Transcriptional profiling identifies genes induced by hepatocyte-derived extracellular matrix in metastatic human colorectal cancer cell lines

The milieu of the liver, and in particular hepatocyte-derived extracellular matrix (hECM), is a critical factor regulating development of liver metastases of colorectal cancer (CRC) cells. The present study has investigated genes altered by hECM in CRC cells and particularly by heparan sulfate chains of hepatocyte proteoglycans. Gene profiling analysis shows that after 2 days on hECM, 226 genes are up-regulated more than 2-fold in strongly metastatic SM cells, including genes involved in growth arrest and apoptosis, signal transduction, cell migration, proliferation, communication and angiogenesis, with activation of the erbB signaling network and p53 effectors. Genes down-regulated by hECM include genes involved in lipogenesis and the S phase of the cell cycle. Further studies exploring the kinetics of gene expression after 4 and 7 days culture on hECM show induction of EGF family members and of stem cell markers. In particular, hECM, but not collagen, increases mRNA expression of HB-EGF and colon stem cell marker leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5). Expression of these genes is not induced by hECM depleted of the heparan sulfate chains of proteoglycans. Lastly, a specific cell population positive for cancer stem cell (CSC) markers LGR5, epCAM and CD133, but negative for CD44, appears after 7 days culture on hECM, a population which is reduced by 50 % in cells grown on heparan sulfated-depleted hECM. Collectively, the data suggest that hECM induces growth factors and receptors regulating proliferation of metastatic CRC in the liver and offers a growth advantage for specific populations expressing CSC markers.     

Systemic bacterial infections affect dendritic cell development and function

Dendritic cells (DCs) are critical in host defense against infection. DC depletion is an early event in the course of sepsis that may impair the host defense mechanisms. Here, we addressed whether DC depletion and dysfunction are pathogen-independent, mediated via pattern recognition receptors, and are due to impaired DC development upon systemic infection with the Gram-negative bacterium Escherichia coli and the Gram-positive pathogen Staphylococcus aureus.Infection with E. coli and S. aureus led to reduced numbers of splenic DC subsets and of DC progenitors in the bone marrow (BM) with this effect persisting significantly longer in mice infected with S. aureus than with E. coli. The reduction of DC subsets and their progenitors was mainly TLR-independent as was the infection-induced monopoiesis. Moreover, de novo DC development was impaired in mice infected with S. aureus, and BM cells from E. coli or S. aureus infected mice favored macrophage differentiation in vitro. As a consequence of reduced DC numbers and their reduced expression of MHC II less CD4⁺ and CD8⁺ T cells, especially Th1 and IFN-γ producing CD8⁺ T cells, could be detected in S. aureus compared to E. coli infected mice. These differences are reflected in the rapid killing of E. coli as opposed to an increase in bacterial load in S. aureus.In summary, our study supports the idea that systemic bacterial infections generally affect the number and development of DCs and thereby the T cell responses, but the magnitude is pathogen-dependent.     

Protease-activated receptor-2 signaling triggers dendritic cell development

Dendritic cells (DC) are potent antigen-presenting cells that govern the effector cell responses of the immune system. DC are thought to continuously develop from circulating progenitors in a process that is accelerated by inflammatory stimuli. However, the physiological signals that regulate the development of DC from precursor cells have not been well defined. Here we show that a serine protease acting via protease-activated receptor-2 (PAR-2) stimulates the development of DC from bone marrow progenitor cells cultured in granulocyte-macrophage colony-stimulating factor and IL-4. DC fail to develop in bone marrow cultures treated with soy bean trypsin inhibitor, a serine protease inhibitor, but this inhibition is overcome by a PAR-2 agonist peptide. DC do not spontaneously develop from the bone marrow of PAR-2-deficient mice, but can be stimulated to do so by inflammatory mediators. These results suggest that endogenous serine proteases stimulate DC development in vitro. Thus, serine proteases may help trigger adaptive immune responses in vivo.     

Understanding human dendritic cell biology through gene profiling

Dendritic cells are potent antigen presenting cells whose function has been associated with a variety of immunological disorders. Because of their relevance to human disease, extensive efforts have been made to gain a better understanding of their biology. One aspect of these efforts has been in the identification of pertinent molecules expressed in these cells through gene profiling experiments and proteomics. In this review, we summarize the results from the various profiling studies that have been done with human dendritic cells. We focus on molecules, which have been confirmed by other methods, such as quantitative PCR, or have been identified in multiple profiling studies to be expressed in the respective dendritic cell type. Through such profiling experiments and subsequent analysis, interesting molecules have been identified which can be further studied to determine their role in dendritic cell biology.Received 25 February 2004; accepted by A. Falus 14 April 2004     

Mechanisms of dendritic cell function

There is now considerable evidence, from in vivo and in vitro studies, supporting the claim that dendritic cells are the principal accessory cells of the vertebrate immune system. Until recently, however, the biology of the dendritic cell accessory mechanism has remained obscure. Here, Philip King and David Katz review recent findings that have clarified several aspects of this mechanism, providing a possible basis for the potent T-cell stimulating capacity of the dendritic cell, and yielding clues to the ontogenetic relationships of these cells and to their role in immunopathology.     

食管鳞状细胞癌组织中Id1和Id2的表达及其意义

目的研究Id1、Id2在食管鳞状细胞癌中的表达及其意义。方法采用免疫组织化学SP法和图像分析技术检测122例食管鳞状细胞癌及90例癌旁正常组织中Id1、Id2的表达情况。结果122例食管鳞状细胞癌中Id1、Id2表达高于癌旁正常组织(P0.01);Id1、Id2表达强度与患者的性别、年龄、淋巴结转移未见明显相关性(P0.05);Id1表达高分化与低分化组差异有显著性(P0.05);Id2的表达与肿瘤的分化程度成负相关(P0.05),且与肿瘤浸润深度正相关(P0.05)。结论Id1、Id2的高表达可能是食管鳞状细胞癌一个重要的分子学改变,Id2可作为判断食管鳞状细胞癌生物学行为的潜在指标。     

CD40 and dendritic cell function

CD40 has emerged as a key signaling pathway for the function of B cells, monocytes, and dendritic cells (DC) in the immune system, and plays a major role in inflammatory pathways of nonhemopoietic cells. CD40 is expressed by monocytes and DC and is up-regulated when DC migrate from the periphery to draining lymph nodes (DLN) in response to microbial challenge. CD154 signaling by MHC-restricted, activated CD4+ T cells induces differentiation of DC, as defined by an increased surface expression of MHC, costimulatory, and adhesion molecules. Thus, CD40 functions in the adaptive immune response as a trigger for the expression of costimulatory molecules for efficient T-cell activation. CD40 ligation of DC also has the capacity to induce high levels of the cytokine IL-12, which polarizes CD4+ T cells toward a T helper 1 (Th1) type, enhances proliferation of CD8+ T cells, and activates NK cells. CD40 may also play an important role in the decision between tolerance and immunity and the generation of regulatory CD4+ T cells that are thought to maintain peripheral self-tolerance in vivo.