GM-CSF contributes to aortic aneurysms resulting from SMAD3 deficiency

Area of Science:

• Vascular Biology
• Immunology
• Genetics

Background:

• Heterozygous loss-of-function mutations in SMAD3 cause aneurysm-osteoarthritis syndrome (AOS).
• The precise mechanisms underlying AOS pathogenesis remain incompletely understood.

Purpose of the Study:

• To investigate the role of SMAD3 deficiency in aneurysm development and identify underlying inflammatory pathways.
• To explore the potential involvement of specific cytokines, such as GM-CSF, in AOS.

Main Methods:

• Utilized Smad3-deficient mouse models (Smad3-/-) and bone marrow transplantation experiments.
• Investigated the role of CD4+ T cells, IFN-γ, IL-17, and GM-CSF in disease pathogenesis.
• Analyzed human aortic aneurysm specimens for inflammatory markers and cytokine expression.

Main Results:

• Smad3-deficient mice exhibited progressive aneurysms with inflammatory cell infiltration.
• CD4+ T cells from Smad3-/- mice induced aortitis, and GM-CSF promoted inflammatory monocyte accumulation.
• IFN-γ exacerbated, while IL-17 ameliorated, disease severity in Smad3+/- mice.
• Human AOS patients showed increased inflammation and GM-CSF expression in aortic tissues.

Conclusions:

• SMAD3 deficiency promotes aneurysm formation through T-cell mediated inflammation, with a critical role for GM-CSF.
• GM-CSF is a key mediator in the development of AOS and may represent a therapeutic target.
• These findings provide novel insights into the molecular mechanisms of AOS and identify potential therapeutic strategies.