10 CBD patients compared to that in controls (P=0.000 and 0.002 respectively), as was the mean HO-1 activity (P=0.045 and 0.041 respectively). The HO-1 activity did not differ with the sarcoidosis stage. The HO-1 level and PFT parameters were negatively correlated. The differences in mean nitrite, ferritin and iron levels were non-significant between the three groups. The HO-1 and ferritin levels were correlated (P=0.008).

CONCLUSIONS

We succeeded in non-invasively measuring the activity of HO-1 from cells of airways in spite of its being an intracellular enzyme. The HO-1 levels in sarcoidosis and CBD were abnormally elevated.

The respiratory health of swimmers

Regular physical activity is recognized as an effective health promotion measure. Among various activities, swimming is preferred by a large portion of the population. Although swimming is generally beneficial to a person's overall health, recent data suggest that it may also sometimes have detrimental effects on the respiratory system. Chemicals resulting from the interaction between chlorine and organic matter may be irritating to the respiratory tract and induce upper and lower respiratory symptoms, particularly in children, lifeguards and high-level swimmers. The prevalence of atopy, rhinitis, asthma and airway hyper-responsiveness is increased in elite swimmers compared with the general population. This may be related to the airway epithelial damage and increased nasal and lung permeability caused by the exposure to chlorine subproducts in indoor swimming pools, in association with airway inflammatory and remodelling processes. Currently, the recommended management of swimmers' respiratory disorders is similar to that of the general population, apart from the specific rules for the use of medications in elite athletes. Further studies are needed to better understand the mechanisms related to the development or worsening of respiratory disorders in recreational or competitive swimmers, to determine how we can optimize treatment and possibly help prevent the development of asthma.

Sex differences in pulmonary function during exercise

Structural and hormonal sex differences are known to exist that may influence the pulmonary system's response to exercise. Specifically, women tend to show reduced lung size, decreased maximal expiratory flow rates, reduced airway diameter, and a smaller diffusion surface than age- and height-matched men. Additionally, ovarian hormones, namely progesterone and estrogen, are known to modify and influence the pulmonary system. These differences may have an effect on airway responsiveness, ventilation, respiratory muscle work, and pulmonary gas exchange during exercise. Recent evidence suggests that during exercise, women demonstrate greater airway hyperresponsiveness and expiratory flow limitation, increased work of breathing, and, perhaps, greater exercise-induced arterial hypoxemia compared with men. The consequence of these pulmonary effects may influence exercise capacity.

Airway injury as a mechanism for exercise-induced bronchoconstriction in elite athletes

Exercise-induced bronchoconstriction (EIB) is a consequence of evaporative water loss in conditioning the inspired air. The water loss causes cooling and dehydration of the airway surface. One acute effect of dehydration is the release of mediators, such as prostaglandins, leukotrienes, and histamine, that can stimulate smooth muscle, causing contraction and a change in vascular permeability. Inspiring cold air increases dehydration of the surface area and causes changes in bronchial blood flow. This article proposes that the pathogenesis of EIB in elite athletes relates to the epithelial injury arising from breathing poorly conditioned air at high flows for long periods of time or high volumes of irritant particles or gases. The evidence to support this proposal comes from many markers of injury. The restorative process after injury involves plasma exudation and movement of cells into the airways, a process repeated many times during a season of training. This process has the potential to expose smooth muscle to a wide variety of plasma- and cell-derived substances. The exposure to these substances over time can lead to an alteration in the contractile properties of the smooth muscle, making it more sensitive to mediators of bronchoconstriction. It is proposed that cold-weather athletes have airway hyperresponsiveness (AHR) to pharmacologic agents as a result of epithelial injury. In those who are allergic, AHR can also be expressed as EIB. The role of beta(2)-receptor agonists in inhibiting and enhancing the development of AHR and EIB is discussed.

Mechanisms of asthma in Olympic athletes--practical implications

Athletes' symptoms may only occur in extreme conditions, which are far from normal. Exercise may increase ventilation up to 200 l/min for short periods in speed and power athletes, and for longer periods in endurance athletes such as swimmers and cross-country skiers. Increasing proportions of young athletes are atopic, i.e. they show signs of IgE-mediated allergy which is, along with the sport event (endurance sport), a major risk factor for asthma and respiratory symptoms. Mechanisms in the etiology and clinical phenotypes vary between disciplines and individuals, and it may be an oversimplification to discuss athlete's asthma as a distinct and unambiguous disease. Nevertheless, the experience on Finnish Olympic athletes suggests at least two different clinical phenotypes, which may reflect different underlying mechanisms. The pattern of 'classical asthma' is characterized by early onset childhood asthma, methacholine responsiveness, atopy and signs of eosinophilic airway inflammation, reflected by increased exhaled nitric oxide levels. Another distinct phenotype includes late onset symptoms (during sports career), bronchial responsiveness to eucapnic hyperventilation test, but not necessarily to inhaled methacholine, and a variable association with atopic markers and nitric oxide. A mixed type of eosinophilic and neutrophilic airway inflammation seems to affect especially swimmers, ice-hockey players, and cross-country skiers. The inflammation may represent a multifactorial trauma, in which both allergic and irritant mechanisms play a role. There is a significant problem of both under- and overdiagnosing asthma in athletes and the need for objective testing is emphasized. Follow-up studies are needed to assess the temporal relationship between asthma and competitive sporting, taking better into account individual disposition, environmental factors (exposure), intensity of training and potential confounders.

Effects of exercise training and montelukast in children with mild asthma

PURPOSE

Data from the general population suggest that habitual exercise decreases bronchial responsiveness, but the possible role of exercise in asthmatics is undefined. The leukotriene receptor antagonist montelukast decreases bronchial responsiveness and exercise-induced symptoms in asthmatic children. This randomized study in children with mild asthma evaluated the combined effects of aerobic training for 12 wk and montelukast or placebo on bronchial responsiveness (BHR) to methacholine, exercise-induced bronchoconstriction (EIB), inflammatory markers in exhaled breath condensate (EBC), and asthma exacerbations.

METHODS

Fifty children (mean age +/- SD: 10.2 +/- 2.4 yr) with mild stable asthma were randomly assigned to placebo (N = 25) or montelukast (N = 25). Before and after training, we assessed BHR and EIB and markers of airway inflammation-that is, exhaled nitric oxide (eNO), pH, and cysteinyl-leukotriene concentration-in EBC.

RESULTS

Training increased maximal workload and peak minute ventilation. After training, the methacholine dose causing a 20% fall in FEV1 (PD20) increased in both groups. A decreased slope of FEV1 decline at increasing methacholine dose was found only in montelukast-treated children. EIB prevalence halved after training in both groups (EIB + children, placebo group: 10 pretraining, 4 posttraining; EIB + children, montelukast group: 8 pretraining, 5 posttraining; P < 0.05 by chi on all children). Resting eNO was unaffected, whereas the pH of EBC decreased after training in both groups. Cysteinyl-leukotriene concentrations were low in most children at both times. During training, montelukast-treated children showed fewer asthma exacerbations compared with the same period of the previous year.

CONCLUSIONS

In children with mild stable asthma, exercise training decreased bronchial responsiveness to methacholine. Montelukast also decreased bronchial reactivity (FEV1 slope) and protected against exacerbations, suggesting a beneficial synergistic action of these two interventions in mild asthma.