Cold temperature induces mucin hypersecretion from normal human bronchial epithelial cells in vitro through a transient receptor potential melastatin 8 (TRPM8)-mediated mechanism

Novel insights into the study of goblet cell hypersecretion in allergic rhinitis

Goblet cell hypersecretion is a hallmark of airway inflammation and is driven by complex neuroimmune regulation involving submucosal glands and goblet cells. Although studies have focused on mast cell degranulation as a critical driver of nasal secretion, the role of goblet cells in this process is relatively under-researched. In allergic airway inflammation, goblet cells exhibit metaplasia and hypersecretion. However, allergen exposure does not directly trigger goblet cell degranulation, raising questions regarding the underlying mechanisms of these reactions. The activation of enteric neurons promotes goblet cell degranulation by stimulating the calcitonin gene-related peptide (CGRP)-receptor active modification protein-1 (RAMP1) axis. Meanwhile, airway goblet cells express various neuropeptide receptors, and their activation by neuropeptides such as substance P and CGRP induces mucus secretion, exacerbating allergic rhinitis-associated hypersecretion. Thus, although previously less recognised, the neuron-goblet cell signalling axis plays a critical role in allergic rhinitis mucus secretion. This review highlights current research on the neuroimmune mechanisms underlying goblet cell metaplasia and degranulation, focusing on allergic rhinitis, so as to guide clinical treatment strategies.

Integrated Multi-Omics Analysis Reveals Mountain-Cultivated Ginseng Ameliorates Cold-Stimulated Steroid-Resistant Asthma by Regulating Interactions among Microbiota, Genes, and Metabolites

Steroid-resistant asthma (SRA), resisting glucocorticoids such as dexamethasone (DEX), is a bottleneck in the treatment of asthma. It is characterized by a predominantly neutrophilic inflammatory subtype and is prone to developing into severe refractory asthma and fatal asthma. Currently, there is a lack of universally effective treatments for SRA. Moreover, since cold stimulation does increase the risk of asthma development and exacerbate asthma symptoms, the treatment of cold-stimulated SRA (CSRA) will face greater challenges. To find effective new methods to ameliorate CSRA, this study established a CSRA mouse model of allergic airway inflammation mimicking human asthma for the first time and evaluated the alleviating effects of 80% ethanol extract of mountain-cultivated ginseng (MCG) based on multi-omics analysis. The results indicate that cold stimulation indeed exacerbated the SRA-related symptoms in mice; the DEX individual treatment did not show a satisfactory effect; while the combination treatment of DEX and MCG could dose-dependently significantly enhance the lung function; reduce neutrophil aggregation; decrease the levels of LPS, IFN-γ, IL-1β, CXCL8, and IL-17; increase the level of IL-10; alleviate the inflammatory infiltration; and decrease the mucus secretion and the expression of MUC5AC. Moreover, the combination of DEX and high-dose (200 mg/kg) MCG could significantly increase the levels of tight junction proteins (TJs), regulate the disordered intestinal flora, increase the content of short-chain fatty acids (SCFAs), and regulate the abnormal gene profile and metabolic profile. Multi-omics integrated analysis showed that 7 gut microbes, 34 genes, 6 metabolites, and the involved 15 metabolic/signaling pathways were closely related to the pharmacological effects of combination therapy. In conclusion, integrated multi-omics profiling highlighted the benefits of MCG for CSRA mice by modulating the interactions of microbiota, genes, and metabolites. MCG shows great potential as a functional food in the adjuvant treatment of CSRA.

Does behavior mediate the effect of weather on SARS-CoV-2 transmission? evidence from cell-phone data

There is growing evidence that weather alters SARS-CoV-2 transmission, but it remains unclear what drives the phenomenon. One prevailing hypothesis is that people spend more time indoors in cooler weather, leading to increased spread of SARS-CoV-2 related to time spent in confined spaces and close contact with others. However, the evidence in support of that hypothesis is limited and, at times, conflicting. We use a mediation framework, and combine daily weather, COVID-19 hospital surveillance, cellphone-based mobility data and building footprints to estimate the relationship between daily indoor and outdoor weather conditions, mobility, and COVID-19 hospitalizations. We quantify the direct health impacts of weather on COVID-19 hospitalizations and the indirect effects of weather via time spent indoors away-from-home on COVID-19 hospitalizations within five Colorado counties between March 4th 2020 and January 31st 2021. We also evaluated the evidence for seasonal effect modification by comparing the results of all-season (using season as a covariate) to season-stratified models. Four weather conditions were associated with both time spent indoors away-from-home and 12-day lagged COVID-19 hospital admissions in one or more season: high minimum temperature (all-season), low maximum temperature (spring), low minimum absolute humidity (winter), and high solar radiation (all-season & winter). In our mediation analyses, we found evidence that changes in 12-day lagged hospital admissions were primarily via the direct effects of weather conditions, rather than via indirect effects by which weather changes time spent indoors away-from-home. Our findings do not support the hypothesis that weather impacted SARS-CoV-2 transmission via changes in mobility patterns during the first year of the pandemic. Rather, weather appears to have impacted SARS-CoV-2 transmission primarily via mechanisms other than human movement. We recommend further analysis of this phenomenon to determine whether these findings generalize to current SARS-CoV-2 transmission dynamics, as well as other seasonal respiratory pathogens.

Does behavior mediate the effect of weather on SARS-CoV-2 transmission? Evidence from cell-phone data

Background

There is growing evidence that weather alters SARS-CoV-2 transmission, but it remains unclear what drives the phenomenon. One prevailing hypothesis is that people spend more time indoors in cooler weather, leading to increased spread of SARS-CoV-2 related to time spent in confined spaces and close contact with others. However, the evidence in support of that hypothesis is limited and, at times, conflicting.

Objectives

We aim to evaluate the extent to which weather impacts COVID-19 via time spent away-from-home in indoor spaces, as compared to a direct effect of weather on COVID-19 hospitalization, independent of mobility.

Methods

We use a mediation framework, and combine daily weather, COVID-19 hospital surveillance, cellphone-based mobility data and building footprints to estimate the relationship between daily indoor and outdoor weather conditions, mobility, and COVID-19 hospitalizations. We quantify the direct health impacts of weather on COVID-19 hospitalizations and the indirect effects of weather via time spent indoors away-from-home on COVID-19 hospitalizations within five Colorado counties between March 4th 2020 and January 31st 2021.

Results

We found evidence that changes in 12-day lagged hospital admissions were primarily via the direct effects of weather conditions, rather than via indirect effects by which weather changes time spent indoors away-from-home. Sensitivity analyses evaluating time at home as a mediator were consistent with these conclusions.

Discussion

Our findings do not support the hypothesis that weather impacted SARS-CoV-2 transmission via changes in mobility patterns during the first year of the pandemic. Rather, weather appears to have impacted SARS-CoV-2 transmission primarily via mechanisms other than human movement. We recommend further analysis of this phenomenon to determine whether these findings generalize to current SARS-CoV-2 transmission dynamics and other seasonal respiratory pathogens.

Lung transcriptomics reveals the underlying mechanism by which aerobic training enhances pulmonary function in chronic obstructive pulmonary disease

BACKGROUND

Aerobic training is the primary method of rehabilitation for improving respiratory function in patients with chronic obstructive pulmonary disease (COPD) in remission. However, the mechanism underlying this improvement is not yet fully understood. The use of transcriptomics in rehabilitation medicine offers a promising strategy for uncovering the ways in which exercise training improves respiratory dysfunction in COPD patients. In this study, lung tissue was analyzed using transcriptomics to investigate the relationship between exercise and lung changes.

METHODS

Mice were exposed to cigarette smoke for 24 weeks, followed by nine weeks of moderate-intensity treadmill exercise, with a control group for comparison. Pulmonary function and structure were assessed at the end of the intervention and RNA sequencing was performed on the lung tissue.

RESULTS

Exercise training was found to improve airway resistance and lung ventilation indices in individuals exposed to cigarette smoke. However, the effect of this treatment on damaged alveoli was weak. The pair-to-pair comparison revealed numerous differentially expressed genes, that were closely linked to inflammation and metabolism.

CONCLUSIONS

Further research is necessary to confirm the cause-and-effect relationship between the identified biomarkers and the improvement in pulmonary function, as this was not examined in the present study.

Temperature influences commensal-pathogen dynamics in a nasal epithelial cell co-culture model

Chronic rhinosinusitis (CRS) is an inflammatory disease of the paranasal sinuses, and microbial dysbiosis associated with CRS is thought to be a key driver of host inflammation that contributes to disease progression. Staphylococcus aureus is a common upper respiratory tract (URT) pathobiont associated with higher carriage rates in CRS populations, where S. aureus-secreted toxins can be identified in CRS tissues. Although many genera of bacteria colonize the URT, few account for the majority of sequencing reads. These include S. aureus and several species belonging to the genus Corynebacterium, including Corynebacterium propinquum and Corynebacterium pseudodiphtheriticum, which are observed at high relative abundance in the healthy URT. Studies have examined bacterial interactions between major microbionts of the URT and S. aureus, but few have done so in the context of a healthy versus diseased URT environment. Here, we examine the role of temperature in commensal, pathogen, and epithelial dynamics using an air-liquid interface cell culture model mimicking the nasal epithelial environment. Healthy URT temperatures change from the nares to the nasopharynx and are increased during disease. Temperatures representative of the healthy URT increase persistence and aggregate formation of commensal C. propinquum and C. pseudodiphtheriticum, reduce S. aureus growth, and lower epithelial cytotoxicity compared to higher temperatures correlating with the diseased CRS sinus. Dual-species colonization revealed species-specific interactions between Corynebacterium species and S. aureus dependent on temperature. Our findings suggest URT mucosal temperature plays a significant role in mediating polymicrobial and host-bacterial interactions that may exacerbate microbial dysbiosis in chronic URT diseases.IMPORTANCEChronic rhinosinusitis is a complex inflammatory disease with a significant healthcare burden. Although presence of S. aureus and microbial dysbiosis are considered mediators of inflammation in CRS, no studies have examined the influence of temperature on S. aureus interactions with the nasal epithelium and the dominant genus of the healthy URT, Corynebacterium. Interactions between Corynebacterium species and S. aureus have been documented in several studies, but none to date have examined how environmental changes in the URT may alter their interactions with the epithelium or each other. This study utilizes a polarized epithelial cell culture model at air-liquid interface to study the colonization and spatial dynamics of S. aureus and clinical isolates of Corynebacterium from people with CRS to characterize the role temperature has in single- and dual-species dynamics on the nasal epithelium.

Loss of TRPM8 Exacerbate Herpes Simplex Keratitis Infection in Mice by Promoting the Infiltration of CD11b+ Ly6G+ Cells and Increasing the Viral Load in the Cornea

Purpose

To reveal the role of transient receptor potential cation subfamily M member 8 (TRPM8) channels in herpes simplex keratitis (HSK).

Methods

HSK models were established using TRPM8 knockout (TRPM8-/-) mice and their wild-type (WT) littermates. The infected corneas were graded and harvested to evaluate the mRNA levels of inflammatory factors through quantitative real-time polymerase chain reaction (RT-PCR), as well as the infiltration of inflammatory cells through immunofluorescence staining and flow cytometry. Viral titers were determined by plaque assay and absolute quantitative method. RNA-sequencing was conducted to elucidate the transcriptome of corneal epithelium in response to TRPM8 knockout after infection. The anti-inflammatory effect of TRPM8 agonist menthol was documented via subconjunctival administration.

Results

Compared to their wild-type counterparts, TRPM8-deficient mice exhibited exacerbated infection symptoms and thicker corneas in HSK models. Infection in TRPM8-deficient mice resulted in significant lymphocyte infiltration, primarily consisting of Ly6G+ CD11b+ cells. Additionally, TRPM8-deficient mice displayed increased levels of corneal viral titers after infection, along with decreased expression of interferon-stimulated genes (ISGs). Subconjunctival administration of menthol effectively alleviated infection-induced symptoms and Ly6G+ CD11b+ cell infiltration in herpes simplex virus type 1 (HSV-1)-treated mice.

Conclusions

TRPM8 promoted host resistance to HSV-1 infection by suppressing the accumulation of Ly6G+ CD11b+ cells and virus replication. These findings suggest that targeting TRPM8 could be valuable for therapeutic interventions against HSV-1 infections.

Burden of chronic obstructive pulmonary disease attributable to non-optimal temperature from 1990 to 2019: a systematic analysis from the Global Burden of Disease Study 2019

Chronic obstructive pulmonary disease (COPD) has been the third leading cause of death worldwide. As the traditional risk factors (like smoking and ambient air pollution) on the burden of COPD being well characterized, the burden of COPD due to non-optimal temperature has been widely concerned. In this study, we extracted the relevant burden data of COPD attributable to non-optimal temperature from GBD 2019 and adopted estimated annual percent changes, Gaussian process regression (GPR), and age-period-cohort model to evaluate the spatiotemporal patterns, relationships with socio-demographic level, and the independent effects of age, period and cohort from 1990 to 2019. In brief, the global COPD burden attributable to non-optimal temperatures showed declining trends but was still more severe in the elderly, males, Asia, and regions with low socio-demographic index (SDI). And cold had a greater burden than heat. The inverted U-shape is expected for the relationship between SDI and the burden of COPD caused by non-optimal temperatures according to the GPR model, with the inflection point around SDI 0.45. Besides, the improvements were observed in period and cohort effects but were relatively limited in low and low-middle SDI regions. Public health managers should execute more targeted programs to lessen this burden predominantly among lower SDI countries.

Cold spells linked with respiratory disease hospitalization, length of hospital stay, and hospital expenses: Exploring cumulative and harvesting effects

BACKGROUND

Previous studies have revealed the relationship between cold spells and morbidity and mortality due to respiratory diseases, while the detrimental effects of cold spells on the length of hospital stay and hospitalization expenses remain largely unknown.

METHODS

We collected hospitalization data for respiratory diseases in 11 cities of Shanxi, China during 2017-2019. In each case, exposure to meteorological variables and air pollution was estimated by the bilinear interpolation approach and inverse distance weighting method, respectively, and then averaged at the city level. Cold spells were defined as the daily mean temperature below the 10^th, 7.5^th, or 5^th percentiles for at least 2 to 5 consecutive days. We applied distributed lag non-linear models combined with generalized additive models to assess cumulative effects and harvesting effects.

RESULTS

There were significant associations between cold spells and hospital admissions, length of hospital stay, and hospital expenses for respiratory diseases. Compared with the non-cold spell period, the overall (lag 0-21) cumulative risk of hospitalization for total respiratory diseases was 1.232 (95 % CI: 1.090, 1.394) on cold spell days, and the increased length of hospital stay and hospitalization expenses were 112.793 (95 % CI: 10.755, 214.830) days and 127.568 (95 % CI: 40.513, 214.624) thousand Chinese yuan. The overall cumulative risks of cold spells on total respiratory diseases and pneumonia were statistically significant. We further observed harvesting effects in the associations between cold spells and hospital admission, length of hospital stay, and hospitalization expenses for respiratory diseases.

CONCLUSIONS

Cumulative cold-spell exposure for up to three weeks is associated with hospitalization, length of hospital stay, and hospital expenses for respiratory diseases. The observed harmful effects of cold spells on respiratory diseases can be partly attributable to harvesting effects.

Relationship between meteorological and environmental factors and acute exacerbation for pediatric bronchial asthma: Comparative study before and after COVID-19 in Suzhou

Objective

Climate and environmental change is a well-known factor causing bronchial asthma in children. After the outbreak of coronavirus disease (COVID-19), climate and environmental changes have occurred. The present study investigated the relationship between climate changes (meteorological and environmental factors) and the number of hospitalizations for pediatric bronchial asthma in Suzhou before and after the COVID-19 pandemic.

Methods

From 2017 to 2021, data on daily inpatients diagnosed with bronchial asthma at Children's Hospital of Soochow University were collected. Suzhou Meteorological and Environmental Protection Bureau provided daily meteorological and environmental data. To assess the relationship between bronchial asthma-related hospitalizations and meteorological and environmental factors, partial correlation and multiple stepwise regression analyses were used. To estimate the effects of meteorological and environmental variables on the development of bronchial asthma in children, the autoregressive integrated moving average (ARIMA) model was used.

Results

After the COVID-19 outbreak, both the rate of acute exacerbation of bronchial asthma and the infection rate of pathogenic respiratory syncytial virus decreased, whereas the proportion of school-aged children and the infection rate of human rhinovirus increased. After the pandemic, the incidence of an acute asthma attack was negatively correlated with monthly mean temperature and positively correlated with PM2.5. Stepwise regression analysis showed that monthly mean temperature and O3 were independent covariates (risk factors) for the rate of acute asthma exacerbations. The ARIMA (1, 0, 0) (0, 0, 0) 12 model can be used to predict temperature changes associated with bronchial asthma.

Conclusion

Meteorological and environmental factors are related to bronchial asthma development in children. The influence of meteorological and environmental factors on bronchial asthma may be helpful in predicting the incidence and attack rates.

Nebulized Menthol Impairs Mucociliary Clearance via TRPM8 and MUC5AC/MUC5B in Primary Airway Epithelial Cells

Flavorings enhance the palatability of e-cigarettes (e-cigs), with menthol remaining a popular choice among e-cig users. Menthol flavor remains one of the only flavors approved by the United States FDA for use in commercially available, pod-based e-cigs. However, the safety of inhaled menthol at the high concentrations used in e-cigs remains unclear. Here, we tested the effects of menthol on parameters of mucociliary clearance (MCC) in air-liquid interface (ALI) cultures of primary airway epithelial cells. ALI cultures treated with basolateral menthol (1 mM) showed a significant decrease in ciliary beat frequency (CBF) and airway surface liquid (ASL) volumes after 24 h. Menthol nebulized onto the surface of ALI cultures similarly reduced CBF and increased mucus concentrations, resulting in decreased rates of mucociliary transport. Nebulized menthol further increased the expression of mucin 5AC (MUC5AC) and mRNA expression of the inflammatory cytokines IL1B and TNFA. Menthol activated TRPM8, and the effects of menthol on MCC and inflammation could be blocked by a specific TRPM8 antagonist. These data provide further evidence that menthol at the concentrations used in e-cigs could cause harm to the airways.

Impact of cold spells on COPD mortality in Jiangsu Province, China

Ambient cold is associated with substantial population attributable fraction of mortality in China, and respiratory health is vulnerable to cold exposure. This study aimed to examine the effect of cold spells on risk of deaths from chronic obstructive pulmonary disease (COPD). We collected daily data on deaths from COPD and climatic factors from 1 January 2016 to 31 December 2019 in 13 cities of Jiangsu Province, China. We used a quasi-Poisson generalized linear model coupled with a distributed lag non-linear model to quantify the association between risk of COPD deaths and exposure to cold spells (defined as 2 or more consecutive days with mean temperature ≤ 5^th percentile of daily mean temperature distribution in cold months). Stratification analyses by age, sex, education, and occupation were undertaken to identify vulnerable subgroups. The results suggested that exposure to cold spells was associated with a higher risk of COPD deaths in Lianyungang (relative risk (RR): 1.70; 95% confidence interval (CI): 1.31, 2.21), Nanjing (RR: 1.54; 95% CI: 1.16, 2.04), Nantong (RR: 1.97; 95% CI: 1.68, 2.31), Suzhou (RR: 1.97; 95% CI: 1.55, 2.50), Suqian (RR: 1.68; 95% CI: 1.23, 2.29), Taizhou (RR: 1.70; 95% CI: 1.32, 2.19), Wuxi (RR: 1.99; 95% CI: 1.53, 2.60), Xuzhou (RR: 1.71; 95% CI: 1.01, 2.90), Yancheng (RR: 1.78; 95% CI: 1.53, 2.06), Yangzhou (RR: 2.78; 95% CI: 2.06, 3.76), and Zhenjiang (RR: 1.79; 95% CI: 1.26, 2.55). All subgroups seemed to be vulnerable to the effect of cold spells. The recommendation of this study is that individuals with pre-existing COPD, regardless of age, sex, education, or occupation, should be made aware of the health risk posed by cold spells and should be encouraged to take cold adaptation actions before cold season arrives. The main limitation of this study is that it is subject to ecological fallacy.

Mathematical modeling in the health risk assessment of air pollution-related disease burden in China: A review

This review paper covers an overview of air pollution-related disease burden in China and a literature review on the previous studies which have recently adopted a mathematical modeling approach to demonstrate the relative risk (RR) of air pollution-related disease burden. The associations between air pollution and disease burden have been explored in the previous studies. Therefore, it is necessary to quantify the impact of long-term exposure to ambient air pollution by using a suitable mathematical model. The most common way of estimating the health risk attributable to air pollution exposure in a population is by employing a concentration-response function, which is often based on the estimation of a RR model. As most of the regions in China are experiencing rapid urbanization and industrialization, the resulting high ambient air pollution is influencing more residents, which also increases the disease burden in the population. The existing RR models, including the integrated exposure-response (IER) model and the global exposure mortality model (GEMM), are critically reviewed to provide an understanding of the current status of mathematical modeling in the air pollution-related health risk assessment. The performances of different RR models in the mortality estimation of disease are also studied and compared in this paper. Furthermore, the limitations of the existing RR models are pointed out and discussed. Consequently, there is a need to develop a more suitable RR model to accurately estimate the disease burden attributable to air pollution in China, which contributes to one of the key steps in the health risk assessment. By using an updated RR model in the health risk assessment, the estimated mortality risk due to the impacts of environment such as air pollution and seasonal temperature variation could provide a more realistic and reliable information regarding the mortality data of the region, which would help the regional and national policymakers for intensifying their efforts on the improvement of air quality and the management of air pollution-related disease burden.

Associations between indoor relative humidity and global COVID-19 outcomes

Globally, the spread and severity of COVID-19 have been distinctly non-uniform. Seasonality was suggested as a contributor to regional variability, but the relationship between weather and COVID-19 remains unclear and the focus of attention has been on outdoor conditions. Because humans spend most of their time indoors and because most transmission occurs indoors, we here, instead, investigate the hypothesis that indoor climate-particularly indoor relative humidity (RH)-may be the more relevant modulator of outbreaks. To study this association, we combined population-based COVID-19 statistics and meteorological measurements from 121 countries. We rigorously processed epidemiological data to reduce bias, then developed and experimentally validated a computational workflow to estimate indoor conditions based on outdoor weather data and standard indoor comfort conditions. Our comprehensive analysis shows robust and systematic relationships between regional outbreaks and indoor RH. In particular, we found intermediate RH (40-60%) to be robustly associated with better COVID-19 outbreak outcomes (versus RH < 40% or >60%). Together, these results suggest that indoor conditions, particularly indoor RH, modulate the spread and severity of COVID-19 outbreaks.

Asthma mortality attributable to ambient temperatures: A case-crossover study in China

BACKGROUND

Whether ambient temperature exposure contributes to death from asthma remains unknown to date. We therefore conducted a case-crossover study in China to quantitatively evaluate the association and burden of ambient temperature exposure on asthma mortality.

METHODS

Using data from the National Mortality Surveillance System in China, we conducted a time-stratified case-crossover study of 15 888 individuals who lived in Hubei and Jiangsu province, China and died from asthma as the underlying cause in 2015-2019. Individual-level exposures to air temperature and apparent temperature on the date of death and 21 days prior were assessed based on each subject's residential address. Distributed lag nonlinear models based on conditional logistic regression were used to quantify exposure-response associations and calculate fraction and number of deaths attributable to non-optimum ambient temperatures.

RESULTS

We observed a reverse J-shaped association between air temperature and risk of asthma mortality, with a minimum mortality temperature of 21.3 °C. Non-optimum ambient temperature is responsible for substantial excess mortality from asthma. In total, 26.3% of asthma mortality were attributable to non-optimum temperatures, with moderate cold, moderate hot, extreme cold and extreme hot responsible for 21.7%, 2.4%, 2.1% and 0.9% of asthma mortality, respectively. The total attributable fraction and number was significantly higher among adults aged less than 80 years in hot temperature.

CONCLUSIONS

Exposure to non-optimum ambient temperature, especially moderate cold temperature, was responsible for substantial excess mortality from asthma. These findings have important implications for planning of public-health interventions to minimize the adverse respiratory damage from non-optimum ambient temperature.

Dynamic Changes in Colonic Structure and Protein Expression Suggest Regulatory Mechanisms of Colonic Barrier Function in Torpor-Arousal Cycles of the Daurian Ground Squirrel

Background: Both pathological conditions and hibernation can affect the barrier function of small intestine mucosa. However, the effect of hibernation on the barrier function of colonic mucosa remains unclear. Methods: We investigated morphological changes in colonic mucosa, the concentrations of specific proteins and molecules, and the enzymatic activity of diamine oxidase (DAO), in serum and colonic tissue; the expression of tight junction proteins and mucin, and the changes in inflammatory, farnesoid X receptor (FXR)–small heterodimer partner (SHP), and apoptosis-related molecules that could play a role in gut permeability changes in Daurian ground squirrels in summer active (SA), late torpor (LT), and interbout arousal (IBA) periods. Results: The results show that hibernation reduced the thickness of the colonic mucosa and the depth of the crypt, decreased the number of goblet cells (GCs), and damaged the structure of some microvilli. The concentrations of proteins and molecules, and the enzymatic activity of DAO, were all increased in the serum and colon, and the localization of tight junction proteins and mucin in the colonic mucosa were altered (compensatory response). Although the ground squirrels ate during the interbout arousal period, the changes remained similar to the response to torpor. Inflammation, apoptosis–anti-apoptosis, and FXR–SHP signaling may be involved in the possible changes in intestinal gut permeability during the torpor–arousal cycle in Daurian ground squirrels. In addition, periodic interbout arousal may play an inflammation-correcting role during the long hibernation season of Daurian ground squirrels.

Association of children wheezing diseases with meteorological and environmental factors in Suzhou, China

Wheezing diseases are one of the major chronic respiratory diseases in children. To explore the effects of meteorological and environmental factors on the prevalence of children wheezing diseases, clinical data of children hospitalized with wheezing diseases in Suzhou, China from 2013 to 2017 were collected. Meteorological and environmental factors from 2013 to 2017 were obtained from the local Meteorological Bureau and Environmental Protection Bureau. Relationships between wheezing diseases and meteorological and environmental factors were evaluated using Pearson's correlation and multivariate regression analysis. An autoregressive integrated moving average (ARIMA) model was used to estimate the effects of meteorological and environmental variables on children wheezing diseases. Children wheezing diseases were frequently presented in infants less than 12 months old (1897/2655, 58.28%), and the hospitalization rate was highest in winter (1024/3255, 31.46%). In pathogen-positive specimens, the top three pathogens were respiratory syncytial virus (21.35%), human rhinovirus (16.28%) and mycoplasma pneumoniae (10.47%). The seasonality of wheezing children number showed a distinctive winter peak. Children wheezing diseases were negatively correlated with average temperature (P < 0.001, r =  - 0.598). The ARIMA (1,0,0)(0,0,0)₁₂ model could be used to predict temperature changes associated wheezing diseases. Meteorological and environmental factors were associated with the number of hospitalized children with wheezing diseases and can be used as early warning indicators for the occurrence of wheezing diseases and prevalence of virus.

The impact of personal and outdoor temperature exposure during cold and warm seasons on lung function and respiratory symptoms in COPD

Rationale

Chronic obstructive pulmonary disease (COPD) patients often report aggravated symptoms due to heat and cold, but few studies have formally evaluated this.

Methodology

We followed 30 Boston-based former smokers with COPD for four non-consecutive 30-day periods over 12 months. Personal and outdoor temperature exposure were measured using portable and Boston-area outdoor stationary monitors. Participants recorded daily morning lung function measurements as well as any worsening breathing (breathlessness, chest tightness, wheeze) and bronchitis symptoms (cough, sputum colour and amount) compared to baseline. Using linear and generalised linear mixed-effects models, we assessed associations between personal and outdoor temperature exposure (1-3-day moving averages) and lung function and symptoms, adjusting for humidity, smoking pack-years and demographics. We also stratified by warm and cold season.

Results

Participants were on average 71.1±8.4 years old, with 54.4±30.7 pack-years of smoking. Each 5°C increase in personal temperature exposure was associated with 1.85 (95% CI 0.99-3.48) higher odds of worsening breathing symptoms. In the warm season, each 5°C increase in personal and outdoor temperature exposure was associated with 3.20 (95% CI 1.05-9.72) and 2.22 (95% CI 1.41-3.48) higher odds of worsening breathing symptoms, respectively. Each 5°C decrease in outdoor temperature was associated with 1.25 (95% CI 1.04-1.51) higher odds of worsening bronchitis symptoms. There were no associations between temperature and lung function.

Conclusions

Our findings suggest that higher temperature, including outdoor exposure during the warm season and personal temperature exposure year-round, may worsen dyspnoea, while colder outdoor temperature may trigger cough and phlegm symptoms among COPD patients.

The role of Cold-Inducible RNA-binding protein in respiratory diseases

Cold‐inducible RNA‐binding protein (CIRP) is a stress‐response protein that is expressed in various types of cells and acts as an RNA chaperone, modifying the stability of its targeted mRNA. Intracellular CIRP could also be released into extracellular space and once released, extracellular CIRP (eCIRP) acts as a damage‐associated molecular pattern (DAMP) to induce and amplify inflammation. Recent studies have found that eCIRP could promote acute lung injury (ALI) via activation of macrophages, neutrophils, pneumocytes and lung vascular endothelial cells in context of sepsis, haemorrhagic shock, intestinal ischemia/reperfusion injury and severe acute pancreatitis. In addition, CIRP is also highly expressed in the bronchial epithelial cells and its expression is upregulated in the bronchial epithelial cells of patients with chronic obstructive pulmonary diseases (COPD) and rat models with chronic bronchitis. CIRP is a key contributing factor in the cold‐induced exacerbation of COPD by promoting the expression of inflammatory genes and hypersecretion of airway mucus in the bronchial epithelial cells. Besides, CIRP is also involved in regulating pulmonary fibrosis, as eCIRP could directly activate and induce an inflammatory phenotype in pulmonary fibroblast. This review summarizes the findings of CIRP investigation in respiratory diseases and the underlying molecular mechanisms.

Cold-inducible RNA-binding protein migrates from the nucleus to the cytoplasm under cold stress in normal human bronchial epithelial cells via TRPM8-mediated mechanism

Background

Cold-inducible RNA-binding protein (CIRP or hnRNP A18) is a multifunctional stress-responsive protein. Our previous study demonstrated that cold stress increased CIRP expression and migrated from the nucleus to the cytoplasm in airway epithelial cells. However, the mechanism through which CIRP migrates from the nucleus to the cytoplasm upon cold stress remains unknown.

Methods

The expression of CIRP in the bronchial epithelium was examined using immunofluorescence, real-time polymerase chain reaction (RT-PCR), and Western blotting. The expression of inflammatory factors interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-α (TNF-α) were detected by ELISA and RT-PCR. Transient receptor potential melastatin 8 (TRPM8) receptor function was characterized by Ca²⁺ imaging.

Results

Cold stress upregulated the expression of CIRP, inflammatory factors and promoted the translocation of CIRP from the nucleus to the cytoplasm in normal human bronchial epithelial (NHBE) cells. Cold stress activated the TRPM8/(Ca²⁺)/PKCα/glycogen synthase kinase 3β (GSK3β) signaling cascade, and that inhibition of this signaling pathway attenuated the migration of CIRP from the nucleus to cytoplasm but did not decrease its overexpression induced by cold stress. Knocked down CIRP expression or blocked CIRP migration between the nucleus and cytoplasm significantly decreased inflammatory factor expression.

Conclusions

These results indicate that cold stress leads to the migration of CIRP from the nucleus to the cytoplasm with alteration of expression, which are involved in the expression of inflammatory factors (IL-1β, IL-6, IL-8 and TNF-α) induced by cold air, through TRPM8/Ca²⁺/PKCα/GSK3β signaling cascade.

Increased hospital admissions for asthma from short-term exposure to cold spells in Beijing, China

BACKGROUND

There is a paucity of studies investigating extreme cold events and asthma exacerbations. This study examined whether an association exists between cold spells and daily hospital admissions for asthma in Beijing, China from 2012 to 2016.

METHODS

Daily hospital admissions for asthma, meteorological variables and air quality data were collected during 2012-2016 in Beijing. A cold spell was defined as a period of at least two consecutive days with the daily mean temperature below or at the 5th percentile (-7 °C) in cold seasons (November to March) during the study period. We applied a time-series design using quasi-Poisson regression combined with a distributed lag model to estimate the risk of asthma hospital admissions associated with cold spells. Stratified analyses by gender and age groups were conducted to identify the potential susceptible subpopulations to cold spells. We also explored the effect modification by air quality by dividing the daily air quality index (AQI) into two levels (high and low) based on the median value.

RESULTS

Cold spells increased the risk of asthma hospital admissions, with the maximum cumulative relative risk (CRR) over three weeks (Lag0-21) in the total population. The highest single-day relative risk (RR) was found on the days of cold spells (Lag0) with the RR = 1.059 (95% CI: 1.008-1.113), and the CRR at Lag0-21 was 1.333 (95% CI: 1.049-1.693). Across different gender and age groups, younger people (<65 years) were more sensitive to cold spells. No significant effect modification by AQI was detected.

CONCLUSION

Short-term exposure to cold spells is associated with an increased risk of hospital admissions for asthma in Beijing. During the cold spells, younger people aged <65 years were at particular risk for asthma exacerbations. Our results suggest that extreme cold events have a significant impact on asthma.

The Impact of Air Pollutants and Meteorological Factors on Chronic Obstructive Pulmonary Disease Exacerbations: A Nationwide Study

RATIONALE Chronic obstructive lung disease (COPD) is a chronic progressive disease. Although smoking is the most important risk factor, 30% of COPD patients are never smokers, and environmental agents are also influential. The effects of air pollutants and meteorological factors on COPD exacerbations have not been studied extensively. OBJECTIVE We aimed to investigate the air pollutants and meteorological factors that impact the incidence of COPD exacerbations. METHODS We obtained clinical data of COPD exacerbation cases from The National Health Insurance Service (NHIS) and merged it with 24-hour average values of air pollutants and meteorological factors from national databases. Patients who reside in eight metropolitan cities, where observatory stations are densely located, were selected for analysis. RESULTS In 1,404,505 COPD patients between 2013 and 2018, 15,282 COPD exacerbations leading to hospitalization or emergency room visits were identified. Among the various air pollutants and meteorological factors, particulate matter (PM)2.5, PM10, NO2, SO2, CO, O3, average temperature and diurnal temperature range (DTR) were associated with COPD exacerbations. GAM model analysis with cubic splines showed an inverted U-shaped relationship with PM2.5, PM10, CO, NO2, SO2, O3, DTR and humidity, while it displayed a U-shaped pattern with the average temperature. Distinct patterns were found from 2015-2016 to 2017-2018. CONCLUSIONS PM2.5, PM10, CO, NO2, O3, SO2, average temperature, humidity, and DTR affected the incidence of COPD exacerbations in various patterns, up to 10 lag days.

Tackling nasal symptoms in athletes: Moving towards personalized medicine

Adequate nasal breathing is indispensable for athletes, and nasal symptoms have been shown to interfere with their subjective feeling of comfortable breathing and quality of life. Nasal symptoms are caused by either structural abnormalities or mucosal pathology. Structural pathologies are managed differently from mucosal disease, and therefore, adequate diagnosis is of utmost importance in athletes in order to choose the correct treatment option for the individual. Literature suggests that nasal symptoms are more prevalent in athletes compared to the general population and certain sports environments might even trigger the development of symptoms. Given the high demands of respiratory function in athletes, insight into triggering factors is of high importance for disease prevention. Also, it has been suggested that athletes are more neglectful to their symptoms and hence remain undertreated, meaning that special attention should be paid to education of athletes and their caregivers. This review aims at giving an overview of nasal physiology in exercise as well as the possible types of nasal pathology. Additionally, diagnostic and treatment options are discussed and we focus on unmet needs for the management and prevention of these symptoms in athletes within the concept of precision medicine.

TRPM8 Channels: Advances in Structural Studies and Pharmacological Modulation

The transient receptor potential melastatin subtype 8 (TRPM8) is a cold sensor in humans, activated by low temperatures (>10, <28 °C), but also a polymodal ion channel, stimulated by voltage, pressure, cooling compounds (menthol, icilin), and hyperosmolarity. An increased number of experimental results indicate the implication of TRPM8 channels in cold thermal transduction and pain detection, transmission, and maintenance in different tissues and organs. These channels also have a repercussion on different kinds of life-threatening tumors and other pathologies, which include urinary and respiratory tract dysfunctions, dry eye disease, and obesity. This compendium firstly covers newly described papers on the expression of TRPM8 channels and their correlation with pathological states. An overview on the structural knowledge, after cryo-electron microscopy success in solving different TRPM8 structures, as well as some insights obtained from mutagenesis studies, will follow. Most recently described families of TRPM8 modulators are also covered, along with a section of molecules that have reached clinical trials. To finalize, authors provide an outline of the potential prospects in the TRPM8 field.

Emerging role of air pollution and meteorological parameters in COVID-19

Exposure to air pollutants has been associated with respiratory viral infections. Epidemiological studies have shown that air pollution exposure is related to increased cases of SARS-COV-2 infection and COVID-19-associated mortality. In addition, the changes of meteorological parameters have also been implicated in the occurrence and development of COVID-19. However, the molecular mechanisms by which pollutant exposure and changes of meteorological parameters affects COVID-19 remains unknown. This review summarizes the biology of COVID-19 and the route of viral transmission, and elaborates on the relationship between air pollution and climate indicators and COVID-19. Finally, we envisaged the potential roles of air pollution and meteorological parameters in COVID-19.

TRP channels in airway sensory nerves

Transient Receptor Potential (TRP) channels expressed in specific subsets of airway sensory nerves function as transducers and integrators of a diverse range of sensory inputs including chemical, mechanical and thermal signals. These TRP sensors can detect inhaled irritants as well as endogenously released chemical substances. They play an important role in generating the afferent activity carried by these sensory nerves and regulating the centrally mediated pulmonary defense reflexes. Increasing evidence reported in recent investigations has revealed important involvements of several TRP channels (TRPA1, TRPV1, TRPV4 and TRPM8) in the manifestation of various symptoms and pathogenesis of certain acute and chronic airway diseases. This mini-review focuses primarily on these recent findings of the responses of these TRP sensors to the biological stresses emerging under the pathophysiological conditions of the lung and airways.

Rapid changes in mucociliary transport in the tracheal epithelium caused by unconditioned room air or nebulized hypertonic saline and mannitol are not determined by frequency of beating cilia

Background

Inspired air is heated and humidified in the nose before it reaches lower airways. This mechanism is bypassed during tracheostomy, directly exposing the airways to colder and drier air from the environment, known to negatively affect mucociliary transport; however, little is known about how quickly mucociliary transport deteriorates. This study determines the short-term effect of flowing room air and nebulized hypertonic saline and mannitol on mucociliary transport in the trachea. In an ovine perfused in vitro tracheal model (N = 9) the epithelium was exposed to 25 L/min of flow, heated to lamb body temperature (38 °C) and fully saturated with water vapor as the control, followed by either room air (22 °C and 50% relative humidity) or nebulized solutions of NaCl 7% and mannitol 20% up to 1 min for a short duration, until mucociliary transport had visually changed. Mucus transport velocity (MTV) and cilia beat frequency (CBF) were continuously measured with video-microscopy.

Results

Exposing the tracheal epithelium to air heated to body temperature and fully humidified had stable MTV 9.5 ± 1.1 mm/min and CBF 13.4 ± 0.6 Hz. When exposed to flow of room air, MTV slowed down to 0.1 ± 0.1 mm/min in 2.0 ± 0.4 s followed by a decrease in CBF to 6.7 ± 1.9 Hz, after 2.3 ± 0.8 s. Both MTV and CBF recovered to their initial state when heated and humidified air-flow was re-introduced. Exposing the tracheal epithelium to nebulized hypertonic saline and nebulized mannitol for 1 min increased MTV without a subsequent increase in CBF.

Conclusions

This study demonstrates mucociliary transport can deteriorate within seconds of exposing the tracheal epithelium to flowing room air and increase rapidly when exposed to nebulized hypertonic solutions. The reduction in MTV precedes slowing of CBF with room air and MTV increases without a subsequent increase in CBF during the nebulization. Their relationship is non-linear and a minimum CBF of approximately 6 Hz is required for MTV > 0, while MTV can reach 10.9 mm/min without CBF increasing. Clinically these findings indicate a potential rapid detrimental effect of breathing with non-humidified air via bypassed upper airways and the short-term effects of nebulized osmotic agents that increase MTV.

Effect of TRPM8 and TRPA1 Polymorphisms on COPD Predisposition and Lung Function in COPD Patients

Certain transient receptor potential (TRP) channels including TRPM8 and TRPA1 are widely expressed in the respiratory tract and have been shown to be the receptors of cigarette smoke and particulate matter-the main causative factors of chronic obstructive pulmonary disease (COPD). The aim of the study was to investigate the effect of TRPM8 and TRPA1 polymorphisms on COPD predisposition and lung function in COPD patients. The study enrolled 143 COPD patients and 104 smokers with post-bronchodilator forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) > 70%. Lung function was measured by spirometry. TRPM8 and TRPA1 polymorphisms were genotyped by LATE-PCR. None of the polymorphisms significantly influenced COPD predisposition after correction for covariates and multiple testing. Among COPD patients, the TT genotype of TRPA1 rs7819749 was significantly associated with higher degree of bronchial obstruction. In addition, we established that carriers of the C allele of TRPM8 rs11562975 more commonly had post-bronchodilator FEV1 < 60% (OR 3.2, 95%CI (1.14-8.94), p = 0.03) and revealed the effect of TRPA1 rs959976 and TRPM8 rs17865682 on bronchodilator response in COPD. Thus, the obtained results suggest possible involvement of TRPM8 and TRPA1 in COPD pathogenesis, indicating the necessity to further investigate their functional role in this pathology.

Effect of extreme hot and cold weather on cause-specific hospitalizations in Sweden: A time series analysis

Considering that several meteorological variables can contribute to weather vulnerability, the estimation of their synergetic effects on health is particularly useful. The spatial synoptic classification (SSC) has been used in biometeorological applications to estimate the effect of the entire suite of weather conditions on human morbidity and mortality. In this study, we assessed the relationships between extremely hot and dry (dry tropical plus, DT+) and hot and moist (moist tropical plus, MT+) weather types in summer and extremely cold and dry (dry polar plus, DP+) and cold and moist (moist polar, MP+) weather types in winter and cardiovascular and respiratory hospitalizations by age and sex. Time-series quasi-Poisson regression with distributed lags was used to assess the relationship between oppressive weather types and daily hospitalizations over 14 subsequent days in the extended summer (May to August) and 28 subsequent days during the extended winter (November to March) over 24 years in 4 Swedish locations from 1991 to 2014. In summer, exposure to hot weather types appeared to reduce cardiovascular hospitalizations while increased the risk of hospitalizations for respiratory diseases, mainly related to MT+. In winter, the effect of cold weather on both cause-specific hospitalizations was small; however, MP+ was related to a delayed increase in cardiovascular hospitalizations, whilst MP+ and DP + increased the risk of hospitalizations due to respiratory diseases. This study provides useful information for the staff of hospitals and elderly care centers who can help to implement protective measures for patients and residents. Also, our results could be helpful for vulnerable people who can adopt protective measures to reduce health risks.

Effect of Ambient Temperature on Daily Nebulized Asthma Hospital Visits in a Tropical City of Dhaka, Bangladesh

The acute effect of temperature on asthma morbidity in Bangladesh is not well understood. As climate varies extensively in different parts of the world, the relation between temperature and asthma might also differ. We investigated the association between temperature and asthma-related hospital visits in the tropical city of Dhaka. We analyzed information from a total of 5989 asthma patients who received ambulatory care in the form of nebulized medication at the National Asthma Center in Mohakhali, Dhaka from February to November 2013. A time-stratified case-crossover study was conducted to estimate the effect of daily temperature, with consideration of delayed effects and possible confounders such as relative humidity and political strikes. An inverse association was observed between temperature and the number of hospital visits. The effect was delayed for approximately a week. A degree centigrade decrease in mean temperature (averaged across lags 0-6) was associated with an increase of approximately 4.5% (95% CI 1.5, 7.5) in all asthma visits. The association was evident in adult males but marginal in elderly males. A positive association (lag 0) was observed among adult females, whereas no association was observed among children. Strikes significantly modified the effect among the elderly. Findings suggest temperature declines affect asthma outcomes in a warm climate, and this effect can be delayed and vary by sex and age group.

Variability in tracheal mucociliary transport is not controlled by beating cilia in lambs in vivo during ventilation with humidified and nonhumidified air

Mucociliary transport in the respiratory epithelium depends on beating of cilia to move a mucus layer containing trapped inhaled particles toward the mouth. Little is known about the relationship between cilia beat frequency (CBF) and mucus transport velocity (MTV) in vivo under normal physiological conditions and when inspired air is dry or not fully humidified. This study was designed to use video-microscopy to simultaneously measure CBF and MTV in the tracheal epithelium through an implanted optical window in mechanically ventilated lambs. The inspired air in 6 animals was heated to body temperature and fully saturated with water for 4 hours as a baseline. In another series of experiments, 5 lambs were ventilated with air at different temperatures and humidities and the mucosal surface temperature was monitored with infrared macro-imaging. In the baseline experiments, during ventilation with fully humidified air at body temperature, CBF remained constant, mean 13.9 ± 1.6 Hz but MTV varied considerably between 0.1 and 26.1 mm/min with mean 11.0 ± 3.9 mm/min, resulting in a maximum mucus displacement of 34.2 µm/cilia beat. Fully humidified air at body temperature prevented fluctuations in the surface temperature during breathing indicating a thermodynamic balance in the airways. When lambs were ventilated with dryer air, the mucosal surface temperature and MTV dropped without a significant change in CBF. When inspired air was dry, mainly latent heat (92%) was transferred to air in the trachea, reducing the surface temperature by 5 °C. Reduced humidity of the inspired air lowered the surface temperature and reduced MTV in the epithelium during ventilation.

Short-term effects of cold spells on hospitalisations for acute exacerbation of chronic obstructive pulmonary disease: a time-series study in Beijing, China

OBJECTIVES

Our work aimed at exploring the relationship between cold spells and acute exacerbation of chronic obstructive pulmonary disease (AECOPD) hospitalisations in Beijing, China, and assessing the moderating effects of the intensities and the durations of cold spells, as well as identifying the vulnerable.

DESIGN

A time-series study.

SETTING

We obtained time-series data of AECOPD hospitalisations, meteorological variables and air quality index in Beijing, China during 2012-2016.

PARTICIPANTS

All AECOPD hospitalisations among permanent residents in Beijing, China during the cold seasons (November-March) of 2012-2016 were included (n=84 571).

PRIMARY AND SECONDARY OUTCOME MEASURES

A quasi-Poisson regression with a distributed lag model was fitted to investigate the short-term effects of cold spells on AECOPD hospitalisations by comparing the counts of AECOPD admissions during cold spell days with those during non-cold spell days.

RESULTS

Cold spells under different definitions were associated with increased risk of AECOPD hospitalisations, with the maximum cumulative relative risk (CRR) over 3 weeks (lag0-21). The cumulative effects at lag0-21 increased with the intensities and the durations of cold spells. Under the optimal definition, the most significant single-day relative risk (RR) was found on the days of cold spells (lag0) with an RR of 1.042 (95% CI 1.013 to 1.072), and the CRR at lag0-21 was 1.394 (95% CI 1.193 to 1.630). The elderly (aged ≥65) were more vulnerable to the effects of cold spells on AECOPD hospitalisations.

CONCLUSION

Cold spells are associated with increased AECOPD hospitalisations in Beijing, with the cumulative effects increased with intensities and durations. The elderly are at particular risk of AECOPD hospitalisations triggered by cold spells.

[Menthol enhances interleukin-13-induced synthesis and secretion of mucin 5AC in human bronchial epithelial cells]

OBJECTIVE

To investigate the effect of interleukin (IL) -13 combined with cold stimulation on synthesis and secretion of mucin (MUC) 5AC in human bronchial epithelial cell line 16HBE and explore the role of transient receptor potential 8 (TRPM8) and anti-apoptotic factor B-cell lymphoblast-2 (Bcl-2) in this process.

METHODS

16HBE cells were stimulated with 10 ng/mL IL-13, 1 mmol/L menthol, or both (1 mmol/L menthol was added after 6 days of IL-13 stimulation), and the changes in the expression of MUC5AC, intracellular Ca²⁺ concentration and Bcl-2 expression were evaluated. The effects of ABT-263 (a Bcl-2 inhibitor) and BCTC (a TRPM8 ion channel inhibitor), alone or in combination, on MUC5AC expression in the cells were tested, and the changes in intracellular Ca²⁺ and Bcl-2 expression following BCTC treatment were observed. The cell viability was assessed using CCK-8 assay, the mRNA expressions of MUC5AC and Bcl-2 were detected with real-time quantitative PCR, the level of MUC5AC in the culture medium was measured with ELISA, and the intracellular Ca²⁺ fluorescence intensity was determined with flow cytometry.

RESULTS

The mRNA and protein expressions of MUC5AC increased significantly in 16HBE cells following stimulation with IL-13, menthol, and both (P < 0.05), and were the highest in the combined treatment group with its peak level occurred at 24 h (P < 0.01). The intracellular Ca²⁺ fluorescence intensity and Bcl-2 mRNA expression were also increased in 16HBE cells after the stimulations (P < 0.05), and the increments were the most obvious in the combined treatment group (P < 0.01). Treatment with BCTC significantly lowered intracellular Ca²⁺ fluorescence intensity and the expressions of Bcl-2 and MUC5AC mRNA and protein in the cells stimulated with menthol or with both IL-13 and menthol (P < 0.05), but caused no significant changes in IL-13-stimulated cells (P > 0.05). Treatment with ABT-263 significantly lowered the mRNA and protein expressions of MUC5AC in the cells stimulated with IL-13 and menthol either alone or in combination (P < 0.05).

CONCLUSIONS

Menthol combined with IL-13 produces a synergistic effect to promote the synthesis and secretion of MUC5AC in 16HBE cells possibly by activating TRPM8 receptor to upregulate the expression of Bcl-2.

TRPM8 channels: A review of distribution and clinical role

Ion channels are important therapeutic targets due to their plethoric involvement in physiological and pathological consequences. The transient receptor potential cation channel subfamily M member 8 (TRPM8) is a nonselective cation channel that controls Ca²⁺ homeostasis. It has been proposed to be the predominant thermoreceptor for cellular and behavioral responses to cold stimuli in the transient receptor potential (TRP) channel subfamilies and exploited so far to reach the clinical-stage of drug development. TRPM8 channels can be found in multiple organs and tissues, regulating several important processes such as cell proliferation, migration and apoptosis, inflammatory reactions, immunomodulatory effects, pain, and vascular muscle tension. The related disorders have been expanded to new fields ranging from cancer and migraine to dry eye disease, pruritus, irritable bowel syndrome (IBS), and chronic cough. This review is aimed to summarize the distribution of TRPM8 and disorders related to it from a clinical perspective, so as to broaden the scope of knowledge of researchers to conduct more studies on this subject.

Seasonality of Respiratory Viral Infections

The seasonal cycle of respiratory viral diseases has been widely recognized for thousands of years, as annual epidemics of the common cold and influenza disease hit the human population like clockwork in the winter season in temperate regions. Moreover, epidemics caused by viruses such as severe acute respiratory syndrome coronavirus (SARS-CoV) and the newly emerging SARS-CoV-2 occur during the winter months. The mechanisms underlying the seasonal nature of respiratory viral infections have been examined and debated for many years. The two major contributing factors are the changes in environmental parameters and human behavior. Studies have revealed the effect of temperature and humidity on respiratory virus stability and transmission rates. More recent research highlights the importance of the environmental factors, especially temperature and humidity, in modulating host intrinsic, innate, and adaptive immune responses to viral infections in the respiratory tract. Here we review evidence of how outdoor and indoor climates are linked to the seasonality of viral respiratory infections. We further discuss determinants of host response in the seasonality of respiratory viruses by highlighting recent studies in the field.

Effect of seasonal variance on intestinal epithelial barriers and the associated innate immune response of the small intestine of the Chinese soft-shelled turtles

It is conceivable that pathological conditions can cause intestinal barrier disruption and innate immune dysfunction. However, very limited information has been reported on the effect of seasonal variance on intestinal barriers and innate immunity. The present study was designed to investigate the seasonal variance in intestinal epithelial barriers and the associated innate immune response of turtle intestines during hibernation and nonhibernation periods. Goblet cells (GCs) demonstrated dynamic actions of the mucosal barrier with strong Muc2 protein expression during hibernation. However, weak Muc2 expression during nonhibernation was confirmed by immunohistochemistry, immunofluorescence and immunoblotting. Furthermore, light and transmission electron microscopy revealed that the hypertrophy of GCs resulted in the hypersecretion of mucus granules (MGs) and created a well-developed mucosal layer during hibernation. The absorptive cells (ACs), forming a physical barrier of tight junctions, and desmosomes were firmly anchored during hibernation. Conversely, during nonhibernation, the integrity of tight junctions, adherence junctions and desmosomes was noticeable expanded, causing increased paracellular permeability. As further confirmation, there was strong zonula occluden-1 (ZO-1) and connexins 43 (Cx43) protein expression during hibernation and weak ZO-1 and Cx43 expression during nonhibernation. Moreover, the expression level of the innate immune response proteins Toll-like receptors 2 and 4 (TLR2 and 4) were enhanced during hibernation and were reduced during nonhibernation. These results provide rich information about the seasonal fluctuations that interrupt intestinal epithelial barriers and innate immune response, which might be essential for protection and intestinal homeostasis.

Effects of Ambient Temperature on Acute Exacerbations of Chronic Obstructive Pulmonary Disease: Results from a Time-Series Analysis of 143318 Hospitalizations

Purpose

To evaluate the associations between acute exacerbations of chronic obstructive pulmonary disease (AECOPD) hospitalizations and daily mean temperature (Tmean) as well as daily apparent temperature (AT), and to explore the practical values of these two indices in policymaking and patient education.

Methods

Daily AECOPD hospitalizations and Meteorological data in Beijing were obtained between 2013 and 2016. Distributed lag non-linear model was adopted to investigate the association between daily ambient temperature and AECOPD hospitalizations. The cumulative effects of cold/hot temperature were abstracted. For the extreme and moderate low-temperature effect estimates, we, respectively, computed the RR of AECOPD hospitalizations at the 1st and 10th percentiles of temperature in comparison with that at the 25th percentile of temperature. For the extreme and moderate high temperature effect estimates, we, respectively, computed the RR of AECOPD hospitalizations at the 99th and 90th percentiles of temperature in comparison with that at the 75th percentile of temperature.

Results

During the study period, 143, 318 AECOPD hospitalizations were collected. A reverse J-shape relationship was found between temperature and AECOPD hospitalizations. When comparing the effect of Tmean, higher RRs were associated with increases in AT on AECOPD hospitalizations but a lower value of Akaike’s Information Criterion for quasi-Poisson (Q-AIC). The RR of extremely low temperature of Tmean and AT were 1.55 (95% CI: 1.21,2.00) and 2.08 (95% CI: 1.44,3.01), respectively. Moderate low temperature also had an adverse impact on AECOPD hospitalizations. No associations were found between high temperature and AECOPD risk. We found the females and those aged <65 years to be more susceptible to temperature change.

Conclusion

Lower temperature is associated with a higher risk for AECOPD hospitalizations. Ambient temperature is probably a better predictor in terms of quantifying risk than mean temperature when studying temperature impact on health.

Ca2+ Channel Toolkit in Neuroendocrine Tumors

Neuroendocrine tumors (NET) constitute a heterogeneous group of malignancies with various clinical presentations and growth rates but a common origin in neuroendocrine cells located all over the body. NET are a relatively low-frequency disease mostly represented by gastroenteropancreatic (GEP) and bronchopulmonary tumors (pNET); on the other hand, an increasing frequency and prevalence have been associated with NET. Despite great efforts in recent years, the management of NET is still a critical unmet need due to the lack of knowledge of the biology of the disease, the lack of adequate biomarkers, late presentation, the relative insensitivity of imaging modalities, and a paucity of predictably effective treatment options. In this context Ca2+ signals, being pivotal molecular devices in sensing and integrating signals from the microenvironment, are emerging to be particularly relevant in cancer, where they mediate interactions between tumor cells and the tumor microenvironment to drive different aspects of neoplastic progression (e.g., cell proliferation and survival, cell invasiveness, and proangiogenetic programs). Indeed, ion channels represent good potential pharmacological targets due to their location on the plasma membrane, where they can be easily accessed by drugs. The present review aims to provide a critical and up-to-date overview of NET development integrating Ca2+ signal involvement. In this perspective, we first give an introduction to NET and Ca2+ channels and then describe the different families of Ca2+ channels implicated in NET, i.e., ionotropic receptors, voltage-dependent Ca2+ channels, and transient receptor potential channels, as well as intracellular Ca2+ channels and their signaling molecules.

Activation of Transient Receptor Potential Melastatin Family Member 8 (TRPM8) Receptors Induces Proinflammatory Cytokine Expressions in Bronchial Epithelial Cells

Purpose

Cold air is a major environmental factor that exacerbates asthma. Transient receptor potential melastatin family member 8 (TRPM8) is a cold-sensing channel expressed in the airway epithelium. However, its role in airway inflammation remains unknown. We investigated the role of TRPM8 in innate immune responses in bronchial epithelial cells and asthmatic subjects.

Methods

The TRPM8 mRNA and protein expression on BEAS2B human bronchial epithelial cells was examined by real-time polymerase chain reaction (PCR), immunofluorescence staining and western blotting. Additionally, interleukin (IL)-4, IL-6, IL-8, IL-13, IL-25 and thymic stromal lymphopoietin (TSLP) levels before and after menthol, dexamethasone and N-(4-tert-butylphenyl)-4-(3-chloropyridin-2-yl) piperazine-1-carboxamide (BCTC) treatments were measured via real-time PCR. TRPM8 protein levels in the supernatants of induced sputum from asthmatic subjects and normal control subjects were measured using enzyme-linked immunosorbent assay, and mRNA levels in sputum cell lysates were measured using real-time PCR.

Results

Treatment with up to 2 mM menthol dose-dependently increased TRPM8 mRNA and protein in BEAS2B cells compared to untreated cells (P < 0.001) and concomitantly increased IL-25 and TSLP mRNA (P < 0.05), but not IL-33 mRNA. BCTC (10 μM) significantly abolished menthol-induced up-regulation of TRPM8 mRNA and protein and IL-25 and TSLP mRNA (P < 0.01). TRPM8 protein levels were higher in the supernatants of induced sputum from asthmatic subjects (n = 107) than in those from healthy controls (n = 19) (P < 0.001), and IL-25, TSLP and IL-33 mRNA levels were concomitantly increased (P < 0.001). Additionally, TRPM8 mRNA levels correlated strongly with those of IL-25 and TSLP (P < 0.001), and TRPM8 protein levels were significantly higher in bronchodilator-responsive asthmatic subjects than in nonresponders.

Conclusions

TRPM8 may be involved in the airway epithelial cell innate immune response and a molecular target for the treatment of asthma.

[Role of mammalian target of rapamycin activation in menthol-induced expressions of airway inflammation-related factors in human bronchial epithelial cells in vitro]

OBJECTIVE

To investigate the role of mammalian target of rapamycin (mTOR) activation in menthol-induced expression of airway inflammation- related factors in human bronchial epithelial cells and explore its mechanism.

METHODS

Cultured human bronchial epithelial cells (BEAS-2B) were divided into normal control group, menthol group, rapamycin group, and menthol+rapamycin group with corresponding treatments. The cell viability was measured with CCK-8 method. The mRNA levels of transient receptor potential melastatin 8 (TRPM8), tumor necrosis factor (TNF)-α and interleukin (IL)-1β were detected by RT-PCR, and the protein expressions of phosphorylated mTOR (p-mTOR), TRPM8, TNF-α and IL-1β were determined using Western blotting. The intracellular Ca²⁺ fluorescence intensity was measured by flow cytometry.

RESULTS

Compared with the normal control cells, menthol- treated cells showed significantly increased TNF-α, IL-1β, and p-mTOR expression and elevated intracellular Ca²⁺ concentration (P < 0.05), and the rapamycin-treated cells exhibited significantly decreased p-mTOR expression (P < 0.05). No significant difference was found in TNF-α, IL-1β or intracellular Ca²⁺ concentration between the normal control and rapamycin-treated cells (P>0.05). Compared with the menthol-treated cells, the cells treated with both menthol and rapamycin showed significantly decreased TNF- α, IL-1β, and p-mTOR expression and obviously lowered intracellular Ca²⁺ concentration (P < 0.05).

CONCLUSIONS

Menthol promotes the expressions of airway inflammationrelated factors IL-1β and TNF-α possibly by activating mTOR to cause the increase of intracellular Ca²⁺ concentration.

Impact of weather conditions on childhood admission for wheezy chest and bronchial asthma

Background: Climate change represents a possible threat to patients with bronchial asthma. The purpose of this study was to investigate any association between specific meteorological conditions and the rate of hospital admission for bronchial asthma and wheezy chest. Methods: A retrospective study was conducted to observe the effects of changes in some meteorological variables on children aged 1-13 years with bronchial asthma and wheezy chest. Data were obtained from hospital registries for the study period involving all patients admitted with the diagnosis of wheezy chest and bronchial asthma. The meteorological data were obtained from the Iraqi World Meteorological Organization and Seismology and consisted of the mean monthly values of humidity, rain, temperature, dust, wind, and thunderstorms. The correlation between the mean monthly admission for bronchial asthma and changes in weather variables were investigated. Results: There were 1043 admissions for asthma or wheezy chest (7.76%). Out of all asthma cases, 75% (n=783) were 1-5 years, while 25% (n=260) were 6-13 years. Male patients predominate 67.8%, with a male to female ratio of 2:1. Hospital admissions for asthma and wheezy chest showed a seasonal variation especially for younger children. Higher monthly admission rates were associated with high relative humidity, rain, increase in wind speed, and lower temperature, whereas rising dust and thunderstorms did not show notable effects on children's admission for asthma. Conclusion: The findings suggested that changes in weather conditions, especially high relative humidity and cold weather, may trigger asthma attacks especially in younger children, and thus protective measures are recommended for at risk children.

Effects of Meteorological Factors on Hospitalizations in Adult Patients with Asthma: A Systematic Review

Background

Environmental factors such as weather variables contribute to asthma exacerbation. The impact of meteorological factors on asthma-related hospital admissions (HAs) or emergency department visits (EDVs) has been assessed in the literature. We conducted a systematic review to establish a conclusion of whether these findings from the literature are consistent and generalizable or if they vary significantly by certain subgroups.

Objective

This study aims to review the effect of meteorological variables on asthma HAs and EDVs in adults, to identify knowledge gaps and to highlight future research priorities.

Method

A systematic search was conducted in electronic databases such as PubMed, Embase, and CINAHL. All studies published in English were screened and included if they met the eligibility criteria. Two independent reviewers assessed the quality of the studies and extracted the data. The available evidence was summarized and presented using a harvest plot.

Results

Our initial search returned a total of 3887 articles. After screening titles, abstracts, and full texts, 16 studies were included. Thirty-one percent of the included studies (5/16) found that temperature was the only factor associated with asthma hospitalization or EDVs. Six studies (37%) found that both temperature and relative humidity were associated with HAs. Four studies (25%) identified thunderstorms as a possible factor associated with asthma hospitalization in adults.

Conclusion

Our review suggests that HAs and EDVs due to asthma are associated with many meteorological factors. Among the articles included in this review, changing temperature is the most commonly studied variable. We did not find studies that measured barometric pressure, weather phenomena, or the effect of tornados. To develop effective strategies to protect subjects at risk, further studies are required.

Transient Receptor Potential Melastatin 8 (TRPM8)-Based Mechanisms Underlie Both the Cold Temperature-Induced Inflammatory Reactions and the Synergistic Effect of Cigarette Smoke in Human Bronchial Epithelial (16HBE) Cells

Transient receptor potential melastatin 8 (TRPM8) is a major receptor of cold environment. Recently, we found that cigarette smoke extract (CSE) upregulated TRPM8 mRNA and protein expression in bronchial tissues that made them more sensitive to cold stimuli. In our present study, we found that cold temperature (18°C)-induced activation of TRPM8 in 16HBE (human bronchial epithelial) cells facilitated Ca²⁺ influx and subsequently led to the increased expression of interleukin (IL)-6, IL-8, and tumor necrosis factor (TNF)-α via the upregulation of p-extracellular signal-regulated kinase (ERK) and the activation of NF-κB. In addition, 16HBE cells that co-stimulated with 18°C and CSE were used to explore the synergistic effect of CSE on cold temperature-induced inflammatory cytokine production as well as the possible involved signaling pathway. RT-PCR and western blot analysis revealed that CSE upregulated TRPM8 mRNA and protein level in 16HBE cells. Ca²⁺ imaging, western blot, and luciferase assay showed more robust increase in intracellular Ca²⁺ and promoted phosphorylated ERK, P38, and NF-κB activity, respectively, in 16HBE cells co-stimulated with CSE and cold temperature, and such alteration was attenuated by TRPM8 short hairpin RNA (shRNA) transfection and BCTC pretreatment. Furthermore, enhanced levels of IL-6, IL-8, and TNF-α showed by enzyme-linked immunosorbent assay (ELISA) were reduced by specific inhibitors of ERK and NF-κB. Collectively, our results suggest that mitogen-activated protein kinase (MAPK)/NF-κB signaling is involved in TRPM8-mediated cold temperature-induced inflammatory cytokine expression. In addition, CSE synergistically amplifies cold temperature-induced inflammatory factors release via upregulating TRPM8 expression and enhancing MAPK/NF-κB signaling pathway.

[Clinical and inflammatory phenotypic features of asthmatic patients sensitive to cold stimulation]

OBJECTIVE

To explore the clinical symptoms, lung function and airway inflammation phenotype characteristics of asthmatic patients who are sensitive to cold stimulation.

METHODS

Eighty patients with newly diagnosed bronchial asthma or with mild to moderate acute exacerbation of previously diagnosed bronchial asthma but without regular treatment were selected. According to whether cold air stimulation could induce respiratory symptoms such as cough and wheeze, the patients were divided into cold-insensitive group (45 cases) and cold-sensitive group (35 cases). All the patients were treated with inhaled corticosteroid (ICS), long-acting β2 receptor agonist (LABA; salmeterol xinafoate and fluticasone propionate powder for inhalation, 50 μg/250 μg, twice daily) and montelukast sodium tablets (10 mg, once daily); short-acting β2 receptor agonist (SABA) and/or systemic glucocorticoid (prednisone acetate tablets, 10 mg, once daily; or injection of methylprednisolone sodium succinate, 40 mg) were given if necessary. Asthma Control Test (ACT) score before treatment and at 3 months of treatment was used to assess the clinical symptoms such as cough and wheeze; spirometry was performed to determine lung function impairment and recovery. Blood and induced sputum cell counts were examined to determine the characteristics of airway inflammation.

RESULTS

The two groups were comparable for age, gender, BMI, proportion of smokers and allergic rhinitis before treatment. The cold-sensitive patients experienced significantly more frequent acute exacerbations than the cold-insensitive patient within 1 year before the visit (P < 0.05), but the use of SABA and glucocorticoid for symptom control during the treatment did not differ significantly between the two groups (P > 0.05). The ACT scores of the cold-sensitive group were significantly lower than those of the cold-insensitive group both before and after the treatment (P < 0.01). Compared with the cold-insensitive patients, the cold-sensitive patients had more obvious impairment of FEV1/FVC% and FEV1%pred before treatment (P < 0.01), and also showed poorer recovery after treatment (P < 0.05). The percentages of eosinophils in blood and induced sputum samples did not differ significantly between the two groups either before and after the treatment, but the percentage of neutrophils was significantly higher in the cold-sensitive group (P < 0.01). In the induced sputum samples collected before treatment, the cell populations consisted mainly of eosinophilic subtype (60%) and neutrophilic subtype (20%) in the cold-insensitive group; in the cold-sensitive patients, the sputum neutrophilic subtype cells increased significantly to 42.86% (P=0.03) and the eosinophilic subtype cells were lowered to 31.43% (P=0.01).

CONCLUSIONS

The cold-sensitive asthmatic patients experience frequent recurrent and/or aggravated symptoms and have obvious lung function impairment. Different from that in patients with classic asthma, the airway inflammatory phenotype in these patients is characterized by the domination by neutrophilic subtype.

MARCKS phosphorylation and amylase release in GLP-1-stimulated acini isolated from rat pancreas

Little is known about the effects of glucagon-like peptide 1 (GLP-1) on the pancreatic exocrine gland. In the gland, secretagogues induce amylase release. That signal transduction is evoked mainly by an increase in intracellular Ca2+ levels and activation of protein kinase C (PKC). We previously demonstrated that myristoylated alanine-rich C kinase substrate (MARCKS), a PKC substrate, is involved in pancreatic amylase release. Here, we studied the effects of GLP-1 on MARCKS phosphorylation and amylase release in rat pancreatic acini. GLP-1 induced amylase release and MARCKS phosphorylation in isolated pancreatic acini. Inhibitors of cAMP-dependent protein kinase (PKA) suppressed those effects. Furthermore, a MARCKS-related peptide inhibited the GLP-1-induced amylase release. These findings suggest that GLP-1 induces amylase release through MARCKS phosphorylation via activation of PKA in isolated pancreatic acini.

Menthol Cigarette Smoke Induces More Severe Lung Inflammation Than Non-menthol Cigarette Smoke Does in Mice With Subchronic Exposure - Role of TRPM8

In smokers with chronic obstructive pulmonary disease, more severe lung inflammation is associated with menthol cigarette smoking compared to non-menthol cigarette smoking. However, the mechanisms remain unclear. Menthol is an activator of transient receptor potential melastatin-8 (TRPM8), which is also sensitive to reactive oxygen species (ROS). Our recent in vitro study demonstrated that the extracts of menthol cigarette smoke (M-CS) can induce greater ROS-sensitive, TRPM8-mediated, mitogen-activated protein kinase (MAPK)-dependent inflammatory responses in lung epithelial cells than the extracts of non-menthol cigarette smoke (Non-M-CS) can. In this study, we tested the hypothesis that M-CS can induce more severe lung inflammation than Non-M-CS can via the additional action of menthol in M-CS on epithelial and lung TRPM8 in mice. Compared with Non-M-CS exposure, subchronic M-CS exposure for 7 days up-regulated the epithelial and lung expression of TRPM8, induced more vigorous activation of epithelial and lung MAPKs, and caused more severe lung inflammation. The MAPK activation was evidenced by the increased expression of phosphor-extracellular signal-regulated and phosphor-c-Jun N-terminal kinases. The lung inflammation was evidenced by pathohistological findings and increases in several inflammatory indices. Moreover, treatment with a TRPM8 antagonist (N-(3-aminopropyl)-2-{[(3-methylphenyl)methyl]oxy}-N-(2-thienylmethyl)benzamide; AMTB) greatly suppressed the MAPK activation and lung inflammation induced by Non-M-CS and M-CS, and the residual responses to these two types of CS did not differ. Conversely, the levels of biomarkers of acute CS exposure (20 min), including carboxyhemoglobin and cotinine (a nicotine metabolite) in blood plasma, and superoxide and hydrogen peroxide (two major types of ROS) in bronchoalveolar lavage fluid, did not show significant differences in the mice with Non-M-CS and M-CS exposure. We concluded that M-CS could induce greater TRPM8-mediated activation of MAPKs and lung inflammation than Non-M-CS could in mice with subchronic exposure. The augmented inflammatory effects of M-CS are unlikely due to a larger total amount of CS inhaled, but may be caused by an additional stimulation of epithelial and lung TRPM8 by menthol in M-CS. A common stimulant (presumably ROS) generated by both CS types may also stimulate TRPM8, activate MAPKs, and induce lung inflammation because treatment with AMTB could reduce these responses to Non-M-CS.

Cold Stimuli Facilitate Inflammatory Responses Through Transient Receptor Potential Melastatin 8 (TRPM8) in Primary Airway Epithelial Cells of Asthmatic Mice

Bronchial asthma is a chronic inflammatory airway disease that can be aggravated by cold air. However, its mechanism remains largely unknown. As a thermo-sensing cation channel, transient receptor potential melastatin 8 (TRPM8) can be activated by cold stimuli (8-22 °C) and cooling agents. Whereas TRPM8 activation leads to enhanced expression of inflammatory cytokines and mucus hypersecretion in human bronchial epithelial cell lines, no previous study has examined its role in regulating the cold-induced inflammatory responses and its mechanism in asthmatic airway epithelium. Airway epithelial cells were isolated from asthma model mice and exposed to low temperature (18 °C). The TRPM8 overexpression plasmid and siRNA lentivirus were transfected to up- or downregulate the TRPM8 level. The expression of mRNAs of inflammatory cytokines was tested using real-time reverse transcription-polymerase chain reaction (RT-PCR). The activities of phosphorylated protein kinase C (PKC) and phosphorylated inhibitor of nuclear factor kappa B (IκB) were measured using the immunofluorescence assay. The expression of mRNAs of inflammatory cytokines [interleukin (IL)-1β, IL-4, IL-6, IL-8, IL-10, IL-13, granulocyte macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor (TNF)-α] increased significantly under cold conditions, which was boosted after TRPM8 overexpression and augmented further in the presence of PKC inhibitor, calphostin C. However, the downregulation of TRPM8 and nuclear factor kappa B (NF-κB) impaired the transcription of these cytokine genes. In addition, the phosphorylated PKC and phosphorylated IκB were activated by cold stimuli. Moreover, the expression of phosphorylated IκB protein improved in the presence of TRPM8, while disruption with the TRPM8 gene or TRPM8 antagonist prohibited the activation of IκB. Cold air could induce inflammatory responses through the TRPM8-mediated PKC/NF-κB signal pathway in primary airway epithelial cells of asthmatic mice.

COPD rat model is more susceptible to cold stress and PM2.5 exposure and the underlying mechanism

The purpose of this study is to verify the hypothesis that chronic obstructive pulmonary disease (COPD) model rat is more susceptible to cold stress and fine particulate matter (PM_2.5) exposure than the healthy rat, and explore the related mechanism. COPD rat model, established with cigarette smoke and lipopolysaccharide intratracheal instillation, were exposed to cold stress (0 °C) and PM_2.5 (0, 3.2, 12.8 mg/ml). After that, the levels of superoxide dismutase, inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-α), monocyte chemotactic protein 1 (MCP-1) and angiotensin Ⅱ (Ang-Ⅱ) in lung were measured, as well as the expression levels of lung 8-hydroxy-2-deoxyguanosine (8-OHdG), nuclear factor kappa B (NF-κB), heme-oxygenase-1 (HO-1) and nuclear factor erythroid-2-related factor 2 (Nrf2). There were significant positive relationships between PM_2.5 and lung level of iNOS, TNF-α, MCP-1 and Ang-Ⅱ, lung function and pathologic damage in COPD rats. The HO-1, NF-κB and 8-OHdG were found highly expressed in COPD rat lung, particularly at the higher PM_2.5 dose of cold stress groups, while Nrf2 was found declined. Thus, COPD rats may be more susceptible to cold stress and PM_2.5 exposure. Cold stress may aggravate PM_2.5-induced toxic effects in the lung of COPD rats through increasing Ang-Ⅱ/NF-κB signaling pathway and suppressing Nrf2 signaling pathway.

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.