Women and Lung Disease. Sex Differences and Global Health Disparities.

There is growing evidence that a number of pulmonary diseases affect women differently and with a greater degree of severity than men. The causes for such sex disparity is the focus of this Blue Conference Perspective review, which explores basic cellular and molecular mechanisms, life stages, and clinical outcomes based on environmental, sociocultural, occupational, and infectious scenarios, as well as medical health beliefs. Owing to the breadth of issues related to women and lung disease, we present examples of both basic and clinical concepts that may be the cause for pulmonary disease disparity in women. These examples include those diseases that predominantly affect women, as well as the rising incidence among women for diseases traditionally occurring in men, such as chronic obstructive pulmonary disease. Sociocultural implications of pulmonary disease attributable to biomass burning and infectious diseases among women in low- to middle-income countries are reviewed, as are disparities in respiratory health among sexual minority women in high-income countries. The implications of the use of complementary and alternative medicine by women to influence respiratory disease are examined, and future directions for research on women and respiratory health are provided.

Airway hyperresponsiveness is associated with airway remodeling but not inflammation in aging Cav1-/- mice.

BACKGROUND: Airway inflammation and airway remodeling are the key contributors to airway hyperresponsiveness (AHR), a characteristic feature of asthma. Both processes are regulated by Transforming Growth Factor (TGF)-ß. Caveolin 1 (Cav1) is a membrane bound protein that binds to a variety of receptor and signaling proteins, including the TGF-ß receptors. We hypothesized that caveolin-1 deficiency promotes structural alterations of the airways that develop with age will predispose to an increased response to allergen challenge. METHODS: AHR was measured in Cav1-deficient and wild-type (WT) mice 1 to 12 months of age to examine the role of Cav1 in AHR and the relative contribution of inflammation and airway remodeling. AHR was then measured in Cav1-/- and WT mice after an ovalbumin-allergen challenge performed at either 2 months of age, when remodeling in Cav1-/- and WT mice was equivalent, and at 6 months of age, when the Cav1-/- mice had established airway remodeling. RESULTS: Cav1-/- mice developed increased thickness of the subepithelial layer and a correspondingly increased AHR as they aged. In addition, allergen-challenged Cav1-/- mice had an increase in AHR greater than WT mice that was largely independent of inflammation. Cav1-/- mice challenged at 6 months of age have decreased AHR compared to those challenged at 2 months with correspondingly decreased BAL IL-4 and IL-5 levels, inflammatory cell counts and percentage of eosinophils. In addition, in response to OVA challenge, the number of goblet cells and α-SMA positive cells in the airways were reduced with age in response to OVA challenge in contrast to an increased collagen deposition further enhanced in absence of Cav1. CONCLUSION: A lack of Cav1 contributed to the thickness of the subepithelial layer in mice as they aged resulting in an increase in AHR independent of inflammation, demonstrating the important contribution of airway structural changes to AHR. In addition, age in the Cav1-/- mice is a contributing factor to airway remodeling in the response to allergen challenge.

Secretion of leukotrienes by senescent lung fibroblasts promotes pulmonary fibrosis.

Accumulation of senescent cells is associated with the progression of pulmonary fibrosis, but mechanisms accounting for this linkage are not well understood. To explore this issue, we investigated whether a class of biologically active profibrotic lipids, the leukotrienes (LT), is part of the senescence-associated secretory phenotype. The analysis of conditioned medium (CM), lipid extracts, and gene expression of LT biosynthesis enzymes revealed that senescent cells secreted LT, regardless of the origin of the cells or the modality of senescence induction. The synthesis of LT was biphasic and followed by antifibrotic prostaglandin (PG) secretion. The LT-rich CM of senescent lung fibroblasts (IMR-90) induced profibrotic signaling in naive fibroblasts, which were abrogated by inhibitors of ALOX5, the principal enzyme in LT biosynthesis. The bleomycin-induced expression of genes encoding LT and PG synthases, level of cysteinyl LT in the bronchoalveolar lavage, and overall fibrosis were reduced upon senescent cell removal either in a genetic mouse model or after senolytic treatment. Quantification of ALOX5+ cells in lung explants obtained from idiopathic pulmonary fibrosis (IPF) patients indicated that half of these cells were also senescent (p16Ink4a+). Unlike human fibroblasts from unused donor lungs made senescent by irradiation, senescent IPF fibroblasts secreted LTs but failed to synthesize PGs. This study demonstrates for the first time to our knowledge that senescent cells secrete functional LTs, significantly contributing to the LT pool known to cause or exacerbate IPF.

A new approach for analyzing cellular infiltration during allergic airway inflammation.

A mouse model for allergic airway inflammation involving ovalbumin (OVA) sensitization and challenge has been developed that reproduces hallmark features of human asthma and has provided valuable insight into the mechanisms by which this disease occurs. Cellular infiltrate in lungs of mice used in this model have conventionally been evaluated using histological examination of tissue sections and light microscopic analysis of lung lavage samples. As an alternative or complementary approach for characterizing cellular infiltrate, we developed a multicolor fluorescence-activated cell sorter (FACS) method involving the simultaneous detection of seven different markers on lung cell suspensions: CD4, CD8, B220, CD11b, Gr-1, CD49b, and FcepsilonRI. Only some of these cell types increased in OVA-challenged mice compared to PBS controls, including the CD4(+), B220(+), CD11b(+), and FcepsilonRI(+) groups. We also examined subpopulations of cells for coexpression of these markers and dissected heterogeneous populations as further evaluation procedures to characterize the cellular infiltrate resulting from OVA challenge. Finally, we combined FACS with real-time PCR to analyze certain cell types in terms of mRNA levels for factors involved in asthma, including GATA-3 and IL-1beta. Overall, these FACS-based techniques provide a powerful approach for analyzing cellular profiles in lung tissue from mice used in the mouse model of asthma and may also prove valuable in evaluating cellular infiltrates for other models of inflammation and immune responses.

Myocardial tissue caveolae.

Caveolae and their coat proteins, caveolins (Cav), are cave-like invaginations found in the plasma membrane of a variety of cells. These unique vesicles and their coat proteins, Cavs, have diverse effects on endothelial function, nitric oxide synthesis regulation, signal transduction, cholesterol metabolism, and apoptosis. Animal studies in Cav knockout mice demonstrate the vital role of these structural proteins on endothelial and vascular function. Genetic studies have proposed that beside neoplasia, Cavs may play a role in the development of atherosclerosis, cardiomyopathy, long QT syndrome, pulmonary fibrosis, and muscular dystrophy. The role of Cav expression in atherosclerotic disease is poorly understood and remains controversial. Interestingly, there is emerging evidence between low Cav-1 levels and the vulnerable plaque, which could potentially identify Cav-1 as a novel plaque biomarker. Cavs, through intricate biochemical pathways involving endothelial nitric oxide synthase and mitogen-activated protein kinase, are known to affect the cardiovascular system at multiple levels. In the present review, we aim to highlight the nature and types of caveolae, caveolar signaling mechanisms and regulation, and the pathophysiology of Cavs as it pertains to the cardiovascular system. Ongoing research is needed to clarify the diagnostic and prognostic role of these novel proteins and to determine how the effects of Cavs can translate into clinical medicine.

Progressive hair loss and myocardial degeneration in rough coat mice: reduced lysyl oxidase-like (LOXL) in the skin and heart.

The rough coat (rc) is a spontaneous recessive mutation in mice. To identify the mutated gene, we have characterized the rc phenotype and initiated linkage mapping. The rc mice show growth retardation, cyclic and progressive hair loss, hyperplastic epidermis, abnormal hair follicles, cardiac muscle degeneration, and reduced amount of collagen and elastin in the skin and heart. The rc locus was mapped at 32.0 cM on chromosome 9, close to the loxl gene. Lysyl oxidase-like (LOXL) protein is a novel copper-containing amine oxidase that is required for the cross-linking of elastin and collagen in vitro. LOXL is expressed at high levels in the skin and heart, where the rc mice show strong phenotype. The expression pattern and the genetic proximity to rc suggested loxl as a potential candidate gene. In rc mice, the loxl mRNA was reduced in the skin and the LOXL protein in the heart, dermis, atrophic hair follicles, and sebaceous glands. No mutations, however, were identified within the coding region of loxl, and offspring from rc/rc and loxl null mice crossing were phenotypically normal. Based on these results, loxl appears non-allelic to rc. Heart- and skin-specific downregulation of LOXL in rc mice, however, may contribute to the extracellular matrix alterations and the rc phenotype.

Chronic and intermittent hypoxia differentially regulate left ventricular inflammatory and extracellular matrix responses.

We evaluated the left ventricle (LV) response to hypoxia by comparing male Sprague Dawley rats exposed for 7 days to normoxia (control; n=18), chronic sustained hypoxia (CSH; n=12) and chronic intermittent hypoxia (CIH; n=12). Out of the 168 inflammatory, extracellular matrix and adhesion molecule genes evaluated, Ltb, Cdh4, Col5a1, Ecm1, MMP-11 and TIMP-2 increased in the LV (range: 87-138%), whereas Tnfrsf1a decreased 27%, indicating an increase in inflammatory status with CSH (all P<0.05). CIH decreased Ltb, Spp1 and Ccl5 levels, indicating reduced inflammatory status. While Laminin ß2 gene levels increased 123%, MMP-9 and fibronectin gene levels both decreased 74% in CIH (all P<0.05). Right ventricle/body weight ratios increased in CSH (1.1±0.1 g g(-1)) compared with control (0.7±0.1 g g(-1)) and CIH (0.8±0.1 g g(-1); both P<0.05). Lung to body weight increased in CSH, while LV/body weight ratios were similar among all three groups. With CIH, myocyte cross sectional areas increased 25% and perivascular fibrosis increased 100% (both P<0.05). Gene changes were independent of global changes and were validated by protein levels. MMP-9 protein levels decreased 94% and fibronectin protein levels decreased 42% in CIH (both P<0.05). Consistent with a decreased inflammatory status, HIF-2α and eNOS protein levels were 36% and 44% decreased, respectively, in CIH (both P<0.05). In conclusion, our results indicate that following 7 days of hypoxia, inflammation increases in response to CSH and decreases in response to CIH. This report is the first to demonstrate specific and differential changes seen in the LV during chronic sustained and CIH.

A role for dietary selenium and selenoproteins in allergic airway inflammation.

Asthma is driven by allergic airway inflammation and involves increased levels of oxidative stress. This has led to speculation that antioxidants like selenium (Se) may play important roles in preventing or treating asthma. We fed diets containing low (0.08 parts per million), medium (0.25 parts per million), or high (2.7 parts per million) Se to female C57BL/6 mice and used an established OVA challenge protocol to determine the relationship between Se intake and the development of allergic airway inflammation. Results demonstrated that mice fed medium levels of Se had robust responses to OVA challenge in the lung as measured by lung cytokine levels, airway cellular infiltrate, eosinophilia, serum anti-OVA IgE, airway hyperreactivity, goblet cell hyperplasia, and phosphorylated STAT-6 levels in the lung. In contrast, responses to OVA challenge were less robust in mice fed low or high levels of Se. In particular, mice fed low Se chow showed significantly lower responses compared with mice fed medium Se chow for nearly all readouts. We also found that within the medium Se group the expression of lung glutathione peroxidase-1 and liver selenoprotein P were increased in OVA-challenged mice compared with PBS controls. These data suggest that Se intake and allergic airway inflammation are not related in a simple dose-response manner, which may explain the inconsistent results obtained from previous descriptive studies in humans. Also, our results suggest that certain selenoproteins may be induced in response to Ag challenges within the lung.