Causas de Morte em Doentes com Hemofilia: Estudo Retrospectivo de 1979 a 2007, no Serviço de Imunohemoterapia do HSJ

Neurokinin A (NKA) induces bronchoconstriction mediated by tachykinin NK2 receptors in animals and humans, and may be increased in asthma. Because beta(2)-adrenoceptor agonists are the most widely used bronchodilators in asthma, we investigated the effects of the beta(2)-adrenoceptor agonist fenoterol on NK2 receptor messenger RNA (mRNA) and receptor density as well as the functional responses of bovine tracheal smooth muscle to the NK2 receptor agonist [beta-Ala(8)]-NKA(4-10) in vitro, using Northern blot analysis, receptor binding, and organ bath studies. Incubation with fenoterol induced a time- and concentration-dependent upregulation of NK2 receptor mRNA (71% increase after 12 h at 10(-7) M fenoterol), which was abolished by propranolol (a nonselective beta-adrenoceptor agonist) and ICI118551 (a selective beta(2)-adrenoceptor antagonist), but not by CGP20712A (a selective beta(1)-adrenoceptor antagonist), indicating that fenoterol acts via beta(2)-adrenoceptors. These effects were mimicked by forskolin and prostaglandin E-2 (PGE,), both agents that increase cyclic adenosine monophosphate (cAMP), and by the cAMP analogue 8-bromo-cAMP. The upregulation was blocked by cycloheximide, indicating that it requires new protein synthesis, and was accompanied by an increase in both the stability of NK2 receptor mRNA and the rate of NK2 receptor gene transcription. Radioligand binding assay using the selective NK2 receptor antagonist [H-3]SR48968 showed a significant increase in the number of receptor binding sites after 12 h and 18 h, which was accompanied by an increased contractile responsiveness to the NK2 receptor agonist [beta-Ala(8)]-NKA(4-10). Dexamethasone completely prevented the fenoterol-induced increase in NK2 receptor mRNA and in the contractile response. We conclude that beta(2)-adrenoceptor agonists induce upregulation of functional NK2 receptors in airway smooth muscle by increasing cAMP, and that this can be prevented by a corticosteroid. The increased responsiveness could be relevant to asthma control and mortality

The neuropeptide NMU amplifies ILC2-driven allergic lung inflammation

Type 2 innate lymphoid cells (ILC2s) both contribute to mucosal homeostasis and initiate pathologic inflammation in allergic asthma. However, the signals that direct ILC2s to promote homeostasis versus inflammation are unclear. To identify such molecular cues, we profiled mouse lung-resident ILCs using single-cell RNA sequencing at steady state and after in vivo stimulation with the alarmin cytokines IL-25 and IL-33. ILC2s were transcriptionally heterogeneous after activation, with subpopulations distinguished by expression of proliferative, homeostatic and effector genes. The neuropeptide receptor Nmur1 was preferentially expressed by ILC2s at steady state and after IL-25 stimulation. Neuromedin U (NMU), the ligand of NMUR1, activated ILC2s in vitro, and in vivo co-administration of NMU with IL-25 strongly amplified allergic inflammation. Loss of NMU-NMUR1 signalling reduced ILC2 frequency and effector function, and altered transcriptional programs following allergen challenge in vivo. Thus, NMUR1 signalling promotes inflammatory ILC2 responses, highlighting the importance of neuro-immune crosstalk in allergic inflammation at mucosal surfaces

fMRI scanner noise interaction with affective neural processes

The purpose of the present study was the investigation of interaction effects between functional MRI scanner noise and affective neural processes. Stimuli comprised of psychoacoustically balanced musical pieces, expressing three different emotions (fear, neutral, joy). Participants (N=34, 19 female) were split into two groups, one subjected to continuous scanning and another subjected to sparse temporal scanning that features decreased scanner noise. Tests for interaction effects between scanning group (sparse/quieter vs continuous/noisier) and emotion (fear, neutral, joy) were performed. Results revealed interactions between the affective expression of stimuli and scanning group localized in bilateral auditory cortex, insula and visual cortex (calcarine sulcus). Post-hoc comparisons revealed that during sparse scanning, but not during continuous scanning, BOLD signals were significantly stronger for joy than for fear, as well as stronger for fear than for neutral in bilateral auditory cortex. During continuous scanning, but not during sparse scanning, BOLD signals were significantly stronger for joy than for neutral in the left auditory cortex and for joy than for fear in the calcarine sulcus. To the authors' knowledge, this is the first study to show a statistical interaction effect between scanner noise and affective processes and extends evidence suggesting scanner noise to be an important factor in functional MRI research that can affect and distort affective brain processes

Glucocorticoids reduce tachykinin NK2 receptor expression in bovine tracheal smooth muscle

Neurokinin A is not only a potent bronchoconstrictor, but also has immuno-modulatory effects in animals and man, mediated via tachykinin NK2 receptors. We have examined the effect of the glucocorticoid, dexamethasone, on tachykinin NK2 receptor mRNA and the number of tachykinin NK2 receptors in bovine tracheal smooth muscle in vitro by Northern blot analysis using a human tachykinin NK2 receptor cDNA probe and receptor binding assay using [3H]SR48968 {(S)-N-methyl-N[4-acetylamino-4-phenylpiperidino-2-(3,4-dichlorophenyl) butyl]benzamide}. Tachykinin NK2 receptor mRNA showed a time-dependent suppression (62% reduction after 6 h at 10-7 M of dexamethasone), as well as a concentration-dependent suppression after the incubation with dexamethasone (IC50 = 1.3 x 10-8 M). This suppression was abolished by the glucocorticoid receptor antagonist, mifepristone (RU38486), indicating that dexamethasone acts via the glucocorticoid receptor. It was also abolished by the protein synthesis inhibitor, cycloheximide (10 μg/ml), indicating that new protein synthesis is required on this suppression. Using the RNA polymerase inhibitor actinomycin D (5 μg/ml), we showed that the stability of tachykinin NK2 receptor mRNA was not affected by dexamethasone (t( 1/4 ) = 5 h). Nuclear run-on assays revealed a 51% reduction in the rate of tachykinin NK2 receptor gene transcription after treatment with dexamethasone for 6 h. Radioligand binding assay using an selective tachykinin NK2 receptor antagonist, [3H]SR48968 showed a significant decrease in the number of receptor binding sites after 16 h (B(max) = 262 ± 23 versus 213 ± 13 fmol/mg protein for vehicle and dexamethasone treatment respectively, P < 0.05), with no significant change at the earlier time points. These results suggest that glucocorticoids act on glucocorticoid receptors to decrease tachykinin NK2 receptor expression by decreasing the rate of tachykinin NK2 receptor gene transcription.link_to_subscribed_fulltex

β-Adrenergic agonists and bronchial hyperreactivity: Role of β2- adrenergic and tachykinin neurokinin-2 receptors

Background: β2-Adrenergic agonists are the most widely used bronchodilators for the treatment of asthma. On the other hand, there is concern that excessive use of β2-agonists may contribute to the exacerbation of asthma. However, the mechanism of such adverse effects of β2-agonists is not completely clear. Objective: The aim of this study was to assess the direct influence of β2-agonists on airways by analyzing the effect of a β2-agonist, fenoterol, on airway sensitivity in an animal model and on tachykinin neurokinin-2 receptor expression in bovine tracheal smooth muscle. Methods: We performed an acetylcholine challenge test on ovalbumin sensitized guinea pigs that were exposed to daily inhalation of ovalbumin and fenoterol. We also investigated the effects of fenoterol on neurokinin-2 receptor messenger RNA and density with Northern blot analysis and receptor binding assay. Result: The increase of airway responsiveness and the decrease of β2-adrenergic receptors were found in guinea pigs that were treated with fenoterol. There were time- and dose-dependent increases of neurokinin-2 receptor mRNA and of density in tracheal smooth muscle that was treated with fenoterol. Conclusion: This increased airway responsiveness, increased neurokinin-2 receptor expression, and decreased β2-adrenergic receptor density may be relevant to asthma exacerbation.link_to_subscribed_fulltex

Up-regulation of airway smooth muscle histamine H1 receptor mRNA, protein, and function by β2-adrenoceptor activation

Histamine, released from activated mast cells, causes bronchoconstriction mediated by H1 receptors, whereas β2-agonists are widely used for the relief of bronchoconstriction. In this study, we examined the effects of the β2-adrenoceptor agonist, fenoterol, on the expression of H1 receptors at the mRNA and protein levels, and functional responses, incubation of bovine tracheal smooth muscle with fenoterol (10-7 M) for 2 h increased H1 receptor mRNA (maximum ~190%). The number of H1 receptors was increased after 12 and 18 h without any change in binding affinity. In the contraction experiments, the concentration-response curves for histamine- induced contraction were shifted significantly to the left after 18-h exposure to fenoterol, consistent with the increase in receptor number. The fenoterol-induced increase in H1 receptor mRNA was concentration-dependent and was abolished by propranolol and ICI 118551, but not by CGP 20712A, indicating that fenoterol acts via β2-adrenoceptors. These effects were mimicked by other cAMP-elevating agents forskolin and prostaglandin E2, and by the stable cAMP analog 8-bromo-cAMP. Cycloheximide alone produced superinduction of H1 receptor mRNA and augmented the fenoterol-induced increase in H1 receptor mRNA. Fenoterol increased both the stability and the transcription rate of H1 receptor mRNA. Pretreatment with dexamethasone did not prevent fenoterol-induced up-regulation of H1 receptor mRNA. Thus, fenoterol increases the expression of airway smooth muscle H1 receptors via activation of the cAMP system through increased gene transcription and mRNA stability. This mechanism may be involved in the adverse responses encountered with the clinical use of short-acting β2-agonists.link_to_subscribed_fulltex