The transcription repressor Bach2 is required for maintaining the B-1 cell population by regulating self-renewal

B-1 cells are a distinct lineage of tissue-resident B cells with crucial roles in innate immunity and tissue homeostasis. Mature B-1 cell pools are mostly maintained by self-renewal in their peripheral niches, in a process that is largely uncharacterized. Here, we investigated the role of the transc...

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Main Authors: Seung-Gen Oh, Jeonghyun Noh, Eunkyeong Jang, Jeehee Youn
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-03-01
Series:Frontiers in Immunology
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Online Access:https://www.frontiersin.org/articles/10.3389/fimmu.2025.1553089/full
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Summary:B-1 cells are a distinct lineage of tissue-resident B cells with crucial roles in innate immunity and tissue homeostasis. Mature B-1 cell pools are mostly maintained by self-renewal in their peripheral niches, in a process that is largely uncharacterized. Here, we investigated the role of the transcription repressor Bach2 in maintaining the B-1 cell pool. We found that B-1 cell numbers and antibody responses were dramatically reduced in adult mice bearing a B cell-specific Bach2 deletion, although the proportions of B-1 progenitors in early neonatal life were unaffected. Cells taken from the fetal liver or bone marrow of Bach2-deleted mice were defective in reconstituting the B-1 cell pool in the peritonea of Rag2-/- hosts, and peritoneal B-1 cell transplants from adult Bach2-deleted mice failed to sustain their numbers in the host’s peritoneum. The mutant B-1 cells proliferated normally in vivo but were more apoptotic. They also expressed the reduced level of the self-renewal factor Bmi1. These results indicate that Bach2 deficiency does not affect the development of B-1 progenitors in fetal liver and bone marrow but impairs the self-renewal of mature B-1 cells in peripheral tissues, which is caused by increased apoptosis. Thus, this study suggests that a cell-autonomous function of Bach2 is crucial for maintaining a stable population size of B-1 cells in their peripheral niches.
ISSN:1664-3224