A major atheroprotective functionality of high-density lipoproteins (HDLs) is to promote ''reverse cholesterol transport'' (RCT). In this process, HDLs mediate the efflux and transport of cholesterol from peripheral cells and its subsequent transport to the liver for further metabolism and biliary excretion. We have previously demonstrated in cultured hepatocytes that P2Y 13 (purinergic receptor P2Y, G protein-coupled, 13) activation is essential for HDL uptake but the potential of P2Y 13 as a target to promote RCT has not been documented. Here, we show that P2Y 13 -deficient mice exhibited a decrease in hepatic HDL cholesterol uptake, hepatic cholesterol content, and biliary cholesterol output, although their plasma HDL and other lipid levels were normal. These changes translated into a substantial decrease in the rate of macrophage-to-feces RCT. Therefore, hallmark features of RCT are impaired in P2Y 13 -deficient mice. Furthermore, cangrelor, a partial agonist of P2Y 13 , stimulated hepatic HDL uptake and biliary lipid secretions in normal mice and in mice with a targeted deletion of scavenger receptor class B type I (SR-BI) in liver (hypomSR-BIknockout liver ) but had no effect in P2Y 13 knockout mice, which indicate that P2Y 13 -mediated HDL uptake pathway is independent of SR-BI-mediated HDL selective cholesteryl ester uptake. Conclusion: These results establish P2Y 13 as an attractive novel target for modulating RCT and support the emerging view that steady-state plasma HDL levels do not necessarily reflect the capacity of HDL to promote RCT.

The effects of ADP on the biology of dendritic cells have been studied much less than those of ATP or adenosine. In this study, we showed that adenosine-5′-O-(2-thiodiphosphate) (ADPβS) induced intracellular Ca2+ transients in murine dendritic cells (DCs). This effect was abolished by AR-C69931MX, a dual P2Y12 and P2Y13 receptor antagonist. RT-PCR experiments revealed the expression of both P2Y12 and P2Y13 mRNA in DCs. The Ca2+ response to ADPβS was maintained in P2Y13-deficient DCs, whereas it was abolished completely in P2Y12−/− DCs. ADPβS stimulated FITC-dextran and OVA capture in murine DCs through macropinocytosis, and this effect was abolished in P2Y12−/− DCs. ADPβS had a similar effect on FITC-dextran uptake by human monocyte-derived DCs. OVA loading in the presence of ADPβS increased the capacity of DCs to stimulate OVA-specific T cells, whereas ADPβS had no effect on the ability of DCs to stimulate allogeneic T cells. Moreover, after immunization against OVA, the serum level of anti-OVA IgG1 was significantly lower in P2Y12−/− mice than that in wild-type controls. In conclusion, we have shown that the P2Y12 receptor is expressed in murine DCs and that its activation increased Ag endocytosis by DCs with subsequent enhancement of specific T cell activation.

BelgiumAdenosine triphosphate has previously been shown to induce semi-mature human monocyte-derived dendritic cells (DC). These are characterized by the up-regulation of co-stimulatory molecules, the inhibition of IL-12 and the up-regulation of some genes involved in immune tolerance, such as thrombospondin-1 and indoleamine 2,3-dioxygenase. The actions of adenosine triphosphate are mediated by the P2Y 11 receptor; since there is no functional P2Y 11 gene in the murine genome, we investigated the action of adenine nucleotides on murine DC. Adenosine 5 0 -(3-thiotriphosphate) and adenosine inhibited the production of IL-12p70 by bone marrow-derived DC (BMDC). These inhibitions were relieved by 8-p-sulfophenyltheophylline, an adenosine receptor antagonist. The use of selective ligands and A 2B -/-BMDC indicated the involvement of the A 2B receptor. A microarray experiment, confirmed by quantitative PCR, showed that, in presence of LPS, 5 0 -(N-ethylcarboxamido) adenosine (NECA, the most potent A 2B receptor agonist) regulated the expression of several genes: arginase I and II, thrombospondin-1 and vascular endothelial growth factor were up-regulated whereas CCL2 and CCL12 were downregulated. We further showed that NECA, in combination with LPS, increased the arginase I enzymatic activity. In conclusion, the described actions of adenine nucleotides on BMDC are mediated by their degradation product, adenosine, acting on the A 2B receptor, and will possibly lead to an impairment of Th1 response or tolerance.

The triple-negative breast cancer (TNBC) subtype occurs in about 15% of breast cancer and is an aggressive subtype of breast cancer with poor outcome. Furthermore, treatment of patients with TNBC is more challenging due to the heterogeneity of the disease and the absence of well-defined molecular targets. Microribonucleic acid (RNA) represents a new class of biomarkers that are frequently dysregulated in cancer. It has been described that the microRNA miR-210 is highly expressed in TNBC, and its overexpression had been linked to poor prognosis. TNBC are often infiltrated by immune cells that play a key role in cancer progression. The techniques traditionally used to analyze miR-210 expression such as next generation sequencing or quantitative real-time polymerase chain reaction (PCR) do not allow the precise identification of the cellular subtype expressing the microRNA. In this study, we have analyzed miR-210 expression by in situ hybridization in TNBC. The miR-210 signal was detected in tumor cells, but also in the tumor microenvironment, in a region positive for the pan-leucocyte marker CD45-LCA. Taken together, our results demonstrate that miR-210 is expressed in tumor cells but also in the tumor microenvironment. Our results also highlight the utility of using complementary approaches to take into account the cellular context of microRNA expression.