Thymus- and activation-regulated chemokine (TARC/CCL17) induces a Th2-dominated inflammatory reaction on intradermal injection in mice

TARC/CCL17 (thymus- and activation-regulated chemokine) is a CC chemokine, which binds to the CC chemokine receptor-4 (CCR4) known to be distinctively expressed on Th2 lymphocytes. In atopic dermatitis (AD), the skin is invaded by Th2 lymphocytes in the acute phase. TARC/CCL17 is produced by the keratinocytes in AD lesions, and CCR4 is overexpressed on CLA+ (cutaneous lymphocyte-associated antigen) lymphocytes in the skin and blood. We, therefore, hypothesized that TARC/CCL17 is pivotal in mediating a Th2-dominated inflammation in the skin. To examine this, we injected BALB/c mice with murine TARC/CCL17 in concentrations ranging from 0.1 microg/ml to 10 microg/ml and examined the skin after 48 h. This revealed that TARC/CCL17 induces lymphocytic infiltration of the skin by CD4+ lymphocytes in a dose-dependent manner with a maximum response at 1 microg/ml. Additionally, TARC/CCL17 induced interleukin-4 mRNA but not interferon-gamma mRNA expression in the skin, suggesting that the lymphocytes invading the skin are Th2 cells. Additionally, TARC/CCL17 induced its own production in the keratinocytes along with cutaneous T-cell-attracting chemokine (CTACK/CCL27) mRNA. We, therefore, conclude that TARC/CCL17 induces a Th2-dominated inflammatory reaction when injected into the skin.     

A Th2 chemokine, TARC, produced by keratinocytes may recruit CLA+CCR4+ lymphocytes into lesional atopic dermatitis skin

Atopic dermatitis is an inflammatory skin disease in which the inflammation is characterized by the influx of lymphocytes into the dermis. It is generally believed that atopic dermatitis is a Th2-type disease, i.e., the T lymphocytes produce interleukin-4, interleukin-5, interleukin-10, and interleukin-13, although it has become evident in recent years that the cytokine profile in the skin changes during the course of the disease towards a Th1-Th2 mixed cytokine profile (interferon-gamma, tumor necrosis factor alpha, and interleukin-2). The lymphocytes that home into the skin express cutaneous lymphocyte-associated antigen, and it has recently been shown that most of the lymphocytes in this population express the chemokine receptor CCR4. CCR4 is the receptor for the CC chemokine TARC (thymus and activation regulated chemokine), and this chemokine is expressed predominantly by keratinocytes in the basal layer of the epidermis of lesional atopic dermatitis skin in mice. In humans, however, it was shown to be expressed in the endothelial cells of the dermis. We have examined the peripheral blood mononuclear cells of atopic dermatitis patients for the expression of cutaneous lymphocyte-associated antigen and CCR4 and compared them with peripheral blood mononuclear cells from normal controls. We found that the proportion of CLA+CCR4+ lymphocytes is upregulated in atopic dermatitis patients. In addition we have examined skin biopsies of lesional and non-lesional skin from atopic dermatitis patients and found that the keratinocytes, but not the endothelial cells, produce TARC in the lesional but not in the nonlesional skin. To gain insight in the stimulatory mechanisms for TARC production in keratinocytes, as previously observed in mice, we cultured HaCaT cells and found that interferon-gamma and tumor necrosis factor alpha work synergistically to induce TARC production. These observations suggest that the induction of TARC production in keratinocytes plays an important role in the late phase skin invasion by CCR4+CLA+ Th2-type lymphocytes in atopic dermatitis.     

Thymus and activation regulated chemokine (TARC)/CCL17 and skin diseases

Thymus and activation-regulated chemokine (TARC)/CCL17 is constitutively expressed in the thymus and is produced by dendritic cells (DC), endothelial cells, keratinocytes (KC) and fibroblasts. TARC is designated a Th2 type chemokine since it binds to CCR4. We review the pathogenic role of TARC in skin diseases such as atopic dermatitis (AD), bullous pemphigoid (BP) and mycosis fungoides (MF) focusing on epidermal KC and Langerhans cells (LC), which are epidermal DC. We have determined that serum TARC levels sharply reflect the disease activity of AD, which is thought to be a Th2-dominant inflammatory skin disease especially in the acute phase. Serum TARC levels are also related to the disease activity of BP, which is a blistering autoimmune skin disease, and MF, which is a cutaneous T-cell lymphoma, but very high serum TARC levels are only seen in a limited number of various other skin diseases. TARC may be a useful laboratory marker for the diagnosis of AD, especially cases which are moderate to severe, and for the evaluation of disease activity of AD. IL-4 and TGF-beta1 downregulate TNF-alpha and IFN-gamma induced TARC production in the human KC cell line, HaCaT cells, while IL-4 upregulates, and IFN-gamma downregulates TARC production by mouse LC. Because TARC and its receptor CCR4 are believed to play important roles in the pathogenesis of AD, BP and MF, TARC and CCR4 may be possible future targets for therapy of these diseases.     

寻常型银屑病患者趋化因子受体7表达及其意义探讨

目的探讨趋化因子受体家族中CC趋化因子受体7(CCR7)在寻常型银屑病患者皮损及外周血T细胞上的表达情况。方法应用免疫组化和流式细胞分析的方法分别检测23例寻常型银屑病患者皮损和外周血T细胞表面CCR7的表达。结果与正常人皮肤相比,寻常型银屑病患者皮损中CCR7表达明显增高(P<0.01);通过流式细胞分析发现患者外周血T细胞表面CCR7表达也同样高于正常对照(P<0.01)。结论寻常型银屑病患者皮损和外周血中CCR7+记忆性淋巴细胞数量及分布异常可能与疾病的炎症维持密切相关。     

Role of the chemokine receptor CCR4 and its ligand thymus- and activation-regulated chemokine/CCL17 for lymphocyte recruitment in cutaneous lupus erythematosus

Skin-infiltrating T lymphocytes are thought to play a major role in the pathogenesis of cutaneous lupus erythematosus (CLE). In this study, we investigated the role of the chemokine receptor 4 (CCR4) and its ligand thymus- and activation-regulated chemokine (TARC/CCL17) for the recruitment of T cells in inflamed skin of patients with CLE. We found significant numbers of CCR4+ T lymphocytes in the skin of all patients with CLE. Interestingly, a subset of patients with disseminated scarring skin involvement were characterized by both lesional and circulating CD8+ T cells expressing CCR4. Destruction of epidermal and adnexal structures was histomorphologically associated with CCR4+ cytotoxic T cells invading basal layers of the epidermis where keratinocytes showed apoptotic death. The CCR4 ligand TARC/CCL17 was strongly expressed in skin lesions and elevated in the serum of CLE patients. The functional relevance of lymphocytic CCR4 expression could be confirmed by TARC/CCL17-specific in vitro migration assays. Our investigations suggest that CCR4 and TARC/CCL17 play a role in the pathophysiology of CLE. In particular, cytotoxic CD8+ T cells expressing CCR4 appear to be involved in scarring subtypes of CLE.     

IL-10 augments the IFN-gamma and TNF-alpha induced TARC production in HaCaT cells: a possible mechanism in the inflammatory reaction of atopic dermatitis

The CC-chemokine TARC is known to be a ligand for the CCR4 receptor which in turn is known to be expressed selectively on the Th(2)-subset of lymphocytes. Atopic dermatitis is generally believed to be a Th(2)-type disease, and TARC has been shown to be expressed in the skin lesions of a murine model of AD. IL-10 is an interleukine generally known for its ability to inhibit cytokine production, however it has been found to be highly expressed in the skin from AD patients. We show in this report that IL-10 is able to augment the TARC inducing effects of TNFalpha and IFNgamma in HaCaT cells, a property that may be important in the determination of the composition of the cells of the inflammation in the skin of AD patients. In addition, we show that the IL10 agonist IT 9302, a nona-peptide from the carboxylic end of IL-10, has the same effect on TARC production from HaCaT cells.     

卡介菌多糖核酸对特应性皮炎患者PBMC中TARC与CCR4表达的影响

目的检测卡介菌多糖核酸治疗前后特应性皮炎(AD)患者外周血胸腺和活化调节的趋化因子(TARC)与其相应受体CCR4的表达,以探讨其治疗特应性皮炎的相关机制。方法采用酶联免疫吸附试验检测45例AD患者卡介菌多糖核酸治疗前后血清中TARC水平;同时用流式细胞仪分析外周血中CCR4的表达。结果与治疗前(1169.1±106.5pg/mL)相比,卡介菌多糖核酸治疗后AD患者血清TARC(810.1±77.6pg/mL)显著降低(P<0.01);与治疗前(60.1±2.4)%相比,卡介菌多糖核酸治疗后AD患者外周血CCR4表达水平(54.6±2.2)%显著降低(P<0.01)。结论卡介菌多糖核酸可能通过降低TARC与CCR4,从而减少Th2细胞的募集、活化而发挥其治疗特应性皮炎的作用。     

Expression pattern of chemokine receptors and chemokine release in inflammatory erythroderma and Sézary syndrome

BACKGROUND: Erythroderma can be caused by inflammatory dermatoses or cutaneous T-cell lymphoma. Even if chemokines and their receptors are involved in the skin-selective lymphocyte recruitment, their role in inflammatory erythroderma is yet unclear. OBJECTIVE: To evaluate the chemokine release (TARC, MDC, IP-10) and to define the expression pattern of Th1- (CCR5, CXCR3) and Th2-related (CCR4) chemokine receptors in inflammatory erythroderma and Sézary syndrome (SS). MATERIALS AND METHODS: Flow cytometry has been carried out on both circulating and skin-infiltrating T lymphocytes; serum chemokine levels have been evaluated using ELISA techniques. RESULTS: CCR4, CCR5 and CXCR3 were expressed on about 40% of peripheral blood lymphocytes and on the majority of skin-infiltrating lymphocytes in the inflammatory erythroderma patients, whereas the leukemic CD4+CD26- subpopulation in SS was characterized by a high CCR4 expression without a concurrent increase in CCR5 or CXCR3. TARC, MDC and IP-10 serum levels were significantly increased in both erythrodermic and SS patients. CONCLUSIONS: Our results confirm that SS is a Th2 disorder with a selective expression of CCR4, whereas inflammatory erythroderma shares an overexpression of both Th1- and Th2-related chemokine receptors, suggesting an activation of different pathways driving reactive lymphocytes to the skin.     

雷公藤多甙对特应性皮炎患者PBMC中TARC与CCR4表达的影响

目的：检测雷公藤多甙对特应性皮炎患者外周血胸腺和活化调节趋化因子（TARC）与相应受体CCR4表达的影响。方法：分别采用酶联免疫吸附试验和流式细胞仪分析法检测外周血胸腺和活化调节趋化因子（TARC）与相应受体CCR4水平。结果：45例患者血清TARC治疗前（1120．1±102．4）pg／mL,与治疗后（790．2±75．8）ps／mL相比显著降低（P〈0．01）;患者外周血CCR4表达水平治疗前（60．2±2．3）％与治疗后（53．5±2．1）％相比,显著降低（P〈0．01）。结论：雷公藤多甙可能通过降低TARC与CCR4的表达从而减少Th2细胞的募集、活化而发挥其治疗特应性皮炎的作用。     

High level of thymus and activation-regulated chemokine in blister fluid and sera of patients with bullous pemphigoid

BACKGROUND: Bullous pemphigoid (BP) is an autoimmune blistering disease characterized by eosinophilia and high serum IgE levels. The accumulated evidence suggests that various cytokines are involved in the lesional skin of patients with BP. Recently, thymus and activation-regulated chemokine (TARC/CCL17), a CC chemokine, was identified as a selective chemoattractant for CC chemokine receptor 4 (CCR4)-expressing cells. OBJECTIVE: In this study, we examined the involvement of TARC in patients with BP. METHODS: We determined the fluid and serum TARC levels in patients with BP by enzyme-linked immunosorbent assay and compared the serum TARC levels with the eosinophil numbers in peripheral blood. We also compared the serum TARC levels in five patients with BP before and after they were treated. Moreover, we examined TARC, CCR4 and CXC chemokine receptor 3 (CXCR3) expression in the lesional skin of patients with BP by immunohistochemical procedures. Furthermore, we measured CCR4 positivity in CD4+ CD45RO+ cells of peripheral blood mononuclear cells (PBMCs) in patients with BP and healthy control subjects. RESULTS: The fluid TARC levels in patients with BP were significantly higher than those in blisters from burn patients or suction blisters of healthy control subjects. The serum TARC levels in patients with BP were also significantly higher than those in pemphigus vulgaris (PV) patients and healthy control subjects, and decreased after the treatment. The serum TARC levels in patients with BP significantly correlated with the eosinophil numbers in peripheral blood (r = 0.72, P < 0.002). Immunohistochemistry showed a strong reactivity of TARC in the epidermal keratinocytes (KCs) of BP. Moreover, both CCR4 and CXCR3 were expressed on the dermal infiltrating CD4+ T cells mainly beneath the bullae of patients with BP. Fluorescence-activated cell sorting analysis showed a higher percentage of CCR4 positivity in CD4+ CD45RO+ cells of PBMCs in patients with BP than that in healthy control subjects, while there was no significant difference of CXCR3 positivity in CD4+ CD45RO+ cells of PBMCs between patients with BP and healthy control subjects. CONCLUSIONS: These findings strongly suggest that TARC may be one of the important chemokines that are involved in the pathogenesis of BP.     

趋化性细胞因子受体CCR4和CXCR3在特应性皮炎患者外周血的表达

目的为研究特应性皮炎患者外周血趋化性细胞因子受体CCR4和CXCR3在特应性皮炎的发病过程中的作用。方法采用三色流式细胞仪测定20例特应性皮炎患者和30例健康对照者外周血趋化性细胞因子受体CCR4和CXCR3的表达水平。结果特应性皮炎患者外周血CCR4+CD4+T细胞的水平明显高于对照组(P<0.01);特应性皮炎患者外周血CCR4/CXCR3比率明显高于对照组P<0.01);特应性皮炎患者外周血CXCR3+CD4+T细胞的水平与对照组差异无统计学意义。结论趋化性细胞因子受体CCR4可能促进了Th2细胞从血液进入特应性皮炎患者炎症皮损。     

β趋化因子CCL20及其受体CCR6mRNA在寻常性银屑病患者皮损中的表达

目的探讨β趋化性细胞因子家族中CC趋化因子配体20(CCL20)及其受体CC趋化因子受体6(CCR6)mRNA在寻常性银屑病患者皮损中的表达情况.方法应用逆转录-聚合酶链式反应(RT-PCR)方法检测35例寻常性银屑病患者皮损和18例正常人皮肤中CCL20和CCR6mRNA的表达.结果与正常人皮肤相比,寻常性银屑病患者皮损中CCL20与CCR6mRNA的表达水平均明显增高(P＜0.001).结论寻常性银屑病患者皮损中CCL20和CCR6 mRNA表达水平的上调可能与银屑病的发病有关.     

Statins inhibit chemotactic interaction between CCL20 and CCR6 in vitro: possible relevance to psoriasis treatment

Psoriasis is a chronic IL-23/Th17 pathway-associated skin disease. An increased expression of lesional CCL20 can recruit CCR6+ Th17, and lesional cytokine milieu persistently activates keratinocytes to produce CCL20. Lipid-lowering drugs, statins, are known to possess immune-modulating functions. In this study, we explored an inhibitory effect of statins on CCL20/CCR6 interaction. We demonstrated that IL-1β, TNF-α, and IL-17A significantly increased CCL20 production from HaCaT cells. However, these increments were markedly inhibited by fluvastatin and simvastatin, but not by pravastatin. In the chemotaxis migration assay, pretreatment with fluvastatin and simvastatin inhibited the migration of human CD4+ T cells towards CCL20. However, the level of CCR6 surface expression in memory CD4+ T cells was not affected. Our results suggest that not all, but specific types of statins may be of benefit in alleviating psoriasis partially via interrupting CCL20/CCR6 chemotactic interaction, the mechanism which may eventually lessen the infiltration of Th17 cells.     

Enhanced CCR9 expression levels in psoriatic skin are associated with poor clinical outcome to infliximab treatment

Infliximab is an anti‐tumor necrosis factor (TNF)‐α antibody drug that suppresses TNF‐α and its associated inflammatory responses. Although infliximab therapy generally results in a 75% or greater improvement in the Psoriasis Area and Severity Index from baseline in psoriasis patients, there is the heterogeneity of therapeutic efficacy in psoriasis patients among patients of a similar PASI baseline score. However, there are few published reports about the predictors of the clinical response among psoriasis patients who undergo biologic therapies. We thus evaluated the possible existence of biologic markers that would indicate poor prognosis of infliximab using skin biopsy specimens. This was because we assumed that the inhibitors for upregulated chemokine/chemokine receptors in non‐responders may have the ability to reduce the occurrence of psoriatic eruptions. PCR array analyses identified that the levels of various chemokines and chemokine receptors were increased in non‐responders in comparison to responders. Immunohistochemical analyses revealed that upregulation of the CCR9 protein levels was not associated with the pretherapeutic PASI score, but with poor response to infliximab. Our results indicated that the expression levels of CCR9 in lesional skin may be a useful biologic marker of the clinical efficacy of infliximab therapy in psoriasis patients.     

Nickel-responding T cells are CD4+ CLA+ CD45RO+ and express chemokine receptors CXCR3, CCR4 and CCR10

BACKGROUND: Whereas T lymphocytes are widely accepted as effector cells determining the pathogenesis of allergic contact dermatitis, contradictory results have been found regarding the roles of different T-cell subsets. The use of various experimental models, involving long-term cultured T-cell lines or clones, may explain these contradictory results. OBJECTIVE: To investigate the involvement of distinct T-cell subsets in patients with nickel contact allergy. METHODS: Different T-cell subsets were directly isolated from peripheral blood mononuclear cells (PBMCs) of nickel-allergic patients, and their proliferative capacity, type-1 or type-2 cytokine secretion [measured by interferon (IFN)-gamma or interleukin (IL)-5 release] and phenotypical marker expression were analysed after stimulation with nickel. RESULTS: Only CD4+ CLA+ CD45RO+ and not CD8+ T cells proliferate and produce both type-1 (IFN-gamma) and type-2 (IL-5) cytokines in response to nickel. Moreover, cells expressing the marker CLA in combination with CD4, CD45RO or CD69 are increased after nickel-specific stimulation. Interestingly, in addition, CD45RA+ CLA+ cells showed an increased frequency after allergen-specific stimulation. Analysis of nickel-reactive T cells for expression of distinct chemokine receptors showed that both proliferative capacity and cytokine production are restricted to subsets expressing CXCR3, CCR4 but not CCR6. Fluorescence-activated cell sorting analysis of chemokine receptors expressed on nickel-stimulated T cells confirmed these results; a subset of T cells expressing CLA and CXCR3, CCR4 and, most importantly, CCR10 increased in response to allergen, while these CLA+ nickel-reactive T cells were all negative for CCR6. CONCLUSIONS: These findings demonstrate that freshly isolated nickel-reactive T cells can be characterized as CD4+ CLA+ memory T cells which express the chemokine receptors CXCR3, CCR4 and CCR10, but not CCR6.     

CC chemokine receptor 4 expression on peripheral blood CD4+ T cells reflects disease activity of atopic dermatitis

Recent studies indicate that Th1 and Th2 cells differ in their chemokine receptor expression and their responsiveness to various chemokines. Therefore, selective Th2 cell recruitment in Th2-predominant inflammatory diseases such as atopic dermatitis may be under the influence of some chemokines. It is reported that CC chemokine receptor (CCR) 4 is selectively expressed on Th2 cells whereas CXC chemokine receptor (CXCR) 3 is selectively expressed on Th1 cells. In this study we examined CCR4 and CXCR3 expression on peripheral blood CD4+ and CD8+ T cells obtained from adult atopic dermatitis subjects, and compared the results with those from patients with psoriasis vulgaris and healthy controls. CCR4 was preferentially expressed on CD4+ T cells from atopic dermatitis subjects and CXCR3 was preferentially expressed on CD4+ T cells from psoriasis vulgaris subjects. This CCR4 expression was prominent especially in severe atopic dermatitis subjects. CCR4 expression on CD4+ T cells in severe atopic dermatitis subjects decreased on improvement of disease activity. CD25 was preferentially expressed on CCR4+CD4+ T cells but not on CXCR3+CD4+ T cells in atopic dermatitis subjects. Cutaneous lymphocyte-associated antigen was also preferentially expressed on CCR4+CD4+ T cells but not on CXCR3+CD4+ T cells in atopic dermatitis subjects. CD4+ T cells in atopic dermatitis skin lesions were predominantly CCR4+ cells. Taken together, this study strongly indicates that CCR4+CD4+ T cells reflect disease activity and suggests that CCR4 expression is important for T cell infiltration into atopic dermatitis lesions. Thus, CCR4 may be a possible target for therapy of atopic dermatitis in the future.