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Updated: Jul 11, 2026
Mouse Model of Alloimmune-induced Vascular Rejection and Transplant Arteriosclerosis
Published on: May 17, 2015
Macrophage depletion suppresses cardiac allograft vasculopathy in mice
W H Kitchens1, C M Chase, S Uehara
1Division of Transplantation, Department of Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
Insights
Macrophages are key drivers of cardiac allograft vasculopathy (CAV), a common cause of transplant failure. Depleting these immune cells significantly reduced CAV development in a mouse model, highlighting their role in transplant rejection.
Area of Science:
- Immunology
- Transplantation Biology
- Vascular Biology
Background:
- Cardiac allograft vasculopathy (CAV) is a primary cause of late mortality after heart transplantation.
- The specific cell types responsible for initiating vascular damage in CAV remain incompletely understood.
- Macrophages are abundant in CAV lesions and possess the capacity to produce growth factors linked to neointimal proliferation.
Purpose of the Study:
- To investigate the role of macrophages as end-effector cells in the development of cardiac allograft vasculopathy (CAV).
- To determine if macrophage depletion can prevent or reduce CAV formation in a murine cardiac transplant model.
Main Methods:
- A murine heterotopic cardiac transplant model was utilized.
- Macrophage depletion was achieved using intraperitoneal carrageenan or intravenous gadolinium.
- Flow cytometry and NK cytotoxicity assays confirmed minimal impact on T, B, and NK cells.
- The development of CAV was assessed in treated and control groups.
Main Results:
- Carrageenan treatment resulted in 30-80% macrophage depletion and a 70% reduction in CAV development (p = 0.01).
- The degree of CAV reduction correlated directly with the extent of macrophage depletion.
- Inhibition of macrophage phagocytosis alone with gadolinium did not prevent CAV.
- These findings suggest macrophages are critical end-effectors in CAV pathogenesis.
Conclusions:
- Macrophages appear to be the crucial end-effector cells in a common pathway leading to CAV.
- Macrophage-mediated injury in CAV may be primarily driven by cytokine and growth factor production, rather than phagocytosis.
- These findings are independent of T-cell or B-cell alloreactivity and suggest targeted macrophage inhibition as a potential therapeutic strategy.
Abstract:
Cardiac allograft vasculopathy (CAV) is a major source of late posttransplant mortality. Although numerous cell types are implicated in the pathogenesis of CAV, it is unclear which cells actually induce the vascular damage that results in intimal proliferation. Because macrophages are abundant in CAV lesions and are capable of producing growth factors implicated in neointimal proliferation, they are leading end-effector candidates. Macrophages were depleted in a murine heterotopic cardiac transplant system known to develop fulminant CAV lesions. C57BL/6 hearts were transplanted into (C57BL/6 x BALB/c)F(1) recipients, which then received anti-macrophage therapy with intraperitoneal carrageenan or i.v. gadolinium. Intraperitoneal carrageenan treatment depleted macrophages by 30-80% with minimal effects upon T, B or NK cells as confirmed by flow cytometry and NK cytotoxicity assays. Carrageenan treatment led to a 70% reduction in the development of CAV, as compared to mock-treated controls (p = 0.01), which correlated with the degree of macrophage depletion. Inhibition of macrophage phagocytosis alone with gadolinium failed to prevent CAV. Macrophages may represent the end-effector cells in a final common pathway towards CAV independent of T-cell or B-cell alloreactivity and exert their injurious effects through mechanisms related to cytokine/growth factor production rather than phagocytosis.
