Project description:Regenerating new alveolar epithelium is essential for recovery from many lung diseases. This multi-cellular regenerative process occurs when type II alveolar pneumocytes (AT2), with support from mesenchymal niche cells, proliferate to generate more AT2 cells and transdifferentiate in type I pneumocytes. To elucidate how coordinated events between AT2 cells and mesenchyme restore alveolar epithelium we used unbiased genome-wide analysis of chromatin accessibility and gene expression in both cell types following acute lung injury. We observed that chromatin acessability in AT2 cells changes signficantly following acute lung injury. Newly accessible chromatin reveals new STAT3 binding motifs adjacent to genes that regulate essential regenerative pathways in AT2 cells. Restoration of alveolar structures following both sterile and infectious lung injuries was inhibited when STAT3 signaling was lost in AT2 cells. Single-cell transcriptome analysis of regenerating AT2 cells identified brain neurotrophic factor (Bdnf) as the sole STAT3 target gene whose chromatin becomes newly accessible in a regenerating population of AT2 cells. BDNF increased alveolar organoid size and forming efficiency in murine and human models. The receptor for BDNF, TrkB, is uniquely? expressed on mesenchymal alveolar niche cells (MANC). Exposure of BDNF to TrkB increases expression of fibroblast growth factor 7 (Fgf7), an essential regenerative cytokine, in MANCs. Blocking Bdnf signaling with a TrkB receptor antagonist abrogated murine and human alveolar organoid formation. Finally, a small molecule TrkB agonist improved functional and histological outcomes in vivo following sterile and infectious lung injuries. Collectively, these data highlight the biological and therapeutic importance of the Stat3-Bdnf-TrkB axis in orchestrating alveolar epithelial regeneration
Project description:Regenerating new alveolar epithelium is essential for recovery from many lung diseases. This multi-cellular regenerative process occurs when type II alveolar pneumocytes (AT2), with support from mesenchymal niche cells, proliferate to generate more AT2 cells and transdifferentiate in type I pneumocytes. To elucidate how coordinated events between AT2 cells and mesenchyme restore alveolar epithelium we used unbiased genome-wide analysis of chromatin accessibility and gene expression in both cell types following acute lung injury. We observed that chromatin acessability in AT2 cells changes signficantly following acute lung injury. Newly accessible chromatin reveals new STAT3 binding motifs adjacent to genes that regulate essential regenerative pathways in AT2 cells. Restoration of alveolar structures following both sterile and infectious lung injuries was inhibited when STAT3 signaling was lost in AT2 cells. Single-cell transcriptome analysis of regenerating AT2 cells identified brain neurotrophic factor (Bdnf) as the sole STAT3 target gene whose chromatin becomes newly accessible in a regenerating population of AT2 cells. BDNF increased alveolar organoid size and forming efficiency in murine and human models. The receptor for BDNF, TrkB, is uniquely? expressed on mesenchymal alveolar niche cells (MANC). Exposure of BDNF to TrkB increases expression of fibroblast growth factor 7 (Fgf7), an essential regenerative cytokine, in MANCs. Blocking Bdnf signaling with a TrkB receptor antagonist abrogated murine and human alveolar organoid formation. Finally, a small molecule TrkB agonist improved functional and histological outcomes in vivo following sterile and infectious lung injuries. Collectively, these data highlight the biological and therapeutic importance of the Stat3-Bdnf-TrkB axis in orchestrating alveolar epithelial regeneration
Project description:Alveolar epithelial regeneration is essential for recovery from devastating lung diseases. This process occurs when type II alveolar pneumocytes (AT2 cells) proliferate and transdifferentiate into type I alveolar pneumocytes (AT1 cells). We used genome-wide analysis of chromatin accessibility and gene expression following acute lung injury to elucidate repair mechanisms. AT2 chromatin accessibility changed substantially following injury to reveal STAT3 binding motifs adjacent to genes that regulate essential regenerative pathways. Single-cell transcriptome analysis identified brain-derived neurotrophic factor (Bdnf) as a STAT3 target gene with newly accessible chromatin in a unique population of regenerating AT2 cells. Furthermore, the BDNF receptor tropomyosin receptor kinase B (TrkB) was enriched on mesenchymal alveolar niche cells (MANCs). Loss or blockade of AT2-specific Stat3, Bdnf or mesenchyme-specific TrkB compromised repair and reduced Fgf7 expression by niche cells. A TrkB agonist improved outcomes in vivo following lung injury. These data highlight the biological and therapeutic importance of the STAT3-BDNF-TrkB axis in orchestrating alveolar epithelial regeneration.
Project description:BackgroundGastrodin (GAS), is a kind of phenolic compound extracted from the traditional Chinese herbal medicine Gastrodia elata Blume (GEB). This study was aimed at probing into the protective effect of GAS on peripheral nerve injury (PNI) and the underlying mechanism.MethodsA rat model with PNI was established, followed by intraperitoneal injection of GAS (20 mg/kg/day). Sciatic nerve function index (SFI) was used to analyze the function of sciatic nerve. The amplitude and latency of compound muscle action potential (CMAP) were examined by electrophysiology. Schwann cells (SCs) were isolated from fetal rats and treated with GAS 200 μg/mL, and H2O2-induced model of oxidative stress injury was established. EdU and Transwell assays were adopted to detect the viability and migration of SCs. Dual-luciferase reporter gene assays were applied to verify the binding site between miR-497 and brain-derived neurotrophic factor (BDNF) 3'UTR. MiR-497 expression was probed by quantitative real-time polymerase chain reaction (qRT-PCR). BDNF, neurofilament-200 (NF-200) and myelin basic protein (MBP) expression levels were detected by Western blotting. Malondialdehyde (MDA) content, superoxide dismutase (SOD) activity, glutathione content (GSH) and catalase (CAT) activity in SCs were also measured.ResultsGAS treatment could significantly increase the SFI and amplitude of CMAP, shorten the refractory period, and ameliorate muscle atrophy of the rats with PNI. GAS treatment could markedly restrain miR-497 expression and increase the expression levels of BDNF, NF-200 and MBP in SCs. BDNF was confirmed as the target of miR-497 and BDNF overexpression could reverse the impacts of miR-497 overexpression on the proliferation, migration, and oxidative stress response of SCs.ConclusionsGAS promotes the recovery of PNI via modulating miR-497 / BDNF axis and inhibiting oxidative stress.