Macrophage phenotype as a determinant of biologic scaffold remodeling

Macrophage phenotype can be characterized as proinflammatory (M1) or immunomodulatory and tissue remodeling (M2). The present study used a rat model to determine the macrophage phenotype at the site of implantation of two biologic scaffolds that were derived from porcine small intestinal submucosa (SIS) and that differed mainly according to their method of processing: the Restore device (SIS) and the CuffPatch device (carbodiimide crosslinked form of porcine-derived SIS (CDI-SIS)). An autologous tissue graft was used as a control implant. Immunohistologic methods were used to identify macrophage surface markers CD68 (pan macrophages), CD80 and CCR7 (M1 profile), and CD163 (M2 profile) during the remodeling process. All graft sites were characterized by the dense population of CD68+ mononuclear cells present during the first 4 weeks. The SIS device elicited a predominantly CD163+ response (M2 profile, p < 0.001) and showed constructive remodeling at 16 weeks. The CDI-SIS device showed a predominately CD80+ and CCR7+ response (M1 profile, p < 0.03), and at 16 weeks was characterized by chronic inflammation. The autologous tissue graft showed a predominately CD163+ response (M2) at 1 week, with a dual M1/M2 population (CD80+, CCR7+, and CD163+) by 2 and 4 weeks and moderately well organized connective tissue by 16 weeks. The processing methods used during the manufacturing of a biologic scaffold can have a profound influence upon the macrophage phenotype profile and downstream remodeling events. Routine histologic examination alone is inadequate to determine the phenotype of mononuclear cells that participate in the host response to the scaffold.     

Chemokine receptor expression and modulation by Mycobacterium tuberculosis antigens on mononuclear cells from human lymphoid tissues

Chemokine receptor switching on lymphoid cells is an important factor regulating migration and homing, but little is known about the expression of such molecules during Mycobacterium tuberculosis infection in humans. We describe CCR2, CCR5 and CCR7 expression on human cells from blood, spleen and pulmonary hilar lymph nodes (PHLN) stimulated by M. tuberculosis antigens. CCR2 was not expressed by CD3+ cells regardless of the presence of antigen, but was highly expressed on CD14+ CD63+ monocytes/macrophages. CCR2 decreased on splenic monocytes/macrophages by nearly 50% in culture, independent of antigen, but remained high in blood and PHLN. CCR5 was low in CD3+ cells and was down-regulated by M. tuberculosis antigens on blood and splenic cells but not in PHLN. CCR5 was highly expressed on monocytes/macrophages and was down-regulated by M. tuberculosis antigens at 48 hr only in blood. Less than 15% of CD3+ cells from spleen and PHLN were CCR7+, whereas nearly 40% from blood expressed this receptor on primary isolation. However, CCR7 in PHLN increased in culture, independent of antigen. Monocytes/macrophages did not express CCR7. Thus, we characterize, for the first time, chemokine receptor expression and differential modulation by M. tuberculosis antigens on human mononuclear cells from spleen, blood and PHLN. Knowledge of chemokine receptor switching in human lymphoid tissue provides novel insight into mechanisms of the immune response to M. tuberculosis with potential effects on directing cell trafficking.     

CC chemokine receptor 4 ligand production by bronchoalveolar lavage fluid cells in cigarette-smoke-associated acute eosinophilic pneumonia

We examined the production of macrophage-derived chemokine (MDC/CCL22) and thymus- and activation-regulated chemokine (TARC/CCL17) by bronchoalveolar lavage fluid (BALF) cells in cigarette-smoke-associated acute eosinophilic pneumonia (CS-AEP). The CC Chemokine Receptor 4 (CCR4) ligand levels in BALF from patients with CS-AEP were considerably higher than those in healthy volunteers and correlated well with Th2 cytokine levels. Interleukin-4 enhanced CCR4 ligand production. MDC expression was observed in CD68-positive cells from patients with CS-AEP and in healthy control smokers. In contrast, TARC expression in CD68- or CD1a-positive cells was detected only in CS-AEP. An in vivo cigarette smoke challenge test induced increases in CCR4 ligands in the BALF and in the cultured supernatant of BALF adherent cells. These results suggest that alveolar macrophages and dendritic cells contribute to the pathogenesis of CS-AEP by generating CCR4 ligands, probably in response to cigarette smoke.     

组织细胞坏死性淋巴结炎中CD123及MPO的表达及意义

目的探讨CD123和MPO在组织细胞坏死性淋巴结炎(histiocytic necrotizing lymphadenitis,HNL)中的表达及在诊断和鉴别诊断中的价值。方法对39例HNL进行常规形态学观察和免疫组化标记,12例淋巴组织反应性增生性病变和12例弥漫性大B细胞淋巴瘤作为对照。结果 CD123在HNL中的阳性率为89.7%,淋巴组织反应性增生性病变中的阳性率为33.3%(P<0.01),弥漫性大B细胞性淋巴瘤中的阳性率为16.7%(P<0.01),其CD123敏感性为90%,特异性为75%;MPO的敏感性为82%,特异性为88%,两者联合应用,其敏感性为79%,特异性为96%。结论 CD123和MPO在HNL中均具有较高的阳性率,其敏感性和特异性均较好,具有很好的诊断和鉴别诊断价值,是诊断HNL较为理想的免疫标记物。     

Chemokine responsiveness of CD4+ CD25+ regulatory and CD4+ CD25− T cells from atopic and nonatopic donors

Background:  Allergic inflammation is associated with Th2-type T cells, which can be suppressed by CD4+ CD25+ regulatory T cells (Tregs). Both express chemokine receptors (CCR) 4 and CCR8, but the dynamics of expression and effect of atopic status are unknown.
Objective:  To examine the expression of chemokine receptors by CD4+ CD25+ and CD4+ CD25− T cells from atopic and nonatopic donors, and document response to allergen stimulation in vitro .
Methods:  Chemokine receptor expression was examined by flow cytometry and quantitative PCR of CD4+ CD25hi and CD4+ CD25− T cells from atopics and nonatopics. Responsiveness to chemokines was by actin polymerization. Dynamics of chemokine receptor expression in 6-day allergen-stimulated cultures was analysed by carboxyfluoroscein succinimidyl ester labelling.
Results:  CD4+ CD25hi Tregs preferentially expressed CCR3, CCR4, CCR5, CCR6 and CCR8. CD4+ CD25hi Tregs responded to the chemokine ligands for CCR4, CCR6 and CCR8 (CCL17, 22, 20 and 1 respectively), with no differences between atopic and nonatopic donors. Over 6-day allergen stimulation, CD4+ CD25+ T-cells downregulated CCR4 and upregulated CCR7, in contrast to CD4+ CD25− effector cells, which downregulated CCR7 and upregulated CCR4.
Conclusions:  CCR4, CCR6 and CCR8 have potential roles in localization of both CD4+ CD25+ regulatory and CD4+ CD25− effector T cells to sites of allergic inflammation. Upregulation of CCR7 and downregulation of CCR4 upon allergen stimulation of Tregs may allow their recirculation from sites of inflammation, in contrast to retention of effector T cells.     

Plasma cell-like morphology of Th1-cytokine-producing cells associated with the loss of CD3 expression

Here we clarified the morphology and phenotype of interleukin (IL)-17- and interferon (IFN)-gamma-producing cells in both in vitro and in vivo situations. Oligoclonal activation of normal peripheral blood mononuclear cells with the superantigen Staphylococcus aureus enterotoxin B and polyclonal activation with phorbol myristate acetate/phytohemagglutinin were used as in vitro models. This study was extended to various in vivo situations such as rheumatoid arthritis, dermatomyositis, and normal activated lymph nodes. The phenotype of IL-17- and IFN-gamma-producing cells was evaluated by immunohistochemistry using the CD3 and CD4 T-cell markers, the CD20, CD38, kappa and lambda light chain B-cell lineage markers. The expression of two chemokine receptors, CCR6 and CCR7, involved with their associated ligands CCL20 and CCL19/CCL21 in the migration of T lymphocytes, was evaluated in tissue sections. After both polyclonal and oligoclonal activation, IL-17+ and IFN-gamma+ cells acquired a plasma cell-like morphology associated with a high secretory activity, the reduced expression of CD3, and no change of CD4 expression. In rheumatoid arthritis, dermatomyositis, and activated lymph nodes, both IL-17- and IFN-gamma-producing cells had the same morphology. These Th1 cytokine-producing cells were CD4(+)-, CD3-, and B-cell lineage marker-negative. In both in vitro and in vivo situations, expression of CCR6 or CCR7 was not associated with a particular subset. In conclusion, activated T-helper CD4(+) T cells, by their release of cytokines, seem to have functional similarities with plasma cells secreting immunoglobulins.     

Peripheral Monocyte Expression of the Chemokine Receptors CCR2, CCR5 and CXCR3 is Altered at Parturition in Healthy Women and in Women with Systemic Lupus Erythematosus

Monocytes are precursors of macrophages and recruited to the uterus throughout pregnancy to perform important immunological functions. In this study, we hypothesized that pregnant women have reduced peripheral monocyte expression of chemokine receptors and alterations in PBMC responses to microbial stimuli as an adaption to pregnancy and that these changes are less pronounced in women with autoimmunity. We therefore investigated the chemokine receptor expression, migratory behaviour and responses to microbial stimulation of peripheral monocytes from pregnant women at parturition (n = 13) and from non‐pregnant women (n = 9). In addition, we compared healthy pregnant women with women suffering from SLE (n = 5), a condition with pronounced systemic inflammation increasing the risk for pregnancy complications. We demonstrate that peripheral monocytes are affected by pregnancy with reduced percentages of CCR2+, CCR5+ and CXCR3+ monocytes of both classical (CD16?) and inflammatory (CD16+) subsets and that the trophoblast‐secreted chemokine CCL2/MCP‐1 recruited monocytes of both subsets in vitro. Further, PBMCs from pregnant women had a divergent response to microbial stimulation with lower CCL5/RANTES and higher CCL2/MCP‐1 secretion compared with non‐pregnant women. In addition, pregnant women had lower basal PBMC‐secretion of CCL5/RANTES and higher basal secretion of IL‐10 and CCL2/MCP‐1. Interestingly, the women with SLE responded similar to pregnancy as did healthy women with lower percentages of CCR2+, CCR5+ and CXCR3+ monocytes. However, they had increased expression of CCR5 on CD16+ monocytes and heightened PBMC‐secretion of CCL5/RANTES. In conclusion, our data indicate that monocyte chemokine receptor expression and the chemokine milieu during pregnancy are tightly regulated to support pregnancy.     

The Lymphoid Chemokine CCL21 Enhances the Cytotoxic T Lymphocyte‐Inducing Functions of Dendritic Cells

The potential use of lymphoid chemokines to generate a dendritic cell (DC) cancer vaccine is not yet clear. We investigated the effect of lymphoid chemokines on DC function and on the production of effective cytotoxic T lymphocytes (CTLs) for application of cancer vaccine using monocyte‐derived mature DCs (mDCs) prestimulated with lymphoid chemokines. mDCs exposed to a secondary lymphoid organ chemokine (SLC/CCL21) dramatically induced CTL response by increasing cytolytic activity without any significant alterations on expression of cell surface markers (e.g. CD80, CD83, CD86 and CCR7) or on the production of cytokines (e.g. IL‐12p70, IL‐10 and IL‐23). Interestingly, mDCs prestimulated with CCL21 showed higher levels of CXCL10 (IP‐10) production, but not the production of CCL22, compared with untreated mDCs. IP‐10 treatment during CTL generation with DCs dramatically enhanced tumour‐specific CTL response compared with untreated CTLs, and these enhanced CTL‐inducing functions of CCL21‐treated DCs were inhibited by anti‐IP‐10 treatment. Taken together, our data suggested an important role of the lymphoid‐endothelium‐associated chemokine, CCL21, on DCs in the induction of CTL responses.     

Trafficking pathways and characterization of CD4 and CD8 cells recruited to the skin of humans experimentally infected with Haemophilus ducreyi

T-cell homing to infected skin is not well studied in humans. We examined sites experimentally infected with Haemophilus ducreyi by immunohistochemistry and flow cytometry for expression of receptors and ligands involved in cutaneous T-cell homing and determined the phenotypes of the T cells that trafficked to skin. Endothelial cells expressed E-selectin in infected but not uninfected skin, while peripheral node addressin (PNAd) was minimally expressed in all samples. CC chemokine ligand 27 (CCL27) was expressed in the epidermis and endothelium of both infected and uninfected skin. Interestingly, CCL21, a chemokine thought to be associated principally with T-cell trafficking in the lymphatic compartment, was highly expressed on the endothelium of infected skin. Few naive cells were present in experimental lesions, emphasizing the combined role of PNAd and CCL21 in trafficking of this subset. Memory cells (CD45RA-) dominated both CD4 and CD8 T-cell populations at the site of infection. Effector memory (CD45RA- CD27-) CD4+ and CD8+ T cells were enriched in lesions. Although the CC chemokine receptor 7-positive (CCR7+) population of both central memory (CD45RA- CD27+) and effector memory cells was not enriched in the skin compared to peripheral blood, CCR7+ cells were not precluded from entering infected skin. Taken together with our previous work (D. Soler, T. L. Humphreys, S. M. Spinola, and J. J. Campbell, Blood 101:1677-1683, 2003), these studies led us to propose a model of memory T-cell trafficking to skin in response to experimental H. ducreyi infection.     

Dominance of CCL22 over CCL17 in induction of chemokine receptor CCR4 desensitization and internalization on human Th2 cells

Chemokines and their receptors play a pivotal role in controlling T cell trafficking in immunity and inflammation. Two chemokines, CCL17 and CCL22, activate the chemokine receptor CCR4, expressed on functionally distinct subsets of T cells: cutaneous leukocyte-associated antigen (CLA)+ skin-homing, T helper (Th) 2, and CD25+ T suppressor cells. Here, we compared the ability of CCL17 and CCL22 to promote CCR4 internalization as a mechanism of regulation of receptor function on human Th2 cells. We report that CCL22 is a potent and rapid inducer of CCR4 internalization, while CCL17 is not. CCR4 internalization does not require G protein coupling, while being dependent on lipid rafts integrity and clathrin-coated pits functionality. Cell surface disappearance of CCR4 is rapidly reversed upon removal of exogenous ligand by virtue of receptor recycling. CCR4 internalization leads to a loss of functional responsiveness, while recovery of surface expression leads to re-acquisition of chemotactic sensitivity of Th2 cells. The differential CCR4 desensitization and internalization reported here and the distinct expression patterns of CCL17 and CCL22 observed in vivo suggest that while CCL17 may act first on CCR4 at the endothelial surface to promote vascular recognition, CCL22 could subsequently engage the receptor within the tissue microenvironment to guide cellular localization.     

CD8 chemokine receptors in chronic obstructive pulmonary disease

Increased lung CD8 cells and their expression of chemokine receptors CXCR3 and CCR5 have been previously reported in chronic obstructive pulmonary disease (COPD). Alterations of CD8-CCR3 and -CCR4 expression and their ligands in COPD patients have not been fully investigated. The objective of this study was to assess in COPD patients: (i) broncho-alveolar lavage (BAL) CD8 CCR3 and CCR4 expression in COPD patients; and (ii) airway levels of the CCR3 ligands, CCL11 and CCL5. Multi-parameter flow cytometric analysis was used to assess BAL CD3 and CD8-chemokine receptor expression in COPD patients, smokers and healthy non-smokers (HNS). CCL5 and CCL11 levels were measured in BAL, and from the supernatants of lung resection explant cultures. CD8-CCR3 and -CCR5 expression (means) were increased in COPD patients (22% and 46% respectively) and smokers (20% and 45%) compared with HNS (3% and 22%); P < 0.05 for all comparisons. CD3CXCR3 expression was raised in smokers and COPD while CD8CXCR3 and CD3 and CD8 CCR4 expression was similar between groups. CD8CCR5 expression correlated to smoking pack years (r = 0.42, P = 0.01). COPD explants released more CCL5 compared with smokers (P = 0.02), while there was low level CCL11 production. CD8CCR3 and CCR5 expression appear to be regulated by cigarette smoke exposure. We show that COPD lung tissue released more CCL5, suggesting a role for CCL5-CCR3 signalling in pulmonary CD8 recruitment in COPD.     

Skin reactivity and local cell recruitment in human atopic and nonatopic subjects by CCL2/MCP-1 and CCL3/MIP-1alpha

Background:  Monocyte chemotactic protein (MCP-1/CCL2), the ligand for CCR2 and CCR5, and macrophage inflammatory protein-1α (MIP-1α/CCL3), the ligand for CCR1 and CCR5, are potent chemo-attractants in vitro and produce lesions in experimental animals, which resemble immediate and delayed-type hypersensitivity (DTH) reactions. CCL3 induces mononuclear cell and granulocyte infiltration in human atopic and nonatopic skin. Whether CCL2 (MCP-1) has comparable activity in man is uncertain as is the capacity of both the chemokines to elicit immediate- and DTH-like reactions in humans.
Methods:  Inflammatory cells were counted by immunohistochemistry in 24 and 48-h skin biopsies from atopics and nonatopics after intradermal injection of CCL2 and CCL3. Immediate (15 min) wheals-and-flares and delayed (24 and 48 h) indurations were also recorded.
Results:  Both chemokines induced immediate- (15 min) and delayed (24 and 48 h) reactions, which were associated with significant infiltrations of CD68+ macrophages, CD3+, CD4+ (but not CD8+) T cells, neutrophils, and eosinophils in biopsies from injection sites. CCL2, but not CCL3, also induced infiltration of basophils. Neither chemokine produced significant changes in the numbers of tryptase+ cutaneous mast cells. There were no differences in the pattern of skin reactivity or the numbers of infiltrating leukocytes in response to CCL2 and CCL3 between atopic and nonatopic subjects. In general, maximal infiltration of inflammatory cells was observed at the 24-h, rather than the 48-h, time point.
Conclusions:  CCL2 and CCL3 induce both immediate and delayed skin reactions in atopics and nonatopics, and evoke a similar profile of local T cell/macrophage and granulocyte recruitment which, in general, confirm previous in vitro findings and in vivo experimental animal data.     

Skin-homing CLA+ T cells and regulatory CD25+ T cells represent major subsets of human peripheral blood memory T cells migrating in response to CCL1/I-309

Functionally distinct T cell subsets exhibit specific chemokine receptor profiles that regulate their tissue localization. Here, we show that human peripheral blood CD4(+) and CD8(+) cutaneous (CLA(+)), but not intestinal memory (integrin beta(7) (+)) nor IL-4-producing T cells, represent major subpopulations of circulating T cells that specifically migrate in response to the chemokine I-309/CCL1 by virtue of CCR8 expression. Expression of CCR8 is markedly up-regulated upon activation and in vitro culture of human CLA(+) T cells, suggesting the involvement of CCR8 in localization of cutaneous memory T cells to the skin. Interestingly, amongst circulating memory CD4(+)CD45RO(+) T cells, chemotactic responsiveness to CCL1 is restricted to cells expressing CD25 and/or CLA surface markers for regulatory T cells (Treg) and skin-homing T cells and maximal responsiveness is observed on CLA(+)CD25(+)T cells. Such pattern of CCL1 responsiveness suggests that the CCR8/CCL1 axis may regulate trafficking of cutaneous Treg and memory T cells into the skin.     

趋化性细胞因子CCL28的功能与表达

CCL28是新近发现的趋化性细胞因子家族CC类中的成员。多种粘膜组织的上皮细胞可以产生CCL28,其受体为CCR10和CCR3。通过与相应受体结合,CCL28可介导血循环中的CD4^＋T细胞、CD8^＋T细胞、IgA抗体分泌细胞（ASC）等免疫活性细胞归巢迁徙至相关组织;另外,CCL28还具有明显的广谱抗微生物活性。因而,在粘膜免疫及某些肿瘤的免疫中,CCL28发挥着重要作用。CCL28的表达受到多种内外因素的影响。对其表达调节机制的阐明,必将为相关疾病的防治研究提供新的思路。     

Chemokines and other GPCR ligands synergize in receptor-mediated migration of monocyte-derived immature and mature dendritic cells

Dendritic cells (DCs) are potent antigen presenting cells, described as the initiators of adaptive immune responses. Immature monocyte-derived DCs (MDDC) showed decreased CD14 expression, increased cell surface markers DC-SIGN and CD1a and enhanced levels of receptors for the chemokines CCL3 (CCR1/CCR5) and CXCL8 (CXCR1/CXCR2) compared with human CD14⁺ monocytes. After further MDDC maturation by LPS, the markers CD80 and CD83 and the chemokine receptors CXCR4 and CCR7 were upregulated, whereas CCR1, CCR2 and CCR5 expression was reduced. CCL3 dose-dependently synergized with CXCL8 or CXCL12 in chemotaxis of immature MDDC. CXCL12 augmented the CCL3-induced ERK1/2 and Akt phosphorylation in immature MDDC, although the synergy between CCL3 and CXCL12 in chemotaxis of immature MDDC was dependent on the Akt signaling pathway but not on ERK1/2 phosphorylation. CCL2 also synergized with CXCL12 in immature MDDC migration. Moreover, two CXC chemokines not sharing receptors (CXCL12 and CXCL8) cooperated in immature MDDC chemotaxis, whereas two CC chemokines (CCL3 and CCL7) sharing CCR1 did not. Further, the non-chemokine G protein-coupled receptor ligands chemerin and fMLP synergized with respectively CCL7 and CCL3 in immature MDDC signaling and migration. Finally, CXCL12 and CCL3 did not cooperate, but CXCL12 synergized with CCL21 in mature MDDC chemotaxis. Thus, chemokine synergy in immature and mature MDDC migration is dose-dependently regulated by chemokines via alterations in their chemokine receptor expression pattern according to their role in immune responses.     

The chemokine CCL18 causes maturation of cultured monocytes to macrophages in the M2 spectrum

The observation that human monocytes cultured in the presence of the chemokine CCL18 showed increased survival, led us to profile cytokine expression in CCL18-stimulated versus control cultures. CCL18 caused significantly increased expression of chemokines (CXCL8, CCL2, CCL3 and CCL22), interleukin-10 (IL-10) and platelet-derived growth factor, but no up-regulation of M1 cytokines IL-1β or IL-12. CCL18-stimulated monocytes matured into cells with morphological resemblance to IL-4-stimulated macrophages, and expressed the monocyte marker CD14 as well the M2 macrophage markers CD206 and 15-lipoxygenase, but no mature dendritic cell markers (CD80, CD83 or CD86). Functionally, CCL18-stimulated macrophages showed a high capacity for unspecific phagocytosis and for pinocytosis, which was not associated with an oxidative burst. These findings suggest that CCL18-activated macrophages stand at the cross-roads between inflammation and its resolution. The chemokines that are produced in response to CCL18 are angiogenic and attract various leucocyte populations, which sustain inflammation. However, the capacity of these cells to remove cellular debris without causing oxidative damage and the production of the anti-inflammatory IL-10 will initiate termination of the inflammatory response. In summary, CCL18 induces an M2 spectrum macrophage phenotype in the absence of IL-4.     

Differential expression of chemokine receptors on human IgA+ and IgG+ B cells

Organ-specific lymphocyte homing is dependent on the expression of tissue-specific homing receptors and selected chemokine receptors. During the effector phase of an immune response, IgA and IgG antibody-secreting cells (ASC) are differently distributed in the body. Still, B cell expression of L-selectin and the mucosal homing receptor integrin alpha4beta7 is not related to the isotype produced, but only to the site of antigen encounter. In this study, we examined if differences in chemokine responsiveness between IgA+ and IgG+ B cells could explain their different tissue localization. Circulating CD19+ B cells were isolated and their expression of IgA, IgG, and selected chemokine receptors was determined by flow cytometry. Few Ig+ cells expressed CCR2, CCR3, or CCR9, and there was no difference in the expression of these receptors between IgA+ and IgG+ cells. In contrast, CCR4, CCR5, and CXCR3 was expressed on significantly more IgG+ than IgA+ cells. The function of chemokine receptors on memory B cells and ASC was then tested in the transwell system. IgG+ memory cells migrated to a higher extent than IgA+ cells towards the CXCR3 ligand CXCL11/I-TAC, while there was only a small migration towards the CCR4 ligand CCL17/TARC and the CCR9 ligand CCL25/TECK. ASC migrated poorly to all chemokines tested. In conclusion, this study shows that IgG+ and IgA+ memory B cells have a differential expression of the Th1 associated chemokine receptor CXCR3, as well as of CCR4 and CCR5. In contrast, none of the studied chemokine receptors was preferentially expressed by IgA+ cells.     

Enhanced allergen-induced airway inflammation in paucity of lymph node T cell (plt) mutant mice

BACKGROUND: Dendritic cells and lymphocytes play a central role in allergic asthma. Chemokines for these cells include the CCR7 agonists secondary lymphoid chemokine/CCL21 and EBV-induced lymphoid chemokine/CCL19, but their role in allergic asthma is poorly understood. OBJECTIVE: We sought to determine the effects of abrogation of lymphoid tissue expression of CCR7 agonists on allergic airway responses. METHODS: Paucity of lymphocyte T cell (plt) mutant mice, deficient in EBV-induced lymphoid chemokine/CCL19 and the lymphoid form of secondary lymphoid chemokine/CCL21, were evaluated in an established ovalbumin (OVA)-induced asthma model (plt-OVA group) and compared with similarly immunized +/+ BALB/c mice (+/+OVA group). RESULTS: APTI responses to methacholine increased similarly in OVA-challenged plt and +/+ mice. However, airway inflammation was strikingly enhanced in plt-OVA mutants over +/+OVA mice and included increased numbers of eosinophils, CD4 and B cells, neutrophils, and total leukocytes in bronchoalveolar lavage fluid and inflammatory cell cuffing around pulmonary arterioles. Enhanced airway inflammation was accompanied by an increase in lung T(H)2 activity, with increased levels of IL-4 and monocyte-derived chemoattractant/CCL22. CONCLUSIONS: Induction of allergic asthma in mutant mice with impaired CCR7 responses results in characteristics that resemble severe asthma in human subjects, including severe bronchial lymphocytosis, eosinophilia, and neutrophilia, but not in enhancement in airway hyperreactivity. CLINICAL IMPLICATIONS: Disruption of chemokines responsible for trafficking of antigen-processing cells and lymphocytes to the draining lymph nodes might lead to enhanced allergic airway responses.     

Differential expression of the chemokine receptors CX3CR1 and CCR1 by microglia and macrophages in myelin-oligodendrocyte-glycoprotein-induced experimental autoimmune encephalomyelitis

Chemokines are important for the recruitment of immune cells into sites of inflammation. To better understand their functional roles during inflammation we have here studied the in vivo expression of receptors for the chemokines CCL3/CCL5/CCL7 (MIP-1alpha/RANTES/MCP-3) and CX3CL1 (fractalkine), CCR1 and CX3CR1, respectively, in rat myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis. Combined in situ hybridization and immunohistochemistry demonstrated intensely upregulated CCR1 mRNA expression in early, actively demyelinating plaques, whereas CX3CR1 displayed a more generalized expression pattern. CX3CR1 mRNA expressing cells were identified as microglia on the basis of their cellular morphology and positive GSA/B4 lectin staining. In contrast, CCR1 mRNA was preferentially expressed by ED1+ GSA/B4+ macrophages. The notion of differential chemokine receptor expression in microglia and monocyte-derived macrophages was corroborated at the protein level by extraction and flow cytometric sorting of cells infiltrating the spinal cord using gating for the surface markers CD45, ED-2 and CD11b. These observations suggest a differential receptor expression between microglia and monocyte-derived macrophages and that mainly the latter cell type is responsible for active demyelination. This has great relevance for the possibility of therapeutic intervention in demyelinating diseases such as multiple sclerosis, for example by targeting signaling events leading to monocyte recruitment.     

Chemotaxis of human tonsil B lymphocytes to CC chemokine receptor (CCR) 1, CCR2 and CCR4 ligands is restricted to non-germinal center cells

We have investigated the effects of nine CC chemokines, i.e. macrophage inflammatory protein (MIP)-1alpha/CCL3, MIP-1beta/CCL4, MIP-3alpha/CCL20, MIP-5/CCL15, monocyte chemotactic protein (MCP)-1/CCL2, MCP-2/CCL8, MCP-3/CCL7, eotaxin/CCL11 and macrophage-derived chemokine (MDC)/CCL22 on the locomotion of human tonsil B lymphocytes and their subsets. Upon isolation, B cells were poorly responsive, but, following short-term culture, they displayed statistically significant chemotactic responses (P < 0.001) to MIP-1alpha, MIP-5, MCP-1, MCP-2, MCP-3 and MDC. CC chemokine receptor (CCR) 1 to CCR6 were up-regulated after culture. MIP-1beta, MIP-3alpha and eotaxin did not stimulate B cell migration. Scattered information is available on B cell subset responses to chemokines. Therefore, we investigated the effects of MIP-1alpha, MIP-5, MCP-1, MCP-2, MCP-3 and MDC on the in vitro locomotion of non-germinal center (GC) (CD38(-)) and GC (CD38(+)) B cells. All chemokines enhanced significantly (P < 0.001) the migration of the former, but not of the latter, cells. CCR1, CCR2 and CCR4 were detected by flow cytometry on non-GC (i.e. naive and memory) B cells, whereas they were absent (CCR1 and CCR2) or poorly expressed (CCR4) on GC B cells.