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

State of the art: Alternative overlap syndrome-asthma and obstructive sleep apnea

In the general population, Bronchial Asthma (BA) and Obstructive Sleep Apnea (OSA) are among the most prevalent chronic respiratory disorders. Significant epidemiologic connections and complex pathogenetic pathways link these disorders via complex interactions at genetic, epigenetic, and environmental levels. The coexistence of BA and OSA in an individual likely represents a distinct syndrome, that is, a collection of clinical manifestations attributable to several mechanisms and pathobiological signatures. To avoid terminological confusion, this association has been named alternative overlap syndrome (vs overlap syndrome represented by the chronic obstructive pulmonary disease-OSA association). This comprehensive review summarizes the complex, often bidirectional links between the constituents of the alternative overlap syndrome. Cross-sectional, population, or clinic-based studies are unlikely to elucidate causality or directionality in these relationships. Even longitudinal epidemiological evaluations in BA cohorts developing over time OSA, or OSA cohorts developing BA during follow-up cannot exclude time factors or causal influence of other known or unknown mediators. As such, a lot of pathophysiological interactions described here have suggestive evidence, biological plausibility, potential or actual directionality. By showcasing existing evidence and current knowledge gaps, the hope is that deliberate, focused, and collaborative efforts in the near-future will be geared toward opportunities to shine light on the unknowns and accelerate discovery in this field of health, clinical care, education, research, and scholarly endeavors.

Micro/nanomotors for neuromodulation

Micro-nanomotors (MNMs) are micro/nanoscale intelligent devices with vast potential in the fields of drug delivery, precision medicine, biosensing, and environmental remediation. Their primary advantage lies in their ability to convert various forms of external energy (such as magnetic, ultrasonic, and light energy) into their own propulsive force. Additionally, MNMs offer high controllability and modifiability, enabling them to navigate in the microscopic world. Importantly, recent research has harnessed the unique advantages of MNMs to synergize their capabilities in neuromodulation. This mini-review presents the significant progress and pioneering achievements in the use of MNMs for neuromodulation, with the aim of inspiring readers to explore the broader biomedical applications of these MNMs. Through continuous innovation and diligent exploration, MNMs show promise to have a profound impact on the field of biomedicine.

Exposure limits for indoor volatile substances concerning the general population: The role of population-based differences in sensory irritation of the eyes and airways for assessment factors

Assessment factors (AFs) are essential in the derivation of occupational exposure limits (OELs) and indoor air quality guidelines. The factors shall accommodate differences in sensitivity between subgroups, i.e., workers, healthy and sick people, and occupational exposure versus life-long exposure for the general population. Derivation of AFs itself is based on empirical knowledge from human and animal exposure studies with immanent uncertainty in the empirical evidence due to knowledge gaps and experimental reliability. Sensory irritation in the eyes and airways constitute about 30-40% of OELs and is an abundant symptom in non-industrial buildings characterizing the indoor air quality and general health. Intraspecies differences between subgroups of the general population should be quantified for the proposal of more 'empirical' based AFs. In this review, we focus on sensitivity differences in sensory irritation about gender, age, health status, and vulnerability in people, based solely on human exposure studies. Females are more sensitive to sensory irritation than males for few volatile substances. Older people appear less sensitive than younger ones. However, impaired defense mechanisms may increase vulnerability in the long term. Empirical evidence of sensory irritation in children is rare and limited to children down to the age of six years. Studies of the nervous system in children compared to adults suggest a higher sensitivity in children; however, some defense mechanisms are more efficient in children than in adults. Usually, exposure studies are performed with healthy subjects. Exposure studies with sick people are not representative due to the deselection of subjects with moderate or severe eye or airway diseases, which likely underestimates the sensitivity of the group of people with diseases. Psychological characterization like personality factors shows that concentrations of volatile substances far below their sensory irritation thresholds may influence the sensitivity, in part biased by odor perception. Thus, the protection of people with extreme personality traits is not feasible by an AF and other mitigation strategies are required. The available empirical evidence comprising age, lifestyle, and health supports an AF of not greater than up to 2 for sensory irritation. Further, general AFs are discouraged for derivation, rather substance-specific derivation of AFs is recommended based on the risk assessment of empirical data, deposition in the airways depending on the substance's water solubility and compensating for knowledge and experimental gaps. Modeling of sensory irritation would be a better 'empirical' starting point for derivation of AFs for children, older, and sick people, as human exposure studies are not possible (due to ethical reasons) or not generalizable (due to self-selection). Dedicated AFs may be derived for environments where dry air, high room temperature, and visually demanding tasks aggravate the eyes or airways than for places in which the workload is balanced, while indoor playgrounds might need other AFs due to physical workload and affected groups of the general population.

Exhaled biomarkers in adults with non-productive cough

BACKGROUND

Chronic cough is a common condition but disease mechanisms are not fully understood. Our aim was to study respiratory biomarkers from the small airways in individuals with non-productive cough.

METHODS

A cohort of 107 participants answered detailed questionnaires, performed spirometry, exhaled NO measurement, impulse oscillometry, gave blood samples and particles in exhaled air (PEx) samples. Current smokers (N = 38) were excluded. A total of 14 participants reported non-productive cough (cases). A total of 55 participants reported no cough (control group). PEx samples, containing exhaled particles derived from small airways, were collected and analysed with the SOMAscan proteomics platform.

RESULTS

Participants with non-productive cough had similar age, sex, BMI, and inflammation markers in blood tests, as participants without cough. The proteomics analysis found 75 proteins significantly altered among participants with chronic cough compared to controls, after adjusting for sex and investigator performing the PExA measurement (all with p-value < 0.05 and q-value ≤ 0.13, thereof 21 proteins with a q-value < 0.05). These proteins were mostly involved in immune and inflammatory responses, complement and coagulation system, but also tight junction proteins and proteins involved in neuroinflammatory responses.

CONCLUSIONS

This exploratory study on proteomics of exhaled particles among individuals with chronic cough found alterations in relative abundance of 75 proteins. The proteins identified are implicated in both pathways known to be implicated in cough, but also potentially new pathways. Further studies are needed to explore the importance of these findings.

Transient receptor potential vanilloid type-1 regulates periodontal disease damage via the PI3K/AKT signaling pathway

OBJECTIVES

This study aimed to investigate the function of transient receptor potential vanilloid 1 (TRPV1) in regulating periodontal lesions. In addition, we explored the underlying mechanism of the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway.

MATERIALS AND METHODS

Lipopolysaccharide (LPS) stimulation of human periodontal ligament cells (HPDLCs) was used to construct a periodontitis cell model, and experimental periodontitis (EP) rats were established by ligation. The mechanism by which TRPV1 regulates periodontitis was further verified by injecting the TRPV1 agonist capsaicin (CPS) and antagonist capsazepine (CPZ) into the gingiva of rats; the alveolar bone losses in each group were measured by stereomicroscopy. Real-time quantitative polymerase chain reaction (qRT-PCR) and Western blotting (WB) were used to research the expression of TRPV1 and proinflammatory cytokines, and WB was performed to test the phosphorylation of PI3K and AKT.

RESULTS

In vitro experiments showed that LPS induced the upregulation of TRPV1 and proinflammatory cytokines and promoted the phosphorylation of PI3K and AKT proteins in HPDLCs, which was consistent with their expression in the rat periodontitis model. Moreover, in vivo studies indicated that CPZ had anti-inflammatory effects through the PI3K/AKT pathway and inhibited bone loss induced by periodontal ligation in rats, while CPS had the opposite effect.

CONCLUSION

TRPV1 was involved in the process of alveolar bone defects and the inflammatory response in rats with periodontitis induced by ligation. Its mechanism might be related to the phosphorylation of related proteins in the PI3K/AKT signaling pathway.

Elucidation of Mechanisms in Cu (II) Caused Hypercontraction of Rat Tracheal Rings

Airway smooth muscle contraction is one of the primary factors involved in the initiation and progression of asthma which in turn is regulated by increased cytosolic Ca²⁺ concentration from intracellular stores and through transmembrane ion channels. Calcium-independent factors such as reactive oxygen species (ROS) generation, nitric oxide (NO) depletion and cyclooxygenase (COX) pathways also contribute to tracheal smooth muscle contraction. Studies on copper toxicity suggest significance of this essential micronutrient overdose in acute respiratory disorders, allergic asthma and ciliary motion in tracheal explants. However, the mechanism of copper caused hypercontraction upon direct exposure to tracheal smooth muscle is largely unknown. In this study we investigate the effect of copper exposure on isolated tracheal rings and relative contributions of various factors in acetylcholine-induced contractions. Results obtained suggest that rise in intracellular calcium concentration via voltage-operated Ca²⁺ channel (VOCC), store-operated Ca²⁺ channel (SOCC), stretch-activated channels (SAC) and TRP channel (transient receptor potential channel) activation is the major factor in copper-mediated hypercontraction. ROS generation or COX-dependent pathways do not appear to significantly contribute to Cu²⁺ caused hypercontraction.

The Impact of Ambient Environmental and Occupational Pollution on Respiratory Diseases

Ambient pollutants and occupational pollutants may cause and exacerbate various lung and respiratory diseases. This review describes lung and respiratory diseases in relation to ambient pollutants, particularly particulate matter (PM2.5), and occupational air pollutants, excluding communicable diseases and indoor pollutants, including tobacco smoke exposure. PM2.5 produced by combustion is an important ambient pollutant. PM2.5 can cause asthma attacks and exacerbations of chronic obstructive pulmonary disease in the short term. Further, it not only carries a risk of lung cancer and death, but also hinders the development of lung function in children in the long term. It has recently been suggested that air pollution, such as PM2.5, is a risk factor for severe coronavirus disease (COVID-19). Asbestos, which causes asbestosis, lung cancer, and malignant mesothelioma, and crystalline silica, which cause silicosis, are well-known traditional occupational pollutants leading to pneumoconiosis. While work-related asthma (WRA) is the most common occupational lung disease in recent years, many different agents cause WRA, including natural and synthetic chemicals and irritant gases. Primary preventive interventions that increase awareness of pollutants and reduce the development and exacerbation of diseases caused by air pollutants are paramount to addressing ambient and occupational pollution.

Comparative effects of capsaicin in chronic obstructive pulmonary disease and asthma (Review)

Chronic obstructive pulmonary disease (COPD) and asthma are chronic respiratory diseases with high prevalence and mortality that significantly alter the quality of life in affected patients. While the cellular and molecular mechanisms engaged in the development and evolution of these two conditions are different, COPD and asthma share a wide array of symptoms and clinical signs that may impede differential diagnosis. However, the distinct signaling pathways regulating cough and airway hyperresponsiveness employ the interaction of different cells, molecules, and receptors. Transient receptor potential cation channel subfamily V member 1 (TRPV1) plays a major role in cough and airway inflammation. Consequently, its agonist, capsaicin, is of substantial interest in exploring the cellular effects and regulatory pathways that mediate these respiratory conditions. Increasingly more studies emphasize the use of capsaicin for the inhalation cough challenge, yet the involvement of TRPV1 in cough, bronchoconstriction, and the initiation of inflammation has not been entirely revealed. This review outlines a comparative perspective on the effects of capsaicin and its receptor in the pathophysiology of COPD and asthma, underlying the complex entanglement of molecular signals that bridge the alteration of cellular function with the multitude of clinical effects.

Classification of chemicals as respiratory allergens based on human data: Requirements and practical considerations

Occupational asthma is an important health problem that can include exacerbation of existing asthma, or induce new asthma either through allergic sensitisation, or non-immunological mechanisms. While allergic sensitisation of the respiratory tract can be acquired to proteins, or to low molecular weight chemicals (chemical respiratory allergens) this article is on the latter exclusively. Chemical respiratory allergy resulting in occupational asthma is associated with high levels of morbidity and there is a need, therefore, that chemicals which can cause sensitisation of the respiratory tract are identified accurately. However, there are available no validated, or even widely accepted, predictive test methods (in vivo, in vitro or in silico) that have achieved regulatory acceptance for identifying respiratory sensitising hazards. For this reason there is an important reliance on human data for the identification of chemical respiratory allergens, and for distinguishing these from chemicals that cause occupational asthma through non-immunological mechanisms. In this article the reasons why it is important that care is taken in designating chemicals as respiratory allergens are reviewed. The value and limitations of human data that can aid the accurate identification of chemical respiratory allergens are explored, including exposure conditions, response characteristics in specific inhalation challenge tests, and immunological investigations.

A TRiP Through the Roles of Transient Receptor Potential Cation Channels in Type 2 Upper Airway Inflammation

PURPOSE OF REVIEW

Despite their high prevalence, the pathophysiology of allergic rhinitis (AR) and chronic rhinosinusitis (CRS) remains unclear. Recently, transient receptor potential (TRP) cation channels emerged as important players in type 2 upper airway inflammatory disorders. In this review, we aim to discuss known and yet to be explored roles of TRP channels in the pathophysiology of AR and CRS with nasal polyps.

RECENT FINDINGS

TRP channels participate in a plethora of cellular functions and are expressed on T cells, mast cells, respiratory epithelial cells, and sensory neurons of the upper airways. In chronic upper airway inflammation, TRP vanilloid 1 is mostly studied in relation to nasal hyperreactivity. Several other TRP channels such as TRP vanilloid 4, TRP ankyrin 1, TRP melastatin channels, and TRP canonical channels also have important functions, rendering them potential targets for therapy. The role of TRP channels in type 2 inflammatory upper airway diseases is steadily being uncovered and increasingly recognized. Modulation of TRP channels may offer therapeutic perspectives.

TRP Channels as Cellular Targets of Particulate Matter

Particulate matter (PM) is constituted by particles with sizes in the nanometer to micrometer scales. PM can be generated from natural sources such as sandstorms and wildfires, and from human activities, including combustion of fuels, manufacturing and construction or specially engineered for applications in biotechnology, food industry, cosmetics, electronics, etc. Due to their small size PM can penetrate biological tissues, interact with cellular components and induce noxious effects such as disruptions of the cytoskeleton and membranes and the generation of reactive oxygen species. Here, we provide an overview on the actions of PM on transient receptor potential (TRP) proteins, a superfamily of cation-permeable channels with crucial roles in cell signaling. Their expression in epithelial cells and sensory innervation and their high sensitivity to chemical, thermal and mechanical stimuli makes TRP channels prime targets in the major entry routes of noxious PM, which may result in respiratory, metabolic and cardiovascular disorders. On the other hand, the interactions between TRP channel and engineered nanoparticles may be used for targeted drug delivery. We emphasize in that much further research is required to fully characterize the mechanisms underlying PM-TRP channel interactions and their relevance for PM toxicology and biomedical applications.

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.

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.

Nutraceuticals in the Treatment of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a severe disease characterized by the loss and obstructive remodeling of the pulmonary arterial wall, causing a rise in pulmonary arterial pressure and pulmonary vascular resistance, which is responsible for right heart failure, functional decline, and death. Although many drugs are available for the treatment of this condition, it continues to be life-threatening, and its long-term treatment is expensive. On the other hand, many natural compounds present in food have beneficial effects on several cardiovascular conditions. Several studies have explored many of the potential beneficial effects of natural plant products on PAH. However, the mechanisms by which natural products, such as nutraceuticals, exert protective and therapeutic effects on PAH are not fully understood. In this review, we analyze the current knowledge on nutraceuticals and their potential use in the protection and treatment of PAH, as well as whether nutraceuticals could enhance the effects of drugs used in PAH through similar mechanisms.

Causes and Phenotypes of Work-Related Asthma

Work-related asthma (WRA) includes heterogeneous conditions, which have in common (i) symptoms and signs compatible with asthma and (ii) a relationship with exposures in the workplace. The types of WRA described in this review are distinguished by their etiology, comprising of work-exacerbated asthma (WEA), irritant-induced asthma (IIA), and immunologic occupational asthma (OA). There have been significant advances in the definition and characterization of the different forms of WRA by international panels of experts. The present review provides a comprehensive and updated view of the current knowledge on causes and phenotypes of WRA. Health care practitioners should consider WRA in any case of adult asthma, given that one fifth of workers with asthma report symptoms of WEA and it has been estimated that OA represents 10% to 25% of asthma in adulthood. The information provided in this review will facilitate the physician in the recognition of the different forms of WRA, since it has been established that five categories of agents are responsible for at least 60% of WEA cases and seven groups of agents are the cause of 70% of immunologic OA. In addition, there is agreement that IIA can be elicited not only by a single massive irritant exposure, but also by low/moderate repeated irritant exposures.

Pulmonary manifestations of gastroesophageal reflux disease

INTRODUCTION

Gastroesophageal reflux disease (GERD) is a widespread condition with a significant impact on the quality of life and healthcare resources. In addition to its gastrointestinal problems, GERD has been linked to a variety of respiratory diseases either as a direct cause, or as a risk factor to the inability to control or worsening of the disease.

AREAS COVERED

We performed a literature search in the PubMed database for articles addressing GERD and pulmonary diseases. This review will discuss several different pulmonary diseases affected by GERD ranging from upper airway including chronic cough, vocal cord dysfunction, lower airway diseases including COPD, asthma, and bronchiolitis obliterans syndrome to parenchymal diseases such as interstitial lung diseases. The review will discuss several different pulmonary manifestations of GERD and their contribution to patient mortality and morbidity. It will also review the mechanisms leading to these diseases, diagnostic workup, and the role of the available treatment options.

EXPERT OPINION

GERD is often overlooked as a cause of respiratory symptoms and illnesses. The literature is sparse on the relation between GERD and respiratory diseases such as interstitial lung diseases and bronchiolitis obliterans including its role in pathogenesis, mechanisms of lung injury, and whether treatment of GERD is effective in managing such illnesses.

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.

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.

Multifunctional TRPV1 Ion Channels in Physiology and Pathology with Focus on the Brain, Vasculature, and Some Visceral Systems

TRPV1 has been originally cloned as the heat and capsaicin receptor implicated in acute pain signalling, while further research has shifted the focus to its importance in chronic pain caused by inflammation and associated with this TRPV1 sensitization. However, accumulating evidence suggests that, apart from pain signalling, TRPV1 subserves many other unrelated to nociception functions in the nervous system. In the brain, TRPV1 can modulate synaptic transmission via both pre- and postsynaptic mechanisms and there is a functional crosstalk between GABA receptors and TRPV1. Other fundamental processes include TRPV1 role in plasticity, microglia-to-neuron communication, and brain development. Moreover, TRPV1 is widely expressed in the peripheral tissues, including the vasculature, gastrointestinal tract, urinary bladder, epithelial cells, and the cells of the immune system. TRPV1 can be activated by a large array of physical (heat, mechanical stimuli) and chemical factors (e.g., protons, capsaicin, resiniferatoxin, and endogenous ligands, such as endovanilloids). This causes two general cell effects, membrane depolarization and calcium influx, thus triggering depending on the cell-type diverse functional responses ranging from neuronal excitation to secretion and smooth muscle contraction. Here, we review recent research on the diverse TRPV1 functions with focus on the brain, vasculature, and some visceral systems as the basis of our better understanding of TRPV1 role in different human disorders.

Assessment of Occupational Health Hazards Due to Particulate Matter Originated from Spices

Spices have been known for their various health activities; however, they also possess the allergic potential for the respiratory system and the skin as they are fine particulate matter. Persons involved in spice agriculture and food industries are at greater risk since they are exposed to a considerable amount of combustible dust, which may be the cause of fire and explosion and adversely affect the health. These workers may experience allergy, long-term and short-term respiratory issues including occupational asthma, dermatitis, etc. Some spices induce T cell-based inflammatory reaction upon contact recognition of the antigen. Antigen Presenting Cells (APC) on binding to the causative metabolite results in activation of macrophages by allergen cytokine interleukin (IL)-12 and tumor necrosis factor-beta (TNF). Cross-reactivity for protein allergens is another factor which seems to be a significant trigger for the stimulation of allergic reactions. Thus, it was imperative to perform a systematic review along with bioinformatics based representation of some evident allergens has been done to identify the overall conservation of epitopes. In the present manuscript, we have covered a multifold approach, i.e., to categorize the spice particles based on a clear understanding about nature, origin, mechanisms; to assess metabolic reactions of the particles after exposure as well as knowledge on the conditions of exposure along with associated potential health effects. Another aim of this study is to provide some suggestions to prevent and to control the exposure up to some extent.

The Regulation of Pulmonary Vascular Tone by Neuropeptides and the Implications for Pulmonary Hypertension

Pulmonary hypertension (PH) is an incurable, chronic disease of small pulmonary vessels. Progressive remodeling of the pulmonary vasculature results in increased pulmonary vascular resistance (PVR). This causes secondary right heart failure. PVR is tightly regulated by a range of pulmonary vasodilators and constrictors. Endothelium-derived substances form the basis of most current PH treatments. This is particularly the case for pulmonary arterial hypertension. The major limitation of current treatments is their inability to reverse morphological changes. Thus, there is an unmet need for novel therapies to reduce the morbidity and mortality in PH. Microvessels in the lungs are highly innervated by sensory C fibers. Substance P and calcitonin gene-related peptide (CGRP) are released from C-fiber nerve endings. These neuropeptides can directly regulate vascular tone. Substance P tends to act as a vasoconstrictor in the pulmonary circulation and it increases in the lungs during experimental PH. The receptor for substance P, neurokinin 1 (NK1R), mediates increased pulmonary pressure. Deactivation of NK1R with antagonists, or depletion of substance P prevents PH development. CGRP is a potent pulmonary vasodilator. CGRP receptor antagonists cause elevated pulmonary pressure. Thus, the balance of these peptides is crucial within the pulmonary circulation (Graphical Abstract). Limited progress has been made in understanding their impact on pulmonary pathophysiology. This is an intriguing area of investigation to pursue. It may lead to promising new candidate therapies to combat this fatal disease. This review provides a summary of the current knowledge in this area. It also explores possible future directions for neuropeptides in PH.

TRPV1 Blocking Alleviates Airway Inflammation and Remodeling in a Chronic Asthma Murine Model

Purpose

Asthma is a chronic inflammatory airway disease characterized by airway hyperresponsiveness (AHR), inflammation, and remodeling. There is emerging interest in the involvement of the transient receptor potential vanilloid 1 (TRPV1) channel in the pathophysiology of asthma. This study examined whether TRPV1 antagonism alleviates asthma features in a murine model of chronic asthma.

Methods

BALB/c mice were sensitized to and challenged by ovalbumin to develop chronic asthma. Capsazepine (TRPV1 antagonist) or TRPV1 small interfering RNA (siRNA) was administered in the treatment group to evaluate the effect of TPV1 antagonism on AHR, airway inflammation, and remodeling.

Results

The mice displayed increased AHR, airway inflammation, and remodeling. Treatment with capsazepine or TRPV1 siRNA reduced AHR to methacholine and airway inflammation. Type 2 T helper (Th2) cytokines (interleukin [IL]-4, IL-5, and IL-13) were reduced and epithelial cell-derived cytokines (thymic stromal lymphopoietin [TSLP], IL-33, and IL-25), which regulate Th2 cytokine-associated inflammation, were also reduced. Airway remodeling characterized by goblet cell hyperplasia, increased α-smooth muscle action, and collagen deposition was also alleviated by both treatments.

Conclusions

Treatment directed at TRPV1 significantly alleviated AHR, airway inflammation, and remodeling in a chronic asthma murine model. The TRPV1 receptor can be a potential drug target for chronic bronchial asthma.

Chemical warfare agents. Classes and targets

Synthetic toxic chemicals (toxicants) and biological poisons (toxins) have been developed as chemical warfare agents in the last century. At the time of their initial consideration as chemical weapon, only restricted knowledge existed about their mechanisms of action. There exist two different types of acute toxic action: nonspecific cytotoxic mechanisms with multiple chemo-biological interactions versus specific mechanisms that tend to have just a single or a few target biomolecules. TRPV1- and TRPA-receptors are often involved as chemosensors that induce neurogenic inflammation. The present work briefly surveys classes and toxicologically relevant features of chemical warfare agents and describes mechanisms of toxic action.

Acute effects of ambient temperature and particulate air pollution on fractional exhaled nitric oxide: A panel study among diabetic patients in Shanghai, China

Background

Epidemiological studies have shown the associations of ambient temperature and particulate matter (PM) air pollution with respiratory morbidity and mortality. However, the underlying mechanisms have not been well characterized. The aim of this study is to investigate the associations of temperature and fine and coarse PM with fractional exhaled nitric oxide (FeNO), a well-established biomarker of respiratory inflammation.

Methods

We conducted a longitudinal panel study involving six repeated FeNO tests among 33 type 2 diabetes mellitus patients from April to June 2013 in Shanghai, China. Hourly temperature and PM concentrations were obtained from a nearby fixed-site monitoring station. We then explored the associations between temperature, PM, and FeNO using linear mixed-effect models incorporated with distributed lag nonlinear models for the lagged and nonlinear associations. The interactions between temperature and PM were evaluated using stratification analyses.

Results

We found that both low and high temperature, as well as increased fine and coarse PM, were significantly associated with FeNO. The cumulative relative risk of FeNO was 1.75% (95% confidence interval [CI], 1.04–2.94) comparing 15 °C to the referent temperature (24 °C) over lags 0–9 days. A 10 μg/m³ increase in fine and coarse PM concentrations were associated with 1.18% (95% CI, 0.18–2.20) and 1.85% (95% CI, 0.62–3.09) FeNO in lag 0–1 days, respectively. PM had stronger effects on cool days than on warm days.

Conclusions

This study suggested low ambient temperature, fine PM, and coarse PM might elevate the levels of respiratory inflammation. Our findings may help understand the epidemiological evidence linking temperature, particulate air pollution, and respiratory health.

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Both low and high temperatures were significantly associated with FeNO.

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The increases of fine and coarse PM concentrations were associated with FeNO.

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Both fine and coarse PM had stronger effects in cool days.

Sodium tanshinone IIA sulfonate stimulated Cl- secretion in mouse trachea

Sodium tanshinone IIA sulfonate (STS) is a derivate of tanshinone IIA, a lipophilic compound in Salvia miltiorrhiza. This study aimed to investigate the effect of STS on ion transport in mouse tracheal epithelium and the mechanisms underlying it. Short-circuit current (I_sc) was measured to evaluate the effect of STS on transepithelial ion transport. Intracellular Ca²⁺ imaging was performed to observe intracellular Ca²⁺ concentration ([Ca²⁺]_i) changes induced by STS in primary cultured mouse tracheal epithelial cells. Results showed that the apical application of STS at mouse trachea elicited an increase of I_sc, which was abrogated by atropine, an antagonist of muscarinic acetylcholine receptor (mAChR). By removing ambient Cl⁻ or applying blockers of Ca²⁺-activated Cl⁻ channel (CaCC), the response of STS-induced I_sc was suppressed. Moreover, STS elevated the [Ca²⁺]_i in mouse tracheal epithelial cells. As a result, STS stimulated Cl⁻ secretion in mouse tracheal epithelium via CaCC in an mAChR-dependent way. Due to the critical role of Cl⁻ secretion in airway hydration, our findings suggested that STS may be used to ameliorate the airway dehydration symptom in cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD).

Capsaicin pretreatment reversed pulmonary arterial hypertension by alleviating inflammation via p38MAPK pathway

Purpose/Aim: Pulmonary arterial hypertension (PAH) is a lethal disease associated with pulmonary vascular remodeling as well as inflammation. As a kind of tachykinin secreted by nerves and inflammatory cells, substance P (SP) has been proved to be involved in the progression of PAH. Capsaicin can deplete substance P and provide benefits in PAH. However, the mechanism is still unclear. In this article, we aim to illustrate the possible mechanism involved in the process of capsaicin alleviating PAH.

MATERIALS AND METHODS

A single injection of monocrotaline (MCT) to male Sprague-Dawley (SD) rats was conducted to induce PAH. Capsaicin pretreatment was administered three days before MCT injection to deplete substance P. P38mitogen-activated protein kinase (p38MAPK) activator or inhibitor was given intraperitoneally after MCT injection. After 28 days, hemodynamic studies were carried out, and right ventricular systolic pressure (RVSP), right ventricular (RV)/left ventricle plus septum (LV+S), RV/body weight (BW), and lung weight (LW)/BW were recorded and calculated. In addition, the pulmonary vascular remodeling (pulmonary arterial medial wall thickness, area, perivascualr fibrosis), pro-inflammatory cytokines, the common signal pathways, such as peroxisome proliferator-activated receptor gamma (PPARγ), extracellular signal-regulated kinases (Erk), protein kinase B (Akt), and p38MAPK were also detected.

RESULTS

Capsaicin pretreatment reversed PAH, including decreasing RVSP, RV/(LV+S), RV/BW, and LW/BW, and alleviating inflammation. Phosphorylated-p38 (p-p38) MAPK was up-regulated, which was partially reversed by capsaicin pretreatment. Interestingly, expression of Akt, Erk, and PPARγ was not altered by capsaicin pretreatment. Inhibition of p38MAPK provided the same benefits with capsaicin pretreatment, whereas it failed to provide additional improvement in the presence of capsaicin. Besides, p38MAPK activator abolished the effects of capsaicin pretreatment on PAH, suggesting a key role of p38MPAK pathway in the effects of capsaicin reversing PAH.

CONCLUSIONS

Capsaicin pretreatment reversed PAH by alleviating inflammation via p38MAPK pathway.

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.

[Role of transient receptor potential vanilloid 1 in airway inflammation in asthmatic mice]

OBJECTIVE

To study the effects of the change in transient receptor potential vanilloid 1 (TRPV1) channel activity on the degree of airway inflammation in asthmatic mice.

METHODS

BALB/c mice were randomly divided into control, asthma, capsaicin (TRPV1 agonist), capsazepine (TRPV1 antagonist), and dexamethasone groups. The asthmatic mouse model was established by intraperitoneal injection of mixed ovalbumin-aluminium hydroxide solution and ultrasonic atomization with OVA for sensitization and challenge. The capsaicin, capsazepine, and dexamethasone groups were given intraperitoneal injection of capsaicin (30 μg/kg), capsazepine (10 μmol/kg), and dexamethasone (2 mg/kg) respectively, at 30 minutes before challenge. Hematoxylin and eosin staining was used to observe the degree of pulmonary inflammation. ELISA was used to measure the content of interleukin-8 (IL-8) and interleukin-13 (IL-13) in bronchoalveolar lavage fluid (BALF). Real-Time PCR was used to measure the relative content of TRPV1 mRNA in lung tissue.

RESULTS

Compared with the asthma group, the capsazepine and dexamethasone groups showed reduced pulmonary inflammation, while the capsaicin group showed aggravated pulmonary inflammation. Compared with the control group, the asthma and capsaicin groups showed increases in the content of IL-13 and IL-8 in BALF and the mRNA expression of TRPV1 in lung tissue (P<0.05). Compared with the asthma group, the capsazepine and dexamethasone groups showed reductions in the content of IL-13 and IL-8 in BALF and the mRNA expression of TRPV1 in lung tissue (P<0.05). The capsaicin group showed increases in the content of IL-13 and IL-8 in BALF (P<0.05).

CONCLUSIONS

TRPV1 channel agonist and antagonist can influence the degree of airway inflammation in asthmatic mice. Dexamethasone may reduce airway inflammation through regulating TRPV1 level.

[Role of transient receptor potential vanilloid 1 in airway inflammation in asthmatic mice]

OBJECTIVE

To study the effects of the change in transient receptor potential vanilloid 1 (TRPV1) channel activity on the degree of airway inflammation in asthmatic mice.

METHODS

BALB/c mice were randomly divided into control, asthma, capsaicin (TRPV1 agonist), capsazepine (TRPV1 antagonist), and dexamethasone groups. The asthmatic mouse model was established by intraperitoneal injection of mixed ovalbumin-aluminium hydroxide solution and ultrasonic atomization with OVA for sensitization and challenge. The capsaicin, capsazepine, and dexamethasone groups were given intraperitoneal injection of capsaicin (30 μg/kg), capsazepine (10 μmol/kg), and dexamethasone (2 mg/kg) respectively, at 30 minutes before challenge. Hematoxylin and eosin staining was used to observe the degree of pulmonary inflammation. ELISA was used to measure the content of interleukin-8 (IL-8) and interleukin-13 (IL-13) in bronchoalveolar lavage fluid (BALF). Real-Time PCR was used to measure the relative content of TRPV1 mRNA in lung tissue.

RESULTS

Compared with the asthma group, the capsazepine and dexamethasone groups showed reduced pulmonary inflammation, while the capsaicin group showed aggravated pulmonary inflammation. Compared with the control group, the asthma and capsaicin groups showed increases in the content of IL-13 and IL-8 in BALF and the mRNA expression of TRPV1 in lung tissue (P<0.05). Compared with the asthma group, the capsazepine and dexamethasone groups showed reductions in the content of IL-13 and IL-8 in BALF and the mRNA expression of TRPV1 in lung tissue (P<0.05). The capsaicin group showed increases in the content of IL-13 and IL-8 in BALF (P<0.05).

CONCLUSIONS

TRPV1 channel agonist and antagonist can influence the degree of airway inflammation in asthmatic mice. Dexamethasone may reduce airway inflammation through regulating TRPV1 level.

Activation of Cold-Sensitive Channels TRPM8 and TRPA1 Inhibits the Proliferative Airway Smooth Muscle Cell Phenotype

PURPOSE

Airway smooth muscle cell (ASMC) phenotypic modulation is one of the key factors contributing to asthma. Temperature changes may induce asthma, and these changes are known to be related to the temperature-sensitive transient receptor potential channels (TS-TRPs). The present study was designed to investigate the cellular functions of cold-sensitive channels, TRPM8 and TRPA1, in the phenotypic modulation of ASMCs.

METHODS

A rat asthma model was constructed and the expression of TS-TRPs in ASM was tested. Using the agonists and antagonists for both TRPM8 and TRPA1, the effects of cold-sensitive channels on the phenotypic modulation of ASMCs were evaluated by measurement of contractile protein expression and cell proliferation and migration. Signaling pathways and matrix metalloproteinase-2 (MMP-2) activity were assayed with Western blotting and gelatin zymography.

RESULTS

TRPM8 and TRPA1 were decreased in the ASM of the rat asthma model. Icilin and menthol, agonists for TRPM8 and TRPA1, inhibited ASMC proliferation and migration induced by fetal bovine serum (FBS) or platelet-derived growth factor (PDGF). Moreover, icilin reversed the FBS-induced inhibition of the expression of contractile phenotype markers, smooth muscle α-actin, and SM22α. Icilin also antagonized the activation of p38 and MMP-2 and the repression of p21 caused by FBS.

CONCLUSIONS

Our findings show, for the first time, that the activation of TRPM8 and TRPA1 inhibits ASMC proliferative phenotype. These data suggest that TRPM8 and TRPA1 agonists may be promising new therapies for asthma.

The Transient Receptor Potential Vanilloid 1 Antagonist Capsazepine Improves the Impaired Lung Mechanics during Endotoxemia

Acute lung injury (ALI) caused by systemic inflammatory response remains a leading cause of morbidity and mortality in critically ill patients. Management of patients with sepsis is largely limited to supportive therapies, reflecting an incomplete understanding of the underlying pathophysiology. Furthermore, there have been limited advances in the treatments for ALI. In this study, lung function and a histological analysis were performed to evaluate the impact of transient receptor potential vanilloid-1 receptor (TRPV1) antagonist (capsazepine; CPZ) on the lipopolysaccharide (LPS)-induced lung injury in mice. For this, adult mice pre-treated with CPZ or vehicle received intraperitoneal injections of LPS or saline and 24 hr after, the mice were anaesthetized, and lung mechanics was evaluated. The LPS-challenged mice exhibited substantial mechanical impairment, characterized by increases in respiratory system resistance, respiratory system elastance, tissue damping and tissue elastance. The pre-treatment with CPZ prevented the increase in respiratory system resistance and decreased the increase in tissue damping during endotoxemia. In addition, mice pre-treated with CPZ had an attenuated lung injury evidenced by reduction on collapsed area of the lung parenchyma induced by LPS. This suggests that the TRPV1 antagonist capsazepine has a protective effect on lung mechanics in ALI during endotoxemia and that it may be a target for enhanced therapeutic efficacy in ALI.