Acute effects of environmental tobacco smoke and dried dung smoke on lung histopathology in rabbits

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.

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.

Effects of emissions from sugar cane burning on the trachea and lungs of Wistar rats

Objective:

To evaluate the effects of exposure to emissions from sugar cane burning on inflammatory mechanisms in tissues of the trachea and lung parenchyma in Wistar rats after different periods of exposure.

Methods:

This was an experimental open randomized study. The animals were divided into four groups: a control group (CG) underwent standard laboratory conditions, and three experimental groups were exposed to emissions from sugar cane burning over different periods of time, in days-1 (EG1), 7 (EG7), and 21 (EG21). After euthanasia with 200 mg/kg of ketamine/xylazine, fragments of trachea and lung were collected and fixed in 10% formalin. Histological analyses were performed with H&E and picrosirius red staining.

Results:

No inflammatory infiltrates were found in the tissues of CG rats. The histological examination of tissues of the trachea and lung parenchyma revealed that the inflammatory process was significantly more intense in EG7 than in the CG (p < 0.05 and p < 0.01, respectively). In comparison with the CG and EG1, angiogenesis in the lung parenchyma and collagen deposition in tracheal tissues were significantly greater only in EG21 (p < 0.001 and p < 0.01, respectively).

Conclusions:

In this sample, emissions from sugar cane burning induced acute focal and diffuse inflammation in the lamina propria of tracheal tissues, with no loss of ciliated epithelial tissue. In the lung parenchyma of the animals in the experimental groups, there was interstitial and alveolar edema, together with polymorphonuclear cell infiltrates.

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.

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.

Indoor fuel exposure and the lung in both developing and developed countries: an update

Almost 3 billion people worldwide burn solid fuels indoors. Despite the large population at risk worldwide, the effect of exposure to indoor solid fuel smoke has not been adequately studied. Indoor air pollution from solid fuel use is strongly associated with chronic obstructive pulmonary disease, acute respiratory tract infections, and lung cancer, and weakly associated with asthma, tuberculosis, and interstitial lung disease. Tobacco use further potentiates the development of respiratory disease among subjects exposed to solid fuel smoke. There is a need to perform additional interventional studies in this field.

Exposure to biomass smoke as a cause for airway disease in women and children

PURPOSE OF REVIEW

An estimated 3 billion people (about half the world's population) burn biomass fuel (wood, crop residues, animal dung and coal) for cooking and heating purposes exposing a large population, especially women and children, to high levels of indoor air pollution. Biomass smoke comprises gaseous air pollutants as well as particulate matter air pollutants, which have significant harmful effects.

RECENT FINDINGS

Exposure to biomass smoke is a major contributor to morbidity and mortality. Children, women and the elderly are most affected. Apart from poor lung growth seen in growing children, the risk of developing respiratory tract infections (both upper as well as lower) is greatly increased in children living in homes using biomass. Women who spend many hours cooking food in poorly ventilated homes develop chronic obstructive lung disease (COPD), asthma, respiratory tract infections, including tuberculosis and lung cancer. It has been argued that exposure to biomass fuel smoke is a bigger risk factor for COPD than tobacco smoking.

SUMMARY

Physicians need to be aware about the harmful effects of biomass smoke exposure and ensure early diagnosis and appropriate management to reduce the disease burden. More research needs to be done to study health effects due to biomass smoke exposure better. Reducing the exposure to biomass smoke through proper home ventilation, home design and, if possible, change of biomass to cleaner fuels is strongly recommended in order to reduce biomass smoke-induced mortality and morbidity.

Lung tissue apoptosis in abdominal hypertension : Apoptosis and necrosis of lung tissue in abdominal hypertension

OBJECTIVES

The aim of this study was to evaluate lung tissue histopathologic changes and the number of apoptosis with the increase of abdominal pressure.

METHODS

The study rats were randomly assigned into the following five groups: a sham operated group and groups 1, 2, 3 and 4, in which the intra-abdominal pressure was increased to 11, 15, 18 and 22 mmHg for 60 min, respectively. Lungs were harvested for histopathologic changes and the tissue apoptotic analysis were carried out in a blinded manner.

RESULTS

All of the data showed that the number of apoptotic cells and necrosis were increased in accordance with the pressure level. However, this increase was statistically significant, especially in groups 3 and 4 (18 and 22 mmHg, respectively; p < 0.05) when compared to the sham operated rats. There were no differences observed between groups 1 and 2 (11 and 15 mmHg, respectively) and the sham operated rats. There was also no difference between groups 1 and 2. There were findings of coagulation necrosis and the number of apoptotic cells linearly increased when the abdominal pressure was increased. The cut-off value was 15 mmHg.

CONCLUSION

The available findings suggest that intra-abdominal pressure greater than 15 mmHg could irreversibly damage pulmonary cells and both coagulation necrosis parameters and the number of apoptosis increase in accordance with the pressure level.

Effect of secondhand smoke on occupancy of nicotinic acetylcholine receptors in brain

CONTEXT

Despite progress in tobacco control, secondhand smoke (SHS) exposure remains prevalent worldwide and is implicated in the initiation and maintenance of cigarette smoking.

OBJECTIVE

To determine whether moderate SHS exposure results in brain α(4)β(2)* nicotinic acetylcholine receptor (nAChR) occupancy.

DESIGN, SETTING, AND PARTICIPANTS

Positron emission tomography scanning and the radiotracer 2-[18F]fluoro-3-(2(S)azetidinylmethoxy) pyridine (also known as 2-[(18)F]fluoro-A-85380, or 2-FA) were used to determine α(4)β(2)* nAChR occupancy from SHS exposure in 24 young adult participants (11 moderately dependent cigarette smokers and 13 nonsmokers). Participants underwent two bolus-plus-continuous-infusion 2-FA positron emission tomography scanning sessions during which they sat in the passenger's seat of a car for 1 hour and either were exposed to moderate SHS or had no SHS exposure. The study took place at an academic positron emission tomography center. Main Outcome Measure  Changes induced by SHS in 2-FA specific binding volume of distribution as a measure of α(4)β(2)* nAChR occupancy.

RESULTS

An overall multivariate analysis of variance using specific binding volume of distribution values revealed a significant main effect of condition (SHS vs control) (F(1,22) = 42.5, P < .001) but no between-group (smoker vs nonsmoker) effect. Exposure to SHS led to a mean 19% occupancy of brain α(4)β(2)* nAChRs (1-sample t test, 2-tailed, P < .001). Smokers had both a mean 23% increase in craving with SHS exposure and a correlation between thalamic α(4)β(2)* nAChR occupancy and craving alleviation with subsequent cigarette smoking (Spearman ρ = -0.74, P = .01).

CONCLUSIONS

Nicotine from SHS exposure results in substantial brain α(4)β(2)* nAChR occupancy in smokers and nonsmokers. Study findings suggest that such exposure delivers a priming dose of nicotine to the brain that contributes to continued cigarette use in smokers. This study has implications for both biological research into the link between SHS exposure and cigarette use and public policy regarding the need to limit SHS exposure in cars and other enclosed spaces.

Pulmonary toxicity of chronic exposure to tobacco and biomass smoke in rats

OBJECTIVE

The objective of this study was to examine the separate and combined effects of tobacco and biomass smoke exposure on pulmonary histopathology in rats.

INTRODUCTION

In addition to smoking, indoor pollution in developing countries contributes to the development of respiratory diseases.

METHODS

Twenty-eight adult rats were divided into four groups as follows: control group (Group I, no exposure to tobacco or biomass smoke), exposed to tobacco smoke (Group II), exposed to biomass smoke (Group III), and combined exposure to tobacco and biomass smoke (Group IV). After six months the rats in all four groups were sacrificed. Lung tissue samples were examined under light microscopy. The severity of pathological changes was scored.

RESULTS

Group II differed from Group I in all histopathological alterations except intraparenchymal vascular thrombosis. There was no statistically significant difference in histopathological changes between the subjects exposed exclusively to tobacco smoke (Group II) and those with combined exposure to tobacco and biomass smoke (Group IV). The histopathological changes observed in Group IV were found to be more severe than those in subjects exposed exclusively to biomass smoke (Group III).

DISCUSSION

Chronic exposure to tobacco and biomass smoke caused an increase in severity and types of lung injury.

CONCLUSION

Exposure to cigarette smoke caused serious damage to the respiratory system, particularly with concomitant exposure to biomass smoke.

Indoor air pollution from biomass burning activates Akt in airway cells and peripheral blood lymphocytes: a study among premenopausal women in rural India

Biomass burning is a major source of indoor air pollution in rural India. The authors investigated in this study whether cumulative exposures to biomass smoke cause activation of the serine/threonine kinase Akt in airway cells and peripheral blood lymphocytes (PBL). For this, the authors enrolled 87 premenopausal (median age 34 years), nonsmoking women who used to cook with biomass (wood, dung, crop wastes) and 85 age-matched control women who cooked with cleaner fuel liquefied petroleum gas. Immunocytochemical and immunoblotting assays revealed significantly higher levels of phosphorylated forms of Akt protein (p-Akt(ser473) and p-Akt(thr308)) in PBL, airway epithelial cells, alveolar macrophages, and neutrophils in sputum of biomass-using women than control. Akt activation in biomass users was associated with marked rise in generation of reactive oxygen species and concomitant depletion of superoxide dismutase. Measurement of particulate matter having a diameter of less than 10 and 2.5 µm in indoor air by real-time aerosol monitor showed 2 to 4 times more particulate pollution in biomass-using households, and Akt activation was positively associated with particulate pollution after controlling potential confounders. The findings suggest that chronic exposure to biomass smoke activates Akt, possibly via generation of oxidative stress.

Effect of diphenhydramine on myocardial injury caused by organophosphate poisoning

BACKGROUND

The aim of this experimental study was to investigate whether diphenhydramine could prevent or diminish myocardial injury caused by organophosphate poisoning as defined by histologic findings and cardiac troponin I (cTnI) levels.

METHODS

Twenty-four Sprague-Dawley rats were divided into equal three groups. Group 1 did not receive any agent during the experiment. Group 2 received 0.8 g/kg fenthion subcutaneously followed by normal saline (3 ml/kg) intramuscularly 30 minutes later. Group 3 received 0.8 g/kg fenthion subcutaneously, followed by diphenhydramine 30 mg/kg (in 3 ml/kg) intramuscularly 30 minutes later. All rats underwent laparotomy and thoracotomy while under anesthesia at 24 hours.

RESULTS

Treatment with diphenhydramine significantly decreased the blood cTnI levels. Additionally, diphenhydramine significantly reduced myocardial injury, including edema, inflammation, vacuolization and necrosis, as determined by pathologic scoring.

CONCLUSION

Organophosphate poisoning can cause myocardial injury as determined by measurement of I cTnI levels. Our study demonstrates that this injury can be attenutated by the administration of diphenydramine.

Effects of caffeic acid phenethyl ester on the histopathological changes in the lungs of cigarette smoke-exposed rabbits

We aimed at evaluating the effects of caffeic acid phenethyl ester (CAPE) on the histopathological changes in the lungs of rabbits exposed to cigarette smoke exposure. Four groups with six rabbits each were as follows: cigarette smoke group, CAPE group, cigarette smoke + CAPE group and control group. The cigarette smoke group was exposed to cigarette smoke 1 hr daily for 1 month. The CAPE group was administered intraperitoneal CAPE. The CAPE + cigarette smoke group was both exposed to cigarette smoke and was administered intraperitoneal CAPE. The control group was exposed to clean air. After 1 month, the rabbits were killed and the lung tissues were examined histopathologically. Peribronchial and intraparenchymal inflammation, intraparenchymal vascular congestion and thrombosis, intraparenchymal haemorrhage, respiratory epithelial proliferation, number of macrophages in the bronchiolar and alveolar lumen, alveolar destruction, emphysematous changes and bronchoalveolar haemorrhage scores were significantly higher in the cigarette smoke group than in the control group. Administration of CAPE to cigarette smoke-exposed rabbits significantly prevented all these changes. CAPE seems to have significant preventive effects on the severe histopathological changes in the lungs associated with cigarette smoke exposure. However, in some instances, it may not alter the progression to fibrosis.

The neuroprotective effects of caffeic acid phenethyl ester (CAPE) in the hippocampal formation of cigarette smoke exposed rabbits

BACKGROUND

In this study, the neuroprotective effects of caffeic acid phenethyl ester (CAPE) in the hippocampus of cigarette smoke exposed rabbits were investigated.

MATERIALS AND METHODS

Eighteen rabbits were used as experimental subjects and divided into three equal groups. The control group (Group A) was exposed to clean air. Rabbits in the cigarette smoke (CS) group (Group B) were exposed to cigarette smoke 1 hour daily in a room within a glass chamber for 4 weeks. Animals in the CS+CAPE group (Group C) were exposed to cigarette smoke as in Group B and administered CAPE (10 micromol/kg/day) intraperitoneally for 4 weeks just before the exposure to cigarette smoke. Rabbits in all three groups were sacrificed with intraperitoneal administration of 100 mg/kg sodium pentothal and their brains were removed immediately. In the hippocampal formation samples of left hemispheres, the levels of malondialdehyde (MDA) and superoxide dismutase (SOD) were measured and the number of apoptotic neurons was counted by 'terminal transferase dUTP nick end labelling' (TUNEL) assay in the right hippocampal formation.

RESULTS

We found that MDA levels increased significantly in the Group B rabbits compared with the control group (Group A; p = 0.001). In contrast, SOD activities decreased significantly in Group B rabbits compared with the control group (p = 0.001). In the CAPE treated rabbits (Group C), MDA levels decreased and SOD activities increased significantly as compared with Group B rabbits (p = 0.002, p = 0.002, respectively). The number of apoptotic neurons (TUNEL+) in the CA1, CA2, CA3 and dentate gyrus areas of rabbits' hippocampal formation were significantly increased in Group B rabbits compared with the control group. On the other hand, the number of apoptotic neurons in the hippocampus areas was decreased significantly in Group C rabbits compared with Group B rabbits.

CONCLUSION

These findings suggest that cigarette smoking induces apoptosis in the hippocampal formation of rabbits and CAPE has a protective role against this induction.

Lithium-induced lung toxicity in rats: the effect of caffeic acid phenethyl ester (CAPE)

AIMS

We aimed to evaluate the effects of caffeic acid phenethyl ester (CAPE) on lithium (Li)-induced lung toxicity.

METHODS

Twenty-two adult male Wistar albino rats weighing between 280 and 300 g were used. The rats were randomly divided into three groups: control, Li and Li+CAPE groups. Li and CAPE were co-administered intraperitoneally twice daily for 4 weeks. Control rats were given 0.9% NaCl during the same period. All the rats were allowed to feed ad libitum until midnight after they had received the proposed treatment.

RESULTS

In the Li group, peribronchial and intraparenchymal lymphocyte and macrophage infiltration were observed. Atypical type II pneumocytes, alveolar destruction and emphysematous changes were also detected. Lymphocyte and macrophage infiltration was significantly decreased in the Li+CAPE group compared with the Li group. Alveolar destruction, emphysematous changes and intraparenchymal mononuclear cell infiltration were also recovered to a level close to the control group. Malondialdehyde (MDA) levels were increased in the Li group compared with the control group. CAPE administration decreased the MDA levels in the Li+CAPE group.

CONCLUSIONS

CAPE was found to associate with histopathological changes recovery in the lungs and oxidative stress due to Li treatment.