Scanning electron microscopic evaluation of the alterations induced by polluted air in the rabbit bronchial epithelium

Exposure to Environmental Toxins: Potential Implications for Stroke Risk via the Gut- and Lung-Brain Axis

Recent evidence indicates that exposure to environmental toxins, both short-term and long-term, can increase the risk of developing neurological disorders, including neurodegenerative diseases (i.e., Alzheimer's disease and other dementias) and acute brain injury (i.e., stroke). For stroke, the latest systematic analysis revealed that exposure to ambient particulate matter is the second most frequent stroke risk after high blood pressure. However, preclinical and clinical stroke investigations on the deleterious consequences of environmental pollutants are scarce. This review examines recent evidence of how environmental toxins, absorbed along the digestive tract or inhaled through the lungs, affect the host cellular response. We particularly address the consequences of environmental toxins on the immune response and the microbiome at the gut and lung barrier sites. Additionally, this review highlights findings showing the potential contribution of environmental toxins to an increased risk of stroke. A better understanding of the biological mechanisms underlying exposure to environmental toxins has the potential to mitigate stroke risk and other neurological disorders.

Effect of particles of ashes produced from sugarcane burning on the respiratory system of rats

The practice of burning sugarcane obtained by non-mechanized harvesting exposes workers and the people of neighboring towns to high concentrations of particulate matter (PM) that is harmful to health, and may trigger a series of cardiorespiratory diseases. The aim of this study was to analyze the chemical composition of the micro-particles coming from sugarcane burning residues and to verify the effects of this micro-particulate matter on lung and tracheal tissues. Micro-particulate matter (PM10) was obtained by dissolving filter paper containing burnt residues in NaCl solution. This material was instilled into the Wistar rats' nostrils. Histological analyses (hematoxylin and eosin - HE) of cardiac, lung and tracheal tissues were performed. Inflammatory mediators were measured in lung tissues by using ELISA. The chemical composition of the particulate material revealed a large quantity of the phthalic acid ester, high concentrations of phenolic compounds, anthracene and polycyclic aromatic hydrocarbons (PAH). Histological analysis showed a reduction in subjacent conjunctive tissue in the trachea, lung inflammation with inflammatory infiltrate formation and reduction of alveolar spaces and a significant increase (p<0.05) in the release of IL-1α, IL-1β, IL-6, and INF-γ in the group treated with PM10 when compared to the control group. We concluded that the burning sugarcane residues release many particles, which have toxic chemical compounds. The micro-particulate matter can induce alterations in the respiratory system.

Is the trachea a marker of the type of environmental pollution?

OBJECTIVES/HYPOTHESIS

The differentiated character of changes in the mucous relief of the trachea as induced by air containing pollutants from the wastes of nickel-, mercury-, and cement-producing plants and by Candida albicans occurring in the waste disposal site of a large town are identified. The trachea was chosen because it is the entrance gate for the penetration of polluted air into the lungs. Changes on the trachea influence the character and extent of changes in lungs.

STUDY DESIGN

Histological study with Viennese grey strain laboratory rabbits and rats caught directly on an investigated site.

METHODS

We present new results of the functional morphology of the respiratory system as the results of scanning and transmission electron microscopy studies that can reveal character and range of damage of mucosal relief of trachea relevant to the functional dynamics of mucociliary clearance. Under physiological conditions this mechanism allows that only respirable dust particles enter the deep respiratory tract.

RESULTS

In case of a damaged tracheal relief because of exposure to various aerosols, the functional morphology is changed, which aids in understanding the mechanisms damaging to mucociliary clearance induced by living in heavily polluted areas.

CONCLUSION

Understanding of these morphological changes on base of detailed electron microscopic findings sheds new light on elaborating novel diagnostic methods for clinical practice.

Respiratory changes due to long-term exposure to urban levels of air pollution: a histopathologic study in humans

STUDY OBJECTIVES

To evaluate the potential associations between long-term exposure to air pollution and histopathologic evidence of damage to the lungs in humans.

DESIGN

Lung tissue samples were collected during necropsies of individuals who died due to violent causes, selected on the basis of their exposure background.

PATIENTS

The exposed group was composed of individuals who lived in Guarulhos, an area with high mean levels of inhalable particles. The control group was composed of individuals who lived in two cities with economies based on agricultural activities: Ribeirão Preto and Ourinhos.

INTERVENTIONS

Information about cigarette smoking and occupational exposure was obtained from family members.

MEASUREMENTS AND RESULTS

Morphometric evaluation of the main bronchus was conducted to determine the volume ratio of submucosal glands. Histopathologic alterations of the bronchioli were evaluated by scoring the presence of inflammatory reaction, wall thickening, and secretory hyperplasia. The number of spots of carbon deposition was counted along the regions of lymphatic drainage (visceral pleura and axial connective tissue around bronchi and blood vessels). Statistical analysis was done by means of regression models controlled for age, smoking, and occupational exposure. Lungs collected from the high pollution area presented evidence of more histopathologic damage in comparison to those from the clean environments. These effects were observed even after controlling for individual differences in age, sex, and cigarette smoking levels.

CONCLUSIONS

These results suggest that long-term exposure to air pollution may contribute to the pathogenesis of airway disease, and that urban levels of air pollution have adverse effects on the respiratory tract.

Pulmonary endocrine cell hyperplasia and papilloma in rats induced by intratracheal injections of extract from particulate air pollutants

We investigated the effect of intratracheal injections of an extract of suspended particulate matter (SPM) obtained from the urban ambient air of Tokyo, upon the development of proliferative lesions of pulmonary endocrine cells (PECs) in the rat. We also examined the modification effects of nitrogen dioxide, sulfur dioxide, or both of them on the PEC lesions. Male F344 rats were divided into six experimental groups of 5 animals each. Twenty animals were treated with intratracheal instillations of SPM admixed with carbon once a week for 4 weeks with or without additional gaseous exposure (6 ppm nitrogen dioxide or 4 ppm sulfur dioxide) 16 hrs a day for 11 months. Five animals were given intratracheal injections of carbon suspended in saline and the other five were untreated. The subcardiac lobes of the right lung were fixed with 4% paraformaldehyde, and embedded in paraffin. PEC hyperplasias and papillomas were counted in 200 serial sections, 4 microns thick. The average incidences of PEC hyperplasia in the untreated animals and in those treated with carbon were 194 and 200/cm3, respectively. The average incidences of PEC hyperplasia in the animals exposed to SPM tar only, SPM tar plus nitrogen dioxide and sulfur dioxide, SPM tar with nitrogen dioxide and SPM tar with sulfur dioxide were 376, 378, 372 and 349/cm3, respectively. These were significantly higher than the levels of the control animals, and additional gaseous stimuli had no effect on the incidence of PEC hyperplasia. Besides PEC hyperplasia, a few PEC papillomas were found in the animals treated with SPM tar, regardless of gaseous exposure, but in the control animals no papilloma was evident. Thus, compounds in airborne particulates are considered to be responsible for the development of PEC hyperplasias and papillomas.