CD14highCD16+ monocytes are the main producers of Interleukin-10 following clinical heart transplantation.

Introduction: Following heart transplantation, a cascade of immunological responses is initiated influencing the clinical outcome and long-term survival of the transplanted patients. The anti-inflammatory cytokine interleukin-10 (IL-10) was shown to be elevated in the blood of heart transplant recipients directly after transplantation but the releasing cell populations and the composition of lymphocyte subsets following transplantation have not been thoroughly studied. Methods: We identified immune cells by immunophenotyping and analyzed intracellular IL-10 production in peripheral blood mononuclear cells (PBMC) of heart transplanted patients (n= 17) before, directly after and 24h post heart transplantation. The cells were stimulated with lipopolysaccharide or PMA/Ionomycin to enhance cytokine production within leukocytes in vitro. Results and discussion: We demonstrate that intermediate monocytes (CD14highCD16+), but not CD8+ T cells, CD4+ T cells, CD56+ NK cells or CD20+ B cells appeared to be the major IL-10 producers within patients PBMC following heart transplantation. Consequently, the absolute monocyte count and the ratio of intermediate monocytes to classical monocytes (CD14+CD16-) were specifically increased in comparison to pre transplant levels. Hence, this population of monocytes, which has not been in the focus of heart transplantation so far, may be an important modulator of clinical outcome and long-term survival of heart transplant recipients. Alteration of blood-circulating monocytes towards a CD14highCD16+ phenotype could therefore shift the pro-inflammatory immune response towards induction of graft tolerance, and may pave the way for the optimization of immunosuppression.

Identification of distinct secretory patterns and their regulatory networks of ischemia versus reperfusion phases in clinical heart transplantation.

BACKGROUND: Ischemia/reperfusion injury (IRI) is associated with inflammatory responses contributing to the development of primary graft dysfunction (PGD) and rejection. Here, we investigated the pathophysiology of IRI and the early phase after heart transplantation (HTx) regarding its cytokine/chemokine and endothelial networks. METHODS: Using multiplex technology, we assessed protein concentrations in plasma samples of HTx recipients (n = 11) pre-, postoperatively, 24 h and 3 weeks after HTx. The same proteins were quantified in organ storage solutions at the end of heart storage (n = 10). Unsupervised cluster, principal component analysis (PCA), K-nearest neighbor (KNN) network classifier analysis, ANOVA and Spearman correlation analyses were performed to identify specific patterns for IRI and individual kinetics of important soluble factors in HTx. RESULTS: Unique patterns of soluble factors were identified in plasma of HTx patients. KNN analysis defined IL-10, IL-6, sIL-6Rα, IL-1RA, IL-16, sVEGFR-1, IGFBP-1, HGF and sHer-2 as strongest signals directly post-Tx declining 24 hrs after HTx. By contrast, MIF, osteopontin (OPN), sVCAM-1 and sICAM-1, IGFBP-1, SCGF-ß, HGF were highly enriched in organ storage solutions, reflecting distinct ischemic (storage solution) vs. reperfusion (plasma) signatures. CONCLUSIONS: We identified specific inflammatory signatures for ischemic vs. reperfusion phases of HTx, associated with pro- as well as anti-inflammatory and endothelial biomarker candidates for IRI. These signatures might help to identify potential danger factors and their networks at both the ex situ (ischemic) as well as the reperfusion phase in the recipient after implantation.