Does Human Leukocyte Antigen-G (HLA-G) Play a Role in Immunte Modulation and Vasculopathy in Heart Transplantation?

HLA-G is a protein normally expressed during pregnancy, protecting the fetus from the maternal immune system. Previous studies have shown an association between HLA-G expression post-transplantation and lower incidences of organ rejection. To further examine this beneficial role, we conducted a prospective study following a cohort of heart transplant recipients for one year and measuring their plasma HLA-G levels at various time points. Preliminary analyses failed to reveal an association between HLA-G and various parameters of rejection and vasculopathy. However, we decided to examine the in vitro effects of HLA-G in a smooth muscle cell (SMC) migration assay and whether HLA-G can be modulated pharmacologically. We made the novel observations that purified HLA-G was capable of inhibiting migration of SMCs, a key event in the development of cardiac allograft vasculopathy. IL-10, an anti-inflammatory cytokine, was capable of upregulating HLA-G in a Jeg-3 cell line. The modulation of HLA-G may represent a strategy to protect again vasculopathy, which is a leading cause of morbidity and mortality in heart transplant recipients.MAS