技术资料

The presentation of proteins on surfaces is fundamental to numerous cell culture and tissue engineering applications. While a number of physisorption and cross-linking methods exist to facilitate this process,few avoid denaturation of proteins or allow control over protein orientation,both of which are critical to the functionality of many signal proteins and ligands. Often recombinant protein sequences include a poly-histidine tag to facilitate purification. We utilize this sequence to anchor proteins to biosurfaces via a peptide bonded to the surface which conjugates with the poly-histidine tag in the presence of zinc rather than nickel,which is more traditionally used to conjugate poly-histidine tags to surfaces. We demonstrate that this strategy enables the display of proteins on 2D and 3D surfaces without compromising protein function through direct cross-linking or physisorption. View Publication

TNF-like ligand 1A (TL1A),a member of the TNF superfamily,is the ligand of DR3 and DcR3. Several types of cells,such as endothelial cells,monocytes/macrophages,dendritic cells,and CD4 and CD8 T cells,are capable of producing this cytokine. In present study,we demonstrated that TL1A aggravated collagen-induced arthritis in mice. It increased collagen-induced arthritis penetrance and clinical scores as well as the severity of the pathological findings. TL1A administration led to the occurrence of multiple enlarged germinal centers in the spleen,and it boosted serum anti-collagen Ab titers in vivo. In vitro,TL1A augmented TNF-alpha production by T cells upon TCR ligation,and it greatly enhanced Th17 differentiation and IL-17 production. We further showed that human rheumatoid arthritis (RA) synovial fluids had elevated TL1A titers,and human chrondrocytes and synovial fibroblasts were capable of secreting TL1A upon TNF-alpha or IL-1beta stimulation. Taken together,these data suggest that TL1A secretion in lymphoid organs might contribute to RA initiation by promoting autoantibody production,and TL1A secretion stimulated by inflammatory cytokines in RA joints might be a part of a vicious circle that aggravates RA pathogenesis. View Publication

C57BL/6 (B6) mice are genetically highly susceptible to chronic type II Toxoplasma gondii infections that invariably cause lethal toxoplasmic encephalitis. We examined the ability of an attenuated type I vaccine strain to elicit long-term immunity to lethal acute or chronic type II infections in susceptible B6 mice. Mice immunized with the type I cps1-1 vaccine strain were not susceptible to a lethal (100-cyst) challenge with the type II strain ME49. Immunized mice challenged with 10 ME49 cysts exhibited significant reductions in brain cyst and parasite burdens compared to naive mice,regardless of the route of challenge infection. Remarkably,cps1-1 strain-immunized B6 mice chronically infected with ME49 survived for at least 12 months without succumbing to the chronic infection. Potent immunity to type II challenge infections persisted for at least 10 months after vaccination. While the cps1-1 strain-elicited immunity did not prevent the establishment of a chronic infection or clear established brain cysts,cps1-1 strain-elicited CD8(+) immune T cells significantly inhibited recrudescence of brain cysts during chronic ME49 infection. In addition,we show that uracil starvation of the cps1-1 strain induces early markers of bradyzoite differentiation. Collectively,these results suggest that more effective immune control of chronic type II infection in the genetically susceptible B6 background is established by vaccination with the nonreplicating type I uracil auxotroph cps1-1 strain. View Publication

The active movement of cells from subendothelial compartments into the bloodstream (intravasation) has been recognized for several decades by histologic and physiologic studies,yet the molecular effectors of this process are relatively uncharacterized. For extravasation,studies based predominantly on static transwell assays support a general model,whereby transendothelial migration (TEM) occurs via chemoattraction toward increasing chemokine concentrations. However,this model of chemotaxis cannot readily reconcile how chemokines influence intravasation,as shear forces of blood flow would likely abrogate luminal chemokine gradient(s). Thus,to analyze how T cells integrate perivascular chemokine signals under physiologic flow,we developed a novel transwell-based flow chamber allowing for real-time modulation of chemokine levels above (luminal/apical compartment) and below (abluminal/subendothelial compartment) HUVEC monolayers. We routinely observed human T cell TEM across HUVEC monolayers with the combination of luminal CXCL12 and abluminal CCL5. With increasing concentrations of CXCL12 in the luminal compartment,transmigrated T cells did not undergo retrograde transendothelial migration (retro-TEM). However,when exposedto abluminal CXCL12,transmigrated T cells underwent striking retro-TEM and re-entered the flow stream [corrected]. This CXCL12 fugetactic (chemorepellant) effect was concentration-dependent,augmented by apical flow,blocked by antibodies to integrins,and reduced by AMD3100 in a dose-dependent manner. Moreover,CXCL12-induced retro-TEM was inhibited by PI3K antagonism and cAMP agonism. These findings broaden our understanding of chemokine biology and support a novel paradigm by which temporospatial modulations in subendothelial chemokine display drive cell migration from interstitial compartments into the bloodstream. View Publication

The activating NK cell receptor DNAX accessory molecule-1 (DNAM-1) contributes to tumor immune surveillance and plays a crucial role in NK cell-mediated recognition of several types of human tumors,including ovarian carcinoma. Here,we have analyzed the receptor repertoire and functional integrity of NK cells in peritoneal effusions from patients with ovarian carcinoma. Relative to autologous peripheral blood NK cells,tumor-associated NK cells expressed reduced levels of the DNAM-1,2B4,and CD16 receptors and were hyporesponsive to HLA class I-deficient K562 cells and to coactivation via DNAM-1 and 2B4. Moreover,tumor-associated NK cells were also refractory to CD16 receptor stimulation,resulting in diminished Ab-dependent cellular cytotoxicity against autologous tumor cells. Coincubation of NK cells with ovarian carcinoma cells expressing the DNAM-1 ligand CD155 led to reduction of DNAM-1 expression. Therefore,NK cell-mediated rejection of ovarian carcinoma may be limited by perturbed DNAM-1 expression on tumor-associated NK cells induced by chronic ligand exposure. Thus,these data support the notion that tumor-induced alterations of activating NK cell receptor expression may hamper immune surveillance and promote tumor progression. View Publication

Effector cells derived from central memory CD8(+) T cells were reported to engraft and survive better than those derived from effector memory populations,suggesting that they are superior for use in adoptive immunotherapy studies. However,previous studies did not evaluate the relative efficacy of effector cells derived from naïve T cells. We sought to investigate the efficacy of tumor-specific effector cells derived from naïve or central memory T-cell subsets using transgenic or retrovirally transduced T cells engineered to express a tumor-specific T-cell receptor. We found that naïve,rather than central memory T cells,gave rise to an effector population that mediated superior antitumor immunity upon adoptive transfer. Effector cells developed from naïve T cells lost the expression of CD62L more rapidly than those derived from central memory T cells,but did not acquire the expression of KLRG-1,a marker for terminal differentiation and replicative senescence. Consistent with this KLRG-1(-) phenotype,naïve-derived cells were capable of a greater proliferative burst and had enhanced cytokine production after adoptive transfer. These results indicate that insertion of genes that confer antitumor specificity into naïve rather than central memory CD8(+) T cells may allow superior efficacy upon adoptive transfer. View Publication

Uterine leiomyomas (also known as uterine fibroids) are the most common benign tumors of female reproductive tract and are the single most common indication for hysterectomies. Despite their high prevalence,the exact pathogenesis of these benign tumors is still unknown. One possible mechanism for leiomyoma formation is dysregulation of mesenchymal stem cell activity. Mesenchymal stem cells have been identified in both human and murine uteri and cancer stem cells have been identified in female reproductive malignancies. We compared stem/progenitor cell characteristics in both normal myometrium and the corresponding leiomyoma of patient's undergoing hysterectomies. We found that leiomyoma cells form fewer mesenchymal stem cell colonies and exhibit less Hoechst dye-excluding side population (SP) activity,which is a function associated with progenitor cells in other tissues,than cells isolated from normal myometrium. Whereas in normal myometrium,we observed heterogeneous expression of CD90,a cell surface marker associated the with differentiation potential of uterine fibroblasts,in leiomyomas,we observed homogenous expression of CD90,suggesting leiomyoma cells are more terminally differentiated. Furthermore,we found that while leiomyoma cells could only produce CD90 expressing cells,both CD90+ and CD90- myometrial cells could reestablish their original heterogeneous CD90 profile when expanded in vitro. These results suggest that normal myometrium contains cells with stem/progenitor cell activities that are absent in leiomyomas. View Publication

The lack of natural killer (NK) cell-specific markers,as well as the overlap among several common surface antigens and functional properties,has obscured the delineation between NK cells and dendritic cells. Here,novel subsets of peripheral blood CD3/14/19(neg) NK cells and monocyte/dendritic cell (DC)-like cells were identified on the basis of CD7 and CD4 expression. Coexpression of CD7 and CD56 differentiates NK cells from CD56+ monocyte/DC-like cells,which lack CD7. In contrast to CD7+CD56+ NK cells,CD7(neg)CD56+ cells lack expression of NK cell-associated markers,but share commonalities in their expression of various monocyte/DC-associated markers. Using CD7,we observed approximately 60% of CD4+CD56+ cells were CD7(neg) cells,indicating the actual frequency of activated CD4+ NK cells is much lower in the blood than previously recognized. Functionally,only CD7+ NK cells secrete gamma interferon (IFNgamma) and degranulate after interleukin-12 (IL-12) plus IL-18 or K562 target cell stimulation. Furthermore,using CD7 to separate CD56+ NK cells and CD56+ myeloid cells,we demonstrate that unlike resting CD7+CD56+ NK cells,the CD7(neg)CD56+ myeloid cells stimulate a potent allogeneic response. Our data indicate that CD7 and CD56 coexpression discriminates NK cells from CD7(neg)CD56+ monocyte/DC-like cells,thereby improving our ability to study the intricacies of NK-cell subset phenotypes and functions in vivo. View Publication

The cancer stem cell (CSC) hypothesis implicates the development of new therapeutic approaches to target the CSC population. Characterization of the pathways that regulate CSCs activity will facilitate the development of targeted therapies. We recently reported that the enzymatic activity of ALDH1,as measured by the ALDELFUOR assay,can be utilized to isolate normal and malignant breast stem cells in both primary tumors and cell lines. In this study,utilizing a tumorsphere assay,we have demonstrated the role of retinoid signaling in the regulation of breast CSCs self-renewal and differentiation. Utilizing the gene set enrichment analysis (GSEA) algorithm we identified gene sets and pathways associated with retinoid signaling. These pathways regulate breast CSCs biology and their inhibition may provide novel therapeutic approaches to target breast CSCs. View Publication

Patients with chronic ulcerative colitis are at increased risk of developing colorectal cancer. Although current hypotheses suggest that sporadic colorectal cancer is due to inability to control cancer stem cells,the cancer stem cell hypothesis has not yet been validated in colitis-associated cancer. Furthermore,the identification of the colitis to cancer transition is challenging. We recently showed that epithelial cells with the increased expression of aldehyde dehydrogenase in sporadic colon cancer correlate closely with tumor-initiating ability. We sought to determine whether ALDH can be used as a marker to isolate tumor-initiating populations from patients with chronic ulcerative colitis. We used fluorescence-activated cell sorting to identify precursor colon cancer stem cells from colitis patients and report both their transition to cancerous stem cells in xenografting studies as well as their ability to generate spheres in vitro. Similar to sporadic colon cancer,these colitis-derived tumors were capable of propagation as sphere cultures. However,unlike the origins of sporadic colon cancer,the primary colitic tissues did not express any histologic evidence of dysplasia. To elucidate a potential mechanism for our findings,we compared the stroma of these different environments and determined that at least one paracrine factor is up-regulated in the inflammatory and malignant stroma compared with resting,normal stroma. These data link colitis and cancer identifying potential tumor-initiating cells from colitic patients,suggesting that sphere and/or xenograft formation will be useful to survey colitic patients at risk of developing cancer. View Publication

Human induced pluripotent stem cells (iPSCs) hold promise as a source of adult-derived,patient-specific pluripotent cells for use in cell-based regenerative therapies. However,current methods of cell culture are tedious and expensive,and the mechanisms underlying cell proliferation are not understood. In this study,we investigated expression and function of iPSC integrin extracellular matrix receptors to better understand the molecular mechanisms of cell adhesion,survival,and proliferation. We show that iPSC lines generated using Oct-3/4,Sox-2,Nanog,and Lin-28 express a repertoire of integrins similar to that of hESCs,with prominent expression of subunits alpha5,alpha6,alphav,beta1,and beta5. Integrin function was investigated in iPSCs cultured without feeder layers on Matrigel or vitronectin,in comparison to human embryonic stem cells. beta1 integrins were required for adhesion and proliferation on Matrigel,as shown by immunological blockade experiments. On vitronectin,the integrin alphavbeta5 was required for initial attachment,but inhibition of both alphavbeta5 and beta1 was required to significantly decrease iPSC proliferation. Furthermore,iPSCs cultured on vitronectin for 9 passages retained normal karyotype,pluripotency marker expression,and capacity to differentiate in vitro. These studies suggest that vitronectin,or derivatives thereof,might substitute for Matrigel in a more defined system for iPSC culture. View Publication

The tyrosine kinase Fyn plays a key role in oligodendrocyte differentiation and myelination in the central nervous system,but the molecules responsible for regulating Fyn activation in these processes remain poorly defined. Here we show that receptor-like protein-tyrosine phosphatase alpha (PTPalpha) is an important positive regulator of Fyn activation and signaling that is required for the differentiation of oligodendrocyte progenitor cells (OPCs). PTPalpha is expressed in OPCs and is up-regulated during differentiation. We used two model systems to investigate the role of PTPalpha in OPC differentiation: the rat CG4 cell line where PTPalpha expression was silenced by small interfering RNA,and oligosphere-derived primary OPCs isolated from wild-type and PTPalpha-null mouse embryos. In both cell systems,the ablation of PTPalpha inhibited differentiation and morphological changes that accompany this process. Although Fyn was activated upon induction of differentiation,the level of activation was severely reduced in cells lacking PTPalpha,as was the activation of Fyn effector molecules focal adhesion kinase,Rac1,and Cdc42,and inactivation of Rho. Interestingly,another downstream effector of Fyn,p190RhoGAP,which is responsible for Rho inactivation during differentiation,was not affected by PTPalpha ablation. In vivo studies revealed defective myelination in the PTPalpha(-/-) mouse brain. Together,our findings demonstrate that PTPalpha is a critical regulator of Fyn activation and of specific Fyn signaling events during differentiation,and is essential for promoting OPC differentiation and central nervous system myelination. View Publication