Both Th1 and Th2 chemokines are elevated in sera of patients with autoimmune blistering diseases

Although chemokines are critical elements for the selective attraction and activation of various leukocyte subsets in the inflammatory process, there are few findings concerning T helper (Th) 1 or Th2 chemokines in autoimmune blistering disease (ABD). To determine whether serum levels of chemokines that are preferentially chemotactic for Th1 (monokine induced by IFN-γ (MIG/CXCL9)) and Th2 (thymus and activation regulated chemokine (TARC/CCL17) and macrophage derived chemokine (MDC/CCL22)) cells were elevated and whether they correlated with the clinical features in patients with ABD. Serum chemokine levels were examined using ELISA in patients with pemphigus vulgaris (PV, n=19), pemphigus foliaceous (PF, n=14), or bullous pemphigoid (BP, n=27) and normal controls (n=20). Serum MIG levels were significantly higher in patients with PV, PF, or BP than those in the control subjects. Serum levels of TARC and MDC were also significantly elevated in patients with PV, PF, or BP relative to the normal controls. Among the ABD subgroups, the levels of each chemokine tended to be higher in BP patients than in PV patients. Furthermore, serum TARC levels correlated positively with serum IgE levels in patients with ABD. Levels of TARC, MDC, and MIG were significantly decreased after treatment when the skin lesions disappeared in these patients. Furthermore, serum MIG levels correlated positively with serum levels of TARC and MDC in the ABD patients. These results suggest that both a Th1 chemoattractant MIG and Th2 chemoattractants, TARC and MDC, cooperatively play a role in the development of ABD.     

Macrophage-derived chemokine (MDC)/CCL22 produced by monocyte derived dendritic cells reflects the disease activity in patients with atopic dermatitis

BACKGROUNDS: Atopic dermatitis (AD) is a recurrent inflammatory skin disease characterized by high serum levels of IgE and Th2-type cytokines such as IL-4, IL-5 or IL-13. Chemokines attract leukocytes in inflamed tissues. We have previously found that thymus and activation regulated chemokine (TARC)/CCL17 and macrophage-derived chemokine (MDC)/CCL22 are highly secreted in the plasma levels of AD patients. Dendritic cells (DCs) are antigen-presenting cells that are divided into two subgroups including monocyte derived DCs (MoDCs) and plasmacytoid DCs (pDCs). OBJECTIVES: The aim of the study was to elucidate CCL17 and CCL22 production by MoDCs in AD patients, psoriasis vulgaris (PsV) patients and healthy controls (HC). METHODS: MoDCs were obtained from AD patients, PsV patients or HC and were cultured. In addition, the chemokine levels were measured in the supernatants. RESULTS: We found that the CCL22 levels produced by MoDCs in AD patients to be significantly higher than those of PsV patients and HC. There was a significant correlation between the CCL22 levels produced by MoDCs and the SCORAD index. No significant difference in the CCL17 levels produced by MoDCs was detected among AD patients, PsV patients or HC. Immunosuppressive drugs such as dexamethasone (Dex), tacrolimus and cyclosporine (Cys) inhibited the CCL22 production by MoDCs in the AD patients. CONCLUSION: These data suggest that the CCL22 level produced by MoDCs thus reflects the disease activity of AD and it may also play an important role regarding the production of CCL22 in the pathogenesis of AD.     

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.     

Nocturnal wrist movements are correlated with objective clinical scores and plasma chemokine levels in children with atopic dermatitis

BACKGROUND: Atopic dermatitis (AD) is a distressing disease associated with pruritus and sleep disturbance. Scratching due to pruritus is an important mechanism in the exacerbation of AD but is difficult to document in the home environment. OBJECTIVES: To evaluate whether nocturnal wrist activities, defined as average acceleration in the early hours of sleep, were correlated with components of the SCORing Atopic Dermatitis (SCORAD) index and various AD-associated chemokine markers. METHODS: Patients with AD aged under 18 years were recruited and the severity of eczema was assessed with the SCORAD index. Concentrations of plasma AD-associated chemokines [cutaneous T-cell attracting cytokine (CTACK); macrophage-derived chemokine (MDC); thymus and activation regulated chemokine (TARC)], interleukin (IL)-18, serum total IgE, and eosinophil counts were measured in these patients. Healthy children with noninflammatory and nonitchy skin conditions as well as healthy children of staff volunteers were recruited as controls. All children were instructed to wear the DigiTrac monitor on their dominant wrist before sleeping. The monitor was programmed to record limb motion between 22.00 and 08.00 h the following morning. RESULTS: Twenty-four Chinese children with AD (mean +/- SD age 12.6 +/- 3.7 years) and 15 normal children (mean +/- SD age 11.9 +/- 3.4 years) were recruited. The median (interquartile range) SCORAD was 54.8 (32.8-70.2). Plasma concentrations in pg mL(-1) of CTACK, MDC, TARC and IL-18 in the patients were 105 (92-172), 1648 (973-4214), 258 (100-850) and 415 (304-539), respectively. When compared with controls, most wrist activities occurred at frequencies between 1 and 3 Hz. These activities were most consistent over the first 3 h of sleeping and correlated significantly with disease severity, extent, intensity, and AD-associated chemokine markers CTACK, MDC and TARC. However, there was no significant correlation between wrist activities and the subjective symptom of pruritus or sleep loss. CONCLUSIONS: This is the first study to demonstrate that wrist activities, nonintrusively measured by the DigiTrac monitor at home, are closely correlated with the objective clinical scores and levels of peripheral blood chemokine markers for AD but not with the reported symptoms of pruritus or sleep loss. We propose that wrist activities between 1 and 3 Hz for the first 3 h are a good indicator of AD severity in children and should substitute for the pruritus and sleep-loss components of the SCORAD.     

Effect of an antiallergic drug (Olopatadine hydrochloride) on TARC/CCL17 and MDC/CCL22 production by PBMCs from patients with atopic dermatitis

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by the predominant infiltration of Th2-type cells in lesional skin. Thymus and activation-regulated chemokine (TARC/CCL17) and monocyte-derived chemokine (MDC/CCL22) are Th2-type cytokines, and it has been reported that serum CCL17 and CCL22 levels are associated with AD disease activity. Olopatadine hydrochloride (Olopatadine) is an antiallergic drug with selective histamine H(1) receptor antagonist activity. The effect of Olopatadine on chemokine production by peripheral blood mononuclear cells (PBMCs) in AD patients has not been completely elucidated. OBJECTIVES: This study was undertaken to clarify the effects of Olopatadine on CCL17 and CCL22 production by PBMCs from patients with AD during the treatment. METHODS: We measured plasma levels of CCL17, CCL22, IFNgamma, IL-12 and IL-18 in 15 patients with AD before and after treatment with oral Olopatadine (10 mg/day) for 4 weeks. We also examined disease activity using SCORAD index, eosinophil numbers in peripheral blood and serum levels of LDH. PBMCs from the patients were taken before and after the treatment and cultured with or without dust mite allergen extract (DME) for 3 or 5 days. CCL17, CCL22, IFNgamma, IL-12 and IL-18 levels in the supernatants of cultured PBMCs were measured. RESULTS: SCORAD index and eosinophil numbers in peripheral blood significantly decreased during treatment of AD patients with oral Olopatadine and topical corticosteroids for 4 weeks. The plasma levels of CCL17 and CCL22 significantly decreased after the treatment compared with before the treatment (p<0.05) and were significantly correlated with SCORAD index. PBMCs from AD patients taken after the treatment and cultured with DME for 5 days, showed significantly lower levels of CCL17 production than those taken before the treatment (p=0.018). PBMCs from AD patients taken after the treatment and cultured with DME for 5 days, also showed significantly lower levels of IFNgamma production than those taken before the treatment (p=0.012). CONCLUSION: Our data demonstrate that Olopatadine inhibits CCL17 and CCL22 production by PBMCs from AD patients, which are important regulators of Th2 recruitment in the skin.     

Case of atopic dermatitis concurrent with idiopathic thrombocytopenic purpura,whose serum thymus and activation‐regulated chemokine level remained undetectable

We report a 9‐year‐old Japanese female patient with atopic dermatitis associated with idiopathic thrombocytopenic purpura. She demonstrated high serum immunoglobulin (Ig)E and IgE specific to several environmental allergens, but extremely low serum thymus and activation‐regulated chemokine (TARC) levels regardless of the disease progression. This case suggests platelets as the main source of serum TARC.     

Expression and biological functions of the CCL5‐CCR5 axis in oral lichen planus

Oral lichen planus (OLP) is a chronic inflammatory oral mucosal disorder with T cell‐mediated immunological pathogenesis. C‐C motif chemokine ligand 5 (CCL5) and its receptor C‐C motif chemokine receptor 5 (CCR5) play important roles in the activation and recruitment of T cells. This study sought to explore the expression and biological functions of the CCL5‐CCR5 axis in OLP. We examined the expression of the CCL5‐CCR5 axis in the peripheral blood and oral tissue of healthy controls and patients with OLP using quantitative real‐time PCR, Simple Western assays, enzyme‐linked immunosorbent assay (ELISA) and immunohistochemistry. In addition, we investigated the effects of the CCL5‐CCR5 axis on the proliferation, apoptosis and migration of OLP T cells using Cell Counting Kit‐8 (CCK8) assay, flow cytometry and transwell assay. We found that the expression of the CCL5‐CCR5 axis was significantly elevated both in the peripheral blood and oral tissue of patients with OLP compared with healthy controls. CCL5 not only promoted OLP T‐cell proliferation and migration but also inhibited OLP T‐cell apoptosis. Moreover, CCR5 inhibition suppressed OLP T‐cell proliferation and migration, whereas OLP T‐cell apoptosis was promoted. In conclusion, our data suggest that the CCL5‐CCR5 axis may be closely related to the inflammatory infiltration of T cells in OLP.     

Serum levels of cutaneous T-cell attracting chemokine (CTACK) as a laboratory marker of the severity of atopic dermatitis in children

There are at least 13 scoring systems for the assessment of disease severity in atopic dermatitis (AD). Each system has its problems with interobserver and intraobserver variability. Cutaneous T-cell attracting chemokine (CTACK) is a skin-specific chemoattractant which may correlate with AD severity and obviate the issue of observer reliability. We evaluated whether serum CTACK concentrations were associated with the severity of AD in children according to the SCORing Atopic Dermatitis (SCORAD) index. Thirty-seven Chinese children with AD (23 boys, 14 girls; aged 1-11 years) and 13 controls were recruited. The median (interquartile range) overall SCORAD for AD patients was 29.7 (20.3-49.7). Serum concentrations of CTACK and two other atopy-related chemokines, macrophage-derived chemokine (MDC) and thymus and activation-regulated chemokine (TARC), were measured by sandwich enzyme immunoassay. There were significant correlations between SCORAD (r = 0.394, P = 0.016), its area (r = 0.528, P = 0.001) and intensity components (r = 0.429, P = 0.008) with serum levels of CTACK. The serum concentrations of inflammatory markers MDC and TARC also correlated with the CTACK concentrations (r = 0.618, P < 0.001, and r = 0.587, P = 0.001, respectively). Serum CTACK concentration appears to be a skin-specific objective marker that correlates with various clinical and laboratory parameters of AD.     

CC chemokines as potential immunologic markers correlated with clinical improvement of atopic dermatitis patients by immunotherapy

Please cite this paper as: CC chemokines as potential immunologic markers correlated with clinical improvement of atopic dermatitis patients by immunotherapy. Experimental Dermatology 2010; 19: 246–251. Abstract: Although immunotherapy is not accepted as a curative treatment for atopic dermatitis (AD), most studies have shown positive effects of immunotherapy on AD patients. The serum levels of CC chemokine ligand 17 (CCL17), CCL22 and CCL18 have been reported to be highly correlated with disease severity, which suggests important roles for CC chemokines in the pathogenesis of AD. Objective: The purpose of this study was to investigate the changes in clinical and immunologic markers before and after immunotherapy and to find which CC chemokines correlate with clinical improvement after immunotherapy with house dust mite (HDM) allergens in AD patients. Methods and Results: A total of 20 AD patients who were sensitized to HDM allergens through a skin‐prick test and Pharmacia CAP system were treated with subcutaneous immunotherapy using HDM allergens (treatment duration 12–60 months). Eczema area and severity index scores in 20 patients with AD decreased significantly after immunotherapy (P < 0.001). Serum total immunoglobulin E (IgE) and Dermatophagoides pteronyssinus‐specific IgE levels tended to decrease after treatment although this was not statistically significant, and the D. farinae‐specific IgE level showed no change. Serum CCL17, CCL22 and CCL18 levels decreased significantly from baseline after treatment (P = 0.043, 0.017 and <0.001, respectively). The percentage reductions in serum CCL17 and CCL22 level were significantly correlated with reductions in disease severity (P = 0.007, R² = 0.301 and P = 0.037, R² = 0.177, respectively). Conclusion: We suggest that CCL17 and CCL22 are good immunological marker candidates that can be used to assess clinical improvement after immunotherapy in AD patients.     

Serum mucosa-associated epithelial chemokine (MEC/CCL28) in atopic dermatitis: a specific marker for severity

Background Mucosa‐associated epithelial chemokine (MEC; CCL28) is considered to be pivotal in mediating the migration of CC chemokine receptor 3‐ and 10‐ (CCR3‐ and CCR10)‐expressing, skin‐homing, memory, cutaneous lymphocyte‐associated antigen‐positive (CLA⁺) T cells. CCL28 is selectively and continuously expressed by epidermal keratinocytes, but highly upregulated in inflammatory skin diseases, such as atopic dermatitis (AD). Aim This controlled longitudinal study was designed to evaluate the expression of CCL28 in serum in childhood AD and bronchial asthma (BA), and its possible relationship to disease severity and activity. Methods Serum CCL28 levels were measured in 36 children with AD, 23 with BA, 14 with both conditions, and 21 healthy age‐ and sex‐matched controls. Sixteen patients in the AD group were followed up and resampled for serum CCL28 after clinical remission. Serum CCL28 levels were correlated with some AD disease activity and severity variables. Results Serum CCL28 levels in AD, whether during flare [median, 1530 pg/mL; mean ± standard deviation (SD) = 1590.4 ± 724.3 pg/mL] or quiescence (median, 1477 pg/mL; mean ± SD = 1575.2 ± 522.1 pg/mL), were significantly higher than those in healthy children (median, 301 pg/mL; mean ± SD = 189.6 ± 92.8 pg/mL); however, the levels during flare and quiescence were statistically comparable. The serum levels in BA (median, 340 pg/mL; mean ± SD = 201.6 ± 109.5 pg/mL) were significantly lower than those in the AD group, and comparable with those in healthy controls. Serum CCL28 levels in severe AD were significantly higher than those in mild and moderate cases, and correlated positively with the calculated severity scores [Leicester Sign Score (LSS) and Scoring Atopic Dermatitis (SCORAD)]. CCL28 levels during the exacerbation of AD were positively correlated with the corresponding values during remission, the peripheral absolute eosinophil counts, and serum lactate dehydrogenase levels. Serum CCL28 levels were not correlated with the serum total immunoglobulin E values in AD. Conclusions Our data reinforce the concept that CCL28 might contribute to the pathogenesis of AD, probably through the selective migration and infiltration of effector/memory T‐helper‐2 cells in the skin. CCL28 may also represent an objective prognostic marker for disease severity. Further studies may pave the way for CCL28 antagonism among adjuvant therapeutic strategies.     

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.     

Potential preventive effects of proactive therapy on sensitization in moderate to severe childhood atopic dermatitis: A randomized,investigator‐blinded,controlled study

Proactive therapy for atopic dermatitis (AD) effectively prevents exacerbation. However, its role in preventing subsequent sensitization to allergens has not been prospectively studied. We investigated whether proactive therapy for AD can effectively impact immunological parameters in a randomized, investigator‐blinded, parallel group study. Thirty patients aged 3 months to 7 years with moderate to severe AD who had undergone an AD educational program were allocated to a proactive treatment group or a reactive treatment group. During the disease control period, patients in the proactive group performed intermittent preventive application of topical corticosteroid for 1 year. Changes in the severity scoring, quality of life measures and immunological parameters (serum thymus and activation regulated chemokine [TARC], total immunoglobulin E [IgE] and house dust mite‐specific IgE levels) were evaluated and compared between the proactive and reactive treatment groups. Although the average topical corticosteroid ointment use per day in both groups was not significantly different, the severity and quality of life scores were significantly lower in the proactive group than in the reactive group at the final visit. In addition, compared with baseline levels, serum TARC levels remained significantly lower during proactive therapy, while house dust mite‐specific IgE levels were significantly increased only in the reactive group. The results suggest that in addition to controlling the severity of AD, intermittent preventive administration of topical corticosteroids may prevent an increase in aeroallergen‐specific IgE levels in patients with childhood AD. The use of TARC levels as a biomarker for AD remission is also supported.     

The crucial role of IL‐22 and its receptor in thymus and activation regulated chemokine production and T‐cell migration by house dust mite extract

House dust mite (HDM) is known as one of the factors that causes atopic dermatitis (AD). Interleukin (IL)‐22 and thymus and activation regulated chemokine (TARC) are related to skin inflammatory disease and highly expressed in AD lesions. However, the effects of HDM on IL‐22 production in T cells and on TARC production and IL‐22Rα receptor expression in keratinocytes are unknown. To identify the role of HDM in keratinocytes and T cells, we investigated IL‐22Rα expression and TARC production in the human keratinocyte cell line HaCaT and IL‐22 production in T cells treated with HDM extract as well as their roles in HDM‐induced skin inflammation. HDM extract not only increased IL‐22Rα expression and TARC production in HaCaT but also enhanced IL‐22, tumor necrosis factor (TNF)‐α and interferon (IFN)‐γ production in T cells. The HDM extract‐induced IL‐22 from T cells significantly increased the production of IL‐1α, IL‐6 and TARC in HaCaT cells. In addition, we found that TARC produced in HDM extract‐treated HaCaT induced T‐cell recruitment. These results suggest that there is a direct involvement of HDM extract‐induced IL‐22 in TARC production and T‐cell migration. Taken together, TARC production in HaCaT through the interaction between IL‐22 and IL‐22Rα facilitates T‐cell migration. These data show one of the reasons for inflammation in the skin lesions of AD patients.     

Reciprocal regulation of thymus and activation-regulated chemokine/macrophage-derived chemokine production by interleukin (IL)-4/IL-13 and interferon-gamma in HaCaT keratinocytes is mediated by alternations in E-cadherin distribution

Keratinocytes produce many cytochemokines that are involved in the pathogenesis of skin disorders. In particular, the CC chemokines thymus and activation-regulated chemokine (TARC)/macrophage-derived chemokine (MDC) play an important role in the infiltration of Th2 cells. This study was undertaken to examine the regulatory effects of interleukin (IL)-4, IL-13, and interferon (IFN)-gamma on TARC/MDC production in the human keratinocyte cell line HaCaT. HaCaT cells spontaneously secrete TARC and MDC. The production of TARC/MDC was downregulated by IL-4/IL-13, whereas it was upregulated by IFN-gamma. To explore these regulatory mechanisms, we investigated the capacity of cytokines to regulate expression of several adhesion molecules that may affect TARC/MDC production. Of the adhesion molecules examined, the constitutive surface expression of E-cadherin was downregulated by IL-4/IL-13, but was upregulated by IFN-gamma. Moreover, disruption of the homophilic adherence of E-cadherin by anti-E-cadherin antibody or calcium chelation abolished the production of TARC/MDC. We further examined the distribution of the adherens junction complex composed of E-cadherin, alpha-catenin, beta-catenin, and gamma-catenin. IL-4/IL-13 decreased the levels of membrane staining for adherens junction proteins, whereas IFN-gamma increased membrane staining. Taken together, these results suggest that IL-4/IL-13 and IFN-gamma induce alternations in the distribution of adherens junctions in a different fashion and thereby contribute to the reciprocal regulation of TARC/MDC production.     

Induction of cytokine (interleukin-1alpha and tumor necrosis factor-alpha) and chemokine (CCL20, CCL27, and CXCL8) alarm signals after allergen and irritant exposure

The immune system is called into action by alarm signals generated from injured tissues. We examined the nature of these alarm signals after exposure of skin residential cells to contact allergens (nickel sulfate and potassium dichromate) and a contact irritant [sodium dodecyl sulfate (SDS)]. Nickel sulfate, potassium dichromate, and SDS were applied topically to the stratum corneum of human skin equivalents. A similar concentration-dependent increase in chemokine (CCL20, CCL27, and CXCL8) secretion was observed for all three chemicals. Exposure to nickel sulfate and SDS was investigated in more detail: similar to chemokine secretion, no difference was observed in the time- and concentration-dependent increase in pro-inflammatory cytokine [interleukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha)] secretion. Maximal increase in IL-1alpha secretion occurred within 2 h after exposure to both nickel sulfate and SDS and prior to increased chemokine secretion. TNF-alpha secretion was detectable 8 h after chemical exposure. After allergen or irritant exposure, increased CCL20 and CXCL8, but not CCL27, secretion was inhibited by neutralizing human antibodies to either IL-1alpha or TNF-alpha. Our data show that alarm signals consist of primary and secondary signals. IL-1alpha and TNF-alpha are released as primary alarm signals, which trigger the release of secondary chemokine (CCL20 and CXCL8) alarm signals. However, some chemokines, for example, CCL27 can be secreted in an IL-1alpha and TNF-alpha independent manner. Our data suggest that skin residential cells respond to both allergen and irritant exposure by releasing mediators that initiate infiltration of immune responsive cells into the skin.     

Expression of the T-helper 2-specific chemokine receptor CCR4 on CCR10-positive lymphocytes in atopic dermatitis skin but not in psoriasis skin

BACKGROUND: Atopic dermatitis (AD) and psoriasis are inflammatory skin diseases. AD is generally perceived as a T-helper (Th) 2-dominated disease whereas psoriasis is a Th1-dominated disease. The chemokine cutaneous T-cell attracting chemokine (CTACK) and its receptor CCR10 attract skin-homing lymphocytes to inflamed skin, suggesting that CCR10+ cells in AD and psoriasis should be of Th2 and Th1 type, respectively. The chemokine receptor CCR4 is expressed selectively on Th2 lymphocytes and its ligand thymus and activation-regulated chemokine (TARC) is upregulated in AD lesions, suggesting that the CCR10+ cells in AD lesions should also express CCR4. OBJECTIVES: To examine the coexpression of CCR10 and CCR4 on skin-invading lymphocytes in AD and psoriasis lesions as well as the Th1/Th2 cytokine expression of the CCR10+ lymphocytes. METHODS: Skin biopsies from AD and psoriasis patients were double stained with antibodies against CCR10-CCR4, CCR10-CCR5, CCR10-interleukin (IL)-2 and CCR10-IL-4. RESULTS: The CCR10+ cells in AD showed a mixed IL-2/IL-4 expression pattern, and a minor proportion expressed CCR4, whereas a large proportion of the CCR4+ cells did not express CCR10. In psoriasis the CCR10+ cells only expressed IL-2, and no CCR4 expression was detected. CONCLUSIONS: The CCR10+ lymphocytes invading the skin in AD and psoriasis have different Th1/Th2 profiles, as measured by both their cytokine and chemokine receptor expression. This suggests that the CCR10+ subpopulation of lymphocytes is made up of different Th1/Th2 subsets. However, the Th1/Th2 lymphocytes of AD and psoriasis were either CCR10+ or CCR10-, suggesting that both the Th1 and Th2 subpopulation can be subdivided further. CCR4 was found only in AD skin and on both CCR10+ and CCR10- cells, supporting the hypothesis of TARC and CTACK as being independent lymphocyte-attracting chemokines in AD.     

TGF-beta1-mediated regulation of thymus and activation-regulated chemokine (TARC/CCL17) synthesis and secretion by HaCaT cells co-stimulated with TNF-alpha and IFN-gamma

Thymus and activation-regulated chemokine (TARC/CCL17) contributes not only to the recruitment of leukocytes, but is also involved in immune disorders, such as atopic dermatitis (AD) and bronchial asthma. We have previously reported that the levels of TARC were high in patients with AD and that lesional epidermis were strongly immunoreactive for TARC. In this paper, the effects of transforming growth factor (TGF)-beta(1) on the expression of TARC/CCL17 were examined in HaCaT cells, a human keratinocytes (KCs) cell line, co-stimulated with TNF-alpha and IFN-gamma. We found that TGF-beta(1) down-regulated the TARC synthesis and secretion of HaCaT cells co-stimulated with TNF-alpha and IFN-gamma in a dose-dependent manner. TGF-beta(1) at a concentration of 10ng/ml maximally inhibited this secretion. Northern blot analysis showed a similar inhibitory effect of TGF-beta(1) on TARC mRNA expression by HaCaT cells. The TGF-beta(1)-induced down-regulation of TARC/CCL17 in HaCaT cells suggests that TGF-beta(1) might regulate the TARC-related inflammatory processes, which may be important for understanding the pathogenesis of allergic diseases.     

Determination of thymus and activation-regulated chemokine (TARC)-contents in scales of atopic dermatitis

BACKGROUND: Thymus and activation-regulated chemokine (TARC) is a cytokine which selectively controls the migration of type 2-helper T lymphocytes into inflammatory lesions, and the serum level is strongly associated with disease severity of atopic dermatitis (AD). OBJECTIVE: To examine the role of TARC in the pathogenesis of AD, we determined TARC-contents in the scales obtained from lesional skin of the patients with AD. RESULTS: High amount of TARC was detected in the scales of lesional skin obtained from the patients with AD, and the amount was well correlated with the serum IgE levels but not with the blood eosinophil counts. The TARC-content in the lesional scales was not correlated with a-431C/T polymorphism of TARC promotor gene, suggesting other regulating mechanisms in TARC production in the lesion. CONCLUSION: High amount of TARC is produced in the kesion of AD, and analysis of cytokine content in lesional scales may provide some tools to clarify the pathogenesis of AD.     

Thymus and activation-regulated chemokine (TARC)/CC chemokine ligand (CCL) 17 accelerates wound healing by enhancing fibroblast migration

Background Some chemokines are known to accelerate wound healing. However, there has been no report on the relationship between Thymus and activation‐regulated chemokine (TARC)/CC chemokine ligand (CCL) 17 and wound healing. The purpose of this study was to determine whether CCL17 enhances response to cutaneous injury. Methods We made a full‐thickness dorsal wound in transgenic (Tg) mice, in which CCL17 was overexpressed and in control mice. Wound size was compared over the course of time. We evaluated the effect of CCL17 on fibroblast migration by a Boyden chamber assay and a scratch wound assay. Results Wound closure in Tg mice was more accelerated than in control mice. CCL17 enhanced nerve growth factor (NGF) production by 2B4, which is mouse T cell hybridoma. Further, in the wound area of Tg mice, the number of CCR4⁺ fibroblasts, CCR4⁺ lymphocytes and mast cells was increased compared to control mice, as was the number of NGF⁺ lymphocytes around the wound area. In vitro assay, CCL17 was shown to enhance the migration of fibroblasts. Conclusion These results suggest that CCL17 accelerates wound healing, mainly by enhancing fibroblast migration, and possibly by increasing NGF⁺ lymphocytes and mast cells, which have independently been reported to enhance wound healing.