Molecular cloning and sequencing of 25 different rhesus macaque chemokine cDNAs reveals evolutionary conservation among C, CC, CXC, AND CX3C families of chemokines

siRNAs to Knock-down Antiviral Chemokine-related Genes in FRhK-4 Cells

The objective of this study was to generate small interfering RNA (siRNA) to knockdown antiviral chemokine-related genes in fetal rhesus monkey kidney (FRhK-4) cells. We generated siRNA duplexes to suppress antiviral chemokines like CXCL10 and CCL4 in FRhK-4 cells by downregulating interferon regulatory factor (IRF) 3 and IRF7. Three siRNA duplexes (si-F-IRF3-1, si-F-IRF3-2, and si-F-IRF3-3) targeting IRF3, and one siRNA duplex (si-F-IRF7) targeting IRF7 were generated. A nontarget siRNA duplex was used as the negative control. The nontarget or target siRNA duplexes (si-F-IRF3-1, si-F-IRF3-2, si-F-IRF3-3, and si-F-IRF7) were transfected into FRhK-4 cells using transfection reagents, and they were then incubated at 37°C for 6 h with 5% CO₂. After 6 h, the medium was removed, and fresh medium was added to each cell, and they were then incubated at 37°C for 48 h with 5% CO₂. The transfected FRhK-4 cells were infected with hepatitis A virus (HAV) HM-175/18f (viral titer: 10⁵ PFU/mL) and incubated at 37°C for 3 h with 5% CO₂ for HAV propagation. The expression levels of chemokines, including CXCL10 and CCL4, under the regulation of IRF3 and IRF7 in the transfected FRhK-4 cells were measured using quantitative real-time polymerase chain reaction after 3 h of HAV infection. The results indicated that CXCL10 and CCL4 expression levels were decreased in FRhK-4 cells transfected with si-F-IRF3-1, si-F-IRF3-3, or si-F-IRF7 (p < 0.05) compared to those in the negative control. These results indicate that si-F-IRF3-1 and si-F-IRF3-3, and si-F-IRF7 successfully knocked down IRF3 and IRF7 in FRhK-4 cells, respectively and suppressed antiviral chemokines. These siRNAs could be used to suppress antiviral chemokines in FRhK-4 cells.

Role of Macrophages and Related Cytokines in Kidney Disease

Inflammation is a key characteristic of kidney disease, but this immune response is two-faced. In the acute phase of kidney injury, there is an activation of the immune cells to fight against the insult, contributing to kidney repair and regeneration. However, in chronic kidney diseases (CKD), immune cells that infiltrate the kidney play a deleterious role, actively participating in disease progression, and contributing to nephron loss and fibrosis. Importantly, CKD is a chronic inflammatory disease. In early CKD stages, patients present sub-clinical inflammation, activation of immune circulating cells and therefore, anti-inflammatory strategies have been proposed as a common therapeutic target for renal diseases. Recent studies have highlighted the plasticity of immune cells and the complexity of their functions. Among immune cells, monocytes/macrophages play an important role in all steps of kidney injury. However, the phenotype characterization between human and mice immune cells showed different markers; therefore the extrapolation of experimental studies in mice could not reflect human renal diseases. Here we will review the current information about the characteristics of different macrophage phenotypes, mainly focused on macrophage-related cytokines, with special attention to the chemokine CCL18, and its murine functional homolog CCL8, and the macrophage marker CD163, and their role in kidney pathology.

CCL18 - Beyond chemotaxis

The chemokine CCL18 is constitutively expressed in human lung and serum, and is further elevated during pathologic conditions such as allergy, fibrosis and cancer, suggesting that it may participate in both homeostatic and inflammatory processes. Under steady state conditions, CCL18 has chemotactic activity, albeit modest, toward naïve T cells and as such, may be involved in the initiation of the adaptive response. Its chemotactic effect on inflammatory cells is ambiguous as it attracts both regulatory and inflammatory immune cells. CCL18 can also modulate tissue inflammation by inhibiting cell recruitment through binding to glycosaminoglycans with high affinity, thereby displacing other chemokines bound to the endothelial surface. CCL18 induces regulatory phenotype and function of immune cells through direct activation and plays a major role in fibrotic processes, particularly in the lung. Finally, CCL18 is involved in cancer cell activation and migration and also participates in immune tolerance toward cancer. Its high constitutive expression levels and its further up-regulation in many diseases, together with its moderate chemoattractant properties support the fact that this chemokine has activities beyond cell recruitment.

Macaque paneth cells express lymphoid chemokine CXCL13 and other antimicrobial peptides not previously described as expressed in intestinal crypts

CXCL13 is a constitutively expressed chemokine that controls migration of immune cells to lymphoid follicles. Previously, we found CXCL13 mRNA levels increased in rhesus macaque spleen tissues during AIDS. This led us to examine the levels and locations of CXCL13 by detailed in situ methods in cynomolgus macaque lymphoid and intestinal tissues. Our results revealed that there were distinct localization patterns of CXCL13 mRNA compared to protein in germinal centers. These patterns shifted during the course of simian immunodeficiency virus (SIV) infection, with increased mRNA expression within and around follicles during AIDS compared to uninfected or acutely infected animals. Unexpectedly, CXCL13 expression was also found in abundance in Paneth cells in crypts throughout the small intestine. Therefore, we expanded our analyses to include chemokines and antimicrobial peptides (AMPs) not previously demonstrated to be expressed by Paneth cells in intestinal tissues. We examined the expression patterns of multiple chemokines, including CCL25, as well as α-defensin 6 (DEFA6), β-defensin 2 (BDEF2), rhesus θ-defensin 1 (RTD-1), and Reg3γ in situ in intestinal tissues. Of the 10 chemokines examined, CXCL13 was unique in its expression by Paneth cells. BDEF2, RTD-1, and Reg3γ were also expressed by Paneth cells. BDEF2 and RTD-1 previously have not been shown to be expressed by Paneth cells. These findings expand our understanding of mucosal immunology, innate antimicrobial defenses, homeostatic chemokine function, and host protective mechanisms against microbial translocation.

The disulfide bond between cysteine 10 and cysteine 34 is required for CCL18 activity

Asthma is a Th2-mediated disease that involves Th2 cell and eosinophil migration into the bronchial mucosa which is dependent upon the expression of a specific set of chemokines within the lung. Among them, CCL18 seems to play a key role because of its preferential expression in the lung, and its up-regulation by Th2 cytokines. Here, we show that the optimal naïve T cell and basophil chemotaxis, and basophil histamine release induced by rhCCL18 occurred at a 100 time lower concentration with CHO-derived rhCCL18 than with E. coli-derived rhCCL18. FT-ICR mass spectrometry of the intact chemokines showed that the rhCCL18 produced by CHO cells contained the 2 disulfide bonds Cys10-Cys34 and Cys11-Cys50, in clear contrast to the rhCCL18 derived from E. coli where the Cys10-Cys34 bond was absent. We found that reduction of the Cys10-Cys34 of the CHO-derived rhCCL18 resulted in a shift of its activity, reaching the same level as the E. coli-derived rhCCL18. These results demonstrate that the Cys10-Cys34 disulfide bond is involved in the function of CCL18.

Functional characterization of the CC chemokine RANTES from Pekin duck (Anas platyrhynchos)

RANTES (Regulated upon Activation, Normal T-cell Expressed and Secreted) is a key pro-inflammatory cytokine that belongs to the CC-group of chemokines. The present study was carried out to functionally characterize the previously identified RANTES homologue in domestic duck (GenBank Accession No. AY641435). Recombinant duck RANTES was expressed in Escherichia coli-based and HEK293T cell-based systems. A tRNA supplementation strategy was required to express the protein in E. coli due to the presence of rare codons. In biological assays using HEK293T cell-expressed protein, RANTES was found to mediate chemotaxis of DT-40 chicken B cells and primary duck splenocytes at a concentration of 0.505μg/ml (0.6μM). Immunostaining of the migrated splenocytes using anti-duck CD4 and CD8 monoclonal antibodies and subsequent flow cytometric analysis showed enhanced chemotaxis of CD8+ cells. The recombinant RANTES exhibited in vitro antiviral activity by inhibiting infection of chicken embryo fibroblast cells with duck enteritis virus (DEV) at the same concentration. The effect could be neutralized by rabbit anti-duck RANTES polyclonal serum. The mechanism seems to be direct on viral particles as evidenced by the need for co-incubation of RANTES with DEV prior to the infection for antiviral activity, and also by the enhanced binding of DEV to E. coli expressed purified RANTES on ELISA-based assays. Our results show that the duck RANTES has overlapping biological properties with its mammalian orthologue, and also has possible functional cross-reactivity with chicken immune cells indicated by the chemotaxis of DT-40 cells.

Primate-specific spliced PMCHL RNAs are non-protein coding in human and macaque tissues

Background

Brain-expressed genes that were created in primate lineage represent obvious candidates to investigate molecular mechanisms that contributed to neural reorganization and emergence of new behavioural functions in Homo sapiens. PMCHL1 arose from retroposition of a pro-melanin-concentrating hormone (PMCH) antisense mRNA on the ancestral human chromosome 5p14 when platyrrhines and catarrhines diverged. Mutations before divergence of hylobatidae led to creation of new exons and finally PMCHL1 duplicated in an ancestor of hominids to generate PMCHL2 at the human chromosome 5q13. A complex pattern of spliced and unspliced PMCHL RNAs were found in human brain and testis.

Results

Several novel spliced PMCHL transcripts have been characterized in human testis and fetal brain, identifying an additional exon and novel splice sites. Sequencing of PMCHL genes in several non-human primates allowed to carry out phylogenetic analyses revealing that the initial retroposition event took place within an intron of the brain cadherin (CDH12) gene, soon after platyrrhine/catarrhine divergence, i.e. 30–35 Mya, and was concomitant with the insertion of an AluSg element. Sequence analysis of the spliced PMCHL transcripts identified only short ORFs of less than 300 bp, with low (VMCH-p8 and protein variants) or no evolutionary conservation. Western blot analyses of human and macaque tissues expressing PMCHL RNA failed to reveal any protein corresponding to VMCH-p8 and protein variants encoded by spliced transcripts.

Conclusion

Our present results improve our knowledge of the gene structure and the evolutionary history of the primate-specific chimeric PMCHL genes. These genes produce multiple spliced transcripts, bearing short, non-conserved and apparently non-translated ORFs that may function as mRNA-like non-coding RNAs.

Afferent and efferent interfaces of lymph nodes are distinguished by expression of lymphatic endothelial markers and chemokines

BACKGROUND

Lymph nodes (LNs) are important sites of connection between the sampled peripheral tissues, the many cells of the immune system, and the blood. The organization of the interface between the afferent and efferent lymphatic vasculature and LN parenchyma is incompletely understood, and obtaining a better understanding of these tissue microenvironments will contribute to an improved understanding of overall lymphatic function.

METHODS AND RESULTS

We used histologic approaches to define the distributions of cells expressing lymphatic endothelial cell (LEC) markers in LNs from healthy, simian immunodeficiency virus (SIV) infected, or Mycobacterium tuberculosis infected cynomolgus macaques. Cells at the afferent and efferent interfaces of LNs from all animals showed differential expression of LEC markers, with podoplanin, Prox-1, and VEGFR3 expressed in both microenvironments, but with LYVE-1 expressed only at the efferent interface. The chemokine CCL20 was uniquely expressed at the afferent interface by cells co-expressing podoplanin, and this expression was increased during SIV or M. tuberculosis infection. In contrast, only a small proportion of cells expressing the CCR7 ligand CCL21 co-expressed podoplanin. Treatment of model LECs with the TLR3 ligand poly(I:C) or gamma-irradiated M. tuberculosis increased production of CCL20 without altering CCL21 or LEC marker expression.

CONCLUSIONS

This study provides a comprehensive mapping of the organization of the lymphatic endothelial network entering and exiting LNs in health and in chronic infectious diseases in a nonhuman primate model. The differences we have defined between the afferent and efferent interfaces of LNs could inform the future design of vaccines and immunotherapies.

Fractalkine expression in the rhesus monkey brain during lentivirus infection and its control by 6-chloro-2',3'-dideoxyguanosine

Existing data concerning the role of the delta-chemokine fractalkine (CX3CL1) and its receptor (CX3CR1) in lentivirus-induced encephalitis are limited and controversial. We explored, by quantitative in situ hybridization and immunohistochemistry, the cell-specific changes of CX3CL1 and CX3CR1 in rhesus macaque brain during simian immunodeficiency virus (SIV) infection and antiretroviral treatment. Neuronal expression of CX3CL1 was significantly reduced in cortex and striatum of AIDS-diseased monkeys as compared with uninfected and asymptomatic SIV-infected monkeys. CX3CL1 mRNA was increased in some endothelial cells and newly induced in astrocytes and macrophages focally in areas of SIV burden and inflammatory infiltrates. In most CX3CL1-positive astrocytes and macrophages, the transcription factor NF-kappaB was translocated to the nucleus. CX3CR1 was upregulated in scattered, nodule, and giant cell-forming microglia/macrophages and mononuclear infiltrates close to CX3CL1-induced cells in the brain. Treatment of AIDS monkeys with the central nervous system-permeant 6-chloro-2',3'-dideoxyguanosine fully reversed SIV burden, productive inflammation, nuclear NF-kappaB translocation as well as focal induction of CX3CL1 in astrocytes and macrophages and downregulation in neurons. In contrast, diffuse CX3CR1-positive microgliosis and GFAP-positive astrogliosis were partially reversed by 6-chloro-2',3'-dideoxyguanosine. Thus, focally induced CX3CL1 may be a target for therapeutic intervention to limit ongoing inflammatory infiltration into brain in lentivirus infection.

Cloning, expression, and functional characterization of cynomolgus monkey (Macaca fascicularis) CC chemokine receptor 1

The CC chemokine receptor 1 (CCR1) has emerged as a relevant factor contributing to inflammatory diseases such as allergic asthma. Commonly used animal models of allergic airway inflammation, especially murine models, have certain limitations. The elaborate, nonhuman, primate models of asthma display the highest comparability with the situation in humans. These models play an important role in the understanding of the pathogenesis of asthma. To improve the understanding in cynomolgus monkey models, we identified and characterized CCR1 in this nonhuman primate. Initially, we cloned the cynomolgus monkey CCR1 (cCCR1) gene, and the sequence analysis revealed high homology at the nucleotide (92%) and amino acid (88.4%) levels with its human counterpart. Human embryonic kidney 293 cells were stably transfected with cCCR1 and used in functional assays. Among those CCR1 ligands tested, CCL14(9-74) was most potent in the induction of intracellular Ca2+ fluxes as observed for human CCR1 (hCCR1). Complete cross-desensitization could be achieved between CCL14(9-74) and CCL15. However, CCL3 could not fully abrogate the response to the potent ligand CCL14(9-74). Competition-binding studies with radiolabeled CCL3 concordantly showed that CCL14(9-74) has a higher affinity to cCCR1 than hCCL3. Moreover, differential tissue-specific expression of cCCR1 was investigated by real-time quantitative polymerase chain reaction, displaying the highest levels in spleen. This study adds basic information needed for the evaluation of the role of CCR1 in the pathophysiology of asthma using the highly relevant cynomolgus monkey model and in addition, aids in the preclinical evaluation of potential novel drugs targeting CCR1.

Cross-reactivity of anti-human chemokine receptor and anti-TNF family antibodies with common marmoset (Callithrix jacchus) leukocytes

The common marmoset (Callithrix jacchus) is a New World primate species frequently employed for immunological models of human disease. We used flow cytometry to screen a panel of new anti-human antibodies from the HLDA8 workshop to establish cross-reactivity with marmoset peripheral blood mononuclear cells. Seventy-seven antibodies were screened of which nine antibodies showed binding. Cross-reactivity of anti-human monoclonal antibodies with CC and CXC chemokine receptors CCR3, CCR6, CCR7, and CCR8 was demonstrated on untreated marmoset mononuclear cells. Stimulation of marmoset mononuclear cells with ConA and/or PMA-ionomycin resulted in an up-regulated expression of CXCR1, CXCR3, and CXCR4. The expression of TNF-family related molecules TACI and APRIL on marmoset mononuclear cells was also identified. These studies extend the range of cross-reactive antibodies to now include anti-chemokine and anti-TNF family antibodies for this important pre-clinical model species and should provide useful tools for investigation of immunological processes in marmoset monkey models.

Involvement of CC chemokine ligand 18 (CCL18) in normal and pathological processes

CC chemokine ligand 18 (CCL18) was originally discovered as pulmonary and activation-regulated chemokine (PARC), dendritic cell (DC)-chemokine 1 (DC-CK1), alternative macrophage activation-associated CC chemokine-1 (AMAC-1), and macrophage inflammatory protein-4 (MIP-4). CCL18 primarily targets lymphocytes and immature DC, although its agonistic receptor remains unknown so far. CCL18 is mainly expressed by a broad range of monocytes/macrophages and DC. A more profound understanding of the various activation programs and functional phenotypes of these producer cells might give a better insight in the proinflammatory versus anti-inflammatory role of this CC chemokine. It is interesting that CCL18 is constitutively present at high levels in human plasma and likely contributes to the physiological homing of lymphocytes and DC and to the generation of primary immune responses. Furthermore, enhanced CCL18 production has been demonstrated in several diseases, including various malignancies and inflammatory joint, lung, and skin diseases. The lack of a rodent counterpart for human CCL18 sets all hope on primate animal models to further elucidate the importance of CCL18 in vivo. This review will address these different aspects in more detail.

Characterization of a highly inducible novel CC chemokine from differentiated rainbow trout (Oncorhynchus mykiss) macrophages

A full-length cDNA clone encoding a novel trout CC chemokine was identified in expressed sequence tags generated from lipopolysaccharide (LPS)-stimulated in vitro differentiated macrophages isolated from the head kidney of the rainbow trout (Oncorhynchus mykiss). The putative 101-amino-acid protein is 38% similar to Macaca mulatta CCL4 (macrophage inflammatory protein 1beta) but is also similar to several other related mammalian CC chemokines, including human Act-2. Real-time PCR and conventional RT-PCR revealed significant up-regulation of transcript levels of the trout CCL4-like mRNA in LPS-stimulated in vitro differentiated macrophages. In unstimulated trout, CCL4-like mRNA expression was detected at different levels in all tissues tested, whereas in LPS-challenged animals (6 mg/kg), CCL4-like mRNA increased in intestine, ovary and spleen at both 24 h and 72 h post-injection. In gills, CCL4-like mRNA expression was inhibited after LPS administration. Based on the highly regulated expression pattern exhibited by the trout CCL4-like mRNA, it is likely that this chemokine plays an important regulatory role in the immune response of trout.

Cloning and Pharmacological Characterization of CXCR1 and CXCR2 fromMacaca fascicularis

Two genes with high sequence homology to human CXCR1 (hCXCR1) and CXCR2 (hCXCR2) were cloned from blood of cynomolgus monkey (Macaca fascicularis). Comparison of the expression pattern of these receptors in different species demonstrated that, like in humans, cynomolgus CXCR1 (cCXCR1) and CXCR2 (cCXCR2) are highly expressed in blood. Membranes from transfected BaF3 cells expressing cCXCR1 bind interleukin (IL)-8 with an affinity similar to hCXCR1 (Kd values, 170 +/- 87 and 103 +/- 37 pM, respectively) and show low binding affinity to Gro-alpha. Cynomolgus CXCR2 also binds hIL-8 but with somewhat higher affinity than the hCXCR2 (46 +/- 28 and 220 +/- 14 pM, respectively). Surprisingly, cCXCR2 has a reduced binding affinity to hGro-alpha (3.7 +/- 2.2 nM), a specific ligand of hCXCR2 (540 +/- 140 pM). Furthermore, the CXCR2-specific antagonist SB225002 [N-(2-hydroxy-4-nitrophenyl)-N'-(2-bromophenyl)urea] is 10-fold more potent in inhibiting IL-8 binding to hCXCR2 than to cCXCR2, suggesting that some of the observed differences in the amino acid sequences of the human and monkey receptor affect ligand binding sites or the conformation of the receptor. Both cynomolgus receptors were functionally active in inducing guanosine 5'-O-(3-thio)triphosphate exchange on membranes in response to IL-8 and Gro-alpha and in mediating chemotactic activity of recombinant BA/F3 cells in response to IL-8 and Gro-alpha. These results identify the products of the novel cynomolgus genes as functional homologs of hCXCR1 and hCXCR2.

Productive infection of dendritic cells by simian immunodeficiency virus in macaque intestinal tissues

Dendritic cells (DCs) are potent antigen-presenting cells that likely play multiple roles in human immunodeficiency virus-1 (HIV-1) and simian immunodeficiency virus (SIV) pathogenesis. This paper describes the effects of pathogenic SIV infection on the networks of DCs in rhesus macaque (Macaca mulatta) intestinal tissues. Intestinal tissues were obtained from macaques at different stages of disease following infection with the pathogenic SIV/DeltaB670 isolate. The patterns and levels of expression of SIV and DC-associated mRNAs were examined and quantitated directly in intestinal tissue sections. In situ hybridization was performed for SIV, DC-specific ICAM3-grabbing non-integrin (DC-SIGN), DC-specific lysosome-associated membrane glycoprotein (DC-LAMP), DC-specific C-type lectin 1 (DECTIN-1), CC chemokine receptor 6 (CCR6), CCR7, and macrophage inflammatory protein 3alpha (MIP-3alpha/CCL20) mRNAs and quantitative image analysis was performed to measure mRNA expression levels. To identify the cell types productively infected by SIV, simultaneous in situ hybridization and immunohistochemical staining were performed. The DC networks in macaque intestinal tissues were found to be extensive and although they generally remained intact during the course of SIV infection, there were alterations in the expression of markers for immature DCs. One alteration was an increase in the expression in intestinal submucosa of DC-SIGN, a molecule that binds to HIV-1/SIV and increases its infectivity. Concomitant with this increase, it was found that during AIDS, the population of productively infected cells included DCs, based on co-expression of DC-SIGN and DECTIN-1 mRNAs. These data indicate that SIV infection affects subpopulations of macaque intestinal DCs, including productive infection of DC-SIGN+ DCs, the consequences of which are likely to be ongoing viral propagation and decreased immunostimulatory function.

In situ study of abundant expression of proinflammatory chemokines and cytokines in pulmonary granulomas that develop in cynomolgus macaques experimentally infected with Mycobacterium tuberculosis

Tuberculosis remains a major public health problem worldwide. Chemokines and cytokines organize and direct infiltrating cells to sites of infection, and these molecules likely play crucial roles in granuloma formation and maintenance. To address this issue, we used in situ hybridization (ISH) to measure chemokine and cytokine mRNA expression levels and patterns directly in lung tissues from cynomolgus macaques (Macaca fascicularis) experimentally infected with a low dose of virulent Mycobacterium tuberculosis. We examined more than 300 granulomas and observed abundant expression of gamma interferon (IFN-gamma)-inducible chemokine mRNAs (CXCL9/monokine induced by IFN-gamma, CXCL10/IFN-gamma-inducible protein, and CXCL11/IFN-gamma-inducible T-cell alpha-chemoattractant) within solid and caseous granulomas, and there was only minimal expression in nongranulomatous regions of tissue. The mRNA expression patterns of IFN-gamma and tumor necrosis factor alpha were examined in parallel, and the results revealed that cytokine mRNA(+) cells were abundant and generally localized to the granulomas. Mycobacterial 16S rRNA expression was also measured by ISH, and the results revealed that there was localization predominantly to the granulomas and that the highest signal intensity was in caseous granulomas. We observed several granulomatous lesions with exceptionally high levels of RNA for mycobacterial 16S rRNA, IFN-gamma, and IFN-gamma-inducible chemokines, suggesting that the local presence of mycobacteria is partially responsible for the upregulation of IFN-gamma-inducible chemokines and recruitment of CXCR3(+) cells, which were also abundant in granulomatous lesions. These results suggest that expression of CXCR3 ligands and the subsequent recruitment of CXCR3(+) cells are involved in granuloma formation and maintenance.

Expression of IFN-gamma induced CXCR3 agonist chemokines and compartmentalization of CXCR3+ cells in the periphery and lymph nodes of rhesus macaques during simian immunodeficiency virus infection and acquired immunodeficiency syndrome

Dysregulation of cytokines and chemokines during human immunodeficiency virus 1 (HIV-1) and simian immunodeficiency virus (SIV) infection is thought to be critical in the progression of acquired immunodeficiency syndrome (AIDS). To evaluate the potential role of Th1-agonist chemokines in disease progression during AIDS, we assessed CXCL9/MIG and CXCL10/IP-10 expression simultaneously in the periphery and lymphoid tissues of SIV-infected animals at a single-cell level by flow cytometry. We optimized intracellular staining and analysis of CXCL9/MIG and CXCL10/IP-10 production in human leukocyte antigen (HLA)-DR+ macaque cells by flow cytometry using cross-reactive antibodies against human chemokines. We observed an upregulation of CXCL9/MIG and CXCL10/IP-10 production in both the periphery and lymph nodes of infected animals compared with naïve controls. Animals with higher viral loads had higher levels of CXCL9/MIG and CXCL10/IP-10 producing cells compared with animals with low viral loads. Analysis of cells bearing the receptor (CXCR3) for CXCL9/MIG and CXCL10/IP-10 revealed increased number of CXCR3+ cells in the lymph nodes of infected animals. Importantly, an inverse correlation (P < 0.05) between CXCL9/MIG and CXCL10/IP-10 production, both in the periphery and lymph nodes, and peripheral CD4+ T-cell numbers was observed. These findings provide further evidence that dysregulation of Th1 agonist chemokines might contribute to the ultimate immunopathology during AIDS.

The CC chemokine CCL20 and its receptor CCR6

CCL20, alternatively named liver and activation-regulated chemokine (LARC), macrophage inflammatory protein-3alpha (MIP-3alpha) or Exodus-1, is the only chemokine known to interact with CC chemokine receptor 6 (CCR6), a property shared with the antimicrobial beta-defensins. The ligand-receptor pair CCL20-CCR6 is responsible for the chemoattraction of immature dendritic cells (DC), effector/memory T-cells and B-cells and plays a role at skin and mucosal surfaces under homeostatic and inflammatory conditions, as well as in pathology, including cancer and rheumatoid arthritis. In this review, the discovery, the gene and protein structure, the in vitro biological activities, the cell and inducer specific expression and the tissue distribution of CCL20 and CCR6 are discussed.

Simian immunodeficiency virus dramatically alters expression of homeostatic chemokines and dendritic cell markers during infection in vivo

Dendritic cells (DCs) are potent antigen-presenting cells that likely play multiple roles in human immunodeficiency virus type 1 (HIV-1) pathogenesis. We used the simian immunodeficiency virus (SIV)/macaque model to study the effects of infection on homeostatic chemokine expression and DC localization directly in secondary lymphoid tissues. SIV infection altered the expression of chemokines (CCL19/MIP-3beta, CCL21/ 6Ckine, and CCL20/MIP-3alpha) and of chemokine receptors (CCR7 and CCR6) that drive DC trafficking. CCL19/MIP-3beta, CCL20/MIP-3alpha, CCR6, and CCR7 expression increased in lymph nodes during the early systemic burst of viral replication (acute infection), whereas CCL21/6Ckine expression progressively decreased throughout disease to AIDS. Parallel with the SIV-induced perturbations in chemokine expression were changes in the expression of the DC-associated markers, DC-SIGN, DC-LAMP, and DECTIN-1. During AIDS, DC-LAMP mRNA expression levels were significantly reduced in lymph nodes and spleen, and DC-SIGN levels were significantly reduced in spleen. These findings suggest that the disruption of homeostatic chemokine expression is responsible, in part, for alterations in the networks of antigen-presenting cells in lymphoid tissues, ultimately contributing to systemic immunodeficiency.