技术资料

We investigated the contribution of host immune cells to bacterial killing in a whole-blood bactericidal activity (WBA) assay,an ex vivo model used to test efficacy of drugs against mycobacterium tuberculosis (Mtb). We performed WBA assays with immuno-magnetic depletion of specific cell types,in the presence or absence of rifampicin. Innate immune cells decreased Mtb growth in absence of drug,but appeared to diminish the cidal activity of rifampicin,possibly attributable to intracellular bacterial sequestration. Adaptive immune cells had no effect with or without drug. The WBA assay may have potential for testing adjunctive host-directed therapies acting on phagocytic cells. View Publication

Multiple myeloma (MM) is a tumor of plasma cells (PCs). Due to the intense immunoglobulin secretion,PCs are prone to endoplasmic reticulum stress and activate several stress-managing pathways,including autophagy. Indeed,autophagy deregulation is maladaptive for MM cells,resulting in cell death. CK1alpha,a pro-survival kinase in MM,has recently been involved as a regulator of the autophagic flux and of the transcriptional competence of the autophagy-related transcription factor FOXO3a in several cancers. In this study,we investigated the role of CK1alpha in autophagy in MM. To study the autophagic flux we generated clones of MM cell lines expressing the mCherry-eGFP-LC3B fusion protein. We observed that CK1 inhibition with the chemical ATP-competitive CK1 alpha/delta inhibitor D4476 resulted in an impaired autophagic flux,likely due to an alteration of lysosomes acidification. However,D4476 caused the accumulation of the transcription factor FOXO3a in the nucleus,and this was paralleled by the upregulation of mRNA coding for autophagic genes. Surprisingly,silencing of CK1alpha by RNA interference triggered the autophagic flux. However,FOXO3a did not shuttle into the nucleus and the transcription of autophagy-related FOXO3a-dependent genes was not observed. Thus,while the chemical inhibition with the dual CK1alpha/delta inhibitor D4476 induced cell death as a consequence of an accumulation of ineffective autophagic vesicles,on the opposite,CK1alpha silencing,although it also determined apoptosis,triggered a full activation of the early autophagic flux,which was then not supported by the upregulation of autophagic genes. Taken together,our results indicate that the family of CK1 kinases may profoundly influence MM cells survival also through the modulation of the autophagic pathway. View Publication

Pathobiology of several chronic inflammatory disorders,including ulcerative colitis and Crohn's disease is related to intermittent,spontaneous injury/ulceration of mucosal surfaces. Disease morbidity has been associated with pathologic release of the pro-inflammatory cytokine tumor necrosis factor alpha (TNFalpha). In this report,we show that TNFalpha promotes intestinal mucosal repair through upregulation of the GPCR platelet activating factor receptor (PAFR) in the intestinal epithelium. Platelet activating factor (PAF) was increased in healing mucosal wounds and its engagement with epithelial PAFR leads to activation of epidermal growth factor receptor,Src and Rac1 signaling to promote wound closure. Consistent with these findings,delayed colonic mucosal repair was observed after administration of a neutralizing TNFalpha antibody and in mice lacking PAFR. These findings suggest that in the injured mucosa,the pro-inflammatory milieu containing TNFalpha and PAF sets the stage for reparative events mediated by PAFR signaling. View Publication

Identifying targets present in the tumor microenvironment that contribute to immune evasion has become an important area of research. In this study,we identified EphB4-ephrin-B2 signaling as a regulator of both innate and adaptive components of the immune system. EphB4 belongs to receptor tyrosine kinase family that interacts with ephrin-B2 ligand at sites of cell-cell contact,resulting in bidirectional signaling. We found that EphB4-ephrin-B2 inhibition alone or in combination with radiation (RT) reduced intratumoral regulatory T cells (Tregs) and increased activation of both CD8+ and CD4+Foxp3- T cells compared with the control group in an orthotopic head and neck squamous cell carcinoma (HNSCC) model. We also compared the effect of EphB4-ephrin-B2 inhibition combined with RT with combined anti-PDL1 and RT and observed similar tumor growth suppression,particularly at early time-points. A patient-derived xenograft model showed reduction of tumor-associated M2 macrophages and favored polarization towards an antitumoral M1 phenotype following EphB4-ephrin-B2 inhibition with RT. In vitro,EphB4 signaling inhibition decreased Ki67-expressing Tregs and Treg activation compared with the control group. Overall,our study is the first to implicate the role of EphB4-ephrin-B2 in tumor immune response. Moreover,our findings suggest that EphB4-ephrin-B2 inhibition combined with RT represents a potential alternative for patients with HNSCC and could be particularly beneficial for patients who are ineligible to receive or cannot tolerate anti-PDL1 therapy. SIGNIFICANCE: These findings present EphB4-ephrin-B2 inhibition as an alternative to anti-PDL1 therapeutics that can be used in combination with radiation to induce an effective antitumor immune response in patients with HNSCC. View Publication

Sterol regulatory element binding proteins (SREBPs) are a family of transcription factors that regulate lipid biosynthesis and adipogenesis by controlling the expression of several enzymes required for cholesterol,fatty acid,triacylglycerol and phospholipid synthesis. In vertebrates,SREBP activation is mainly controlled by a complex and well-characterized feedback mechanism mediated by cholesterol,a crucial bio-product of the SREBP-activated mevalonate pathway. In this work,we identified acto-myosin contractility and mechanical forces imposed by the extracellular matrix (ECM) as SREBP1 regulators. SREBP1 control by mechanical cues depends on geranylgeranyl pyrophosphate,another key bio-product of the mevalonate pathway,and impacts on stem cell fate in mouse and on fat storage in Drosophila. Mechanistically,we show that activation of AMP-activated protein kinase (AMPK) by ECM stiffening and geranylgeranylated RhoA-dependent acto-myosin contraction inhibits SREBP1 activation. Our results unveil an unpredicted and evolutionary conserved role of SREBP1 in rewiring cell metabolism in response to mechanical cues. View Publication

The Plasmodium falciparum reticulocyte-binding protein homolog 5 (PfRH5) is the leading target for next-generation vaccines against the disease-causing blood-stage of malaria. However,little is known about how human antibodies confer functional immunity against this antigen. We isolated a panel of human monoclonal antibodies (mAbs) against PfRH5 from peripheral blood B cells from vaccinees in the first clinical trial of a PfRH5-based vaccine. We identified a subset of mAbs with neutralizing activity that bind to three distinct sites and another subset of mAbs that are non-functional,or even antagonistic to neutralizing antibodies. We also identify the epitope of a novel group of non-neutralizing antibodies that significantly reduce the speed of red blood cell invasion by the merozoite,thereby potentiating the effect of all neutralizing PfRH5 antibodies as well as synergizing with antibodies targeting other malaria invasion proteins. Our results provide a roadmap for structure-guided vaccine development to maximize antibody efficacy against blood-stage malaria. View Publication

Chronic hepatitis C virus (HCV) infection causes generalized CD8+ T cell impairment,not limited to HCV-specific CD8+ T-cells. Liver-infiltrating monocyte-derived macrophages (MDMs) contribute to the local micro-environment and can interact with and influence cells routinely trafficking through the liver,including CD8+ T-cells. MDMs can be polarized into M1 (classically activated) and M2a,M2b,and M2c (alternatively activated) phenotypes that perform pro- and anti-inflammatory functions,respectively. The impact of chronic HCV infection on MDM subset functions is not known. Our results show that M1 cells generated from chronic HCV patients acquire M2 characteristics,such as increased CD86 expression and IL-10 secretion,compared to uninfected controls. In contrast,M2 subsets from HCV-infected individuals acquired M1-like features by secreting more IL-12 and IFN-gamma. The severity of liver disease was also associated with altered macrophage subset differentiation. In co-cultures with autologous CD8+ T-cells from controls,M1 macrophages alone significantly increased CD8+ T cell IFN-gamma expression in a cytokine-independent and cell-contact-dependent manner. However,M1 macrophages from HCV-infected individuals significantly decreased IFN-gamma expression in CD8+ T-cells. Therefore,altered M1 macrophage differentiation in chronic HCV infection may contribute to observed CD8+ T-cell dysfunction. Understanding the immunological perturbations in chronic HCV infection will lead to the identification of therapeutic targets to restore immune function in HCV+ individuals,and aid in the mitigation of associated negative clinical outcomes. View Publication

Cytokine responses from monocytes and macrophages exposed to bacteria are of particular importance in innate immunity. Focusing on the impact of the immunoregulatory cytokine interleukin (IL)-27 on control of innate immune system responses,we examined human immune responses to bacterial products and bacterial infection by E. coli and S. typhimurium. Since the effect of IL-27 treatment in human myeloid cells infected with bacteria is understudied,we treated human monocytes and macrophages with IL-27 and either LPS,flagellin,or bacteria,to investigate the effect on inflammatory signaling and cytokine responses. We determined that simultaneous stimulation with IL-27 and LPS derived from E. coli or S. typhimurium resulted in enhanced IL-12p40,TNF-$\alpha$,and IL-6 expression compared to that by LPS alone. To elucidate if IL-27 manipulated the cellular response to infection with bacteria,we infected IL-27 treated human macrophages with S. typhimurium. While IL-27 did not affect susceptibility to S. typhimurium infection or S. typhimurium-induced cell death,IL-27 significantly enhanced proinflammatory cytokine production in infected cells. Taken together,we highlight a role for IL-27 in modulating innate immune responses to bacterial infection. View Publication