Idiopathic pulmonary fibrosis (IPF) is an aging‐associated disease with poor prognosis. Currently, there are no effective drugs for preventing the disease process. The mechanisms underlying the role of alveolar epithelial cell (AEC) senescence in the pathogenesis of IPF remain poorly understood. We aimed to explore whether PTEN/NF‐κB activated AEC senescence thus resulting in lung fibrosis. First, we investigated the association between the activation of PTEN/NF‐κB and cellular senescence in lung tissues from IPF patients. As a result, decreased PTEN, activated NF‐κB and increased senescent markers (P21WAF1, P16ink4a, and SA‐β‐gal) were found in AECs in fibrotic lung tissues detected by immunohistochemistry (IHC) and immunofluorescence (IF). In vitro experiments showed increased expression levels of senescent markers and augmented senescence‐associated secretory phenotype (SASP) in AECs treated with bleomycin (Blm); however, PTEN was reduced significantly following IκB, IKK, and NF‐κB activation after stimulation with Blm in AECs. AEC senescence was accelerated by PTEN knockdown, whereas senescence was reversed via NF‐κB knockdown and the pharmacological inhibition (BMS‐345541) of the NF‐κB pathway. Interestingly, we observed increased collagen deposition in fibroblasts cultured with the supernatants collected from senescent AECs. Conversely, the deposition of collagen in fibroblasts was reduced with exposure to the supernatants collected from NF‐κB knockdown AECs. These findings indicated that senescent AECs controlled by the PTEN/NF‐κB pathway facilitated collagen accumulation in fibroblasts, resulting in lung fibrosis. In conclusion, our study supports the notion that as an initial step in IPF, the senescence process in AECs may be a potential therapeutic target, and the PTEN/NF‐κB pathway may be a promising candidate for intervention.
Emerging evidences indicate that placenta plays a critical role in gestational diabetes mellitus (GDM). DNA methylation could be associated with altered placental development and functions. This study is to uncover the genome-wide DNA methylation patterns in this disorder. DNA methylation was measured at >385,000 CpG sites using methylated DNA immunoprecipitation (MeDIP) and a huamn CpG island plus promoter microarray. We totally identified 6,641 differentially methylated regions (DMRs) targeting 3,320 genes, of which 2,729 DMRs targeting 1,399 genes, showed significant hypermethylation in GDM relative to the controls, whereas 3,912 DMRs targeting 1,970 genes showed significant hypomethylation. Functional analysis divided these genes into different functional networks, which mainly involved in the pathways of cell growth and death regulation, immune and inflammatory response and nervous system development. In addition, the methylation profiles and expressions of 4 loci (RBP4, GLUT3, Resistin and PPARα) were validated by BSP for their higher log2 ratio and potential functions with energy metabolism. This study demonstrates aberrant patterns of DNA methylation in GDM which may be involved in the pathophysiology of GDM and reflect the fetal development. Future work will assess the potential prognostic and therapeutic value for these findings in GDM.
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