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The intracellular expression of the programmed death receptor 1 (PD1) identifies a subset of naive T(reg) cells with enhanced suppressive ability; antigen stimulation results in the surface expression of PD1. Because the role of T(reg) impairments in multiple sclerosis (MS) is still contradictory,we analyzed naive PD1- and PD1+ T(reg) cells in peripheral blood and cerebrospinal fluid (CSF) of relapsing-remitting multiple sclerosis (RR-MS) patients and of healthy control subjects. Results showed that 1) CSF PD1- T(reg) cells were significantly augmented in MS patients; 2) PD1- T(reg) cells were significantly increased in the peripheral blood of patients with stable disease (SMS) compared to those with acute (AMS) disease,and in patients responding to glatiramer acetate (COPA) compared to AMS- and COPA-unresponsive patients; and 3) PD1+ T(reg) cells were similar in CSF and peripheral blood of all groups analyzed. PD1- T(reg) cells were not increased in the peripheral blood of interferon-beta (IFNbeta) -responsive patients,but the suppressive ability of T(reg) cells was significantly higher in SMS and in COPA- or IFNbeta-responsive compared to AMS- and COPA-unresponsive individuals. The data herein suggest that PD1- T(reg) cells play a pivotal role in MS and offer a biological explanation for disease relapse and for the mechanism associated with response to COPA and IFNbeta. View Publication

Bacillus anthracis secretes two bipartite toxins,edema toxin (ET) and lethal toxin (LT),which impair immune responses and contribute directly to the pathology associated with the disease anthrax. Edema factor,the catalytic subunit of ET,is an adenylate cyclase that impairs host defenses by raising cellular cyclic AMP (cAMP) levels. Synthetic cAMP analogues and compounds that raise intracellular cAMP levels lead to phenotypic and functional changes in dendritic cells (DCs). Here,we demonstrate that ET induces a maturation state in human monocyte-derived DCs (MDDCs) similar to that induced by lipopolysaccharide (LPS). ET treatment results in downregulation of DC-SIGN,a marker of immature DCs,and upregulation of DC maturation markers CD83 and CD86. Maturation of DCs by ET is accompanied by an increased ability to migrate toward the lymph node-homing chemokine macrophage inflammatory protein 3beta,like LPS-matured DCs. Interestingly,cotreating with LT differentially affects the ET-induced maturation of MDDCs while not inhibiting ET-induced migration. These findings reveal a mechanism by which ET impairs normal innate immune function and may explain the reported adjuvant effect of ET. View Publication

Bone marrow-derived mesenchymal stromal cells (MSC) possess an immune plasticity manifested by either an immunosuppressive or,when activated with IFN-gamma,an APC phenotype. Herein,TLR expression by MSC and their immune regulatory role were investigated. We observed that human MSC and macrophages expressed TLR3 and TLR4 at comparable levels and TLR-mediated activation of MSC resulted in the production of inflammatory mediators such as IL-1beta,IL-6,IL-8/CXCL8,and CCL5. IFN-alpha or IFN-gamma priming up-regulated production of these inflammatory mediators and expression of IFNB,inducible NO synthase (iNOS),and TRAIL upon TLR activation in MSC and macrophages,but failed to induce IL-12 and TNF-alpha production in MSC. Nonetheless,TLR activation in MSC resulted in the formation of an inflammatory site attracting innate immune cells,as evaluated by human neutrophil chemotaxis assays and by the analysis of immune effectors retrieved from Matrigel-embedded MSC injected into mice after in vitro preactivation with cytokines and/or TLR ligands. Hence,TLR-activated MSC are capable of recruiting immune inflammatory cells. In addition,IFN priming combined with TLR activation may increase immune responses induced by Ag-presenting MSC through presentation of Ag in an inflammatory context,a mechanism that could be applied in a cell-based vaccine. View Publication

Amyotrophic lateral sclerosis (ALS) is an incurable neuromuscular disease that leads to a profound loss of life quality and premature death. Around 10% of the cases are inherited and ALS8 is an autosomal dominant form of familial ALS caused by mutations in the vamp-associated protein B/C (VAPB) gene. The VAPB protein is involved in many cellular processes and it likely contributes to the pathogenesis of other forms of ALS besides ALS8. A number of successful drug tests in ALS animal models could not be translated to humans underscoring the need for novel approaches. The induced pluripotent stem cells (iPSC) technology brings new hope,since it can be used to model and investigate diseases in vitro. Here we present an additional tool to study ALS based on ALS8-iPSC. Fibroblasts from ALS8 patients and their non-carrier siblings were successfully reprogrammed to a pluripotent state and differentiated into motor neurons. We show for the first time that VAPB protein levels are reduced in ALS8-derived motor neurons but,in contrast to over-expression systems,cytoplasmic aggregates could not be identified. Our results suggest that optimal levels of VAPB may play a central role in the pathogenesis of ALS8,in agreement with the observed reduction of VAPB in sporadic ALS. View Publication

Many breast cancer deaths result from tumors acquiring resistance to available therapies. Thus,new therapeutic agents are needed for targeting drug-resistant breast cancers. Drug-refractory breast cancers include HER2+ tumors that have acquired resistance to HER2-targeted antibodies and kinase inhibitors,and Triple-Negative" Breast Cancers (TNBCs) that lack the therapeutic targets Estrogen Receptor� View Publication

Oxidative stress,caused by the imbalance between reactive species generation and the dysfunctional capacity of antioxidant defenses,is one of the characteristic features of cancer. Here,we quantified hydrogen peroxide in the tumor microenvironment (TME) and demonstrated that hydrogen peroxide concentrations are elevated in tumor interstitial fluid isolated from murine breast cancers in vivo,when compared with blood or normal subcutaneous fluid. Therefore,we investigated the effects of increased hydrogen peroxide concentration on immune cell functions. NK cells were more susceptible to hydrogen peroxide than T cells or B cells,and by comparing T,B,and NK cells' sensitivities to redox stress and their antioxidant capacities,we identified peroxiredoxin-1 (PRDX1) as a lacking element of NK cells' antioxidative defense. We observed that priming with IL15 protected NK cells' functions in the presence of high hydrogen peroxide and simultaneously upregulated PRDX1 expression. However,the effect of IL15 on PRDX1 expression was transient and strictly dependent on the presence of the cytokine. Therefore,we genetically modified NK cells to stably overexpress PRDX1,which led to increased survival and NK cell activity in redox stress conditions. Finally,we generated PD-L1-CAR NK cells overexpressing PRDX1 that displayed potent antitumor activity against breast cancer cells under oxidative stress. These results demonstrate that hydrogen peroxide,at concentrations detected in the TME,suppresses NK cell function and that genetic modification strategies can improve CAR NK cells' resistance and potency against solid tumors. View Publication

G-protein coupled receptor kinases (GRKs) participate in the regulation of chemokine receptors by mediating receptor desensitization. They can be recruited to agonist-activated G-protein coupled receptors (GPCRs) and phosphorylate their intracellular parts,which eventually blocks signal propagation and often induces receptor internalization. However,there is growing evidence that GRKs can also control cellular functions beyond GPCR regulation. Immune cells commonly express two to four members of the GRK family (GRK2,GRK3,GRK5,GRK6) simultaneously,but we have very limited knowledge about their interplay in primary immune cells. In particular,we are missing comprehensive studies comparing the role of this GRK interplay for (a) multiple GPCRs within one leukocyte type,and (b) one specific GPCR between several immune cell subsets. To address this issue,we generated mouse models of single,combinatorial and complete GRK knockouts in four primary immune cell types (neutrophils,T cells,B cells and dendritic cells) and systematically addressed the functional consequences on GPCR-controlled cell migration and tissue localization. Our study shows that combinatorial depletions of GRKs have pleiotropic and cell-type specific effects in leukocytes,many of which could not be predicted. Neutrophils lacking all four GRK family members show increased chemotactic migration responses to a wide range of GPCR ligands,whereas combinatorial GRK depletions in other immune cell types lead to pro- and anti-migratory responses. Combined depletion of GRK2 and GRK6 in T cells and B cells shows distinct functional outcomes for (a) one GPCR type in different cell types,and (b) different GPCRs in one cell type. These GPCR-type and cell-type specific effects reflect in altered lymphocyte chemotaxis in vitro and localization in vivo. Lastly,we provide evidence that complete GRK deficiency impairs dendritic cell homeostasis,which unexpectedly results from defective dendritic cell differentiation and maturation in vitro and in vivo. Together,our findings demonstrate the complexity of GRK functions in immune cells,which go beyond GPCR desensitization in specific leukocyte types. Furthermore,they highlight the need for studying GRK functions in primary immune cells to address their specific roles in each leukocyte subset. View Publication

Glioblastoma (GBM) is a malignant brain tumor with diffuse infiltration. Here,we demonstrate how GBM cells usurp guidance receptor Plexin-B2 for confined migration through restricted space. Using live-cell imaging to track GBM cells negotiating microchannels,we reveal endocytic vesicle accumulation at cell front and filamentous actin assembly at cell rear in a polarized manner. These processes are interconnected and require Plexin-B2 signaling. We further show that Plexin-B2 governs membrane tension and other membrane features such as endocytosis,phospholipid composition,and inner leaflet surface charge,thus providing biophysical mechanisms by which Plexin-B2 promotes GBM invasion. Together,our studies unveil how GBM cells regulate membrane tension and mechano-electrical coupling to adapt to physical constraints and achieve polarized confined migration. The biomechanical mechanisms enabling the invasive growth of brain tumors remain opaque. Here,Junqueira Alves et al. reveal that the guidance receptor Plexin-B2 controls membrane tension,facilitating confined migration of brain tumor cells. View Publication

Mycobacterium tuberculosis ( Mtb ),the causative agent of tuberculosis (TB),is the most common coinfection among people living with HIV-1. This coinfection is associated with accelerated HIV-1 disease progression and reduced survival. However,the impact of the HIV-1/TB coinfection on HIV-1 replication and latency in CD4 + T cells remains poorly studied. Using the acellular fraction of tuberculous pleural effusion (TB-PE),we investigated whether viral replication and HIV-1 latency in CD4 + T cells are affected by a TB-associated microenvironment. Our results revealed that TB-PE impaired T cell receptor-dependent cell activation and decreased HIV-1 replication in CD4 + T cells. Moreover,this immunosuppressive TB microenvironment promoted viral latency and inhibited HIV-1 reactivation. This study indicates that the TB-induced immune response may contribute to the persistence of the viral reservoir by silencing HIV-1 expression,allowing the virus to persist undetected by the immune system,and increasing the size of the latent HIV-1 reservoir. Subject areas: Immunology,Virology View Publication

Both antitumor and protumor property of mesenchymal stem cells (MSCs) have been demonstrated. We hypothesize that this contradiction is due to the heterogeneity of MSC subsets and that extracellular vesicles (EVs) from distinct MSC subsets can transfer the corresponding antitumor activities. Here we evaluated the antitumor activities of two subsets of adipose-derived mesenchymal stem cells (ADSCs) and ADSC-derived EVs (ADSC-EVs) in immunocompetent syngeneic mouse models of breast cancer. We identified CD90high and CD90low ADSC subsets and demonstrated that CD90high ADSCs could be converted into CD90low ADSCs by stimulation with LPS. CD90low ADSCs and its derived EVs significantly inhibited tumor growth in tumor-bearing mice. Benefit of tumor control were associated with decreased tumor cell proliferation and migration,and enhanced tumor cell apoptosis mediated by ADSC-EVs. Antioncogenic miRNA-16-5p loaded CD90low ADSC-EVs further significantly enhanced antitumor activities. Taken together,this study represents the first attempt to apply our newly identified antitumor ADSCs and its derived EVs in preclinical treatment of breast cancer. This study also provides the evidence that EVs can serve as a novel and effective therapeutics or drug delivery vesicle. This new therapeutic approach could be potentially applicable to breast cancer and many other types of cancer. View Publication

Induced pluripotent stem cells (iPSCs) are commonly used to model human genetic diseases. Two main strategies are used. The first involves making iPSC lines from individual cases with a disease,and the second involves making disease-relevant gene edits in established iPSC lines. Because generating gene-edited lines is time consuming and expensive,most studies begin with one starting iPSC stock line and evaluate several gene-edited sublines. The current studies focus on gene-editing to model Lesch–Nyhan disease (LND),which is caused by mutations in the HPRT1 gene. The same pathogenic c.508C>T edit was made in four well-established stock lines,and three gene-edited lines were isolated from each. RNA sequencing (RNAseq) was,then,used to evaluate the impact of the gene edit. Gene-edited lines were compared to their corresponding stock lines,as well as to each other. An aggregate analysis of all lines combined was also conducted to determine the most robust findings across all lines. Results from gene editing were further compared with iPSC lines derived from individual cases with LND,to determine how closely findings from gene editing match results obtained with case-derived lines. There were two main findings. First,the same gene edit has a different impact on gene expression when starting with different starting stock lines. Second,the gene editing strategy does not produce the same results as the case-derived strategy. Potential explanations for these differences are addressed,along with the relevance of these two different strategies for disease modeling. View Publication

Chronic myeloid leukemia (CML) is genetically characterized by the Philadelphia (Ph) chromosome,formed through a reciprocal translocation between chromosomes 9 and 22 and giving rise to the constitutively active tyrosine kinase P210 BCR/ABL1. Therapeutic strategies aiming for a cure of CML will require full eradication of Ph chromosome-positive (Ph(+)) CML stem cells. Here we used gene-expression profiling to identify IL-1 receptor accessory protein (IL1RAP) as up-regulated in CML CD34(+) cells and also in cord blood CD34(+) cells as a consequence of retroviral BCR/ABL1 expression. To test whether IL1RAP expression distinguishes normal (Ph(-)) and leukemic (Ph(+)) cells within the CML CD34(+)CD38(-) cell compartment,we established a unique protocol for conducting FISH on small numbers of sorted cells. By using this method,we sorted cells directly into drops on slides to investigate their Ph-chromosome status. Interestingly,we found that the CML CD34(+)CD38(-)IL1RAP(+) cells were Ph(+),whereas CML CD34(+)CD38(-)IL1RAP(-) cells were almost exclusively Ph(-). By performing long-term culture-initiating cell assays on the two cell populations,we found that Ph(+) and Ph(-) candidate CML stem cells could be prospectively separated. In addition,by generating an anti-IL1RAP antibody,we provide proof of concept that IL1RAP can be used as a target on CML CD34(+)CD38(-) cells to induce antibody-dependent cell-mediated cytotoxicity. This study thus identifies IL1RAP as a unique cell surface biomarker distinguishing Ph(+) from Ph(-) candidate CML stem cells and opens up a previously unexplored avenue for therapy of CML. View Publication