These findings suggest that human airway epithelial cells express these serine proteases and that serine protease inhibitors, especially camostat, may reduce influenza viral replication and the resultant production of inflammatory cytokines possibly through inhibition of activities of these proteases.

BackgroundThe excess and persistent accumulation of fibroblasts due to aberrant tissue repair results in fibrotic diseases such as idiopathic pulmonary fibrosis. Recent reports have revealed significant changes in microRNAs during idiopathic pulmonary fibrosis and evidence in support of a role for microRNAs in myofibroblast differentiation and the epithelial-mesenchymal transition in the context of fibrosis. It has been reported that microRNA-21 is up-regulated in myofibroblasts during fibrosis and promotes transforming growth factor-beta signaling by inhibiting Smad7. However, expression changes in microRNA-21 and the role of microRNA-21 in epithelial-mesenchymal transition during lung fibrosis have not yet been defined.MethodsLungs from saline- or bleomycin-treated C57BL/6 J mice and lung specimens from patients with idiopathic pulmonary fibrosis were analyzed. Enzymatic digestions were performed to isolate single lung cells. Lung epithelial cells were isolated by flow cytometric cell sorting. The expression of microRNA-21 was analyzed using both quantitative PCR and in situ hybridization. To induce epithelial-mesenchymal transition in culture, isolated mouse lung alveolar type II cells were cultured on fibronectin-coated chamber slides in the presence of transforming growth factor-β, thus generating conditions that enhance epithelial-mesenchymal transition. To investigate the role of microRNA-21 in epithelial-mesenchymal transition, we transfected cells with a microRNA-21 inhibitor. Total RNA was isolated from the freshly isolated and cultured cells. MicroRNA-21, as well as mRNAs of genes that are markers of alveolar epithelial or mesenchymal cell differentiation, were quantified using quantitative PCR.ResultsThe lung epithelial cells isolated from the bleomycin-induced lung fibrosis model system had decreased expression of epithelial marker genes, whereas the expression of mesenchymal marker genes was increased. MicroRNA-21 was significantly upregulated in isolated lung epithelial cells during bleomycin-induced lung fibrosis and human idiopathic pulmonary fibrosis. MicroRNA-21 was also upregulated in the cultured alveolar epithelial cells under the conditions that enhance epithelial-mesenchymal transition. Exogenous administration of a microRNA-21 inhibitor prevented the increased expression of vimentin and alpha-smooth muscle actin in cultured primary mouse alveolar type II cells under culture conditions that induce epithelial-mesenchymal transition.ConclusionsOur experiments demonstrate that microRNA-21 is increased in lung epithelial cells during lung fibrosis and that it promotes epithelial-mesenchymal transition.

Circulating endothelial microparticles (EMPs) are membrane vesicles that are shed into the blood stream from activated or apoptotic endothelial cells. We previously reported that circulating EMP numbers significantly increased in stable chronic obstructive pulmonary disease (COPD) patients and during exacerbation compared with healthy control subjects. However, different types of circulating EMPs with distinct time profiles were detectable during exacerbations. We hypothesized that the released EMP subtypes correlated with differences in the inflammatory stimuli and the endothelial cell type. We compared the EMP subtypes from human aortic endothelial cells (Aortic ECs) and human lung microvascular endothelial cells (Pulmonary microvascular ECs) released in response to various stimuli, including proinflammatory cytokines (TNFα), oxidative stress (H2O2), and cigarette smoke extracts (CSE) in vitro. We defined circulating EMPs by the expression of endothelial antigens: CD144(+) MPs (VE-cadherin EMPs), CD31(+)/CD41(-) MPs (PECAM EMPs), CD62E(+) MPs (E-selectin EMPs), and CD146(+) MPs (MCAM EMPs). E-selectin EMPs were released from both pulmonary microvascular and aortic ECs in response to TNFα but not to H2O2 or CSE stimulation. The amount of MCAM EMPs released from pulmonary microvascular ECs differed significantly between the cells stimulated with H2O2 and those stimulated with CSE. VE-cadherin EMPs were only released from aortic ECs, whereas PECAM EMPs were released exclusively from pulmonary microvascular ECs. The EMP subtypes released differ in vitro among TNFα, H2O2, and CSE stimulation as well as between pulmonary microvascular and aortic ECs. The differences in circulating EMP subtypes may reflect a condition or site of endothelial injury and may serve as markers for endothelial damage in COPD patients.

Decreased expression of SFTPC by TGF-β1 treatment was restored by TSA via hyperacetylation of histone H4 in the promoter region. TSA partially attenuated pulmonary fibrosis and increased Sftpc mRNA in ATII. Our findings suggest that the epigenetic restoration of SP-C would be a therapeutic target for pulmonary fibrosis.

Exposure to environmental factors during fetal development may lead to epigenomic modifications in fetal germ cells, altering gene expression and promoting diseases in successive generations. In mouse, maternal exposure to di(2-ethylhexyl) phthalate (DEHP) is known to induce defects in spermatogenesis in successive generations, but the mechanism(s) of impaired spermatogenesis are unclear. Here, we showed that maternal DEHP exposure results in DNA hypermethylation of promoters of spermatogenesis-related genes in fetal testicular germ cells in F1 mice, and hypermethylation of Hist1h2ba, Sycp1, and Taf7l, which are crucial for spermatogenesis, persisted from fetal testicular cells to adult spermatogonia, resulting in the downregulation of expression of these genes. Forced methylation of these gene promoters silenced expression of these loci in a reporter assay. These results suggested that maternal DEHP exposure-induced hypermethylation of Hist1h2ba, Sycp1, and Taf7l results in downregulation of these genes in spermatogonia and subsequent defects in spermatogenesis, at least in the F1 generation.