Effects of everolimus and HLA-G on cellular proliferation and neutrophil adhesion in an in vitro model of cardiac allograft vasculopathy.

Human leukocyte antigen-G (HLA-G) expression is modulated by immunosuppressant use and is associated with lower incidence of graft rejection and cardiac allograft vasculopathy (CAV). We examined whether everolimus induces HLA-G expression and inhibits human coronary artery smooth muscle cell (HCASMC) proliferation, a critical event in CAV. Also, we examined whether TNFα-stimulated neutrophil adhesion is inhibited by HLA-G on human coronary artery endothelial cells (HCAECs). HLA-G expression in HCASMCs following everolimus treatment was determined by western-blot densitometric analysis. HCASMCs proliferation following incubation with recombinant HLA-G was determined by automated cell counter detecting 2-10 µm particles. Assessment of recombinant HLA-G on neutrophil adhesion to HCAECs in response to TNF-α induced-injury was determined by nonstatic adhesion assays. HLA-G expression was upregulated in HCASMCs following everolimus exposure (1000 ng/ml; P < .05). HLA-G (500, 1000 ng/ml; both P < .05) reduced HCASMC proliferation and inhibited TNFα-stimulated neutrophil adhesion to endothelial cells at all concentrations (0.1-1 ng/ml; all P < .001). Our study reveals novel regulation of HLA-G by everolimus, by demonstrating HLA-G upregulation and subsequent inhibition of HCASMC proliferation. HLA-G is a potent inhibitor of neutrophil adhesion to HCAECs. Findings support HLA-G's importance and potential use in heart transplantation for preventative therapy or as a marker to identify patients at high risk for developing CAV.

Markers of inflammation in recipients of continuous-flow left ventricular assist devices.

Although the newer continuous-flow left ventricular assist devices (CF-LVADs) provide clinical advantages over the pulsatile pumps, the effects of low pulsatility on inflammation are incompletely understood. The objective of our study was to examine the levels of inflammatory mediators in CF-LVAD recipients compared with both healthy control subjects and heart failure patients who were candidates for CF-LVAD support. Plasma levels of chemokines, cytokines, and inflammatory markers were measured in 18 CF-LVAD recipients and compared with those of 14 healthy control subjects and 14 heart failure patients who were candidates for CF-LVADs. The levels of granulocyte macrophage-colony stimulating factor, macrophage inflammatory proteins-1ß, and macrophage-derived chemokine were significantly higher in the CF-LVAD group compared with both the heart failure and the healthy control groups, whereas no significant differences were observed between the healthy control subjects and the heart failure groups. Compared with the healthy controls, C-reactive protein, interferon gamma-induced protein-10, monocyte chemotactic protein-1, and interleukin-8 levels were significantly higher in both the CF-LVAD and heart failure groups, but no significant differences were observed between the CF-LVAD recipients and the heart failure patients. Inflammatory markers were elevated in CF-LVAD recipients compared with healthy control subjects and the heart failure patients. Further studies should investigate the clinical implications of elevated levels of inflammation in CF-LVAD recipients.

Can HLA-G polymorphisms predict the development of cardiac allograft vasculopathy?

A 14 bp insertion/deletion polymorphism in exon 8 of the HLA-G gene is associated with mRNA stability and HLA-G expression. In cardiac transplantation, the 14 bp deletion polymorphism plays an important role in the expression of HLA-G and is associated with fewer episodes of cellular rejection. We investigated the association between the 14 bp insertion/deletion HLA-G polymorphism and cardiac allograft vasculopathy (CAV) post heart transplantation. There were no statistically significant differences in the presence of the three HLA-G genotypes (-14 bp/-14 bp, +14 bp/-14 bp, +14 bp/+14 bp) between patients without CAV and patients with CAV at 1 year (p=0.61) or 5 years (p=0.76) post-transplant. We found no correlation between HLA-G genotypes and CAV progression from baseline to 5 years post-transplant (p=0.55). HLA-G polymorphism appears to play an important role as a genetic indicator for cellular rejection post-transplant; however, it is not a reliable marker to identify patients at risk of CAV.