Lung fibrosis involves the overexpression of ECM proteins, primarily collagen, by alpha-smooth muscle actin (ASMA)-positive cells. Caveolin-1 is a master regulator of collagen expression by cultured lung fibroblasts and of lung fibrosis in vivo. A peptide equivalent to the caveolin-1 scaffolding domain (CSD peptide) inhibits collagen and tenascin-C expression by normal lung fibroblasts (NLF) and fibroblasts from the fibrotic lungs of scleroderma patients (SLF). CSD peptide inhibits ASMA expression in SLF but not NLF. Similar inhibition of collagen, tenascin-C, and ASMA expression was also observed when caveolin-1 expression was upregulated using adenovirus. These observations suggest that the low caveolin-1 levels in SLF cause their overexpression of collagen, tenascin-C, and ASMA. In mechanistic studies, MEK, ERK, JNK, and Akt were hyperactivated in SLF, and CSD peptide inhibited their activation and altered their subcellular localization. These studies and experiments using kinase inhibitors suggest many differences between NLF and SLF in signaling cascades. To validate these data, we determined that the alterations in signaling molecule activation observed in SLF also occur in fibrotic lung tissue from scleroderma patients and in mice with bleomycin-induced lung fibrosis. Finally, we demonstrated that systemic administration of CSD peptide to bleomycin-treated mice blocks epithelial cell apoptosis, inflammatory cell infiltration, and changes in tissue morphology as well as signaling molecule activation and collagen, tenascin-C, and ASMA expression associated with lung fibrosis. CSD peptide may be a prototype for novel treatments for human lung fibrosis that act, in part, by inhibiting the expression of ASMA and ECM proteins.

Indium is a relatively rare element that has had limited use for decades as a metal, in alloys, and for electronics applications. During the past 15 years, global demand for indium has increased several-fold, driven by the novel use of indium-tin oxide (ITO) thin fi lms in the production of fl at-panel displays (such as liquid crystal displays [LCDs]), touch screens, and other electronic devices. 1,2 ITO is a sintered ceramic material typically consisting of 90% indium oxide (In 2 O 3 ) and 10% tin oxide (SnO 2 ). Exposures to indium metal and indium compounds (including indium hydroxide [In(OH) 3 ], indium oxide, and ITO) may occur during ITO production, ITO use for the creation of thin fi lms, and reclamation. The bulk of the ITO industry is located in Japan, with some activity in the United States, China, Taiwan, and South Korea. 3 As of May 2010, 10 clinical cases of lung disease in indium workers from three countries (Japan, United States, and China) had been reported. 2 Seven cases were described as interstitial lung disease (ILD) characterized by pulmonary fi brosis with or without emphysema. Three cases were described as pulmonary alveolar proteinosis (PAP). Individually, these 10 case reports left unclear why some workers developed ILD and others developed PAP, and the relationship, if any, between these distinct pulmonary disease processes.Background: Reports of pulmonary fi brosis, emphysema, and, more recently, pulmonary alveolar proteinosis (PAP) in indium workers suggested that workplace exposure to indium compounds caused several different lung diseases. Methods: To better understand the pathogenesis and natural history of indium lung disease, a detailed, systematic, multidisciplinary analysis of clinical, histopathologic, radiologic, and epidemiologic data for all reported cases and workplaces was undertaken. Results: Ten men (median age, 35 years) who produced, used, or reclaimed indium compounds were diagnosed with interstitial lung disease 4-13 years after fi rst exposure (n 5 7) or PAP 1-2 years after fi rst exposure (n 5 3). Common pulmonary histopathologic features in these patients included intraalveolar exudate typical of alveolar proteinosis (n 5 9), cholesterol clefts and granulomas (n 5 10), and fi brosis (n 5 9). Two patients with interstitial lung disease had pneumothoraces. Lung disease progressed following cessation of exposure in most patients and was fatal in two. Radiographic data revealed that two patients with PAP subsequently developed fi brosis and one also developed emphysematous changes. Epidemiologic investigations demonstrated the potential for exposure to respirable particles and an excess of lung abnormalities among coworkers. Conclusions: Occupational exposure to indium compounds was associated with PAP, cholesterol ester crystals and granulomas, pulmonary fi brosis, emphysema, and pneumothoraces. The available evidence suggests exposure to indium compounds causes a novel lung disease that may begin with PAP and progress to include fi brosis and emphysema, and, in som...

(KYJ) S U M M A R Y Sphingosine kinase 1 (SK1) is a key enzyme critical to the sphingolipid metabolic pathway responsible for catalyzing the formation of the bioactive lipid sphingosine-1-phosphate. SK1-mediated production of sphingosine-1-phosphate has been shown to stimulate such biological processes as cell growth, differentiation, migration, angiogenesis, and inhibition of apoptosis. In this study, cell type-specific immunolocalization of SK1 was examined in the bronchus/terminal bronchiole of the lung. Strong immunopositive staining was evident at the apical surface of pseudostratified epithelial cells of the bronchus and underlying smooth muscle cells, submucosal serous glands, immature chondrocytes, type II alveolar cells, foamy macrophages, endothelial cells of blood vessels, and neural bundles.

In an attempt to explain the much greater risk of respiratory cancer at the same cumulative exposure in asbestos textile workers in Charleston, South Carolina, than in Quebec miners and millers, both exposed to chrysotile from the same source, 161 lung tissue samples taken at necropsy from dead cohort members were analysed by transmission electron microscopy. Altogether 1828 chrysotile and 3270 tremolite fibres were identified; in both cohorts tremolite predominated and fibre dimensions were closely similar. Lung fibre concentrations were analysed statistically (a) in 32 paired subjects matched for duration ofemployment and time from last employment to death and (b) in 136 subjects stratified by the same time variables. Both analyses indicated that the Quebec/ Charleston ratios for chrysotile fibre concentration in lung tissue were even higher than the corresponding ratios of estimated exposure intensity (mpcf). After allowance for the fact that regression analyses suggested that the proportion oftremolite in dust was probably 2 5 times higher in Thetford Mines, Quebec, than in Charleston, the results from both matched pair and stratification analyses of tremolite fibre concentrations in lung were almost the same as for chrysotile. It is concluded that neither fibre dimensional differences nor errors in estimation of exposure can explain the higher risks of lung cancer observed in asbestos textile workers. The possible co-carcinogenic role of mineral oil used in the past in asbestos textile plants to control dust provides an alternative hypothesis deserving consideration. exposures of the past were seldom documented. This difficult exercise has been attempted in nine industrial populations.2 Among these were the chrysotile miners and millers of Quebec34 and the chrysotile textile workers of Charleston, South Carolina.5 Linear relations between excess mortality from respiratory cancer and cumulative exposure in these two populations (fig 1) illustrate the problem considered in the present report. In both cohorts cumulative exposures (mpcf.y) were calculated from impinger data, all that were available for the past. Cumulative exposures as high as 2000 mpcf.y were recorded in the Quebec cohort, 10 times higher overall than exposures in Charleston. Figure 1 shows that, for the same cumulative exposure, the risk of respiratory cancer was about 50 times higher in Charleston. These estimates of risk were essentially corroborated by independent studies in the Charleston plant' and in Quebec.9 Studies in two other textile plants, one in the United States and another in the United Kingdom, gave similar results.'1 "The large difference in risk between mining and 180

Activated fibroblasts, or myofibroblasts, are crucial players in tissue remodeling, wound healing, and various fibrotic disorders, including interstitial lung fibrosis associated with scleroderma. Here we characterize the signaling pathways in normal lung fibroblasts exposed to thrombin as they acquire two of the main features of myofibroblasts: smooth muscle (SM) alpha-actin organization and collagen gel contraction. Our results show that the small G protein Rho is involved in lung myofibroblast differentiation. Thrombin induces Rho-35S-labeled guanosine 5'-O-(3-thiotriphosphate) binding in a dose-dependent manner. It potently stimulates Rho activity in vivo and initiates protein kinase C (PKC)-epsilon-Rho complex formation. Toxin B, which inactivates Rho by ADP ribosylation, inhibits thrombin-induced SM alpha-actin organization, collagen gel contraction, and PKC-epsilon-SM alpha-actin and PKC-epsilon-RhoA coimmunoprecipitation. However, it has no effect on PKC-epsilon activation or translocation of PKC-epsilon to the membrane. Overexpression of constitutively active PKC-epsilon and constitutively active RhoA induces collagen gel contraction or SM alpha-actin organization, whereas, individually, they do not perform these functions. We therefore conclude that the contractile activity of myofibroblasts induced by thrombin is mediated via PKC-epsilon- and RhoA-dependent pathways and that activation of both of these molecules is required. We postulate that PKC-epsilon-RhoA complex formation is an early event in thrombin activation of lung fibroblasts, followed by PKC-epsilon-SM alpha-actin coimmunoprecipitation, which leads to the PKC-epsilon-RhoA-SM alpha-actin ternary complex formation.