Early life thymectomy induces arterial dysfunction in mice.

Area of Science:

• Immunology
• Vascular Biology
• Aging Research

Background:

• Arterial aging involves increased stiffness and impaired dilation, with T cells implicated in age-related vascular dysfunction.
• Previous studies showed T cell accumulation in aged mouse aortas and mesenteric arteries, and their removal improved arterial function.

Purpose of the Study:

• To determine if an aged-like T cell phenotype, induced early in life, is sufficient to cause arterial dysfunction in young mice.
• To investigate the impact of early life thymectomy on T cell populations and arterial health.

Main Methods:

• Mice underwent thymectomy at three weeks of age or were left with intact thymus (controls).
• T cell phenotypes (CD4+, CD8+ memory, cytokine production) were analyzed in blood, aorta, and mesentery at 9 months.
• Arterial stiffness, aortic collagen deposition, and mesenteric artery endothelium-dependent dilation were assessed.

Main Results:

• Thymectomized mice showed increased CD4+ and CD8+ memory T cells and proinflammatory cytokine-producing T cells, mimicking aged mice.
• These T cell alterations were observed in blood, aorta, and mesentery.
• Thymectomized mice exhibited augmented large artery stiffness, increased aortic collagen, and impaired mesenteric artery dilation due to reduced nitric oxide bioavailability.

Conclusions:

• Early life thymectomy induces an aged-like T cell phenotype in young mice.
• This aged-like T cell phenotype alone is sufficient to cause significant arterial dysfunction, including stiffness and impaired vasodilation.
• These findings highlight the critical role of T cell aging in driving vascular aging.