A microphysiological model of the bronchial airways reveals the interplay of mechanical and biochemical signals in bronchospasm.

In asthma, the contraction of the airway smooth muscle and the subsequent decrease in airflow involve a poorly understood set of mechanical and biochemical events. Organ-level and molecular-scale models of the airway are frequently based on purely mechanical or biochemical considerations and do not account for physiological mechanochemical couplings. Here, we present a microphysiological model of the airway that allows for the quantitative analysis of the interactions between mechanical and biochemical signals triggered by compressive stress on epithelial cells. We show that a mechanical stimulus mimicking a bronchospastic challenge triggers the marked contraction and delayed relaxation of airway smooth muscle, and that this is mediated by the discordant expression of cyclooxygenase genes in epithelial cells and regulated by the mechanosensor and transcriptional co-activator Yes-associated protein. A mathematical model of the intercellular feedback interactions recapitulates aspects of obstructive disease of the airways, which include pathognomonic features of severe difficult-to-treat asthma. The microphysiological model could be used to investigate the mechanisms of asthma pathogenesis and to develop therapeutic strategies that disrupt the positive feedback loop that leads to persistent airway constriction.

FEATURES OF NITRIC OXIDE METABOLISM AND RISK OF DEVELOPING ENDOTHELIAL DYSFUNCTION IN CHILDREN WITH e-NOS GENE 4a/4b POLYMORPHISM UNDER LONG-TERM ENTERING 137Cs TO BODY. / OSOBLYVOSTI METABOLIZMU OKSYDU AZOTU TA RYZYK ROZVYTKU ENDOTELIAL'NOÏ DYSFUNKTsIÏ U DITEI Z 4a/4b POLIMORFIZMOM GENA eNOS PRY TRYVALOMU NADKhODZhENNI 137Cs DO ORGANIZMU.

OBJECTIVE: To determine the features of the nitrogen oxide metabolism and risk of developing endothelial dysfunc-tion in children with e-NOS 4a/4b gene polymorphism, who live under prolonged enter 137Cs to the body. MATERIALS AND METHODS: There were examined 117 children-residents of radioactively contaminated territories and50 children of control group. The level of stable metabolites was defined in blood serum (NO2- and NO3-). The ther-mographic method was used to register the endothelium dependent reaction of the vascular bed to changes in theblood supply. The ventilation capacity of the lungs was evaluated using this method of pneumotachography.Polymorphism in intron 4 of the gene e-NOS was studied by the method of polymerase chain reaction. The contentof 137Cs in the body of children was determined using a human radiation counter Skrynner M-3. RESULTS AND CONCLUSIONS: In children-residents of radioactively contaminated territories with genotype 4a/4b com-paring to children who had genotype 4b/4b, the decrease in the nitric content of in the blood serum, the increase inthe thermographic index of the recovery period of blood circulation to the baseline level after occlusion test werenoted, that is indicative of the decreased NO-synthase active of vascular endothelium in the carriers of the minorallele a in the 4th intron of gene eNOS (genotype 4a/4b), and is a risk factor for development of endothelial dysfunc-tion. It was proved a decrease in the index of lung tissue elasticity and stretchability - FVC / NFVC of the lungs com-paring to children with genotype 4b/4b, there was a reduction of integral index of respiratory tract permeability -FEV1/NFEV1. The inverse correlation dependence between the presence of allele a in the genotype and the values ofFVC/NFVC of the lungs (r = -0.259; p <0.05) and FEV1/NFEV1 (r = -0.2267; p <0.05) was found. Signs of bron-chospasm were found in the carriers of the allele a in 1.5 times more often than in children-carriers of homozy-gotes from allele b.

Hypocalcaemia in an adult: the importance of not overlooking the cause.

A 58-year-old male patient was admitted at the São Bernardos's Hospital (Setúbal, Portugal) with generalised muscle spasms, dyspnoea, laryngospasm and bronchospasm in the context of severe hypocalcaemia. Despite efforts to correct serum calcium, it remained below average, leading to question the true cause of hypocalcaemia. Low parathyroid hormone and 25-hydroxyvitamin D, along with facial anomalies, palate defect and cognitive impairment with concomitant psychiatric disorder led to a suspicion of a DiGeorge/velocardiofacial/22q11.2 deletion syndrome (DS), which was confirmed through genetic testing. The 22q11.2 DS has a wide phenotypic expression and there are growing reports of diagnosis being made in adulthood. This case report highlights the importance of understanding the cause of refractory hypocalcaemia and alerts medical community to carefully access these patients, for this metabolic disorder may only present in later stages of life.

Inhibition of extracellular nucleotides hydrolysis intensifies the allergic bronchospasm. A novel protective role of ectonucleotidases.

BACKGROUND: Nucleotides released to the extracellular space stimulate purinergic receptors, and their effects are modulated by ectonucleotidases. The role of ATP in the allergic bronchospasm has been scantly studied. METHODS: We used several techniques (plethysmography, organ baths, confocal microscopy, RT-PCR, ATP measurement) to explore the role of nucleotides and ectonucleotidases in the allergic bronchospasm in guinea pigs. RESULTS: While allergenic challenge with a low-dose ovalbumin (OVA) only produced a small bronchospasm (~2-fold the basal lung resistance), previous inhibition of ectonucleotidases by ARL-67156 greatly intensified this response (~11-fold the basal lung resistance, with 44% mortality). Bronchoalveolar lavage fluid obtained during this bronchospasm contained increased ATP concentration. This potentiation was abolished by antagonism of purinergic receptors (suramin+RB2) or TXA2 receptor (SQ29548), or by intratracheal apyrase. In tracheal rings and lung parenchyma strips, OVA caused a concentration-dependent contraction. Suramin+RB2 or levamisole produced a significant rightward displacement of this response, and ARL-67156 did not modify it. Platelets stimulated with OVA released ATP. Confocal images of nonsensitized tracheas showed slight fluorescence for P2Y6 receptors in epithelium and none for P2Y4 . Sensitized animals showed strong fluorescence to both receptors and to alkaline phosphatase in the airway epithelium. This correlated with a large increment in mRNA for P2Y4 and P2Y6 receptors in sensitized animals. CONCLUSIONS: Nucleotides greatly potentiate the allergic bronchospasm when ectonucleotidases activity is diminished, and this effect is probably favored by the upregulation of P2Y4 and P2Y6 receptors in airway epithelium during sensitization. These results prompt for further research on these mechanisms in human asthma.

Role of ß2 adrenoreceptor gene polymorphism in the formation of cold hyperreactivity of the airways in asthmatics.

The relationship between ß(2)-adrenoreceptor gene Arg16Gly polymorphism and bronchial cold reactivity has been studied. Genotype Arg16Arg and allele Arg16 carriership is associated with the development of cold bronchospasm in asthmatics. In addition, a significant reduction of 3,5'-cyclic adenosine monophosphate (cAMP) level has been recorded in Arg16Arg homozygotes on minute 30 after cold provocation in comparison with Gly16Gly genotype carriers. These data indicate the influence of primary dysfunction of ß(2)-adrenoreceptors for the formation of bronchial cold hyperreactivity in the patients. Reduced cAMP synthesis by cells in Arg16Arg carriers indicates congenital liability of their ß(2)-adrenoreceptors to desensitization during cold air isocapnic hyperventilation test.

Crosstalk between Gi and Gq/Gs pathways in airway smooth muscle regulates bronchial contractility and relaxation.

Receptor-mediated airway smooth muscle (ASM) contraction via G(alphaq), and relaxation via G(alphas), underlie the bronchospastic features of asthma and its treatment. Asthma models show increased ASM G(alphai) expression, considered the basis for the proasthmatic phenotypes of enhanced bronchial hyperreactivity to contraction mediated by M(3)-muscarinic receptors and diminished relaxation mediated by beta(2)-adrenergic receptors (beta(2)ARs). A causal effect between G(i) expression and phenotype has not been established, nor have mechanisms whereby G(i) modulates G(q)/G(s) signaling. To delineate isolated effects of altered G(i), transgenic mice were generated overexpressing G(alphai2) or a G(alphai2) peptide inhibitor in ASM. Unexpectedly, G(alphai2) overexpression decreased contractility to methacholine, while G(alphai2) inhibition enhanced contraction. These opposite phenotypes resulted from different crosstalk loci within the G(q) signaling network: decreased phospholipase C and increased PKCalpha, respectively. G(alphai2) overexpression decreased beta(2)AR-mediated airway relaxation, while G(alphai2) inhibition increased this response, consistent with physiologically relevant coupling of this receptor to both G(s) and G(i). IL-13 transgenic mice (a model of asthma), which developed increased ASM G(alphai), displayed marked increases in airway hyperresponsiveness when G(alphai) function was inhibited. Increased G(alphai) in asthma is therefore a double-edged sword: a compensatory event mitigating against bronchial hyperreactivity, but a mechanism that evokes beta-agonist resistance. By selective intervention within these multipronged signaling modules, advantageous G(s)/G(q) activities could provide new asthma therapies.

El asma en los primeros años de la vida y su relación con las infecciones virales / No disponible

El mayor riesgo para la aparición de episodios de broncoespasmo en lactantes y niños pequeños proviene de las infecciones por virus respiratorios. Los virus más frecuentemente responsables de broncoespasmo en este grupo de edad son el virus sincitial respiratorio (RSV) y el metapneumovirus humano. En niños en edad escolar y adolescentes el papel predominante es de los rinovirus. La bronquiolitis (BQL) por VRS es causa de hospitalización del 1-2% de los menores de 2 años en cada temporada de otoño-invierno. Su expresión clínica es muy diferente y probablemente depende de factores genéticos y de la respuesta neuroinmune del niño afectado. La BQL clínicamente relevante se asocia con bronquitis sibilante y asma durante los años siguientes. En la BQL y el broncoespasmo recurrente posterior se ha demostrado aumento de producción de leucotrienos. Moléculas que impidan su liberación o neutralicen sus efectos serán beneficiosas en el asma posterior a la BQL, desencadenada mayoritariamente por virus. En el manejo del asma inducida por virus en lactantes y preescolares, los corticosteroides inhalados han demostrado eficacia limitada al período del tratamiento activo, no exenta totalmente de repercusión en el crecimiento del niño. La idea de poder modificar el curso natural de la enfermedad con la instauración precoz de los esteroides inhalados no ha sido confirmada en los estudios actualmente disponibles. El montelukast, fármaco antagonista de receptores de leucotrienos, ha demostrado un control parcial de los síntomas que frecuentemente persisten después de la BQL por VRS. El empleo de este fármaco en el broncoespasmo recurrente de lactantes y preescolares ha demostrado beneficios clínicamente relevantes sin efectos adversos destacables. La vacunación antigripal en niños de riesgo y un buen control de la enfermedad asmática son estrategias recomendables con el objetivo de afrontar en mejores condiciones las temporadas de invierno en las que las infecciones respiratorias originan numerosas exacerbaciones asmáticas agudas. Nuestro entendimiento de éstas es incompleto y difícil de aprehender, dadas las dificultades de comprensión de las interacciones entre los diferentes agentes desencadenantes (virus, alérgenos, contaminantes, clima) pero ahondar en él proporcionará oportunidades para la intervención terapéutica (AU)

The biggest risk for the appearance of episodes of wheezing in infants and children comes from the infections by respiratory viruses. The viruses most frequently responsible of wheezing in this group are the respiratory syncytial virus (RSV) and the human metapneumovirus. In school aged children and teenagers the rhinoviruses have the main role. The bronchiolitis (BQL) by RSV is cause of hospitalization in 1-2% of children younger than two in each autumn and winter season. Its clinical expression is very different and probably related with genetic factors and the neurological and immune response in mucosal airway of the affected kid. The BQL clinically important is associated with wheezing and asthma during the following years. In the BQL and later recurrent wheezing an incremented production of leukotrienes has been demonstrated. Molecules able to avoid its liberation or to neutralise its effects can have good effects in the asthma after the bronchiolitis, started most of the time by viruses. In the handling of the asthma leaded by viruses in infants and preschoolers, inhaled corticosteroids have demonstrated effectiveness limited to the active course period, but they can have some repercussions in the growth of the affected kid. The idea of being able to modify the natural course of the illness with the early establishment of breathed steroids has not been confirmed with the studies now available. Montelukast, a receptor antagonist of leukotrienes, has demonstrated a partial control of the symptoms that frequently remain after the bronchiolitis by RSV. The use of this medicine in the recurrent wheezing in infants and preschoolers has demonstrated clinical benefits without any significant adverse effects. Influenza immunization in children at risk and a good control of the asthmatic illness are good strategies, with the aim of facing better conditions in the winter season when respiratory infections origin numerous acute asthmatic exacerbations. Our knowledge of asthma relapses is incomplete, because of the difficulties to understand the interactions between the different starting agents (viruses, allergens, pollution, weather) but to deepen in it will give chances for the therapeutic intervention (AU)

Lyn-deficient mice develop severe, persistent asthma: Lyn is a critical negative regulator of Th2 immunity.

The etiology of asthma, a chronic inflammatory disorder of the airways, remains obscure, although T cells appear to be central disease mediators. Lyn tyrosine kinase has been implicated as both a facilitator and inhibitor of signaling pathways that play a role in allergic inflammation, although its role in asthma is unclear because Lyn is not expressed in T cells. We show in the present study that Lyn-/- mice develop a severe, persistent inflammatory asthma-like syndrome with lung eosinophilia, mast cell hyperdegranulation, intensified bronchospasm, hyper IgE, and Th2-polarizing dendritic cells. Dendritic cells from Lyn-/- mice have a more immature phenotype, exhibit defective inhibitory signaling pathways, produce less IL-12, and can transfer disease when adoptively transferred into wild-type recipients. Our results show that Lyn regulates the intensity and duration of multiple asthmatic traits and indicate that Lyn is an important negative regulator of Th2 immune responses.

Malformaciones adenomatoidea quística congénita en un niño escolar / Cystic adenomatoid malformations in scholar boy

La malformación adenomatoidea congénita (MAQC) es una anomalia producida por alteraciones de los bronquios terminales. En la histologia se aprecian zonas adenomatosas cerradas y zonas quísticas dilatadas. En los recien nacidos existe una dificultad respiratoria progresiva, lo que no ocurre en pacientes mayores de un año donde se aprecian infecciones respiratorias recurrentes. El diagnóstico antenatal es ideal y I.R.M. se constituye como e método más efectivo del mismo, La radiografia, el ultrasonido y la T.A.C. continuan siendo armas importantes en el diagnóstico. El tratamiento siempre es quirurgico con la resección del parénquima afectado. Se describe a un paciente de 5 años 11 meses de edad, con introducción temprana de alimentos alergénicos, abuelo paterno asmático, abuela y tia paternas alérgicas, ambos padres con rinitis alérgica y asma. Desde los 3 años el niño presenta cuadros de broncoespasmo de predominio nocturno. a los 4 años sufre traumatismo torácico derecho con neumotórax y hemotórax que requiere colocación de sello de agua, posterior a lo cual muestra incremento del broncoespasmo y de infecciones recurrentes de vias aéres superiores e inferiores. A los 5 años acude a consulta especializada y se sospecha de malformaciones congénitas, en las radiografías se aprecian zonas quisticas apicales izquierdas que comprimen el parénquima basal, estos hallazgos se confirman con T.A.C y Gammagrafia. Se realiza tratamiento con cromoglicato y resección del lóbulo superior izquierdo. El examen patológico de la pieza operatoria confirma el diagnóstico de Malformacion adenomatoidea quística congénita tipo II.(au)

Atopy in infancy predicts the severity of bronchial hyperresponsiveness in later childhood.

We have prospectively followed 52 children of atopic parents from birth to age 7 years, documenting clinical atopic disease and allergen skin test reactions. We found bronchial hyperresponsiveness (BHR) to histamine in 13 (25%) of the children at 7 years of age with 25 (48%) being atopic on skin testing and 15 (29%) having current wheeze, whereas 30 children (58%) had wheezed at some time during this period. BHR was significantly associated with wheeze and atopy at 5 and 7 years of age, but not during infancy. The six children with moderate to severe BHR (provocative dose causing a 20% fall in FEV1 less than 0.8 mumol) formed a distinct subgroup with significantly more wheeze and atopy both during infancy and at 5 years of age when these children were compared to children with milder degrees of BHR. The group with moderate to severe BHR also differed significantly from the nonhistamine-reactive group, whereas children with milder degrees of BHR were not significantly different. We conclude that subjects most likely to develop the more severe degrees of BHR during later childhood are children who manifest atopy in infancy.

Genetic factors in non-specific bronchial reactivity in rats.

Two bronchoconstrictory agents, serotonin (5 HT) and carbachol, were investigated in different inbred rat strains in order to delineate possible factors influencing the bronchial reactivity. The challenge was given intravenously and a single dose was given to an individual animal. Inbred strains of rats differed significantly from each other in their reactivity to 5 HT and to carbachol. IC rats were good reactors to both 5 HT and carbachol. RA rats were intermediate reactors to both agents. OM/N rats had a good reaction to 5 HT, but showed only a minor bronchoconstriction after carbachol. BN and LE rats were poor reactors to both agents. The strain reactivities to the 2 provocation agents were not related. Breeding studies, using a good reactor, IC, and a poor reactor, DA strain, showed that the bronchial reactivity to 5 HT was inherited with a pattern that fitted with the autosomal recessive way of inheritance, high reactivity being recessive.