phenotyping-mouse-pulmonary-function-vivo-with-lung-diffusing

Phenotyping Mouse Pulmonary Function <em>In Vivo</em> with the Lung Diffusing Capacity

The mouse is now the primary animal used to model a variety of lung diseases. To study the mechanisms that underlie such pathologies, phenotypic methods ...

measurement-of-the-pressure-volume-curve-in-mouse-lungs

Measurement of the Pressure-volume Curve in Mouse Lungs

In recent decades the mouse has become the primary animal model of a variety of lung diseases. In models of emphysema or fibrosis, the essential ...

Lung parenchyma is normally considered to be isotropic, that is, its properties do not depend upon specific preferential directions. The assumption of isotropy is important for both modeling of lung mechanical properties and quantitative histologic measurements. This assumption, however, has not been previously examined at the microscopic level, in part because of the difficulty in large lungs of obtaining sufficient numbers of small samples of tissue while maintaining the spatial orientation. In the mouse, however, this difficulty is minimized. We evaluated the parenchymal isotropy in mouse lungs by quantifying the mean airspace chord lengths (Lm) from high-resolution histology of complete sections surrounded by an intact continuous visceral pleural membrane. We partitioned this lung into 5 isolated regions, defined by the distance from the visceral pleura. To further evaluate the isotropy, we also measured Lm in two orthogonal spatial directions with respect to the section orientation, and varied the sample line spacing from 3 to 280 microm. Results show a striking degree of parenchymal anisotropy in normal mouse lungs. The Lm was significantly greater when grid lines were parallel to the ventral-dorsal axis of the tissue. In addition the Lm was significantly smaller within 300 microm of the visceral pleura. Whether this anisotropy results from intrinsic structural factors or from nonuniform shrinkage during conventional tissue processing is uncertain, but it should be considered when interpreting quantitative morphometric measurements made in the mouse lung.

Anisotropic nature of mouse lung parenchyma.

Approximately 3 billion people-half the worldwide population-are exposed to extremely high concentrations of household air pollution due to the burning of biomass fuels on inefficient cookstoves, accounting for 4 million annual deaths globally. Yet, our understanding of the pulmonary responses to household air pollution exposure and the underlying molecular and cellular events is limited. The two most prevalent biomass fuels in India are wood and cow dung, and typical 24-hour mean particulate matter (PM) concentrations in homes that use these fuels are 300 to 5,000 μg/m(3). We dissected the mechanisms of pulmonary responses in mice after acute or subchronic exposure to wood or cow dung PM collected from rural Indian homes during biomass cooking. Acute exposures resulted in robust proinflammatory cytokine production, neutrophilic inflammation, airway resistance, and hyperresponsiveness, all of which were significantly higher in mice exposed to PM from cow dung. On the contrary, subchronic exposures induced eosinophilic inflammation, PM-specific antibody responses, and alveolar destruction that was highest in wood PM-exposed mice. To understand the molecular pathways that trigger biomass PM-induced inflammation, we exposed Toll-like receptor (TLR)2-, TLR3-, TLR4-, TLR5-, and IL-1R-deficient mice to PM and found that IL-1R, TLR4, and TLR2 are the predominant receptors that elicit inflammatory responses via MyD88 in mice exposed to wood or cow dung PM. In conclusion, this study demonstrates that subchronic exposure to PM collected from households burning biomass fuel elicits a persistent pulmonary inflammation largely through activation of TLR and IL-1R pathways, which could increase the risk for chronic respiratory diseases.

Source of biomass cooking fuel determines pulmonary response to household air pollution.

Cigarette smoke (CS) is the most common cause of chronic obstructive pulmonary diseases (COPD), including emphysema. CS exposure impacts all cell types within the airways and lung parenchyma, causing alveolar tissue destruction through four mechanisms: (1) oxidative stress; (2) inflammation; (3) protease-induced degradation of the extracellular matrix; and (4) enhanced alveolar epithelial and endothelial cell (EC) apoptosis. Studies in human pulmonary ECs demonstrate that macrophage migration inhibitory factor (MIF) antagonizes CS-induced apoptosis. Here, we used human microvascular ECs, an animal model of emphysema (mice challenged with chronic CS), and patient serum samples to address both the capacity of CS to alter MIF expression and the effects of MIF on disease severity. We demonstrate significantly reduced serum MIF levels in patients with COPD. In the murine model, chronic CS exposure resulted in decreased MIF mRNA and protein expression in the intact lung. MIF deficiency (Mif(-/-)) potentiated the toxicity of CS exposure in vivo via increased apoptosis of ECs, resulting in enhanced CS-induced tissue remodeling. This was linked to MIF's capacity to protect against double-stranded DNA damage and suppress p53 expression. Taken together, MIF appears to antagonize CS-induced toxicity in the lung and resultant emphysematous tissue remodeling by suppressing EC DNA damage and controlling p53-mediated apoptosis, highlighting a critical role of MIF in EC homeostasis within the lung.

ArticleTotal : 2	Year
Publication title Cited by 16	2015
Publication title Cited by 47	2015

Article	Year
Anisotropic nature of mouse lung parenchyma. Annals of biomedical engineering\| PubMed ID: 18633711	2008
Source of biomass cooking fuel determines pulmonary response to household air pollution. American journal of respiratory cell and molecular biology\| PubMed ID: 24102120	2014
Macrophage migration inhibitory factor is a novel determinant of cigarette smoke-induced lung damage. American journal of respiratory cell and molecular biology\| PubMed ID: 24490973	2014

Jonathan Fallica

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