技术资料

Neural stem cells (NSCs) possess immunosuppressive characteristics,but effects of NSCs on human dendritic cells (DCs),the most important antigen presenting cells,are less well studied. We used an in vitro approach to evaluate the effects of human NSCs on differentiation of human blood CD14+ monocytes into DCs. NSCs derived from H1 human embryonic stem cells (hESC-NSCs) and human ReNcell NSC line,as well as human bone marrow derived mesenchymal stem cells (MSCs),were tested. We observed that in response to treatment with interleukin-4 and granulocyte macrophage colony-stimulating factor CD14+ monocytes co-cultured with NSCs were able to down-regulate CD14 and up-regulate the differentiation marker CD1a,whereas MSC co-culture strongly inhibited CD1a expression and supported prolonged expression of CD14. A similar difference between NSCs and MSCs was noted when lipopolysaccharides were included to induce maturation of monocyte-derived DCs. However,when effects on the function of derived DCs were investigated,NSCs suppressed the elevation of the DC maturation marker CD83,although not the up-regulation of costimulatory molecules CD80,CD86 and CD40,and impaired the functional capacity of the derived DCs to stimulate alloreactive T cells. We did not observe any obvious difference between hESC-NSCs and ReNcell NSCs in inhibiting DC maturation and function. Our data suggest that although human NSCs are less effective than human MSCs in suppressing monocyte differentiation into DCs,these stem cells can still affect the function of DCs,ultimately regulating specific immune responses. View Publication

Mast cells (MCs) play an important role in the regulation of protective adaptive immune responses against pathogens. However,it is still unclear whether MCs promote such host defense responses via direct effects on T cells or rather by modifying the functions of antigen-presenting cells. To identify the underlying mechanisms of the immunoregulatory capacity of MCs,we investigated the impact of MCs on dendritic cell (DC) maturation and function. We found that murine peritoneal MCs underwent direct crosstalk with immature DCs that induced DC maturation as evidenced by enhanced expression of costimulatory molecules. Furthermore,the MC/DC interaction resulted in the release of the T-cell modulating cytokines IFN-γ,IL-2,IL-6 and TGF-β into coculture supernatants and increased the IL-12p70,IFN-γ,IL-6 and TGF-β secretion of LPS-matured DCs. Such MC-primed" DCs subsequently induced efficient CD4+ T-cell proliferation. Surprisingly� View Publication

New vaccines against pertussis are needed to evoke full protection and long-lasting immunological memory starting from the first administration in neonates--the major target of the life-threatening pertussis infection. A novel live attenuated Bordetella pertussis vaccine strain,BPZE1,has been developed by eliminating or detoxifying three important B. pertussis virulence factors: pertussis toxin,dermonecrotic toxin,and tracheal cytotoxin. We used a human preclinical ex vivo model based on monocyte-derived dendritic cells (MDDCs) to evaluate BPZE1 immunogenicity. We studied the effects of BPZE1 on MDDC functions,focusing on the impact of Bordetella-primed dendritic cells in the regulation of Th and suppressor T cells (Ts). BPZE1 is able to activate human MDDCs and to promote the production of a broad spectrum of proinflammatory and regulatory cytokines. Moreover,conversely to its parental wild-type counterpart BPSM,BPZE1-primed MDDCs very efficiently migrate in vitro in response to the lymphatic chemokine CCL21,due to the inactivation of pertussis toxin enzymatic activity. BPZE1-primed MDDCs drove a mixed Th1/Th17 polarization and also induced functional Ts. Experiments performed in a Transwell system showed that cell contact rather than the production of soluble factors was required for suppression activity. Overall,our findings support the potential of BPZE1 as a novel live attenuated pertussis vaccine,as BPZE1-challenged dendritic cells might migrate from the site of infection to the lymph nodes,prime Th cells,mount an adaptive immune response,and orchestrate Th1/Th17 and Ts responses. View Publication

B cell activation and Ab production in response to protein Ags requires presentation of peptides for recruitment of T cell help. We and others have recently demonstrated that B cells can also acquire innate help by presenting lipid Ags via CD1d to NKT cells. Given the newfound contribution of NKT cells to humoral immunity,we sought to identify the pathways that regulate CD1 molecule expression in human B cells. We show that ex vivo,activated and memory B cells expressed lower levels of CD1d compared with resting,naive,and marginal zone-like B cells. In vitro,CD1d was downregulated by all forms of B cell activation,leaving a narrow temporal window in which B cells could activate NKT cells. CD1c expression and function also decreased following activation by CD40L alone,whereas activation via the BCR significantly upregulated CD1c,particularly on marginal zone-like B cells. We found that the CD40L-induced downregulation of CD1d and CD1c correlated with diminished expression of retinoic acid receptor α (RARα) response genes,an effect that was reversed by RARα agonists. However,BCR-induced upregulation of CD1c was independent of the RAR pathway. Our findings that both CD1d and CD1c are upregulated by RARα signaling in human B cells is distinct from effects reported in dendritic cells,in which CD1c is inversely downregulated. One functional consequence of CD1d upregulation by retinoic acid was NKT cell cytotoxicity toward B cells. These results are central to our understanding of how CD1-restricted T cells may control humoral immunity. View Publication

Chylomicron remnants (CMRs) contribute directly to human monocyte activation in vitro,by increasing reactive oxygen species (ROS) production and cell migration. In this study,the effects of the oxidative state of CMR on the degree of monocyte activation was investigated. CMR-like particles (CRLPs) were prepared in three different oxidative states,normal (CRLPs),protected from oxidation by incorporation of the antioxidant,probucol (pCRLPs),or oxidised with CuSO(4) (oxCRLPs). Lipid accumulation and ROS production were significantly increased in primary human monocytes incubated with CRLPs,whilst secretion on monocyte chemoattractant protein-1 was reduced,but oxCRLPs had no additional effect. In contrast,pCRLPs were taken up by monocytes to a lesser extent and had no significant effect on ROS or MCP-1 secretion. These studies suggest that the oxidative state of CMRs modulates their stimulation of the activation of peripheral blood human monocytes and that dietary antioxidants may provide some protection against these atherogenic effects. View Publication