HMG-CoA reductase inhibitors deplete circulating classical and non-classical monocytes following human heart transplantation

BackgroundMonocytes mediate immune responses following solid organ transplantation via cytokine secretion and differentiation to macrophage/dendritic cell lineages. To date, the pleiotropic immunomodulatory effect of statins on human monocytes following human heart transplantation has yet to be elucidated. This study was designed to assess the effects of statin administration on the monocyte repertoire.Methods108 patients were recruited into the study. Clinical data were collected from patients' notes. Peripheral blood immunophenotype was determined via flow cytometry (using CD11c, CD14, CD16, CD49d, CD64, CD80 and CD195).ResultsThere were fewer circulating classical (p = 0.0001) and non-classical (p = 0.0013) monocytes in patients treated with a statin. CD64 expression was down-regulated (p = 0.011 and p = 0.049) whereas CD49d expression was up-regulated (p = 0.004 and p = 0.022) on classical and non-classical monocytes in this group. Patients receiving Atorvastatin had fewer circulating classical monocytes (p = 0.001) compared to patients administered Pravastatin. Patients receiving Pravastatin had fewer circulating non-classical monocytes (p = 0.029) compared to patients administered Atorvastatin.DiscussionStatin administration alters the circulating monocyte repertoire following heart transplantation, including population size, FcγRI and VLA-4 adhesion molecule expression. Furthermore, different statin treatments are associated with a selective depletion of macrophage or DC (re)generating monocytes.