Chemokine receptor antagonists: a novel therapeutic approach in allergic diseases

The aim of this review is to give an overview of the role of chemokines, particularly ligands of the CC chemokine receptor CCR3, in allergic diseases and to show the new concept in the treatment of allergies using chemokine receptor antagonists. Allergic diseases such as allergic asthma, allergic rhinitis and atopic dermatitis are characterized by a complex interaction of different cell types and mediators. Among this, Th2 cells, mast cells, basophils and eosinophils are found in the inflamed tissue due to the attraction of chemokines. Of all the known chemokine receptors, the chemokine receptor CCR3 seems to play the major role in allergic diseases which is supported by the detection of this receptor on the cell types mentioned above. Therefore, academic and industrial research focus on compounds to block this receptor. To date, certain chemokine receptor antagonists derived from peptides and small molecules exist to block the chemokine receptor CCR3. However, the in vivo data about these compounds and the mechanisms of receptor interaction are poorly understood, as yet. For the development of additional chemokine receptor antagonists, more details about the interaction between the ligands and their receptors are required. Therefore, additional studies will lead to the identification of novel CCR3 chemokine receptor antagonists, which can be therapeutically used in allergic asthma, allergic rhinitis, and atopic dermatitis.

Soluble Expression of Recombinant Human Secondary Lymphoid Chemokine (SLC) in E. coli and Research on Its In Vitro and In Vivo Bioactivity

Secondary lymphoid tissue chemokine (SLC) is a CC chemokine that plays an important role in leukocytes homing to lymphoid tissues. The ability of SLC to co-localize both T cells and dendritic cells formed the rationale to evaluate its utility in cancer immunotherapy. The in vivo antitumor effect of murine SLC (mSLC) has been well documented, but little is known about that of human SLC (hSLC). To investigate the antitumor efficiency in vivo of hSLC, the hSLC gene was artificially synthesized and induced to express as a soluble form in Escherichia coli. After purification, the purity of the recombinant human SLC (rhSLC) protein was above 95% by SDS-PAGE analysis. The K(d) of rhSLC binding to peripheral blood lymphocytes (PBLs) was 0.2186 +/- 0.02675 microM as assessed by FACS, and the maximal chemotactic index of rhSLC was 9.49 at 100 nM as assessed by in vitro chemotaxis assay. Then genomic sequences of hSLC and mSLC, and of human CCR7 (hCCR7) and murine CCR7 (mCCR7), the receptor for SLC, were aligned. It was found that hSLC and mSLC share 70.72% identity and hCCR7 and mCCR7share 86.77% identity. Furthermore, we found that rhSLC could chemoattract murine peripheral blood mononuclear cells (PBMCs) in vitro. On the basis of these facts, immune competent mice inoculated with S180 sarcoma cells were chosen as an in vivo model. Intratumoral injections of rhSLC inhibited tumor growth and increased survival. These findings suggest that, despite its incapability to bind to either human or murine CXCR3, which is related to angiostasis, rhSLC can induce an antitumor response in vivo by another route. This report proves that rhSLC has a potent tumor-inhibition ability that makes it a promising candidate agent in cancer immunotherapy.

Differential sensitivities of pyrogenic chemokine fevers to CC chemokine receptor 5 antibodies

Macrophage inflammatory protein (MIP)-1beta and RANTES (regulated on activation, normal T-cells expressed and secreted) are members of the CC-family of chemokines. Although these two peptides are structurally and functionally related to one another, each exhibits distinct features, which allows it to independently regulate specific aspects of the host inflammatory response. They evoked intense and functionally different febrile responses when applied directly on pyrogen-sensitive cells located in the in the preoptic area of the anterior hypothalamus (POA). The present experiments were carried out to test the central role of CCR5, a functional receptor for MIP-1beta and RANTES, in the febrile responses induced by these chemokines when injected directly into the POA. The microinjection of an equimolecular dose (50 pg) of either MIP-1beta or RANTES into the POA induced a rapid onset; monophasic fever in rats that persisted for a long period. The microinjection of 2.0 microg specific neutralizing antibodies against CCR5 (anti-CCR5) into the POA fails to affect the effects on body temperature induced by MIP-1beta. However, pretreatment with the same dose of anti-CCR5 suppressed the febrile response induced by RANTES given at the same site. The microinjection of control IgG or anti-CCR5 does not affect basal temperature, when administered alone at the same hypothalamic site. The present experiments show that hypothalamic CCR5 are functionally involved in the febrile response induced by RANTES, but not by MIP-1beta. They also suggest the existence of functionally different components in the presumptive primary locus of the thermoregulatory controller, in which both chemotactic cytokines, together other mediators, could play a relevant role in the complex process of fever pathogenesis.

CCL25/CCR9 promotes the induction and function of CD103 on intestinal intraepithelial lymphocytes

The integrin CD103 and the chemokine receptor CCR9 are co-expressed on small intestinal CD8(+) intraepithelial lymphocytes (IEL), naïve murine CD8(+) T cells and by a small population of effector/memory CD8(+) T cells, indicating a potential role for CCR9 in regulating CD103 expression and function. Here, we demonstrate that CD103, in contrast to CCR9, is down-regulated on CD8(+) T cells following their activation in mesenteric lymph nodes and that effector CD8(+) T cells upon initial entry into the small intestinal epithelium are CCR9(+)CD103(-). CD103 was rapidly induced on wild-type CD8(+) T cells subsequent to their entry into the small intestinal epithelium, however, CCR9(-/-) CD8(+) T cells exhibited a significant delay in CD103 induction at this site. In addition, the CCR9 ligand, CCL25, that is constitutively expressed in the small intestinal epithelium, induced transient, dose-dependent and pertussis toxin-sensitive CD103-mediated adhesion of CD8(+) small intestinal IEL to a murine E-cadherin human Fc (mEFc) fusion protein. Together, these results demonstrate a role for CCR9/CCL25 in promoting the induction and function of CD103 on CD8(+) IEL and suggest that this chemokine receptor/chemokine pair may function to regulate lymphocyte-epithelial interactions in the small intestinal mucosa.

The role of the Th2 CC chemokine ligand CCL17 in pulmonary fibrosis

Increasing evidence suggests that the development of pulmonary fibrosis is a Th2-mediated process. We hypothesized that the CC chemokines that are associated with a Th2 profile (CCL17 and CCL22) have an important role in the development of pulmonary fibrosis. We measured CCL17 and CCL22 during the pathogenesis of bleomycin-induced pulmonary fibrosis. We found that both CCL17 and CCL22 were significantly elevated through day 20 as compared with control mice. Peak expression of CCL22 preceded the peak levels of CCL17, as measured by real-time quantitative PCR. CCR4 is the receptor for CCL17 and CCL22 therefore, to further characterize the role of CCL17 and CCL22, we measured CCR4 mRNA in lung tissue of bleomycin-treated mice by real-time quantitative PCR. CCR4 was significantly elevated in bleomycin-treated mice as compared with control mice. Immunolocalization demonstrated that CCR4 was expressed predominantly on macrophages. Neutralization of CCL17, but not CCL22, led to a reduction in pulmonary fibrosis. Immunolocalization of bleomycin-treated lung tissue and human idiopathic pulmonary fibrosis tissue specimens showed that epithelial cells expressed CCL17. These findings demonstrate a central role for Th2 chemokines and the macrophage in the pathogenesis of pulmonary fibrosis and are further support for the role of a Th2 phenotype in the pathogenesis of pulmonary fibrosis.

Increased expression of CCL20 in human inflammatory bowel disease

Inflammatory bowel disease (IBD) constituting Crohn's disease (CD) and ulcerative colitis (UC) is related to a dysregulated T cell response. CCL20 attracts memory T lymphocytes and dendritic cells. We asked whether CCL20 expression is altered in IBD. Colonic biopsies were obtained from 114 subjects with IBD, non-IBD colitis, irritable bowel syndrome, and healthy controls. CCL20 and CCR6 mRNA expression was measured by Taqman-PCR, and protein secretion from colonic explant cultures (CEC) and its regulation by TNF-alpha by ELISA. CCL20, CCR6, and Langerin were identified by immunohistochemistry and immunofluorescence. CCL20 mRNA and protein were severalfold increased in involved CD and UC but not in non-IBD colitis. TNF-alpha increased and anti-TNF-alpha decreased CCL20 release in healthy control CEC but not in involved IBD colonic specimens. CCL20 localized to follicle-associated epithelium, and CCR6 to the adjacent mantle zone of lymphoid follicles. Furthermore, abundant numbers of Langerin(+) immature dendritic cells were identified in the subepithelial space of IBD specimens. CCL20 might regulate the attraction of T lymphocytes and dendritic cells in IBD.

WHIM syndromes with different genetic anomalies are accounted for by impaired CXCR4 desensitization to CXCL12

The WHIM syndrome is a rare immunodeficiency disorder characterized by warts, hypogammaglobulinemia, infections, and myelokathexis. Dominant heterozygous mutations of the gene encoding CXCR4, a G-protein-coupled receptor with a unique ligand, CXCL12, have been associated with this pathology. We studied patients belonging to 3 different pedigrees. Two siblings inherited a CXCR4 mutation encoding a novel C-terminally truncated receptor. Two unrelated patients were found to bear a wild-type CXCR4 open reading frame. Circulating lymphocytes and neutrophils from all patients displayed similar functional alterations of CXCR4-mediated responses featured by a marked enhancement of G-protein-dependent responses. This phenomenon relies on the refractoriness of CXCR4 to be both desensitized and internalized in response to CXCL12. Therefore, the aberrant dysfunction of the CXCR4-mediated signaling constitutes a common biologic trait of WHIM syndromes with different causative genetic anomalies. Responses to other chemokines, namely CCL4, CCL5, and CCL21, were preserved, suggesting that, in clinical forms associated with a wild-type CXCR4 open reading frame, the genetic anomaly might target an effector with some degree of selectivity for the CXCL12/CXCR4 axis. We propose that the sustained CXCR4 activity in patient cells accounts for the immune-hematologic clinical manifestations and the profusion of warts characteristic of the WHIM syndrome.

Role of CCR4 ligands, CCL17 and CCL22, during Schistosoma mansoni egg-induced pulmonary granuloma formation in mice

Controversy persists pertaining to the role of CCR4 ligands, namely CCL17 (or thymus and activation regulated chemokine; TARC) and CCL22 (or macrophage-derived chemokine; MDC), in Th2-type cytokine-dominated responses in the lung. Accordingly, the present study addressed the relative role of each of these CC chemokines during an evolving pulmonary granulomatous response elicited by the intrapulmonary embolization of live Schistosoma mansoni eggs into S. mansoni-sensitized mice. CCL22 protein expression peaked at day 4, but CCL17 levels were not increased significantly at any time after egg challenge. CCR4 transcript and protein expression were highest at day 8 after egg embolization and CCR4 protein was prominently expressed in macrophages surrounding S. mansoni eggs. Systemic immunoneutralization of CCL22 from the time of egg injection into S. mansoni-sensitized mice for 8 days significantly decreased CCR4 protein expression, the eosinophil content, the overall size of the egg granuloma, and its hydroxyproline content. Whole lung levels of interferon-gamma were also significantly increased at day 8 in anti-CCL22-treated mice. The systemic immunoneutralization of CCL17 had a lesser effect on all of the granuloma parameters listed above, but this antibody treatment significantly decreased granuloma hydroxyproline content to a greater extent than the anti-CCL22 antibody treatment. In addition, the immunoneutralization of CCL17 significantly increased whole lung levels of interleukin (IL)-4, IL-5, IL-13, transforming growth factor-beta, IL-12, and tumor necrosis factor-alpha at day 8 after egg infusion. Thus, these studies demonstrate a major role for CCL22 and a lesser role for CCL17 during an evolving S. mansoni egg granuloma in the lung.

Is secondary lymphoid-organ chemokine (SLC/CCL21) much more than a constitutive chemokine?

Chemokines are a superfamily of small cytokines with activities ranging from leukocyte traffick to hematopoiesis, angiogenesis, and tissue organogenesis. Secondary lymphoid-organ chemokine (SLC/CCL21) was originally reported as a chemokine constitutively expressed by stromal cells and high endothelial venules in secondary lymphoid tissues and endothelium of afferent lymphatics, directing CCR7+ cells. More recently, others and we have demonstrated that SLC/CCL21 is up-regulated in different skin inflammatory conditions. Thereafter, this molecule is much more than a constitutive chemokine, which could play a role in effector and regulatory immune functions.

Co-localization of Macrophage Inflammatory Protein-3?? (Mip-3??) and Its Receptor, CCR6, Promotes Pancreatic Cancer Cell Invasion

PURPOSE

Macrophage inflammatory protein-3alpha (Mip-3alpha) is par t of a family of chemotactic cytokines involved in recruiting inflammatory cells throughout the body. CCR6 is a G-protein-linked, seven-transmembrane receptor that is highly specific for Mip-3alpha. The role of Mip-3alpha has been well defined in several inflammatory conditions, but its role has not been well defined in neoplastic processes. Mip-3alpha has been shown to promote pancreatic cancer cell migration, but no studies have demonstrated the effect of Mip-3alpha on pancreatic cancer cell invasion. We hypothesize that Mip-3alpha and its CCR6 receptor promote pancreatic cancer cell invasion.

MATERIALS AND METHODS

Immunohistochemical staining was per formed for Mip-3alpha and CCR6 in pancreatic cancer tissue and the human pancreatic cancer cell line PANC-1. RNA was isolated from PANC-1 cancer cells, and the presence of Mip-3alpha messenger RNA in PANC-1 cancer cells was determined by reverse transcriptase polymerase chain reaction. PANC-1 cancer cell invasion of type IV collagen was evaluated in the presence of Mip-3alpha and anti-CCR6 antibody with the use of a modified Boyden chamber invasion assay.

RESULTS

Co-localization of Mip-3alpha and its CCR6 receptor in pancreatic cancer was confirmed using immunohistochemical staining for Mip-3alpha and its CCR6 receptor and reverse transcriptase polymerase chain reaction for Mip-3alpha. Immunohistochemical staining of pancreatic cancer tissue and the PANC-1 cancer cell line showed positive staining for Mip-3alpha and its CCR6 receptor within the cancer cells. Staining was also positive for Mip-3alpha within stromal cells adjacent to the cancer cells in pancreatic cancer tissue. Reverse transcriptase polymerase chain reaction demonstrated the presence of Mip-3alpha messenger RNA within PANC-1 cancer cells. Invasion studies showed that increasing concentrations of Mip-3alpha promoted a dose-dependent increase in pancreatic cancer cell invasion of type IV collagen. The addition of 100 ng/mL of Mip-3alpha promoted a threefold increase in pancreatic cancer cell invasion over that of the control group. Anti-CCR6 antibody inhibited Mip-3alpha-stimulated PANC-1 cancer cell invasion of type IV collagen by 63%.

DISCUSSION

Co-localization of Mip-3alpha and its CCR6 receptor promotes pancreatic cancer cell invasion of type IV collagen. This finding continues to highlight the importance that inflammation plays in the progression of pancreatic cancer. As the relationship between the inflammatory and neoplastic processes involved with pancreatic cancer becomes better defined, therapies targeting the inflammatory process may help prevent pancreatic cancer invasion and metastasis.

Migration and maturation of human dendritic cells infected with Toxoplasma gondii depend on parasite strain type

Migration and maturation of human dendritic cells derived from CD34+ progenitor cells (DC) infected by Toxoplasma gondii were studied in an in vitro model. We demonstrated that infection with virulent type I strains RH and ENT or type II low virulent strains PRU and CAL induced DC migration towards MIP-3beta. However, type II strains induced a higher percentage of migrating cells than that induced by type I strains or positive controls (chemical allergen or lipopolysaccharides). Type II strains produced soluble factors responsible of the high migration whereas heat killed tachyzoites did not induced a migration higher than positive controls. We also demonstrated that infection by virulent strains and not by type II stains or heat killed tachyzoites triggers DC maturation. A soluble factor released by type II strains was responsible of the absence of DC maturation. Taken together, these results demonstrated that the interference of T. gondii in the behaviour of DC functions is related to the strain types and can be supported by secretion of soluble factors by the parasite.

Control of Salmonella dissemination in vivo by macrophage inflammatory protein (MIP)-3alpha/CCL20

While chemokines are clearly important in the generation of protective immunity, the role of individual chemokines in the control of bacterial infection is still poorly understood. In this study, we investigated the role of macrophage inflammatory protein (MIP)-3alpha/CCL20, a chemokine that attracts activated T and B lymphocytes and immature dendritic cells, in host responses to bacterial infection. CCL20 production was induced in subcutaneous tissue in the BALB/c mouse in response to Salmonella enteritidis, Staphylococcus aureus and zymosan, with S. enteritidis being the most potent. S. enteritidis induced CCL20 production in the spleen following either oral administration or injection into the peritoneal cavity. In contrast, no increase was observed in the Peyer's patches. In this model, following intraperitoneal injection, dose-dependent colonization of the spleen and Peyer's patches by S. enteritidis, expression of IFNgamma and IL-4, and production of antibodies against the S. enteritidis surface antigen SefA were observed. Prior treatment with neutralizing antibodies against CCL20 enhanced bacterial dissemination to the spleen and Peyer's patches and strongly biased the IFNgamma/IL-4 ratio towards a type 2 profile in the spleen, while the humoral response was unaffected. In contrast, treatment with neutralizing anti-MIP-1alpha/CCL3 antibodies enhanced the bacterial burden in the Peyer's patches but not in the spleen, had no significant effect on the cytokine ratio, but significantly inhibited anti-SefA production. Together, these results demonstrate an important role for CCL20 in the control of bacterial infection and more specifically in the regulation of cell-mediated immunity against intracellular bacteria such as S. enteritidis.

Impact of Engagement of FcϵRI and CC Chemokine Receptor 1 on Mast Cell Activation and Motility

CC chemokines participate in the recruitment and activation of immune cells through CC chemokine receptors (CCRs). Here, we report that cross-talk between CCR1-mediated signaling pathway and FcepsilonRI-mediated signaling pathway affects degranulation positively but affects chemotaxis of mast cells adversely. Costimulation via FcepsilonRI engagement with IgE/antigen and CCR1 engagement with recombinant human CCL3 synergistically enhanced degranulation in rat basophilic leukemia-2H3 cells expressing human CCR1 (RBL-CCR1). Interestingly, FcepsilonRI engagement inhibited CCL3-mediated chemotaxis and membrane ruffling of RBL-CCR1 cells. Small GTP-binding proteins of the Rho family, Rac, Cdc42, and Rho control chemotaxis by mediating the reorganization of the actin cytoskeleton. Both a Rho inhibitor C3 exoenzyme and a Rho kinase (ROCK) inhibitor Y-27632 inhibited chemotaxis of RBL-CCR1 cells toward CCL3, indicating that activation of the Rho/ROCK signaling pathway is required for the CCL3-mediated chemotaxis of the cells. Costimulation with IgE/antigen and CCL3 enhanced Rac and Cdc42 activation but decreased ROCK activation in RBL-CCR1 cells compared with that in the cells stimulated with CCL3 alone. These results suggest that costimulation via FcepsilonRI and CCR1 engagements induced 1) inhibition of membrane ruffling, 2) decreased ROCK activation, and 3) reciprocal imbalance between Small GTP-binding proteins of the Rho family, which result in the inhibition of chemotaxis of RBL-CCR1 cells. The cross-talk between FcepsilonRI-mediated signaling pathway and CCR-mediated signaling pathway would induce optimal activation and arrested chemotaxis of mast cells, thus contributing to allergic inflammation.

CC chemokine ligands 25 and 28 play essential roles in intestinal extravasation of IgA antibody-secreting cells

CCL25 (also known as thymus-expressed chemokine) and CCL28 (also known as mucosae-associated epithelial chemokine) play important roles in mucosal immunity by recruiting IgA Ab-secreting cells (ASCs) into mucosal lamina propria. However, their exact roles in vivo still remain to be defined. In this study, we first demonstrated in mice that IgA ASCs in small intestine expressed CCR9, CCR10, and CXCR4 on the cell surface and migrated to their respective ligands CCL25, CCL28, and CXCL12 (also known as stromal cell-derived factor 1), whereas IgA ASCs in colon mainly expressed CCR10 and CXCR4 and migrated to CCL28 and CXCL12. Reciprocally, the epithelial cells of small intestine were immunologically positive for CCL25 and CCL28, whereas those of colon were positive for CCL28 and CXCL12. Furthermore, the venular endothelial cells in small intestine were positive for CCL25 and CCL28, whereas those in colon were positive for CCL28, suggesting their direct roles in extravasation of IgA ASCs. Consistently, in mice orally immunized with cholera toxin (CT), anti-CCL25 suppressed homing of CT-specific IgA ASCs into small intestine, whereas anti-CCL28 suppressed homing of CT-specific IgA ASCs into both small intestine and colon. Reciprocally, CT-specific ASCs and IgA titers in the blood were increased in mice treated with anti-CCL25 or anti-CCL28. Anti-CXCL12 had no such effects. Finally, both CCL25 and CCL28 were capable of enhancing alpha4 integrin-dependent adhesion of IgA ASCs to mucosal addressin cell adhesion molecule-1 and VCAM-1. Collectively, CCL25 and CCL28 play essential roles in intestinal homing of IgA ASCs primarily by mediating their extravasation into intestinal lamina propria.

CC Chemokine Ligand 25 Enhances Resistance to Apoptosis in CD4+ T Cells from Patients with T-Cell Lineage Acute and Chronic Lymphocytic Leukemia by Means of Livin Activation

We investigated CD4 and CD8 double-positive thymocytes, CD4(+) T cells from typical patients with T-cell lineage acute lymphocytic leukemia (T-ALL) and T cell lineage chronic lymphocytic leukemia (T-CLL), and MOLT4 T cells in terms of CC chemokine ligand 25 (CCL25) functions of induction of resistance to tumor necrosis factor alpha (TNF-alpha)-mediated apoptosis. We found that CCL25 selectively enhanced resistance to TNF-alpha-mediated apoptosis in T-ALL and T-CLL CD4(+) T cells as well as in MOLT4 T cells, but CD4 and CD8 double-positive thymocytes did not. One member protein of the inhibitor of apoptosis protein (IAP) family, Livin, was selectively expressed in the malignant cells at higher levels, particularly in T-ALL CD4(+) T cells, in comparison with the expression in CD4 and CD8 double-positive thymocytes. After stimulation with CCL25 and apoptotic induction with TNF-alpha, the expression levels of Livin in these malignant cells were significantly increased. CCL25/thymus-expressed chemokine (TECK), by means of CC chemokine receptor 9 (CCR9) ligation, selectively activated Livin to enhance resistance to TNF-alpha-mediated apoptosis in c-jun-NH(2)-kinase 1 (JNK1) kinase-dependent manner. These findings suggested differential functions of CCR9/CCL25 in distinct types of cells. CD4 and CD8 double-positive thymocytes used CCR9/CCL25 for migration, homing, development, maturation, selection, cell homeostasis, whereas malignant cells, particularly T-ALL CD4(+) T cells, used CCR9/CCL25 for infiltration, resistance to apoptosis, and inappropriate proliferation.

IL-9-mediated induction of eotaxin1/CCL11 in human airway smooth muscle cells

Recent work has shown the potential importance of IL-9 in allergic diseases. The development of transgenic mice overexpressing IL-9 has suggested a key role for this cytokine in the development of the asthmatic phenotype including airway eosinophilia. In this study, we evaluated the expression of the IL-9R and the effects of IL-9 on human ASM cells by examining the release of Th2-associated chemokines (eotaxin1/CCL11 and thymus- and activation-regulated chemokine (TARC)/CCL17). IL-9R alpha-chain mRNA and surface expression were detected in cultured human airway smooth muscle (ASM) cells. In addition, primary cultured ASM cells, as well as bronchial smooth muscle cells within biopsies of asthmatics and not control subjects, revealed IL-9R protein expression. IL-9 stimulation of human ASM cells resulted in release of eotaxin1/CCL11, but had no effect on the release of TARC/CCL17, in time- and dose-dependent manner. Moreover, in vitro chemotaxis assay demonstrated that conditioned medium from IL-9-stimulated ASM cells attracted human eosinophils. Neutralizing Abs to IL-9, but not to IL-4 or IL-13, reduced significantly IL-9-induced production of eotaxin1/CCL11 from ASM cells. Interestingly, real-time RT-PCR showed that IL-9 up-regulated eotaxin1/CCL11 mRNA expression, but had no effect on TARC/CCL17. Treatment with Act D abrogates IL-9-induced eotaxin1/CCL11 mRNA and protein release by ASM cells. Finally, transfection study using eotaxin1/CCL11 promoter luciferase construct confirmed that IL-9 induced eotaxin1/CCL11 at the transcriptional level. Taken together, these data provide new evidence demonstrating that IL-9-dependent activation of ASM cells contributes to eosinophilic inflammation observed in asthma.

Immunosuppression, eotaxin and the diagnostic changes in eosinophils that precede early acute heart allograft rejection

Peripheral blood eosinophil counts (EOS) are undetectable in 40% blood samples sent for routine haematology at Papworth Hospital during the first 3 months after heart transplantation (HTx). Increases in EOS usually precede the development of allograft rejection by a median of 4 days. We compared the effects of cyclosporin (dose and total blood concentration), prednisolone (dose and both total and unbound plasma concentrations) and azathioprine, as well as plasma concentrations of the CCR-3 chemokines, eotaxin and RANTES, on changes in EOS in 47 consecutive HTx recipients, with a median follow-up of 90 (IQR 85-95) days. Multivariate analysis confirmed the independent association between both prednisolone dose (P<0.0001) and eotaxin (P<0.0001) and changes in EOS. The plasma eotaxin concentration was, in turn, most closely associated with the cyclosporin dose (P<0.001) and plasma prednisolone concentration (P=0.022). The blood cyclosporin concentration (P=0.028), EOS (P=0.012) and prednisolone dose (P=0.015) were all independently associated with the risk of treated acute rejection. When prednisolone pharmacokinetic parameters were substituted for the prednisolone dose in this multivariate model, only the pharmacokinetic parameter retained a significant association with the risk of rejection. Changes in EOS preceding cardiac allograft rejection are directly associated with plasma eotaxin concentrations and indirectly with prednisolone dosage. Cyclosporin may also indirectly influence these changes by inhibiting eotaxin production. EOS, prednisolone dose and blood cyclosporin concentrations were independently associated with the risk of acute rejection. The total and unbound fractions of prednisolone in plasma appear to be even more closely related to rejection but are difficult to measure. Monitoring EOS, as a surrogate measure of prednisolone immunosuppression, may be more cost-effective for controlling rejection than conventional cyclosporin monitoring in the first 6 weeks after HTx.

The role of CCL21 in recruitment of T-precursor cells to fetal thymi

During embryonic development, T-lymphoid precursor cells colonize the thymus. Chemoattraction by the fetal thymus is thought to mediate T-precursor cell colonization. However, the molecules that attract T-precursor cells to the thymus remain unclear. By devising time-lapse visualization in culture, the present results show that alymphoid fetal thymus lobes attract T-precursor cells from fetal liver or fetal blood. CD4(-)CD8(-)CD25(-)CD44+ fetal thymocytes retained the activity to specifically re-enter the thymus. The attraction was predominantly due to I-A-expressing thymic epithelial cells and was mediated by pertussis toxin-sensitive G-protein signals. Among the chemokines produced by the fetal thymus, CCL21, CCL25, and CXCL12 could attract CD4(-)CD8(-)CD25(-)CD44+ fetal thymocytes. However, fetal thymus colonization was markedly diminished by neutralizing antibodies specific for CCL21 and CCL25, but not affected by anti-CXCL12 antibody. Fetal thymus colonization was partially defective in CCL21-deficient plt/plt mice and was further diminished by anti-CCL25 antibody. These results indicate that CCL21 is involved in the recruitment of T-cell precursors to the fetal thymus and suggest that the combination of CCL21 and CCL25 plays a major role in fetal thymus colonization.

STAT6-mediated signaling in Th2-dependent allergic asthma: critical role for the development of eosinophilia, airway hyper-responsiveness and mucus hypersecretion, distinct from its role in Th2 differentiation

When wild-type BALB/c mice were transferred with OVA-specific Th2 cells followed by OVA inhalation, a severe eosinophilia, mucus hypersecretion and airway hyper-responsiveness (AHR) was induced in parallel with a marked elevation of IL-4, IL-5 and IL-13 levels in bronchoalveolar lavage fluid (BALF). However, neither eosinophilia, AHR nor mucus hypersecretion was induced in Th2 cell-transferred STAT6-/- mice. The failure of eosinophilia was not due to the defect of Th2 cytokine production in BALF of STAT6-/- mice transferred with Th2 cells, but because of the defect of STAT6-dependent eotaxin production. Indeed, intranasal administration of eotaxin reconstituted pulmonary eosinophilia but not AHR and mucus hypersecretion in OVA-inhalated STAT6-/- mice. These results initially provided direct evidence that STAT6-dependent eotaxin production is essential for pulmonary eosinophilia. We also dissociated the role of STAT6 for eosinophilia from that for AHR and mucus hypersecretion. Thus, STAT6 also plays a critical role at late phase of Th2-dependent allergy induction.

Increase of CC chemokine receptor 4-positive cells in the peripheral CD4+ cells in dogs with atopic dermatitis or experimentally sensitized to Japanese cedar pollen

BACKGROUND

Since dogs frequently develop allergic diseases, similar to those in humans, dogs represent a possible animal model for allergy in humans. In human atopic dermatitis (AD), CC chemokine receptor 4 (CCR4) has been shown to play an important role in the development of allergic inflammation of AD; however, the association between allergic reaction and CCR4 is not well understood in dogs.

OBJECTIVE

To examine CCR4 expression in peripheral blood CD4+ cells in dogs that had AD and were experimentally sensitized with Japanese cedar pollen.

MATERIALS AND METHODS

Peripheral blood mononuclear cells (PBMCs) were isolated from 17 dogs with AD. The proportion of CCR4+ cells in peripheral blood CD4+ cells (CCR4/CD4) was evaluated by flow cytometry and compared with that in 10 healthy dogs. Similarly, in dogs that were experimentally sensitized to Japanese cedar pollen antigen, the proportion of CCR4/CD4 was examined pre- and post-sensitization.

RESULTS

The proportion of CCR4/CD4 in dogs with AD was 40.3+/-3.3%, which was significantly higher than that in normal dogs (23.6+/-4.3%) (P<0.01). In the experimentally sensitized dogs, the proportion of CCR4/CD4 was 25.4+/-2.6% at pre-sensitization and it was significantly increased (29.8+/-2.9%) at post-sensitization (P<0.01).

CONCLUSION

The proportion of CCR4+ cells in peripheral blood CD4+ cells was measured in dogs with allergic conditions. The present findings indicate that CCR4+ cells may be involved in the pathogenesis of allergy in dogs as in humans.

Specific recruitment of regulatory T cells in ovarian carcinoma fosters immune privilege and predicts reduced survival

Regulatory T (T(reg)) cells mediate homeostatic peripheral tolerance by suppressing autoreactive T cells. Failure of host antitumor immunity may be caused by exaggerated suppression of tumor-associated antigen-reactive lymphocytes mediated by T(reg) cells; however, definitive evidence that T(reg) cells have an immunopathological role in human cancer is lacking. Here we show, in detailed studies of CD4(+)CD25(+)FOXP3(+) T(reg) cells in 104 individuals affected with ovarian carcinoma, that human tumor T(reg) cells suppress tumor-specific T cell immunity and contribute to growth of human tumors in vivo. We also show that tumor T(reg) cells are associated with a high death hazard and reduced survival. Human T(reg) cells preferentially move to and accumulate in tumors and ascites, but rarely enter draining lymph nodes in later cancer stages. Tumor cells and microenvironmental macrophages produce the chemokine CCL22, which mediates trafficking of T(reg) cells to the tumor. This specific recruitment of T(reg) cells represents a mechanism by which tumors may foster immune privilege. Thus, blocking T(reg) cell migration or function may help to defeat human cancer.

A stroma-derived defect in NF-kappaB2-/- mice causes impaired lymph node development and lymphocyte recruitment

The NF-kappaB family of transcription factors is vital to all aspects of immune function and regulation in both the hemopoietic and stromal compartments of immune environments. Recent studies of mouse models deficient for specific members of the NF-kappaB family have revealed critical roles for these proteins in the process of secondary lymphoid tissue organogenesis. In this study, we investigate the role of NF-kappaB family member NF-kappaB2 in lymph node development and lymphocyte recruitment. Inguinal lymph nodes in nfkappab2(-/-) mice are reduced in size and cellularity, most notably in the B cell compartment. Using in vitro and in vivo lymph node grafting assays, we show that the defect resides in the stromal compartment. Further examination of the nfkappab2(-/-) inguinal lymph nodes revealed that expression of peripheral node addressin components CD34 and glycosylation-dependent cell adhesion molecule-1 along with the high endothelial venule-restricted sulfotransferase HEC-GlcNAc6ST was markedly reduced. Furthermore, expression of the lymphocyte homing chemokines CCL19, CCL21, and CXCL13 was down-regulated. These data highlight the role of NF-kappaB2 in inguinal lymph node organogenesis and recruitment of lymphocytes to these organs due to its role in up-regulation of essential cell adhesion molecules and chemokines, while suggesting a potential role for NF-kappaB2 in organization of lymph node endothelium.

Expression profiling identifies chemokine (C-C motif) ligand 18 as an independent prognostic indicator in gastric cancer

BACKGROUND & AIMS

Gastric cancer is one of the major cancers worldwide. Expression profiling has proven useful in delineating novel prognostic markers in various cancer types. We previously analyzed gene-expression patterns in 90 gastric adenocarcinomas by using complementary DNA microarrays and prioritized a list of genes whose expression levels predict patient outcome.

METHODS

We identified a specific gene of interest, chemokine (C-C motif) ligand 18 (CCL18), on the basis of a high absolute standardized log Cox hazard ratio, a high variance in expression among all tumor samples, and putative biologic function. Detailed analysis of CCL18 expression with clinicopathologic and survival data was performed (n = 89). Quantitative reverse-transcription polymerase chain reaction was used to verify the microarray expression data and was further applied to analyze an independent cohort of tumor samples (n = 59). The cellular source of CCL18 was determined with immunohistochemistry and in situ hybridization.

RESULTS

High CCL18 expression levels were associated with prolonged overall (P = 0.001; hazard ratio, 0.586) and disease-free (P = 0.002; hazard ratio, 0.416) patient survival in the array-based data set by univariate analysis. The observations were confirmed in an independent set of 59 patients by using quantitative reverse-transcription polymerase chain reaction. In multivariate analysis, tumor stage and CCL18 levels were independent prognostic factors for predicting both overall and disease-free survival. We found that CCL18 was expressed by a subpopulation of tumor-associated macrophages that were preferentially located at the tumor invasion front.

CONCLUSIONS

Macrophage-derived CCL18 may function as a local antitumor immunomodulator that affects patient outcome. Our study suggests CCL18 as a novel candidate for antitumor therapeutics and risk stratification in gastric cancer patients.

Production of granulomatous inflammation in lungs of rat pups and adults by Sephadex beads

Granulomatous inflammation is a process that involves mononuclear leukocytes as well as other inflammatory cells. The heterogeneity of its appearance may be due to the variety of cytokines and chemokines that are involved. In this study, we compared granuloma formation and bronchoalveolar leukocyte differential in the lungs of rats (2- and 8-wk-old) that were treated intravenously with Sephadex beads. In addition, the kinetics of cytokine and chemokine production was determined in these groups. In adults, the beads caused lung granulomas associated with infiltration of eosinophils and neutrophils and increased eosinophil and neutrophil counts in the bronchoalveolar lavage fluid within 16 h. In pups, the granulomas were formed slowly and did not reach the size achieved in adults. Eosinophils and neutrophils were sparsely found in the periphery of the granulomas, even at 32 h. Pups were also unable to respond rapidly to Sephadex bead treatment with eosinophil and neutrophil infiltration in the bronchoalveolar lavage fluid. Tumor necrosis factor-alpha was significantly increased in both groups, but the cytokine was lower in pups than in adults. Interferon-gamma and eotaxin were increased only in adults, and IL-4 and regulated on activation, normal T cell expressed, and secreted was increased only in pups. In conclusion, the i.v. administration of Sephadex beads produced granulomatous inflammation in the lungs of adult rats, but pups were unable to respond as rapidly to the treatment. In addition, the difference in response between the two age groups was associated with the kinetics of cytokine and chemokine production.