Airway Neurogenic Inflammation Research Articles

Effects of Angelicae Sinensis Radix on cAMP/Epac signaling pathway in the treatment of chronically infected cough mice with Yin deficiency syndrome

To investigate the effects of Angelicae Sinensis Radix (ASR) on cyclic adenosine monophosphate (cAMP) /exchange protein activated by cAMP (Epac) signaling pathway in the treatment of chronically infected cough mice with Yin deficiency syndrome. Mice were randomly divided into blank control group, model control group, positive control group and ASR group (n=8). The chronic cough mouse model of hyperreactive and infected airway with Yin deficiency syndrome was established with fumigation (once a day, 30 days in total), lipopolysaccharide nasal drip (every 3 days 10 μl, 10 times in total), intragastric administration of thyroid gland (120 mg/kg, once a day, a total of 15 days) and inhalation of ammonia (3 min / time × 10 times). On the basis of observing eating and drinking water, body weight and autonomic activities, the effects of ASR on metabolic level, autonomous activities, antitussive effect, cell factor in bronchoalveolar lavage fluid (BALF) brain tissue 5-HT and lung tissue related active factors(SP, PGP9.5, cAMP, Epac1) were detected. ASR could significantly restrain cough, alleviate the pathological changes of bronchioles, reduce the contents of IL-4, IL-13, TNF-α in BALF and the levels of SP, PGP9.5, cAMP and Epac1 in lung tissues, increase the content of 5-HT in brain tissue (P＜0.05, 0.01). ASR has some effects on restraining cough and one of its mechanisms is to down-regulate cAMP/Epac signaling pathway, to alleviate airway neurogenic inflammation and reduce sensitivity of cough neural pathway.

Cough hypersensitivity in patients with metabolic syndrome: a clinical finding and its possible mechanisms

PurposeTo investigate the changes of cough sensitivity in patients with metabolic syndrome and its possible mechanisms.MethodA total of 29 metabolic syndrome (MetS) patients with OSAHS (group-1), 22 MetS patients without OSAHS (group-2), and 25 healthy controls (group-3) were included. All participants underwent a routine physical examination and completed the gastroesophageal reflux disease questionnaire (GerdQ), and the inflammatory mediator profile were determined. The cough threshold for capsaicin, induced sputum cell count and cell classification, and inflammatory mediators in induced sputum supernatants were compared. The correlation between capsaicin cough sensitivity and various indicators in the MetS population was analyzed.ResultsThe minimum concentration of inhaled capsaicin needed to induce ≥ 5 coughs (C5) was significantly different among three groups (H = 14.393, P = 0.001) and lower for group-1 and group-2 than it for group-3 (P = 0.002, P = 0.005). The percentage of neutrophils in induced sputum and the concentrations of calcitonin gene-related peptide (CGRP), substance P (SP), and interleukin 8 (IL-8) in the sputum supernatant of group-1 and group-2 were significantly higher than those of group-3. Besides, the pepsin concentrations were significantly different among the 3 groups (F = 129.362, P < 0.001), which significantly was highest in group-1 (P < 0.001) and lowest in group-3 (P < 0.001). Triglycerides, AHI, pepsin concentration and BMI were risk factors of increased capsaicin cough sensitivity.ConclusionIncreased capsaicin cough sensitivity in MetS patients is closely related to sleep apnea and gastroesophageal reflux. For patients in MetS patients without OSAHS, gastroesophageal reflux is an important factor for increased capsaicin cough sensitivity. Airway inflammation, especially airway neurogenic inflammation, may also play a role in the pathogenesis of increased capsaicin cough sensitivity.Trial registration The protocol was registered in the Chinese Clinical Trials Register (http://www.chictr.org.cn/) (ChiCTR1800014768). Written informed consent was obtained from all participants before enrollment.

Efficacy of active compounds of Chanqin granules on airway neurogenic inflammation induced by PM2.5 in vivo.

To investigate the efficacy of active compounds of Chanqin (CQ) granules on PM2.5-induced airway neurogenic inflammation in vivo, and to elucidate the underlying mechanisms of action. The Traditional Chinese Medicine systems pharmacology (TCMSP) database was searched, and the results were combined with oral bioavailability and drug analysis to identify the compounds in CQ granules. The pharmacophore modeling approach was used to predict the compound targets, and the diseases corresponding to the targets were obtained by searching the therapeutic target database (TTD), pharmacogenomics knowledgebase (PharmGKB) and DrugBank databases. Cytoscape software was used to construct the network pharmacological charts for Component-Target and Target-Disease interactions of the CQ granules. Then, the mechanisms of action and effectiveness of CQ granules for the treatment of PM2.5-induced airway neurogenic inflammation were analyzed. A total of 195 compounds and 171 targets were obtained from the analyses. A total of 569 corresponding diseases were identified for these targets. Component-target and target-disease networks were constructed. The possible mechanisms and effective components in CQ granules for treating airway neurogenic inflammation were analyzed. Quercetin, kaempferol and isorhamnetin, beta-sitosterol and sitosterol, which are typically found in the formulation, have extensive pharmacological activities, including anti-inflammatory, antioxidant and antiviral actions and neuroprotective properties. Among these targets, androgen receptor, estrogen receptor, prostaglandin G/H synthase 2, and inducible nitric oxide synthase play important pathological roles, including the induction of neurogenic inflammation. CQ granules may have therapeutic effectiveness for numerous diseases in addition to respiratory diseases, including neoplasms, digestive system diseases, cardiovascular diseases, respiratory tract diseases and nervous system diseases. In vivo, CQ granules are effective in treating pulmonary inflammation and downregulate neuropeptides in the bronchoalveolar lavage fluid after PM2.5 exposure. CQ granules significantly decreased the levels of neurokinin A, neurokinin B and calcitonin gene-related peptide in the lung and dorsal root ganglia. CQ also significantly suppressed the upregulation of p-extracellular regulated protein kinase 1/2 and p-methyl ethyl ketone 1/2 induced by PM2.5 exposure. CQ granules have potential for the treatment of neurogenic inflammation induced by PM2.5 in vivo, and the mechanism might involve downregulation of neuropeptides in the BALF, lung and dorsal root ganglia.

Mycobacterium vaccae nebulization protects Balb/c mice against bronchial asthma through neural mechanisms

Objectives Bronchial asthma can be effectively controlled but not be cured, its etiology and pathogenesis are still unclear, and there are no effective preventive measures. The key characteristic of asthma is chronic airway inflammation, and recent research has found that airway neurogenic inflammation plays an important role in asthma. We previously found that Mycobacterium vaccae nebulization protects against asthma. Therefore, this objective of this study is to explore the effect of M. vaccae nebulization on asthmatic neural mechanisms. Methods A total 18 of female Balb/c mice were randomized into normal, asthma control, and M. vaccae nebulization (Neb.group) groups, and mice in the Neb.group were nebulized with M. vaccae one month before the asthmatic model was established. Then, 1 month later, the mice were sensitized and challenged with ovalbumin. Twenty-four hours after the last challenge, mouse airway responsiveness; pulmonary brain-derived neurotropic factor (BDNF), neurofilament-medium length (NF-M, using NF09 antibody), and acetylcholine expression; and nerve growth factor (NGF) mRNA level were determined. Results We found that the BDNF, NF09, acetylcholine expression, and NGF mRNA level were decreased in the Neb.group compared with levels in the asthma control group. Conclusion M. vaccae nebulization may protected in Balb/c mice against bronchial asthma through neural mechanisms.

Dorsal Vagal Complex Modulates Neurogenic Airway Inflammation in a Guinea Pig Model With Esophageal Perfusion of HCl.

Neurogenic airway inflammation in chronic cough and bronchial asthma related to gastroesophageal reflux (GER) is involved in the esophageal–bronchial reflex, but it is unclear whether this reflex is mediated by central neurons. This study aimed to investigate the regulatory effects of the dorsal vagal complex (DVC) on airway inflammation induced by the esophageal perfusion of hydrochloric acid (HCl) following the microinjection of nuclei in the DVC in guinea pigs. Airway inflammation was evaluated by measuring the extravasation of Evans blue dye (EBD) and substance P (SP) expression in the airway. Neuronal activity was indicated by Fos expression in the DVC. The neural pathways from the lower esophagus to the DVC and the DVC to the airway were identified using DiI tracing and pseudorabies virus Bartha (PRV-Bartha) retrograde tracing, respectively. HCl perfusion significantly increased plasma extravasation, SP expression in the trachea, and the expression of SP and Fos in the medulla oblongata nuclei, including the nucleus of the solitary tract (NTS) and the dorsal motor nucleus of the vagus (DMV). The microinjection of glutamic acid (Glu) or exogenous SP to enhance neuronal activity in the DVC significantly potentiated plasma extravasation and SP release induced by intra-esophageal perfusion. The microinjection of γ-aminobutyric acid (GABA), lidocaine to inhibit neuronal activity or anti-SP serum in the DVC alleviated plasma extravasation and SP release. In conclusion, airway inflammation induced by the esophageal perfusion of HCl is regulated by DVC. This study provides new insight for the mechanism of airway neurogenic inflammation related to GER.

Vagotomy decreases the neuronal activities of medulla oblongata and alleviates neurogenic inflammation of airways induced by repeated intra-esophageal instillation of HCl in guinea pigs.

Neuronal activity in the medulla oblongata and neurogenic inflammation of airways were investigated in a guinea pig model induced by repeated intra-esophageal instillation of hydrochloric acid (HCl) after vagotomy. Unilateral vagotomy was performed in the vagotomy group, while a sham-operation was performed in the sham group. Operation was not conducted in sham control group. Airway inflammation was observed with hematoxylin and eosin (HE) staining. C-fos protein was measured by immunohistochemistry (IHC) and Western blot (WB). Substance P was examined by IHC and enzyme-linked immuno sorbent assay (ELISA). Airway microvascular permeability was detected by evans blue dye (EBD) fluorescence. Inflammation of airway was observed in the trachea and bronchi after chronic HCl perfusion into the lower esophagus, and was alleviated after unilateral vagotomy. C-fos expression in the medulla oblongata was lower in the vagotomy group compared to the sham control and sham groups. Substance P-like immunoreactivity (SP-li), concentration and microvascular leakage in airway were lower in the vagotomy group than that in the other groups. Our results suggest that vagotomy improved neurogenic inflammation of airways and decreased neuronal activities, the afferent nerves and neurons in medulla oblongata may be involved in neurogenic inflammation of airways mediated by esophageal-bronchial reflex.

TRP functions in the broncho-pulmonary system

The current understanding of the role of transient receptor potential (TRP) channels in the airways and lung was initially based on the localization of a series of such channels in a subset of sensory nerve fibers of the respiratory tract. Soon after, TRP channel expression and function have been identified in respiratory nonneuronal cells. In these two locations, TRPs regulate physiological processes aimed at integrating different stimuli to maintain homeostasis and to react to harmful agents and tissue injury by building up inflammatory responses and repair processes. There is no doubt that TRPs localized in the sensory network contribute to airway neurogenic inflammation, and emerging evidence underlines the role of nonneuronal TRPs in orchestrating inflammation and repair in the respiratory tract. However, recent basic and clinical studies have offered clues regarding the contribution of neuronal and nonneuronal TRPs in the mechanism of asthma, chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, cough, and other respiratory diseases.

Regulation of Neurogenic Airway Inflammation via the Dorsal Vagal Complex in a Guinea Pig Model of Gastroesophageal Reflux

SESSION TITLE: Asthma III SESSION TYPE: Original Investigation Poster PRESENTED ON: Saturday, April 16, 2016 at 11:45 AM - 12:45 PM PURPOSE: The aim of the study was to investigate regulation of neurogenic airway inflammation via the dorsal vagal complex (DVC). METHODS: Neuronal activity in the DVC and transmitter expression as well as its effects on regulation of airway inflammation were observed in a guinea pig model of GER. The effects of DVC on SP expression and microvascular leakage of airway were measured using a stereotaxic technique combined with microinjection to change the activities of neurons or SP concentration in the target area. The pseudorabies virus Bartha (PRV Bartha) was used as a retrograde tracer to examine the pathway from DVC to airway. RESULTS: Chronic hydrochloric acid (HCl) perfusion into the lower esophagus induced plasm leakage and neuropeptide release in lung. SP and Fos expressions were increased in the nucleus of the solitary tract (nTS) and dorsal motor nucleus of the vagus (DMV). SP expression and microvascular leakage in the airway changed in accordance with neuronal excitability or the SP concentration in the DVC. PRV-infected neurons were distributed in the nTS and the DMV, and about 40% of these were positive for SP. CONCLUSIONS: CNS is involved in the esophageal-bronchial reflex and neurogenic airway inflammation can be regulated by DVC, which provide a new insight for the treatment of refractory cough and severe asthma. CLINICAL IMPLICATIONS: The airway neurogenic inflammation may be regulated by DVC, which provides a new therapeutic target in the pathway from airway to CNS, especially refractory cough and severe asthma DISCLOSURE: The following authors have nothing to disclose: Zhe Chen, Le-jia Sun, Hui Chen, Da-chuan Gu, Wei-tao Zhang, Rong Dong, KeFang Lai No Product/Research Disclosure Information

Effect of transient receptor potential vanilloid-1 on cough hypersensitivity induced by particulate matter 2.5

AimsThe mechanism of cough hypersensitivity induced by particulate matter 2.5 (PM2.5) remains elusive. The current study was designed to explore the effect of transient receptor potential vanilloid-1 (TRPV1) on cough hypersensitivity in airway and central nervous system. Main methodsThe PM2.5-induced chronic cough model of guinea pig was established by exposure to different doses of PM2.5 for three weeks. After exposure, the animals were microinjected with TRPV1 agonist capsaicine, antagonist capsazepine in the dorsal vagal complex respectively. Cough sensitivity was measured by determining the provocative concentration of citric acid inducing 5 or more coughs (C5). Airway inflammation was detected by hematoxylin eosin (HE) staining and Evans blue fluorescence, and substance P (SP) and TRPV1 expressions in airway were observed by immunohistochemical staining. TRPV1 expressions in the dorsal vagal complex were observed by immunofluorescence. Retrograde tracing by pseudorabies virus-Bartha (PRV-Bartha) was conducted to confirm the regulatory pathway between airway and central nervous system. Key findingsPM2.5 induced TRPV1 expressions in both of airway and dorsal vagal complex and airway neurogenic inflammation. Airway vascular permeability increased after being exposed to PM2.5. The expressions of SP in the airway and airway inflammation was increased after microinjecting TRPV1 agonist, and decreased after microinjecting TRPV1 antagonist. PRV infected neurons in medulla oblongata mainly located in the dorsal vagal complex. SignificanceThese findings show that TRPV1 in the dorsal vagal complex could promote airway neurogenic inflammation and cough reflex sensitivity through neural pathways of vagal complex-airways, which indicate the therapeutic potential of specific inhibition of TRPV1 for chronic cough induced by PM2.5.

Chronic neurokinin-1 receptor antagonism fails to ameliorate clinical signs, airway hyper-responsiveness or airway eosinophilia in an experimental model of feline asthma.

Feline allergic asthma is a common chronic lower airway disease characterized by clinical signs attributed to eosinophilic inflammation, airway hyper-responsiveness (AHR) and airway remodeling. Tachykinins released from sensory nerves and immune cells bind neurokinin-1 (NK-1) receptors in the lung. The resultant neurogenic airway inflammation has been implicated in asthma pathogenesis. In mouse models and spontaneous human asthma, NK receptor antagonists reduce bronchospasm and inflammation. We hypothesized that chronic administration of maropitant, an NK-1 receptor antagonist, would decrease clinical signs of asthma, AHR and eosinophilic inflammation in experimentally asthmatic cats. Cats (n = 6) induced to have asthma using Bermuda grass allergen (BGA) were enrolled in a randomized, prospective, placebo-controlled crossover design study. Cats received either oral maropitant (2 mg/kg) or placebo q48h for 4 weeks; following a 2 week washout, cats were crossed-over to the alternate treatment. Study endpoints included subjective clinical scoring systems after BGA challenge, ventilator-acquired pulmonary mechanics to assess AHR after bronchoprovocation with methacholine, and collection of bronchoalveolar lavage fluid to quantify airway eosinophilia. Statistical analysis was performed using a Mann-Whitney rank sum test with P <0.05 considered significant. Administration of maropitant for 1 month in experimentally asthmatic cats produced no significant difference in clinical scoring scheme (P = 0.589 and P = 1.0), AHR (P = 0.818) or airway eosinophilia (P = 0.669) compared with placebo. Chronic administration of maropitant was ineffective at blunting clinical signs, AHR and airway eosinophilia in experimental feline asthma and thus cannot be recommended as a novel treatment for this disorder.

Exploratory study comparing dysautonomia between asthmatic and non-asthmatic elite swimmers

BackgroundDysautonomia has been independently associated with training and exercise-induced bronchoconstriction. In addition, neurogenic airway inflammation was recently associated with swimmers-asthma. We aimed to assess the relation between autonomic nervous system and airway responsiveness of asthmatic elite swimmers. MethodsTwenty-seven elite swimmers, 11 of whom had asthma, were enrolled in this exploratory cross-sectional study. All performed spirometry with bronchodilation, skin prick tests and methacholine challenge according to the guidelines. Pupillometry was performed using PLR-200™ Pupillometer. One pupil light response curve for each eye was recorded and the mean values of pupil's maximal and minimal diameters, percentage of constriction, average and maximum constriction velocities (parasympathetic parameters), dilation velocity, and total time to recover 75% of the initial size (sympathetic parameters) were used for analysis. Asthma was defined using IOC-MC criteria; subjects were divided into airway hyperesponsiveness (AHR) severity according to methacholine PD20 in: no AHR, borderline, mild, moderate and severe AHR. Differences for pupillary parameters between groups and after categorization by AHR severity were assessed using SPSS 20.0 (p≤0.05). In individuals with clinically relevant AHR, correlation between PD20 and pupillary parameters was investigated with Spearman's correlation test. ResultsNo statistically significant differences were observed between asthmatic and non-asthmatic swimmers regarding parasympathetic parameters. When stratified by AHR, maximal and minimal diameters and percentage of constriction were significantly lower among those with severe AHR. Among swimmers with clinically relevant AHR (n=18), PD20 correlated with parasympathetic activity: maximal (r=0.67, p=0.002) and minimal diameters (r=0.75, p<0.001), percentage of constriction (r=−0.59, p=0.011) and latency (r=0.490, p=0.039). ConclusionsNo significant differences were observed between asthmatic and non-asthmatic swimmers regarding parasympathetic parameters, but among those with relevant AHR an association was found. Although limited by the sample size, these findings support the relation between dysautonomia and AHR in asthmatic swimmers.

Val66Met polymorphism in the BDNF gene in children with bronchial asthma.

Bronchial asthma is a chronic respiratory disease characterized by airway inflammation. There is increasing evidence that neurotrophins play an important role in the development and maintenance of neurogenic airway inflammation in chronic allergic diseases. Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin family and has several important functions in the airways. There are only a few reports on the association between genetic variations in the BDNF gene and various allergic diseases, and the results are generally conflicting. Therefore, we aimed to study the functional polymorphism Val66Met (also called rs6265 or G196A) in the BDNF gene in a group of asthmatic children and healthy controls. We studied 248 asthmatic patients (aged 12.28 ± 0.24 years) and 249 healthy children (aged 13.14 ± 0.48 years). Analysis of the Val66Met polymorphism of the BDNF gene was performed by polymerase chain reaction (PCR) and PCR products were digested by PmlI. The prevalence of the Val66Met polymorphisms (Val/Val, Val/Met, and Met/Met) was 61.7%, 33.5%, and 4.8% in asthmatics, respectively, and 47.0%, 51.8%, and 1.2% in healthy subjects, respectively. We observed a significant association of the Met/Met variant genotype with asthmatics (OR = 4.17, 95% CI = 1.16-14.96, P = 0.018). The Val/Met genotype was protective against bronchial asthma (OR = 0.69, 95% CI = 0.48-0.99, P = 0.045), especially in girls (OR = 0.34, 95% CI = 0.20-0.59, P = 0.001). Specific BDNF gene polymorphism may contribute to bronchial asthma susceptibility. Our study suggested the positive association between selected functional BDNF polymorphism (rs6265) and asthma in children.

Transient receptor potential channels and occupational exposure

The discovery that a number of transient receptor potential (TRP) channels are expressed in a subpopulation of primary sensory neurons innervating the upper and lower airways as well as in nonneuronal cells in the airways and lungs has initiated a quest for the understanding of their role in the physiology and pathophysiology of the respiratory tract. Various members of the TRP vanilloid subfamily (TRPV1, TRPV4) and the TRP ankyrin 1 (TRPA1), because of their localization in peptidergic sensory neurons, promote airway neurogenic inflammation. In particular, TRPA1, which is gated by oxidative and nitrative stress byproducts, has been found to mediate inflammatory responses produced by an unprecedented series of toxic and irritant agents produced by air pollution, contained in cigarette smoke, and produced by accidental events at the workplace. The observation that reactive molecules endogenously produced in the airways/lungs of asthma, work-related asthma, and chronic obstructive pulmonary disease target TRPA1 underscores the primary role of the TRPA1 channel in these conditions. Identification of TRP channels, and especially TRPA1, as major targets of oxidative/nitrative stress and a variety of irritant environmental agents supports the hypothesis that neurogenic inflammation plays an important role in work-related inflammatory diseases and that antagonists for such channels may be novel therapeutic options for the treatment of these diseases.

Effects of four antitussives on airway neurogenic inflammation in a guinea pig model of chronic cough induced by cigarette smoke exposure

The effects of four antitussives, including codeine phosphate (CP), moguisteine, levodropropizine (LVDP) and naringin, on airway neurogenic inflammation and enhanced cough were investigated in guinea pig model of chronic cough. Guinea pigs were exposed to CS for 8weeks. At the 7th and 8th week, the animals were treated with vehicle, CP (4.8mg/kg), moguisteine (24mg/kg), LVDP (14mg/kg) and naringin (18.4mg/kg) respectively. Then the cough and the time-enhanced pause area under the curve (Penh-AUC) during capsaicin challenge were recorded. The substance P (SP) content, NK-1 receptor expression and neutral endopeptidase (NEP) activity in lung were determined. Chronic CS exposure induced a bi-phase time course of cough responsiveness to capsaicin. Eight weeks of CS exposure significantly enhanced the airway neurogenic inflammation and cough response in guinea pigs. Two weeks of treatment with CP, moguisteine, LVDP or naringin effectively attenuated the chronic CS-exposure enhanced cough. Only naringin exerted significant effect on inhibiting Penh-AUC, SP content and NK-1 receptor expression, as well as preventing the declining of NEP activity in lung. Chronic CS-exposed guinea pig is suitable for studying chronic pathological cough, in which naringin is effective on inhibiting both airway neurogenic inflammation and enhanced cough.

Neurogenic airway inflammation induced by repeated intra-esophageal instillation of HCl in guinea pigs

This study was conducted to investigate if repeated intra-esophageal acid administrations may induce neurogenic inflammation in the airways and nodose ganglion in a guinea pig model. Guinea pigs were sedated and perfused with 0.1N HCl in the distal esophagus via a nasoesophageal catheter for 14 consecutive days. Substance P (SP), neurokinin A (NKA), neurokinin B (NKB), and calcitonin gene-related peptide concentration were measured by ELISA or radioimmunoassay. Neuropeptide expression in the airways and nodose ganglion was detected by immunohistochemistry and assessed semi-quantitatively. Inflammation was found in the trachea and bronchi. There was a threefold increase in substance P concentration in the trachea, main bronchi, and lung homogenate and a twofold increase in NKA and NKB concentration in the main bronchi, lung homogenate, and bronchial alveolus lavage fluid, respectively. The SP and NKA expressions in the airways and nodose ganglion were also significantly increased. Chronic intra-esophageal acid instillation induces significant neurogenic inflammation in the airways and nodose ganglion in the vagus nerve in guinea pigs.

Inhaled corticosteroids inhibit substance P receptor expression in asthmatic rat airway smooth muscle cells

BackgroundNeurokinins (NKs) participate in asthmatic airway inflammation, but the effects of NKs on airway smooth muscle cells (ASMCs) and those of corticosteroids on NKs are unknown.MethodsTo investigate the effect of budesonide on substance P (NK-1) receptor (NK-1R) expression in the lung and ASMCs, 45 Wistar rats were randomly divided into three groups: control, asthmatic, and budesonide treatment. Aerosolized ovalbumin was used to generate the asthmatic rat model, and budesonide was administered after ovalbumin inhalation. On day 21, bronchial responsiveness tests, bronchoalveolar lavage, and cell counting were conducted. NK-1R protein expression in the lung was investigated by immunohistochemistry and image analysis. Primary rat ASMC cultures were established, and purified ASMCs of the fourth passage were collected for mRNA and protein studies via real-time RT-PCR, immunocytochemistry, and image analysis.ResultsNK-1R mRNA and protein expression in the budesonide treatment group rat’s lung and ASMCs were less than that in the asthmatic group but greater than that in the control group.ConclusionsNK-1R is involved in the pathogenesis of asthma and that budesonide may downregulate the expression of NK-1R in the ASMCs and airways of asthmatic rats, which may alleviate neurogenic airway inflammation.

Transient Receptor Potential Ankyrin 1 Channel Localized to Non-Neuronal Airway Cells Promotes Non-Neurogenic Inflammation

BackgroundThe transient receptor potential ankyrin 1 (TRPA1) channel, localized to airway sensory nerves, has been proposed to mediate airway inflammation evoked by allergen and cigarette smoke (CS) in rodents, via a neurogenic mechanism. However the limited clinical evidence for the role of neurogenic inflammation in asthma or chronic obstructive pulmonary disease raises an alternative possibility that airway inflammation is promoted by non-neuronal TRPA1.Methodology/Principal FindingsBy using Real-Time PCR and calcium imaging, we found that cultured human airway cells, including fibroblasts, epithelial and smooth muscle cells express functional TRPA1 channels. By using immunohistochemistry, TRPA1 staining was observed in airway epithelial and smooth muscle cells in sections taken from human airways and lung, and from airways and lung of wild-type, but not TRPA1-deficient mice. In cultured human airway epithelial and smooth muscle cells and fibroblasts, acrolein and CS extract evoked IL-8 release, a response selectively reduced by TRPA1 antagonists. Capsaicin, agonist of the transient receptor potential vanilloid 1 (TRPV1), a channel co-expressed with TRPA1 by airway sensory nerves, and acrolein or CS (TRPA1 agonists), or the neuropeptide substance P (SP), which is released from sensory nerve terminals by capsaicin, acrolein or CS), produced neurogenic inflammation in mouse airways. However, only acrolein and CS, but not capsaicin or SP, released the keratinocyte chemoattractant (CXCL-1/KC, IL-8 analogue) in bronchoalveolar lavage (BAL) fluid of wild-type mice. This effect of TRPA1 agonists was attenuated by TRPA1 antagonism or in TRPA1-deficient mice, but not by pharmacological ablation of sensory nerves.ConclusionsOur results demonstrate that, although either TRPV1 or TRPA1 activation causes airway neurogenic inflammation, solely TRPA1 activation orchestrates an additional inflammatory response which is not neurogenic. This finding suggests that non-neuronal TRPA1 in the airways is functional and potentially capable of contributing to inflammatory airway diseases.

Diagnosis and treatment of chronic cough in China: an insight into the status quo.

Chronic cough is a very common complaint in clinics throughout China. Clinical and basic science research on chronic cough started late, but in recent years the effort has yielded promising findings regarding the etiological diagnosis, treatment and pathogenesis. We found that inflammation in nonasthmatic eosinophilic bronchitis has some similarities to cough variant asthma but also a number of distinct differences. Recent evidence has also suggested a mechanistic link between airway neurogenic inflammation and and gastroesophageal reflux cough (GERC). Cough-related animal models have been developed, including models for esophageal reflux, nonasthmatic eosinophilic bronchitis and allergic rhinitis. Normal reference values for differential cell counts in induced sputum, cough sensitivity and esophageal 24-h pH monitoring in Chinese healthy subjects have been established. By using a modified algorithm for the etiological diagnosis of chronic cough, the causes of chronic cough have been investigated across a number of cities in China. The most common causes of chronic cough are cough variant asthma, eosinophilic bronchitis, upper airway cough symptoms, atopic cough and GERC, however, there are some regional variations. The Chinese National Guidelines on Diagnosis and Management of Chronic Cough were drafted in 2005, updated in 2009, and have been widely publicized and disseminated through many channels since their publication.

A guinea pig model of respiratory syncytial virus infection for cough and its neurogenic inflammatory mechanism

To establish a guinea pig model of acute and postinfectious cough caused by respiratory syncytial virus (RSV) infection and investigate the role of neurogenic inflammation in its pathogenesis. Fifty guinea pigs were randomly divided into control group and four groups of Days 6, 12, 28 and 42 after RSV inoculation (n = 10 each). The RSV suspension was inoculated by intranasal instillation. Buxco system was used to assess the cough reflex sensitivity (CRS) to inhaled capsaicin. Airway inflammation was determined by bronchoalveolar lavage fluid (BALF) cytology and lung histopathology. RSV antigen and nucleic acid were detected by immunofluorescence and real-time fluorescence quantitative PCR (polymerase chain reaction). After modeling, the content of substance P in homogenate of lung tissue was detected by ELISA (enzyme-linked immunosorbent assay) kit. The level of neurokinins receptor 1 (NK1) mRNA in lung tissue was detected by real-time PCR. The expression of substance P protein in lung tissue was detected by immunohistochemistry. The correlation analyses between CRS and the levels of substance P and NK1 mRNA were performed respectively. The viral antigen expression could be found in lung tissue of RSV infected guinea pigs. The concentration of RSV RNA content showed a gradually decreasing trend with infection time until 42 days at very low titers. The CRS values were (8.0 ± 1.2), (8.7 ± 2.0), (7.6 ± 1.4) and (6.7 ± 1.2) cough counts at Days 6, 12, 28 and 42 respectively. Compared with (2.5 ± 0.5) cough counts of control group, the CRS to capsaicin increased significantly in all animals with PIV3 inoculation (all P < 0.05) and peaked at Day 12 (P < 0.01). BALF cytology and lung tissue pathology showed airway inflammation during the acute stage of infection without pneumonia. All the contents of substance P in lung tissue homogenates increased markedly in infected groups. The immunohistochemical results of substance P in lung tissue of infected groups showed a distinct brown-yellow positive expression. In addition to Group Day 6, the NK1 mRNA contents of lung tissue in all other infection groups became elevated significantly. The correlation analysis showed a positive correlation between CRS and the levels of substance P and NK1 mRNA (all P < 0.05). A guinea pig model for cough of RSV infection has been successfully established. The elevated releases of substance P and its receptor may cause neurogenic inflammation. And airway neurogenic inflammation may play a decisive role in the heightened CRS and postinfectious cough induced by RSV.

Proliferation of sensory C-fibers and subsequent neurogenic inflammation in rat airway induced by inhaled lipopolysaccharide

Lipopolysaccharide (LPS) is associated with the development and exacerbation of airway inflammation. Increases in innervation of sensory C-fibers and tachykinin receptors, which mainly involve overproduction of neurotrophins such as nerve growth factor (NGF), may enhance neurogenic inflammation. Expression of NGF and its receptors in rat lungs is known to decline with age. We examined whether inhaled LPS causes proliferation of sensory C-fibers, increased expression of tachykinin receptors and subsequent enhancement of neurogenic inflammation in the airways of preweaning rats. Wistar male rats aged 2 weeks inhaled aerosolized LPS derived from Escherichia coli (0.1mg/ml) for 30min. Evans blue dye leakage into the trachea induced by gaseous formaldehyde or intravenous capsaicin was measured as an index of tachykinin NK1 receptor-mediated vascular permeability. Expression of substance P-immunoreactive nerves, tachykinin NK1 receptors, tumor necrosis factor (TNF)-α and NGF in the trachea was also assessed immunohistochemically. Neurogenic plasma leakage in the trachea increased significantly between 7 and 21 days after LPS inhalation. Expression of TNF-α, NGF, substance P-immunoreactive nerves and tachykinin NK1 receptors was enhanced, peaking at 28h, 7 days, 14 days and 14 days after LPS inhalation, respectively. Pretreatment with infliximab, a blocking antibody for TNF-α, almost completely abolished the airway changes seen after LPS inhalation. In conclusion, inhaled LPS increased innervation of sensory C-fibers and expression of tachykinin NK1 receptors in the airway, probably resulting in enhancement of neurogenic airway inflammation. These airway responses may be caused by overproduction of neurotrophins including NGF, mainly through a TNF-α-mediated pathway.