Chemokine mRNA expression in gastric mucosa is associated with Helicobacter pylori cagA positivity and severity of gastritis.
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AIM: To investigate the association between the quantity of gastric chemokine mRNA expression, severity of gastritis, and cagA positivity in Helicobacter pylori associated gastritis. METHODS: In 83 dyspeptic patients, antral and corpus biopsies were taken for semiquantitative reverse transcription polymerase chain reaction (RT-PCR) and histological grading of gastritis. Gastritis was evaluated by visual analogue scales. Quantities of chemokine (IL-8, GRO alpha, ENA-78, RANTES, MCP-1) RT-PCR products were compared with G3PDH products. Each sample was also evaluated for the presence of cagA and ureA mRNA by RT-PCR. RESULTS: mRNA expression of all five chemokines was significantly greater in H pylori positive than in H pylori negative mucosa. In H pylori positive patients, in the antrum C-X-C chemokine mRNA expression was significantly greater in cagA positive patients than in cagA negative patients, but there were no significant differences in C-C chemokine mRNA expression. In H pylori positive patients, chemokine mRNA expression in the corpus was less than in the antrum. In contrast to the antrum, only GRO alpha mRNA expression was significantly greater in cagA positive infection. Polymorphonuclear cell infiltration was correlated with C-X-C chemokine mRNA expression. Significant correlations were also found between bacterial density and C-X-C chemokine mRNA expression. CONCLUSIONS: In H pylori infection, C-X-C chemokines may play a primary role in active gastritis. Infection with cagA positive H pylori induces greater gastric chemokine mRNA expression in the antral mucosa, which may be relevant to the increased mucosal damage associated with cagA positive H pylori infection. (+info)
Isolation of novel GRO genes and a phylogenetic analysis of the CXC chemokine subfamily in mammals.
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Approximately 15 different alpha, or CXC, chemokines have thus far been isolated from 11 species of mammals. Among the best studied chemokines are the 12 human proteins that are encoded by 11 paralogous genes. In order to better understand the evolution and function of this group of genes, we isolated and characterized six novel GRO and GRO-related cDNA sequences from the cow (Bos taurus), the sheep (Ovis aries), the rabbit (Oryctolagus cuniculus), and the guinea pig (Cavia porcellus). The amino acid sequence of the diverged guinea pig GRO or KC gene is only 50%-60% similar to presumed orthologs from other species, while the sheep and cow GRO proteins are 90%-99% similar to each other. The presence of multiple GRO genes in the cow, the rabbit, and the sheep is consistent with what has been observed for humans. Phylogenetic analyses of amino acid sequences from 44 proteins indicate that genes orthologous to many of the 11 known from humans exist in other species. One such gene, interleukin 8, or IL8, has been isolated from nine species, including the rodent guinea pig; however, this gene is absent in the rat and the mouse, indicating a unique gene loss event in the rat/mouse (muroid rodent) lineage. The KC (or MIP2) gene of rodents appears to be orthologous to the GRO gene found in other taxonomic orders. Combined evidence from different sources suggests that IP10 and MIG share sister taxon relationships on the evolutionary tree, while the remaining paralogous genes represent independent lineages, with limited evidence for kinship between them. This observation indicates that these genes originated nearly contemporaneously via a series of gene duplication events. Relative-rate tests for synonymous and nonsynonymous nucleotide substitutions in the KC and IL8 genes did not detect rate heterogeneity; however, there are several notable features regarding the IL8 genes. For example, the IL8 proteins from two Old World monkeys are as similar to one another as they are to the IL8 protein from humans, and all observed nucleotide differences between the IL8 genes of the two monkeys cause amino acid changes; in other words, there are no synonymous differences between them. (+info)
Selective recruitment of CCR4-bearing Th2 cells toward antigen-presenting cells by the CC chemokines thymus and activation-regulated chemokine and macrophage-derived chemokine.
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Helper T cells are classified into Th1 and Th2 subsets based on their profiles of cytokine production. Th1 cells are involved in cell-mediated immunity, whereas Th2 cells induce humoral responses. Selective recruitment of these two subsets depends on specific adhesion molecules and specific chemoattractants. Here, we demonstrate that the T cell-directed CC chemokine thymus and activation-regulated chemokine (TARC) was abundantly produced by monocytes treated with granulocyte macrophage colony stimulating factor (GM-CSF) or IL-3, especially in the presence of IL-4 and by dendritic cells derived from monocytes cultured with GM-CSF + IL-4. The receptor for TARC and another macrophage/dendritic cell-derived CC chemokine macrophage-derived chemokine (MDC) is CCR4, a G protein-coupled receptor. CCR4 was found to be expressed on approximately 20% of adult peripheral blood effector/memory CD4+ T cells. T cells attracted by TARC and MDC generated cell lines predominantly producing Th2-type cytokines, IL-4 and IL-5. Fractionated CCR4+ cells but not CCR4- cells also selectively gave rise to Th2-type cell lines. When naive CD4+ T cells from adult peripheral blood were polarized in vitro, Th2-type cells selectively expressed CCR4 and vigorously migrated toward TARC and MDC. Taken together, CCR4 is selectively expressed on Th2-type T cells and antigen-presenting cells may recruit Th2 cells expressing CCR4 by producing TARC and MDC in Th2-dominant conditions. (+info)
Prospects for cytokine and chemokine biotherapy.
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Cytokines with immunostimulating effects have the capacity to induce tumor immunity in animal models, whereas some cytokines interfere with tumor growth based on their angiostatic effects. Despite these capabilities, cytokines, such as IFN-, IFN-, tumor necrosis factor, interleukin (IL)-1, and IL-2, have had limited clinical efficacy and many undesirable side effects. In preclinical models, cytokines can even promote tumor growth and increase metastatic spread. Although chemokines have had limited clinical evaluation, studies of animal models show that they can also have tumor-suppressive or tumor-enhancing effects. In mice, chemokines, such as IP-10, RANTES, and TCA3, have resulted in tumor regression and immunity to subsequent tumor challenge. Those chemokines that are angiostatic (e.g., PF4, IP-10, and MIG) can also induce tumor regression by reducing the tumor blood supply. Conversely, IL-8, which is angiogenic, can promote tumor growth. Our studies show that nasopharyngeal cell line cells (FADU) show a chemotactic as well as a proliferative response to MCP-1. In addition, a variant murine T cell lymphoma cell line Esb-MP, unlike the parental variant Esb, was selectively chemoattracted by murine MCP-1/JE. When injected s.c. into mice, the Esb-MP variant metastasized to the kidney with much higher frequency than the Esb variant. Both cultured kidneys from normal mice and a mesangial cell line constitutively produced chemoattractants that acted on Esb-MP but not Esb parental cells. Purification to homogeneity of these chemoattractants led to the identification of RANTES and JE. These results demonstrate that some chemokines may promote tumor growth and organ-specific metastatic spread of those tumors that have adapted and become responsive to chemokines. Finally, tumors appear to use numerous adaptive mechanisms to subvert and suppress the immune system. More effective therapy with cytokines and chemokines will require better characterization of the means by which tumors develop resistance to cytokines and overcome the immune system. Only then can we develop appropriate therapeutic approaches to antagonize cancer-induced immunosuppression. (+info)
An in vitro coculture model system was used to explore conditions that trigger neutrophil chemotaxis to Chlamydia trachomatis infected human epithelial cells (HEC-1B). Polarized HEC-1B monolayers growing on extracellular matrix (ECM) were infected with C. trachomatis serovar E. By 36 h, coincident with the secretion of chlamydial lipopolysaccharide and major outer membrane protein to the surfaces of infected cells, human polymorphonuclear neutrophils (PMNL) loaded with azithromycin migrated through the ECM and infiltrated the HEC-1B monolayer. Bioreactive azithromycin was delivered by the chemotactic PMNL to infected epithelial cells in concentrations sufficient to kill intracellular chlamydiae. However, residual chlamydial envelopes persisted for 4 weeks, and PMNL chemotaxis was triggered to epithelial cells containing residual envelopes. Infected endometrial cells demonstrated up-regulation of ENA-78 and GCP-2 chemokine mRNA. Thus, despite appropriate antimicrobial therapy, residual chlamydial envelope antigens may persist in infected tissues of culture-negative women and provide one source for sustained inflammation. (+info)
Mechanisms of acute inflammatory lung injury induced by abdominal sepsis.
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Sequestration of neutrophils and release of histotoxic mediators are considered important for the development of pathologic alterations of the lung defined as adult respiratory distress syndrome. Mechanisms of inflammatory lung injury caused by abdominal sepsis were investigated using the colon ascendens stent peritonitis (CASP) model that closely mimics the human disease. In the CASP model, a continuous leakage of intraluminal bacteria into the peritoneal cavity is induced by implantation of a stent in the ascending colon, generating a septic focus. In contrast to the cecal ligation and puncture model of peritonitis, survival of mice following CASP surgery is dependent on IFN-gamma, but independent of tumor necrosis factor (TNF). Here we show that the systemic inflammation induced by CASP surgery results in a rapid and profound increase of lung vascular permeability that was associated with the activation and recruitment of neutrophils to the lung. Activation of circulating granulocytes was characterized by increased production of serine proteinases and reactive oxygen metabolites, as well as elevated expression of cell surface Mac-1. Expression of MIP-2, KC, MIP-1alpha and E-selectin mRNA in lung was strongly increased within 3 h following CASP surgery, whereas up-regulation of IP-10, MCP-1 and P-selectin was delayed. In contrast, induction of RANTES, LIX, ICAM-1 and VCAM-1 mRNA was weak or not detectable after CASP surgery. Importantly, recruitment of leukocytes to the lung was normal in lipopolysaccharide-resistant mice, and was not affected by antibody neutralization of TNF or the chemokines MIP-2 and KC. (+info)
Chemokine expression in CF epithelia: implications for the role of CFTR in RANTES expression.
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To delineate the mechanisms that facilitate leukocyte migration into the cystic fibrosis (CF) lung, expression of chemokines, including interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), and RANTES, was compared between CF and non-CF airway epithelia. The findings presented herein demonstrate that, under either basal conditions or tumor necrosis factor-alpha (TNF-alpha)- and/or interferon-gamma (IFN-gamma)-stimulated conditions, a consistent pattern of differences in the secretion of IL-8 and MCP-1 between CF and non-CF epithelial cells was not observed. In contrast, CF epithelial cells expressed no detectable RANTES protein or mRNA under basal conditions or when stimulated with TNF-alpha and/or IFN-gamma (P +info)
Cutting edge: clustered AU-rich elements are the target of IL-10-mediated mRNA destabilization in mouse macrophages.
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In the present study we show that IL-10-mediated inhibition of inflammatory gene expression can be mediated by an AU-rich element (ARE) cluster present in the 3' untranslated region (3'UTR) of sensitive genes. A series of chloramphenicol acetyl transferase (CAT) reporter gene constructs were prepared in which different fragments from the IL-10-sensitive KC mRNA 3'UTR were placed downstream of the coding region of the reporter gene CAT. CAT mRNA containing the KC 3'UTR was markedly destabilized as compared with the control CAT mRNA, and the decay rate was further increased in cells stimulated with IL-10. The KC 3'UTR contains an ARE cluster and three isolated ARE motifs. The ARE cluster spanning nucleotides 378-399 appeared to be both necessary and sufficient to mediate sensitivity to IL-10 because a 116-nucleotide fragment that contains the cluster conferred sensitivity, while mutation of the sequence between positions 378 and 399 eliminated sensitivity. The destabilizing effect of IL-10 was relatively selective, as the stability of chimeric CAT mRNAs was not modulated in cells treated with IFN-gamma or IL-4. (+info)