The "choking game": a new craze among Brazilian children and young people. Psychophysiological, behavioral and epidemiological characteristics of 'asphyxial games'. / "Brincadeira do desmaio": uma nova moda mortal entre crianças e adolescentes. Características psicofisiológicas, comportamentais e epidemiologia dos 'jogos de asfixia'.

The 'choking game' is a risk-taking behavior that has spread quickly among children and young people, causing dependence, accidents and even death, including in Brazil. These activities are performed in order to experience fleeting euphoric sensations, attracting numerous participants through the thousands of videos posted on YouTube. The problem of 'asphyxial games' can be observed in the Brazilian digital media, although there is a lack of scientific studies. Through a systematic review of the literature and complementary material, this paper aims to address the 'asphyxial games', warning about the psychophysiological and behavioral effects of these practices, while also presenting international epidemiological data. Sharing this information in academic circles is extremely important given the need to acquire more knowledge on the topic, train professionals and propose preventive measures that raise awareness among children and young people of the potential danger of voluntary fainting. It is equally important to raise awareness among parents and teachers so they can identify the warning signs that children may be engaging in these practices. And finally, it is also necessary to request government support to control exposure to videos that encourage the behavior.

"Brincadeira do desmaio": uma nova moda mortal entre crianças e adolescentes. Características psicofisiológicas, comportamentais e epidemiologia dos 'jogos de asfixia' / The "choking game": a new craze among Brazilian children and young people. Psychophysiological, behavioral and epidemiological characteristics of 'asphyxial games'

Resumo As 'brincadeiras do desmaio' são comportamentos de risco que têm se difundido rapidamente entre crianças e jovens, provocando dependência, acidentes e mesmo mortes, inclusive no Brasil. Estas atividades são realizadas para vivenciarem sensações eufóricas e fugazes, atraindo grande número de adeptos por meio de milhares de vídeos postados no YouTube. A problemática dos 'jogos de asfixia' é observada nas mídias digitais brasileiras, mas carece de estudos científicos. Por meio de revisão sistemática da literatura e de bibliografia complementar, este trabalho objetiva discorrer sobre os 'jogos de asfixia', alertando aos aspectos psicofisiológicos e comportamentais, aos riscos potenciais destas práticas e, também, apresentar dados epidemiológicos internacionais. Compartilhar essas informações no meio acadêmico é de extrema importância dada a necessidade de maiores conhecimentos sobre o tema, de realizar capacitação de profissionais e de propor medidas preventivas que sensibilizem crianças e jovens ao perigo potencial dos desmaios voluntários. Sensibilizar igualmente os pais e professores a atentarem aos sinais decorrentes destas práticas. É também relevante a busca de apoio dos governantes para o controle da divulgação de vídeos incitativos.

Abstract The 'choking game' is a risk-taking behavior that has spread quickly among children and young people, causing dependence, accidents and even death, including in Brazil. These activities are performed in order to experience fleeting euphoric sensations, attracting numerous participants through the thousands of videos posted on YouTube. The problem of 'asphyxial games' can be observed in the Brazilian digital media, although there is a lack of scientific studies. Through a systematic review of the literature and complementary material, this paper aims to address the 'asphyxial games', warning about the psychophysiological and behavioral effects of these practices, while also presenting international epidemiological data. Sharing this information in academic circles is extremely important given the need to acquire more knowledge on the topic, train professionals and propose preventive measures that raise awareness among children and young people of the potential danger of voluntary fainting. It is equally important to raise awareness among parents and teachers so they can identify the warning signs that children may be engaging in these practices. And finally, it is also necessary to request government support to control exposure to videos that encourage the behavior.

Metalloproteinases and their inhibitors are influenced by inhalative glucocorticoid therapy in combination with environmental dust reduction in equine recurrent airway obstruction.

BACKGROUND: Overexpression of matrix-metalloproteinases (MMPs) has been shown to lead to tissue damage in equine recurrent airway obstruction (RAO), as a misbalance with their natural inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), occurs. This favors irreversible pulmonary fibrosis formation. Increased levels of MMPs, TIMPs or altered ratios between them can be used as biomarkers of respiratory disease. We hypothesized that levels of MMPs, TIMPs and their ratios correlate with improvement in clinical findings and bronchoalveolar lavage fluid (BALF) cytology after 10 days of inhalative glucocorticoid therapy and environmental dust reduction (EDR) and may be used to monitor treatment success. Ten horses with a history of RAO participated in a prospective clinical study. Clinical and cytological scoring was performed before and after inhalative therapy using budesonide (1500 µg BID over 10 days) and EDR (bedding of wood shavings and wet hay as roughage). Gelatin zymography was performed for qualitative and semi-quantitative evaluation of MMP-2 and MMP-9 in BALF supernatant, while fluorimetry was used to evaluate MMP-8 activity. Additionally, specific equine ELISA assays were used for quantitative assessment of MMP-2, MMP-9, TIMP-1 and TIMP-2. RESULTS: A significant reduction in the total and several single parameters of the clinical score were found after 10 days of inhalative therapy and EDR. The concentrations of MMP-2, MMP-9, TIMP-1 and TIMP-2 (ELISA) as well as their activities (MMP-2 and MMP-9 zymography and MMP-8 fluorimetry) were significantly decreased after therapy. Significant improvements in MMP-8/TIMP-1 and MMP-8/TIMP-2 ratios were also found, differences between other ratios before and after therapy were insignificant. CONCLUSIONS: Metalloproteinases and their inhibitors, in particular MMP-9 and TIMP-2, are valuable markers for clinical improvement in RAO.

Effect of antigen sensitization and challenge on oscillatory mechanics of the lung and pulmonary inflammation in obese carboxypeptidase E-deficient mice.

Atopic, obese asthmatics exhibit airway obstruction with variable degrees of eosinophilic airway inflammation. We previously reported that mice obese as a result of a genetic deficiency in either leptin (ob/ob mice) or the long isoform of the leptin receptor (db/db mice) exhibit enhanced airway obstruction in the presence of decreased numbers of bronchoalveolar lavage fluid (BALF) eosinophils compared with lean, wild-type mice following antigen (ovalbumin; OVA) sensitization and challenge. To determine whether the genetic modality of obesity induction influences the development of OVA-induced airway obstruction and OVA-induced pulmonary inflammation, we examined indices of these sequelae in mice obese as a result of a genetic deficiency in carboxypeptidase E, an enzyme that processes prohormones and proneuropeptides involved in satiety and energy expenditure (Cpe(fat) mice). Accordingly, Cpe(fat) and lean, wild-type (C57BL/6) mice were sensitized to OVA and then challenged with either aerosolized PBS or OVA. Compared with genotype-matched, OVA-sensitized and PBS-challenged mice, OVA sensitization and challenge elicited airway obstruction and increased BALF eosinophils, macrophages, neutrophils, IL-4, IL-13, IL-18, and chemerin. However, OVA challenge enhanced airway obstruction and pulmonary inflammation in Cpe(fat) compared with wild-type mice. These results demonstrate that OVA sensitization and challenge enhance airway obstruction in obese mice regardless of the genetic basis of obesity, whereas the degree of OVA-induced pulmonary inflammation is dependent on the genetic modality of obesity induction. These results have important implications for animal models of asthma, as modeling the pulmonary phenotypes for subpopulations of atopic, obese asthmatics critically depends on selecting the appropriate mouse model.

Matrix metalloprotease-9 induces transforming growth factor-ß(1) production in airway epithelium via activation of epidermal growth factor receptors.

AIMS: Matrix metalloprotease (MMP)-9 is present in abundance in various chronic airway disorders and is involved in lung remodeling. MMP may cleave membrane-bound precursor proteins and release epidermal growth factor-like ligands that subsequently bind to epidermal growth factor receptor (EGFR). We hypothesized that MMP-9 may stimulate the airway epithelium to produce fibrogenic mediators through activation of membrane-bound receptors. MAIN METHODS: Human airway epithelial cells were grown on air-liquid interface culture inserts. MMP-9 was employed to stimulate the cells. Conditioned medium following MMP-9 stimulation was co-incubated with human lung fibroblasts. KEY FINDINGS: MMP-9 stimulated human airway epithelial cells to produce transforming growth factor (TGF)-ß(1) at both the mRNA and protein level. Using a microarray, increased phosphorylation of EGFR tyrosine kinase (TK) was identified and further confirmed by immunoprecipitation and Western blot analysis. A significant increase in EGF and TGF-α release was observed after MMP-9 had been added for 30min. Protease inhibitor, EGFR monoclonal antibody and EGFR-TK inhibitor blocked this action and subsequent TGF-ß(1) production. Neutralizing antibodies against EGF and TGF-α substantially inhibited TGF-ß(1) production following MMP-9 stimulation. MMP-9-induced TGF-ß(1) production occurred through MAP kinase p44/42 phosphorylation. Selective p44/42 kinase inhibitor UO126 successfully inhibited TGF-ß(1) production. Conditioned medium from epithelial cells treated with MMP-9 significantly induced Smad3 phosphorylation and subsequent fibroblast proliferation after 24h culture. SIGNIFICANCE: These data indicate that MMP-9 induces TGF-ß(1) production in the airway epithelium through the cleavage of EGF and EGF-like ligands and activating EGFR, suggesting potential targets of therapeutic intervention in airway fibrotic disorders.

Measurement of ascorbic acid concentration and glutathione peroxidase activity in biological samples collected from horses with recurrent airway obstruction.

OBJECTIVE: To measure the ascorbic acid (AA) concentration in bronchoalveolar lavage fluid (BALF) and cellular glutathione peroxidase (cGPx) activity in RBCs and WBCs from peripherally obtained blood and in cells from BALF to determine whether differences existed between the 2 major redox systems in recurrent airway obstruction (RAO)-affected and -nonaffected (control) horses and between systemic and local pulmonary responses in the glutathione redox system. ANIMALS: 16 adult horses in pairs: 8 healthy (control) and 8 RAO-affected horses. PROCEDURES: Physical examination data and biological samples were collected from horses before (remission), during, and after (recovery) environmental challenge with dusty straw and hay. At each stage, BALF cell AA concentration and RBC, WBC, and BALF cell cGPx activity were measured. RESULTS: Compared with control horses, RAO-affected horses had significantly higher cGPx activity in RBCs at all points and in WBCs during remission and challenge. The BALF cell cGPx activity was higher in RAO-affected horses during recovery than during remission The BALF cell AA concentration did not differ significantly in control horses at any point, but total and free AA concentrations were significantly lower in RAO-affected horses during the challenge period than during remission and recovery periods. CONCLUSIONS AND CLINICAL RELEVANCE: High cGPx activity suggested this redox system was upregulated during exposure to dusty straw and hay to combat oxidative stress, as AA was depleted in RAO-affected horses. The relative delay and lack of comparative increase in cGPx activity within the local environment (represented by BALF cells), compared with that in RBCs and WBCs, might contribute to disease in RAO-affected horses.

α1-Antitrypsin protease inhibitor MZ heterozygosity is associated with airflow obstruction in two large cohorts.

BACKGROUND: Severe α1-antitrypsin deficiency is a known genetic risk factor for COPD. Heterozygous (protease inhibitor [PI] MZ) individuals have moderately reduced serum levels of α1-antitrypsin, but whether they have an increased risk of COPD is uncertain. METHODS: We compared PI MZ and PI MM individuals in two large populations: a case-control study from Norway (n = 1,669) and a multicenter family-based study from Europe and North America (n = 2,707). We sought to determine whether PI MZ was associated with the specific COPD-related phenotypes of lung function and quantitative CT scan measurements of emphysema and airway disease. RESULTS: PI MZ was associated with a 3.5% lower FEV1/FVC ratio in the case-control study (P = .035) and 3.9% lower FEV1/vital capacity (VC) ratio in the family study (P = .009). In the case-control study, PI MZ also was associated with 3.7% more emphysema on quantitative analysis of chest CT scans (P = .003). The emphysema result was not replicated in the family study. PI MZ was not associated with airway wall thickness or COPD status in either population. Among subjects with low smoking exposure (< 20 pack-years), PI MZ individuals had more severe emphysema on chest CT scan than PI MM individuals in both studies. CONCLUSIONS: Compared with PI MM individuals, PI MZ heterozygotes had lower FEV1/(F)VC ratio in two independent studies. Our results suggest that PI MZ individuals may be slightly more susceptible to the development of airflow obstruction than PI MM individuals.

In vitro inhibition of matrix metalloproteinase activity in tracheal epithelial lining fluid from horses with recurrent airway obstruction.

OBJECTIVE: To evaluate inhibitory effects of synthetic matrix metalloproteinase (MMP) inhibitors in vitro on gelatinolytic and collagenolytic activities in tracheal epithelial lining fluid (TELF) of horses with recurrent airway obstruction (RAO). ANIMALS: 10 horses with RAO and 5 healthy control horses. PROCEDURES: Substrate-based functional assays, collagen I and gelatin degradation, were used to measure endogenous collagenolytic and gelatinolytic activities in TELF. In vitro inhibition of MMP activity in TELF with 2 chemically modified tetracyclines (CMTs; CMT-3 and CMT-8) and 2 bisphosphonates (BPs; zoledronate and pamidronate) was evaluated. RESULTS: CMT-3, CMT-8, zoledronate, and pamidronate in a dose-dependent manner inhibited TELF type I collagenolytic and gelatinolytic activities, although no complete inhibition of TELF type I collagenolytic and gelatinolytic activities was achieved with the inhibitor concentrations of 25 to 500 microM tested. The CMTs inhibited pathologically induced collagen I degradation more effectively than BPs. Of the tested CMTs, CMT-3 was the most effective inhibitor of gelatinolytic activity, and the efficiency of CMT-3 corresponded with that of the BPs. CONCLUSIONS AND CLINICAL RELEVANCE: An increase in MMP activity in the equine respiratory tract may potentially be inhibited by administration of CMTs or BPs. Distinct synthetic MMP inhibitors may eventually provide an additional means for pharmacologic treatment by decreasing ongoing active tissue destructive inflammation associated with chronic lung disease. The MMP inhibitors such as CMTs and BPs that are targeted to solely inhibit a pathologic increase in MMP activities provide the advantage of minimal adverse effects that are characteristics of other excessively potent MMP inhibitors.

Correlation of systemic superoxide dismutase deficiency to airflow obstruction in asthma.

RATIONALE: Increased oxidative stress and decreased superoxide dismutase (SOD) activity in the asthmatic airway are correlated to airflow limitation and hyperreactivity. We hypothesized that asthmatic individuals with higher levels of oxidative stress may have greater loss of SOD activity, which would be reflected systemically in loss of circulating SOD activity and clinically by development of severe asthma and/or worsening airflow limitation. METHODS: To investigate this, serum SOD activity and proteins, the glutathione peroxidase/glutathione antioxidant system, and oxidatively modified amino acids were measured in subjects with asthma and healthy control subjects. RESULTS: SOD activity, but not Mn-SOD or Cu,Zn-SOD protein, was lower in asthmatic serum as compared with control, and activity loss was significantly related to airflow limitation. Further, serum SOD activity demonstrated an inverse correlation with circulating levels of 3-bromotyrosine, a posttranslational modification of proteins produced by the eosinophil peroxidase system of eosinophils. Exposure of purified Cu,Zn-SOD to physiologically relevant levels of eosinophil peroxidase-generated reactive brominating species, reactive nitrogen species, or tyrosyl radicals in vitro confirmed that eosinophil-derived oxidative pathways promote enzyme inactivation. CONCLUSION: These findings are consistent with greater oxidant stress in asthma leading to greater inactivation of SOD, which likely amplifies inflammation and progressive airflow obstruction.

Inhibition of obliterative airway disease development in murine tracheal allografts by matrix metalloproteinase-9 deficiency.

This study was designed to define the roles of matrix metalloproteinase (MMP)-2 and MMP-9 in obliterative airway disease (OAD) in heterotopic murine tracheal allografts, considered a suitable animal model for chronic lung allograft rejection. BALB/c tracheal allografts were transplanted into MMP-2-deficient (-/-) and MMP-9-/- mice. Also, wild-type recipients were treated with doxycycline, a nonspecific MMP inhibitor. After 10, 20 and 30 days, allografts were analyzed for OAD development, intragraft levels of MMP-2 and MMP-9 and the frequency and cytokine/chemokine production profile of alloreactive T cells. Allografts transplanted into wild-type mice developed OAD lesions within 30 days. These allografts revealed significant upregulation of both MMP-2 and MMP-9. Allografts transplanted into MMP-9-/- and doxycycline-treated recipients did not develop OAD. In contrast, allografts transplanted into MMP-2-/- mice developed OAD lesions with normal kinetics. Interestingly, MMP-9-/- recipients showed an enhanced T cell alloreactivity associated with an abnormal profile of cytokine/chemokine production. The enhanced T cell alloreactivity in MMP-9-/- mice was mediated by enhanced dendritic cell stimulatory capacity as well as enhanced T cell responsive capacity. These results suggest that MMP-9 plays an important role in the pathogenesis of OAD and may represent a target for the therapeutic intervention of chronic lung allograft rejection.

Airway obstruction correlates with collagenase-2 (MMP-8) expression and activation in bronchial asthma.

Matrix metalloproteinases (MMPs) contribute to extracellular matrix and basement membrane degradation in asthma. The present study analyzed molecular forms and degree of activation and expression of MMP-8 in bronchoalveolar lavage fluid (BALF), BALF cells, and bronchial tissue specimens from 14 steroid-naive asthma patients, 13 uncontrolled severe asthma patients, 13 controlled asthma patients, and 14 healthy subjects by Western immunoblotting, immunohistochemistry, and in situ hybridization. Immunohistochemistry and in situ hybridization revealed a prominent MMP-8 immunoreactivity in submucosal inflammatory, glandular, and shed, but not in intact bronchial epithelial cells of asthma patients. In BALF cytospins, both MMP-8 protein and mRNA expression were observed in epithelial cells, macrophages, and polymorphonuclear leukocytes (PMNs). MMP-8 was present in BALFs asthma patients in complex, pro- and active PMN-type, and pro- and active non-PMN-type forms. BALF MMP-8 was significantly converted to active form only in BALFs from steroid-naive and uncontrolled severe asthma patients, but not in BALFs from well-controlled asthma patients or healthy controls. A significant inverse correlation between BALF MMP-8 levels and FEV1 (r = -0.283, p = 0.04), and BALF activated MMP-8 forms and FEV1 (r = -0.427, p = 0.001) was detected. Overall, these data suggest that MMP-8 and its activation has an important role in the airway destruction, healing, remodeling, and treatment response in asthma.

Neuroepithelial bodies: a morphologic substrate for the link between neuronal nitric oxide and sensitivity to airway hypoxia?

Currently, the significance of nitric oxide (NO) in the respiratory tract is a matter of great interest because NO is believed to play a major role in the physiological regulation of airway function but also in lung pathology. What is especially intriguing with respect to the present investigation, are reports that the pulmonary expression of neuronal NO synthase (nNOS) is altered as a result of airway hypoxia. We examined the possible relationship between intrapulmonary nitrergic structures and pulmonary neuroepithelial bodies (NEBs), chemoreceptor-like epithelial cell groups that are known to have all necessary components for oxygen perception. Tyramide-enhanced immunostaining for nNOS was combined with known markers for NEBs in an ontogenetic study of rat lungs. From postnatal day 2 onward, nNOS-immunoreactive (-IR) neuronal cell bodies, present mainly in the lamina propria at all levels of intrapulmonary airways, were seen to give rise to remarkable intraepithelial terminal arborizations that invariably colocalized with NEBs. nNOS immunoreactivity was absent from the vagal calbindin D28k(CB) -IR and the spinal calcitonin gene-related peptide(CGRP) -IR extrinsic sensory nerve fiber populations that our group reported earlier to selectively contact NEBs. Quantitative analysis showed that all NEBs receiving nNOS-IR terminals were also contacted by CGRP-IR nerve fibers, whereas approximately 55% were additionally contacted by CB-IR nerves. The reported nitrergic neurons did not express the cholinergic marker vesicular acetylcholine transporter and were always surrounded by a basket of CGRP-IR nerve terminals. In conclusion, part of the pulmonary NEBs selectively receive extensive nitrergic nerve terminals that originate from intrinsic neurons. Together with literature data on lung physiology and pharmacology, some interesting suggestions for the functional significance of the association between pulmonary CGRP-IR NEBs, nNOS-IR neurons, and CGRP-IR afferents described in the present study, are discussed.

Sputum levels of metalloproteinase-9 and tissue inhibitor of metalloproteinase-1, and their ratio correlate with airway obstruction in lung transplant recipients: relation to tumor necrosis factor-alpha and interleukin-10.

BACKGROUND: Chronic transplant rejection is characterized by progressive narrowing of small airways caused by matrix remodeling and fibrosis. Matrix-metalloproteinases (MMPs) and their inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), are involved in the turnover of extracellular matrix. METHODS: To clarify the contribution of MMPs and TIMPs to airway inflammation in patients after lung transplantation (LTx), we used enzyme immunoassays to measure induced sputum concentrations of MMP-9, TIMP-1, and controlling cytokines tumor necrosis factor (TNF)-alpha and interleukin (IL)-10 of 30 LTx patients and 15 control subjects. RESULTS: Sputum concentrations of MMP-9, TIMP-1, the MMP-9:TIMP-1 ratio, and TNF-alpha were higher in LTx patients than in control subjects (p < 0.04, all comparisons). The MMP-9, MMP-9:TIMP-1, and TNF-alpha levels were also significantly higher in LTx patients with chronic rejection compared with those with stable organ function (p < 0.03, all comparisons), whereas IL-10 levels were higher in the latter group (p = 0.05). In all LTx patients, MMP-9 and the MMP-9:TIMP-1 ratio were negatively correlated with forced expiratory volume in 1 second values (rho = -0.47, p = 0.01, and rho = -0.53, p = 0.003, respectively). We found that MMP-9 positively correlated with sputum neutrophils and TNF-alpha whereas MMP-9 and TIMP-1 did not correlate with IL-10. CONCLUSIONS: These data underline the possible contribution of proteases such as MMP-9 to chronic transplant rejection, and suggest that an imbalance of MMP-9 and TIMP-1 may be involved in the pathogenesis of airway obstruction after LTx. We found that MMP-mediated inflammation seems to be controlled by TNF-alpha whereas IL-10 might elicit anti-inflammatory effects through different pathways.

Time course of diaphragm injury and calpain activity during resistive loading.

The purpose of this study was to determine the time course of arterial blood gas (ABG) deterioration, increased calpain activity, and diaphragm injury during 4 d of resistive loading. Adult Sprague- Dawley rats were divided into control (C) animals and groups that were tracheally banded (TB) for 1 d (TB1), 2 d (TB2), 3 d (TB3), and 4 d (TB4). In TB rats, the carotid artery was cannulated and the trachea was banded during anesthesia. TB groups (TB1, TB2, TB3, and TB4) had a 67% smaller internal cross-sectional area of the trachea than did C animals. ABG samples from awake rats showed a decreased arterial oxygen tension (Pa(O(2))) and a respiratory acidosis in the TB1, TB2, and TB3 groups. Calpain activity was higher in the diaphragm of TB than of C rats; calpainlike activities in soluble fractions of diaphragm tissue were greater in all TB groups than in C rats, whereas those in bound fractions were greater in the TB2 and TB3 groups. Point counting of hematoxylin and eosin-stained cross-sections showed that the area fraction (A(A)) of normal diaphragm was lower and the A(A) of abnormal muscle and connective tissue was higher in TB3 than in C rats. Increased resistive loading induced by tracheal banding was associated with hypercapnic ventilatory failure, increased calpain activity, and diaphragm injury. Ventilatory failure in response to resistive loading may be due to diaphragm injury and/or to decreased minute ventilation.

Elevated nitric oxide synthase activity concurrent with antigen-induced airway hyperresponsiveness in rats.

To characterize the airway nitric oxide synthase (NOS) activities concurrent with airway hyperresponsiveness (AHR), a common feature of allergic asthma, the NOS activities of airway tissue homogenates from the antigen-induced AHR rats were determined by the ability of tissue homogenates to convert L-arginine to L-citrulline (Cit). A significantly higher level of total NOS activities was found in homogenates from the AHR rats (19.9 +/- 1.3 pmol Cit/min/mg protein) compared to those from sensitized control and normal control groups (9.8 +/- 1.2 and 8.8 +/- 1.2 pmol Cit/min/mg protein, respectively; P < .01). The nitrite concentration in bronchoalveolar lavage fluids, which indicates the in vivo generation of NO in airways, from the AHR rats (7.40 +/- 0.71 microM) was significantly greater than that from nonsensitized normal animals (1.45 +/- 1.12 microM, P < .01). Although the protein levels of endothelial (eNOS) and neuronal type NOS (nNOS) determined by immunoblotting were within normal levels, the amount of inducible NOS (iNOS) protein was markedly and significantly elevated in airway tissue homogenates from the AHR rats. Immunohistochemical staining of airway tissues with specific antibody against iNOS demonstrated a distinct localization of iNOS on epithelial cells and infiltrated inflammatory cells in the bronchi of the hyperresponsive rats, but only negligible staining of epithelia was observed in the nonsensitized normal group. No difference in constitutive NOS (eNOS and nNOS) localization was observed between groups. The present findings indicate that the NOS activities in airway tissues are elevated in antigen-induced AHR rats, which is mainly derived from the induction of iNOS in the airways. Downregulation of constitutive eNOS and nNOS is not found in this animal model of AHR.

New phosphodiesterase inhibitors as therapeutics for the treatment of chronic lung disease.

Phosphodiesterase 4 (PDE4) is a member of the growing family cyclic AMP and cyclic GMP. Earliest described inhibitors of PDE4, such as rolipram, demonstrate marked anti-inflammatory and bronchodilatory effects in vitro and in vivo. The clinical utility of these earlier compounds was limited by their propensity to elicit gastrointestinal side effects. This has led to an extensive effort to identify novel PDE4 inhibitors that maintain the anti-inflammatory activity and bronchodilatory activity of rolipram but with a reduced potential to produce side effects. This article summarizes the evidence supporting the utility of selective PDE4 inhibitors in the treatment of asthma and chronic obstructive pulmonary disease, discusses the recent results obtained in clinical trials with second-generation inhibitors, and presents two approaches designed to identify additional novel selective PDE4 inhibitors.

Sputum metalloproteinase-9/tissue inhibitor of metalloproteinase-1 ratio correlates with airflow obstruction in asthma and chronic bronchitis.

Asthma and chronic bronchitis are inflammatory diseases with extracellular matrix (ECM) remodeling and collagen deposition. Collagen homeostasis is controlled by metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). We evaluated MMP and TIMP balance in induced sputum of 10 control, 31 untreated asthmatic, and 16 chronic bronchitic subjects. We first performed zymographic analysis to identify the profile of MMPs. Zymography revealed a similar MMPs profile in all populations studied and that MMP-9 was the major enzyme released. We then measured, using enzyme immunoassay, the concentrations of MMP-9 and of its inhibitor TIMP-1 and evaluated whether airflow limitation may be associated with an imbalance between these enzymes. MMP-9 and TIMP-1 concentrations were greater in sputum of patients with asthma and chronic bronchitis than in control subjects. The molar ratio between MMP-9 and TIMP-1 was lower in asthmatics and chronic bronchitics than in control subjects, and positively correlated with FEV1 values. In asthma, MMP-9 levels were significantly correlated with the number of macrophages and neutrophils. This study shows that airway inflammation in asthma and chronic bronchitis is associated with an imbalance between MMP-9 and TIMP-1 which may have a role in the pathogenesis of ECM remodeling and airflow obstruction.

beta-Hexosaminidases: potent mitogens of airway smooth muscle.

beta-Hexosaminidases A & B, inflammatory marker enzymes, are mannosyl-rich glycoproteins that are implicated in acute asthma. At physiologically and pathologically relevant concentrations (nM), beta-Hexosaminidases act as potent mitogens of bovine airway smooth muscle cells. This mitogenic action is mediated via 175 kD mannose recognizing receptors that have been isolated from bovine airway smooth muscle cells and human bronchial smooth muscle. There seems to be an involvement of multiple signal transduction pathways in this process and this mitogenic effect is cell density dependent. Moreover, beta-Hexosaminidases are protease resistant. Thus, beta-Hexosaminidases may serve as key inflammatory mediators critical to airway remodeling process.