技术资料

Lentiviral vectors are the method of choice for stable gene modification of a variety of cell types. However,the efficiency with which they transduce target cells varies significantly,in particular their typically poor capacity to transduce primary stem cells. Here we describe the isolation and enrichment of murine bone-marrow mesenchymal stem cells (MSCs) via fluorescence-activated cell sorting (FACS); the cloning,production,and concentration of high-titer second generation lentiviral vectors via combined tangential flow filtration (TFF) and ultracentrifugation; and the subsequent high-efficiency gene modification of MSCs into insulin-producing cells via overexpression of the furin-cleavable human insulin (INS-FUR) gene. View Publication

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

The types and magnitude of Ag-specific immune responses can be determined by the functional plasticity of dendritic cells (DCs). However,how DCs display functional plasticity and control host immune responses have not been fully understood. In this study,we report that ligation of DC-asialoglycoprotein receptor (DC-ASGPR),a C-type lectin receptor (CLR) expressed on human DCs,resulted in rapid activation of Syk,followed by PLCgamma2 and PKCdelta engagements. However,different from other Syk-coupled CLRs,including Dectin-1,signaling cascade through DC-ASGPR did not trigger NF-kappaB activation. Instead,it selectively activated MAPK ERK1/2 and JNK. Rapid and prolonged phosphorylation of ERK1/2 led to sequential activation of p90RSK and CREB,which consequently bound to IL10 promoter and initiated cytokine expression. In addition,DC-ASGPR ligation activated Akt,which differentially regulated the activities of GSK-3alpha/beta and beta-catenin and further contributed to IL-10 expression. Our observations demonstrate that DC-ASGPR induces IL-10 expression via an intrinsic signaling pathway,which provides a molecular explanation for DC-ASGPR-mediated programing of DCs to control host immune responses. View Publication

Emerging evidence suggests an immunosuppressive role of altered tumor glycosylation due to downregulation of innate immune responses via immunoregulatory Siglecs. In contrast,human T cells,a major anticancer effector cell,only rarely express Siglecs. However,here,we report that the majority of intratumoral,but not peripheral blood,cytotoxic CD8+ T cells expressed Siglec-9 in melanoma. We identified Siglec-9+ CD8+ T cells as a subset of effector memory cells with high functional capacity and signatures of clonal expansion. This cytotoxic T-cell subset was functionally inhibited in the presence of Siglec-9 ligands or by Siglec-9 engagement by specific antibodies. TCR signaling pathways and key effector functions (cytotoxicity,cytokine production) of CD8+ T cells were suppressed by Siglec-9 engagement,which was associated with the phosphorylation of the inhibitory protein tyrosine phosphatase SHP-1,but not SHP-2. Expression of cognate Siglec-9 ligands was observed on the majority of tumor cells in primary and metastatic melanoma specimens. Targeting the tumor-restricted,glycosylation-dependent Siglec-9 axis may unleash this intratumoral T-cell subset,while confining T-cell activation to the tumor microenvironment. View Publication

Helminthic infections modulate host immunity and may protect their hosts from developing immunological diseases like inflammatory bowel disease. Induction of regulatory T cells (Tregs) may be an important part of this protective process. Heligmosomoides polygyrus bakeri infection also promotes the production of the regulatory cytokines TGF-beta and IL-10 in the gut. In the intestines,TGF-beta helps induce regulatory T cells. This study used Foxp3/IL-10 double reporter mice to investigate the effect of TGF-beta on the differentiation of colon and mesenteric lymph node-derived murine Foxp3- IL-10- CD4+ T cells into their regulatory phenotypes. Foxp3- IL-10- CD4+ T cells from H. polygyrus bakeri-infected mice,as opposed to T cells from uninfected animals,cultured in vitro with TGF-beta and anti-CD3/CD28 mAb differentiated into Foxp3+ and/or IL-10+ T cells. The IL-10-producing T cells nearly all displayed CD25. Smad7 is a natural inhibitor of TGF-beta signaling. In contrast to gut T cells from uninfected mice,Foxp3- IL10- CD4+ T cells from H. polygyrus bakeri-infected mice displayed reduced Smad7 expression and responded to TGF-beta with Smad2/3 phosphorylation. The TGF-beta-induced Tregs that express IL-10 blocked colitis when transferred into the Rag/CD25- CD4+ T cell transfer model of inflammatory bowel disease. TGF-beta had a greatly diminished capacity to induce Tregs in H. polygyrus bakeri-infected transgenic mice with constitutively high T cell-specific Smad7 expression. Thus,infection with H. polygyrus bakeri causes down-modulation in Smad7 expression in intestinal CD4+ T cells,which allows the TGF-beta produced in response to the infection to induce the Tregs that prevent colitis. View Publication

The maintenance of homeostasis in the gut is a major challenge for the immune system. Here we demonstrate that the transcription factor MAF plays a central role in T cells for the prevention of gastro-intestinal inflammation. Conditional knock out mice lacking Maf in all T cells developed spontaneous late-onset colitis,correlating with a decrease of FOXP3+RORgammat+ T cells proportion,dampened IL-10 production in the colon and an increase of inflammatory TH17 cells. Strikingly,FOXP3+ specific conditional knock out mice for MAF did not develop colitis and demonstrated normal levels of IL-10 in their colon,despite the incapacity of regulatory T cells lacking MAF to suppress colon inflammation in Rag1-/- mice transferred with na{\{i}}ve CD4+ T cells. We showed that one of the cellular sources of IL-10 in the colon of these mice are TH17 cells. Thus MAF is critically involved in the maintenance of the gut homeostasis by regulating the balance between Treg and TH17 cells either at the level of their differentiation or through the modulation of their functions." View Publication

CD4 T cells play a critical role in promoting the development of autoimmunity in type 1 diabetes. The diabetogenic CD4 T cell clone BDC-2.5,originally isolated from a NOD mouse,has been widely used to study the contribution of autoreactive CD4 T cells and relevant Ags to autoimmune diabetes. Recent work from our laboratory has shown that the Ag for BDC-2.5 T cells is a hybrid insulin peptide (2.5HIP) consisting of an insulin C-peptide fragment fused to a peptide from chromogranin A (ChgA) and that endogenous 2.5HIP-reactive T cells are major contributors to autoimmune pathology in NOD mice. The objective of this study was to determine if poly(lactide-co-glycolide) (PLG) nanoparticles (NPs) loaded with the 2.5HIP Ag (2.5HIP-coupled PLG NPs) can tolerize BDC-2.5 T cells. Infusion of 2.5HIP-coupled PLG NPs was found to prevent diabetes in an adoptive transfer model by impairing the ability of BDC-2.5 T cells to produce proinflammatory cytokines through induction of anergy,leading to an increase in the ratio of Foxp3+ regulatory T cells to IFN-gamma+ effector T cells. To our knowledge,this work is the first to use a hybrid insulin peptide,or any neoepitope,to re-educate diabetogenic T cells and may have significant implications for the development of an Ag-specific therapy for type 1 diabetes patients. View Publication

In the inner ear,endolymph fluid surrounds the organ of Corti,which is important for auditory function; notably,even slight environmental changes mediated by trauma or infection can have significant consequences. However,it is unclear how the immune response is modulated in these tissues. Here,we report the local immune surveillance role of cleaved cochlin LCCL (Limulus factor C,Cochlin,and Lgl1) during Pseudomonas aeruginosa infection in the cochlea. Upon infection,the LCCL domain is cleaved from cochlin and secreted into the perilymph. This cleaved fragment sequesters infiltrating bacteria in the scala tympani and subsequently recruits resident immune cells to eliminate the bacteria. Importantly,hearing loss in a cochlin knockout mouse model is remedied by treatment with a cochlin LCCL peptide. These findings suggest cleaved cochlin LCCL constitutes a critical factor in innate immunity and auditory function and may be a potential therapeutic target to treat chronic otitis media-induced hearing loss. View Publication

Acute inflammatory bowel disease (AIBD) is a wide clinical entity including severe gastrointestinal pathologies with common histopathological basis. Epidemiologically increasing diseases,such as necrotizing enterocolitis (NEC),gastrointestinal graft versus host disease (GVHD),and the primary acute phase of chronic inflammatory bowel disease (CIBD),exhibit a high necessity for new therapeutic strategies. Mesenchymal stem cell (MSC) cellular therapy represents a promising option for the treatment of these diseases. In our study,we comparatively assess the efficacy of human MSCs derived from bone marrow (BM),umbilical cord blood (UCB),human embryonic stem cells (ESCs),or human-induced pluripotent stem cells (iPSCs) in a mouse model of chemically induced acute enterocolitis. The laboratory animals were provided ad libitum potable dextrane sulfate sodium solution (DSS) in order to reproduce an AIBD model and then individually exposed intraperitoneally to MSCs derived from BM (BM-MSCs),UCB (UCB-MSCs),ESCs (ESC-MSCs),or iPSCs (iPSC-MSCs). The parameters used to evaluate the cellular treatment efficacy were the animal survival prolongation and the histopathological-macroscopic picture of bowel sections. Although all categories of mesenchymal stem cells led to statistically significant survival prolongation compared to the control group,significant clinical and histopathological improvement was observed only in mice receiving BM-MSCs and UCB-MSCs. Our results demonstrated that the in vivo anti-inflammatory effect of ESC-MSCs and iPSC-MSCs was inferior to that of UCB-MSCs and BM-MSCs. Further investigation will clarify the potential of ESCs and iPSC-derived MSCs in AIBD treatment. View Publication

Broad use of CRISPR-Cas12a (formerly Cpf1) nucleases1 has been hindered by the requirement for an extended TTTV protospacer adjacent motif (PAM)2. To address this limitation,we engineered an enhanced Acidaminococcus sp. Cas12a variant (enAsCas12a) that has a substantially expanded targeting range,enabling targeting of many previously inaccessible PAMs. On average,enAsCas12a exhibits a twofold higher genome editing activity on sites with canonical TTTV PAMs compared to wild-type AsCas12a,and we successfully grafted a subset of mutations from enAsCas12a onto other previously described AsCas12a variants3 to enhance their activities. enAsCas12a improves the efficiency of multiplex gene editing,endogenous gene activation and C-to-T base editing,and we engineered a high-fidelity version of enAsCas12a (enAsCas12a-HF1) to reduce off-target effects. Both enAsCas12a and enAsCas12a-HF1 function in HEK293T and primary human T cells when delivered as ribonucleoprotein (RNP) complexes. Collectively,enAsCas12a provides an optimized version of Cas12a that should enable wider application of Cas12a enzymes for gene and epigenetic editing. View Publication