Effect of Lung Fibrosis on Glycogen Content in Different Extrapulmonary Tissues

Quercetin ameliorates acute lung injury in a rat model of hepatopulmonary syndrome

BACKGROUND

Common bile duct ligation (BDL) is a rat experimental model to induce biliary cirrhosis. Lung fibrosis and pulmonary vascular angiogenesis and congestion are the most common complications of biliary cirrhosis that is known as hepatopulmonary syndrome. The aim of the present work is to investigate the acute lung injury in a BDL model and to investigate the possible protective effect of quercetin on this injury.

METHODS

Twenty-four adult male albino rats of the Wister strain (weighing 150-250 g). Animals were divided into 3 groups, with 8 rats each: Group I: Sham-operated group (control). Group II: Bile duct ligation group (BDL) sacrificed after 28 days from the surgery. Group III: Quercetin-treated bile duct ligation group (Q-BDL) was given orally by gastric gavage in a dose of 50 mg/kg/day, starting from the 4th day of the operation until the 28th day. At the end of the experiment, at day 28, all rats were sacrificed. Lung specimens were processed to measure Endothelin B receptor gene expression by PCR, lung surfactant by ELISA, "eNO" s by immunohistochemistry. Histological assessment was done using; H&E, Masson's trichrome, PAS, toluidine blue-stained semi-thin sections, transmission electron microscope. Histomorphometric and statistical studies were done.

RESULTS

BDL group showed significant increase in lung index together with mononuclear cellular infiltration denoting lung inflammatory state. Also, the significant increase in pulmonary endothelial nitric oxide synthase ("eNO" s) area percent and endothelin B receptor (ET_B) gene expression indicates enhanced angiogenesis. Pulmonary surfactant concentration was significantly decreased together with thickening of interalveolar septa denoting lung injury and fibrosis. Quercetin led to significant decrease in lung index, pulmonary "eNO" s area percent, ET_B gene expression and significant increase in pulmonary surfactant concentration. Quercetin treatment improved histological changes and morphometric measurements, limited mononuclear cellular infiltration and decreased perivascular and perialveolar collagen deposition.

CONCLUSION

Quercetin ameliorates the hepatopulmonary syndrome-induced lung injury through its anti-inflammatory, antioxidative and antifibrotic effects.

Pectin/chitosan/tripolyphosphate encapsulation protects the rat lung from fibrosis and apoptosis induced by paraquat inhalation

BACKGROUND

Paraquat poisoning leads to lung injury and pulmonary fibrosis. The effect of paraquat encapsulation by previously described Pectin/Chitosan/Tripolyphosphate nanoparticles on its pulmonary toxicity was investigated in present study in a rat model of poison inhalation.

MATERIAL AND METHOD

The rats inhaled nebulized different formulation of paraquat (n = 5) for 30 min in various experimental groups. Lung injury and fibrosis scores, Lung tissue enzymatic activities, apoptosis markers were determined compared among groups.

RESULTS

Encapsulation of paraquat significantly rescued both lung injury and fibrosis scores. Lung MDA level was reduced by encapsulation. Paraquat poisoning led to lung tissue apoptosis as was evidenced by higher Caspase-3 and Bax/Bcl2 expressions in rats subjected to paraquat inhalation instead of normal saline or free nanoparticles. Again, nanoencapsulation reduced these apoptosis markers significantly. Alpha-SMA expression was also reduced by encapsulation. Nanoparticles per se have no or little toxicity as was evidenced by inflammatory and apoptotic markers and histological scores.

CONCLUSION

In a rat model of inhalation toxicity of paraquat, loading of this herbicide on PEC/CS/TPP nanoparticles reduced acute lung injury and fibrosis. The encapsulation also led to lower apoptosis, oxidative stress and alpha-SMA expression in the lung tissue.

Paraquat Inhalation, a Translationally Relevant Route of Exposure: Disposition to the Brain and Male-Specific Olfactory Impairment in Mice

Epidemiological and experimental studies have associated oral and systemic exposures to the herbicide paraquat (PQ) with Parkinson's disease. Despite recognition that airborne particles and solutes can be directly translocated to the brain via olfactory neurons, the potential for inhaled PQ to cause olfactory impairment has not been investigated. This study sought to determine if prolonged low-dose inhalation exposure to PQ would lead to disposition to the brain and olfactory impairment, a prodromal feature of Parkinson's disease. Adult male and female C57BL/6J mice were exposed to PQ aerosols in a whole-body inhalation chamber for 4 h/day, 5 days/week for 4 weeks. Subsets of mice were sacrificed during and after exposure and PQ concentrations in various brain regions (olfactory bulb, striatum, midbrain, and cerebellum) lung, and kidney were quantified via mass spectrometry. Alterations in olfaction were examined using an olfactory discrimination paradigm. PQ inhalation resulted in an appreciable burden in all examined brain regions, with the highest burden observed in the olfactory bulb, consistent with nasal olfactory uptake. PQ was also detected in the lung and kidney, yet PQ levels in all tissues returned to control values within 4 weeks post exposure. PQ inhalation caused persistent male-specific deficits in olfactory discrimination. No effects were observed in females. These data support the importance of route of exposure in determination of safety estimates for neurotoxic pesticides, such as PQ. Accurate estimation of the relationship between exposure and internal dose is critical for risk assessment and public health protection.

Low-dose administration of bleomycin leads to early alterations in lung mechanics

NEW FINDINGS

What is the central question of this study? When do alterations in pulmonary mechanics occur following chronic low-dose administration of bleomycin? What is the main finding and its importance? Remarkably, we report changes in lung mechanics as early as day 7 that corresponded to parameters determined from single-frequency forced oscillation manoeuvres and pressure-volume loops. These changes preceded substantial histological changes or changes in gene expression levels. These findings are significant to refine drug discovery in idiopathic pulmonary fibrosis, where preclinical studies using lung function parameters would enhance the translational potential of drug candidates where lung function readouts are routinely performed in the clinic.

ABSTRACT

Idiopathic pulmonary fibrosis (IPF) is the most widespread form of interstitial lung disease and, currently, there are only limited treatment options available. In preclinical animal models of lung fibrosis, the effectiveness of experimental therapeutics is often deemed successful via reductions in collagen deposition and expression of profibrotic genes in the lung. However, in clinical studies, improvements in lung function are primarily used to gauge the success of therapeutics directed towards IPF. Therefore, we examined whether changes in respiratory system mechanics in the early stages of an experimental model of lung fibrosis can be used to refine drug discovery approaches for IPF. C57BL/6J mice were administered bleomycin (BLM) or a vehicle control i.p. twice a week for 4 weeks. At 7, 14, 21, 28 and 33 days into the BLM treatment regimen, indices of respiratory system mechanics and pressure-volume relationships were measured. Concomitant with these measurements, histological and gene analyses relevant to lung fibrosis were performed. Alterations in respiratory system mechanics and pressure-volume relationships were observed as early as 7 days after the start of BLM administration. Changes in respiratory system mechanics preceded the appearance of histological and molecular indices of lung fibrosis. Administration of BLM leads to early changes in respiratory system mechanics that coincide with the appearance of representative histological and molecular indices of lung fibrosis. Consequently, these data suggest that dampening the early changes in respiratory system mechanics might be used to assess the effectiveness of experimental therapeutics in preclinical animal models of lung fibrosis.

Characterization of reactive oxygen species in diaphragm

Reactive oxygen species (ROS) exist as natural mediators of metabolism to maintain cellular homeostasis. However, ROS production may significantly increase in response to environmental stressors, resulting in extensive cellular damage. Although several potential sources of increased ROS have been proposed, exact mechanisms of their generation have not been completely elucidated. This is particularly true for diaphragmatic skeletal muscle, the key muscle used for respiration. Several experimental models have focused on detection of ROS generation in rodent diaphragm tissue under stressful conditions, including hypoxia, exercise, and heat, as well as ROS formation in single myofibres. Identification methods include direct detection of ROS with confocal or fluorescent microscopy and indirect detection of ROS through end product analysis. This article explores implications of ROS generation and oxidative stress, and also evaluates potential mechanisms of cellular ROS formation in diaphragmatic skeletal muscle.