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SorLA,encoded by the gene SORL1,is an intracellular sorting receptor of the VPS10P domain receptor gene family. Although SorLA is best recognized for its ability to shuttle target proteins between intracellular compartments in neurons,recent data suggest that also its microglial expression can be of high relevance for the pathogenesis of brain diseases,including glioblastoma (GBM). Here,we interrogated the impact of SorLA on the functional properties of glioma-associated microglia and macrophages (GAMs). In the GBM microenvironment,GAMs are re-programmed and lose the ability to elicit anti-tumor responses. Instead,they acquire a glioma-supporting phenotype,which is a key mechanism promoting glioma progression. Our re-analysis of published scRNA-seq data from GBM patients revealed that functional phenotypes of GAMs are linked to the level of SORL1 expression,which was further confirmed using in vitro models. Moreover,we demonstrate that SorLA restrains secretion of TNFα from microglia to restrict the inflammatory potential of these cells. Finally,we show that loss of SorLA exacerbates the pro-inflammatory response of microglia in the murine model of glioma and suppresses tumor growth. View Publication

The persistence of HIV-1 in long-lived latent reservoirs during suppressive antiretroviral therapy (ART) remains one of the principal barriers to a functional cure. Blocks to transcriptional elongation play a central role in maintaining the latent state,and several latency reversal strategies focus on the release of positive transcription elongation factor b (P-TEFb) from sequestration by negative regulatory complexes,such as the 7SK complex and BRD4. Another major cellular reservoir of P-TEFb is in Super Elongation Complexes (SECs),which play broad regulatory roles in host gene expression. Still,it is unknown if the release of P-TEFb from SECs is a viable latency reversal strategy. Here,we demonstrate that the SEC is not required for HIV-1 replication in primary CD4+ T cells and that a small molecular inhibitor of the P-TEFb/SEC interaction (termed KL-2) increases viral transcription. KL-2 acts synergistically with other latency reversing agents (LRAs) to reactivate viral transcription in several cell line models of latency in a manner that is,at least in part,dependent on the viral Tat protein. Finally,we demonstrate that KL-2 enhances viral reactivation in peripheral blood mononuclear cells (PBMCs) from people living with HIV (PLWH) on suppressive ART,most notably in combination with inhibitor of apoptosis protein antagonists (IAPi). Taken together,these results suggest that the release of P-TEFb from cellular SECs may be a novel route for HIV-1 latency reactivation. Author summarySince the start of the HIV pandemic,it is estimated that nearly 86 million people have been infected with the virus,and about 40 million people have died. Modern antiretroviral therapies potently restrict viral replication and prevent the onset of AIDS,saving millions of lives. However,these therapies are not curative due to the persistence of the virus in a silenced or ‘latent’ state in long-lived cells of the body. One proposed strategy to clear this latent reservoir,termed “shock and kill”,is to activate these silenced viruses such that the infected cells can be cleared from the body by the immune system. While several drugs have been developed that can activate latent viruses,none have proven effective at reducing the size of the latent reservoir in patients in clinical trials. Here,we describe a new method for latency reactivation using a small molecule inhibitor of a human protein complex called the Super Elongation Complex (SEC). Inhibiting the SEC enhances viral transcription during active infection and triggers the reactivation of latent viruses,especially when in combination with other latency reversing agents. These results pave the way for developing more effective strategies to reactivate latent viruses towards a functional cure. View Publication

Glatiramer acetate (GA or Copaxone) is a drug used to treat experimental autoimmune encephalomyelitis in mice and multiple sclerosis in human. Here,we describe a new mechanism of action for this drug. GA enhanced the cytolysis of human NK cells against autologous and allogeneic immature and mature monocyte-derived dendritic cells (DCs). This drug reduced the percentages of mature DCs expressing CD80,CD83,HLA-DR or HLA-I. In contrast,it did not modulate the percentages of NK cells expressing NKG2D,NKp30,or NKp44. Nonetheless,anti-NKp30 or anti-CD86 inhibited GA-enhanced human NK cell lysis of immature DCs. Hence,CD86,and NKp30 are important for NK cell lysis of immature DCs,whereas CD80,CD83,HLA-DR and HLA-I are important for the lysis of mature DCs when GA is used as a stimulus. Further,GA inhibited the release of IFN-gamma 24 h but increased the release of TNF-alpha 48 h after incubation with NK cells. View Publication

BackgroundAnti-CD19 chimeric antigen receptor T (CAR-T) cell therapy has proven effective for treating relapsed or refractory acute B cell leukemia. However,challenges such as cytokine release syndrome,T cell dysfunction,and exhaustion persist. Enhancing CAR-T cell efficacy through changing CAR internalization and recycling is a promising approach. The transmembrane domain is the easiest motif to optimize for modulating CAR internalization and recycling without introducing additional domains,and its impact on CAR internalization and recycling has not yet been thoroughly explored. In this study,we aim to enhance CAR-T cell function by focusing on the solely transmembrane domain design.MethodsUtilizing plasmid construction and lentivirus generation,we get two different transmembrane CAR-T cells [19CAR-T(1a) and 19CAR-T(8α)]. Through co-culture with tumor cells,we evaluate CAR dynamic change,activation levels,exhaustion markers,mitochondrial function,and differentiation in both CAR-T cells. Furthermore,immunofluorescence microscopy analysis is performed to reveal the localization of internalized CAR molecules. RNA sequencing is used to detect the transcriptome of activated CAR-T cells. Finally,a mouse study is utilized to verify the anti-tumor efficacy of 19CAR-T(1a) cells in vivo.ResultsOur findings demonstrate that 19CAR-T(1a) has lower surface CAR expression,faster internalization,and a higher recycling rate compared to 19CAR-T(8α). Internalized 19CAR(1a) co-localizes more with early and recycling endosomes,and less with lysosomes than 19CAR(8α). These features result in lower activation levels,less cytokine release,and reduced exhaustion markers in 19CAR-T(1a). Furthermore,CAR-T cells with CD1a transmembrane domain also exhibit a superior anti-tumor ability and reduced exhaustion in vivo.ConclusionOverall,we demonstrate that the transmembrane domain plays a critical role in CAR-T cell function. An optimized transmembrane domain can alleviate cytokine release syndrome and reduce CAR-T cell exhaustion,providing a direction for CAR design to enhance CAR-T cell function. View Publication

Leukocyte trafficking to sites of inflammation follows a defined temporal pattern,and evidence suggests that initial neutrophil transendothelial migration modifies endothelial cell phenotype. We tested the hypothesis that preconditioning of human umbilical vein endothelial cells (HUVEC) by neutrophils would also modify the subsequent transendothelial migration of T lymphocytes across cytokine-stimulated HUVEC in an in vitro flow assay. Using fluorescence microscopy,preconditioning of HUVEC by neutrophils was observed to significantly reduce the extent of subsequent stromal cell-derived factor-1alpha (SDF-1alpha [CXCL12])-mediated T lymphocyte transendothelial migration,without reducing accumulation. In contrast,recruitment of a second wave of neutrophils was unaltered. Conditioned medium harvested after transendothelial migration of neutrophils or supernatants from stimulated neutrophils mediated a similar blocking effect,which was negated using a specific neutrophil elastase inhibitor. Furthermore,T lymphocyte transendothelial migration was inhibited by treatment of HUVEC with purified neutrophil elastase,which selectively cleaved the amino terminus of HUVEC-bound SDF-1alpha,which is required for its chemotactic activity. The reduction in T lymphocyte transendothelial migration was not observed using a different chemokine,ELC (CCL19),and was not reversed by replenishment of SDF-1alpha,indicating endothelial retention of the inactivated chemokine. In summary,transmigrating neutrophils secrete localized elastase that is protected from plasma inhibitors,and thereby modulate trafficking of other leukocyte subsets by altering the endothelial-associated chemotactic activities. View Publication

BACKGROUND AND OBJECTIVES: Interactions between acute myelogenous leukemia (AML) blasts and non-leukemic cells in the bone marrow seem to be important for both disease development and susceptibility to chemotherapy. Recent studies have focused on the endothelial cells,but other non-leukemic cells may also be involved. In the present study we investigated how osteoblasts affect native human AML blasts. DESIGN AND METHODS: AML cells were derived from a large group of consecutive patients. The AML blasts and osteoblastic sarcoma cell lines (Cal72,SJSA-1) were incubated together in different chambers separated by a semipermeable membrane. We investigated effects of co-culture on proliferation,apoptosis and cytokine release. RESULTS: The cross-talk between these two cell populations,achieved via release of soluble mediators,resulted in increased AML blast proliferation,including increased proliferation of clonogenic progenitors,but did not affect spontaneous in vitro apoptosis. Both interleukin (IL) 1-b and granulocyte-macrophage colony-stimulating factor were involved in this growth-enhancing cross-talk,and normal osteoblasts could also increase the AML blast proliferation. Furthermore,co-culture of AML blasts with osteoblastic sarcoma cells as well as normal osteoblasts increased the levels of the pro-angiogenic mediator IL8. INTERPRETATION AND CONCLUSIONS: Our in vitro results suggest that the release of soluble mediators by osteoblasts supports leukemic hematopoiesis through two major mechanisms: (i) direct enhancement of AML blast proliferation; and (ii) enhanced angiogenesis caused by increased IL8 levels. View Publication