Distribution and kinetics of SR-PSOX/CXCL16 and CXCR6 expression on human dendritic cell subsets and CD4+ T cells

Dendritic cells (DCs) coordinate T cell responses by producing T cell-attracting chemokines and by inducing the expression of chemokine receptors on T cells. Scavenger receptor for phosphatidylserine and oxidized lipoprotein (SR-PSOX)/CXC chemokine ligand 16 (CXCL16) is a unique chemokine that also functions as an endocytic receptor and an adhesion molecule in its membrane-bound form. SR-PSOX/CXCL16 is the only known ligand of CXC chemokine receptor 6 (CXCR6) that is expressed on activated T cells and thus, may play an important role in enhancing effector functions of T cells. Here, we investigated the expression of SR-PSOX/CXCL16 on human DC subsets and that of CXCR6 on T cell subpopulations to elucidate the dynamics of CXCL16/CXCR6 interaction in DC/T cell responses. Membrane-bound SR-PSOX/CXCL16 was expressed on macrophages, monocyte-derived DCs, and blood myeloid DCs, and the expression increased after DC maturation. Myeloid antigen-presenting cells constitutively secreted SR-PSOX/CXCL16 for an extended period, suggesting the involvement of CXCL16 in peripheral and lymphoid tissues. Plasmacytoid DCs hardly expressed SR-PSOX/CXCL16 on their surfaces but secreted significant amounts of SR-PSOX/CXCL16. A subset of CD4+ effector memory T (T(EM)) cells constitutively expressed CXCR6, whereas central memory T cells (T(CM)) and naive T cells did not. Upon stimulation with mature DCs, however, the expression of CXCR6 on T(CM) cells was markedly up-regulated, whereas the expression on naive T cells was induced only weakly. These results suggest that the interaction between SR-PSOX/CXCL16 and CXCR6 plays an important role in enhancing T(CM) cell responses by mature DCs in lymphoid tissues and in augmenting T(EM) cell responses by macrophages in peripheral inflamed tissues.     

CXCL16 is a novel mediator of the innate immunity of epidermal keratinocytes

The epidermis is constantly exposed to a variety of microbial pathogens and plays a vital role in resisting them. Soluble CXC chemokine ligand (CXCL) 16, which is one of the ELR- CXC chemokines, acts as a mediator of innate immunity by attracting CXC chemokine receptor (CXCR) 6-expressing cells, such as activated T cells and NKT cells. However, the production of CXCL16 by non-immune cells remains unclear. We found that cultured keratinocytes produced a significant amount of CXCL16 (2-3 ng per 10(6) cells per 24 h). Stimulation with tumor necrosis factor alpha, IL-1alpha, IFN-gamma, peptidoglycan and polyinosinic-polycytidylic acid [poly(I:C)] enhanced CXCL16 production. The forms of CXCL16 in the culture supernatants had molecular weights of 14, 28 and 50 kDa. Immunohistochemical analysis revealed that the normal human epidermis expressed CXCL16. As several chemokines have anti-microbial activities, we studied the anti-microbial activity of CXCL16. The chemokine domain of CXCL16 at concentrations >5 microg ml(-1) had significant anti-microbial activity against Staphylococcus aureus and Escherichia coli. Killing activity was retained at the physiological salt concentration in the presence of carbonate. In conclusion, CXCL16 is a novel mediator of the innate immune reactivities of epidermal keratinocytes.     

The expression of the chemokine receptor CXCR3 and its ligand, CXCL10, in human breast adenocarcinoma cell lines

The acquisition of a metastatic phenotype in breast epithelial cells is a progressive process, influenced by a large variety of cellular and soluble factors. Of these, members of the chemokine superfamily, such as CCL2, CCL5, CXCL8 and CXCL12 have been recently suggested to promote breast cancer progression. A pre-requisite for elucidation of the role of other chemokines in breast cancer progression is the characterization of chemokine and chemokine receptor expression by breast tumor cells. The present study focuses on CXCL10, a CXC chemokine that was recently suggested to have anti-malignant properties, and its corresponding receptor CXCR3. CXCR3 expression was detected in three human breast adenocarcinoma cell lines, MDA-MB-231, MCF-7 and T47D. CXCR3 expression was potently up-regulated by growing the cells under stress conditions, imposed by serum starvation. Unlike many other chemokine receptors, CXCR3 expression was not down-regulated by exposure to high concentrations (500ng/ml) of its ligand, CXCL10, but rather was promoted. CXCL10-induced up-regulation of CXCR3 expression in the three cell lines was inhibited by cycloheximide, indicating that de novo protein synthesis is required for this process. In addition to CXCR3, the secretion of CXCL10 was noted in the MDA-MB-231, MCF-7 and T47D cells. CXCL10 secretion was found to be down-regulated by IL-6, a potentially pro-malignant cytokine in breast cancer. The concomitant expression of CXCR3 and CXCL10 in breast tumor cells suggests that a CXCR3-CXCL10 axis may function in these cells, and paves the way for an in depth analysis of CXCL10-CXCR3 interactions in breast tumor cells.     

Infiltrating CD8+ T cells in oral lichen planus predominantly express CCR5 and CXCR3 and carry respective chemokine ligands RANTES/CCL5 and IP-10/CXCL10 in their cytolytic granules: a potential self-recruiting mechanism

Lichen planus is a chronic inflammatory disease of the skin and oral mucosa in which the cell-mediated cytotoxicity is regarded as a major mechanism of pathogenesis. To understand its pathophysiology further, the present study examined the in situ expression of chemokines and chemokine receptors in oral lichen planus. Immunohistochemical analysis of 15 cases has consistently revealed that infiltrating CD4(+) and CD8(+) T cells in the submucosa predominantly expressed CCR5 and CXCR3. Furthermore, infiltrating T cells, particularly CD8(+) T cells, were positive for RANTES/CCL5 and IP-10/CXCL10, the ligands of CCR5 and CXCR3, respectively. By immunoelectron microscopy, these chemokines were localized in the cytolytic granules of CD8(+) T cells. Lesional keratinocytes also overexpressed the ligands of CXCR3, namely, MIG/CXCL9, CXCL10, and I-TAC/CXCL11. Our data suggest that the chemokines signaling via CCR5 and CXCR3, which are known to be selectively expressed by type 1 T cells, are predominantly involved in T-cell infiltration of oral lichen planus. Furthermore, the presence of CCL5 and CXCL10 in the cytolytic granules of tissue-infiltrating CD8(+) T cells expressing CCR5 and CXCR3 reveals a potential self-recruiting mechanism involving activated effector cytotoxic T cells.     

I-TAC/CXCL11 is a natural antagonist for CCR5

The selective CXC chemokine receptor 3 (CXCR3) agonists, monokine induced by interferon-gamma (IFN- gamma)/CXC chemokine ligand 9 (CXCL9), IFN-inducible protein 10/CXCL10, and IFN-inducible T cell alpha chemoattractant (I-TAC)/CXCL11, attract CXCR3+ cells such as CD45RO+ T lymphocytes, B cells, and natural killer cells. Further, all three chemokines are potent, natural antagonists for chemokine receptor 3 (CCR3) and feature defensin-like, antimicrobial activities. In this study, we show that I-TAC, in addition to these effects, acts as an antagonist for CCR5. I-TAC inhibited the binding of macrophage-inflammatory protein-1alpha (MIP-1alpha)/CC chemokine ligand 3 (CCL3) to cells transfected with CCR5 and to monocytes. Furthermore, cell migration evoked by regulated on activation, normal T expressed and secreted (RANTES)/CCL5 and MIP-1beta/CCL4, the selective agonist of CCR5, was inhibited in transfected cells and monocytes, respectively. In two other functional assays, namely the release of free intracellular calcium and actin polymerization, I-TAC reduced CCR5 activities to minimal levels. Sequence and structure analyses indicate a potential role for K17, K49, and Q51 of I-TAC in CCR5 binding. Our results expand on the potential role of I-TAC as a negative modulator in leukocyte migration and activation, as I-TAC would specifically counteract the responses mediated by many "classical," inflammatory chemokines that act not only via CCR3 but via CCR5 as well.     

CXCL12 and CXCR4 expression by human gingival fibroblasts in periodontal disease

CXCL12 is a CXC chemokine that is related to lymphocyte infiltration and angiogenesis in inflammatory sites such as arthritis. However, the expression and roles of CXCL12 in periodontal disease are uncertain. The aim of this study was to assess the expression of CXCL12 and its receptor, CXCR4, in periodontal tissue and to investigate the properties of CXCL12 and CXCR4 expression by human gingival fibroblasts (HGF). RT-PCR analysis revealed that CXCL12 and CXCR4 mRNA were expressed in both normal gingival tissues and periodontal diseased tissues. Immunohistochemistry disclosed that CXCL12 was expressed and CXCR4 positive cells were found in both normal and periodontal diseased gingival tissues. Our in vitro experiments elucidated that HGF constitutively produced CXCL12, and the levels were enhanced by stimulation with tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), transforming growth factor-beta (TGF-beta), regulated upon activation normal T cell expressed and secreted (RANTES) and macrophage inflammatory protein 3(alpha) (MIP-3(alpha)). On the other hand, heat killed Porphyromonas gingivalis (P. gingivalis) and P. gingivalis LPS reduced the CXCL12 production by HGF. Flow cytometry analysis clarified that CXCR4 was highly expressed on HGF, and CXCR4 expression was abrogated by TNF-alpha, IFN-gamma and P. gingivalis LPS. Moreover, CXCL12 induced vascular endothelial growth factor (VEGF) production by HGF. Our results demonstrated that CXCL12 might be related to CXCR4+ cells infiltration and angiogenesis both in normal periodontal tissues and periodontal diseased tissue. P. gingivalis, a known periodontal pathogen, inhibits the production of CXCL12 and the expression of CXCR4 by HGF. This fact means that P. gingivalis may inhibit CXCR4+ cells infiltration and neovascularization in periodontal tissue and escape from the immune response.     

TLR ligands and cytokines induce CXCR3 ligands in endothelial cells: enhanced CXCL9 in autoimmune arthritis

CXC chemokines are potent attractants of neutrophil granulocytes, T cells or natural killer cells. Toll-like receptors (TLR) recognize microbial components and are also activated by endogenous molecules possibly implicated in autoimmune arthritis. In contrast to CXC chemokine ligand 8 (CXCL8), no CXC chemokine receptor 3 (CXCR3) ligand (ie CXCL9, CXCL10 and CXCL11) was induced by bacterial TLR ligands in human microvascular endothelial cells (HMVEC). However, peptidoglycan (PGN), double-stranded (ds) RNA or lipopolysaccharide (LPS) (TLR2, TLR3 or TLR4 ligands, respectively) synergized with interferon-gamma (IFN-gamma) at inducing CXCL9 and CXCL10. In contrast, enhanced CXCL11 secretion was only obtained when IFN-gamma was combined with TLR3 ligand. Furthermore, flagellin, loxoribine and unmethylated CpG oligonucleotide (TLR5, TLR7 and TLR9 ligands, respectively) did not enhance IFN-gamma-dependent CXCR3 ligand production in HMVEC. In analogy with TLR ligands, tumor necrosis factor-alpha (TNF-alpha) or interleukin-1beta (IL-1beta), in combination with IFN-gamma, synergistically induced CXCL9 and CXCL11 in HMVEC and human fibroblasts, two fundamental cell types delineating the joint cavity. Etanercept, a humanized soluble recombinant p75 TNF-receptor/IgG(1)Fc fusionprotein, neutralized synergistic CXCL9 production induced by TNF-alpha plus IFN-gamma, but not synergy between IFN-gamma and the TLR ligands PGN or LPS. Synovial chemokine concentrations exemplify the physiopathological relevance of the observed in vitro chemokine production patterns. In synovial fluids of patients with spondylarthropathies (ie ankylosing spondylitis or psoriatic arthritis) or rheumatoid arthritis, significantly enhanced CXCL9, but not CXCL11 levels, were detected compared to concentrations in synovial fluids of patients with metabolic crystal-induced arthritis. Thus, CXCL9 is an important chemokine in autoimmune arthritis.     

Expression of CXC chemokines and their receptors is modulated during chondrogenic differentiation of human mesenchymal stem cells grown in three-dimensional scaffold: evidence in native cartilage

Chemokines contribute to the maintenance of cartilage homeostasis. To evaluate the role of CXC chemokines CXCL8 (interleukin-8), CXCL10 (interferon-gamma-inducible protein-10), CXCL12 (stroma-derived factor-1) and CXCL13 (B-cell attracting chemokine-1) and their receptors, respectively CXCR1-2, CXCR3, CXCR4, and CXCR5, during chondrogenic differentiation of human mesenchymal stromal cells (h-MSCs), we used a well-defined in vitro model. Chondrogenic differentiation was analyzed on h-MSCs grown on hyaluronic acid-based biomaterial in the presence or absence of transforming growth factor-beta, and the expression and modulation of CXC chemokines and receptors were evaluated at different time points. Real-time polymerase chain reaction was performed to analyze their expression at the messenger ribonucleic acid (mRNA) level, and immunohistochemistry and enzyme-linked immunosorbent assay were used to evaluate their expression at the protein level. Human articular cartilage biopsies were used to evaluate chemokine and receptor expression in normal tissue. We found no expression of CXCR1, CXCR2, CXCR3, or CXCL10 at the mRNA level. CXCL8 mRNA was down-modulated, whereas at the protein level, we found greater release of this chemokine. CXCR4 and its ligand CXCL12 were down-modulated during chondrogenesis. By contrast, CXCR5 was up-regulated, whereas its ligand CXCL13 was lower. These data were also confirmed on human articular cartilage. These findings show that, during in vitro h-MSC chondrogenic differentiation, chemokine and receptor expression was specifically induced or repressed. This was in line with what the authors also found in normal articular cartilage, suggesting a role in differentiation and maturation of a cartilage-like structure in vitro and consequently the regulation of cartilage homeostasis.     

Differential expression of CXCR3 targeting chemokines CXCL10, CXCL9, and CXCL11 in different types of skin inflammation

Recruitment of activated T-cells to the skin is a common feature in a wide variety of inflammatory skin diseases. As CXCR3 activating chemokines CXCL10 (IP-10), CXCL9 (Mig), and CXCL11 (IP-9/I-TAC) specifically attract activated T-cells, this study addressed the question of whether differences in the expression of these chemokines correlate with the site and cellular composition of the skin infiltrates in different types of inflammatory skin disease. Skin biopsies from lichen planus, chronic discoid lupus erythematosus, allergic patch test reactions, psoriasis, and Jessner's lymphocytic infiltration of the skin were investigated for chemokine expression using RNA in situ hybridization, and for the expression of CXCR3 using immunohistochemistry. The results showed differential expression of CXCL10, CXCL9, and CXCL11, which correlated with differences in the localization and cellular composition of the infiltrates. Whereas CXCL10 and CXCL11 were mainly expressed by basal keratinoctyes, CXCL9 mRNA expression was located predominantly in the dermal infiltrates. Correlation with immunohistochemical data suggested that macrophages and activated keratinocytes were the main producers of these chemokines. CXCR3 was expressed by a majority of both CD4+ and CD8+ infiltrating T-cells, suggesting a functional interaction between locally produced chemokines and CXCR3-expressing T-cells. In conclusion, these findings indicate that these CXCR3 activating chemokines play a significant role in the recruitment and maintenance of T-cell infiltrates in the inflammatory skin diseases studied.     

CXCL9 and 11 in patients with pulmonary sarcoidosis: a role of alveolar macrophages

Interferon-inducible protein-10 (IP-10)/CXCL10, which is a ligand for CXC chemokine receptor 3 (CXCR3), is known to be involved in the pathogenesis of pulmonary sarcoidosis. However, the roles of monokine induced by interferon gamma (Mig)/CXCL9 and interferon-inducible T cell alpha chemoattractant (I-TAC)/CXCL11, which are also CXCR3 ligands, remain unclear. Mig/CXCL9, IP-10/CXCL10 and I-TAC/CXCL11 in both bronchoalveolar lavage fluid (BALF) and serum in patients with pulmonary sarcoidosis were measured by enzyme-linked immunosorbent assay (ELISA). The expression of these chemokines in alveolar macrophages was examined using ELISA, quantitative real-time polymerase chain reaction and immunostaining. In BALF, Mig/CXCL9 and IP-10/CXCL10 were significantly elevated in stage II sarcoidosis as compared with the levels in healthy volunteers. In serum, Mig/CXCL9 and I-TAC/CXCL11 were increased in stage II of the disease. The levels of all CXCR3 ligands in BALF were correlated with the numbers of both total and CD4(+) lymphocytes. Alveolar macrophages were stained positive for all CXCR3 ligands and produced increased amounts of these chemokines. Positive staining of the three chemokines was also observed in the epithelioid and giant cells in the sarcoid lungs. These findings suggest that Mig/CXCL9 and I-TAC/CXCL11 as well as IP-10/CXCL10 play important roles in the accumulation of Th1 lymphocytes in sarcoid lungs.     

Systemic chemokine and chemokine receptor responses are divergent in allergic versus non-allergic humans

T(h)1- and T(h)2-polarized human T cell clones display distinct patterns of chemokine receptor expression and selective chemokine responsiveness in vitro. We hypothesized that natural exposure to environmental grass pollen would induce differential systemic chemokine and chemokine receptor expression patterns in individuals with allergic rhinitis compared to healthy controls with type 2- and type 1-dominated responses to allergen respectively. To this end, we compared chemokine receptor expression on peripheral blood T cells directly ex vivo and plasma chemokine levels between these two groups of study participants prior to and during the grass pollen season. T(h)1-associated CXC chemokine receptor (CXCR) 3 was strongly expressed on >50% CD4(+)/CD45RO(+) cells of all subjects. When examined longitudinally, CXCR3 expression increased over the grass pollen season (P < 0.0001), solely in non-allergic subjects. In contrast, for both allergic and non-allergic subjects, CC chemokine receptor (CCR) 5 (T(h)1-associated) and CCR3 (T(h)2-associated) were weakly expressed on <10% of CD4(+)/CD45RO(+) cells both prior to and during the grass pollen season. Type 1 chemokines CXC chemokine ligand (CXCL) 9 and CXCL10 (monokine induced by IFN-gamma and IFN-gamma-inducible protein of 10 kDa: CXCR3 ligands), and type 2 chemokines CC chemokine ligand (CCL) 11 (eotaxin: CCR3 ligand), CCL17 (thymus and activation-regulated chemokine: CCR4 ligand) and CCL22 (monocyte-derived chemokine: CCR4 ligand) were readily detectable in the plasma of most participants. Systemic CXCL9 levels decreased from pre- to grass pollen season in allergics (P < 0.05), whereas CCL17 decreased in non-allergics (P < 0.05) over the same period. Taken together, these longitudinal data suggest a systemic shift to more intensely type 1-dominated responses in non-allergic individuals and, conversely, to more type 2-dominated responses in allergic individuals upon natural re-exposure to grass pollen.     

Chemokine expression during development of fibrosis versus resolution in a murine model of granulomatous experimental autoimmune thyroiditis

Severe granulomatous experimental autoimmune thyroiditis (G-EAT) in DBA/1 or CBA/J wild type (WT) mice at day 19 progresses to fibrosis by day 35, but severe G-EAT in DBA/1 interferon (IFN)-gamma-/- mice or less-severe G-EAT at day 19 in WT mice resolves by day 35. To study the role of chemokines in autoimmune diseases and fibrosis, profiles of chemokines and chemokine receptors were analyzed in DBA/1 WT versus IFN-gamma-/- and CBA/J thyroids, which have distinct outcomes of autoimmune inflammation. Gene expression of CXC chemokine ligand 1 (CXCL1) and CXC chemokine receptor 2 (CXCR2) paralleled neutrophil infiltration and thyrocyte destruction in DBA/1 WT or CBA/J thyroids, and gene expression of CC chemokine ligand 11 (CCL11), CCL8, and CC chemokine receptor 3 paralleled eosinophil infiltration in IFN-gamma-/- thyroids. Gene and protein expression of CXCL10, CXCL9, and CXCR3 was significantly lower in IFN-gamma-/- compared with DBA/1 WT thyroids. Moreover, immunostaining showed that CXCL10 was expressed by thyrocytes and inflammatory cells, and strong expression of CXCL10 by thyrocytes was as early as day 7. High expression of CCL2 was only observed in severely destroyed DBA/1 WT or CBA/J thyroids, which would develop fibrosis. Thus, the differential expression of chemokines may direct distinct cellular populations in DBA/1 WT versus IFN-gamma-/- thyroids. Up-regulation of CXCL10 by thyrocytes suggests its role in regulating the recruitment of specific subsets of activated lymphocytes to the thyroid during autoimmune inflammation. The early expression of CXCL1, CXCL10, and CCL2 may suggest their involvement in the initiation and perpetuation of disease in severe G-EAT thyroids, which progress to fibrosis.     

Microbial Toll-like receptor ligands differentially regulate CXCL10/IP-10 expression in fibroblasts and mononuclear leukocytes in synergy with IFN-gamma and provide a mechanism for enhanced synovial chemokine levels in septic arthritis

The CXC chemokine IFN-gamma-inducible protein-10 (IP-10/CXCL10) activates CXC chemokine receptor 3 (CXCR3) and attracts activated T cells and natural killer cells. Peripheral blood mononuclear cells (PBMC) produce low but significant amounts of IP-10/CXCL10 protein upon stimulation with double-stranded (ds) RNA, the Toll-like receptor 3 (TLR3) ligand. IFN-gamma is a superior IP-10/CXCL10inducer. The bacterial TLR4 and TLR2 ligands, LPS and peptidoglycan (PGN), inhibit IFN-gamma- or dsRNA-dependent IP-10/CXCL10 production in PBMC, whereas IL-8/CXCL8 production was enhanced. In fibroblasts a different picture emerges with IFN-gamma inducing moderate and dsRNA provoking strong IP-10/CXCL10 production. Furthermore, treatment of fibroblasts with IFN-gamma in combination with bacterial LPS or PGN results in a synergistic production of IP-10/CXCL10 and IL-8/CXCL8. The synergistic induction of IP-10/CXCL10 in fibroblasts is reflected by significantly enhanced IP-10/CXCL10 concentrations in synovial fluids of septic compared to osteoarthritis patients to reach on average higher levels than those of IL-8/CXCL8. These high amounts of IP-10/CXCL10 produced by connective tissue fibroblasts not only attract CXCR3 expressing activated Th1 cells and natural killer cells to sites of infection but may also antagonize the CCR3 dependent attraction of Th2 lymphocytes and exert CXCR3-independent, defensin-like antibacterial activity.     

胃癌组织中CXCL12和CXCR4的表达及意义

目的观察趋化因子CXCL12及其特异性受体CXCR4在人胃癌组织中的表达,探讨其与临床病理参数、预后的关系。方法选择120例胃癌标本,应用免疫组化SP法检测CXCL12和CXCR4在人胃癌组织中的表达,分析CXCL12和CXCR4的表达与患者临床病理参数、术后生存率之间的关系。结果胃癌组织及正常胃黏膜组织中均可检测到CXCL12、CXCR4的表达,但胃癌组织中的表达水平均明显高于正常胃黏膜组织,表达差异有显著性(P<0.05)。CXCL12阳性与CXCR4阳性呈正相关(r=0.276,P<0.05)。胃癌CXCL12和CXCR4的表达水平与肿瘤细胞淋巴结转移及分化程度密切相关(P<0.05),与患者的年龄、性别、肿瘤的大小、浸润深度及远处转移等无关(P>0.05)。CXCL12和CXCR4阳性表达的患者其五年生存率明显低于其阴性表达的患者。结论胃癌中CXCL12和CXCR4的高表达与胃癌的生物学行为及预后密切相关,检测其表达对预测胃癌的转移及判断预后有一定价值。     

Role of CXCL1 in tumorigenesis of melanoma

The CXC chemokine, CXCL1 (melanoma growth-stimulatory activity/growth-regulated protein alpha), plays a major role in inflammation, angiogenesis, tumorigenesis, and wound healing. Recently, chemokines have been extensively related to cellular transformation, tumor growth, homing, and metastasis. CXCL1 and its mouse homologue MIP-2 have been shown to be involved in the process of tumor formation. When chemokines such as CXCL1 and CXCL8 (IL-8) become disregulated so that they are chronically expressed, tissue damage, angiogenesis, and tumorigenesis can follow. This up-regulation of chemokines has been attributed to constitutive activation of NF-kappaB. The constitutive NF-kappaB activation is an emerging hallmark in various types of tumors including breast, colon, pancreatic, ovarian, as well as melanoma. Previous findings from our laboratory and other laboratories have demonstrated the role of endogenous activation of NF-kappaB in association with enhanced metastatic potential of malignant melanoma cells and suggest that targeting NF-kappaB may have potential therapeutic effects in clinical trials. An important step in this direction would be to delineate the important intracellular pathways and upstream kinases involved in up-regulation of NF-kappaB in melanoma cells. In this review, the signaling pathways involved in the disregulation of NF-kappaB and chemokine expression are discussed.     

Synergistic induction of CXCL9 and CXCL11 by Toll-like receptor ligands and interferon-gamma in fibroblasts correlates with elevated levels of CXCR3 ligands in septic arthritis synovial fluids

The synovial cavity constitutes the ideal stage to study the interplay between microbial Toll-like receptor (TLR) ligands and cytokines. Infiltrated leukocytes and synovial fibroblasts produce cytokine- and chemokine-induced proteases for remodeling the extracellular matrix. The regulation of chemokine function for attraction and activation of leukocytes constitutes a key feature in host immunity and resolution of inflammation after infection. Enhanced levels of the CXC chemokine ligand (CXCL9)/monokine induced by interferon-gamma (IFN-gamma) and CXCL11/IFN-inducible T cell alpha chemoattractant, two chemoattractants for activated T cells and natural killer cells, and ligands for CXC chemokine receptor 3 (CXCR3) were detected in the synovial fluid of septic arthritis compared with osteo- and crystal arthritis patients. In vitro, IFN-gamma and TLR3 ligation by double-stranded RNA (dsRNA) induced the expression of CXCL9 and CXCL11 in leukocytes and skin-muscle fibroblasts, whereas ligation of TLR2, TLR4, TLR5, and TLR9 by peptidoglycan (PGN), lipopolysaccharide (LPS), flagellin, and unmethylated CpG oligonucleotides, respectively, did not. PGN and LPS, but not unmethylated CpG oligonucleotides, even inhibited IFN-gamma-induced CXCL9 and CXCL11 expression in leukocytes. In sharp contrast, in fibroblasts, the TLR ligands PGN, dsRNA, LPS, and flagellin synergized with IFN-gamma for the production of CXCL9 and CXCL11. Although TLR ligands stimulate leukocytes to produce CXCL8/interleukin-8 during the early innate defense, they contribute less to the production of CXCR3 ligands, whereas fibroblasts are important sources of CXCR3 ligands. These results illustrate the complex interaction between cytokines and TLR ligands in infection.     

Abundant expression of CXCL9 (MIG) by stromal cells that include dendritic cells and accumulation of CXCR3+ T cells in lymphocyte-rich gastric carcinoma

The neoplastic environment is generally regarded as an immunosuppressive milieu. However, a group of cancers are characterized by the abundance of tumour-infiltrating lymphocytes (TILs). Here we examined the possible roles of chemokines in the formation of lymphoid stroma in lymphocyte-rich gastric carcinomas (GCs), including EBV(+) cases and conventional GCs. Regardless of EBV positivity, TILs in lymphocyte-rich GCs predominantly expressed CXCR3, while its ligand CXCL9 was abundantly expressed by stromal cells and a portion of cancer cells. CXCL9(+) stromal cells were judged to include dendritic cells, because they partly co-expressed fascin, DC-sign, CD83, DC-lamp or HLA-DR. T cells in close contact with CXCL9(+) cells showed frequent labelling of Ki-67 (approximately 10%), suggesting the immunostimulatory activity of CXCL9(+) stromal cells. The T-cell zone of the regional lymph nodes of lymphocyte-rich GCs also abounded with CXCR3(+) T cells and CXCL9(+) stromal cells. This indicated a close similarity between cancer stroma and regional lymph nodes of lymphocyte-rich GCs. Quantitative RT-PCR also confirmed the strong expression of CXCR3, CXCL9 and IFNgamma in lymphocyte-rich GCs. In contrast, conventional GCs contained less abundant CXCR3(+) T cells and few CXCL9(+) stromal cells. Collectively, the CXCL9-CXCR3 axis plays a pivotal role in the formation of lymphoid stroma in lymphocyte-rich GCs. Given similar findings in the regional lymph nodes, the lymphoid stroma of lymphocyte-rich GCs may represent a tertiary lymphoid tissue with predominantly Th1-shifted immune responses.     

CXCR1-binding chemokines in inflammatory bowel diseases: down-regulated IL-8/CXCL8 production by leukocytes in Crohn's disease and selective GCP-2/CXCL6 expression in inflamed intestinal tissue

Crohn's disease (CD) and ulcerative colitis (UC) are inflammatory bowel diseases (IBD) that are characterized by chronic intestinal inflammation and a constant influx of leukocytes mediated by pro-inflammatory cytokines and chemokines. The intestinal expression of the CXCR1-binding chemokines IL-8/CXCL8 and GCP-2/CXCL6 and the participation of immunocompetent cells in IBD were evaluated. IL-8 production by peripheral blood mononuclear cells (PBMC) from IBD patients, stimulated with endotoxin, plant lectin or double-stranded RNA, was significantly lowered in patients with CD, but not in UC patients or healthy subjects. The reduced chemokine production by PBMC from IBD patients was both IL-8 and CD specific, but not inducer dependent. In serum, most chemokines remained undetectable, while the levels of those that were measurable remained unaltered in IBD patients. GCP-2, but not ENA-78/CXCL5, nor IL-8, were highly expressed by endothelial cells in inflamed intestinal tissue of IBD patients. In contrast, stimulated endothelial cell cultures produced more IL-8 than GCP-2. The selective GCP-2 staining of endothelial cells at sites of ulcerations suggests that GCP-2, despite its low production capacity in vitro, plays a role in IBD that is different from that of structurally (ENA-78) and functionally (IL-8) related ELR(+) CXC chemokines. Thus, the chemokine network shows complementarity rather than redundancy.     

CXCL13与恶性肿瘤的研究进展

CXC亚家族趋化因子13(CXCL13)是CXC趋化因子家族成员之一.CXCL13能与其特异性受体CXCR5结合,趋化CXCR5+的成熟B细胞、滤泡辅助性T细胞 、树突状细胞以及巨噬细胞,在适应性免疫中发挥重要作用.一直以来,人们认为CXCL13能促进恶性肿瘤的发生、发展和转移,但近年来部分关于CXCL13与恶性肿瘤关系的研究证实CXCL13在恶性肿瘤的治疗中也发挥着重要的作用.因此研究C X C L 13的一般生物学特性及其与恶性肿瘤的关系具有重要意义.