Dataset Information

Transcription repressor Bach2 is required for pulmonary surfactant homeostasis and alveolar macrophage function.

ABSTRACT: 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.

SUBMITTER: Nakamura A

PROVIDER: S-EPMC3804940 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Transcription repressor Bach2 is required for pulmonary surfactant homeostasis and alveolar macrophage function.

Nakamura Atsushi A Ebina-Shibuya Risa R Itoh-Nakadai Ari A Muto Akihiko A Shima Hiroki H Saigusa Daisuke D Aoki Junken J Ebina Masahito M Nukiwa Toshihiro T Igarashi Kazuhiko K

The Journal of experimental medicine 20131014 11

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) cell ...[more]

PMID: 24127487

Similar Datasets

Project description:Pulmonary Alveolar Proteinosis (PAP) patients exhibit an acquired deficiency of biologically active granulocyte-macrophage colony stimulating factor (GM-CSF) attributable to GM-CSF specific autoantibodies. PAP alveolar macrophages are foamy, lipid-filled cells with impaired surfactant clearance and markedly reduced expression of the transcription factor peroxisome proliferator-activated receptor gamma (PPAR?) and the PPAR?-regulated ATP binding cassette (ABC) lipid transporter, ABCG1. An open label proof of concept Phase II clinical trial was conducted in PAP patients using rituximab, a chimeric murine-human monoclonal antibody directed against B lymphocyte specific antigen CD20. Rituximab treatment decreased anti-GM-CSF antibody levels in bronchoalveolar lavage (BAL) fluid, and 7/9 patients completing the trial demonstrated clinical improvement as measured by arterial blood oxygenation.This study sought to determine whether rituximab therapy would restore lipid metabolism in PAP alveolar macrophages.BAL samples were collected from patients pre- and 6-months post-rituximab infusion for evaluation of mRNA and lipid changes.Mean PPAR? and ABCG1 mRNA expression increased 2.8 and 5.3-fold respectively (p???0.05) after treatment. Lysosomal phospholipase A2 (LPLA2) (a key enzyme in surfactant degradation) mRNA expression was severely deficient in PAP patients pre-treatment but increased 2.8-fold post-treatment. In supplemental animal studies, LPLA2 deficiency was verified in GM-CSF KO mice but was not present in macrophage-specific PPAR? KO mice compared to wild-type controls. Oil Red O intensity of PAP alveolar macrophages decreased after treatment, indicating reduced intracellular lipid while extracellular free cholesterol increased in BAL fluid. Furthermore, total protein and Surfactant protein A were significantly decreased in the BAL fluid post therapy.Reduction in GM-CSF autoantibodies by rituximab therapy improves alveolar macrophage lipid metabolism by increasing lipid transport and surfactant catabolism. Mechanisms may involve GM-CSF stimulation of alveolar macrophage ABCG1 and LPLA2 activities by distinct pathways.

Dataset Information

Transcription repressor Bach2 is required for pulmonary surfactant homeostasis and alveolar macrophage function.

Publications

Transcription repressor Bach2 is required for pulmonary surfactant homeostasis and alveolar macrophage function.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets