Clonal hematopoiesis driven by mutated DNMT3A promotes inflammatory bone loss

Area of Science:

• Hematology
• Immunology
• Genetics

Background:

• Clonal hematopoiesis of indeterminate potential (CHIP) involves aging-associated mutations in hematopoietic progenitors, leading to altered leukocytes.
• CHIP with DNMT3A mutations is associated with increased periodontitis and gingival inflammation in adults.

Purpose of the Study:

• To model DNMT3A-driven CHIP using mice with a heterozygous loss-of-function mutation (R878H) equivalent to human R882H.
• To investigate the impact of DNMT3A-driven CHIP on periodontitis, arthritis, and related inflammatory pathways.

Main Methods:

• Utilized mice with Dnmt3a^R878H/+ mutation for bone marrow transplantation.
• Assessed clonal expansion, osteoclastogenesis, inflammatory markers (IL-17), immune cell function (Tregs, neutrophils), and periodontitis/arthritis severity.
• Evaluated the effect of rapamycin treatment on CHIP and associated conditions.

Main Results:

• DNMT3A-driven CHIP led to clonal expansion of myeloid and lymphoid cells, increased osteoclast precursors, and promoted periodontitis and arthritis in mice.
• CHIP induced IL-17-dependent inflammation, heightened neutrophil responses, and impaired regulatory T cell function.
• Rapamycin treatment suppressed DNMT3A-driven CHIP, periodontitis, and related inflammatory bone loss.

Conclusions:

• DNMT3A-driven CHIP is a treatable state of maladaptive hematopoiesis that promotes inflammatory bone loss through enhanced osteoclastogenesis and immune dysregulation.
• Targeting CHIP and its downstream inflammatory effects offers a potential therapeutic strategy for periodontitis and related inflammatory conditions.