Objective-Pleiotrophin (PTN) is a cytokine that is expressed by monocytes/macrophages in ischemic tissues and that promotes neovascularization, presumably by stimulating proliferation of local endothelial cells. However, the effect of PTN on monocytes/macrophages remains unknown. We investigated the role of PTN in regulating the phenotype of monocytes/macrophages. Methods and Results-RT-PCR, real-time PCR, and fluorescence-activated cell sorter analysis revealed that the expression of PTN by monocytic cells led to a downregulation of CD68, c-fms, and CD14 monocytic cell markers and an upregulation of FLK-1, Tie-2, vascular endothelial-cadherin, platelet endothelial cell adhesion molecule-1, endothelial NO synthase, von Willebrand factor, CD34, GATA-2, and GATA-3 endothelial cell markers. Fibrin gel assays showed that the treatment of mouse and human monocytic cells with PTN led to the formation of tube-like structures. In vivo studies showed that PTN-expressing monocytic cells incorporated into the blood vessels of the quail chorioallantoic membrane. The intracardial injection of PTN-expressing monocytic cells into chicken embryos showed that cells integrated only into the developing vasculature. Finally, the injection of PTN-expressing monocytes into a murine ischemic hindlimb model significantly improved perfusion of the ischemic tissue.

SummaryBackground: Platelet-monocyte aggregates (PMA) and C-reactive protein (CRP) are increased in unstable coronary disease. The interrelation of PMA with platelet activation, systemic inflammation, and their association with markers of myocardial injury has not been studied extensively.Hypothesis: The study was undertaken to evaluate the association of CRP, PMA, and cardiac troponin I (cTnI) in patients admitted with non-ST elevation acute coronary syndromes (NSTE-ACS).Methods: In all, 69 consecutive patients with NSTE-ACS, 58 patients with stable angina pectoris (SAP), and 46 control patients without coronary artery disease were selected; PMA, sP-selectin, sCD40L inter leukin, (IL)-6, CRP, and cTnI concentrations were measured in these patients at the time of admission. Patients with NSTE-ACS were classified into two groups: those with troponin normal (cTnI < 0.06 ng/ml) and those with troponin elevation (cTnI ≥ 0.06 ng/ml). Their risk for clinical inhospital cardiac events (death and nonfatal myocardial infarction) was analyzed.

We demonstrated that the presence of GATA3-positive macrophages adversely affects remodeling of the myocardium in response to ischemia or pressure overload, whereas the absence of these macrophages led to a significant improvement in cardiac function. Targeting of signaling pathways that lead to the expression of GATA3 in macrophages may have favorable cardiac outcomes.

Forkhead box P3 (Foxp3) is well known for its highly restricted expression in T regulatory cells (Tregs). A recent study suggested the existence of a Foxp3 positive macrophage subpopulation in mouse bone marrow, spleen, liver, lymph nodes, and thymus that exhibited immune regulatory effect similar to Tregs. Before this report was retracted, we attempted to study the function of this macrophage subpopulation in a mouse model of hyperlipidemia. Bone marrow and spleen cells isolated from C57BL/6 apo E−/− mice were stained with anti-CD11b, anti-F4/80 and anti-Foxp3 and analyzed by flow cytometry. Our results showed that 3.06–8.08% of CD11b+F4/80+ macrophages from bone marrow cells and 0.24–2.21% from splenic were Foxp3-positive. Unexpectedly, unstained or isotype stained controls also showed strong autofluorescence and similar percentages of these cells fell within the same FL1 channel that counted the anti-Foxp3 stained population. Back gating of the autofluorescent population onto a SSC/FSC plot showed that this population of cells had a higher side scatter. The peritoneal macrophages (PMø) exhibited similar autofluorescence. We used qPCR to further evaluate the expression of Foxp3 mRNA in PMø that were treated with M-CSF, M-CSF+IL-4, M-CSF+TGFβ1 or in BMDM treated with TGFβ1 in the presence of anti-CD3 and CD28 antibody co-stimulators. No expression of Foxp3 mRNA was detected in either cell culture systems, whereas robust Foxp3 gene expression was induced in naïve CD4+ cells stimulated with TGFβ1. Consistent with these findings, fluorescence microscopy showed no Foxp3 protein expression in PMø, however Foxp3 expression was easily detected in induced Tregs. We conclude that the reported expression of Foxp3 in macrophages is likely an artifact and that a stringent multimodality approach is critical to demonstrate candidate gene expression in any cell type.