Project description:Pulmonary alveolar proteinosis (PAP) results from a dysfunction of alveolar macrophages (AMs), chiefly due to disruptions in the signaling of granulocyte macrophage colony-stimulating factor (GM-CSF). We found that mice deficient for the B lymphoid transcription repressor BTB and CNC homology 2 (Bach2) developed PAP-like accumulation of surfactant proteins in the lungs. Bach2 was expressed in AMs, and Bach2-deficient AMs showed alterations in lipid handling in comparison with wild-type (WT) cells. Although Bach2-deficient AMs showed a normal expression of the genes involved in the GM-CSF signaling, they showed an altered expression of the genes involved in chemotaxis, lipid metabolism, and alternative M2 macrophage activation with increased expression of Ym1 and arginase-1, and the M2 regulator Irf4. Peritoneal Bach2-deficient macrophages showed increased Ym1 expression when stimulated with interleukin-4. More eosinophils were present in the lung and peritoneal cavity of Bach2-deficient mice compared with WT mice. The PAP-like lesions in Bach2-deficient mice were relieved by WT bone marrow transplantation even after their development, confirming the hematopoietic origin of the lesions. These results indicate that Bach2 is required for the functional maturation of AMs and pulmonary homeostasis, independently of the GM-CSF signaling. WT (n=8) and Bach2KO (n=3) AMs. One expreriment was performed.
Project description:Pulmonary alveolar proteinosis (PAP) results from a dysfunction of alveolar macrophages (AMs), chiefly due to disruptions in the signaling of granulocyte macrophage colony-stimulating factor (GM-CSF). We found that mice deficient for the B lymphoid transcription repressor BTB and CNC homology 2 (Bach2) developed PAP-like accumulation of surfactant proteins in the lungs. Bach2 was expressed in AMs, and Bach2-deficient AMs showed alterations in lipid handling in comparison with wild-type (WT) cells. Although Bach2-deficient AMs showed a normal expression of the genes involved in the GM-CSF signaling, they showed an altered expression of the genes involved in chemotaxis, lipid metabolism, and alternative M2 macrophage activation with increased expression of Ym1 and arginase-1, and the M2 regulator Irf4. Peritoneal Bach2-deficient macrophages showed increased Ym1 expression when stimulated with interleukin-4. More eosinophils were present in the lung and peritoneal cavity of Bach2-deficient mice compared with WT mice. The PAP-like lesions in Bach2-deficient mice were relieved by WT bone marrow transplantation even after their development, confirming the hematopoietic origin of the lesions. These results indicate that Bach2 is required for the functional maturation of AMs and pulmonary homeostasis, independently of the GM-CSF signaling.
Project description:Background: Pulmonary alveolar proteinosis (PAP) is a rare disease showing excess accumulation of surfactant protein in the alveolar spaces. It chiefly results from a dysfunction of alveolar macrophages (AMs) due to a lack of granulocyte macrophage colony-stimulating factor (GM-CSF) signaling including the expression of PU.1. We previously reported that mice deficient for Bach2 developed PAP-like disease due to a defect of lipid handling by AMs. Recently, Bach1 and Bach2 have been reported to function redundantly in early B cell development. The aim of this study was to investigate the function of Bach1 and Bach2 in alveolar macrophage and lung homeostasis. Methods: We generated mice lacking both Bach1 and Bach2 (Bach1/2 DKO mice) and investigated their body weight and survival rate. Whole lungs of mice were observed with Hematoxylin and eosin (HE) stain when they were 8 or 12-13 weeks old. The expression of surface markers and the numbers of alveolar macrophages and eosinophils in BAL were analyzed by flow cytometry (FACS). We also analyzed tissue macrophages in bone marrow and spleen by FACS. We administered N-acetyl cysteine to mice from prenatal stage and observed lung pathology at 12 weeks. Result: Bach1/2 DKO mice showed a more rapid and severe PAP phenotype than Bach2-deficient mice (Bach2 KO mice), whereas Bach1-deficient mice (Bach1 KO mice) did not develop any pulmonary disease. AMs in Bach1/2 DKO mice showed a foamy appearance, suggesting a defect in lipid handling. In contrast, the numbers of bone marrow macrophages and red pulp macrophages were not affected in Bach1/2 DKO mice. The PAP-like disease in Bach1/2 DKO and Bach2 KO mice was not ameliorated by N-acetyl cysteine. Conclusion: We suggest that Bach1 and Bach2 work in a complementary manner for the normal function of AMs and the maintenance of surfactant homeostasis in the lungs. Oxidative stress may be involved in the process of PAP by inactivating Bach1 and Bach2.
Project description:Tissue resident macrophages show their specific function to maintain homeostasis in our body. Dysfunction of alveolar macrophages (AMs), which regulate the proper amount of surfactant protein, leads to the development of pulmonary alveolar proteinosis (PAP). Here we found that inflammation ruins the function of AMs and is one of the causes of secondary PAP. Inflammation leads to the loss of specific gene expression pattern of AMs and furthermore, it leads to gain the specific gene expression pattern of other tissue resident macrophages and DC lineage. We also found the critical roles for Bach2 expressed in AMs and T cells, whose expression is induced by IFNg released from T cells. Bach2 bounds to super-enhancer regions of the inflammatory genes of the myeloid lineage and represses excess inflammation in lungs. Our results suggest that Bach2 function among several cell lineages to modify the inflammation, maintaining homeostasis in lungs.
Project description:Macrophages are central in regulating iron homeostasis. Transcription repressor Bach2 regulates by heme. Here we investigated the relationship between heme-regulated Bach2 and macrophage in bone marrow. We identified RFP-positive and negative macrophage were in bone marrow. We found that RFP-positive macrophage related with iron-heme homeostasis maintenance and RPF-negative population related with immune response. In RFP positive macrophage, we also found the lysosomal heme transporter hrg-1 was Bach2 direct target gene. Our results suggest that the function of the bone marrow macrophage alters according to expression of Bach2.
Project description:Macrophages are central in regulating iron homeostasis. Transcription repressor Bach2 regulates by heme. Here we investigated the relationship between heme-regulated Bach2 and macrophage in spleen. We found that gene expression were not many change between WT and Bach2 knock out mice in red-pulp macrophage.Our results suggest that the function of the red-pulp macrophage is not dependent on according to expression of Bach2.
Project description:Double knockout of Bach1 and Bach2 reveals shared compensatory mechanisms in regulating alveolar macrophage function and lung surfactant homeostasis
Project description:Double knockout of Bach1 and Bach2 reveals shared compensatory mechanisms in regulating alveolar macrophage function and lung surfactant homeostasis [ChIP-Seq]
Project description:Sash1 acts as a scaffold in TLR4 signaling. We generated Sash1-/- mice, which die in the perinatal period due to respiratory distress. Constitutive or endothelial-restricted Sash1 loss leads to a reduction of surfactant-associated protein synthesis. We show that Sash1 interacts with β-arrestin 1 downstream of the TLR4 pathway to activate Akt and eNOS in microvascular endothelial cells. Generation of nitric oxide downstream of Sash1 in endothelial cells activated cGMP in adjacent alveolar type 2 cells to induce transcription of surfactant genes. Thus we identify a critical cell nonautonomous function for Sash1 in embryonic development in which endothelial Sash1 affects alveolar type 2 cells and promotes pulmonary surfactant production through nitric oxide signaling. Lack of pulmonary surfactant is a major cause of respiratory distress and mortality in preterm infants, and these findings identify the endothelium as a potential target for therapy.
Project description:Differential chromatin accessibility accompanies and mediates transcriptional control of diverse cell fates and their differentiation during embryogenesis. While the critical role of NKX2-1 and its transcritional targets in lung morphogenesis and pulmonary epithelial cell differentiation is increasingly known, mechanisms by which chromatin accessibility alters the epigenetic landscape to regulate NKX2-1 activites required for alveolar epithelial cell differentiation and function are not well understood. Herein, we demonstrate that the paird domain zinc finger transcriptional regulators PRDM3 and PRDM16 regulate chromatin accessibility required for NKX2-1 mediated AT1 and AT2 cell differentiation decisions during lung morphogenesis and for control of the induction of AT@ cell gene expression controlling alveolar function and ventilation at birth. PRDM3 and 16 were required for activation of AT2 cell-associated gene expression, enhancing chromatin accessibility at NKX2-1 transcriptional targets. NKX2-1, PRDM3, and PRDM16 bound together at cis-active DNA elements in AT2 and AT1 cell selective transcriptional target genes, including those critical for perinatal AT2 cell differentitaion, surfactant homeostasis, and innate host defense. Deletion of PRDM3/16 inhibited NKX2-1-dependent gene regulatory networks controlling surfactant lipid and protein production, resulting in respiratory failure at birth. NKX2-1-dependent regulation of alveolar epithelial cell differentiation is mediated by PRDM3/16.