Eotaxin/CCL11 suppresses IL-8/CXCL8 secretion from human dermal microvascular endothelial cells

The CC chemokine eotaxin/CCL11 is known to bind to the receptor CCR3 on eosinophils and Th2-type lymphocytes. In this study, we demonstrate that CCR3 is expressed on a subpopulation of primary human dermal microvascular endothelial cells and is up-regulated by TNF-alpha. We found that incubation of human dermal microvascular endothelial cells with recombinant eotaxin/CCL11 suppresses TNF-alpha-induced production of the neutrophil-specific chemokine IL-8/CXCL8. The eotaxin/CCL11-suppressive effect on endothelial cells was not seen on IL-1beta-induced IL-8/CXCL8 release. Eotaxin/CCL11 showed no effect on TNF-alpha-induced up-regulation of growth-related oncogene-alpha or IFN-gamma-inducible protein-10, two other CXC chemokines tested, and did not affect production of the CC chemokines monocyte chemoattractant protein-1/CCL2 and RANTES/CCL5, or the adhesion molecules ICAM-1 and E-selectin. These results suggest that eotaxin/CXCL11 is not effecting a general suppression of TNF-alphaR levels or signal transduction. Suppression of IL-8/CXCL8 was abrogated in the presence of anti-CCR3 mAb, pertussis toxin, and wortmannin, indicating it was mediated by the CCR3 receptor, G(i) proteins, and phosphatidylinositol 3-kinase signaling. Eotaxin/CCL11 decreased steady state levels of IL-8/CXCL8 mRNA in TNF-alpha-stimulated cells, an effect mediated in part by an acceleration of IL-8 mRNA decay. Eotaxin/CCL11 may down-regulate production of the neutrophil chemoattractant IL-8/CXCL8 by endothelial cells in vivo, acting as a negative regulator of neutrophil recruitment. This may play an important biological role in the prevention of overzealous inflammatory responses, aiding in the resolution of acute inflammation or transition from neutrophilic to mononuclear/eosinophilic inflammation.     

IL-10 synergistically enhances GM-CSF-induced CCR1 expression in myelomonocytic cells

CC chemokine receptor 1 (CCR1) has been implicated in inflammation. The present study examined the signaling mechanisms that mediate GM-CSF/IL-10-induced synergistic CCR1 protein expression in monocytic U937 cells. GM-CSF alone markedly increased both the mRNA and protein expression of CCR1. IL-10 augmented GM-CSF-induced CCR1 protein expression with no effect on mRNA expression. PD098059 and U0126 (two MEK inhibitors), and LY294002 (a PI3K inhibitor) inhibited GM-CSF/IL-10-induced CCR1 gene and protein expression. PD098059, U0126, and LY294002 also attenuated chemotaxis of GM-CSF/IL-10-primed U937 cells in response to MIP-1alpha. Immunoblotting studies show that GM-CSF alone induced ERK2 phosphorylation; whereas, IL-10 alone induced p70(S6k) phosphorylation in U937 cells. Neither cytokine when used alone induced PKB/Akt phosphorylation. Combined GM-CSF/IL-10 treatment of U937 cells induced phosphorylation of ERK2, p70(S6k), and PKB/Akt. PD098059 and U0126 completely abrogated ERK2 phosphorylation; whereas, LY294002 completely blocked PKB/Akt and p70(S6k) phosphorylation. Our findings indicate that IL-10 may potentiate GM-CSF-induced CCR1 protein expression in U937 cells via activation of PKB/Akt and p70(S6k).     

Chemokine receptor CCR5 deficiency exacerbates cerulein-induced acute pancreatitis in mice

Acute pancreatitis (AP) is an inflammatory disease involving the production of different cytokines and chemokines and is characterized by leukocyte infiltration. Because the chemokine receptor CCR5 and its ligands [the CC chemokines CCL3/MIP-1alpha, CCL4/MIP-1beta, and CCL5/regulated upon activation, normal T cell expressed and secreted (RANTES)] regulate leukocyte chemotaxis and activation, we investigated the expression of CCR5 ligands and the role of CCR5 and its ligands in experimental AP in mice. AP was induced by hourly intraperitoneal injections of cerulein in CCR5-deficient (CCR5(-/-)) or wild-type (WT) mice. Induction of AP by cerulein resulted in an early increase of pancreatic CCL2, CCL3, and CCL4 mRNA expression, whereas CCL5 mRNA expression occurred later. CCR5(-/-) mice developed a more severe pancreatic injury than WT mice during cerulein-induced AP, as assessed by a more pronounced increase in serum amylase and lipase levels and by more severe pancreatic edema, inflammatory infiltrates (mainly neutrophils), and necrosis. CCR5(-/-) mice also exhibited increased production of CCL2/MCP-1, CCL3/MIP-1alpha, and CCL4/MIP-1beta during the course of cerulein-induced AP. In vivo simultaneous neutralization of CC chemokines with monoclonal antibodies in CCR5(-/-) mice reduced the severity of cerulein-induced AP, indicating a role of CC chemokines in exacerbating the course of AP in the absence of CCR5. Moreover, simultaneous neutralization of CCR5 ligands in WT mice also reduced the severity of cerulein-induced AP. In conclusion, lack of the chemokine receptor CCR5 exacerbates experimental cerulein-induced AP and leads to increased levels of CC chemokines and a more pronounced pancreatic inflammatory infiltrate, suggesting that CCR5 expression can modulate severity of AP.     

Chemokine receptor expression and function in CD4+ T lymphocytes with regulatory activity

We have investigated the chemokine receptor expression and migratory behavior of a new subset of nickel-specific skin-homing regulatory CD4(+) T cells (Th(IL-10)) releasing high levels of IL-10, low IFN-gamma, and undetectable IL-4. These cells inhibit in a IL-10-dependent manner the capacity of dendritic cells to activate nickel-specific Tc1 and Th1 lymphocytes. RNase protection assay and FACS analysis revealed the expression of a vast repertoire of chemokine receptors on resting Th(IL-10), including the Th1-associated CXCR3 and CCR5, and the Th2-associated CCR3, CCR4, and CCR8, the latter at higher levels compared with Th2 cells. The most active chemokines for resting Th(IL-10), in terms of calcium mobilization and in vitro migration, were in order of potency: CCL2 (monocyte chemoattractant protein-1, CCR2 ligand), CCL4 (macrophage-inflammatory protein-1beta, CCR5 ligand), CCL3 (macrophage-inflammatory protein-1alpha, CCR1/5 ligand), CCL17 (thymus and activation-regulated chemokine, CCR4 ligand), CCL1 (I-309, CCR8 ligand), CXCL12 (stromal-derived factor-1, CXCR4), and CCL11 (eotaxin, CCR3 ligand). Consistent with receptor expression down-regulation, activated Th(IL-10) exhibited a reduced or absent response to most chemokines, but retained a significant migratory capacity to I-309, monocyte chemoattractant protein-1, and thymus and activation-regulated chemokine. I-309, which was ineffective on Th1 lymphocytes, attracted more efficiently Th(IL-10) than Th2 cells. I-309 and CCR8 mRNAs were not detected in unaffected skin and were up-regulated at the skin site of nickel-allergic reaction, with an earlier expression kinetics compared with IL-10 and IL-4. Results indicate that skin-homing regulatory Th(IL-10) lymphocytes coexpress functional Th1- and Th2-associated chemokine receptors, and that CCR8/I-309-driven recruitment of both resting and activated Th(IL-10) cells may be critically involved in the regulation of Th1-mediated skin allergic disorders.     

Macrophage inflammatory protein-3 beta enhances IL-10 production by activated human peripheral blood monocytes and T cells.

We report that the addition of human macrophage inflammatory protein-3 beta (MIP-3 beta) to cultures of human PBMCs that have been activated with LPS or PHA results in a significant enhancement of IL-10 production. This effect was concentration-dependent, with optimal MIP-3 beta concentrations inducing more than a 5-fold induction of IL-10 from LPS-stimulated PBMCs and a 2- to 3-fold induction of IL-10 from PHA-stimulated PBMCs. In contrast, no significant effect on IL-10 production was observed when 6Ckine, the other reported ligand for human CCR7, or other CC chemokines such as monocyte chemoattractant protein-1, RANTES, MIP-1 alpha, and MIP-1 beta were added to LPS- or PHA-stimulated PBMCs. Similar results were observed using activated purified human peripheral blood monocytes or T cells. Addition of MIP-3 beta to nonactivated PBMCs had no effect on cytokine production. Enhancement of IL-10 production by MIP-3beta correlated with the inhibition of IL-12 p40 and TNF-alpha production by monocytes and with the impairment of IFN-gamma production by T cells, which was reversed by addition of anti-IL-10 Abs to the cultures. The ability of MIP-3 beta to augment IL-10 production correlated with CCR7 mRNA expression and stimulation of intracellular calcium mobilization in both monocytes and T cells. These data indicate that MIP-3 beta acts directly on human monocytes and T cells and suggest that this chemokine is unique among ligands binding to CC receptors due to its ability to modulate inflammatory activity via the enhanced production of the anti-inflammatory cytokine IL-10.     

Peroxisome proliferator-activated receptor-gamma activators inhibit IFN-gamma-induced expression of the T cell-active CXC chemokines IP-10, Mig, and I-TAC in human endothelial cells

Peroxisome proliferator-activated receptor-gamma (PPARgamma), a member of the nuclear hormone receptor superfamily originally shown to play an important role in adipocyte differentiation and glucose homeostasis, is now known to regulate inflammatory responses. Given the importance of endothelial cell (EC)-derived chemokines in regulating leukocyte function and trafficking, we studied the effects of PPARgamma ligands on the expression of chemokines induced in ECs by the Th1 cytokine IFN-gamma. Treatment of ECs with PPARgamma activators significantly inhibited IFN-gamma-induced mRNA and protein expression of the CXC chemokines IFN-inducible protein of 10 kDa (IP-10), monokine induced by IFN-gamma (Mig), and IFN-inducible T-cell alpha-chemoattractant (I-TAC), whereas expression of the CC chemokine monocyte chemoattractant protein-1 was not altered. PPARgamma activators decreased IFN-inducible protein of 10 kDa promoter activity and inhibited protein binding to the two NF-kappaB sites but not to the IFN-stimulated response element ISRE site. Furthermore, PPARgamma ligands inhibited the release of chemotactic activity for CXC chemokine receptor 3 (CXCR3)-transfected lymphocytes from IFN-gamma-stimulated ECs. These data suggest that anti-diabetic PPARgamma activators might attenuate the recruitment of activated T cells at sites of Th1-mediated inflammation.     

Granulocyte-macrophage colony-stimulating factor increases synthesis and expression of CR1 and CR3 by human peripheral blood neutrophils

Polymorphonuclear leukocytes (PMN) constitutively synthesize various plasma membrane proteins including CR1(3) (CD35), CR3 (or Mac-1) alpha-chain (CD11b) and MHC class I. PMN are also able to up-regulate rapidly the expression of CR1 and CR3 to the plasma membrane in response to agonists such as FMLP. To determine whether constitutive PMN translation was static or up-regulatable, PMN were cultured in the presence or absence of the cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) for 8 h. CR1, CR3 and class I proteins immunoprecipitated from lysates of 35S-methionine pulse-labeled PMN were resolved by SDS-PAGE, fluorographed and quantified by densitometry. GM-CSF-treated PMN synthesized 4.5-fold more class I protein, 3.7-fold more CR1, 2.4-fold more CD11b and 3.4-fold more CR3 beta-chain (CD18), compared with untreated control cells. Actinomycin D treatment of replicate samples of PMN decreased the amount of these proteins synthesized by each group of PMN from 30 to 90%, implying that continued translation was required for the increases in protein synthesis. Nascent CR and class I proteins were inserted into the plasma membrane of PMN, thereby supplementing the molecules already expressed on the cell surface. In addition to these longer term effects of GM-CSF, we observed its acute up-regulatory effects on PMN. GM-CSF induced a five- to 12-fold increase in the expression of CR1 and CR3 on the PMN cell surface within 30 min. These increases were both dose- and time-dependent with maximum up-regulation occurring at 25 pM and at 30 min. In contrast to the long term biosynthetic events, this rapid up-regulation was not dependent on protein synthesis but was due instead to mobilization of CR from intracellular compartments similar to those up-regulated by FMLP. These results demonstrate that PMN can respond to microenvironmental stimuli such as GM-CSF both by rapidly up-regulating and increasing translation and expression of functionally important plasma membrane proteins.     

Combinatorial model of chemokine involvement in glomerular monocyte recruitment: role of CXC chemokine receptor 2 in infiltration during nephrotoxic nephritis

A sequential model involving chemokines has been proposed for leukocyte extravasation into areas of inflammation; however, site-specific aspects remain to be elucidated. Hence, we studied the role of chemokines produced by mesangial (MC) or glomerular endothelial cells (GEC) and their receptors in glomerular recruitment of monocytes. Stimulation of MC with TNF-alpha up-regulated mRNA and protein of CC and CXC chemokines but not constitutive expression of the CX(3)C chemokine fractalkine. While growth-related activity (GRO)-alpha was immobilized to MC proteoglycans, monocyte chemotactic protein (MCP)-1 was secreted into the soluble phase. Firm adhesion and sequestration of monocytes on activated MC was supported by the GRO-alpha receptor CXCR2 and to a lesser extent by CX(3)CR, whereas the MCP-1 receptor CCR2 contributed to their transendothelial chemotaxis toward activated MC. In contrast, fractalkine mRNA and protein was induced by TNF-alpha in transformed rat GEC, and both CXCR2 and CX(3)CR mediated monocyte arrest on GEC in shear flow. The relevance of these mechanisms was confirmed in a rat nephrotoxic nephritis model where acute glomerular macrophage recruitment was profoundly inhibited by blocking CXCR2 or CCR2. In conclusion, our results epitomize a combinatorial model in which chemokines play specialized roles in driving glomerular monocyte recruitment and emphasize an important role for CXCR2 in macrophage infiltration during early phases of nephrotoxic nephritis.     

CCL7 and CXCL10 orchestrate oxidative stress-induced neutrophilic lung inflammation.

Oxidative stress from ozone (O(3)) exposure augments airway neutrophil recruitment and chemokine production. We and others have shown that severe and sudden asthma is associated with airway neutrophilia, and that O(3) oxidative stress is likely to augment neutrophilic airway inflammation in severe asthma. However, very little is known about chemokines that orchestrate oxidative stress-induced neutrophilic airway inflammation in vivo. To identify these chemokines, three groups of BALB/c mice were exposed to sham air, 0.2 ppm O(3), or 0.8 ppm O(3) for 6 h. Compared with sham air, 0.8 ppm O(3), but not 0.2 ppm O(3), induced pronounced neutrophilic airway inflammation that peaked at 18 h postexposure. The 0.8 ppm O(3) up-regulated lung mRNA of CXCL1,2,3 (mouse growth-related oncogene-alpha and macrophage-inflammatory protein-2), CXCL10 (IFN-gamma-inducible protein-10), CCL3 (macrophage-inflammatory protein-1alpha), CCL7 (monocyte chemoattractant protein-3), and CCL11 (eotaxin) at 0 h postexposure, and expression of CXCL10, CCL3, and CCL7 mRNA was sustained 18 h postexposure. O(3) increased lung protein levels of CXCL10, CCL7, and CCR3 (CCL7R). The airway epithelium was identified as a source of CCL7. The role of up-regulated chemokines was determined by administering control IgG or IgG Abs against six murine chemokines before O(3) exposure. As expected, anti-mouse growth-related oncogene-alpha inhibited neutrophil recruitment. Surprisingly, Abs to CCL7 and CXCL10 also decreased neutrophil recruitment by 63 and 72%, respectively. These findings indicate that CCL7 and CXCL10, two chemokines not previously reported to orchestrate neutrophilic inflammation, play a critical role in mediating oxidative stress-induced neutrophilic airway inflammation. These observations may have relevance in induction of neutrophilia in severe asthma.     

Differential expression and polarized secretion of CXC and CC chemokines by human intestinal epithelial cancer cell lines in response to Clostridium difficile toxin A

Intestinal epithelial cells are the initial sites of host response to Clostridium difficile infection and can play a role in signaling the influx of inflammatory cells. To further explore this role, the regulated expression and polarized secretion of CXC and CC chemokines by human intestinal epithelial cells were investigated. An expression of the CXC chemokines, including IL-8 and growth-related oncogene (GRO)-alpha, and the CC chemokine monocyte chemoattractant protein (MCP)-1 from HT-29 cells increased in the 1-6 hr following C. difficile toxin A stimulation, assessed by quantitative RT-PCR. In contrast, the expression of neutrophil activating protein-78 (ENA-78) was delayed for 18 hr. The up-regulated mRNA expression of chemokines was paralleled by the increase of protein levels. However, the expression of macrophage inflammatory protein (MIP)-1alpha, RANTES (regulated on activation normal T cells expressed and secreted), and interferon-gamma-inducible protein-10 (IP-10) was not changed in HT-29 or Caco-2 cells stimulated with toxin A. Upon stimulation of the polarized Caco-2 epithelial cells in a transwell chamber with toxin A, CXC and CC chemokines were released predominantly into the basolateral compartment. Moreover, the addition of IFN-gamma and TNF-alpha to toxin A stimulated Caco-2 cells increased the basolateral release of CC chemokine MCP-1. In contrast, IFN-gamma and TNF-alpha had no effect on the expression of the CXC chemokines IL-8 and GRO-alpha. These results suggest that a CXC and CC chemokine expression from epithelial cells infected with C. difficile may be an important factor in the mucosal inflammatory response.     

Monocyte chemoattractant protein-1 functions as a neuromodulator in dorsal root ganglia neurons

It has previously been observed that expression of chemokine monocyte chemoattractant protein-1 (MCP-1/CC chemokine ligand 2 (CCL2)) and its receptor CC chemokine receptor 2 (CCR2) is up-regulated by dorsal root ganglion (DRG) neurons in association with rodent models of neuropathic pain. MCP-1 increases the excitability of nociceptive neurons after a peripheral nerve injury, while disruption of MCP-1/CCR2 signaling blocks the development of neuropathic pain, suggesting MCP-1 signaling is responsible for heightened pain sensitivity. To define the mechanisms of MCP-1 signaling in DRG, we studied intracellular processing, release, and receptor-mediated signaling of MCP-1 in DRG neurons. We found that in a focal demyelination model of neuropathic pain both MCP-1 and CCR2 were up-regulated by the same neurons including transient receptor potential vanilloid receptor subtype 1 (TRPV1) expressing nociceptors. MCP-1 expressed by DRG neurons was packaged into large dense-core vesicles whose release could be induced from the soma by depolarization in a Ca²⁺-dependent manner. Activation of CCR2 by MCP-1 could sensitize nociceptors via transactivation of transient receptor potential channels. Our results suggest that MCP-1 and CCR2, up-regulated by sensory neurons following peripheral nerve injury, might participate in neural signal processing which contributes to sustained excitability of primary afferent neurons.     

Morphine regulates gene expression of alpha- and beta-chemokines and their receptors on astroglial cells via the opioid mu receptor

The brain is a target organ for recreational drugs and HIV-1. Epidemiological data demonstrate that opioid abuse is a risk factor for HIV-1 infection and progression to AIDS. Chemokines and their receptors have been implicated in the neuropathogenesis of HIV-1 infections. However, little is known about the effects of opioids on the expression of chemokines and their receptors (the latter also are HIV-1 coreceptors) by cells of the CNS. Herein we describe the effects of morphine on gene expression of the alpha- and beta-chemokines and their receptors by the astrocytoma cell line U87 and by primary normal human astrocyte (NHA) cultures. U87 cells treated with morphine showed significant down-regulation of IL-8 gene expression, whereas expression of the IL-8 receptor CXCR2 was reciprocally up-regulated as detected by RT-PCR. Treatment of NHAs with morphine suppressed IL-8 and macrophage-inflammatory protein-1beta gene expression, whereas expression of their receptor genes, CCR3 and CCR5, was simultaneously enhanced. These morphine-induced effects on U87 and NHA cells were reversed by the opioid mu receptor antagonist beta-funaltrexamine. Morphine also enhanced the constitutive expression of the opioid mu receptor on astroglial cells. Our results support the hypothesis that opioids play a significant role in the susceptibility of the CNS to HIV-1 infection and subsequent encephalopathy by inhibiting local production of HIV-1-protective chemokines (IL-8 and macrophage-inflammatory protein-1beta) and enhancing expression of HIV-1 entry coreceptor genes (CCR3, CCR5, and CXCR2) within the CNS. These effects of opioids appear to be mediated through the opioid mu receptor that we demonstrated on astroglial cells.     

Differential effects of leukotactin-1 and macrophage inflammatory protein-1 alpha on neutrophils mediated by CCR1

The human CC chemokine leukotactin-1 (Lkn-1) is both a strong chemoattractant for neutrophils, monocytes, and lymphocytes and a potent agonist for CCR1 and CCR3. However, human neutrophils do not migrate when the cells are stimulated with other human CC chemokines, such as human macrophage inflammatory protein-1 alpha (hMIP-1 alpha) and eotaxin, which also use the CCR1 and CCR3 as their receptors. In this report, we demonstrate that while hMIP-1 alpha induced a negligible level of calcium flux and chemotaxis, Lkn-1 produced a high level of calcium flux and chemotaxis in human neutrophils. Lkn-1 cross-desensitized hMIP-1 alpha-induced calcium flux, but hMIP-1 alpha had little effect on the Lkn-1-induced response in human neutrophils. The same pattern was observed in peritoneal neutrophils from wild-type mice, whereas neutrophils from CCR1-/- mice failed to respond to either MIP-1 alpha or Lkn-1. Scatchard analysis revealed a single class of receptor for both hMIP-1 alpha and Lkn-1 on human neutrophils with dissociation constants (Kd) of 3.2 nM and 1.1 nM, respectively. We conclude that CCR1 is a receptor mediating responses to both MIP-1 alpha and Lkn-1 on neutrophils and produces different biological responses depending on the ligand bound.     

CXC chemokine receptor 4 expression and function in human astroglioma cells

Chemokines constitute a superfamily of proteins that function as chemoattractants and activators of leukocytes. Astrocytes, the major glial cell type in the CNS, are a source of chemokines within the diseased brain. Specifically, we have shown that primary human astrocytes and human astroglioma cell lines produce the CXC chemokines IFN-gamma-inducible protein-10 and IL-8 and the CC chemokines monocyte chemoattractant protein-1 and RANTES in response to stimuli such as TNF-alpha, IL-1beta, and IFN-gamma. In this study, we investigated chemokine receptor expression and function on human astroglioma cells. Enhancement of CXC chemokine receptor 4 (CXCR4) mRNA expression was observed upon treatment with the cytokines TNF-alpha and IL-1beta. The peak of CXCR4 expression in response to TNF-alpha and IL-1beta was 8 and 4 h, respectively. CXCR4 protein expression was also enhanced upon treatment with TNF-alpha and IL-1beta (2- to 3-fold). To study the functional relevance of CXCR4 expression, stable astroglioma transfectants expressing high levels of CXCR4 were generated. Stimulation of cells with the ligand for CXCR4, stromal cell-derived factor-1alpha (SDF-1alpha), resulted in an elevation in intracellular Ca(2+) concentration and activation of the mitogen-activated protein kinase cascade, specifically, extracellular signal-regulated kinase 2 (ERK2) mitogen-activated protein kinase. Of most interest, SDF-1alpha treatment induced expression of the chemokines monocyte chemoattractant protein-1, IL-8, and IFN-gamma-inducible protein-10. SDF-1alpha-induced chemokine expression was abrogated upon inclusion of U0126, a pharmacological inhibitor of ERK1/2, indicating that the ERK signaling cascade is involved in this response. Collectively, these data suggest that CXCR4-mediated signaling pathways in astroglioma cells may be another mechanism for these cells to express chemokines involved in angiogenesis and inflammation.     

Chemokine receptor responses on T cells are achieved through regulation of both receptor expression and signaling

To address the issues of redundancy and specificity of chemokines and their receptors in lymphocyte biology, we investigated the expression of CC chemokine receptors CCR1, CCR2, CCR3, CCR5, CXCR3, and CXCR4 and responses to their ligands on memory and naive, CD4 and CD8 human T cells, both freshly isolated and after short term activation in vitro. Activation through CD3 for 3 days had the most dramatic effects on the expression of CXCR3, which was up-regulated and functional on all T cell populations including naive CD4 cells. In contrast, the effects of short term activation on expression of other chemokine receptors was modest, and expression of CCR2, CCR3, and CCR5 on CD4 cells was restricted to memory subsets. In general, patterns of chemotaxis in the resting cells and calcium responses in the activated cells corresponded to the patterns of receptor expression among T cell subsets. In contrast, the pattern of calcium signaling among subsets of freshly isolated cells did not show a simple correlation with receptor expression, so the propensity to produce a global rise in the intracellular calcium concentration differed among the various receptors within a given T cell subset and for an individual receptor depending on the cell where it was expressed. Our data suggest that individual chemokine receptors and their ligands function on T cells at different stages of T cell activation/differentiation, with CXCR3 of particular importance on newly activated cells, and demonstrate T cell subset-specific and activation state-specific responses to chemokines that are achieved by regulating receptor signaling as well as receptor expression.     

C-C chemokines in allergen-induced late-phase cutaneous responses in atopic subjects: association of eotaxin with early 6-hour eosinophils, and of eotaxin-2 and monocyte chemoattractant protein-4 with the later 24-hour tissue eosinophilia, and relationship to basophils and other C-C chemokines (monocyte chemoattractant protein-3 and RANTES).

The relationship of expression of the C-C chemokines eotaxin, eotaxin 2, RANTES, monocyte chemoattractant protein-3 (MCP-3), and MCP-4 to the kinetics of infiltrating eosinophils, basophils, and other inflammatory cells was examined in allergen-induced, late-phase allergic reactions in the skin of human atopic subjects. EG2+ eosinophils peaked at 6 h and correlated significantly with eotaxin mRNA and protein, whereas declining eosinophils at 24 h correlated significantly with eotaxin-2 and MCP-4 mRNA. In contrast, no significant correlations were observed between BB1+ basophil infiltrates, which peaked at 24 h, and expression of eotaxin, eotaxin-2, RANTES, MCP-3, and MCP-4 or elastase+ neutrophils (6-h peak), CD3+ and CD4+ T cells (24 h), and CD68+ macrophages (72 h). Furthermore, 83% of eosinophils, 40% of basophils, and 1% of CD3+ cells expressed the eotaxin receptor CCR3, while eotaxin protein was expressed by 43% of macrophages, 81% of endothelial cells, and 6% of T cells (6%). These data suggest that 1) eotaxin has a role in the early 6-h recruitment of eosinophils, while eotaxin-2 and MCP-4 appear to be involved in later 24-h infiltration of these CCR3+ cells; 2) different mechanisms may guide the early vs late eosinophilia; and 3) other chemokines and receptors may be involved in basophil accumulation of allergic tissue reactions in human skin.     

CCR2 expression correlates with prostate cancer progression

Although the primary role of chemokines and their receptors is controlling the trafficking of leukocytes during inflammatory responses, they also play pleoitropic roles in cancer development. There is emerging evidence that cancer cells produce chemokines that induce tumor cell proliferation or chemotaxis in various cancer types. We have previously reported that MCP-1 acts as a paracrine and autocrine factor for prostate cancer (PCa) growth and invasion. As the cellular effects of MCP-1 are mediated by CC chemokine receptor 2 (CCR2), we hypothesized that CCR2 may contribute PCa progression. Accordingly, we first determined CCR2 mRNA and protein expression in various cancer cell lines, including PCa and other cancer types. All cells expressed CCR2 mRNA and protein, but in PCa, more aggressive cancer cells such as C4-2B, DU145, and PC3 expressed a higher amount of CCR2 compared with the less aggressive cancer cells such as LNCaP or non-neoplastic PrEC and RWPE-1 cells. Further, we found a positive correlation between CCR2 expression and PCa progression by analyzing an ONCOMINE gene array database. We confirmed that CCR2 mRNA was highly expressed in PCa metastatic tissues compared with the localized PCa or benign prostate tissues by real-time RT-PCR. Finally, CCR2 protein expression was examined by immunohistochemical staining on tissue microarray specimens from 96 PCa patients and 31 benign tissue controls. We found that CCR2 expression correlated with Gleason score and clinical pathologic stages, whereas lower levels of CCR2 were expressed in normal prostate tissues. These results suggest that CCR2 may contribute to PCa development.