Development and systematic oxidative stress of a rat model of chronic bronchitis and emphysema induced by biomass smoke

Advanced models for respiratory disease and drug studies

The global burden of respiratory diseases is enormous, with many millions of people suffering and dying prematurely every year. The global COVID-19 pandemic witnessed recently, along with increased air pollution and wildfire events, increases the urgency of identifying the most effective therapeutic measures to combat these diseases even further. Despite increasing expenditure and extensive collaborative efforts to identify and develop the most effective and safe treatments, the failure rates of drugs evaluated in human clinical trials are high. To reverse these trends and minimize the cost of drug development, ineffective drug candidates must be eliminated as early as possible by employing new, efficient, and accurate preclinical screening approaches. Animal models have been the mainstay of pulmonary research as they recapitulate the complex physiological processes, Multiorgan interplay, disease phenotypes of disease, and the pharmacokinetic behavior of drugs. Recently, the use of advanced culture technologies such as organoids and lung-on-a-chip models has gained increasing attention because of their potential to reproduce human diseased states and physiology, with clinically relevant responses to drugs and toxins. This review provides an overview of different animal models for studying respiratory diseases and evaluating drugs. We also highlight recent progress in cell culture technologies to advance integrated models and discuss current challenges and present future perspectives.

Spirometry parameter alterations due to exposure to indoor air pollutants in rural homes in Bogotá, Colombia

The aim of this study was to determine the association between the concentrations of intradomiciliary PM_2.5, CO, and BC and alterations in respiratory function parameters in a population living in rural dwellings in Bogotá, Colombia. For this cross-sectional study, people were recruited from the rural areas of the localities of Usme and Sumapaz in Bogotá. In total, 68 participants were recruited by means of nonrandom sampling. Indoor air monitoring of PM_2.5, BC, and CO was carried out. Additionally, evaluations of pulmonary function were performed using spirometry. The variables of pulmonary function were included in a multiple linear regression by successive steps and adjusted by the main variables described as modifiers of spirometry parameters, which are age, height, sex, disability, and a history of tobacco use. Assumptions of multicollinearity and the randomization of variances in the residuals were evaluated. Negative associations were found between spirometry parameters and the concentrations of indoor air pollutants. For FEV1/FVC and theoretical FEV1, there was a statistically significant association with the concentration of carbon monoxide (p = 0.003 and 0.019, respectively). The environmental concentrations were higher in homes where biomass was used for cooking, but these differences were statistically significant only for BC and CO (p = 0.008 and 0.03, respectively). The concentrations of carbon monoxide in rural homes were associated with alterations in respiratory function parameters.

Household solid fuel use and peak expiratory flow in middle-aged and older adults in China: A large cohort study (2011-2015)

Indoor air pollution caused by solid fuel use in cooking and heating in China is common. The relationship between household solid fuel use and peak expiratory flow (PEF) in middle-aged and older adults in China has not been clarified. The aim of this study was to assess the relationship between long-term household solid fuel use (clean for both cooking and heating, solid for either cooking or heating, and solid for both cooking and heating) and PEF changes in middle-aged and older adults using a nationally representative prospective cohort. Covariance analysis was used to compare PEF changes in different indoor air pollution exposure groups. Separate analysis of cooking and heating as well as sub-group analyses by age, sex and smoking status were conducted, linear mixed growth model analysis was used to evaluate the association between cooking fuel type and PEF. A total of 6818 participants were enrolled in the cohort analysis. Results revealed that solid fuel use in cooking and heating separately or conjointly were associated with reduced PEF (solid fuel use in cooking: least square mean [LSM] = 19.9, 95% confidence interval [CI]: 11.5-28.2, P = 0.03; solid fuel use in heating: LSM = 19.4, 95% CI:11.2-27.5, P = 0.04; both solid fuel use: LSM = 17.6, 95% CI: 9.3-25.9, P for trend <0.0001), especially in participants aged >65 years (LSM = -9.22, 95% CI: 27.9-69.52, P for trend <0.0001), females (LSM = -6.41, 95% CI: 19.12-6.30, P for trend <0.0001) and current or former smokers (LSM = -21.55, 95% CI: 36.14 to -6.97, P < 0.02). Compared to that of participants using clean fuels for cooking, PEF of participants using solid fuels were decreased by 3.5 l/min per 2 years over a 4-year follow-up. This cohort study highlights the adverse effects of indoor air pollution on lung function in middle aged and older adults in China.

Eosinophilic Airway Inflammation in Patients with Stable Biomass Smoke- versus Tobacco Smoke-Associated Chronic Obstructive Pulmonary Disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is an inflammatory disease with predominant involvement of neutrophils, macrophages and CD8+ lymphocytes. Eosinophilic airway inflammations are reported in stable state and during acute exacerbations of tobacco smoke-associated COPD (TS-COPD). Women exposed to biomass fuel smoke are known to have eosinophils in sputum. However, little is known about the sputum cellular inflammatory profile in biomass fuel smoke-associated COPD (BMS-COPD). We therefore aimed to compare the sputum cellular inflammatory profile in tobacco smoke- and biomass smoke-associated COPD.

METHODS

The study was conducted in a tertiary care hospital in Goa, India. A total of 113 patients with stable COPD reporting to the outpatient pulmonary clinic were recruited. All participants were ≥ 40 years of age. Sputum induction studies were performed by the method of Pizzichini et al. after baseline subject characterization. Significant eosinophilia was defined as induced sputum eosinophils ≥ 3%.

RESULTS

There were 85 TS-COPD and 28 BMS-COPD patients. The mean age [standard deviation (SD)] was 64.7 (7.8) and 63.0 years (8.3), p = 0.32 in TS and BMS-COPD, respectively. Eighteen subjects (21.1%) were female smokers. The smoking pack-year median [interquartile range (IQR)] was 36 (20, 58) and hour-years of biomass smoke exposure mean (SD) was 192.4 (61). The TS-COPD and BMS-COPD cases showed a post-bronchodilator forced expiratory volume in one second (FEV1%) mean (SD) of 57.9 (17.1), and 62.6 (19.4), p= 0.22, respectively. Both groups had similar symptoms and severity of disease. Induced sputum total cell count per gram of sputum × 10⁶ mean (SD) was 3.05 (1.53) for TS-COPD, and 2.55(1.37) for BMS-COPD p=0.12. The neutrophils % mean (SD) was 86.4 (16.5) and 87.9 (10.2), p = 0.64; eosinophils % median (IQR) was 2.5 (1, 10) and 8 (2, 12.8), p = 0.07; lymphocytes % median (IQR) was 0 (0, 0.75) and 0 (0, 1) p = 0.13; macrophages % median (IQR) was 2.5 (0.75, 5.7) and 1 (0, 4.7) p = 0.13; and significant eosinophilia (eosinophils ≥3%) was 42 (49.4%) and 20 (71%), p=0.04, for TS-COPD and BMS-COPD, respectively.

CONCLUSIONS

For similar severity of disease and clinical symptoms, significant eosinophilic inflammation was observed in stable BMS-COPD, while both groups had similar neutrophilic inflammation.

PARTICIPANT CONSENT

Obtained.

ETHICS APPROVAL

The study was approved by the Institutional Ethics Committee of the Goa Medical College, Goa, India.

COMPETING INTERESTS

The authors declare no competing financial interests.

The role of environmental exposure to non-cigarette smoke in lung disease

Chronic exposure to household indoor smoke and outdoor air pollution is a major contributor to global morbidity and mortality. The majority of these deaths occur in low and middle-income countries. Children, women, the elderly and people with underlying chronic conditions are most affected. In addition to reduced lung function, children exposed to biomass smoke have an increased risk of developing lower respiratory tract infections and asthma-related symptoms. In adults, chronic exposure to biomass smoke, ambient air pollution, and opportunistic exposure to fumes and dust are associated with an increased risk of developing chronic bronchitis, chronic obstructive pulmonary disease (COPD), lung cancer and respiratory infections, including tuberculosis. Here, we review the evidence of prevalence of COPD in people exposed to non-cigarette smoke. We highlight mechanisms that are likely involved in biomass-smoke exposure-related COPD and other lung diseases. Finally, we summarize the potential preventive and therapeutic strategies for management of COPD induced by non-cigarette smoke exposure.

In utero and lactational exposure of DEHP increases the susceptibility of prostate carcinogenesis in male offspring through PSCA hypomethylation

As an ubiquitous environmental endocrine disruptor, di(2-ethylhexyl) phthalate (DEHP) has been shown to interfere with the development of reproductive organs and induce pathological changes in prostate. Our previous finding showed that in utero and lactational (IUL) DEHP exposure could disrupt the balance of testosterone and estrogen and increase the susceptibility of prostate carcinogenesis. The purpose of this study is to investigate whether the early-life specific epigenetic modifications could mediate the effect of DEHP exposure on prostate carcinogenesis in rodents, for epigenetic modifications play important roles in regulating prostate carcinogenesis. The pregnant rats were treated with corn oil (negative control) or DEHP at 0.01, 0.1 and 1 mg/kg BW/day from GD7 to PND21. On PND21, the expression and DNA methylation change of six prostate carcinogenesis-related genes (ESR2/GSTP1/NKX3.1/PSCA/PTGS2/Rassf1a) were assessed through SYBR-Green real-time PCR combined with pyrosequencing assay in F1 male offspring. On PND196, the relationship b(STP1, PSCA and PTGS2 in a dose-dependent manner, which were positively correlated with PIN scores, Gleason scores, serum PSA concentrations and negatively correlated with prostate/body weight ratio on PND196. Meanwhile, 1 mg/kg BW/day DEHP markedly reduced DNA methylation level of PSCA in all studied CpG sites. Significant inverse correlations between methylation levels of the promoter CpG site and PSCA mRNA expression were observed. These results indicated that transcriptional changes of GSTP1, PSCA and PTGS2 induced by DEHP exposure might be contribute to the increasing susceptibility of prostate carcinogenesis in late life. Moreover, hypomethylation of PSCA could mediate the effect of DEHP on prostate carcinogenesis in rats.

Evidence of Biomass Smoke Exposure as a Causative Factor for the Development of COPD

Chronic obstructive pulmonary disease (COPD) is a progressive disease of the lungs characterised by chronic inflammation, obstruction of airways, and destruction of the parenchyma (emphysema). These changes gradually impair lung function and prevent normal breathing. In 2002, COPD was the fifth leading cause of death, and is estimated by the World Health Organisation (WHO) to become the third by 2020. Cigarette smokers are thought to be the most at risk of developing COPD. However, recent studies have shown that people with life-long exposure to biomass smoke are also at high risk of developing COPD. Most common in developing countries, biomass fuels such as wood and coal are used for cooking and heating indoors on a daily basis. Women and children have the highest amounts of exposures and are therefore more likely to develop the disease. Despite epidemiological studies providing evidence of the causative relationship between biomass smoke and COPD, there are still limited mechanistic studies on how biomass smoke causes, and contributes to the progression of COPD. This review will focus upon why biomass fuels are used, and their relationship to COPD. It will also suggest methodological approaches to model biomass exposure in vitro and in vivo.

Aging, Health, and Quality of Life for Older People Living With HIV in Sub-Saharan Africa: A Review and Proposed Conceptual Framework

OBJECTIVE

The number of people living with HIV (PLWH) over 50 years old in sub-Saharan Africa is predicted to triple in the coming decades, to 6-10 million. Yet, there is a paucity of data on the determinants of health and quality of life for older PLWH in the region.

METHODS

A review was undertaken to describe the impact of HIV infection on aging for PLWH in sub-Saharan Africa.

RESULTS

We (a) summarize the pathophysiology and epidemiology of aging with HIV in resource-rich settings, and (b) describe how these relationships might differ in sub-Saharan Africa, (c) propose a conceptual framework to describe determinants of quality of life for older PLWH, and (d) suggest priority research areas needed to ensure long-term gains in quality of life for PLWH in the region.

CONCLUSIONS

Differences in traditional, lifestyle, and envirnomental risk factors, as well as unique features of HIV epidemiology and care delivery appear to substantially alter the contribution of HIV to aging in sub-Saharan Africa. Meanwhile, unique preferences and conceptualizations of quality of life will require novel measurement and intervention tools. An expanded research and public health infrastructure is needed to ensure that gains made in HIV prevention and treamtent are translated into long-term benefits in this region.

Exposure to Ambient Particulate Matter Induced COPD in a Rat Model and a Description of the Underlying Mechanism

While the health effects of air pollution have been an international public health concern since at least the 1950s, recent research has focused on two broad sources of air pollution, namely, biomass fuel (BMF) and motor vehicle exhaust (MVE). Many studies have shown associations between air pollution PM and exacerbations of pre-existing COPD, but the role of air pollution PM in the development and progression of COPD is still uncertain. The current study indicates that rats can develop pronounced COPD following chronic exposure to air pollution PM (BMF and MVE), as characterized by lung function reduction, mucus metaplasia, lung and systemic inflammation, emphysema, and small airway remodeling. Comparative analyses demonstrate that both BMF and MVE activate similar pathogenesis that are linked to the development of COPD. These findings also show that some differences are found in the lungs of rats exposed to BMF or MVE, which might result in different phenotypes of COPD.

Immune-mediated inflammation in the pathogenesis of emphysema: insights from mouse models

The cellular mechanisms that result in the initiation and progression of emphysema are clearly complex. A growing body of human data combined with discoveries from mouse models utilizing cigarette smoke exposure or protease administration have improved our understanding of emphysema development by implicating specific cell types that may be important for the pathophysiology of chronic obstructive pulmonary disease. The most important aspects of emphysematous damage appear to be oxidative or protease stress and sustained macrophage activation and infiltration of other immune cells leading to epithelial damage and cell death. Despite the identification of these associated processes and cell types in many experimental studies, the reasons why cigarette smoke and other pollutants result in unremitting damage instead of injury resolution are still uncertain. We propose an important role for macrophages in the sequence of events that lead and maintain this chronic tissue pathologic process in emphysema. This model involves chronic activation of macrophage subtypes that precludes proper healing of the lung. Further elucidation of the cross-talk between epithelial cells that release damage-associated signals and the cellular immune effectors that respond to these cues is a critical step in the development of novel therapeutics that can restore proper lung structure and function to those afflicted with emphysema.

A Systematic Review of Innate Immunomodulatory Effects of Household Air Pollution Secondary to the Burning of Biomass Fuels

BACKGROUND

Household air pollution (HAP)-associated acute lower respiratory infections cause 455,000 deaths and a loss of 39.1 million disability-adjusted life years annually. The immunomodulatory mechanisms of HAP are poorly understood.

OBJECTIVES

The aim of this study was to conduct a systematic review of all studies examining the mechanisms underlying the relationship between HAP secondary to solid fuel exposure and acute lower respiratory tract infection to evaluate current available evidence, identify gaps in knowledge, and propose future research priorities.

METHODS

We conducted and report on studies in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. In all, 133 articles were fully reviewed and main characteristics were detailed, namely study design and outcome, including in vivo versus in vitro and pollutants analyzed. Thirty-six studies were included in a nonexhaustive review of the innate immune system effects of ambient air pollution, traffic-related air pollution, or wood smoke exposure of developed country origin. Seventeen studies investigated the effects of HAP-associated solid fuel (biomass or coal smoke) exposure on airway inflammation and innate immune system function.

RESULTS

Particulate matter may modulate the innate immune system and increase susceptibility to infection through a) alveolar macrophage-driven inflammation, recruitment of neutrophils, and disruption of barrier defenses; b) alterations in alveolar macrophage phagocytosis and intracellular killing; and c) increased susceptibility to infection via upregulation of receptors involved in pathogen invasion.

CONCLUSIONS

HAP secondary to the burning of biomass fuels alters innate immunity, predisposing children to acute lower respiratory tract infections. Data from biomass exposure in developing countries are scarce. Further study is needed to define the inflammatory response, alterations in phagocytic function, and upregulation of receptors important in bacterial and viral binding. These studies have important public health implications and may lead to the design of interventions to improve the health of billions of people daily.

Biomass smoke as a risk factor for chronic obstructive pulmonary disease: effects on innate immunity

Chronic obstructive pulmonary disease (COPD), a major cause of mortality and morbidity worldwide, is considered an archetypical disease of innate immunity, where inhaled particles and gases trigger an inflammatory response, favoring tissue proliferation in small airways and tissue destruction in lung parenchyma, in addition to the recruitment of immune cells to these compartments. Although cigarette smoking is still considered the main risk factor for developing COPD, the trend of proposing biomass smoke (BS) exposure as a principal risk factor is gaining importance, as around 3 billion people worldwide are exposed to this pollutant daily. A considerable amount of evidence has shown the potential of BS as an enhancer of lung inflammation. However, an impairment of some innate immune responses after BS exposure has also been described. Regarding the mechanisms by which biomass smoke alters the innate immune responses, three main classes of cell surface receptors-the TLRs, the scavenger receptors and the transient receptor potential channels-have shown the ability to transduce signals initiated after BS exposure. This article is an updated and comprehensive review of the immunomodulatory effects described after the interaction of BS components with these receptors.

Clinically relevant subgroups in COPD and asthma

As knowledge of airways disease has grown, it has become apparent that neither chronic obstructive pulmonary disease (COPD) nor asthma is a simple, easily defined disease. In the past, treatment options for both diseases were limited; thus, there was less need to define subgroups. As treatment options have grown, so has our need to predict who will respond to new drugs. To date, identifying subgroups has been largely reported by detailed clinical characterisation or differences in pathobiology. These subgroups are commonly called "phenotypes"; however, the problem of defining what constitutes a phenotype, whether this should include comorbid diseases and how to handle changes over time has led to the term being used loosely. In this review, we describe subgroups of COPD and asthma patients whose clinical characteristics we believe have therapeutic or major prognostic implications specific to the lung, and whether these subgroups are constant over time. Finally, we will discuss whether the subgroups we describe are common to both asthma and COPD, and give some examples of how treatment might be tailored in patients where the subgroup is clear, but the label of asthma or COPD is not.

Exposure to household air pollution from wood combustion and association with respiratory symptoms and lung function in nonsmoking women: results from the RESPIRE trial, Guatemala

BACKGROUND

With 40% of the world's population relying on solid fuel, household air pollution (HAP) represents a major preventable risk factor for COPD (chronic obstructive pulmonary disease). Meta-analyses have confirmed this relationship; however, constituent studies are observational, with virtually none measuring exposure directly.

OBJECTIVES

We estimated associations between HAP exposure and respiratory symptoms and lung function in young, nonsmoking women in rural Guatemala, using measured carbon monoxide (CO) concentrations in exhaled breath and personal air to assess exposure.

METHODS

The Randomized Exposure Study of Pollution Indoors and Respiratory Effects (RESPIRE) Guatemala study was a trial comparing respiratory outcomes among 504 women using improved chimney stoves versus traditional cookstoves. The present analysis included 456 women with data from postintervention surveys including interviews at 6, 12, and 18 months (respiratory symptoms) and spirometry and CO (ppm) in exhaled breath measurements. Personal CO was measured using passive diffusion tubes at variable times during the study. Associations between CO concentrations and respiratory health were estimated using random intercept regression models.

RESULTS

Respiratory symptoms (cough, phlegm, wheeze, or chest tightness) during the previous 6 months were positively associated with breath CO measured at the same time of symptom reporting and with average personal CO concentrations during the follow-up period. CO in exhaled breath at the same time as spirometry was associated with lower lung function [average reduction in FEV1 (forced expiratory volume in 1 sec) for a 10% increase in CO was 3.33 mL (95% CI: -0.86, -5.81)]. Lung function measures were not significantly associated with average postintervention personal CO concentrations.

CONCLUSIONS

Our results provide further support for the effects of HAP exposures on airway inflammation. Further longitudinal research modeling continuous exposure to particulate matter against lung function will help us understand more fully the impact of HAP on COPD.

Pathogenic mechanisms in chronic obstructive pulmonary disease due to biomass smoke exposure

Chronic obstructive pulmonary disease (COPD) mortality and morbidity have increased significantly worldwide in recent decades. Although cigarette smoke is still considered the main risk factor for the development of the disease, estimates suggest that between 25% and 33% of COPD patients are non-smokers. Among the factors that may increase the risk of developing COPD, biomass smoke has been proposed as one of the most important, affecting especially women and children in developing countries. Despite the epidemiological evidence linking exposure to biomass smoke with adverse health effects, the specific cellular and molecular mechanisms by which this pollutant can be harmful for the respiratory and cardiovascular systems remain unclear. In this article we review the main pathogenic mechanisms proposed to date that make biomass smoke one of the major risk factors for COPD.

Expression microarray as a tool to identify differentially expressed genes in horses suffering from inflammatory airway disease

BACKGROUND

Inflammatory airway disease (IAD) affects performance and well-being of horses. Diagnosis is primarily reached by bronchoalveolar lavage (BAL) cytology which is invasive and requires sedation.

OBJECTIVES

The purpose of this study was to identify differential gene expression in peripheral blood of horses with IAD using species-specific expression microarrays.

METHODS

Equine gene expression microarrays were used to investigate global mRNA expression in circulating leukocytes from healthy, IAD-affected, and low-performing Standardbred and endurance horses.

RESULTS

Nine genes in Standardbred and 61 genes in endurance horses were significantly differentially regulated (P < .001). These genes were related to inflammation (eg, ALOX15B, PLA2G12B, and PENK), oxidant/antioxidant balance (eg, DUOXA2 and GSTO1-1), and stress (eg, V1aR, GRLF1, Homer-2, and MAOB). All these genes were up-regulated, except down-regulated Homer-2 and MAOB. DUOXA2, ALOX15B, PLA2G12B, MAOB, and GRLF1 expression was further validated by RT-qPCR. An increase in glutathione peroxidase (GPx) activity in heparinized whole blood of IAD-affected Standardbred (P = .0025) and endurance horses (P = .0028) also suggests a deregulation of the oxidant/antioxidant balance. There was good correlation (r = .7354) between BAL neutrophil percentage and whole blood GPx activity in all horses.

CONCLUSIONS

This study showed that circulating blood cell gene expression reflects inflammatory responses in tissues. Whether any of the genes have potential for diagnostic applications in the future remains to be investigated. Although not specific for IAD, whole blood GPx activity appears to be correlated with BAL neutrophil percentage. This finding should be further assessed by testing a larger number of horses.