Project description:Pulmonary hypertension (PH) is a life-threatening disease, characterized by excessive pulmonary vascular remodeling, leading to elevated pulmonary arterial pressure and right heart hypertrophy. PH is caused, among other factors, by chronic hypoxia, leading to hyper-proliferation of pulmonary arterial smooth muscle cells (PASMC) and apoptosis-resistant pulmonary microvascular endothelial cells (PMVEC). Upon re-exposure to normoxia, chronic hypoxia-induced PH in mice is reversible. In this study, we aim to identify novel candidate genes involved in pulmonary vascular remodeling specifically in the pulmonary vasculature.
Project description:Pulmonary arterial hypertension (PAH) is a chronic progressive disease with significant morbidity and mortality. The disease is characterized by vascular remodeling that includes increased muscularization of distal blood vessels and vessel stiffening associated with changes in extracellular matrix deposition. In humans, chronic hypoxia causes PAH, and hypoxia-induced rodent models of PAH have been used for years to study the disease. With the development of single-cell RNA sequencing technology, it is now possible to examine hypoxia-dependent transcriptional changes in vivo at a cell-specific level. In this study, we used single-cell RNA sequencing to compare lungs from wild-type mice exposed to hypoxia for 28 days to normoxia-treated control mice. We additionally examined mice deficient for Notch3, a smooth muscle-enriched gene linked to PAH. Data analysis revealed that hypoxia promoted cell number changes in immune and endothelial cell types in the lung, activated the innate immunity pathway, and resulted in specific changes in gene expression in vascular cells. Surprisingly, we found limited differences in lungs from mice deficient for Notch3 compared to wild-type controls. These findings provide novel insight into the effects of chronic hypoxia exposure on gene expression and cell phenotypes in vivo and identify unique changes to cells of the vasculature.
Project description:Pulmonary hypoxia is a common complication of chronic lung diseases leading to the development of pulmonary hypertension. The underlying sustained increase in vascular resistance in hypoxia is a response unique to the lung. Thus, we hypothesised that there are genes whose expression is altered selectively in the lung in response to alveolar hypoxia. Using a novel subtractive array strategy, we compared gene responses to hypoxia in primary human pulmonary microvascular endothelial cells to those in cardiac microvascular endothelium and identified genes selectively differentially regulated in the lung endothelium. Keywords: Time course, cell type comparison
Project description:Polymorphonuclear neutrophil (PMN) infiltration at inflammatory site plays a critical role in inflammation. PMN reverse migration (rM) describes the phenomenon that PMNs migrate away from inflammatory site back into the vasculature, and its role within inflammatory scenarios remains to be fully determined. This study aimed to investigate the mechanism underlying PMN rM and its role in inflammation. First, we demonstrated PMN rM in a mouse model of LPS-induced acute lung inflammation. By single-cell RNA sequencing (scRNA-seq), we demonstrated that reverse migrated (rM-ed) PMNs in blood expressed high level of immuneresponsive gene 1 (Irg1), the encoding gene of cis-aconitate decarboxylase (ACOD1).
Project description:Human embryos develop under physiological hypoxia, but how hypoxia directly affects human organogenesis remains unknown. We have investigated the effects of hypoxia on human lung epithelia using organoids. First trimester lung epithelial progenitors remain undifferentiated under normoxia, but initiate spontaneous differentiation towards multiple airway cell types, and inhibit alveolar differentiation under hypoxia. Genetic and chemical manipulation experiments showed that these effects were dependent on HIF (Hypoxia-Inducible Factor) activity, with HIF1α and HIF2α differentially regulating progenitor fate decisions. We identified the cell fate-determining transcription factors KLF4/KLF5 and ASCL1 as direct targets of the HIF pathway, promoting progenitor differentiation to basal and neuroendocrine cells respectively. Chronic hypoxia also induces transdifferentiation of human alveolar type 2 cells into airway cells via the HIF pathway, suggesting that the developmental response to hypoxia is conserved into adulthood and potentially contributes to chronic lung disease.
Project description:Hypoxia can result in tissue dysfunction, metabolic alterations, and structural damage within the pulmonary tissue, thereby impacting lung ventilation and air exchange. The identification of Hypoxia-inducible factor (Hif) 1α as a pivotal mediator in the inflammatory cascade subsequent to hypoxia induction has been established. However, the mechanism remains elusive. To delve deeper into this phenomenon, we have developed a murine model of sustained hypoxia and utilized nanocarriers for the delivery of lentivirus Hif-1α for knockdown purposes. Our findings suggest that under conditions of sustained hypoxia, knockdown of Hif-1α effectively ameliorated SpO2 levels and attenuated lung injury in our murine model. We observed that Hif-1α-mediated Histone Lactylation was evident in the lungs exposed to sustained hypoxia. Through RNA-seq and ChIP-seq profiling, we determined that upregulation of Hif-1α expression in sustained hypoxic lung tissue is essential for inducing lactylation enrichment of inflammatory response genes. Furthermore, knockdown of Hif-1α returned to normal inflammatory cytokines (e.g. TNF-α, IL-6 and IL-1β). Analysis of plasma metabolites from individuals experiencing restrictive/ obstructive lung disease revealed a significant enrichment of the Warburg effect within the sustained hypoxic group. Thus, our study provides compelling evidence supporting the notion that targeting Hif-1α-mediated histone lactylation may represent a promising therapeutic strategy for managing sustained hypoxia-induced lung injury.
Project description:Tumor vasculature are structurally chaotic and functionally inefficient. Restoring aberrant tumor blood vessels, or “normalize” the tumor vasculature can alleviate hypoxia and enhance intra-tumoral drug delivery. However, identifying tumor vascular normalizing drugs are currently hampered by an absence of efficient screening platform. We aimed to develop a robust method to visualize, digitalize and evaluate the structural and functional changes of tumor vasculature in batch: zebrafish functional xenograft vasculature platform (zFXVP). As proof of principle, we applied zFXVP to a small compound library which has been implicated in affecting the morphology of tumor vasculature. zFXVP identified PF-502 as a durable tumor vascular normalization agent. Further molecular analysis using RNA-Seq, pharmaceutical inhibition and gene knockout indicate PF-502 can induce endothelial cell cycle arrest and simplify redundant tumor vasculature by blocking PI3K/mTOR signaling and stabilize the vessel lumen and stimulate the blood function by activating Notch1 signaling with mediating S3 cleavage. Last, in mouse tumor xenograft model, PF-502 reproduced a potent vascular normalizing effect at a sub MTD (maximum tolerated dose) and showed its ability to improve intra-tumoral drug delivery and synergize chemotherapy, which confirms the reliability of zFXVP and implicates the potential application of PF-502 in clinical practice as an adjuvant vascular normalization drug.
Project description:Here we investigated the protein composition of the main pulmonary artery (MPA), distal pulmonary arteries (DPA) distal whole lung (DWL) of early stage hypoxia (using a neonatal bovine calf model) and late stage hypoxia (using adult steers with hypoxia-induced PH) using high resolution mass spectrometry. Compartment-resolved analysis allowed for quantitative measurements of proteins from cellular, soluble ECM and insoluble ECM fractions
Project description:Human embryos develop under physiological hypoxia, but how hypoxia directly affects human organogenesis remains unknown. We have investigated the effects of hypoxia on human lung epithelia using organoids. First trimester lung epithelial progenitors remain undifferentiated under normoxia, but initiate spontaneous differentiation towards multiple airway cell types, and inhibit alveolar differentiation under hypoxia. Genetic and chemical manipulation experiments showed that these effects were dependent on HIF (Hypoxia-Inducible Factor) activity, with HIF1α and HIF2α differentially regulating progenitor fate decisions. We identified the cell fate-determining transcription factors KLF4/KLF5 and ASCL1 as direct targets of the HIF pathway, promoting progenitor differentiation to basal and neuroendocrine cells respectively. Chronic hypoxia also induces transdifferentiation of human alveolar type 2 cells into airway cells via the HIF pathway, suggesting that the developmental response to hypoxia is conserved into adulthood and potentially contributes to chronic lung disease.