Transient receptor potential genes, smoking, occupational exposures and cough in adults

Baseline Cohort Profile of the Korean Chronic Cough Registry: A Multicenter, Prospective, Observational Study

PURPOSE

The Korean Chronic Cough Registry study was initiated to characterize patients with chronic cough (CC) and investigate their outcomes in real-world clinical practice. This report aims to describe the baseline cohort profile and study protocols.

METHODS

This multicenter, prospective observational cohort study included newly referred CC patients and those already being treated for refractory or unexplained chronic cough (RUCC). Cough status was assessed using a visual analog scale, the Leicester Cough Questionnaire (LCQ), and the Cough Hypersensitivity Questionnaire (CHQ).

RESULTS

A total of 610 patients (66.9% women; median age 59.0 years) were recruited from 18 centers, with 176 being RUCC patients (28.9%). The median age at CC onset was 50.1 years, and 94.4% had adult-onset CC (≥ 19 years). The median cough duration was 4 years. Compared to newly referred CC patients, RUCC patients had a longer cough duration (6.0 years vs. 3.0 years) but had fewer symptoms and signs suggesting asthma, rhinosinusitis, or gastroesophageal acid reflux disease. Subjects with RUCC had lower LCQ scores (10.3 ± 3.3 vs. 11.6 ± 3.6; P < 0.001) and higher CHQ scores (9.1 ± 3.9 vs. 8.4 ± 4.1; P = 0.024). There were no marked differences in the characteristics of cough between refractory chronic cough and unexplained chronic cough.

CONCLUSIONS

Chronic cough typically develops in adulthood, lasting for years. Cough severity and quality of life impairment indicate the presence of unmet clinical needs and insufficient cough control in real-world clinical practice. Longitudinal follow-up is warranted to investigate the natural history and treatment outcomes.

Latent myofascial trigger points injection therapy for adult cough variant asthma: A randomized controlled trial

Background

Cough variant asthma (CVA) is a chronic inflammatory airway disease characterized by airway hyper-responsiveness (AHR), of which cough is the only symptom. The cough is a result of the contraction of the vocal cords, diaphragm, sternocleidomastoid muscle, and other respiratory related muscles caused by the AHR. Long-term chronic coughing can lead to repetitive contraction and chronic strain of the muscles involved in the head and neck, ultimately contributing to the formation of latent myofascial trigger points (MTrPs). In turn, latent MTrPs can also irritate or compress the nerves around them, triggering cough. The date indicated that latent MTrPs can induce autonomic phenomena and are effective in allergic rhinitis. But their roles in asthma are unclear. In this article, the efficacy and safety of latent MTrPs injection therapy in CVA were investigated.

Methods

This randomized controlled trial was conducted with 110 patients. Patients were assigned to the intervention or control group in a 1:1.5 ratio. Intervention group (n = 44): single injection therapy with latent MTrPs. Control group (n = 66): budesonide-formoterol plus montelukast for 8 weeks. During the 36-week follow up period, the recurrence rate at week 36, cough visual analog scale (VAS), ACT (asthma control test)-scores, ACQ5 (asthma control questionnaire)-scores, AQLQ (asthma quality of life questionnaire)-scores, proportion of using rescue medication, and adverse events were evaluated.

Results

The recurrence rate at week 36 was lower in the intervention group than in the control group (36 weeks, 5.0 vs. 34.55%, p = 0.001). There were significant differences between groups in change from baseline to 36 weeks in VAS [36 weeks, 1.70 (1.49) vs. 3.18 (2.04), p < 0.001]; ACT-score [36 weeks, 21.38 (2.65) vs. 18.53 (3.00), p < 0.001]; ACQ5-score [36 weeks, 0.85 (0.55) vs. 1.52 (0.62), p < 0.001]; AQLQ-score [36w, 174.40 (18.22) vs. 151.69 (24.04), p < 0.001]; proportion of using rescue medication (36 weeks, 5.0 vs. 29.1%, p = 0.003). Fewer adverse events occurred in the two groups.

Conclusion

Latent myofascial trigger points injection therapy provided long-acting, practical, short treatment duration and safety methods for CVA.

Clinical Trials Registration

http://www.chictr.org.cn/index.aspx, Chinese Clinical Trial Registry Center, ChiCTR2100044079.

Cough hypersensitivity and chronic cough

Chronic cough is globally prevalent across all age groups. This disorder is challenging to treat because many pulmonary and extrapulmonary conditions can present with chronic cough, and cough can also be present without any identifiable underlying cause or be refractory to therapies that improve associated conditions. Most patients with chronic cough have cough hypersensitivity, which is characterized by increased neural responsivity to a range of stimuli that affect the airways and lungs, and other tissues innervated by common nerve supplies. Cough hypersensitivity presents as excessive coughing often in response to relatively innocuous stimuli, causing significant psychophysical morbidity and affecting patients' quality of life. Understanding of the mechanisms that contribute to cough hypersensitivity and excessive coughing in different patient populations and across the lifespan is advancing and has contributed to the development of new therapies for chronic cough in adults. Owing to differences in the pathology, the organs involved and individual patient factors, treatment of chronic cough is progressing towards a personalized approach, and, in the future, novel ways to endotype patients with cough may prove valuable in management.

Effect of traffic-related air pollution on cough in adults with polymorphisms in several cough-related genes

With prevalent global air pollution, individuals with certain genetic predispositions and sensitivities are at of higher risk of developing respiratory symptoms including chronic cough. Studies to date have relied on patient-filled questionnaires in epidemiological studies to evaluate the gene-by-environment interactions. In a controlled human exposure study, we evaluated whether genetic risk score (GRS) based on cough-related single-nucleotide polymorphisms (SNPs) are associated with a cough count over 24 h post-exposure to diesel exhaust (DE), a model for traffic-related air pollution. DE is a mixture of several known air pollutants including PM_2.5, CO, NO, NO₂, and volatile organic compounds. Under closely observed circumstances, we determined that GRS constructed from 7 SNPs related to TRPA1, TRPV1, and NK-2R were correlated with cough count. Selection of channels were based on prior knowledge that SNPs in these channels lead to acute airway inflammation as a result of their increased sensitivity to particulate matter. We performed a linear regression analysis and found a significant, positive correlation between GRS and cough count following DE exposure (p = 0.002, R² = 0.61) and filtered air (FA) exposure (p = 0.028, R² = 0.37). Although that correlation was stronger for DE than for FA, we found no significant exposure-by-GRS interaction. In summary, cough-relevant GRS was associated with a higher 24 h cough count in a controlled setting, suggesting that individuals with a high GRS may be more susceptible to developing cough regardless of their exposure. The trend towards this susceptibility being more prominent in the context of traffic-related air pollution remains to be confirmed.

Trial registration: ClinicalTrial.gov NCT02236039; NCT0223603. Registered on August 11, 2014, https://clinicaltrials.gov/ct2/show/NCT02236039.

Investigating Potential TRPV1 Positive Feedback to Explain TRPV1 Upregulation in Airway Disease States

OBJECTIVE

The airway epithelium is a potential source of pathophysiology through activation of transient potential receptor vallinoid type 1 (TRPV1) channel. A positive feedback cycle caused by TRPV1 activity is hypothesised to induce upregulation and production of inflammatory cytokines, leading to exacerbations of chronic airway diseases. These cytokine and protein regulation effects were investigated in this study.

METHODS

Healthy (BEAS-2B) and cancer-derived (Calu-3) airway epithelial cell lines were assessed for changes to TRPV1 protein expression and mRNA expression following exposure to capsaicin (5 µM to 50 µM), and TRPV1 modulators including heat (43 °C), and hydrochloric acid (pH 3.4 to pH 6.4). Cytotoxicity was measured to determine the working concentration ranges of treatment. Subsequent bronchoconstriction by TRPV1 activation with capsaicin was measured on guinea pig airway tissue to confirm locally mediated activity without the action of known neuronal inputs.

RESULTS

TRPV1 protein expression was not different for all capsaicin, acidity, and heat exposures (P > 0.05), and was replicated in mRNA protein expression (P > 0.05). IL-6 and IL-8 expression were lower in BEAS-2B and Calu-3 cell lines exposed with acidity and heat (P < 0.05), but not consistently with capsaicin exposure, with potential cytotoxic effects possible.

CONCLUSIONS

TRPV1 expression was present in airway epithelial cells but its expression was not changed after activation by TRPV1 activators. Thus, it was not apparent the reason for reported TRPV1 upregulation in patients with airway disease states. More complex mechanisms are likely involved and will require further investigation.

Evaluation methods and influencing factors of cough sensitivity

Increased cough sensitivity is an important mechanism of chronic cough, and the evaluation of cough sensitivity helps understand the mechanism of cough and explore better methods to reduce cough. Evaluation methods may be direct or indirect. Direct methods include mechanical stimulation and chemical stimulation, and indirect methods include laryngeal reflex test, questionnaires, and brain functional magnetic resonance imaging (fMRI). Chemical stimulation is the most common method, while the capsaicin cough challenge test is proven and widely used. In this article, we will compare evaluation methods and explore influencing factors of cough sensitivity.

WAO-ARIA consensus on chronic cough - Part 1: Role of TRP channels in neurogenic inflammation of cough neuronal pathways

BACKGROUND

Cough features a complex peripheral and central neuronal network. The function of the chemosensitive and stretch (afferent) cough receptors is well described but partly understood. It is speculated that chronic cough reflects a neurogenic inflammation of the cough reflex, which becomes hypersensitive. This is mediated by neuromediators, cytokines, inflammatory cells, and a differential expression of neuronal (chemo/stretch) receptors, such as transient receptor potential (TRP) and purinergic P2X ion channels; yet the overall interaction of these mediators in neurogenic inflammation of cough pathways remains unclear.

OBJECTIVES

The World Allergy Organization/Allergic Rhinitis and its Impact on Asthma (WAO/ARIA) Joint Committee on Chronic Cough reviewed the current literature on neuroanatomy and pathophysiology of chronic cough. The role of TRP ion channels in pathogenic mechanisms of the hypersensitive cough reflex was also examined.

OUTCOMES

Chemoreceptors are better studied in cough neuronal pathways compared to stretch receptors, likely due to their anatomical overabundance in the respiratory tract, but also their distinctive functional properties. Central pathways are important in suppressive mechanisms and behavioral/affective aspects of chronic cough. Current evidence strongly suggests neurogenic inflammation induces a hypersensitive cough reflex marked by increased expression of neuromediators, mast cells, and eosinophils, among others. TRP ion channels, mainly TRP V1/A1, are important in the pathogenesis of chronic cough due to their role in mediating chemosensitivity to various endogenous and exogenous triggers, as well as a crosstalk between neurogenic and inflammatory pathways in cough-associated airways diseases.

Advances in TRP channel drug discovery: from target validation to clinical studies

Transient receptor potential (TRP) channels are multifunctional signalling molecules with many roles in sensory perception and cellular physiology. Therefore, it is not surprising that TRP channels have been implicated in numerous diseases, including hereditary disorders caused by defects in genes encoding TRP channels (TRP channelopathies). Most TRP channels are located at the cell surface, which makes them generally accessible drug targets. Early drug discovery efforts to target TRP channels focused on pain, but as our knowledge of TRP channels and their role in health and disease has grown, these efforts have expanded into new clinical indications, ranging from respiratory disorders through neurological and psychiatric diseases to diabetes and cancer. In this Review, we discuss recent findings in TRP channel structural biology that can affect both drug development and clinical indications. We also discuss the clinical promise of novel TRP channel modulators, aimed at both established and emerging targets. Last, we address the challenges that these compounds may face in clinical practice, including the need for carefully targeted approaches to minimize potential side-effects due to the multifunctional roles of TRP channels.

Transient receptor potential channels in pulmonary chemical injuries and as countermeasure targets

The lung is highly sensitive to chemical injuries caused by exposure to threat agents in industrial or transportation accidents, occupational exposures, or deliberate use as weapons of mass destruction (WMD). There are no antidotes for the majority of the chemical threat agents and toxic inhalation hazards despite their use as WMDs for more than a century. Among several putative targets, evidence for transient receptor potential (TRP) ion channels as mediators of injury by various inhalational chemical threat agents is emerging. TRP channels are expressed in the respiratory system and are essential for homeostasis. Among TRP channels, the body of literature supporting essential roles for TRPA1, TRPV1, and TRPV4 in pulmonary chemical injuries is abundant. TRP channels mediate their function through sensory neuronal and nonneuronal pathways. TRP channels play a crucial role in complex pulmonary pathophysiologic events including, but not limited to, increased intracellular calcium levels, signal transduction, recruitment of proinflammatory cells, neurogenic inflammatory pathways, cough reflex, hampered mucus clearance, disruption of the integrity of the epithelia, pulmonary edema, and fibrosis. In this review, we summarize the role of TRP channels in chemical threat agents-induced pulmonary injuries and how these channels may serve as medical countermeasure targets for broader indications.

TRPV1 genetic polymorphisms and risk of COPD or COPD combined with PH in the Han Chinese population

COPD is a common chronic disease with genetic predisposition. TRPV1 is mainly expressed in peripheral neuron which widely exists in entire respiratory tract. In present study, we aimed to study the relationship between single nucleotide polymorphisms (SNPs) of transient receptor potential vanilloid-1 (TRPV1) and the risk of chronic obstructive pulmonary disease (COPD) or COPD combined with pulmonary hypertension (PH) in Chinese Han population. A total of 1019 individuals, including 506 healthy volunteers and 513 COPD patients (150 patients combined with PH among them) were recruited in this study. Genomic DNA were extracted and sequenced. Genotype and allele frequencies of the TRPV1 SNPs among COPD, COPD combined with PH and control groups were compared. Then, the association of TRPV1 SNPs and smoking status were analyzed. Genotype frequencies of SNP rs3744683 had a significant difference in COPD patients with PH patients compared with control (p = 0.006) or COPD patients without PH patients (p = 0.016). Likewise, SNP rs3744683 was remarkedly associated with the risk of COPD (p = 0.004) in current-smoker groups which phenomenon was not observed in nonsmoker or former-smoker groups. Compared with the control group, there was a significant difference for the distribution of SNP rs4790521 alleles in the COPD group (p = 0.041). For further, logical regression analysis showed that SNP rs3744683 genotype of “TC” was a protective factor for PH in COPD patients compared with the genotype of “TT” (OR = 0.364, 95%CI = 0.159–0.829, p = 0.016). Our findings firstly revealed the relevance between TRPV1 SNPs and the risk for COPD/COPD combined with PH.

Effect of dibenz(b,f)-1,4-oxazepine aerosol on the breathing pattern and respiratory variables by continuous recording and analysis in unanaesthetised mice

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Dibenz (b,f)-1,4-oxazepine (CR) is a riot control agent.

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Respiratory variables and breathing pattern were recorded continuously in mice.

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CR produced concentration dependent sensory irritation without pulmonary irritation.

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Concentrations below 158.2 mg/m³ showed recovery to normal breathing.

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Study shows CR causes sensory irritation only and may not cause lung injury.

A riot control agent has to be a sensory irritant of a reversible type without pulmonary irritation as the later can cause lung injury. The aim of the present study is to continuously record and analyse breathing pattern and respiratory variables of dibenz (b,f)-1,4-oxazepine (CR) in unanaesthetised mice during and after exposure. The lowest concentration of 0.65 mg/m³ did not produce any effect on the breathing pattern. As high as 500 fold increase (315.9 mg/m³) in the concentration was used and no mortality was observed. CR produced a concentration dependent sensory irritation, without pulmonary irritation or airflow obstruction, showing that it may not cause any lung injury. The sensory irritation was initiated within 5 min of exposure due to the activation of TRPA1 receptors of the upper respiratory tract. Immediate recovery of normal breath without sensory irritation was observed in all the concentrations except the highest concentration of 315.9 mg/m³. Corresponding to the sensory irritation there was concentration dependent respiratory depression. The 50 percent respiratory depression (RD₅₀) in this experiment was 152 mg/m³ and the estimated threshold limit value for occupational exposure was 4.56 mg/m³. The present study shows that CR causes sensory irritation only which is completely recoverable.

Perspectives on chronic cough in Korea

Chronic cough is a common condition, and generally affects about 3% of Korean adults with a significant influence on quality of life (QoL). Despite continued clinical and academic efforts, there are unmet needs for chronic cough prevention and management in Korea. Epidemiologically, there are two major challenges: an aging population and air pollution. Korea is one of the most rapidly aging countries, and the relative proportion of elderly to younger people is expected to double within the next two decades. Air pollution is a major concern, but there is very limited evidence on the effects of air pollutant on cough in Korean patients. Clinically, upper and lower airway diseases, such as rhinitis/rhinosinusitis and cough variant asthma/eosinophilic bronchitis, are reported to account for about 75% of chronic cough in Korean adults, which formed the basis in formulating clinical practice guidelines. However, further studies are warranted to resolve clinical uncertainty, particularly for the evaluation and treatment of upper airway conditions in chronic cough. The prevalence of gastroesophageal reflux disease (GERD) is increasing, thus its relevance to cough among Koreans may warrant re-evaluation. Infection-associated chronic cough, such as tuberculosis, is another continuing concern. The proportion of chronic refractory or unexplained cough is assumed to be 10–20% among patients visiting referral clinics for chronic cough. This review presents our perspectives on current epidemiological and clinical issues of chronic cough in Korea, and addresses major knowledge gaps and future research priorities.

An update on immunologic mechanisms in the respiratory mucosa in response to air pollutants

Every day, we breathe in more than 10,000 L of air that contains a variety of air pollutants that can pose negative consequences to lung health. The respiratory mucosa formed by the airway epithelium is the first point of contact for air pollution in the lung, functioning as a mechanical and immunologic barrier. Under normal circumstances, airway epithelial cells connected by tight junctions secrete mucus, airway surface lining fluid, host defense peptides, and antioxidants and express innate immune pattern recognition receptors to respond to inhaled foreign substances and pathogens. Under conditions of air pollution exposure, the defenses of the airway epithelium are compromised by reductions in barrier function, impaired host defense to pathogens, and exaggerated inflammatory responses. Central to the mechanical and immunologic changes induced by air pollution are activation of redox-sensitive pathways and a role for antioxidants in normalizing these negative effects. Genetic variants in genes important in epithelial cell function and phenotype contribute to a diversity of responses to air pollution in the population at the individual and group levels and suggest a need for personalized approaches to attenuate the respiratory mucosal immune responses to air pollution.

The Relationship of Single Nucleotide Polymorphisms in the TRPV1 Gene with Lipid Profile, Glucose, and Blood Pressure in Mexican Population

Aim: We analyzed the frequencies of the rs222749 G>A, rs222747 G>C, rs224534 G>A, and rs8065080 C > T polymorphisms in the TRPV1 gene and their relationships with biomarkers in a Mexican population. Materials and Methods: We included 195 students from two Mexican universities (72.3% female and 27.7% male, mean age, 20.8 ± 3.3 years). The biomarkers analyzed were lipid profile, glucose levels, blood pressure (BP), and body mass index. DNA was obtained from leukocytes by the dodecyltrimethylammonium bromide and cetyltrimethylammonium bromide method and polymorphisms were determined with TaqMan single nucleotide polymorphism (SNP) genotyping assays. Results: Alterations in lipid profile were total cholesterol ≥200 mg/dL in 9.7% of participants, triglycerides (TG) ≥150 mg/dL in 9.2%, high-density lipoprotein (HDL) <35 mg/dL in 6.7%, and low-density lipoprotein (LDL) ≥130 mg/dL in 6.2% of participants. Moreover, 8.2% of the subjects had BP values consistent with hypertension. The most frequent alleles were rs222749G (89.2%), rs222747G (69.2%), rs224534G (59.7%), and rs8065080T (62.3%). An analysis of the associations between the genotypic data and the biomarkers showed that the rs222749GA and rs224534GA genotypes were associated with higher diastolic and systolic BP values, respectively; the rs222747CC genotype was associated with lower LDL levels; the rs224534AA genotype was associated with higher HDL levels and lower triglycerides and LDL. The GGGC/GCAT and GGGT/GCAT haplotypes were associated with higher systolic BP. Conclusions: This study suggests a possible association between TRPV1 gene polymorphisms and BP and lipid profiles in a Mexican population.

TRPA1 gene variants hurting our feelings

TRPA1 is a Ca²⁺-permeable, non-selective cation channel that is activated by thermal and mechanical stimuli, an amazing variety of potentially noxious chemicals, and by endogenous molecules that signal tissue injury. The expression of this channel in nociceptive neurons and epithelial cells puts it at the first line of defense and makes it a key determinant of adaptive protective behaviors. For the same reasons, TRPA1 is implicated in a wide variety of disease conditions, such as acute, neuropathic, and inflammatory pains, and is postulated to be a target for therapeutic interventions against acquired diseases featuring aberrant sensory functions. The human TRPA1 gene can bare mutations that have been associated with painful conditions, such as the N855S that relates to the rare familial episodic pain syndrome, or others that have been linked to altered chemosensation in humans. Here, we review the current knowledge on this field, re-evaluating some available functional data, and pointing out the aspects that in our opinion require attention in future research. We make emphasis in that, although the availability of the human TRPA1 structure provides a unique opportunity for further developments, far more classical functional studies using electrophysiology and analysis of channel gating are also required to understand the structure-function relationship of this intriguing channel.

Salt Taste Genotype, Dietary Habits and Biomarkers of Health: No Associations in an Elderly Cohort

A small amount of emerging research has observed variations between individual sensitivity, preference and intake of salt in the presence of single nucleotide polymorphisms (SNP) on the genes encoding salt taste receptors. Sodium intake is a significant risk factor for common diseases in elderly populations such as hypertension and cardiovascular disease; however, this does not fully explain the risk. Research into the influence of salt taste genetics on diet quality is yet to be undertaken and current research on indicators of health is limited and mixed in the direction of associations. Therefore, a secondary analysis of data from a well-characterised elderly cohort (the cross-sectional Retirement Health and Lifestyle Study, n = 536) was conducted to explore relationships between the salt taste-related SNP TRPV1-rs8065080 (assessed by Taqman genotyping assay), dietary habits and biomarkers of health. Data were analysed with standard least squares regression modelling and Tukey’s HSD post hoc tests. No association was found between the TRPV1-rs8065080 genotype, sodium intake or multiple diet quality indices (assessed by food frequency questionnaire). Sodium-related markers of health including blood pressure and markers of kidney function (urinary creatinine and albumin/creatinine ratio) and general health markers, such as Body Mass Index (BMI), were also not related to TRPV1-rs8065080 genotype. To date, this study is the most comprehensive investigation conducted to determine if the TRPV1-rs8065080 genotype relates to sodium intake and health markers influenced by sodium intake. Although no significant relationships were found, these findings are an important contribution to the limited body of knowledge surround this SNP. In addition to further research across other ages and cultures, the TRPV1-rs8065080 genotype may interact with other ion channels, and so further studies are required to determine if polymorphic variations influence sodium intake, diet and health.

Herbal Combinational Medication of Glycyrrhiza glabra, Agastache rugosa Containing Glycyrrhizic Acid, Tilianin Inhibits Neutrophilic Lung Inflammation by Affecting CXCL2, Interleukin-17/STAT3 Signal Pathways in a Murine Model of COPD

Chronic obstructive pulmonary disease (COPD) is caused by exposure to toxic particles, such as coal fly ash (CFA), diesel-exhaust particle (DEP), and cigarette smoke (CS), leading to chronic bronchitis, mucus production, and a subsequent lung dysfunction. This study, using a mouse model of COPD, aimed to evaluate the effect of herbal combinational medication of Glycyrrhiza glabra (GG), Agastache rugosa (AR) containing glycyrrhizic acid (GA), and tilianin (TN) as active ingredients. GA, a major active component of GG, possesses a range of pharmacological and biological activities including anti-inflammatory, anti-allergic, anti-oxidative. TN is a major flavonoid that is present in AR. It has been reported to have anti-inflammatory effects of potential utility as an anti-COPD agent. The COPD in the mice model was induced by a challenge with CFA and DEP. BALB/c mice received CFA and DEP alternately three times for 2 weeks to induce COPD. The herbal mixture of GG, AR, and TN significantly decreased the number of neutrophils in the lungs and bronchoalveolar lavage (BAL) fluid. It also significantly reduced the production of C-X-C motif chemokine ligand 2 (CXCL-2), IL-17A, CXCL-1, TNF-α, symmetric dimethylarginine (SDMA) in BALF and CXCL-2, IL-17A, CXCL-1, MUC5AC, transient receptor potential vanilloid-1 (TRPV1), IL-6, COX-2, NOS-II, and TNF-α mRNA expression in the lung tissue. Notably, a combination of GG and AR was more effective at regulating such therapeutic targets than GG or AR alone. The histolopathological lung injury was alleviated by treatment with the herbal mixture and their active ingredients (especially TN). In this study, the herbal combinational mixture more effectively inhibited neutrophilic airway inflammation by regulating the expression of inflammatory cytokines and CXCL-2 by blocking the IL-17/STAT3 pathway. Therefore, a herbal mixture of GG and AR may be a potential therapeutic agent to treat COPD.

Effects of inhalation of sevoflurane at different concentrations on TRPV1 in airways of rats at different developmental stages

Aim Determine changes in the expressions of the ion channel-TRPV1-and neuropeptides-NKA, NKB, calcitonin gene-related peptide (CGRP), and SP-in 14-, 21-, and 42-day-old rats after inhaling 1.5% and 2.6% sevoflurane.

MAIN METHODS

A small in-house inhalation anesthesia chamber was designed to allow 14-, 21-, and 42-day-old rats inhale 1.5% and 2.6% sevoflurane, and rats in the control group inhaled carrier gas(1 L/min air +1 L/min O₂). In addition, 14- and 21-day-old rats were pretreated with capsazepine, followed by inhalation of 1.5% and 2.6% sevoflurane or the carrier gas. The expression of TRPV1 in lung tissues was detected by Western blotting, whereas the expressions of NKA, NKB, CGRP, and SP in the trachea were detected by immunohistochemistry.

KEY FINDINGS

After inhalation of 1.5% sevoflurane, the expression of TRPV1 in the lung tissues of 14- and 21-day-old rats was significantly increased compared with that in the control group, which was antagonized by capsazepine pretreatment. Moreover, inhalation of 1.5% sevoflurane markedly increased the expressions of NKA, NKB, CGRP, and SP in the trachea of 21-day-old rats and of NKB, CGRP, and SP in the trachea of 14-day-old rats. The expressions of these molecules were antagonized by capsazepine pretreatment. Conversely, inhalation of 2.6% sevoflurane decreased the expressions of NKA and NKB in the trachea of 42-day-old rats.

SIGNIFICANCE

Sevoflurane did not upregulate the expression of TRPV1 in the airways of late-developing rats. This anesthetic may have a two-way effect on airways, resulting in considerable effects in pediatric clinical anesthesia management.

Multiple single nucleotide polymorphisms of the transient receptor potential vanilloid 1 (TRPV1) genes associate with cough sensitivity to capsaicin in healthy subjects

BACKGROUND

Cough is a common symptom in several respiratory diseases and may occur in healthy subjects as a defense mechanism against noxious inhalants. Cough response is mediated by transient receptor potential vanilloid-1 (TRPV1) expressed by C-fibers in the airways. Capsaicin (CPS) activates TRPV1 and is regularly used as a tool to study cough response. Although single nucleotide polymorphisms (SNPs) of TRPV1 are implicated in CPS binding, their role in cough response is not fully elucidated.

AIMS

In this study we investigated the relationship between capsaicin cough challenge sensitivity and multiple TRPV1 polymorphisms.

METHODS

The dose-response of cough induced by CPS inhalation was determined in 20 unselected healthy volunteers and the concentration of CPS causing two coughs (C2) was calculated. The SNPs I585V(rs8065080), T505A(rs17633288), T469I(rs224534), I315 M(rs222747), P91S(rs222749), and K2N(rs9894618) were characterized in blood DNA from each subject. The association between combinations of TRPV1 SNPs and CPS sensitivity of each subject was assessed by linear regression.

RESULTS

All subjects were wild type for T505A and K2N, while they exhibited two to six SNPs with high capsaicin responsiveness. The major contribution to CPS sensitivity in vivo (C2) was due to four combined SNPs: 315 M, 585I, 469I and 91S (p = 0.015). We found, however, that the presence of a minimum of two polymorphisms, such as 91S combined with 315 M (p = 0.032) or 91S with 585I (p = 0.025), was sufficient to detect an effect on C2.

CONCLUSION

Capsaicin cough challenge sensitivity in healthy subjects is dependent on multiple TRPV1 polymorphisms.

Validation of antibodies for the specific detection of human TRPA1

The transient receptor potential cation channel family member ankyrin 1 (TRPA1) is a potential target for several diseases, but detection of human TRPA1 (hTRPA1) protein in cells and tissues is problematic as rigorous antibody validation is lacking. We expressed hTRPA1 in a TRPA1-negative cell line to evaluate 5 commercially available antibodies by western blotting, immunofluorescence, immunocytochemistry and flow cytometry. The three most cited anti-TRPA1 antibodies lacked sensitivity and/or specificity, but two mouse monoclonal anti-TRPA1 antibodies detected hTRPA1 specifically in the above assays. This enabled the development of a flow cytometry assay, which demonstrated strong expression of TRPA1 in human lung myofibroblasts, human airway smooth muscle cells but not lung mast cells. The most cited anti-TRPA1 antibodies lack sensitivity and/or specificity for hTRPA1. We have identified two anti-TRPA1 antibodies which detect hTRPA1 specifically. Previously published data regarding human TRPA1 protein expression may need revisiting.

The Role of Transient Receptor Potential Vanilloid 1 in Common Diseases of the Digestive Tract and the Cardiovascular and Respiratory System

Transient receptor potential vanilloid subtype 1 (TRPV1), a member of the transient receptor potential vanilloid (TRPV) channel family, is a nonselective cation channel that is widely expressed in sensory nerve fibers and nonneuronal cells, including certain vascular endothelial cells and smooth muscle cells. The activation of TRPV1 may be involved in the regulation of various physiological functions, such as the release of inflammatory mediators in the body, gastrointestinal motility function, and temperature regulation. In recent years, a large number of studies have revealed that TRPV1 plays an important role in the physiological and pathological conditions of the digestive system, cardiovascular system, and respiratory system, but there is no systematic report on TRPV1. The objective of this review is to explain the function and effects of TRPV1 on specific diseases, such as irritable bowel syndrome, hypertension, and asthma, and to further investigate the intrinsic relationship between the expression and function of TRPV1 in those diseases to find new therapeutic targets for the cure of related diseases.

Transient Receptor Potential Channels and Chronic Airway Inflammatory Diseases: A Comprehensive Review

Chronic airway inflammatory diseases remain a major problem worldwide, such that there is a need for additional therapeutic targets and novel drugs. Transient receptor potential (TRP) channels are a group of non-selective cation channels expressed throughout the body that are regulated by various stimuli. TRP channels have been identified in numerous cell types in the respiratory tract, including sensory neurons, airway epithelial cells, airway smooth muscle cells, and fibroblasts. Different types of TRP channels induce cough in sensory neurons via the vagus nerve. Permeability and cytokine production are also regulated by TRP channels in airway epithelial cells, and these channels also contribute to the modulation of bronchoconstriction. TRP channels may cooperate with other TRP channels, or act in concert with calcium-dependent potassium channels and calcium-activated chloride channel. Hence, TRP channels could be the potential therapeutic targets for chronic airway inflammatory diseases. In this review, we aim to discuss the expression profiles and physiological functions of TRP channels in the airway, and the roles they play in chronic airway inflammatory diseases.

Combined effect of acid-sensing ion channel 3 and transient receptor potential vanilloid 1 gene polymorphisms on blood pressure variations in Taiwanese

Objectives:

Both acid-sensing ion channel acid-sensing ion channel 3 (ASIC3) and transient receptor potential vanilloid 1 (TRPV1) have been proposed to be involved in the pathophysiology of hypertension. Common colocalization of ASIC3 and TRPV1 channels in the same sensory neuron has been reported. We aimed to study the combined ASIC3 and TRPV1 gene polymorphisms in the risk of hypertension.

Materials and Methods:

To test the statistical association between genetic polymorphisms of the ASIC3 and TRPV1 genes and blood pressure (BP) variations in Taiwanese, 551 unrelated individuals (286 men and 265 women) having routine health examinations were recruited. The participants had no history of cardiovascular disease or use of medication for hypertension.

Results:

Six ASIC3 and four TRPV1 gene polymorphisms were genotyped, and only the ASIC3 rs2288646 polymorphism was associated with variations in BP in the participants. In subgroup analysis, we found participants carrying the combined ASIC3 rs2288646 AA or AG and TRPV1 rs8065080 CC genotypes (combined genotypes) had significantly higher systolic, mean and diastolic BP compared with the other subgroups (P = 0.009, 0.003, and 0.006, respectively, after Bonferroni correction). Interaction analysis also revealed significant gene-gene interaction in the systolic, mean, and diastolic BP in the ASIC3 and TRPV1 genotypes (interaction P = 0.006, 0.002, and 0.002, respectively). A trend of increasing frequencies of the combined genotype was observed in normotensive, prehypertensive, and hypertensive subgroups (P for trend = 0.001), as well as in those with higher systolic and diastolic BPs (P for trend = 9.13 × 10⁻⁴ and P for trend = 5.5 × 10⁻⁵, respectively).

Conclusion:

Our data show a combined effect of ASIC3 and TRPV1 gene polymorphisms in BP variations in Taiwanese. These results suggest that the interaction between ASIC3 and TRPV1 is involved in BP regulation.

Cough and airway disease: The role of ion channels

Cough is the most common reason for patients to visit a primary care physician, yet it remains an unmet medical need. It can be idiopathic in nature but can also be a troublesome symptom across chronic lung diseases such as asthma, COPD and idiopathic pulmonary fibrosis (IPF). Chronic cough affects up to 12% of the population and yet there are no safe and effective therapies. The cough reflex is regulated by vagal, sensory afferent nerves which innervate the airway. The Transient Receptor Potential (TRP) family of ion channels are expressed on sensory nerve terminals, and when activated can evoke cough. This review focuses on the role of 4 TRP channels; TRP Vannilloid 1 (TRPV1), TRP Ankyrin 1 (TRPA1), TRP Vannilloid 4 (TRPV4) and TRP Melastatin 8 (TRPM8) and the purinergic P2X3 receptor and their possible role in chronic cough. We conclude that these ion channels, given their expression profile and their role in the activation of sensory afferents and the cough reflex, may represent excellent therapeutic targets for the treatment of respiratory symptoms in chronic lung disease.

Drugs Affecting TRP Channels

Chronic obstructive pulmonary disease (COPD) and asthma are both common respiratory diseases that are associated with airflow reduction/obstruction and pulmonary inflammation. Whilst drug therapies offer adequate symptom control for many mild to moderate asthmatic patients, severe asthmatics and COPD patients symptoms are often not controlled, and in these cases, irreversible structural damage occurs with disease progression over time. Transient receptor potential (TRP) channels, in particular TRPV1, TRPA1, TRPV4 and TRPM8, have been implicated with roles in the regulation of inflammation and autonomic nervous control of the lungs. Evidence suggests that inflammation elevates levels of activators and sensitisers of TRP channels and additionally that TRP channel expression may be increased, resulting in excessive channel activation. The enhanced activity of these channels is thought to then play a key role in the propagation and maintenance of the inflammatory disease state and neuronal symptoms such as bronchoconstriction and cough. For TRPM8 the evidence is less clear, but as with TRPV1, TRPA1 and TRPV4, antagonists are being developed by multiple companies for indications including asthma and COPD, which will help in elucidating their role in respiratory disease.

The emerging role of transient receptor potential channels in chronic lung disease

Chronic lung diseases such as asthma, chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis are a major and increasing global health burden with a high unmet need. Drug discovery efforts in this area have been largely disappointing and so new therapeutic targets are needed. Transient receptor potential ion channels are emerging as possible therapeutic targets, given their widespread expression in the lung, their role in the modulation of inflammatory and structural changes and in the production of respiratory symptoms, such as bronchospasm and cough, seen in chronic lung disease.

Next-generation sequencing of the human TRPV1 gene and the regulating co-players LTB4R and LTB4R2 based on a custom AmpliSeq™ panel

Background

Transient receptor potential cation channel subfamily V member 1 (TRPV1) are sensitive to heat, capsaicin, pungent chemicals and other noxious stimuli. They play important roles in the pain pathway where in concert with proinflammatory factors such as leukotrienes they mediate sensitization and hyperalgesia. TRPV1 is the target of several novel analgesics drugs under development and therefore, TRPV1 genetic variants might represent promising candidates for pharmacogenetic modulators of drug effects.

Methods

A next-generation sequencing (NGS) panel was created for the human TRPV1 gene and in addition, for the leukotriene receptors BLT1 and BLT2 recently described to modulate TRPV1 mediated sensitisation processes rendering the coding genes LTB4R and LTB4R2 important co-players in pharmacogenetic approaches involving TRPV1. The NGS workflow was based on a custom AmpliSeq^™ panel and designed for sequencing of human genes on an Ion PGM^™ Sequencer. A cohort of 80 healthy subjects of Western European descent was screened to evaluate and validate the detection of exomic sequences of the coding genes with 25 base pair exon padding.

Results

The amplicons covered approximately 97% of the target sequence. A median of 2.81 x 10⁶ reads per run was obtained. This identified approximately 140 chromosome loci where nucleotides deviated from the reference sequence GRCh37 hg19 comprising the three genes TRPV1, LTB4R and LTB4R2. Correspondence between NGS and Sanger derived nucleotide sequences was 100%.

Conclusions

Results suggested that the NGS approach based on AmpliSeq^™ libraries and Ion Personal Genome Machine (PGM) sequencing is a highly efficient mutation detection method. It is suitable for large-scale sequencing of TRPV1 and functionally related genes. The method adds a large amount of genetic information as a basis for complete analysis of TRPV1 ion channel genetics and its functional consequences.

Agonist-dependence of functional properties for common nonsynonymous variants of human transient receptor potential vanilloid 1

Transient receptor potential vanilloid 1 (TRPV1) is a polymodal receptor activated by capsaicin, heat, and acid, which plays critical roles in thermosensation and pain. In addition, TRPV1 also contributes to multiple pathophysiological states in respiratory, cardiovascular, metabolic, and renal systems. These contributions are further supported by evidence that variations in the human TRPV1 (hTRPV1) gene are associated with various physiological and pathological phenotypes. However, it is not well understood how the variations in hTRPV1 affect channel functions. In this study, we examined functional consequences of amino acid variations of hTRPV1 induced by 5 nonsynonymous single-nucleotide polymorphisms (SNPs) that most commonly exist in the human population. Using electrophysiological assays in HEK293 cells, we examined 9 parameters: activation, Ca permeation, and desensitization after activation by capsaicin, acid, and heat. Our results demonstrated that the 5 SNPs differentially affected functional properties of hTRPV1 in an agonist-dependent manner. Based upon the directionality of change of each phenotype and cumulative changes in each SNP, we classified the 5 SNPs into 3 presumptive functional categories: gain of function (hTRPV1 Q85R, P91S, and T469I), loss of function (I585V), and mixed (M315I). These results reveal a spectrum of functional variation among common hTRPV1 polymorphisms in humans and may aid mechanistic interpretation of phenotypes associated with nonsynonymous hTRPV1 SNPs under pathophysiological conditions.

TRPA1 gene polymorphisms and childhood asthma

BACKGROUND

Animal data have suggested that the transient receptor potential ankyrin-1 (TRPA1) ion channel plays a key role in promoting airway inflammation in asthma and may mediate effects of paracetamol on asthma, yet confirmatory human data are lacking. To study associations of TRPA1 gene variants with childhood asthma and total IgE concentration, and interactions between TRPA1 and prenatal paracetamol exposure on these outcomes.

METHODS

We analysed associations between 31 TRPA1 single nucleotide polymorphisms (SNPs) and current doctor-diagnosed asthma and total IgE concentration at 7.5 years in the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort. We sought to confirm the most significant associations with comparable outcomes in the Prevention and Incidence of Asthma and Mite Allergy (PIAMA) and Generation R birth cohorts. In ALSPAC, we explored interactions with prenatal paracetamol exposure.

RESULTS

In ALSPAC, there was strong evidence for association between six SNPs and asthma: rs959974 and rs1384001 (per-allele odds ratio for both: 1.30 (95% CI: 1.15-1.47), p = 0.00001), rs7010969 (OR 1.28 (1.13-1.46), p = 0.00004), rs3735945 (OR 1.30 (1.09-1.55), p = 0.003), rs920829 (OR 1.30 (1.09-1.54), p = 0.004) and rs4738202 (OR 1.22 (1.07-1.39), p = 0.004). In a meta-analysis across the three cohorts, the pooled effect estimates confirmed that all six SNPs were significantly associated with asthma. In ALSPAC, TRPA1 associations with asthma were not modified by prenatal paracetamol, although associations with IgE concentration were.

CONCLUSION

This study suggests that TRPA1 may play a role in the development of childhood asthma. (249 words).

Genes Interacting with Occupational Exposures to Low Molecular Weight Agents and Irritants on Adult-Onset Asthma in Three European Studies

BACKGROUND

The biological mechanisms by which cleaning products and disinfectants-an emerging risk factor-affect respiratory health remain incompletely evaluated. Studying genes by environment interactions (G × E) may help identify new genes related to adult-onset asthma.

OBJECTIVES

We identified interactions between genetic polymorphisms of a large set of genes involved in the response to oxidative stress and occupational exposures to low molecular weight (LMW) agents or irritants on adult-onset asthma.

METHODS

Our data came from three large European cohorts: Epidemiological Family-based Study of the Genetics and Environment of Asthma (EGEA), Swiss Cohort Study on Air Pollution and Lung and Heart Disease in Adults (SAPALDIA), and European Community Respiratory Health Survey in Adults (ECRHS). A candidate pathway-based strategy identified 163 genes involved in the response to oxidative stress and potentially related to exposures to LMW agents/irritants. Occupational exposures were evaluated using an asthma job-exposure matrix and job-specific questionnaires for cleaners and healthcare workers. Logistic regression models were used to detect G × E interactions, adjusted for age, sex, and population ancestry, in 2,599 adults (mean age, 47 years; 60% women, 36% exposed, 18% asthmatics). p-Values were corrected for multiple comparisons.

RESULTS

Ever exposure to LMW agents/irritants was associated with current adult-onset asthma [OR = 1.28 (95% CI: 1.04, 1.58)]. Eight single nucleotide polymorphism (SNP) by exposure interactions at five loci were found at p < 0.005: PLA2G4A (rs932476, chromosome 1), near PLA2R1 (rs2667026, chromosome 2), near RELA (rs931127, rs7949980, chromosome 11), PRKD1 (rs1958980, rs11847351, rs1958987, chromosome 14), and PRKCA (rs6504453, chromosome 17). Results were consistent across the three studies and after accounting for smoking.

CONCLUSIONS

Using a pathway-based selection process, we identified novel genes potentially involved in adult asthma by interaction with occupational exposure. These genes play a role in the NF-κB pathway, which is involved in inflammation. Citation: Rava M, Ahmed I, Kogevinas M, Le Moual N, Bouzigon E, Curjuric I, Dizier MH, Dumas O, Gonzalez JR, Imboden M, Mehta AJ, Tubert-Bitter P, Zock JP, Jarvis D, Probst-Hensch NM, Demenais F, Nadif R. 2017. Genes interacting with occupational exposures to low molecular weight agents and irritants on adult-onset asthma in three European studies. Environ Health Perspect 125:207-214; http://dx.doi.org/10.1289/EHP376.

Establishment of preliminary regulatory network of TRPV1 and related cytokines

Our purpose was to investigate the regulatory mechanism of TRPV1 and related cytokines on children bronchial asthma. TRPV1 mRNA level and two SNP genotypes of children in case group and control group were detected by real-time quantitative PCR. Western blot and ELISA were used to measure the levels of cytokines like IgE, IL-2, etc. Their correlations were analyzed by Logistic regression and KEGG analysis. Moreover, tertiary structure of protein and miRNA binding sites were also predicted by online tools. Case group was obviously different from control group in TRPV1 mRNA level, the two SNP genotypes distribution and the related cytokines levels. Logistic regression analysis further demonstrated that TRPV1 mRNA level, EOS, IL-4 and IL-5 may be risk factors for children bronchial asthma. And based on that, the preliminary regulatory network of children bronchial asthma was drawn. What’s more, mutation of rs4790521 and rs4790522 in TRPV1 gene both induced its corresponding miRNA binding site’s change. The preliminary regulatory network of TRPV1 and related cytokines on children bronchial asthma established in this study provides certain theoretical basis for pathogenesis and treatment of children bronchial asthma.

The nervous system of airways and its remodeling in inflammatory lung diseases

Inflammatory lung diseases are associated with bronchospasm, cough, dyspnea and airway hyperreactivity. The majority of these symptoms cannot be primarily explained by immune cell infiltration. Evidence has been provided that vagal efferent and afferent neurons play a pivotal role in this regard. Their functions can be altered by inflammatory mediators that induce long-lasting changes in vagal nerve activity and gene expression in both peripheral and central neurons, providing new targets for treatment of pulmonary inflammatory diseases.

Medicinal Chemistry, Pharmacology, and Clinical Implications of TRPV1 Receptor Antagonists

Transient receptor potential vanilloid 1 (TRPV1) is an ion channel expressed on sensory neurons triggering an influx of cations. TRPV1 receptors function as homotetramers responsive to heat, proinflammatory substances, lipoxygenase products, resiniferatoxin, endocannabinoids, protons, and peptide toxins. Its phosphorylation increases sensitivity to both chemical and thermal stimuli, while desensitization involves a calcium-dependent mechanism resulting in receptor dephosphorylation. TRPV1 functions as a sensor of noxious stimuli and may represent a target to avoid pain and injury. TRPV1 activation has been associated to chronic inflammatory pain and peripheral neuropathy. Its expression is also detected in nonneuronal areas such as bladder, lungs, and cochlea where TRPV1 activation is responsible for pathology development of cystitis, asthma, and hearing loss. This review offers a comprehensive overview about TRPV1 receptor in the pathophysiology of chronic pain, epilepsy, cough, bladder disorders, diabetes, obesity, and hearing loss, highlighting how drug development targeting this channel could have a clinical therapeutic potential. Furthermore, it summarizes the advances of medicinal chemistry research leading to the identification of highly selective TRPV1 antagonists and their analysis of structure-activity relationships (SARs) focusing on new strategies to target this channel.

Do chronic workplace irritant exposures cause asthma?

PURPOSE OF REVIEW

The present review summarizes the recent literature on the relation between chronic workplace irritant exposures and asthma, focusing on exposures of low to moderate levels. We discuss results from epidemiological surveys, potential biological mechanisms, and needs for further research. These aspects are largely illustrated by studies on exposure to cleaning products.

RECENT FINDINGS

Recent results from nine population-based and workplace-based epidemiological studies, mostly cross-sectional, found an increased risk of both new-onset and work-exacerbated asthma among participants exposed to moderate level of irritants and/or cleaning products.

SUMMARY

Evidence of a causal effect of chronic workplace irritant exposure in new-onset asthma remains limited, mainly because of a lack of longitudinal studies and the difficulty to evaluate irritant exposures. However, recent epidemiological studies strengthen the evidence of an effect of chronic exposure to irritants in work-related asthma. The underlying mechanism remains unknown but may be related to oxidative stress, neurogenic inflammation and dual irritant and adjuvant effects. However, disentangling chronic irritant effects from either acute irritant-induced asthma or immunological low molecular weight agent-induced asthma is difficult for some agents. Further research is needed to improve assessment of irritant exposures and identify biomarkers.

Characterization of Transient Receptor Potential Vanilloid-1 (TRPV1) Variant Activation by Coal Fly Ash Particles and Associations with Altered Transient Receptor Potential Ankyrin-1 (TRPA1) Expression and Asthma

Transient receptor potential (TRP) channels are activated by environmental particulate materials. We hypothesized that polymorphic variants of transient receptor potential vanilloid-1 (TRPV1) would be uniquely responsive to insoluble coal fly ash compared with the prototypical soluble agonist capsaicin. Furthermore, these changes would manifest as differences in lung cell responses to these agonists and perhaps correlate with changes in asthma symptom control. The TRPV1-I315M and -T469I variants were more responsive to capsaicin and coal fly ash. The I585V variant was less responsive to coal fly ash particles due to reduced translation of protein and an apparent role for Ile-585 in activation by particles. In HEK-293 cells, I585V had an inhibitory effect on wild-type TRPV1 expression, activation, and internalization/agonist-induced desensitization. In normal human bronchial epithelial cells, IL-8 secretion in response to coal fly ash treatment was reduced for cells heterozygous for TRPV1-I585V. Finally, both the I315M and I585V variants were associated with worse asthma symptom control with the effects of I315M manifesting in mild asthma and those of the I585V variant manifesting in severe, steroid-insensitive individuals. This effect may be due in part to increased transient receptor potential ankyrin-1 (TRPA1) expression by lung epithelial cells expressing the TRPV1-I585V variant. These findings suggest that specific molecular interactions control TRPV1 activation by particles, differential activation, and desensitization of TRPV1 by particles and/or other agonists, and cellular changes in the expression of TRPA1 as a result of I585V expression could contribute to variations in asthma symptom control.

Associations of Cough Prevalence with Ambient Polycyclic Aromatic Hydrocarbons, Nitrogen and Sulphur Dioxide: A Longitudinal Study

Information on potential cough triggers including environmental irritants is vital for successful management of chronic cough in patients. We investigated the relationship between ambient levels of particulate polycyclic aromatic hydrocarbons (PAH), nitrogen dioxide (NO₂) and sulphur dioxide (SO₂) exposures with cough prevalence. Eighty-three adult patients, who had been physician diagnosed with at least asthma, cough variant asthma and/or atopic cough, were divided into asthma and non-asthma groups. They recorded daily cough symptoms during 4 January-30 June 2011 study period while daily samples of total suspended particles were simultaneously collected by use of glass fiber filters and the particulate PAH content determined by high performance liquid chromatography coupled with a fluorescence detector. Ambient concentrations of NO₂ and SO₂ were obtained from a local monitoring site. Logistic regression models using generalized estimating equations were used to determine population-averaged estimates of association between cough prevalence and ambient pollutant exposures for the two groups. Fully adjusted odds ratios from single pollutant models were 1.083 (95% confidence interval (CI): 1.029, 1.140) and 1.097 (95% CI: 1.016, 1.185) per 0.57 ng/m³ for lag2 PAH exposure, while only for asthma group had significant associations with NO₂ and SO₂ exposures for both lag2 and lag02. Similar associations were observed in multipollutant models. This finding suggests that ambient PAH, NO₂, and SO₂ exposure even at low levels is related to cough prevalence in adult chronic cough patients and may be considered as aggravating factor during clinical management of the condition.

An official American Thoracic Society Workshop Report: presentations and discussion of the fifth Jack Pepys Workshop on Asthma in the Workplace. Comparisons between asthma in the workplace and non-work-related asthma

The fifth Jack Pepys Workshop on Asthma in the Workplace focused on the similarities and differences of work-related asthma (WRA) and non-work-related asthma (non-WRA). WRA includes occupational asthma (OA) and work-exacerbated asthma (WEA). There are few biological differences in the mechanisms of sensitization to environmental and occupational allergens. Non-WRA and OA, when due to high-molecular-weight agents, are both IgE mediated; it is uncertain whether OA due to low-molecular-weight agents is also IgE mediated. Risk factors for OA include female sex, a history of upper airway symptoms, and a history of bronchial hyperresponsiveness. Atopy is a risk factor for OA due to high-molecular-weight agents, and exposure to cleaning agents is a risk factor for both OA and non-WRA. WEA is important among workers with preexisting asthma and may overlap with irritant-induced asthma, a type of OA. Induced sputum cytology can confirm airway inflammation, but specific inhalation challenge is the reference standard diagnostic test. Inhalation challenges are relatively safe, with the most severe reactions occurring with low-molecular-weight agents. Indirect health care costs account for about 50% of total asthma costs. Workers with poor asthma control (WRA or non-WRA) are less likely to be employed. Income loss is a major contributor to the indirect costs of WRA. Overall, asthma outcomes probably are worse for adult-onset than for childhood-onset asthma but better for OA than adult-onset non-WRA. Important aspects of management of OA are rapid and proper confirmation of the diagnosis and reduction of exposure to sensitizers or irritants at work and home.

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.

Pollutional haze and COPD: etiology, epidemiology, pathogenesis, pathology, biological markers and therapy

In recent years, serious pollutional haze occurs in the mainland of China thanks to the development of urbanization and industrialization. There is a close relationship between air pollution and the occurrence and development of chronic obstructive pulmonary disease (COPD), but there are some new characteristics in some aspects of COPD associated with pollutional haze compared with COPD induced by traditional physical and chemical factors. This article attempts to summarize the new progress from these new features of COPD related to pollutional haze, focus on etiology, epidemiology, pathogenesis, pathology, biological markers and therapy.

α,β-Unsaturated aldehyde pollutant acrolein suppresses cardiomyocyte contractile function: Role of TRPV1 and oxidative stress

Air pollution is associated with an increased prevalence of heart disease and is known to trigger a proinflammatory response via stimulation of transient receptor potential vanilloid cation channels (TRPV1, also known as the capsaicin receptor). This study was designed to examine the effect of acrolein, an essential α,β-unsaturated aldehyde pollutant, on myocardial contractile function and the underlying mechanism involved with a focus on TRPV1 and oxidative stress. Cardiomyocyte mechanical and intracellular Ca(2+) properties were evaluated using an IonOptix MyoCam® system including peak shortening (PS), maximal velocity of shortening/relengthening (± dL/dt), time-to-PS (TPS), time-to-90% relengthening (TR90 ), fura-2 fluorescence intensity (FFI) and intracellular Ca(2+) decay. Changes in apoptosis and TRPV1 were evaluated using Western blot analysis. The degree of oxidative stress was assessed using the ratio between reduced and oxidized glutathione. Results obtained revealed that exposure of cardiomyocytes to acrolein acutely compromised contractile and intracellular Ca(2+) properties including depressed PS, ± dL/dt and ΔFFI, as well as prolonged TR90 and intracellular Ca(2+) decay. In addition, acrolein exposure upregulated TRPV1 associated with an increase in both apoptosis and oxidative stress. However, the acrolein-induced cardiomyocyte contractile and intracellular Ca(2+) anomalies, as well as apoptosis (as evidenced by Bcl-2, Bax, FasL, Caspase-3 and -8), were negated by the reactive oxygen species (ROS) scavenger glutathione or the TRPV1 antagonist capsazepine. Collectively these data suggest that the α,β-unsaturated aldehyde pollutant acrolein may play a role in the pathogenesis and sequelae of air pollution-induced heart disease via a TRPV1- and oxidative stress-dependent mechanism.

[Genetic and environmental factors of asthma and allergy: Results of the EGEA study]

INTRODUCTION AND METHODS

The EGEA study (epidemiological study on the genetics and environment of asthma, bronchial hyperresponsiveness and atopy), which combines a case-control and a family-based study of asthma case (n=2120 subjects) with three surveys over 20 years, aims to identify environmental and genetic factors associated with asthma and asthma-related phenotypes. We summarize the results of the phenotypic characterization and the investigation of environmental and genetic factors of asthma and asthma-related phenotypes obtained since 2007 in the EGEA study (42 articles).

RESULTS

Both epidemiological and genetic results confirm the heterogeneity of asthma. These results strengthen the role of the age of disease onset, the allergic status and the level of disease activity in the identification of the different phenotypes of asthma. The deleterious role of active smoking, exposure to air pollution, occupational asthmogenic agents and cleaning products on the prevalence and/or activity of asthma has been confirmed. Accounting for gene-environment interactions allowed the identification of new genetic factors underlying asthma and asthma-related traits and better understanding of their mode of action.

CONCLUSION

The EGEA study is contributing to the advances in respiratory research at the international level. The new phenotypic, environmental and biological data available in EGEA study will help characterizing the long-term evolution of asthma and the factors associated to this evolution.

Targeting TRP channels for chronic cough: from bench to bedside

Cough is currently the most common reason for patients to visit a primary care physician in the UK, yet it remains an unmet medical need. Current therapies have limited efficacy or have potentially dangerous side effects. Under normal circumstances, cough is a protective reflex to clear the lungs of harmful particles; however, in disease, cough can become excessive, dramatically impacting patients' lives. In many cases, this condition is linked to inflammatory diseases such as asthma and chronic obstructive pulmonary disease (COPD), but can also be refractory to treatment and idiopathic in nature. Therefore, there is an urgent need to develop therapies, and targeting the sensory afferent arm of the reflex which initiates the cough reflex may uncover novel therapeutic targets. The cough reflex is initiated following activation of ion channels present on vagal sensory afferents. These ion channels include the transient receptor potential (TRP) family of cation-selective ion channels which act as cellular sensors and respond to changes in the external environment. Many direct activators of TRP channels, including arachidonic acid derivatives, a lowered airway pH, changes in temperature, and altered airway osmolarity are present in the diseased airway where responses to challenge agents which activate airway sensory nerve activity are known to be enhanced. Furthermore, the expression of some TRP channels is increased in airway disease. Together, this makes them promising targets for the treatment of chronic cough. This review will cover the current understanding of the role of the TRP family of ion channels in the activation of airway sensory nerves and cough, focusing on four members, transient receptor potential vanilloid (TRPV) 1, transient receptor potential ankyrin (TRPA) 1, TRPV4, and transient receptor potential melastatin (TRPM) 8 as these represent the channels where most information has been gathered with relevance to the airways. We will describe recent data and highlight the possible therapeutic utility of specific TRP channel antagonists as antitussives in the clinic.

TRP Channels in Respiratory Pathophysiology: the Role of Oxidative, Chemical Irritant and Temperature Stimuli

There is rapidly growing evidence indicating multiple and important roles of Ca(2+)- permeable cation TRP channels in the airways, both under normal and disease conditions. The aim of this review was to summarize the current knowledge of TRP channels in sensing oxidative, chemical irritant and temperature stimuli by discussing expression and function of several TRP channels in relevant cell types within the respiratory tract, ranging from sensory neurons to airway smooth muscle and epithelial cells. Several of these channels, such as TRPM2, TRPM8, TRPA1 and TRPV1, are discussed in much detail to show that they perform diverse, and often overlapping or contributory, roles in airway hyperreactivity, inflammation, asthma, chronic obstructive pulmonary disease and other respiratory disorders. These include TRPM2 involvement in the disruption of the bronchial epithelial tight junctions during oxidative stress, important roles of TRPA1 and TRPV1 channels in airway inflammation, hyperresponsiveness, chronic cough, and hyperplasia of airway smooth muscles, as well as TRPM8 role in COPD and mucus hypersecretion. Thus, there is increasing evidence that TRP channels not only function as an integral part of the important endogenous protective mechanisms of the respiratory tract capable of detecting and ensuring proper physiological responses to various oxidative, chemical irritant and temperature stimuli, but that altered expression, activation and regulation of these channels may also contribute to the pathogenesis of respiratory diseases.