Recurrent Airway Obstruction Research Articles

Non-genomic action of beclomethasone dipropionate on bronchoconstriction caused by leukotriene C4 in precision cut lung slices in the horse

BackgroundGlucocorticoids have been proven to be effective in the therapy of recurrent airway obstruction (RAO) in horses via systemic as well as local (inhalative) administration. Elective analysis of the effects of this drug on bronchoconstriction in viable lung tissue offers an insight into the mechanism of action of the inflammatory cascade occurring during RAO which is still unclear. The mechanism of action of steroids in treatment of RAO is thought to be induced through classical genomic pathways. We aimed at electively studying the effects of the glucocorticoid beclomethasone dipropionate on equine precision-cut lung slices (PCLS).PCLS were used to analyze ex-vivo effects of beclomethasone on inhibiting bronchoconstriction in the horse. The inhibiting effect was measured through instillation of a known mediator of inflammation and bronchoconstriction, leukotriene C4. For this, the accessory lobes of 13 horses subjected to euthanasia for reasons unrelated to the respiratory apparatus were used to obtain viable lung slices.ResultsAfter 30 minutes of PCLS incubation, beclomethasone showed to significantly inhibit the contraction of the bronchioles after instillation with leukotriene C4. The EC50 values of the two contraction curves (LTC4 with and without BDP) differed significantly from each other (p = 0.002). The possibility of a non-genomic rapid mechanism of action seems likely since transcriptional activities require a longer lag period.ConclusionsIn human neuroendocrinology, high levels of glucocorticoids have been proven to function via a non-genomic mechanism of membrane receptors. The concentration of beclomethasone used on the lung slices in our study can be considered as high. This allows speculation about similar rapid non-genomic mechanisms of high-dosage inhaled glucocorticoids in the lower airways of horses. However, further assessment on a molecular basis is needed to confirm this.

Potential Role of Adult Stem Cells in Obstructive Sleep Apnea

Adult stem cells are undifferentiated cells that can be mobilized from the bone marrow or other organs, home into injured tissues, and differentiate into different cell phenotypes to serve in a repairing capacity. Furthermore, these cells can respond to inflammation and oxidative stress by exhibiting immunomodulatory properties. The protective and reparative roles of mesenchymal stem cells (MSCs), very small embryonic-like stem cells (VSELs), and endothelial progenitor cells (EPCs) have primarily been examined and characterized in auto-immune and cardiovascular diseases. Obstructive sleep apnea (OSA) is a very prevalent disease (4–5% of adult population and 2–3% of children) characterized by an abnormal increase in upper airway collapsibility. Recurrent airway obstructions elicit arterial oxygen desaturations, increased inspiratory efforts, and sleep fragmentation, which have been associated with important long-term neurocognitive, metabolic, and cardiovascular consequences. Since inflammation, oxidative stress and endothelial dysfunction are key factors in the development of the morbid consequences of OSA, bone marrow-derived stem cells could be important modulators of the morbid phenotype by affording a protective role. This mini-review is focused on the recent data available on EPCs, VSELs, and MSCs in both animal models and patients with OSA.

THE HORSE AS A LARGE ANIMAL MODEL FOR EXTRA-FETAL DERIVED CELL THERAPY OF CHRONIC RESPIRATORY DISEASES

The airway epithelium is subjected to a lifetime exposure to inhaled particles and pathogens that may lead to the development of a variety of infectious and inflammatory respiratory diseases such as chronic bronchitis, asthma and chronic obstructive pulmonary disease. These disorders are typically associated with changes in the architecture of the airway walls,that range from epithelial structure remodeling to complete denudation of the basement membrane. The repair of injuries and the regeneration of the epithelial structure involve stem and progenitor cells. Although both secretory and basal cells are able to proliferate, only basal cells are recently suggested to represent the stem cell (SC) niche of the airway epithelium in human tracheas and bronchi, but the adult secretory cells lose their regeneration potential compared to the fetal secretory cells. For this reason, researchers are considering other sources for exogenous pluripotent SCs for airway tissue engineering. At present, autologous bone marrow and adipose derived MSCs seem to present the most popular SC type used in laryngotracheal tissue engineering. Extra-fetal derived SCs could represent new alternative cell sources for lung regeneration. Investigations of stem cell therapy for murine lung injuries revealed an excellent regeneration potential of extra-fetal derived cells that integrated into the lung and differentiated into pulmonary lineages after injury. Recurrent airway obstruction disease (RAO) in the horse is one of the only naturally occurring diseases in animals that is comparable to bronchial asthma in humans. The anamnestic and reversible nature of equine RAO is similar to some forms of human asthma suggesting a common immunological basis. Based on similarities between human asthma and equine RAO, we propose to use spontaneously RAO affected horses as an animal model in biomedical research. We describe the isolation, in vitro proliferation capacity and labeling of equine extra-fetal derived cells, and preliminary in vivo results indicating that after local injection, labeled cells could be retrieved by bronchoalveolar lavage from selected pulmonary areas.

Correlation and discriminant analysis between clinical, endoscopic, thoracic X-ray and bronchoalveolar lavage fluid cytology scores, for staging horses with recurrent airway obstruction (RAO)

As recurrent airway obstruction (RAO) is progressive and as medical history is frequently unknown by owners, it’s important to suggest a score model to characterize RAO stages for a more accurate diagnosis and treatment. The authors correlated clinical (CS), endoscopic (ES), thoracic X-ray (XRS) and bronchoalveolar lavage fluid (BALFS) scores in horses with RAO, in an attempt to establish relevance of each factor’s contribution for the characterization of RAO stages and to suggest a staging method. Thirty horses with RAO and ten healthy controls were studied. Pearson correlation coefficients were determined between CS, ES, XRS and BALFS. Only significant correlation coefficients (>0.60) were considered. One way variance analyses were used to compare the two groups. A discriminant analysis model was adjusted on the RAO staging method suggested. There was a significant correlation coefficient between the CS cough, nostril flare and abdominal lift, all the mucus ES (0.61–0.84), the XRS interstitial pattern, bronchial radiopacity and thickening and tracheal thickening (0.67–0.78) and the BALFS neutrophil percentages (0.63–0.84). These variables (e.g., cough) which presented a significant correlation coefficient were considered relevant and chosen for a score model to characterize RAO stages. The ten healthy controls were attributed stage 0 and the 30 RAO horses were attributed stages 1 (4 horses), 2 (7 horses), 3 (10 horses) and 4 (9 horses). There was also a significant correlation coefficient between all the relevant variables and the RAO stage (0.61–0.89). Furthermore, discriminant analysis of the RAO staging method showed 92.5% of original grouped cases and 85.0% of cross-validated grouped cases correctly classified, having confirmed major contribution of the same variables that had significant correlation coefficients. Even though further confirmation by lung functional testing is desirable, the significant correlation between relevant variables and RAO stage and the results of RAO staging discriminant analysis support the suggestion of our score model for the characterization of RAO stages.

Sleep and metabolic function

Evidence for the role of sleep on metabolic and endocrine function has been reported more than four decades ago. In the past 30years, the prevalence of obesity and diabetes has greatly increased in industrialized countries, and self-imposed sleep curtailment, now very common, is starting to be recognized as a contributing factor, alongside with increased caloric intake and decreased physical activity. Furthermore, obstructive sleep apnea, a chronic condition characterized by recurrent upper airway obstruction leading to intermittent hypoxemia and sleep fragmentation, has also become highly prevalent as a consequence of the epidemic of obesity and has been shown to contribute, in a vicious circle, to the metabolic disturbances observed in obese patients. In this article, we summarize the current data supporting the role of sleep in the regulation of glucose homeostasis and the hormones involved in the regulation of appetite. We also review the results of the epidemiologic and laboratory studies that investigated the impact of sleep duration and quality on the risk of developing diabetes and obesity, as well as the mechanisms underlying this increased risk. Finally, we discuss how obstructive sleep apnea affects glucose metabolism and the beneficial impact of its treatment, the continuous positive airway pressure. In conclusion, the data available in the literature highlight the importance of getting enough good sleep for metabolic health.

Association analysis of SNPs in the IL21R gene with recurrent airway obstruction (RAO) in Swiss Warmblood horses

Association analysis of SNPs in the IL21R gene with recurrent airway obstruction (RAO) in Swiss Warmblood horses

Cytology Results of Bronchoalveolar Lavage Fluid in Horses with Recurrent Airway Obstruction

Bronchoalveolar lavage is essential in evaluating airway’s status and response to treatment in horses with recurrent airway obstruction. In this study we investigated the changes of bronchoalveolar lavage (BAL) fluid in horses with recurrent airway obstruction undergoing treatment with corticosteroids. Cytologic examination revealed decreased neutrophils percentage in BAL fluid obtained from horses with recurrent airway obstruction at 21 days of treatment after receiving dexamethasone, compared with initial results before treatment. Cytologic examination of BAL fluid provided important data regarding the local inflammatory status of the airways before and after treatment.

The interleukin 4 receptor gene and its role in recurrent airway obstruction in Swiss Warmblood horses

Recurrent airway obstruction (RAO) in horses is the result of an interaction of genetic and environmental factors and shares many characteristics with human asthma. Many studies have suggested that the interleukin-4 receptor gene (IL4R) is associated with this disease, and a QTL region on chromosome 13 containing IL4R was previously detected in one of the two Swiss Warmblood families. We sequenced the entire IL4R gene in this family and detected 93 variants including five non-synonymous protein-coding variants. The allele distribution at these SNPs supported the previously detected QTL signal. Subsequently, we investigated IL4R mRNA expression in bronchoalveolar lavage fluid cells. During exacerbation, IL4R expression was increased in RAO-affected offspring in the implicated family, but not in the other family. These findings support that IL4R plays a role in some cases of RAO.

Glucocorticoid therapy and the risk of equine laminitis

SummaryAlthough glucocorticoids have been used successfully for the treatment of noninfectious inflammatory diseases of horses for more than 35 years, their use has been attended by a fear of the induction of laminitis. This paper reviews the evidence for this fear and the possible mechanisms whereby glucocorticoids could participate in laminitis induction. Although the association of laminitis with elevated serum cortisol in pituitarypars intermediadysfunction suggests that chronic exposure to glucocorticoids may be part of laminitis pathogenesis, review of published reports and databases suggests that glucocorticoid‐induced laminitis is a relatively rare occurrence. However, several of the actions of glucocorticoids are similar to those known to be involved in laminitis pathogenesis. Glucocorticoid administration can induce insulin resistance, lead to vascular dysfunction that potentiates vasoconstriction, and interfere with keratinocyte proliferation and differentiation as well as matrix integrity, all mechanisms that could possibly induce laminitis. Drug formulation, dose and route of administration, and the systemic and hoof disease history of the horse must all be considered when assessing laminitis risk during glucocorticoid treatment. Generally, local glucocorticoid administration presents little risk as does systemic treatment of recurrent airway obstruction without concurrent disease. Caution should be used however in horses that are overweight and/or insulin resistant, or have had a recent bout of acute laminitis of alimentary or endotoxic origin. Overall, however, the risk of laminitis after glucocorticoid treatment, especially local use, is acceptable compared to the many benefits of these drugs.

Age-related tonsillar regrowth in children undergoing powered intracapsular tonsillectomy

Objectives To review our experience with intracapsular tonsillectomy using powered instrumentation (PIT) in the management of tonsillar hypertrophy. Design Retrospective database review of pediatric patients undergoing PIT. Methods The medical records of 636 patients under 11 years of age who underwent PIT performed by the senior author (RFW), predominantly for obstructive sleep disturbance, were reviewed. Data were subsequently analyzed from 559 of these patients for clinical evidence of tonsillar regrowth, post-operative tonsillar hemorrhage, and post-operative dehydration due to pain. Specific information for possible correlation of age at the time of surgery and any increased rate of regrowth was primarily examined. Results There were a total of 33 patients who had clinical evidence of regrowth. Children less than 5 years of age had 5 times the incidence of regrowth ( p < 0.001). Out of the group that exhibited regrowth, 5 patients exhibited evidence of recurrent upper airway obstruction and underwent a complete tonsillectomy. The age of this complete tonsillectomy group ranged from 1.1 to 2.7 years. Out of all patients undergoing PIT, there was 1 incident of delayed post-operative dehydration due to emesis but not due to pain. There were 2 incidents of delayed post-operative tonsillar bleeds. All three complications were self-limited and did not require re-hospitalization. Conclusions PIT is a safe procedure with a small risk of tonsillar regrowth being age related. The incidence of postoperative complications following PIT is relatively low (0.54%).

Comparison of genomic and proteomic data in recurrent airway obstruction affected horses using ingenuity pathway analysis®

BackgroundRecurrent airway obstruction (RAO) is a severe chronic respiratory disease affecting horses worldwide, though mostly in the Northern hemisphere. Environmental as well as genetic factors strongly influence the course and prognosis of the disease. Research has been focused on characterization of immunologic factors contributing to inflammatory responses, on genetic linkage analysis, and, more recently, on proteomic analysis of airway secretions from affected horses. The goal of this study was to investigate the interactions between eight candidate genes previously identified in a genetic linkage study and proteins expressed in bronchoalveolar lavage fluid (BALF) collected from healthy and RAO-affected horses. The analysis was carried out with Ingenuity Pathway Analysis® bioinformatics software.ResultsThe gene with the greatest number of indirect interactions with the set of proteins identified is Interleukin 4 Receptor (IL-4R), whose protein has also been detected in BALF. Interleukin 21 receptor and chemokine (C-C motif) ligand 24 also showed a large number of interactions with the group of detected proteins. Protein products of other genes like that of SOCS5, revealed direct interactions with the IL-4R protein. The interacting proteins NOD2, RPS6KA5 and FOXP3 found in several pathways are reported regulators of the NFκB pathway.ConclusionsThe pathways generated with IL-4R highlight possible important intracellular signaling cascades implicating, for instance, NFκB. Furthermore, the proposed interaction between SOCS5 and IL-4R could explain how different genes can lead to identical clinical RAO phenotypes, as observed in two Swiss Warmblood half sibling families because these proteins interact upstream of an important cascade where they may act as a functional unit.

Immunostimulation of bronchoalveolar lavage cells from recurrent airway obstruction-affected horses by different CpG-classes bound to gelatin nanoparticles

Recurrent airway obstruction (RAO) in horses has become a common problem in stabled horses in industrialized countries and deserves new therapeutic strategies. CpG-oligodeoxynucleotides (CpG-ODNs) were developed as effective immunostimulating agents to induce a Th2/Th1 shift. These agents showed a beneficial therapeutic effect in allergic diseases with predominant Th2 immunoresponse. CpG-ODN delivery by gelatin nanoparticles (GNPs) resulted in enhanced cellular uptake in murine and human in vitro studies and was a starting point for the present trial. The aim of this study was to identify an optimal stimulating CpG motif in horses with regard to species specificity on equine bronchoalveolar lavage (BAL) cells, in terms of a possible specific immunomodulation effect (Th2/Th1 shift) by used CpG-ODN. Accordingly, GNPs were evaluated as a delivery system to improve CpG-ODN immunostimulation in equine BAL cells. BAL fluid (BALF) was obtained from seven horses with moderate RAO and from four healthy horses and was subsequently incubated with five different CpG-ODN sequences (from A-, B- and C-class) and one ODN without any CpG motif. Release of three key cytokines (IL-4, IL-10 and IFN-γ) was quantified by ELISA to detect an allergy mediated Th2 immunoresponse (IL-4) as well as a proinflammatory Th1 response (IFN-γ). Due to its specific anti-inflammatory and anti-allergic effects, IL-10 was considered as a beneficial agent in pathophysiology of RAO. Results showed a significant upregulation of IL-10 and IFN-γ on the one hand and a downregulation of IL-4 on the other hand in RAO affected horses. Cell cultures from healthy horses had a significantly stronger response in cytokine release to all the applied stimuli in contrast to RAO derived cells. Comparing all five CpG sequences, A-class 2216 significantly showed the highest immunomodulatory effects on equine BALF cells and, hence, was chosen for follow-up preliminary clinical studies.

Diagnostic Approaches for the Assessment of Equine Chronic Pulmonary Disorders

Even though the respiratory system is one of the most accessible organs for diagnostic testing, it is not always easy to define chronic lower airway disease in the horse. Diagnostic procedures performed by first opinion veterinarians in the field are often restricted to taking the history and performing clinical examination. Respiratory tract endoscopy, tracheal or bronchoalveolar lavage, and blood sampling are sometimes used but other specific ancillary examinations are seldom performed in stable settings. Therefore, our objectives were to evaluate the diagnostic value of different techniques and examination types routinely used in the diagnostic workup of chronic equine lower airway cases in both stable and clinical circumstances. Another aim of this study was to estimate the prevalence of different chronic pulmonary disorders among horses admitted to a Hungarian referral clinic. According to the conditional inference tree method, age of the horse, history, clinical examination, respiratory tract endoscopy, and bronchoalveolar lavage cytology proved to be the most valuable tools to define pathology. It was also concluded that in 22% of cases, more specific ancillary diagnostic modalities, unavailable for the field veterinarian, were needed to establish the final diagnosis. According to our study, the most frequently diagnosed chronic pulmonary disorders in Hungary are of noninfectious origin, principally recurrent airway obstruction. Regardless of the cause, and interestingly including recurrent airway obstruction as well, these diseases occur primarily during the warm months.

Inhalation with NDS27 attenuates pulmonary neutrophilic inflammation in recurrent airway obstruction

RECURRENT airway obstruction (RAO) or heaves is a chronic respiratory disease that affects mature horses. It is characterised by neutrophilic inflammation and delayed neutrophilic apoptosis (Turlej and others 2001) leading...

Epiglottic abnormalities in mature nonracehorses: 23 cases (1990–2009)

To identify history, clinical signs, endoscopic findings, treatment, and outcome of mature (> 8 years old) nonracehorses with epiglottic abnormalities. Retrospective case series. 23 horses with an epiglottic abnormality. Medical records of horses examined between 1990 and 2009 because of an epiglottic abnormality were reviewed to obtain information on signalment, history, clinical signs, clinical examination findings, upper airway endoscopic findings, diagnosis, surgical procedure, clinical management, postoperative care, and outcome. Mean ± SD age was 16 ± 6 years (range, 9 to 30 years). Sixteen of the 23 (70%) horses had a primary complaint of a chronic cough. Thirteen (57%) horses had epiglottic entrapment, 7 (30%) had a subepiglottic granuloma, and 3 (13%) had a subepiglottic cyst. All 23 horses were treated surgically, with 1 (4%) requiring further surgical treatment. Follow-up examinations and conversations with owners indicated resolution of the primary complaint in 17 of the 23 (74%) horses, with 4 (24%) requiring prolonged medical treatment because of postoperative subepiglottic inflammation. Of the 6 horses without complete resolution, 4 (67%) had signs of recurrent airway obstruction and 2 (33%) developed persistent dorsal displacement of the soft palate following laryngotomy and subepiglottic membrane resection. Results suggested that coughing is a common complaint in mature nonracehorses with epiglottic abnormalities. Therefore, upper airway endoscopy is recommended in the evaluation of older horses with a cough. Surgical treatment can be beneficial in most horses, with some requiring further postoperative medical treatment.

Evaluation of variations in bronchoalveolar lavage fluid in horses with recurrent airway obstruction

To determine variations in cytologic counts of bronchoalveolar lavage (BAL) fluid attributable to month of collection, first and second aliquots, and left and right lung sites in horses with recurrent airway obstruction (RAO). 5 horses with RAO and 5 healthy horses without respiratory tract disease. Horses were housed in a stable for 5 months prior to and throughout the study. Bronchoalveolar lavage fluid was collected from the right and left lung of each horse 3 times at monthly intervals (February, March, and April). Each BAL fluid collection was performed by use of 2 incremental instillations of 250 mL of isotonic saline (0.9% NaCl) solution in the same bronchial site. Analysis of BAL fluid included volume of BAL fluid recovered, a CBC, and differential cytologic counts. Volume of BAL fluid recovered and cytologic counts did not differ in horses with RAO across time or between right and left lungs, except for the number of mast cells. Horses with RAO had significantly lower volumes of BAL fluid recovered, significantly lower percentages of macrophages and lymphocytes, and significantly higher percentages of neutrophils than did healthy horses. Despite individual variation, all horses with RAO had > 25% neutrophils throughout the study period. Despite variation among horses, BAL fluid cytologic counts were repeatable over short and long periods and samples can be used for longitudinal studies as a diagnostic tool of pulmonary inflammation in horses with RAO.

Increased apoptosis of CD4 and CD8 T lymphocytes in the airways of horses with recurrent airway obstruction

Recurrent airway obstruction (RAO, also known as equine heaves) is an inflammatory condition similar to human asthma caused by exposure of susceptible horses to poorly ventilated stable environments. The disease is characterized by neutrophilic airway inflammation, mucus hypersecretion and reversible bronchoconstriction. This inflammatory process is mediated by several factors, including antibodies, cytokines, resident cells of the airway and inflammatory cellular components that arrive in the respiratory tract. An increasing body of evidence has lent support to the concept that a dysregulation of T cell apoptosis may play a central role in the development of airway inflammation and the associated asthma. Therefore, the aim of this study was to investigate early and late apoptosis of CD4 and CD8 T cell subpopulations obtained from the airways of acute RAO-positive animals after exposure to hay/straw. The percentages of CD4 and CD8 T cells and their associated frequencies of apoptosis were quantified using flow cytometry. Hay/straw exposure induced clinical airway obstruction, airway neutrophilia and increased airway mucus production in RAO-positive horses. In addition, allergen exposure increased the percentage of CD4 T cells in RAO-positive horses as well as the frequency of early and late apoptosis in both CD4 and CD8 lymphocyte subpopulations. These results suggest that the higher frequency of lymphocyte apoptosis may play a role in disease progression of horses afflicted with RAO and may partially explain the characteristic remission of this pathological condition once the allergen source is removed. However, further studies are needed to clarify the role of T cell apoptosis in RAO-affected horses.

Smooth Muscle Proliferation is a Histologic Feature of Airway Remodeling in Summer Pasture Associated Recurrent Airway Obstruction

s / Journal of Equine Veterinary Science 31 (2011) 230-356 246 improves our understanding of the temporal transcriptional responses to exercise in this tissue. The findings clearly suggest that metabolic capacity of entrained muscle should be optimal at times of day that coincide with the training regime.

Acute epiglottitis complicated with pharyngeal abscess and recurrent acute airway obstruction in an adult

Acute epiglottitis is a common condition in children but is a rare entity in adults. Both in children and adults this is a life threatening condition as it can lead to complete airway obstruction. It is therefore vital that this condition is kept in mind when patients, both children and adults are admitted with severe airway obstruction to the emergency room. A case of adult acute epiglottitis complicated with abscess formation is described where timely intervention and correct diagnosis with appropriate treatment saved the life of the patient. Key words: Acute epiglottitis; Acute airway obstruction; Deep neck abscess DOI: 10.4038/slja.v19i1.2872 Sri Lankan Journal of Anaesthesiology Vol.19(1) 2011 pp.47-50

Comparative efficacy of inhaled albuterol between two hand-held delivery devices in horses with recurrent airway obstruction

Studies investigating the clinical efficacy of albuterol administered with the same propellant and commercially available delivery devices in horses with recurrent airway obstruction (RAO) are not currently available. To determine the efficacy of aerosolised albuterol administered to horses with RAO by means of 2 commercially available, hand-held delivery devices. Ten horses with RAO were kept in a dusty environment and fed mouldy hay to induce airway obstruction. Lung mechanics were measured before and after the procedure. ΔP(max) was measured 5 min after administration of 180 µg of albuterol from a pressurised metered dose inhaler, using an aerosol delivery device chosen randomly. This process was repeated every 5 min until maximal bronchodilation was achieved. After a 24 h washout period, lung mechanics data were again collected using the other aerosol delivery device. Aerosolised albuterol induced a significant and rapid bronchodilation in the horses using both aerosol delivery devices. No statistically significant difference in pulmonary function was observed in response to albuterol therapy between the 2 devices. The dose required to achieve 50% of maximal bronchodilation was not statistically different between the 2 devices (173.35 ± 78.35 µg with Device 1 and 228.49 ± 144.99 µg with Device 2, P = 0.26). The decrease in lung resistance tended to be more pronounced after albuterol administration with Device 1 (P = 0.066). Aerosolised albuterol is an effective bronchodilator in horses with recurrent airway obstruction. There is no statistically significant difference between the 2 commercially available aerosol delivery devices in terms of efficacy. Aerosolised albuterol is effectively delivered using currently available devices leading to maximal bronchodilation in horses with RAO at an average dose of 540 µg.