237: M2 macrophages: Keyplayers in the fibro-proliferative response in cardiac allograft vasculopathy

Extensive Cardiac Allograft Vasculitis and Concurrent Fat Necrosis 6 Years After Orthotopic Heart Transplantation

“…8,9 M2, but not M1, macrophages have recently been shown to be present in the luminal layer of CAV lesions by gene expression studies. 6 By immunohistochemistry, the macrophages in our case were SRA ϩ and iNOS Ϫ , indicating they were of the M2 phenotype. These M2 macrophages were associated with medial destruction rather than intimal thickening.…”

“…Two recent studies have shown that the macrophage phenotype differs between these entities. 6,7 The M1 phenotype is characterized by macrophages that mediate inflammatory responses. These cells generate high levels of iNOS.…”

Cardiac Allograft Vasculopathy: A Donor or Recipient Induced Pathology?

“…The secretion of cytokines like IFN-γ and transforming growth factor-β (TGF-β) by T-lymphocytes leads to the activation of macrophages and fibroblasts respectively [ 25 , 59 ]. It has been shown that especially recipient-derived macrophages type 2 (M2) are increased in the neo-intima of CAV arteries [ 60 , 61 ]. These macrophages are involved in tissue remodeling and matrix deposition and play an important role in the development of fibrotic lesions [ 60 , 62 ].…”

“…It has been shown that especially recipient-derived macrophages type 2 (M2) are increased in the neo-intima of CAV arteries [ 60 , 61 ]. These macrophages are involved in tissue remodeling and matrix deposition and play an important role in the development of fibrotic lesions [ 60 , 62 ]. They are known to infiltrate the allograft and produce growth factors, such as TGF-β, which increases neo-intimal proliferation [ 61 ].…”