Molecular identification and expression analysis of the CC chemokine gene in rock bream (Oplegnathus fasciatus) and the biological activity of the recombinant protein

We identified the CC chemokine cDNA designated as RbCC1 (CC chemokine 1 in rock bream, Oplegnathus fasciatus), which was isolated using expressed sequence tag (EST) analysis of a lipopolysaccharide (LPS)-stimulated rock bream liver cDNA library. The full-length RbCC1 cDNA (850 bp) contained an open reading frame (ORF) of 366 bp encoding 122 amino acids. Results from our phylogenetic analysis demonstrated that the RbCC1 was closest relationship to the orange-spotted grouper and Mi-iyu croaker CC chemokines located within the fish CC chemokine group. RbCC1 was significantly expressed in the intestine, spleen, liver, and PBLs (peripheral blood leukocytes). Rock bream PBLs were stimulated with several mitogens, LPS and Con A/PMA which significantly induced the expression of RbCC1 mRNA in the PBLs. The RbCC1 mRNA expression in several tissues under conditions of bacterial and viral challenge was examined. The experimental challenge revealed that the kidney and spleen of fish infected with Streptococcus iniae showed the most significant increases in RbCC1 expression compared to the control. In the case of RSIV infection, the RbCC1 mRNA expression was markedly up-regulated in the liver. In this study, recombinant RbCC1 (approximately 53 kDa) was produced using an Escherichia coli expression system followed by purification. Subsequently, the addition of purified rRbCC1 was examined to investigate the impact on the proliferative and chemotactic activity on kidney leukocytes from rock bream. The results demonstrated that the rRbCC1 induces significant biological activity on kidney leukocyte proliferation and attraction at concentrations in the range of 10-300 μg/mL and suggests that rRbCC1 could be utilized as an immune-stimulant and/or molecular adjuvant to enhance the immune effects of vaccines.

Dissecting trafficking and signaling of atypical chemokine receptors

Atypical chemokine receptors are a distinct subset of chemokine receptors able to modulate immune responses by acting as chemokine decoy/scavengers or transporters. Intracellular trafficking properties sustained by Gαi-independent signaling have emerged as a major determinant of their biological properties, which support continuous uptake, transport, and/or concentration, of the ligands. Here, we are providing methods to study both trafficking and signaling of this class of chemokine receptors focusing on the atypical chemokine receptor D6 that degrades inflammatory CC chemokines.

Effects of small intestinal submucosa (SIS) on the murine innate immune microenvironment induced by heat-killed Staphylococcus aureus

The use of biological scaffold materials for wound healing and tissue remodeling has profoundly impacted regenerative medicine and tissue engineering. The porcine-derived small intestinal submucosa (SIS) is a licensed bioscaffold material regularly used in wound and tissue repair, often in contaminated surgical fields. Complications and failures due to infection of this biomaterial have therefore been a major concern and challenge. SIS can be colonized and infected by wound-associated bacteria, particularly Staphylococcus aureus. In order to address this concern and develop novel intervention strategies, the immune microenvironment orchestrated by the combined action of S. aureus and SIS should be critically evaluated. Since the outcome of tissue remodeling is largely controlled by the local immune microenvironment, we assessed the innate immune profile in terms of cytokine/chemokine microenvironment and inflammasome-responsive genes. BALB/c mice were injected intra-peritoneally with heat-killed S. aureus in the presence or absence of SIS. Analyses of cytokines, chemokines and microarray profiling of inflammasome-related genes were done using peritoneal lavages collected 24 hours after injection. Results showed that unlike SIS, the S. aureus-SIS interactome was characterized by a Th1-biased immune profile with increased expressions of IFN-γ, IL-12 and decreased expressions of IL-4, IL-13, IL-33 and IL-6. Such modulation of the Th1/Th2 axis can greatly facilitate graft rejections. The S. aureus-SIS exposure also augmented the expressions of pro-inflammatory cytokines like IL-1β, Tnf-α, CD30L, Eotaxin and Fractalkine. This heightened inflammatory response caused by S. aureus contamination could enormously affect the biocompatibility of SIS. However, the mRNA expressions of many inflammasome-related genes like Nlrp3, Aim2, Card6 and Pycard were down-regulated by heat-killed S. aureus with or without SIS. In summary, our study explored the innate immune microenvironment induced by the combined exposure of SIS and S. aureus. These results have practical implications in developing strategies to contain infection and promote successful tissue repair.

Enhanced production of CCL18 by tolerogenic dendritic cells is associated with inhibition of allergic airway reactivity

BACKGROUND

IL-10-treated dendritic cells (DCs) have been shown to inhibit T-cell responses through induction of anergy and regulatory T cells in various model systems, including allergic inflammation, but the factors being involved in this inhibition are still unclear.

OBJECTIVE

This study set out to analyze such factors produced or induced by IL-10-treated DCs by using gene expression profiling and to explore their function.

METHODS

CD4(+) T cells from allergic donors were stimulated with autologous monocyte-derived allergen-pulsed mature DCs or IL-10-treated DCs. After 24 hours, the transcriptional profile was analyzed by using Affymetrix technology. Results were validated by using quantitative real-time PCR, protein expression, and functional in vitro and in vivo studies.

RESULTS

In CD4(+) T-cell/IL-10-treated DC cocultures the expression of several known genes, such as IL13, IL5 and OX40, was suppressed. Interestingly, there was only one factor that was strongly upregulated: the DC-derived chemokine CCL18. In vitro addition of CCL18 to cocultures of CD4(+) T cells and allergen-pulsed DCs resulted in a similar inhibition of T(H)2 cytokine production as induced by allergen-pulsed IL-10-treated DCs without exogenous CCL18, whereas T(H)1 cytokine production, IL-10 production, and proliferation were not affected. Furthermore, in a humanized mouse model of allergy using PBMC-engrafted NOD-scid-γc(-/-) mice, CCL18, but not another T(H)2-associated chemokine, CCL17, inhibited airway reactivity and lung inflammation. Chemotaxis assays revealed that CCL18 preferentially attracted regulatory T cells and, less efficiently, T(H)2 cells.

CONCLUSION

These data demonstrate that CCL18 might represent a molecule of significant importance in immunoregulation and might be a therapeutic target in patients with allergic airway diseases.

Cloning, expression and characterization of CCL21 and CCL25 chemokines in zebrafish

Chemokines are a large group of proteins implicated in migration, activation, and differentiation of leukocytes. They are well-surveyed in mammals, but less is known in lower vertebrates about their spatiotemporal expressions and functions. From an evolutionary point of view, comparative analyses may provide some fundamental insights into these molecules. In mammals, CCL21 and CCL25 are crucial for thymocyte homing. Herein, we identified and cloned the zebrafish orthologues of CCL21 and CCL25, and analyzed their expression in embryos and adult fish by in situ hybridization. We found that CCL21 was expressed in the craniofacial region, pharynx, and blood vessels in embryos. In adult fish, CCL21 transcripts were located in the kidney, spinal cord, and blood cells. In contrast, expression of CCL25 was only detected in the thymus primordia in embryos. In adult fish, transcripts of CCL25 were maintained in the thymus, and they were also found in the brain and oocytes. Furthermore, we performed an antisense oligonucleotide experiment to evaluate the biological function of CCL25. Results showed that the recruitment of thymocytes was impeded by morpholino-mediated knockdown of CCL25, suggesting that CCL25 is essential for colonization of T-cells in the thymus in early development. Together, our results demonstrate the basic profiles of two CCL chemokines in zebrafish. The tissue-specific expression patterns may pave the way for further genetic dissection in this model organism.

A role for microRNA-155 modulation in the anti-HIV-1 effects of Toll-like receptor 3 stimulation in macrophages

HIV-1 infection of macrophages plays a key role in viral pathogenesis and progression to AIDS. Polyinosine-polycytidylic acid (poly(I:C); a synthetic analog of dsRNA) and bacterial lipopolysaccharide (LPS), the ligands for Toll-like receptors (TLR) TLR3 and TLR4, respectively, are known to decrease HIV-1 infection in monocyte-derived macrophages (MDMs), but the mechanism(s) are incompletely understood. We found that poly(I:C)- and LPS-stimulation of MDMs abrogated infection by CCR5-using, macrophage-tropic HIV-1, and by vesicular stomatitis virus glycoprotein-pseudotyped HIV-1 virions, while TLR2, TLR7 or TLR9 agonists only partially reduced infection to varying extent. Suppression of infection, or lack thereof, did not correlate with differential effects on CD4 or CCR5 expression, type I interferon induction, or production of pro-inflammatory cytokines or β-chemokines. Integrated pro-viruses were readily detected in unstimulated, TLR7- and TLR9-stimulated cells, but not in TLR3- or TLR4-stimulated MDMs, suggesting the alteration of post-entry, pre-integration event(s). Using microarray analysis and quantitative reverse transcription (RT)-PCR, we found increased microRNA (miR)-155 levels in MDMs upon TLR3/4- but not TLR7-stimulation, and a miR-155 specific inhibitor (but not a scrambled control) partially restored infectivity in poly(I:C)-stimulated MDMs. Ectopic miR-155 expression remarkably diminished HIV-1 infection in primary MDMs and cell lines. Furthermore, poly(I:C)-stimulation and ectopic miR-155 expression did not alter detection of early viral RT products, but both resulted in an accumulation of late RT products and in undetectable or extremely low levels of integrated pro-viruses and 2-LTR circles. Reduced mRNA and protein levels of several HIV-1 dependency factors involved in trafficking and/or nuclear import of pre-integration complexes (ADAM10, TNPO3, Nup153, LEDGF/p75) were found in poly(I:C)-stimulated and miR-155-transfected MDMs, and a reporter assay suggested they are authentic miR-155 targets. Our findings provide evidence that miR-155 exerts an anti-HIV-1 effect by targeting several HIV-1 dependency factors involved in post-entry, pre-integration events, leading to severely diminished HIV-1 infection.

A novel highly potent therapeutic antibody neutralizes multiple human chemokines and mimics viral immune modulation

Chemokines play a key role in leukocyte recruitment during inflammation and are implicated in the pathogenesis of a number of autoimmune diseases. As such, inhibiting chemokine signaling has been of keen interest for the development of therapeutic agents. This endeavor, however, has been hampered due to complexities in the chemokine system. Many chemokines have been shown to signal through multiple receptors and, conversely, most chemokine receptors bind to more than one chemokine. One approach to overcoming this complexity is to develop a single therapeutic agent that binds and inactivates multiple chemokines, similar to an immune evasion strategy utilized by a number of viruses. Here, we describe the development and characterization of a novel therapeutic antibody that targets a subset of human CC chemokines, specifically CCL3, CCL4, and CCL5, involved in chronic inflammatory diseases. Using a sequential immunization approach, followed by humanization and phage display affinity maturation, a therapeutic antibody was developed that displays high binding affinity towards the three targeted chemokines. In vitro, this antibody potently inhibits chemotaxis and chemokine-mediated signaling through CCR1 and CCR5, primary chemokine receptors for the targeted chemokines. Furthermore, we have demonstrated in vivo efficacy of the antibody in a SCID-hu mouse model of skin leukocyte migration, thus confirming its potential as a novel therapeutic chemokine antagonist. We anticipate that this antibody will have broad therapeutic utility in the treatment of a number of autoimmune diseases due to its ability to simultaneously neutralize multiple chemokines implicated in disease pathogenesis.

Innate defense regulator peptide synergizes with CpG ODN for enhanced innate intestinal immune responses in neonate piglets

The in vivo immunoadjuvant effects of the combination of CpG oligodeoxynucleotide (CpG ODN) and innate defense-regulator peptides (IDRs) have been studied in mice. However, little is known about the efficacy of these molecules in stimulating the innate intestinal immune system in neonatal piglets. In this study, we observed that intranasal (IN) administration of CpG-IDR (peptide HH2 (VQLRIRVAVIRA)) complex significantly increased intestinal mRNA expression of Th1 cytokines, CC chemokines and CXC chemokines when compared to HH2 and CpG ODN alone. Also an obvious cellular infiltration was observed in the intestine of CpG-HH2-treated neonatal piglets, which was associated with increased protection against Enterotoxigenic Escherichia coli (ETEC). Moreover, we showed that pro-inflammatory cytokine TNF-α was inhibited when CpG ODN combined with HH2. This was the first report that deciphered the role played by CpG-HH2 complex in the intestine of neonatal piglets. This work clearly demonstrated that efficiency of the IN route inducing intestinal responses in neonatal piglets might be taken into consideration for further vaccine development against neonatal intestinal diseases.

Identification of a cobia (Rachycentron canadum) CC chemokine gene and its involvement in the inflammatory response

The chemokines regulate immune cell migration under inflammatory and physiological conditions. We investigated a CC chemokine gene (RcCC1) from cobia (Rachycentron canadum). The full-length RcCC1 cDNA is comprised 673 nucleotides and encodes a four-cysteine arrangement 99-amino-acid protein typical of known CC chemokines. The genomic DNA of RcCC1 consists of three exons and two introns. Phylogenetic analysis showed that RcCC1 was closest to the MIP group of CC chemokines. Quantitative real-time RT-PCR (qRT-PCR) analysis revealed RcCC1 was constitutively expressed in all tissues examined, with relative strong expression in gill, blood, kidney, spleen, and head kidney. The RcCC1 transcripts in the head kidney, spleen, and liver were quickly up-regulated after stimulation with formalin-inactivated Vibrio carchariae (bacterial vaccine) or polyriboinosinic polyribocytidylic acid (poly I:C). These results indicate RcCC1 not only plays a role in homeostasis, but also may be involved in inflammatory responses to bacterial and viral infection.

Atlantic cod (Gadus morhua) CC chemokines: Diversity and expression analysis

Chemokines are a large, diverse group of small cytokines that can be classified into several families, including the CC chemokines that are characterized by two adjacent cysteines near their amino terminus. CC chemokines play a pivotal role in host defense mechanisms by inducing leukocyte chemotaxis under physiological and inflammatory conditions. Analysis of CC chemokines from teleost fishes indicates that the number of CC chemokine genes and their tissue expression patterns vary largely in this group of vertebrates. Here we describe 32 distinct CC chemokine sequences from Atlantic cod (Gadus morhua) identified by analysis of approximately 206,000 ESTs. Phylogenetic analysis of Atlantic cod CC chemokines placed these sequences in seven clusters, most likely resulting from species-specific gene duplications, and two unique sequences; 12 of these CC chemokines, including at least one member of each cluster, were analyzed by QPCR using four immune-related tissues (head kidney, liver, spleen and blood) obtained from unstimulated, polyriboinosinic polyribocytidylic acid (pIC)-stimulated and formalin-killed atypical Aeromonas salmonicida-stimulated individuals. EST abundance and QPCR analysis indicate that the expression of closely related CC chemokines GmSCYA101 and GmSCYA102, GmSCYA108 and GmSCYA109 or GmSCYA122 and GmSCYA124 can be highly tissue-specific despite substantial sequence identity. Stimulation with the viral mimic pIC or formalin-killed atypical A. salmonicida resulted in increased expression of most of the CC chemokines, indicating that they can be regarded as either inducible (inflammatory) or dual-function rather than constitutive (homeostatic). Tissue specificity, and the level of induction, varied broadly; for example, GmSCYA123 was at least 4-fold up-regulated by both inducers in all tissues analyzed, whereas pIC increased the expression of GmSCYA124 in liver over 1500 times.

Retinoid X receptor alpha controls innate inflammatory responses through the up-regulation of chemokine expression

The retinoid X receptor alpha (RXRalpha) plays a central role in the regulation of many intracellular receptor signaling pathways and can mediate ligand-dependent transcription by forming homodimers or heterodimers with other nuclear receptors. Although several members of the nuclear hormone receptor superfamily have emerged as important regulators of macrophage gene expression, the existence in vivo of an RXR signaling pathway in macrophages has not been established. Here, we provide evidence that RXRalpha regulates the transcription of the chemokines Ccl6 and Ccl9 in macrophages independently of heterodimeric partners. Mice lacking RXRalpha in myeloid cells exhibit reduced levels of CCL6 and CCL9, impaired recruitment of leukocytes to sites of inflammation, and lower susceptibility to sepsis. These studies demonstrate that macrophage RXRalpha plays key roles in the regulation of innate immunity and represents a potential target for immunotherapy of sepsis.

Evidences of the cooperative role of the chemokines CCL3, CCL4 and CCL5 and its receptors CCR1+ and CCR5+ in RANKL+ cell migration throughout experimental periodontitis in mice

Periodontal disease (PD) is characterized by the inflammatory bone resorption in response to the bacterial challenge, in a host response that involves a series of chemokines supposed to control cell influx into periodontal tissues and determine disease outcome. In this study, we investigated the role of chemokines and its receptors in the immunoregulation of experimental PD in mice. Aggregatibacter actinomycetemcomitans-infected C57Bl/6 (WT) mice developed an intense inflammatory reaction and severe alveolar bone resorption, associated with a high expression of CCL3 and the migration of CCR5+, CCR1+ and RANKL+ cells to periodontal tissues. However, CCL3KO-infected mice developed a similar disease phenotype than WT strain, characterized by the similar expression of cytokines (TNF-alpha, IFN-gamma and IL-10), osteoclastogenic factors (RANKL and OPG) and MMPs (MMP-1, MMP-2, MMP-3, TIMP-1 and TIMP-3), and similar patterns of CCR1+, CCR5+ and RANKL+ cell migration. The apparent lack of function for CCL3 is possible due the relative redundancy of chemokine system, since chemokines such as CCL4 and CCL5, which share the receptors CCR1 and CCR5 with CCL3, present a similar kinetics of expression than CCL3. Accordingly, CCL4 and CCL5 kinetics of expression after experimental periodontal infection remain unaltered regardless the presence/absence of CCL3. Conversely, the individual absence of CCR1 and CCR5 resulted in a decrease of leukocyte infiltration and alveolar bone loss. When CCR1 and CCR5 were simultaneously inhibited by met-RANTES treatment a significantly more effective attenuation of periodontitis progression was verified, associated with lower values of bone loss and decreased counts of leukocytes in periodontal tissues. Our results suggest that the absence of CCL3 does not affect the development of experimental PD in mice, probably due to the presence of homologous chemokines CCL4 and CCL5 that overcome the absence of this chemokine. In addition, our data demonstrate that the absence of chemokine receptors CCR1+ and CCR5+ attenuate of inflammatory bone resorption. Finally, our data shows data the simultaneous blockade of CCR1 and CCR5 with MetRANTEs presents a more pronounced effect in the arrest of disease progression, demonstrating the cooperative role of such receptors in the inflammatory bone resorption process throughout experimental PD.

Differential regulation of eotaxin-1/CCL11 and eotaxin-3/CCL26 production by the TNF-alpha and IL-4 stimulated human lung fibroblast

Allergic asthma and allergic dermatitis are chronic inflammatory diseases and are characterized by an accumulation of eosinophils at sites of inflammation. Eotaxin-1/CCL11 and eotaxin-3/CCL26 are members of the CC chemokine family, which are known to be potent chemoattractants for eosinophils. We observed that a human lung fibroblast, HFL-1 produces eotaxin-1 and -3 in response to TNF-alpha plus IL-4 stimulation, accompanied with NF-kappaB and STAT6 activation. We explored which signaling pathways are operative in the production of eotaxin-1 and -3 using several inhibitors. Eotaxin-1/CCL11 production was inhibited by a p38 mitogen-activated protein kinase (MAPK) inhibitor, SB203580, but not by the MEK (MAPK/ERK kinase) inhibitors, PD98059 and U0126. In contrast, eotaxin-3/CCL26 production was inhibited similarly by PD98059 as well as U0126 and SB203580. In addition, two proteasome inhibitors, N-acetyl-leucyl-leucyl-norleucinal (ALLN) and bortezomib with significant inhibitory activity on NF-kappaB activation, inhibited eotaxin-1/CCL11 production with IC50 8 microM for ALLN and IC50 16 nM for bortezomib. In contrast, eotaxin-3/CCL26 production was not inhibited significantly up to 10 microM of ALLN (IC50 16 microM) and up to 10 nM of bortezomib (IC50 11 nM), giving inhibition of eotaxin-3/CCL26 less sensitive than eotaxin-1/CCL11 production by the proteasome inhibitors. Synergistic inhibition was observed among lower doses of SB203580 and proteasome inhibitors, particularly in the eotaxin-1/CCL11 production. No such prominent synergism was found on the eotaxin-3/CCL26 production. The suppression of eotaxin family production by these inhibitors may be efficacious against allergic diseases.

Plasmids encoding the mucosal chemokines CCL27 and CCL28 are effective adjuvants in eliciting antigen-specific immunity in vivo

A hurdle facing DNA vaccine development is the ability to generate strong immune responses systemically and at local immune sites. We report a novel systemically administered DNA vaccination strategy using intramuscular codelivery of CCL27 or CCL28, which elicited elevated peripheral IFN-gamma and antigen-specific IgG while driving antigen-specific T-cell secretion of cytokine and antibody production in the gut-associated lymphoid tissue and lung. This strategy resulted in induction of long-lived antibody responses that neutralized influenza A/PR8/34 and protected mice from morbidity and mortality associated with a lethal intranasal viral challenge. This is the first example of the use of CCL27 and CCL28 chemokines as adjuvants to influence a DNA vaccine strategy, suggesting further examination of this approach for manipulation of vaccine-induced immunity impacting both quality and phenotype of responses.

Mycobacterium tuberculosis-induced expression of Leukotactin-1 is mediated by the PI3-K/PDK1/Akt signaling pathway

Chemokines function in the migration of circulating leukocytes to regions of inflammation, and have been implicated in chronic inflammatory conditions including mycobacterial infection. We investigated whether Leukotactin-1 (Lkn-1), a novel member of the CC-chemokines, is involved in the immune response of macrophages against Mycobacterium tuberculosis (MTB). In PMA-differentiated THP-1 cells, MTB infection increased mRNA expression of Lkn-1 in a dose-dependent manner. Lkn-1 induction peaked 12 h after infection, then declined gradually and returned to its basal level at 72 h. Secretion of Lkn-1 was elevated by MTB infection. The increase in expression and secretion of Lkn-1 caused by MTB was reduced in cells treated with inhibitors of phosphatidylinositol 3-kinase (PI3-K), 3-phosphoinositide-dependent kinase 1 (PDK1) and Akt. MTB-induced Akt phosphorylation was blocked by treatment with a PI3-K inhibitor or a PDK1 inhibitor, implying that PI3-K, PDK1, and Akt are associated with the signaling pathway that up-regulates Lkn-1 in response to MTB. These results suggest that Lkn-1 is novel member of the group of chemokines that is released by macrophages infected with MTB.

Autocrine production of beta-chemokines protects CMV-Specific CD4 T cells from HIV infection

Induction of a functional subset of HIV-specific CD4⁺ T cells that is resistant to HIV infection could enhance immune protection and decrease the rate of HIV disease progression. CMV-specific CD4⁺ T cells, which are less frequently infected than HIV-specific CD4⁺ T cells, are a model for such an effect. To determine the mechanism of this protection, we compared the functional response of HIV gag-specific and CMV pp65-specific CD4⁺ T cells in individuals co-infected with CMV and HIV. We found that CMV-specific CD4⁺ T cells rapidly up-regulated production of MIP-1α and MIP-1β mRNA, resulting in a rapid increase in production of MIP-1α and MIP-1β after cognate antigen stimulation. Production of β-chemokines was associated with maturational phenotype and was rarely seen in HIV-specific CD4⁺ T cells. To test whether production of β-chemokines by CD4⁺ T cells lowers their susceptibility to HIV infection, we measured cell-associated Gag DNA to assess the in vivo infection history of CMV-specific CD4⁺ T cells. We found that CMV-specific CD4⁺ T cells which produced MIP-1β contained 10 times less Gag DNA than did those which failed to produce MIP-1β. These data suggest that CD4⁺ T cells which produce MIP-1α and MIP-1β bind these chemokines in an autocrine fashion which decreases the risk of in vivo HIV infection.

HIV infection results in a significant loss of CD4⁺ T cells, particularly HIV-specific CD4⁺ T cells. In contrast to this, CMV-specific CD4⁺ T cells persist in large numbers, even in individuals with AIDS. We compared the functional profile of HIV-specific and CMV-specific CD4⁺ T cells and found that unlike HIV-specific CD4⁺ T cells, CMV-specific CD4⁺ T cells rapidly produce MIP-1β when stimulated with cognate antigen. CMV specific CD4⁺ T cells also produce another β chemokine when stimulated with cognate antigen, MIP-1α. Addition of both of these chemokines to in vitro incubations protects CD4⁺ T cells from HIV infection. To determine if the production of these two chemokines could protect the CD4⁺ T cells that produce them in vivo, we analyzed peripheral blood cells from HIV infected individuals and separated CMV-specific CD4⁺ T cells that produced MIP-1β from CMV-specific CD4⁺ T cells that did not. We found that cells that produced MIP-1β were less frequently infected with HIV than those that did not produce MIP-1β. These data, and recent advances in vaccine design, suggest that it may be possible to design a vaccine in which vaccine-induced HIV-specific CD4⁺ T cells are less susceptible to infection than those usually produced during HIV infection.

Immune effects observed after the injection of plasmids coding for rainbow trout (Oncorhynchus mykiss) CK5B, CK6 and CK7A chemokines demonstrate their immunomodulatory capacity and reveal CK6 as a major interferon inducer

In the current study, we have determined the immune effects of the intramuscular injection of eukaryotic expression plasmids coding for rainbow trout (Oncorhynchus mykiss) CK5B, CK6 or CK7A CC chemokines (pCK5B, pCK6 and pCK7A) as a first step towards the establishment of their biological role. We have studied the levels of expression of several immune genes in the spleen and head kidney by real-time PCR in comparison to the levels observed in animals injected with the empty plasmid. Concerning the levels of expression of these CC chemokines and the CXC chemokine, interleukin 8 (IL-8), each plasmid induced up-regulation on expression levels of its coded chemokine in the head kidney and spleen, but also affected the expression of other chemokines. Both pCK6 and pCK7A induced the expression of the other two CC chemokines, while pCK5B induced CK7A but not CK6. Both pCK5B and pCK7A induced IL-8 as well. pCK6 was the only plasmid that induced IL-1beta in the head kidney, whereas in the spleen, this occurred only with pCK5B. Different effects on the head kidney and spleen were also visible for tumour necrosis factor alpha (TNF-alpha), since the three plasmids induced this cytokine in the head kidney, but only pCK5B and pCK6 in the spleen. Concerning the effects on type I interferon (IFN), again pCK6 induced the strongest enhancement in the head kidney, while in the spleen it was pCK5B. However, the levels of expression of the Mx gene, know to be induced by type I IFN correlated with the CK6-induced IFN levels in the head kidney, but not with the CK5B-induced IFN in head kidney or spleen, suggesting an inhibition of Mx mRNA levels independent of IFN due to CK5B. The clear effect of pCK6 on the levels of expression of IFN-gamma and its strong effects on type I IFN, in contrast with its recent adscription to the CCL17/22 group linked to Th2 responses, were verified by studying the in vitro effects of recombinant CK6 on head kidney leukocytes. Again in this case, recombinant CK6 strongly induced type I IFN, Mx and IFN-gamma to a lesser extent, revealing CK6 as a potent IFN inducer in contrast to its mammalian homologues. Finally, effects on major histocompatibility complex (MHC)-IIalpha, CD4 and CD8alpha expression demonstrate that the three chemokines are able to mobilize antigen-presenting cells, CD4(+) and CD8(+) lymphocytes.

Thioredoxin reduces C-C chemokine-induced chemotaxis of human eosinophils

BACKGROUND

Human thioredoxin (TRX) is one of redox-active proteins that regulate reactive oxidative metabolisms. In recent study, we found that serum levels of TRX were elevated in asthmatic patients with exacerbation; however, few details are known about the physiological role of TRX in allergic inflammation, involving eosinophil infiltration.

OBJECTIVE

In the present study, we examined whether TRX modulated C-C chemokine-induced chemotaxis of human eosinophils.

METHODS

Eosinophils were isolated from subjects with mild eosinophilia by modified CD16 negative selection. After incubation with or without recombinant TRX, chemotaxis of human eosinophils was measured using Boyden chamber.

RESULTS

Preincubation with TRX suppressed eotaxin- and regulated on activation, normal T-cell expressed and secreted (RANTES)-induced chemotaxis of eosinophils. Although, TRX had no effect on the expression of C-C chemokine receptor 3, which is a receptor of eotaxin and RANTES, we demonstrated that the activation of extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinases, which play an important role in eosinophil migration, was attenuated by the treatment with TRX.

CONCLUSION

Our results suggest that the elicited TRX is beneficial to reduce allergic inflammation through negative regulation of eosinophil functions and has potential in the treatment of allergic diseases, such as asthma.

Settling the thymus: immigration requirements

Thymus settling by precursor cells is essential for the production of T cells, yet the immigration requirements are poorly defined. P-selectin and CC chemokine receptor-9 (CCR9) are involved, and settling is favored when existing residents have moved on. A new study strengthens the correlation between niche emptying and the induction of thymic P-selectin and CCR9 ligand, and provides evidence for feedback from the periphery to thymic P-selectin expression via sphingosine-1-phosphate.

Potential roles of a special CD8 alpha alpha+ cell population and CC chemokine thymus-expressed chemokine in ovulation related inflammation

It is well known that ovulation may be an inflammatory process. However, it remains elusive how immune cells participate in this process. We have identified a novel CD8alpha alpha(+) population, which resembles tissue dendritic cells, in the theca of antral follicles. We further observed a dramatic influx of the CD8alpha alpha(+) cells into the ovulating follicles. This CD8alpha alpha(+) population was absent in the ovary of estradiol-induced anovulatory C31F(1) mice and subfertile athymic nude mice. Expression of a CC chemokine thymus-expressed chemokine (TECK) has previously been found in the ovary; we further demonstrated that TECK attracted CD8alpha alpha(+) cells into the ovary. Anti-TECK Ab, elicited in the female mice by active immunization, depleted the ovarian CD8alpha alpha(+) cells in vivo. Mice with a high titer of TECK Ab failed to ovulate after superovulation induction. More importantly, the immunized mice had greatly reduced fertility, which was positively correlated with the Ab titers. Ovarian TECK expression was normal in anovulatory C31F(1) mice, suggesting that infertility in the immunized mice is due to a block of CD8alpha alpha(+) cell migration. Finally, the origin of ovarian CD8alpha alpha(+) cells was explored. Upon being transferred, thymic CD8alpha(+) cells were able to home to the theca of follicles in the recipients. Thus, ovarian CD8alpha alpha(+) cells, which participate in the ovulation-related inflammation, may originate in the thymus.

In vivo modulation of the rainbow trout (Oncorhynchus mykiss) immune response by the human alpha defensin 1, HNP1

Recent studies have demonstrated that the synthetic human defensin-alpha1, also designated as human neutrophil peptide 1 (HNP1), not only has in vitro antiviral activity against viral hemorrhagic septicemia virus (VHSV), a fish rhabdovirus, but can also modulate some immune activities of rainbow trout (Oncorhynchus mykiss) head kidney leucocytes. However, none of these HNP1 properties have been analysed in vivo so far. Thus, in the current work, we have studied the in vivo immunomodulatory capacity of HNP1 on the rainbow trout immune system as a first approach to evaluate the possible use of this family of antimicrobial peptides (AMPs) to increase fish resistance by enhancing non-specific defence mechanisms. The intramuscular injection of synthetic HNP1 induced the transcript expression of genes encoding both pro-inflammatory cytokines (IL-1beta, TNF-alpha1 and specially IL-8) and CC chemokines (CK5B, CK6 and CK7A) as well as of the genes related to type I interferon (IFN) production (Mx1, Mx2, Mx3 and IFN regulatory factor 3, IRF-3) in different trout tissues (muscle, head kidney and blood). Furthermore, the chemotactic capacity of HNP1 towards trout leucocytes has been clearly revealed. All together, these results demonstrate that in vivo HNP1 is active across species and can modulate fish immune responses. Therefore, in a moment when most pathogens have developed resistance to commonly used antibiotics, natural antimicrobial peptides with inter-specific activity, such as HNP1, might prove to be useful model molecules for the development of novel therapeutic agents that exhibit both microbicidal and immunoenhancing capabilities.

Phosphoinositide-3-kinase-dependent, MyD88-independent induction of CC-type chemokines characterizes the macrophage response to Toxoplasma gondii strains with high virulence

Chemokines play an important role in inflammation and infection due to their ability to recruit cells of innate and adaptive immunity. Here we examined mouse macrophage chemokine responses during intracellular infections with high- and low-virulence Toxoplasma gondii strains. The high-virulence type I strain RH induced a large panel of CC-type chemokines, whereas responses elicited by strains PTG (type II) and M7741 (type III) were much weaker. Strikingly, the T. gondii-induced chemokine response occurred independently of signaling through the Toll-like receptor adaptor MyD88. Instead, production of chemokines during infection was heavily dependent upon phosphoinositide-3-kinase signaling pathways. Because infection with type I strains such as RH results in an uncontrolled proinflammatory cytokine response, we hypothesize that this virulence phenotype is a consequence of early strong induction of chemokines by type I, but not type II or III, Toxoplasma strains.

Tumor-associated embryonic antigen-expressing vaccines that target CCR6 elicit potent CD8+ T cell-mediated protective and therapeutic antitumor immunity

Despite its potency, the wider use of immunotherapy for B cell malignancies is hampered by the lack of well-defined tumor-specific Ags. In this study, we demonstrate that an evolutionarily conserved 37-kDa immature laminin receptor protein (OFA-iLRP), a nonimmunogenic embryonic Ag expressed by a variety of tumors, is rendered immunogenic if targeted to the APCs using the CCR6 ligands MIP3alpha/CCL20 and mDF2beta. The CCR6 targeting facilitated efficient Ag cross-presentation and induction of tumor-neutralizing CTLs. Although the Ag targeting alone, without activation of dendritic cells (DCs), is proposed to induce tolerance, and MIP3alpha does not directly activate DCs, the MIP3alpha-based vaccine efficiently induced protective and therapeutic antitumor responses. The responses were as strong as those elicited by the OFA-iLRP fusions with moieties that activated DCs and Th1-type cytokine responses, mDF2beta, or mycobacterial Hsp70 Ag. Although the same cDNA encodes the dimerized high-affinity mature 67-kDa mLRP that is expressed in normal tissues to stabilize the binding of laminin to cell surface integrins, the vaccines expressing OFA-iLRP elicited long-term protective CD8(+) T cell-mediated memory responses against syngeneic B cell lymphoma, indicating the potential application of these simple vaccines as preventive and therapeutic formulations for human use.

Memory CD8+ T cells mediate antibacterial immunity via CCL3 activation of TNF/ROI+ phagocytes

Cytolysis, interferon gamma and tumor necrosis factor (TNF) alpha secretion are major effector mechanisms of memory CD8+ T cells that are believed to be required for immunological protection in vivo. By using mutants of the intracellular bacterium Listeria monocytogenes, we found that none of these effector activities is sufficient to protect against secondary infection with wild-type (WT) bacteria. We demonstrated that CCL3 derived from reactivated memory CD8+ T cells is required for efficient killing of WT bacteria. CCL3 induces a rapid TNF-alpha secretion by innate inflammatory mononuclear phagocytic cells (MPCs), which further promotes the production of radical oxygen intermediates (ROIs) by both MPCs and neutrophils. ROI generation is the final bactericidal mechanism involved in L. monocytogenes clearance. These results therefore uncover two levels of regulation of the antibacterial secondary protective response: (a) an antigen-dependent phase in which memory CD8+ T cells are reactivated and control the activation of the innate immune system, and (b) an antigen-independent phase in which the MPCs coordinate innate immunity and promote the bactericidal effector activities. In this context, CCL3-secreting memory CD8+ T cells are able to mediate "bystander" killing of an unrelated pathogen upon antigen-specific reactivation, a mechanism that may be important for the design of therapeutic vaccines.

Bexarotene blunts malignant T-cell chemotaxis in Sezary syndrome: reduction of chemokine receptor 4-positive lymphocytes and decreased chemotaxis to thymus and activation-regulated chemokine

The malignant cells in Sezary syndrome express the skin trafficking molecules' cutaneous lymphocyte associated antigen (CLA) and chemokine receptor 4 (CCR4). High levels of the CCR4 ligand, thymus, and activation-regulated chemokine (TARC), have been reported in the blood and skin of patients. The rexinoid X-receptor specific retinoid, bexarotene, has contributed to the resolution of cutaneous disease among patients. To evaluate the effects of bexarotene on skin trafficking molecule expression and chemotaxis, peripheral blood mononuclear cells from Sezary syndrome patients and healthy controls were treated with bexarotene in vitro. CCR4 and CLA expression levels and chemotaxis in response to TARC (6.25 ng/ml) were evaluated among lymphocytes before and after treatment with bexarotene (10 microM). Flow cytometric analysis was performed to evaluate CD4, CD26, CLA, and CCR4 cell surface expression. Transwell migration assays were performed to evaluate chemotaxis to TARC. Prior to treatment, malignant cells exhibited higher CCR4 expression (45-90%) and greater than four times more chemotaxis to TARC compared with healthy controls. After treatment with bexarotene for 36-96 hr, a 28% reduction in CCR4 expression was noted (P < 0.05) among the malignant population with an associated 9% decrease in chemotaxis to TARC (P < 0.05). Our results show that bexarotene may inhibit malignant cell trafficking to the skin through an ability to suppress CCR4 expression among Sezary syndrome lymphocytes.