CXCL12 (SDF-1), a CXC-chemokine, and its specific receptor, CXCR4, have recently been shown to be involved in tumourgenesis, proliferation and angiogenesis. Therefore, we analysed CXCL12α/CXCR4 expression and function in four human kidney cancer cell lines (A-498, CAKI-1, CAKI-2, HA-7), 10 freshly harvested human tumour samples and corresponding normal kidney tissue. While none of the analysed tumour cell lines expressed CXCL12α, A-498 cells were found to express CXCR4. More importantly, real-time RT–PCR analysis of 10 tumour samples and respective adjacent normal kidney tissue disclosed a distinct and divergent downregulation of CXCL12α and upregulation of CXCR4 in primary tumour tissue. To prove that the CXCR4 protein is functionally active, rhCXCL12α was investigated for its ability to induce changes of intracellular calcium levels in A-498 cells. Moreover, we used cDNA expression arrays to evaluate the biological influence of CXCL12α. Comparing gene expression profiles in rhCXCL12α stimulated vs unstimulated A-498 kidney cancer cells revealed specific regulation of 31 out of 1176 genes tested on a selected human cancer array, with a prominent stimulation of genes involved in cell-cycle regulation and apoptosis. The genetic changes reported here should provide new insights into the developmental paths leading to tumour progression and may also aid the design of new approaches to therapeutic intervention. British Journal of Cancer (2002) 86 , 1250–1256. DOI: 10.1038/sj/bjc/6600221 www.bjcancer.com © 2002 Cancer Research UK

Salmonella Typhimurium causes diarrhea by infecting the epithelium and lamina propria of the intestinal mucosa and by secreting various effector proteins through type III secretion systems (TTSSs). However, the mechanisms by which Salmonella transverses the epithelium and is subsequently released into the lamina propria are poorly understood. Using a murine Salmonella-diarrhea model and in vivo microscopy, we show that epithelial traversal requires TTSS-1-mediated invasion and TTSS-2-dependent trafficking to the basolateral side. After being released into the lamina propria, the bacterium is transiently extracellular before being taken up by phagocytes, including CD11c(+)CX(3)CR1(high) monocytic phagocytes (MPs), which were found to constitutively sample cellular material shed from the basolateral side of the epithelium. Thus, Salmonella infects the cecal mucsa through a step-wise process wherein the bacterium transverses the epithelium through TTSS-2-dependent trafficking and then likely exploits lamina propria MPs, which are sampling the epithelium, to enter and replicate within the host.

IntroductionFor activation, T cells must physically engage antigen-presenting cells (APCs). 1 With B cells as APCs, the interaction plane, termed "immunologic synapse," 2 is a highly organized structure of signaling and adhesion molecules. 3 A mature synapse requires at least 30 minutes of stable cell-cell interaction to form 2 and can last for several hours in vitro 4 and in explanted lymph nodes. 5 Although investigated mostly with B cells or surrogate APCs in liquid cultures, the concept of long-term contacts has previously been considered a universal feature of all cognate T cell-APC (T-APC) interactions. 6 However, in promigratory collagen matrices as environment for T-APC interaction also dynamic and short-lived encounters to dendritic cells (DCs) are able to induce the full spectrum of T-cell signaling and activation. 7 Here, T cells engage DCs only for a few minutes, detach, and establish new contacts to neighboring DCs until activation is achieved. 8 Migrating T cells can drag a mature synapse over the surface of an APC, showing the principal compatibility of T-cell migration and synapse maintenance. 9 Furthermore, studies on APC-T interactions in explanted lymph nodes 10 or thymic organ cultures 11 have observed both static and dynamic interactions between T cells or thymocytes and local APCs. Intravital imaging revealed a 3-phase model of T-APC interaction in a lymph node, in which CD8 T cells displayed a period of 8 hours, characterized by short-lived and dynamic DC scanning, followed by 12 hours with stable interactions to single DCs and a return to high motility afterward. 12 During adhesive contacts, T cells maintained considerable cytoskeletal activity and shape change. 12 Weaver's group (Hurez et al 13 and Saparov et al 14 ) described a heterogeneity in naive T cells, leading to a majority of short-interacting cells, which could proliferate but did not produce interleukin 2 (IL-2), the latter only being produced by T cells making long contacts to APCs. T-cell receptor (TCR)-proximal signals such as phosphorylation of zeta-associated protein 70 (ZAP-70) or Lck 15 are only detectable for the first 15 minutes after the onset of a contact and are already absent before a synapse has fully matured. 16 In contrast, active phosphatidyl inositol 3 (PI3)-kinase is located in an initial segment (IS) over the entire period of T-APC interaction and interference with this process inhibits T-cell activation. 17,18 However, besides a continuous TCR signal, also discontinuous signaling can lead to T-cell activation and effector function. 19 Together, these observations suggest that a spectrum of interaction modes, reaching from static adhesion and clustering to dynamic migratory encounters with APCs, can lead to the activation of T cells. 8,20 So far no systematic analysis on the biophysical and molecular principles underlying static versus dynamic interactions has been performed. According to one hypothesis, the nature of the APC, which is encountered by the T cell, is decisive for the mode of interaction, 8 wh...

Enterohemorrhagic Escherichia coli (EHEC) is the major cause of hemolyticuremic syndrome (HUS) characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. EHEC produces one or more Shiga toxins (Stx1 and Stx2), and it was assumed that Stx's only relevant biologic activity was cell destruction through inhibition of protein synthesis. However, recent data indicate that in vivo the cytokine milieu may determine whether endothelial cells survive or undergo apoptosis/necrosis when exposed to Stxs. In this study, we analyzed the genome-wide expression patterns of human endothelial cells stimulated with subinhibitory concentrations of Stxs in order to characterize the genomic expression program involved in the vascular pathology of HUS. We found that Stxs elicited few, but reproducible, changes in gene expression. The majority of genes reported in this study encodes for chemokines and cytokines, which might contribute to the multifaceted inflammatory response of host endothelial cells observed in patients suffering from EHEC disease. In addition, our data provide for the first time molecular insights into the epidemiologically well-established higher pathogenicity of Stx2 over Stx1. (Blood. 2003;102: 1323-1332

Here, we report the identification of the ubiquitin-like gene UBD as a downstream element of FOXP3 in human activated regulatory CD4 þ CD25 hi T cells (T reg ). Retroviral transduction of UBD in human allo-reactive effector CD4 þ T helper (T h ) cells upregulates CD25 and mediates downregulation of IL4 and IL5 expression similar to overexpression of FOXP3. Moreover, UBD impairs T h cell proliferation without upregulation of FOXP3 and impairs calcium mobilization. In the presence of ionomycin, overexpression of UBD in T h cells leads to the induction of IL1R2 that resemble FOXP3-transduced T h cells and naturally derived T reg cells. A comparison of the transcriptome of FOXP3-and UBD-transduced T h cells with T reg cells allowed the identification of the gene LGALS3. However, high levels of LGALS3 protein expression were observed only in human CD4 þ CD25 hi derived T reg cells and FOXP3-transduced T h cells, whereas little was induced in UBD-transduced T h cells. Thus, UBD contributes to the anergic phenotype of human regulatory T cells and acts downstream in FOXP3 induced regulatory signaling pathways, including regulation of LGALS3 expression. High levels of LGALS3 expression represent a FOXP3-signature of human antigen-stimulated CD4 þ CD25 hi derived regulatory T cells.

MSCs derived from the umbilical cord tissue, termed UCX, were investigated for their immunomodulatory properties and compared to bone marrow-derived MSCs (BM-MSCs), the gold-standard in immunotherapy. Immunogenicity and immunosuppression were assessed by mixed lymphocyte reactions, suppression of lymphocyte proliferation and induction of regulatory T cells. Results showed that UCX were less immunogenic and showed higher immunosuppression activity than BM-MSCs. Further, UCX did not need prior activation or priming to exert their immunomodulatory effects. This was further corroborated in vivo in a model of acute inflammation. To elucidate the potency differences observed between UCX and BM-MSCs, gene expression related to immune modulation was analysed in both cell types. Several gene expression profile differences were found between UCX and BM-MSCs, namely decreased expression of HLA-DRA, HO-1, IGFBP1, 4 and 6, ILR1, IL6R and PTGES and increased expression of CD200, CD273, CD274, IL1B, IL-8, LIF and TGFB2. The latter were confirmed at the protein expression level. Overall, these results show that UCX seem to be naturally more potent immunosuppressors and less immunogenic than BM-MSCs. We propose that these differences may be due to increased levels of immunomodulatory surface proteins such as CD200, CD273, CD274 and cytokines such as IL1β, IL-8, LIF and TGFβ2.

No abstract

Up-regulation of receptor-ligand pairs during interaction of an MHC-presented epitope on dendritic cells (DCs) with cognate TCR may amplify, sustain, and drive diversity in the ensuing T cell immune response. Members of the TNF ligand superfamily and the TNFR superfamily contribute to this costimulatory molecule signaling. In this study, we used replication deficient adenoviruses to introduce a model tumor-associated Ag (the E7 oncoprotein of human papillomavirus 16) and the T cell costimulatory molecule 4-1BBL into murine DCs, and monitored the ability of these recombinant DCs to elicit E7-directed T cell responses following immunization. Splenocytes from mice immunized with DCs expressing E7 alone elicited E7-directed effector and memory CTL responses. Coexpression of 4-1BBL in these E7-expressing DCs increased effector and memory CTL responses when they were used for immunization. 4-1BBL expression up-regulated CD80 and CD86 second signaling molecules in DCs. We also report an additive effect of 4-1BBL and receptor activator of NF-κB/receptor activator of NF-κB ligand coexpression in E7-transduced DC immunogens on E7-directed effector and memory CTL responses and on MHC class II and CD80/86 expression in DCs. Additionally, expression of 4-1BBL in E7-transduced DCs reduced nonspecific T cell activation characteristic of adenovirus vector-associated immunization. The results have generic implications for improved or tumor Ag-expressing DC vaccines by incorporation of exogenous 4-1BBL. There are also specific implications for an improved DC-based vaccine for human papillomavirus 16-associated cervical carcinoma.