参考文献

Interleukin-10 (IL-10) has potent immunoregulatory effects on the maturation and the antigen-presenting cell (APC) function of dendritic cells (DCs). The molecular basis underlying these effects in DCs,however,is ill defined. It is well established that the transcription factor NF-kappaB is a key regulator of DC development,maturation,and APC function. This study was initiated to determine the effects of IL-10 on the NF-kappaB signaling pathway in immature DCs. IL-10 pretreatment of myeloid DCs cultured from bone marrow resulted in reduced DNA binding and nuclear translocation of NF-kappaB after anti-CD40 antibody or lipopolysaccharide (LPS) stimulation. Furthermore,inhibited NF-kappaB activation was characterized by reduced degradation,phosphorylation,or both of IkappaBalpha and IkappaBepsilon but not IkappaBbeta and by reduced phosphorylation of Ser536,located in the trans-activation domain of p65. Notably,IL-10-mediated inhibition of NF-kappaB coincided with suppressed IkappaB kinase (IKK) activity in vitro. Furthermore,IL-10 blocked inducible Akt phosphorylation,and inhibitors of phosphatidylinositol 3-kinase (PI3K) effectively suppressed the activation of Akt,IKK,and NF-kappaB. These findings demonstrate that IL-10 targets IKK activation in immature DCs and that suppressing the PI3K pathway in part mediates blockade of the pathway. View Publication

Obesity has been suggested to be a low-grade systemic inflammatory state,therefore we studied the interaction between human adipocytes and monocytes via adipose tissue (AT)-derived capillary endothelium. Cells composing the stroma-vascular fraction (SVF) of human ATs were characterized by fluorescence-activated cell sorter (FACS) analysis and two cell subsets (resident macrophages and endothelial cells [ECs]) were isolated using antibody-coupled microbeads. Media conditioned by mature adipocytes maintained in fibrin gels were applied to AT-derived ECs. Thereafter,the expression of endothelial adhesion molecules was analyzed as well as the adhesion and transmigration of human monocytes. FACS analysis showed that 11% of the SVF is composed of CD14(+)/CD31(+) cells,characterized as resident macrophages. A positive correlation was found between the BMI and the percentage of resident macrophages,suggesting that fat tissue growth is associated with a recruitment of blood monocytes. Incubation of AT-derived ECs with adipocyte-conditioned medium resulted in the upregulation of EC adhesion molecules and the increased chemotaxis of blood monocytes,an effect mimicked by recombinant human leptin. These results indicate that adipokines,such as leptin,activate ECs,leading to an enhanced diapedesis of blood monocytes,and suggesting that fat mass growth might be linked to inflammatory processes. View Publication

Prostanoids are arachidonic acid metabolites and are generally accepted to play pivotal functions in amongst others inflammation,platelet aggregation,and vasoconstriction/relaxation. Inhibition of their production with,for instance,aspirin has been used for over a century to combat a large variety of pathophysiological processes,with great clinical success. Hence,the cellular changes induced by prostanoids have been subject to an intensive research effort and especially prostanoid-dependent signal transduction has been extensively studied. In this review,we discuss the impact of the five basic prostanoids,TxA(2),PGF(2alpha),PGE(2),PGI(2),and PGD(2),via their receptors on cellular physiology. These inflammatory lipids may stimulate serpentine plasma membrane-localized receptors,which in turn affect major signaling pathways,such as the MAP kinase pathway and the protein kinase A pathway,finally resulting in altered cellular physiology. In addition,prostanoids may activate the PPARgamma members of the steroid/thyroid family of nuclear hormone receptors,which act as transcription factors and may thus directly influence gene transcription. Finally,evidence exists that prostanoids act as second messengers downstream of mitogen receptor activation,mediating events,such as cytoskeletal changes,maybe via direct interaction with GTPase activating proteins. The final cellular reaction to prostaglandin stimulation will most likely depend on combined effects of the above-mentioned levels of interaction between prostaglandins and their cellular receptors. View Publication

Angiotensin I-converting enzyme (ACE) inhibitors can affect hematopoiesis by several mechanisms including inhibition of angiotensin II formation and increasing plasma concentrations of AcSDKP (acetyl-N-Ser-Asp-Lys-Pro),an ACE substrate and a negative regulator of hematopoiesis. We tested whether ACE inhibition could decrease the hematopoietic toxicity of lethal or sublethal irradiation protocols. In all cases,short treatment with the ACE inhibitor perindopril protected against irradiation-induced death. ACE inhibition accelerated hematopoietic recovery and led to a significant increase in platelet and red cell counts. Pretreatment with perindopril increased bone marrow cellularity and the number of hematopoietic progenitors (granulocyte macrophage colony-forming unit [CFU-GM],erythroid burst-forming unit [BFU-E],and megakaryocyte colony-forming unit [CFU-MK]) from day 7 to 28 after irradiation. Perindopril also increased the number of hematopoietic stem cells with at least a short-term reconstitutive activity in animals that recovered from irradiation. To determine the mechanism of action involved,we evaluated the effects of increasing AcSDKP plasma concentrations and of an angiotensin II type 1 (AT1) receptor antagonist (telmisartan) on radioprotection. We found that the AT1-receptor antagonism mediated similar radioprotection as the ACE inhibitor. These results suggest that ACE inhibitors and AT1-receptor antagonists could be used to decrease the hematopoietic toxicity of irradiation. View Publication

Hematopoietic stem cells (HSCs) are a subset of bone marrow cells that are capable of self-renewal and of giving rise to all types of blood cells. However,the mechanisms involved in controlling the number and abilities of HSCs remain largely unknown. The Indian hedgehog (Ihh) signal has an essential role in inducing hematopoietic tissue during embryogenesis. We investigated the roles of the Ihh in coculture with CD34+ cells and human stromal cells. Ihh mRNA was expressed in primary and telomerized human (hTERT) stromal cells,and its receptor molecules were detected in CD34+ cells. Ihh gene transfer into hTERT stromal cells enhanced their hematopoietic supporting potential,which was elevated compared with control stromal cells,as indicated by the colony-forming units in culture (CFU-Cs) (26-fold +/- 2-fold versus 59-fold +/- 3-fold of the initial cell number; mixed colony-forming units [CFU-Mix's],63-fold +/- 37-fold versus 349-fold +/- 116-fold). Engraftments of nonobese diabetic/severe combined immunodeficiency-beta2m-/- (NOD/SCID-beta2-/-) repopulating cells (RCs) expanded on Ihh stromal cells were significantly higher compared with control coculture results,and engraftment was neutralized by addition of an antihedgehog antibody. Limiting dilution analysis indicated that NOD/SCID-beta2m-/- RCs proliferated efficiently on Ihh stromal cells,compared with control stromal cells. These results indicate that Ihh gene transfer could enhance the primitive hematopoietic support ability of human stromal cells. View Publication

Chromosomal rearrangements of the 11p15 locus have been identified in hematopoietic malignancies,resulting in translocations involving the N-terminal portion of the nucleoporin gene NUP98. Fifteen different fusion partner genes have been identified for NUP98,and more than one half of these are homeobox transcription factors. By contrast,the NUP98 fusion partner in t(11;20) is Topoisomerase I (TOP1),a catalytic enzyme recognized for its key role in relaxing supercoiled DNA. We now show that retrovirally engineered expression of NUP98-TOP1 in murine bone marrow confers a potent in vitro growth advantage and a block in differentiation in hematopoietic precursors,evidenced by a competitive growth advantage in liquid culture,increased replating efficient of colony-forming cells (CFCs),and a marked increase in spleen colony-forming cell output. Moreover,in a murine bone marrow transplantation model,NUP98-TOP1 expression led to a lethal,transplantable leukemia characterized by extremely high white cell counts,splenomegaly,and mild anemia. Strikingly,a mutation to a TOP1 site to inactivate the isomerase activity essentially left unaltered the growth-promoting and leukemogenic effects of NUP98-TOP1. These findings,together with similar biologic effects reported for NUP98-HOX fusions,suggest unexpected,overlapping functions of NUP98 fusion genes,perhaps related to common DNA binding properties. View Publication

From July 1995 to December 2001,42 patients with leukemia aged 1-42 years underwent cord blood transplant (CBT) from unrelated,textless or = 2 antigen HLA mismatched donors. In all,26 patients were in textless or = 2nd complete remission and 16 in more advanced phase. Conditioning regimens,graft-versus-host disease (GVHD) prophylaxis and supportive policy were uniform for all patients. The cumulative incidence of engraftment was 90% (95% CI: 0.78-0.91). The cumulative incidence of III-IV grade acute- and chronic-GVHD was 9% (95% CI: 0.04-0.24) and 35% (95% CI: 0.21-0.60),respectively. The 4-year cumulative incidence of transplant-related mortality (TRM) and relapse was 28% (95% CI: 0.17-0.47) and 25% (95% CI: 0.14-0.45),respectively. The 4-year overall survival (OS),leukemia-free survival (LFS) and event-free survival (EFS) were 45% (95% CI: 0.27-0.63),47% (95% CI: 0.30-0.64) and 46% (95% CI: 0.30-0.62),respectively. In multivariate analysis,the most important factor affecting outcomes was the CFU-GM dose,associated with CMV serology (P=0.003 and 0.04,respectively) in influencing OS and with patient sex (P=0.008 and 0.03,respectively) in influencing LFS. Finally,CFU-GM dose was the only factor that affected EFS significantly (P=0.02). In conclusion,the infused cell dose expressed as in vitro progenitor cell growth is highly predictive of outcomes after an unrelated CBT and should be considered the main parameter in selecting cord blood units for transplant. View Publication

The future use of adult mesenchymal stem cells (MSCs) for human therapies depends on the establishment of preclinical studies with other mammals such as mouse. Surprisingly,purification and characterisation of murine MSCs were only poorly documented. The aim of this study was to purify mouse MSCs from adult bone marrow and to functionally characterise their abilities to differentiate along diverse lineages. Adherent cells from adult C57Bl/6J mouse bone marrow were depleted of granulo-monocytic cells and subsequently allowed to grow on fibronectin-coated dishes in presence of fetal bovine serum and growth factors. The growing fibroblastoid cell population primarily consisted of spindle- and star-shaped cells with significant renewal capacity as they were cultured until 30 passages (about 60 doubling population). We fully demonstrated the MSC phenotype of these cells by inducing them to differentiate along osteoblastic,adipocytic,and chondrocytic pathways. Mouse MSCs (mMSCs) sharing the same morphological and functional characteristics as human MSCs can be successfully isolated from adult bone marrow without previous mouse or bone marrow treatment. Therefore,mMSCs will be an important tool to study the in vivo behaviour and fate of this cell type after grafting in mouse pathology models. View Publication

The cellular reservoir for latent human cytomegalovirus (HCMV) in the hematopoietic compartment,and the mechanisms governing a latent infection and reactivation from latency are unknown. Previous work has demonstrated that HCMV infects CD34+ progenitors and expresses a limited subset of viral genes. The outcome of HCMV infection may depend on the cell subpopulations infected within the heterogeneous CD34+ compartment. We compared HCMV infection in well-defined CD34+ cell subpopulations. HCMV infection inhibited hematopoietic colony formation from CD34+/CD38- but not CD34+/c-kit+ cells. CD34+/CD38- cells transiently expressed a large subset of HCMV genes that were not expressed in CD34+/c-kit+ cells or cells expressing more mature cell surface phenotypes. Although viral genomes were present in infected cells,viral gene expression was undetectable by 10 days after infection. Importantly,viral replication could be reactivated by coculture with permissive fibroblasts only from the CD34+/CD38- population. Strikingly,a subpopulation of CD34+/CD38- cells expressing a stem cell phenotype (lineage-/Thy-1+) supported a productive HCMV infection. These studies demonstrate that the outcome of HCMV infection in the hematopoietic compartment is dependent on the nature of the cell subpopulations infected and that CD34+/CD38- cells support an HCMV infection with the hallmarks of latency. View Publication

The fate of pluripotent stem cells is tightly controlled during early embryonic development. Both the derivation and the maintenance of embryonic stem cells (ES cells) in vitro depend on feeder cell-derived growth factors that are largely unidentified. To dissect the mechanisms governing pluripotency,we conducted a screen to identify factors that are produced by mouse embryonic fibroblast STO cells and are required to maintain the pluripotency of ES cells. One of the factors is bone morphogenetic protein 4 (BMP4). Unexpectedly,the major effect of BMP4 on the self-renewal of ES cells is accomplished by means of the inhibition of both extracellular receptor kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) pathways,and inhibitors of ERK and p38 MAPKs mimic the effect of BMP4 on ES cells. Importantly,inhibition of the p38 MAPK pathway by SB203580 overcomes the block in deriving ES cells from blastocysts lacking a functional Alk3,the BMP type IA receptor. These results uncover a paradigm for BMP signaling in the biology of pluripotent stem cells. View Publication