Seric chemokines and chemokine receptors in eosinophils during acute human schistosomiasis mansoni

The recruitment of circulating eosinophils by chemokines and chemokine receptors plays an important role in the inflammation process in acute human schistosomiasis. Our main focus has been on the plasma chemokines (CXCL8/CCL2/CCL3/CCL24) and chemokine receptors (CCR2/CCR3/CCR5/CXCR1/CXCR2/CXCR3/CXCR4) expressed by circulating eosinophils from acute Schistosoma mansoni infected patients (ACT). Our studies compared ACT patients and healthy individuals as a control group. Our major findings demonstrated a plethora of chemokine secretion with significantly increased secretion of all chemokines analysed in the ACT group. Although no differences were detected for beta-chemokine receptors (CCR2, CCR3 and CCR5) or alpha-chemokine receptors (CXCR3 and CXCR4), a significantly lower frequency of CXCR1+ and CXCR2+ eosinophils in the ACT group was observed. The association between chemokines and their chemokine receptors revealed that acutely infected schistosome patients displaying decreased plasma levels of CCL24 are the same patients who presented enhanced secretion of CCL3, as well as increased expression of both the CCR5 and CXCR3 chemokine receptors. These findings suggest that CCL24 may influence the kinetics of chemokines and their receptors and eosinophils recruitment during human acute schistosomiasis mansoni.

The effect of combined polymorphisms in chemokines and chemokine receptors on the clinical course of HIV-1 infection in a Brazilian population

Polymorphisms in genes that encode chemokines or their receptors can modulate susceptibility to human immunodeficiency virus (HIV) infection and disease progression. The objective of this study was to assess the frequency of polymorphisms CCR5-Δ32, CCR2-64I, CCR5-59029A and SDF1-3'A and their role in the course of HIV infection in a Southern Brazilian population. Clinical data were obtained from 249 patients for an average period of 6.4 years and genotypes were determined by standard polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism. Survival analyses were conducted for three outcomes: CD4+ T-cell counts below 200 cells/µL, acquired immune deficiency syndrome (AIDS) or death. The frequency of the polymorphisms CCR5-Δ32, CCR2-64I, CCR5-59029A and SDF1-3'A were 0.024, 0.113, 0.487 and 0.207, respectively. CCR5-Δ32 was associated with a reduction in the risk for CD4+ T-cell depletion and with an increased risk for death after AIDS diagnosis. CCR2-64I was associated with a reduction in the risk for developing AIDS. SDF1-3'A was also associated with decreased risk for AIDS, but its effect was only evident when CCR2-64I was present as well. These results highlight the possibility of using these markers as indicators for the prognosis of disease progression and provide evidence for the importance of analysing the effects of gene polymorphisms in a combined fashion.

Dengue-2 and yellow fever 17DD viruses infect human dendritic cells, resulting in an induction of activation markers, cytokines and chemokines and secretion of different TNF-α and IFN-α profiles

Flaviviruses cause severe acute febrile and haemorrhagic infections, including dengue and yellow fever and the pathogenesis of these infections is caused by an exacerbated immune response. Dendritic cells (DCs) are targets for dengue virus (DENV) and yellow fever virus (YF) replication and are the first cell population to interact with these viruses during a natural infection, which leads to an induction of protective immunity in humans. We studied the infectivity of DENV2 (strain 16681), a YF vaccine (YF17DD) and a chimeric YF17D/DENV2 vaccine in monocyte-derived DCs in vitro with regard to cell maturation, activation and cytokine production. Higher viral antigen positive cell frequencies were observed for DENV2 when compared with both vaccine viruses. Flavivirus-infected cultures exhibited dendritic cell activation and maturation molecules. CD38 expression on DCs was enhanced for both DENV2 and YF17DD, whereas OX40L expression was decreased as compared to mock-stimulated cells, suggesting that a T helper 1 profile is favoured. Tumor necrosis factor (TNF)-α production in cell cultures was significantly higher in DENV2-infected cultures than in cultures infected with YF17DD or YF17D/DENV. In contrast, the vaccines induced higher IFN-α levels than DENV2. The differential cytokine production indicates that DENV2 results in TNF induction, which discriminates it from vaccine viruses that preferentially stimulate interferon expression. These differential response profiles may influence the pathogenic infection outcome.

Chemokines and chemokine receptors expression in the lesions of patients with American cutaneous leishmaniasis

American cutaneous leishmaniasis (ACL) presents distinct active clinical forms with different grades of severity, known as localised (LCL), intermediate (ICL) and diffuse (DCL) cutaneous leishmaniasis. LCL and DCL are associated with a polarised T-helper (Th)1 and Th2 immune response, respectively, whereas ICL, or chronic cutaneous leishmaniasis, is associated with an exacerbated immune response and a mixed cytokine expression profile. Chemokines and chemokine receptors are involved in cellular migration and are critical in the inflammatory response. Therefore, we evaluated the expression of the chemokines CXCL10, CCL4, CCL8, CCL11 and CXCL8 and the chemokine receptors CCR3, CXCR3, CCR5 and CCR7 in the lesions of patients with different clinical forms of ACL using immunohistochemistry. LCL patients exhibited a high density of CXCL10+, CCL4+ and CCL8+ cells, indicating an important role for these chemokines in the local Th1 immune response and the migration of CXCR3+ cells. LCL patients showed a higher density of CCR7+ cells than ICL or DCL patients, suggesting major dendritic cell (DC) migration to lymph nodes. Furthermore, DCL was associated with low expression levels of Th1-associated chemokines and CCL11+ epidermal DCs, which contribute to the recruitment of CCR3+ cells. Our findings also suggest an important role for epidermal cells in the induction of skin immune responses through the production of chemokines, such as CXCL10, by keratinocytes.

The T cell-specific CXC chemokines IP-10, Mig, and I-TAC are expressed by activated human bronchial epithelial cells.

Recruitment of activated T cells to mucosal surfaces, such as the airway epithelium, is important in host defense and for the development of inflammatory diseases at these sites. We therefore asked whether the CXC chemokines IFN-induced protein of 10 kDa (IP-10), monokine induced by IFN-gamma (Mig), and IFN-inducible T-cell alpha-chemoattractant (I-TAC), which specifically chemoattract activated T cells by signaling through the chemokine receptor CXCR3, were inducible in respiratory epithelial cells. The effects of proinflammatory cytokines, including IFN-gamma (Th1-type cytokine), Th2-type cytokines (IL-4, IL-10, and IL-13), and dexamethasone were studied in normal human bronchial epithelial cells (NHBEC) and in two human respiratory epithelial cell lines, A549 and BEAS-2B. We found that IFN-gamma, but not TNF-alpha or IL-1 beta, strongly induced IP-10, Mig, and I-TAC mRNA accumulation mainly in NHBEC and that TNF-alpha and IL-1 beta synergized with IFN-gamma induction in all three cell types. High levels of IP-10 protein (> 800 ng/ml) were detected in supernatants of IFN-gamma/TNF-alpha-stimulated NHBEC. Neither dexamethasone nor Th2 cytokines modulated IP-10, Mig, or I-TAC expression. Since IFN-gamma is up-regulated in tuberculosis (TB), using in situ hybridization we studied the expression of IP-10 in the airways of TB patients and found that IP-10 mRNA was expressed in the bronchial epithelium. In addition, IP-10-positive cells obtained by bronchoalveolar lavage were significantly increased in TB patients compared with normal controls. These results show that activated bronchial epithelium is an important source of IP-10, Mig, and I-TAC, which may, in pulmonary diseases such as TB (in which IFN-gamma is highly expressed) play an important role in the recruitment of activated T cells.

Acquired antibody responses against Plasmodium vivax infection vary with host genotype for duffy antigen receptor for chemokines (DARC).

BACKGROUND: Polymorphism of the Duffy Antigen Receptor for Chemokines (DARC) is associated with susceptibility to and the severity of Plasmodium vivax malaria in humans. P. vivax uses DARC to invade erythrocytes. Individuals lacking DARC are 'resistant' to P. vivax erythrocytic infection. However, susceptibility to P. vivax in DARC+ individuals is reported to vary between specific DARC genotypes. We hypothesized that the natural acquisition of antibodies to P. vivax blood stages may vary with the host genotype and the level of DARC expression. Furthermore, high parasitemia has been reported to effect the acquisition of immunity against pre-erythrocytic parasites. We investigated the correlation between host DARC genotypes and the frequency and magnitude of antibodies against P. vivax erythrocytic stage antigens. METHODOLOGY/FINDINGS: We assessed the frequencies and magnitudes of antibody responses against P. vivax and P. falciparum sporozoite and erythrocytic antigens in Colombian donors from malaria-endemic regions. The frequency and level of naturally-acquired antibodies against the P. vivax erythrocytic antigens merozoite surface protein 1 (PvMSP1) and Duffy binding protein (PvDBP) varied with the host DARC genotypes. Donors with one negative allele (FY*B/FY*Bnull and FY*A/FY*Bnull) were more likely to have anti-PvMSP1 and anti-PvDBP antibodies than those with two positive alleles (FY*B/FY*B and FY*A/FY*B). The lower IgG3 and IgG1 components of the total IgG response may account for the decreased responses to P. vivax erythrocytic antigens with FY*A/FY*B and FY*B/FY*B genotypes. No such association was detected with P. falciparum erythrocytic antigens, which does not use DARC for erythrocyte invasion. CONCLUSION/SIGNIFICANCE: Individuals with higher DARC expression, which is associated with higher susceptibility to P. vivax infection, exhibited low frequencies and magnitudes of P. vivax blood-stage specific antibody responses. This may indicate that one of the primary mechanisms by which P. vivax evades host immunity is through DARC indirectly down-regulating humoral responses against erythrocytic invasion and development.

Chemokines in neuroectodermal cancers: the crucial growth signal from the soil.

Although chemokines and their receptors were initially identified as regulators of cell trafficking during inflammation and immune response, they have emerged as crucial players in all stages of tumor development, primary growth, migration, angiogenesis, and establishment as metastases in distant target organs. Neuroectodermal tumors regroup neoplasms originating from the embryonic neural crest cells, which display clinical and biological similarities. These tumors are highly malignant and rapidly progressing diseases that disseminate to similar target organs such as bone marrow, bone, liver and lungs. There is increasing evidence that interaction of several chemokine receptors with corresponding chemokine ligands are implicated in the growth and invasive characteristics of these tumors. In this review we summarize the current knowledge on the role of CXCL12 chemokine and its CXCR4 and CXCR7 receptors in the progression and survival of neuroectodermal tumors, with particular emphasis on neuroblastoma, the most typical and enigmatic neuroectodermal childhood tumor.

Changing responsiveness to chemokines allows medullary plasmablasts to leave lymph nodes.

During T cell-dependent antibody responses lymph node B cells differentiate either to plasmablasts that grow in the medullary cords, or to blasts that proliferate in follicles forming germinal centers. Many plasmablasts differentiate to plasma cells locally, but some leave the medullary cords and migrate to downstream lymph nodes. To assess the basis for this migration, changes in the responsiveness of B cells to a range of chemokines have been studied as they differentiate. Naive B cells express high levels of CCR6, CCR7, CXCR4 and CXCR5. When activated B cells grow in follicles the expression of these chemokine receptors and the responsiveness to the respective chemokines is retained. During the extrafollicular response, plasmablast expression of CXCR5 and responsiveness to B-lymphocyte chemoattractant (CXCR5) as well as to secondary lymphoid tissue chemokine (CCR7) and stromal cell-derived factor (SDF)-1 (CXCR4) are lost while a weak response towards the CCR6 chemokine LARC is maintained. Despite losing responsiveness to SDF-1, extrafollicular plasmablasts still express high levels of CXCR4 on the cell surface. These results suggest that the combined loss of chemokine receptor expression and of chemokine responsiveness may be a necessary prerequisite for cells to migrate to the medullary cords and subsequently enter the efferent lymph.

Complex interplay between LPS and IL-10 in dendritic cells: uncoupling of inflammatory chemokine receptors and positive effects on B cell chemokines

Abstract: Protective immune responses against pathogen invasion and transformed cells requires the coordinated action of distinct leukocyte subsets and soluble factors, overall termed immunological network. Among antigen-presenting cells (APC), a crucial role is played by dendritic cells (DC), which initiate, amplify and determine the outcome of the immune response. Micro-environmental conditions profoundly influence DC in such ways that the resulting immune response ranges from successful immune stimulation to abortive response or immune suppression. For instance, the presence in the milieu of anti-inflammatory cytokine interleukin-10 (IL-10) reverts most of the effects mediated on DC by even strong pro-inflammatory agents such as bacterial Lipopolysaccharide (LPS), in terms of differentiation, activation and functions. In an environment containing both LPS and IL-10, uncoupling of receptors for inflammatory chemokines already occurs after a few hours and in a reversible manner on DC, allowing scavenging of chemokines and, consequently, attenuation of the inflammatory process which could be deleterious to the organism. By studying the effects on DC of concomitant stimulation by LPS and IL-10 from the gene expression point of view, we were able to define four distinct transcriptional programs: A. the inhibition of inflammation and immunity, B. the regulation of tissue remodeling, C. the tuning of cytokine/growth factor receptors and G protein-coupled receptors, D. the stimulation of B cell function and lymphoid tissue neogenesis. Among the latter genes, we further demonstrated that IL-10 synergizes with Toll-like receptor ligands for the production of functionally active B cell attracting chemokine CXCL13. Our data provide evidence that the combined exposure of APC to LPS and IL-10, via the production of CXCL13, involves humoral immunity by attracting antibody-producing cells. It is well known that the persistent release of CXCL13 leads to the development of ectopic lymphoid tissue aggregates and production of high levels of antibodies, thus favoring the induction of auto-immunity. Our findings suggest that the IL-10 produced in chronic inflammatory conditions may promote lymphoid tissue neogenesis through increased release of CXCL13. IL-10 is an anti-inflammatory cytokine inhibiting cellular-mediated TH 1-polarized immune responses. In this study we demonstrate that IL- 10 strongly supports the development of humoral immunity. IL-10 and CXCL13 can thus be targets for specific therapies in auto-immune diseases.

The chemokines CCL19 and CCL21 and their role in T and dendritic cell biology

Summary : The chemokines CCL19 and CCL21 and their common receptor CCR7 attract antigenpresenting dendritic cells (DCs) and naive T cells into the T zone of secondary lymphoid organs (SLO) and are therefore critically involved in homeostatic T cell recirculation and the initiation of adaptive immune responses. In addition. CCR7 ligands were proposed to mediate T cell exit from neonatal thymus, allowing colonization of T zones in SLOB. The relative contribution of CCL19 and CCL21 to these processes has remained unclear, as they were studied in mouse models lacking either CCR7 or both ligands. The aim of my thesis was to characterize Cc119-' mice and thereby investigate the relative roles of the two CCR7 ligands in development, homeostasis and immune response. The first study addressed the role of CCR7 ligands in DC biology. We found that CCL19 is dispensable for DC migration to lymph nodes and their localization to T zones. Furthermore, a CCL19-deficient environment did not lead to a defect in DC maturation or T cell priming. Therefore, CCL21 is sufficient to mediate CCR7-dependent processes during the initiation of adaptive immune responses. In the second study we investigated how the two CCR7 ligands affect CCR7 expression and function on naive T cells. We found that in SLOB CCR7 is constantly occupied with CCL19 and CCL21, eventually leading to its internalization. The reduced level of free CCR7 on these cells led to diminished ligand sensitivity and consequently impaired chemotactic responses. This effect was reversible by passage through aCCR7 ligand-free environment like the blood circulation. We propose that the different states of ligand sensitivity in SLOB and blood are important to allow for proper T cell recirculation. In the third study the role of CCL19 in neonatal thymus and spleen was analyzed. While neonatal Cc119-!- mice had no defect in thymic egress, we observed reduced T cell accumulation in the spleen but not lymph nodes. We identified reticular stromal cells in the developing white pulp (WP) as the major CCL 19 source. The development of these WP stromal cells as well as their CCL19 expression were dependent on LTalß2+ B cells. In conclusion, we have found that CCL21 can mostly compensate for lack of CCL19 in homeostasis and immunity. In contrast, during development. CCL19 has anon-redundant function for T cell colonization of the spleen.

Identification of ectodysplasin target genes reveals the involvement of chemokines in hair development.

Ectodysplasin (Eda), a member of the tumor necrosis factor (Tnf) family, regulates skin appendage morphogenesis via its receptor Edar and transcription factor NF-κB. In humans, inactivating mutations in the Eda pathway components lead to hypohidrotic ectodermal dysplasia (HED), a syndrome characterized by sparse hair, tooth abnormalities, and defects in several cutaneous glands. A corresponding phenotype is observed in Eda-null mice, where failure in the initiation of the first wave of hair follicle development is a hallmark of HED pathogenesis. In an attempt to discover immediate target genes of the Eda/NF-κB pathway, we performed microarray profiling of genes differentially expressed in embryonic skin explants after a short exposure to recombinant Fc-Eda protein. Upregulated genes included components of the Wnt, fibroblast growth factor, transforming growth factor-β, Tnf, and epidermal growth factor families, indicating that Eda modulates multiple signaling pathways implicated in skin appendage development. Surprisingly, we identified two ligands of the chemokine receptor cxcR3, cxcl10 and cxcl11, as new hair-specific transcriptional targets of Eda. Deficiency in cxcR3 resulted in decreased primary hair follicle density but otherwise normal hair development, indicating that chemokine signaling influences the patterning of primary hair placodes only.

Long synthetic peptides as biologically active proteins: the example of the chemokines.

Chemokines constitute an expanding protein family of over 40 members which exhibit a wide variety of biological activities and are involved in many normal physiological processes, such as cellular migration, differentiation and activation, but also in pathological situations, such as inflammation and metastasis. Over the last few years, we have developed methods to manufacture long synthetic peptides of up to 130 residues, and to achieve the formation of native-like cysteine pairings. This ability prompted us to undertake the total chemical synthesis of chemokines. So far, we have successfully produced over 30 chemokine species, which exhibit biological activities similar to, or greater than, those reported by others. Chemical synthesis offers a clear advantage over recombinant technologies for the introduction of fluorochromes and haptens at molecularly defined positions. In addition, approval of chemically synthesized products for use in humans is straightforward compared with material produced by biological methods.

Chemokines induce axon outgrowth downstream of Hepatocyte Growth Factor and TCF/β-catenin signaling

Axon morphogenesis is a complex process regulated by a variety of secreted molecules, including morphogens and growth factors, resulting in the establishment of the neuronal circuitry. Our previous work demonstrated that growth factors [Neurotrophins (NT) and Hepatocyte Growth Factor (HGF)] signal through β-catenin during axon morphogenesis. HGF signaling promotes axon outgrowth and branching by inducing β-catenin phosphorylation at Y142 and transcriptional regulation of T-Cell Factor (TCF) target genes. Here, we asked which genes are regulated by HGF signaling during axon morphogenesis. An array screening indicated that HGF signaling elevates the expression of chemokines of the CC and CXC families. In line with this, CCL7, CCL20, and CXCL2 significantly increase axon outgrowth in hippocampal neurons. Experiments using blocking antibodies and chemokine receptor antagonists demonstrate that chemokines act downstream of HGF signaling during axon morphogenesis. In addition, qPCR data demonstrates that CXCL2 and CCL5 expression is stimulated by HGF through Met/b-catenin/TCF pathway. These results identify CC family members and CXCL2 chemokines as novel regulators of axon morphogenesis downstream of HGF signaling.

Cytokine-induced sleep: Neurons respond to TNF with production of chemokines and increased expression of Homer1a in vitro.

Interactions of neurons with microglia may play a dominant role in sleep regulation. TNF may exert its somnogeneic effects by promoting attraction of microglia and their processes to the vicinity of dendrites and synapses. We found TNF to stimulate neurons (i) to produce CCL2, CCL7 and CXCL10, chemokines acting on mononuclear phagocytes and (ii) to stimulate the expression of the macrophage colony stimulating factor (M-CSF/Csf1), which leads to elongation of microglia processes. TNF may also act on neurons by affecting the expression of genes essential in sleep-wake behavior. The neuronal expression of Homer1a mRNA, increases during spontaneous and enforced periods of wakefulness. Mice with a deletion of Homer1a show a reduced wakefulness with increased non-rapid eye movement (NREM) sleep during the dark period. Recently the TNF-dependent increase of NREM sleep in the dark period of mice with CD40-induced immune activation was found to be associated with decreased expression of Homer1a. In the present study we investigated the effects of TNF and IL-1β on gene expression in cultures of the neuronal cell line HT22 and cortical neurons. TNF slightly increased the expression of Homer1a and IL-1β profoundly enhanced the expression of Early growth response 2 (Egr2). The data presented here indicate that the decreased expression of Homer1a, which was found in the dark period of mice with CD40-induced increase of NREM sleep is not due to inhibitory effects of TNF and IL-1β on the expression of Homer1a in neurons.