Identifying Targets for COPD Treatment Through Gene Expression Analyses

Despite the status of chronic obstructive pulmonary disease (COPD) as a major global health problem, no currently available therapies can limit COPD progression. Therefore, an urgent need exists for the development of new and effective treatments for COPD. An improved understanding in the molecular pathogenesis of COPD can potentially identify molecular targets to facilitate the development of new therapeutic modalities. Among the best approaches for understanding the molecular basis of COPD include gene expression profiling techniques, such as serial analysis of gene expression or microarrays. Using these methods, recent studies have mapped comparative gene expression profiles of lung tissues from patients with different stages of COPD relative to healthy smokers or non-smokers. Such studies have revealed a number of differentially-regulated genes associated with COPD progression, which include genes involved in the regulation of inflammation, extracellular matrix, cytokines, chemokines, apoptosis, and stress responses. These studies have shed new light on the molecular mechanisms of COPD, and suggest novel targets for clinical treatments

Mitochondrial Dysfunction Induces Formation of Lipid Droplets as a Generalized Response to Stress

Lipid droplet (LD) formation is a hallmark of cellular stress. Cells attempt to combat noxious stimuli by switching their metabolism from oxidative phosphorylation to glycolysis, sparing resources in LDs for generating cellular reducing power and for anabolic biosynthesis. Membrane phospholipids are also a source of LDs. To elucidate the formation of LDs, we exposed mice to hyperoxia, hypoxia, myocardial ischemia, and sepsis induced by cecal ligation and puncture (CLP). All the above-mentioned stressors enhanced the formation of LDs, as assessed by transmission electron microscopy, with severe mitochondrial swelling. Disruption of mitochondria by depleting mitochondrial DNA (ρ0 cells) significantly augmented the formation of LDs, causing transcriptional activation of fatty acid biosynthesis and metabolic reprogramming to glycolysis. Heme oxygenase (HO)-1 counteracts CLP-mediated septic shock in mouse models. In HO-1-deficient mice, LD formation was not observed upon CLP, but a concomitant decrease in “LD-decorating proteins” was observed, implying a link between LDs and cytoprotective activity. Collectively, LD biogenesis during stress can trigger adaptive LD formation, which is dependent on mitochondrial integrity and HO-1 activity; this may be a cellular survival strategy, apportioning energy-generating substrates to cellular defense

Identifying targets for COPD treatment through gene expression analyses

Despite the status of chronic obstructive pulmonary disease (COPD) as a major global health problem, no currently available therapies can limit COPD progression. Therefore, an urgent need exists for the development of new and effective treatments for COPD. An improved understanding in the molecular pathogenesis of COPD can potentially identify molecular targets to facilitate the development of new therapeutic modalities. Among the best approaches for understanding the molecular basis of COPD include gene expression profiling techniques, such as serial analysis of gene expression or microarrays. Using these methods, recent studies have mapped comparative gene expression profiles of lung tissues from patients with different stages of COPD relative to healthy smokers or non-smokers. Such studies have revealed a number of differentially-regulated genes associated with COPD progression, which include genes involved in the regulation of inflammation, extracellular matrix, cytokines, chemokines, apoptosis, and stress responses. These studies have shed new light on the molecular mechanisms of COPD, and suggest novel targets for clinical treatments

Carbon monoxide inhibits Fas activating antibody-induced apoptosis in endothelial cells

<p>Abstract</p> <p>Background</p> <p>The extrinsic apoptotic pathway initiates when a death ligand, such as the Fas ligand, interacts with its cell surface receptor (<it>ie</it>., Fas/CD95), forming a death-inducing signaling complex (DISC). The Fas-dependent apoptotic pathway has been implicated in several models of lung or vascular injury. Carbon monoxide, an enzymatic product of heme oxygenase-1, exerts antiapoptotic effects at low concentration <it>in vitro </it>and <it>in vivo</it>.</p> <p>Methods</p> <p>Using mouse lung endothelial cells (MLEC), we examined the antiapoptotic potential of carbon monoxide against apoptosis induced by the Fas/CD95-activating antibody (Jo2). Carbon monoxide was applied to cell cultures <it>in vitro</it>. The expression and/or activation of apoptosis-related proteins and signaling intermediates were determined using Western Immunoblot and co-immunoprecipitation assays. Cell death was monitored by lactate dehydrogenase (LDH) release assays. Statistical significance was determined by student T-test and a value of <it>P </it>< 0.05 was considered significant.</p> <p>Results</p> <p>Treatment of MLEC with Fas-activating antibody (Jo2) induced cell death associated with the formation of the DISC, and activation of caspases (-8, -9, and -3), as well as the pro-apoptotic Bcl-2 family protein Bax. Exposure of MLEC to carbon monoxide inhibited Jo2-induced cell death, which correlated with the inhibition of DISC formation, cleavage of caspases-8, -9, and -3, and Bax activation. Carbon monoxide inhibited the phosphorylation of the Fas-associated death domain-containing protein, as well as its association with the DISC. Furthermore, carbon monoxide induced the expression of the antiapoptotic protein FLIP and increased its association with the DISC.</p> <p>CO-dependent cytoprotection against Fas mediated apoptosis in MLEC depended in part on activation of ERK1/2-dependent signaling.</p> <p>Conclusions</p> <p>Carbon monoxide has been proposed as a potential therapy for lung and other diseases based in part on its antiapoptotic effects in endothelial cells. In vitro, carbon monoxide may inhibit both Fas/caspase-8 and Bax-dependent apoptotic signaling pathways induced by Fas-activating antibody in endothelial cells. Strategies to block Fas-dependent apoptotic pathways may be useful in development of therapies for lung or vascular disorders.</p

Caveolin-1: a critical regulator of lung fibrosis in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive chronic disorder characterized by activation of fibroblasts and overproduction of extracellular matrix (ECM). Caveolin-1 (cav-1), a principal component of caveolae, has been implicated in the regulation of numerous signaling pathways and biological processes. We observed marked reduction of cav-1 expression in lung tissues and in primary pulmonary fibroblasts from IPF patients compared with controls. We also demonstrated that cav-1 markedly ameliorated bleomycin (BLM)-induced pulmonary fibrosis, as indicated by histological analysis, hydroxyproline content, and immunoblot analysis. Additionally, transforming growth factor β1 (TGF-β1), the well-known profibrotic cytokine, decreased cav-1 expression in human pulmonary fibroblasts. cav-1 was able to suppress TGF-β1–induced ECM production in cultured fibroblasts through the regulation of the c-Jun N-terminal kinase (JNK) pathway. Interestingly, highly activated JNK was detected in IPF- and BLM-instilled lung tissue samples, which was dramatically suppressed by ad–cav-1 infection. Moreover, JNK1-null fibroblasts showed reduced smad signaling cascades, mimicking the effects of cav-1. This study indicates a pivotal role for cav-1 in ECM regulation and suggests a novel therapeutic target for patients with pulmonary fibrosis

Egr-1 Regulates Autophagy in Cigarette Smoke-Induced Chronic Obstructive Pulmonary Disease

Background: Chronic obstructive pulmonary disease (COPD) is a progressive lung disease characterized by abnormal cellular responses to cigarette smoke, resulting in tissue destruction and airflow limitation. Autophagy is a degradative process involving lysosomal turnover of cellular components, though its role in human diseases remains unclear. Methodology and Principal Findings: Increased autophagy was observed in lung tissue from COPD patients, as indicated by electron microscopic analysis, as well as by increased activation of autophagic proteins (microtubule-associated protein-1 light chain-3b, LC3B, Atg4, Atg5/12, Atg.7). Cigarette smoke extract (CSE) is an established model for studying the effects of cigarette smoke exposure in vitro. In human pulmonary epithelial cells, exposure to CSE or histone deacetylase (HDAC) inhibitor rapidly induced autophagy. CSE decreased HDAC activity, resulting in increased binding of early growth response-1 (Egr-1) and E2F factors to the autophagy gene LC3B promoter, and increased LC3B expression. Knockdown of E2F-4 or Egr-1 inhibited CSE-induced LC3B expression. Knockdown of Egr-1 also inhibited the expression of Atg4B, a critical factor for LC3B conversion. Inhibition of autophagy by LC3B-knockdown protected epithelial cells from CSE-induced apoptosis. Egr-1-1- mice, which displayed basal airspace enlargement, resisted cigarette-smoke induced autophagy, apoptosis, and emphysema. Conclusions: We demonstrate a critical role for Egr-1 in promoting autophagy and apoptosis in response to cigarette smoke exposure in vitro and in vivo. The induction of autophagy at early stages of COPD progression suggests novel therapeutic targets for the treatment of cigarette smoke induced lung injury. © 2008 Chen et al

Caveolin-1 Confers Antiinflammatory Effects in Murine Macrophages via the MKK3/p38 MAPK Pathway

Caveolin-1 has been reported to regulate apoptosis, lipid metabolism, and endocytosis in macrophages. In the present study, we demonstrate that caveolin-1 can act as a potent immunomodulatory molecule. We first observed caveolin-1 expression in murine alveolar macrophages by Western blotting and immunofluorescence microscopy. Loss-of-function experiments using small interfering RNA showed that downregulating caveolin-1 expression in murine alveolar and peritoneal macrophages increased LPS-induced proinflammatory cytokine TNF-α and IL-6 production but decreased anti-inflammatory cytokine IL-10 production. Gain-of-function experiments demonstrated that overexpression of caveolin-1 in RAW264.7 cells decreased LPS-induced TNF-α and IL-6 production and augmented IL-10 production. p38 mitogen-activated protein kinase (MAPK) phosphorylation was increased by overexpressing caveolin-1 in RAW264.7 cells, whereas c-Jun N-terminal kinase, extracellular signal-regulated kinase MAPK, and Akt phosphorylation were inhibited. The antiinflammatory modulation of LPS-induced cytokine production by caveolin-1 was significantly abrogated by the administration of p38 inhibitor SB203580 in RAW264.7 cells. Peritoneal macrophages isolated from MKK3 null mice did not demonstrate any modulation of LPS-induced cytokine production by caveolin-1. LPS-induced activation of NF-κB and AP-1 determined by electrophoretic mobility shift assay were significantly reduced by overexpressing caveolin-1 in RAW264.7 cells. The reductions were attenuated by the administration of p38 inhibitor SB203580. Taken together, our data suggest that caveolin-1 acts as a potent immunomodulatory effecter molecule in immune cells and that the regulation of LPS-induced cytokine production by caveolin-1 involves the MKK3/p38 MAPK pathway