技术资料

The hexamethylene bisacetamide (HMBA) anticancer drug was dismissed due to limited efficacy in leukemic patients but it may re-enter into the clinics in HIV-1 eradication strategies because of its recently disclosed capacity to reactivate latent virus. Here,we investigated the impact of HMBA on the cytotoxicity of natural killer (NK) cells against acute T lymphoblastic leukemia (T-ALL) cells or HIV-1-infected T cells that exit from latency. We show that in T-ALL cells HMBA upmodulated MICB and ULBP2 ligands for the NKG2D activating receptor. In a primary CD4+ T cell-based latency model,HMBA did not reactivate HIV-1,yet enhanced ULBP2 expression on cells harboring virus reactivated by prostratin (PRO). However,HMBA reduced the expression of NKG2D and its DAP10 adaptor in NK cells,hence impairing NKG2D-mediated cytotoxicity and DAP10-dependent response to IL-15 stimulation. Alongside,HMBA dampened killing of T-ALL targets by IL-15-activated NK cells and impaired NK cell-mediated clearance of PRO-reactivated HIV-1+ cells. Overall,our results demonstrate a dominant detrimental effect of HMBA on the NKG2D pathway that crucially controls NK cell-mediated killing of tumors and virus-infected cells,providing one possible explanation for poor clinical outcome in HMBA-treated cancer patients and raising concerns for future therapeutic application of this drug. View Publication

Lymphocyte activation gene-3 (LAG-3) is an inhibitory receptor expressed by CD4+ T cells and tempers their homeostatic expansion. Because CD4+ T cell proliferation is tightly coupled to bioenergetics,we investigate the role of LAG-3 in modulating naive CD4+ T cell metabolism. LAG-3 deficiency enhances the metabolic profile of naive CD4+ T cells by elevating levels of mitochondrial biogenesis. In vivo,LAG-3 blockade partially restores expansion and the metabolic phenotype of wild-type CD4+ T cells to levels of Lag3-/- CD4+ T cells,solidifying that LAG-3 controls these processes. Lag3-/- CD4+ T cells also demonstrate greater signal transducer and activator of transcription 5 (STAT5) activation,enabling resistance to interleukin-7 (IL-7) deprivation. These results implicate this pathway as a target of LAG-3-mediated inhibition. Additionally,enhancement of STAT5 activation,as a result of LAG-3 deficiency,contributes to greater activation potential in these cells. These results identify an additional mode of regulation elicited by LAG-3 in controlling CD4+ T cell responses. View Publication

CD46 is a glycoprotein with important functions in innate and adaptive immune responses. Functionally different isoforms are generated by alternative splicing at exons 7-9 (BC and C isoforms) and exon 13 (CYT-1 and CYT-2 isoforms) giving rise to BC1,BC2,C1 and C2. We developed a novel real-time PCR assay that allows quantitative comparisons between these isoforms. Their relative frequency in CD4(+) T cells from 100 donors revealed a distribution with high interpersonally variability. Importantly,the distribution between the isoforms was not random and although splicing favoured inclusion of exon 8 (BC isoforms),exclusion of exon 8 (C isoforms) was significantly linked to exclusion of exon 13 (CYT-2 isoforms). Despite inter-individual differences,CD4(+) and CD8(+) T cells,B cells,NK cells and monocytes expressed similar isoform profiles intra-individually. However,memory/effector CD4(+) T cells had a significantly higher frequency of CYT-2 when compared with naïve CD4(+) T cells. Likewise,in vitro activation of naïve and total CD4(+) T cells increased the expression of CYT-2. This indicates that although splicing factors determine a certain expression profile in an individual,the profile can be modulated by external stimuli. This suggests a mechanism by which alterations in CD46 isoforms may temporarily regulate the immune response. View Publication