Tumour necrosis factor-alpha production stimulated by heat shock protein 70 and its inhibition in circulating dendritic cells and cells eluted from mucosal tissues in Crohn's disease

Summaryand interleukin (IL)-12 by dendritic cells (DC) from patients with Crohn's disease. TNF-alpha concentration was increased significantly when DC from Crohn's disease were stimulated with HSP70 or CD40L and this was associated with signalling by the extracellular signal regulated kinase (ERK) 1/2 and p38 mitogen activated protein (MAP) kinase pathway. IL-12 production was also increased when DC were stimulated with HSP70. Cells eluted from inflamed intestinal mucosa from Crohn's disease, stimulated with HSP70, CD40L or lipopolysaccharide produced significantly greater TNF-alpha and IL-12 concentrations than cells from uninflamed mucosa. Significant inhibition of TNF-alpha production was demonstrated when DC from peripheral blood mononuclear cells or cells eluted from intestinal mucosa of Crohn's disease were treated with either the HSP70 inhibitory peptide (aa 457-496) or peptides derived from CD40 and CD40L. These inhibitory peptides target the CD40-CD40L and the emerging CD40-HSP70 co-stimulatory pathway. Our findings offer a novel strategy to prevent excessive production of TNF-alpha in Crohn's disease.     

TLR4在HSP70_(EC-TCV)冲激的DC成熟过程中的作用

观察TLR4在Hca-F榄香烯复合瘤苗来源的HSP70(HSP70EC-TCV)冲激处理的小鼠骨髓来源的DC成熟过程中的作用。用rmGM-CSF和rmIL-4诱导小鼠骨髓来源的DC,以HSP70EC-TCV或加入抗TLR4抗体30 min后再用HSP70EC-TCV冲激处理DC,流式细胞仪检测DC的CD40和CD86表达,ELISA法检测DC上清中IL-12和T细胞上清中IL-2浓度,MTT法检测T细胞对Hca-F细胞的杀伤率。结果表明,抗TLR4抗体对DC的CD40和CD86表达无明显影响,但对HSP70EC-TCV诱导DC分泌IL-12和进而致敏的T细胞分泌IL-2及产生杀瘤功能有明显的抑制作用。TLR4信号通路参与HSP70EC-TCV诱导DC成熟过程。     

Differential role of mitogen-activated protein kinases in CD40-mediated IL-12 production by immature and mature dendritic cells

Using a murine spleen-derived dendritic cell (DC) line (BC1) CD40-mediated interleukin (IL)-12 production was analyzed and compared between immature and mature DC. BC1 cells, immature DC (iDC), were maturated by treatment with lipopolysaccharide (LPS) or tumor necrosis factor (TNF)-alpha. IL-12 production of LPS-treated DC (LPS/DC) was markedly enhanced by treatment with an anti-CD40 monoclonal antibody (mAb). Although the anti-CD40 mAb also enhanced IL-12 productions of iDC and TNF-alpha-treated DC (TNF/DC), these production levels were considerably low compared with that of LPS/DC. CD40-mediated IL-12-productions by iDC and TNF/DC were significantly enhanced by treatment with PD98059, a specific inhibitor of extracellular signal-related kinase (ERK) pathway. In contrast, PD98059 showed no significant effects on CD40-mediated IL-12-production by LPS/DC. These results demonstrated that ERK pathway was involved in negative regulation of the IL-12 productions by iDC and TNF/DC but not by LPS/DC. On the other hand, SB203580, a specific inhibitor of p38 mitogen activated protein kinase (MAPK) pathway, completely inhibited CD40-mediated IL-12-production by iDC, while not affecting those of TNF/DC and LPS/DC. Thus, p38 MAPK pathway appeared to positively regulate the IL-12 production in iDC but not in mature DC. It seems that roles of ERK and p38 MAPK for IL-12 production are developmentally changed in murine DC.     

IFN-alpha enhances CD40 ligand-mediated activation of immature monocyte-derived dendritic cells

Type I IFN are immune modulatory cytokines that are secreted during early stages of infection. Type I IFN bridge the innate and the adaptive immune system in humans and mice. We compared the capacity of type I and II IFN to induce the functional maturation of monocyte-derived dendritic cells (MoDC). Extending our earlier observation that type I IFN promote DC maturation, we report that these cytokines also enhance DC differentiation by augmenting CD40 ligand (CD40L)-induced cytokine secretion by MoDC. Type I IFN alone were poor inducers of MoDC maturation as compared with other stimuli. They up-regulated the expression of HLA-DR, CD80, CD86, partially CCR7 but not CD83, partially reduced antigen-uptake function, increased the levels of IL-12p35 mRNA, and prolonged surface expression of peptide-MHC class I complexes for presentation to cytotoxic T lymphocytes, but did not induce migration towards CCL21 chemokine. However, type I IFN were potent co-factors for CD40L-mediated function. Here, they enhanced CD40L-mediated IL-6, IL-10 and IL-12p70 secretion. Furthermore, when combined with IL-1beta and/or IL-4, IFN-alpha2a type I IFN increased CD40L-mediated IL-12p70 production by 2- to 3-fold, and biased the IL-12 p40/p70 ratio towards the IFN-gamma inducing p70 heterodimer, this correlating with higher levels of IFN-gamma secretion by allogeneic T cell subsets and NK cells. Our results suggest that the rapid expression of CD40L, IFN and IL-1beta at sites of infection and inflammation can act in concert on immature DC, thereby linking innate and adaptive immune responses. In this way, type I IFN play a dual role as DC maturation factors and enhancers of CD40L-mediated DC activation.     

Requirement of the extracellular cysteine at position six for CD40/CD40 dimer formation and CD40-induced IL-8 expression

We recently showed that oligomerization of CD40 molecules on cell surface leads to disulfide-linked CD40/CD40 dimer formation, an event that is necessary for CD40-induced B7-2 expression in human B cells. Here, we demonstrate that CD40/CD40 dimers formation also occurs in different cell types such as T24 bladder cancer cells and CD40-transfected HEK 293 cells. Disulfide bonds mediate the formation of CD40/CD40 homodimers in CD40-activated cells. To determine the potential residue(s) involved in disulfide bonds formation and subsequent CD40-induced IL-8 expression, we generated a CD40 mutant in which the extracellular cysteine 6 was replaced by a glutamine (CD40-C6Q). CD40-induced IL-8 mRNA expression and protein synthesis were studied in stably transfected HEK 293 cells that were sorted out along with similar levels of expression of wild type (CD40-WT) and CD40-C6Q molecules. In contrast to cells expressing CD40-WT protein, disulfide-linked CD40/CD40 dimer formation was completely abolished in HEK 293 cells expressing CD40-C6Q proteins. Abolishment of disulfide-linked CD40/CD40 dimers in these transfected cells was sufficient to inhibit CD40-induced mRNA expression and secretion of IL-8. This study identifies the extracellular cysteine 6 of CD40 molecules as a potential molecular target to disrupt the expression of CD40-induced pro-inflammatory cytokines by epithelial cells.     

Interferon-gamma is an autocrine mediator for dendritic cell maturation

Maturation of dendritic cells (DC) is critical for efficient antigen presentation and initiation of an immune response. Interferon-gamma (IFN-gamma) is an important Th1 cytokine. In this study, we investigated the role of IFN-gamma in DC maturation using either IFN-gamma receptor deficient- or IFN-gamma overexpression-models. We showed that immature DC generated in vitro from bone marrow (BM) progenitor cells produced low level of IFN-gamma. After LPS stimulation, DC produced more IFN-gamma, and IFN-gamma productions were at comparable levels among C57BL/6 mice-derived DC (C57BL/6 DC), wild-type 129 mice-derived DC (129 DC) and IFN-gamma receptor deficient 129 mice-derived DC (IFN-gammaR-/-DC). We found that IFN-gammaR-/-DC exhibited decreased expression of CD54, CD86, reduced capacity to secrete IL-1beta and IL-12p70, and impaired capacity to stimulate alloreactive T cells and to drive Th1 differentiation. Transfection of IFN-gamma gene into DC promoted DC to express higher CD40, CD54, CD80, CD86, CCR7 and I-Ab, secrete more IL-1beta and IL-12p70, and more potently activate both CD4 and CD8 T cells. These data suggest that IFN-gamma signaling pathway is important for the maturation of DC in an autocrine fashion.     

Distinct regulation of CD40-mediated interleukin-6 and interleukin-12 productions via mitogen-activated protein kinase and nuclear factor kappaB-inducing kinase in mature dendritic cells

The role of mitogen-activated protein kinase (MAPK) and nuclear factor kappaB (NF-kappaB) pathways, especially NF-kappaB-inducing kinase (NIK)-mediated alternative pathway, in CD40-mediated interleukin (IL)-6 and IL-12 productions by immature or mature dendritic cells (DCs) was investigated. Murine myeloid DCs were matured by treatment with lipopolysaccharide. CD40 ligation induced modest or vigorous cytokine productions in immature or mature DCs, respectively. After CD40 ligation, p38 MAPK was significantly activated in either immature or mature DCs. SB203580, a p38 MAPK inhibitor, markedly decreased CD40-mediated IL-6 and IL-12 productions in immature DCs. In mature DCs, SB203580 significantly decreased CD40-mediated IL-6 but not IL-12 production. On the other hand, CD40 ligation induced vigorous activation of the NF-kappaB alternative pathway including p100 phosphorylation and subsequent nuclear translocations of p52, a processed form of p100, and RelB in mature but not immature DCs. The CD40-mediated phosphorylation of p100 was completely abolished in NIK-mutated mature DCs. The NIK mutation markedly reduced CD40-mediated IL-12 but not IL-6 production by mature DCs. Taken together, we concluded that IL-6 and IL-12 productions in response to CD40 ligation were controlled by p38 MAPK and NIK mediated alternative pathway, respectively, in mature DCs.     

Mouse CD40-transfected cell lines cannot exhibit the binding and RANTES-stimulating activity of exogenous heat shock protein 70

Here we demonstrate the inducible mouse Hsp72 binds markedly to lymphoid neoplastic macrophage-like P388D1 cells. To examine whether mouse CD40 can play a role in signaling exogenously administered HSP70 in a fashion similar to that of human CD40, we established mouse CD40-transfectants of both human 293 cells and murine-pro-B cell line Ba/F3. A small portion of mouse CD40 expressed on 293-derived transfectants was the mature form with a signal-transducible C-terminal domain, whereas a majority of expressed antigen showed the molecular size smaller than we expect. Flow cytometry showed that mouse Hsp72, but neither its deletion variants nor the related Escherichia coli DnaK, bound to the 293-derived transfectants regardless of CD40 expression. CD40 molecules expressed on the transfectants showed the binding of soluble form of CD40L but this binding was not inhibited by excess amount of HSP70. CD40L, but not any HSP70 recombinant proteins, stimulated the production of chemokine RANTES in the transfectants. Furthermore, no RANTES production was induced by HSP70-RCMLA complex in the transfectants, although it binds to 293-derived cells in a CD40-independent manner. No interaction between mouse CD40 and HSP70 recombinant proteins was detected by using the Ba/F3-derived transfectants that express the mature form of mouse CD40. The present results imply that mouse CD40 expressed on the transfectants differs from its human homolog in the binding of exogenously administered HSP70.     

CD40L-expressing CD8 T cells prime CD8alpha(+) DC for IL-12p70 production

CD8alpha(+) DC are implicated as the principle DC subset for cross-presentation and cross-priming of cytotoxic CD8 T cell responses. In this study, we demonstrate another unique facet of the CD8alpha(+) DC and CD8 T cell relationship, by showing that CD8 T cells reciprocally activate CD8alpha(+) DC, but not CD8alpha(-) DC, for IL-12p70 production, the key Th1-promoting cytokine. This effect was observed during an antigen-specific interaction between DC and activated CD8 T cells, along with secondary TLR stimulation of DC by LPS. Activated CD8 T cells use a combination of IFN-gamma and CD40L, which is rapidly up-regulated post-stimulation, to prime DC for IL-12p70 production during an antigen-specific response. Our results suggest that the interaction between CD8alpha(+) DC and antigen-primed CD8 T cells may form an important component of Th1-mediated immunity through the induction of IL-12p70.     

Phosphodiesterase 4 inhibitors reduce human dendritic cell inflammatory cytokine production and Th1-polarizing capacity

Inhibitors of cAMP-specific phosphodiesterase (PDE) 4 have been shown to inhibit inflammatory mediator release and T cell proliferation, and are considered candidate therapies for T(h)1-mediated diseases. However, little is known about how PDE4 inhibitors influence dendritic cells (DC), the cells responsible for the priming of naive T(h) cells. Therefore, we investigated the PDE profile of monocyte-derived DC, and whether PDE4 inhibitors modulate DC cytokine production and T cell-polarizing capacity. We mainly found cAMP-specific PDE4 enzymatic activity in both immature and mature DC. In contrast to monocytes that mainly express PDE4B, we found that PDE4A is the predominant PDE4 subtype present in DC. Immature DC showed reduced ability to produce IL-12p70 and tumor necrosis factor (TNF)-alpha upon lipopolysaccharide or CD40 ligand (CD40L) stimulation in the presence of PDE4 inhibitors, whereas cytokine production upon CD40L stimulation of fully mature DC in the presence of PDE4 inhibitors was not affected. Exposure to PDE4 inhibitors for 2 days during DC maturation did not influence T cell-stimulatory capacity or acquisition of a mature phenotype, but increased the expression of the chemokine receptor CXCR4. Furthermore, DC matured in the presence of PDE4 inhibitors showed reduced capacity to produce IL-12p70 and TNF-alpha upon subsequent CD40L stimulation. Using these PDE4 inhibitor-matured DC to stimulate naive T cells resulted in a reduction of IFN-gamma-producing (T(h)1) cells. These findings indicate that PDE4 inhibitors can affect T cell responses by acting at the DC level and may increase our understanding of the therapeutic implication of PDE4 inhibitors for T(h)1-mediated disorders.     

The role of heat shock protein (hsp70) in dendritic cell maturation: hsp70 induces the maturation of immature dendritic cells but reduces DC differentiation from monocyte precursors

Members of the heat shock protein (hsp70) family are either constitutively expressed (hsc70) or can be induced by hyperthermic stress (hsp70). Recombinant hsp70 (rhsp70) stimulates cytokine production from monocytes and enhances NK cell proliferation and cytotoxicity. Here we demonstrate that rhsp70 binds to immature dendritic cells (DC) derived from monocyte precursors and induces their maturation as evidenced by an increase in CD40, CD86 and CD83 expression. Immature DC stimulated to mature with rhsp70 show an enhanced ability to present tyrosinase peptide to specific CTL. Mature DC did not bind rhsp70, suggesting a down-regulation in the expression of its receptor. When rhsp70 was added to monocyte precursors at the same time as GM-CSF and IL-4 it reduced the differentiation of monocytes into DC as shown by a decrease in the level of CD40, CD83, CD86 and HLA-DR expression and an increase in CD14 expression. The constitutively expressed hsc70 had neither a stimulatory effect on the maturation of immature DC nor did it reduce the differentiation of monocytes into DC. These findings demonstrate the specific ability of rhsp70 to induce the maturation of immature DC. Therefore rhsp70 may be useful for its adjuvant like properties in DC based immunotherapy of certain tumors.     

Combined use of toll-like receptor agonists and prostaglandin E(2) in the FastDC model: rapid generation of human monocyte-derived dendritic cells capable of migration and IL-12p70 production

Phenotypical maturation, IL-12p70 production and migration upon chemokine receptor CCR7 ligation are currently proposed as requirements for the use of human monocyte-derived dendritic cells (DC) in antitumoral vaccination. We have previously described a short-term protocol for DC generation from monocytes including stimulation with TNF-alpha, IL-1beta and PGE(2) (FastDC). These "conventional" FastDC are mature, migrate in response to CCR7 ligation and effectively stimulate autologeous T cells in vitro, but are deficient in IL-12p70 production. Here, conventional FastDC were compared to FastDC activated with different TLR ligands. High levels of IL-12p70 were induced by combined activation of FastDC with TLR4 and TLR7/8 ligands. IL-12 secretion could be maximized by additional T cell-derived stimulation. However, TLR-stimulated FastDC failed to migrate upon CCR7 ligation, independent of additional activation with CD40 ligand and IFN-gamma. The presence of PGE(2) during TLR ligation fully restored migratory capacity of FastDC, but left IL-12p70 production and activation of tumor antigen-specific cytotoxic T cells unaffected, challenging previous findings obtained with standard 7-day monocyte-derived DC. The FastDC model thus not only represents an effective tool for antitumoral vaccination, but may also provide novel insights into human DC biology.     

Maturation of dendritic cells for enhanced activation of anti-HIV-1 CD8(+) T cell immunity

Maturation of dendritic cells (DC) to enhance their capacity to activate T cell immunity to HIV-1 is a key step in immunotherapy of HIV-1 infection with DC. We compared maturation of DC derived from HIV-1-uninfected subjects and infected subjects on antiretroviral therapy (ART) or ART na?ve by CD40 ligand (CD40L) and combinations of TLR3 ligand polyinosinic:polycytidylic acid [poly(I:C)] and inflammatory cytokines IFN-gamma, IFN-alpha, IL-1beta, and TNF-alpha. The greatest levels of virus-specific IFN-gamma production by CD8(+) T cells were stimulated by DC treated with CD40L, followed by DC treated with the poly(I:C)-cytokine combination. The highest levels of IL-12p70 were produced by DC treated with CD40L + IFN-gamma, followed by CD40L and the poly(I:C)-cytokine combination. Neutralization of IL-12p70 indicated that it was only partially involved in direct enhancement of antiviral CD8(+) T cell activity. DC stimulation of antiviral CD8(+) T cell reactivity was enhanced by activated CD4(+) T cells at low concentrations but was suppressed at higher CD4(+) T cell concentrations. Maturation of DC with CD40L obviated the need for CD4(+) T cell help and overcame this suppressive activity. Finally, we showed that DC from HIV-1-infected subjects on ART, which were treated with the poly(I:C)-cytokine combination, retained the capacity to produce IL-12p70 and activate anti-HIV-1 CD8(+) T cell responses after restimulation with CD40L, with or without IFN-gamma. Thus, DC from HIV-1-infected subjects can be engineered with CD40L or a poly(I:C)-cytokine combination for enhancing CD8(+) T cell responses to HIV-1, which has potential applications in HIV-1 immunotherapy.     

Polysaccharide purified from Ganoderma lucidum induced activation and maturation of human monocyte-derived dendritic cells by the NF-kappaB and p38 mitogen-activated protein kinase pathways

Ganoderma lucidum, a fungus native to China, has been widely used to promote health and longevity in the Chinese. The polysaccharide component with a branched (1-->6)-beta-D-glucan moiety of G. lucidum (PS-G) has been reported to exert anti-tumor activity and activation of natural killer cells. In this study, we investigated the effects of PS-G on human monocyte-derived dendritic cells (DC). Treatment of DC with PS-G resulted in the enhanced cell-surface expression of CD80, CD86, CD83, CD40, CD54, and human leukocyte antigen (HLA)-DR, as well as the enhanced production of interleukin (IL)-12p70, p40, and IL-10 and also IL-12p35, p40, and IL-10 mRNA expression, and the capacity for endocytosis was suppressed in DC. In addition, treatment of DC with PS-G resulted in enhanced T cell-stimulatory capacity and increased T cell secretion of interferon-gamma and IL-10. Neutralization with antibodies against Toll-like receptor (TLR)-4 inhibited the PS-G-induced production of IL-12 p40 and IL-10, suggesting a vital role for TLR-4 in signaling DC upon incubation with PS-G. Further study showed that PS-G was able to augment inhibitor of kappaB (IkappaB) kinase and nuclear factor (NF)-kappaB activity and also IkappaB alpha and p38 mitogen-activated protein kinase (MAPK) phosphorylation. Further, inhibition of NF-kappaB by helenalin and p38 MAPK by SB98059 prevented the effects of PS-G in the expression of CD80, CD86, CD83, CD40, CD54, and HLA-DR and production of IL-12p70, p40, and IL-10 in various degrees. Taken together, our data demonstrate that PS-G can effectively promote the activation and maturation of immature DC, suggesting that PS-G may possess a potential in regulating immune responses.     

Immature macrophages derived from mouse bone marrow produce large amounts of IL-12p40 after LPS stimulation

Production of IL-12 is an important indicator of the macrophage's ability to regulate immune responses. In this study, we investigated the IL-12 production by macrophages in different developmental stages. To this end, macrophages were generated in vitro from precursors stimulated with M-CSF, GM-CSF or IL-3. Density separation yielded populations enriched in different maturation stages. Invariably, only cells banding at the 40-50% Percoll interface produced large amounts of IL-12p40 when stimulated with LPS, whereas only low levels of IL-12p70 were produced. These cells represented immature macrophages, as indicated by the absence of precursor markers CD31/ER-MP12, Ly-6C/ER-MP20 and ER-MP58, and by the low level of expression of mature-cell markers like ER-HR3, scavenger receptor and CD11b/Mac-1. Upon further maturation, the macrophages' ability to produce IL-12p40 decreased, coinciding with increased nitric oxide production upon LPS stimulation. These results show that immature macrophages produce high levels of IL-12p40 and thus may either contribute to IL-12p70 production or regulate it.     

Role of CCR1 and CCR5 in homing and growth of multiple myeloma and in the development of osteolytic lesions: a study in the 5TMM model

Multiple myeloma (MM) is a plasma cell malignancy, characterized by the localization of the MM cells in the bone marrow (BM), where they proliferate and induce osteolysis. The MM cells first need to home or migrate to the BM to receive necessary survival signals. In this work, we studied the role of CCR1 and CCR5, two known chemokine receptors, in both chemotaxis and osteolysis in the experimental 5TMM mouse model. A CCR1–specific (BX471) and a CCR5–specific (TAK779) antagonist were used to identify the function of both receptors. We could detect by RT-PCR and flow cytometric analyses the expression of both CCR1 and CCR5 on the cells and their major ligand, macrophage inflammatory protein 1α (MIP1α) could be detected by ELISA. In vitro migration assays showed that MIP1α induced a 2-fold increase in migration of 5TMM cells, which could only be blocked by TAK779. In vivo homing kinetics showed a 30% inhibition in BM homing when 5TMM cells were pre-treated with TAK779. We found, in vitro, that both inhibitors were able to reduce osteoclastogenesis and osteoclastic resorption. In vivo end-term treatment of 5T2MM mice with BX471 resulted in a reduction of the osteolytic lesions by 40%; while TAK779 treatment led to a 20% decrease in lesions. Furthermore, assessment of the microvessel density demonstrated a role for both receptors in MM induced angiogenesis. These data demonstrate the differential role of CCR1 and CCR5 in MM chemotaxis and MM associated osteolysis and angiogenesis.Research Grant Support: The work was financially supported by senior MMRF grants (K. Vanderkerken, P. Croucher), the Fonds voor Wetenschappelijk Onderzoek Vlaanderen (FWO-Vl), the Belgische Federatie tegen Kanker and the Onderzoeksraad Vrije Universiteit Brussel (OZR-VUB). K. Vanderkerken is a postdoctoral fellow of FWO-Vl. P. Croucher is supported by the Leukemia Research Fund and E. Menu by the van der Schueren award.     

Human lung dendritic cells have an immature phenotype with efficient mannose receptors.

Dendritic cells (DC) can be present at distinct stages of differentiation within the immune system. Sallusto and colleagues have recently described an in vitro culture system suitable for analyzing the maturation processes of DC (Sallusto and colleagues, J. Exp. Med. 1994;179:1109-1118). Monocytes cultured for 6 d in the presence of granulocyte macrophage colony-stimulating factor and interleukin-4 develop into immature DC with a high endocytic capacity but a low capacity to stimulate T cells. When challenged by lipopolysaccharide, these cells upregulate costimulatory molecules, express CD83, and become mature DC. CCR1 and CCR5 chemokine receptors are highly expressed on immature DC and downregulated on mature DC. This in vitro system was used to characterize human lung DC. Lung DC were shown to express some characteristics of in vitro immature DC. These are: (1) low expression of the costimulatory molecules CD40, CD80, and CD86; (2) poor expression of the differentiation marker CD83 and no CD1a; and (3) good capacity to incorporate dextran. Lung DC express moderate levels of CCR1 and CCR5. However, lung DC, like in vitro mature DC, express high levels of major histocompatibility complex Class II molecules, show low expression of CD14 and CD64, and are characterized by their high capacity to stimulate allogeneic T cells to proliferate during mixed leukocyte reactions (MLRs). Although lung DC express low levels of CD80 and CD86, the important role of these costimulatory molecules in inducing high MLR was demonstrated by using blocking antibodies. Therefore, while lung DC have overall a phenotype and an endocytic capacity close to in vitro immature DC, they share, like in vitro mature DC, a powerful capacity to stimulate T cells.     

转化生长因子β1抑制树突状细胞的成熟及下调TLR4的表达

目的：研究转化生长因子β1（TGF-β1）对小鼠来源树突状细胞（DC）功能的影响。 方法: 在培养体系中同时应用GM-CSF和TGF-β1培养的TGF β-DC，用脂多糖（LPS）观察其对外源刺激的反应，流式细胞仪（FCM）检测细胞表型，应用BrdU ELISA法通过96 h混合淋巴细胞反应（MLR）检测其同种异基因刺激能力，ELISA法测IL-12 p70的分泌水平，分别用半定量RT-PCR法和FCM检测Toll-like受体4（TLR4）表达。 结果: TGF β-DC与常规培养的未成熟DC（imDC）相比，CD80、CD86、I-Ab、CD40表达更低。LPS对TGF β-DC的促成熟作用反应不明显，其表面共刺激分子升高的幅度不大，异基因的刺激能力提高不显著，且IL-12 p70的分泌下降。RT-PCR与FCM都显示TGF β-DC较imDC弱表达TLR4。 结论: TGF β1能抑制DC共刺激分子的表达，TGF β-DC能抵抗LPS的促成熟作用，并可能与其TLR4表达下降有关。     

Induction of inhibitory antibodies to the CCR5 chemokine receptor and their complementary role in preventing SIV infection in macaques.

The seven-transmembrane G-protein-linked CCR5 molecule functions as a major coreceptor for HIV or simian immunodeficiency virus (SIV) infection. Antibodies to CCR5 were studied in rhesus macaques immunized with SIV grown in human CD4(+) T cells. These macaques were completely protected against i.v. challenge with live SIV. Sera from the protected macaques showed significantly greater inhibition of SIV replication (p < 0.001) and macrophage inflammatory protein-1beta-generated CCR5-dependent chemotaxis (p < 0.01) than sera from unprotected macaques, in the absence of significant neutralizing antibodies to SIV. These two functional assays demonstrate serum antibodies to the CCR5 receptors which were specifically inhibited by CCR5-transfected HEK-293 cells. We postulate that anti-CCR5 antibodies may be complementary to beta-chemokines in blocking CCR5 coreceptors to HIV or SIV binding and fusion of CD4(+) cells.