CCR4 memory CD4+ T lymphocytes are increased in peripheral blood and lesional skin from patients with atopic dermatitis

Topical application of a CCL22-binding aptamer suppresses contact allergy

Allergic contact dermatitis is a prevalent occupational disease with limited therapeutic options. The chemokine CCL22, a ligand of the chemokine receptor CCR4, directs the migration of immune cells. Here, it is shown that genetic deficiency of CCL22 effectively ameliorated allergic reactions in contact hypersensitivity (CHS), a commonly used mouse model of allergic contact dermatitis. For the pharmacological inhibition of CCL22, DNA aptamers specific for murine CCL22 were generated by the systematic evolution of ligands by exponential enrichment (SELEX). Nine CCL22-binding aptamers were initially selected and functionally tested in vitro. The 29-nt DNA aptamer AJ102.29m profoundly inhibited CCL22-dependent T cell migration and did not elicit undesired Toll-like receptor-dependent immune activation. AJ102.29m efficiently ameliorated CHS in vivo after systemic application. Moreover, CHS-associated allergic symptoms were also reduced following topical application of the aptamer on the skin. Microscopic analysis of skin treated with AJ102.29m ex vivo demonstrated that the aptamer could penetrate into the epidermis and dermis. The finding that epicutaneous application of the aptamer AJ102.29m in a cream was as effective in suppressing the allergic reaction as intraperitoneal injection paves the way for therapeutic use of aptamers beyond the current routes of systemic administration.

Clinical and molecular effects of oral CCR4 antagonist RPT193 in atopic dermatitis: A Phase 1 study

BACKGROUND

RPT193 is an orally administered small molecule antagonist of the human C-C motif chemokine receptor 4 (CCR4) that inhibits the migration and downstream activation of T-helper Type 2 (Th2) cells. We investigated single- and multiple-ascending doses of RPT193 in healthy subjects, and multiple doses of RPT193 in subjects with moderate-to-severe atopic dermatitis (AD).

METHODS

This was a first-in-human randomized, placebo-controlled Phase 1a/1b monotherapy study (NCT04271514) to evaluate the safety, tolerability, pharmacokinetics, pharmacodynamics, and CCR4 surface receptor occupancy in eligible healthy subjects and subjects with moderate-to-severe AD. Clinical efficacy and skin biomarker effects of RPT193 monotherapy were assessed as exploratory endpoints in AD subjects.

RESULTS

In healthy (n = 72) and AD subjects (n = 31), once-daily RPT193 treatment was generally well tolerated, with no serious adverse events reported and all treatment-emergent adverse events reported as mild/moderate. In AD subjects, numerically greater improvements in clinical efficacy endpoints were observed with RPT193 monotherapy versus placebo up to the end of the treatment period (Day 29), with statistically significant improvement, compared to Day 29 and placebo, observed 2 weeks after the end of treatment (Day 43) on several endpoints (p < .05). Moreover, significant changes in the transcriptional profile were seen in skin biopsies of RPT193-treated versus placebo-treated subjects at Day 29, which were also significantly correlated with improvements in clinical efficacy measures.

CONCLUSIONS

To our knowledge, this is the first clinical study with an oral CCR4 antagonist that showed clinical improvement coupled with modulation of the cutaneous transcriptomic profile in an inflammatory skin disease.

Complete Rescue of HTLV-1p12KO Infectivity by Depletion of Monocytes Together with NK and CD8+ T Cells

The transient depletion of monocytes alone prior to exposure of macaques to HTLV-1 enhances both HTLV-1WT (wild type) and HTLV-1p12KO (Orf-1 knockout) infectivity, but seroconversion to either virus is not sustained over time, suggesting a progressive decrease in virus expression. These results raise the hypotheses that either HTLV-1 persistence depends on a monocyte reservoir or monocyte depletion provides a transient immune evasion benefit. To test these hypotheses, we simultaneously depleted NK cells, CD8+ T cells, and monocytes (triple depletion) prior to exposure to HTLV-1WT or HTLV-1p12KO. Remarkably, triple depletion resulted in exacerbation of infection by both viruses and complete rescue of HTLV-1p12KO infectivity. Following triple depletion, we observed rapid and sustained seroconversion, high titers of antibodies against HTLV-1 p24Gag, and frequent detection of viral DNA in the blood and tissues of all animals when compared with depletion of only CD8+ and NK cells, or monocytes alone. The infection of macaques with HTLV-1WT or HTLV-1p12KO was associated with higher plasma levels of IL-10 after 21 weeks, while IL-6, IFN-γ, IL-18, and IL-1β were only elevated in animals infected with HTLV-1WT. The repeat depletion of monocytes, NK, and CD8+ cells seven months following the first exposure to HTLV-1 did not further exacerbate viral replication. These results underscore the contribution of monocytes in orchestrating anti-viral immunity. Indeed, the absence of orf-1 expression was fully compensated by the simultaneous depletion of CD8+ T cells, NK cells, and monocytes, underlining the primary role of orf-1 in hijacking host immunity.

Establishment of an experimental model of ovalbumin-induced atopic dermatitis in canines

Introduction

A reliable standard model is required to evaluate the efficacy of new drugs for companion animals, especially dogs. Canine atopic dermatitis (cAD), also known as allergic inflammatory skin disease, is a common condition. Currently, the house dust mite animal model is used in the research of cAD; however, this model exhibits significant individual variation and is difficult to standardize. In this study, we used ovalbumin as an antigen to sensitize and stimulate dogs, thereby establishing a stable model mimicking the T-helper 2 (Th2) response seen in cAD. Our objective was to create a cAD model that could be employed to evaluate the efficacy of novel drugs and mimic the Th2 dominant allergic response observed in the pathogenesis of atopic dermatitis of dogs.

Methods

In this study, six beagles were used. Normal saline was applied to two animals, and ovalbumin to four, on their dorsal skin.

Results

The ovalbumin-treated groups exhibited clinical cAD symptoms, such as pruritus and erythema. Moreover, plasma levels of the cAD markers immunoglobulin E and CCL17 chemokine were higher in the ovalbumin-treated group than in the vehicle control group. The skin thickness of the epidermis was significantly increased in the ovalbumin-treated group, with infiltration of inflammatory cells observed in the thickened dermis region. In conclusion, treatment of canine skin with an optimal concentration of ovalbumin induced typical cAD-like symptoms, and histological and molecular analyses confirmed an enhanced Th2-related immune response.

Conclusion

Therefore, we successfully established a suitable Th2-dominant response mimicking cAD, which will facilitate targeted research of atopic dermatitis in dogs.

Nicotinamide mononucleotide impacts HIV-1 infection by modulating immune activation in T lymphocytes and humanized mice

BACKGROUND

HIV-1-associated immune activation drives CD4+ T cell depletion and the development of acquired immunodeficiency syndrome. We aimed to determine the role of nicotinamide mononucleotide (NMN), the direct precursor of nicotinamide adenine dinucleotide (NAD) co-enzyme, in CD4+ T cell modulation during HIV-1 infection.

METHODS

We examined HIV-1 integrated DNA or transcribed RNA, intracellular p24 protein, and T cell activation markers in CD4+ T cells including in vitro HIV-1-infected cells, reactivated patient-derived cells, and in HIV-1-infected humanized mice, under NMN treatment. RNA-seq and CyTOF analyses were used for investigating the effect of NMN on CD4+ T cells.

FINDINGS

We found that NMN increased the intracellular NAD amount, resulting in suppressed HIV-1 p24 production and proliferation in infected CD4+ T cells, especially in activated CD25+CD4+ T cells. NMN also inhibited CD25 expression on reactivated resting CD4+ T cells derived from cART-treated people living with HIV-1 (PLWH). In HIV-1-infected humanized mice, the frequency of CD4+ T cells was reconstituted significantly by combined cART and NMN treatment as compared with cART or NMN alone, which correlated with suppressed hyperactivation of CD4+ T cells.

INTERPRETATION

Our results highlight the suppressive role of NMN in CD4+ T cell activation during HIV-1 infection. It warrants future clinical investigation of NMN as a potential treatment in combination with cART in PLWH.

FUNDING

This work was supported by the Hong Kong Research Grants Council Theme-Based Research Scheme (T11-706/18-N), University Research Committee of The University of Hong Kong, the Collaborative Research with GeneHarbor (Hong Kong) Biotechnologies Limited and National Key R&D Program of China (Grant2021YFC2301900).

The extrinsic factors important to the homeostasis of allergen-specific memory CD4 T cells

Memory T cells, which are generated after the primary immune response to cognate antigens, possess unique features compared to naïve or effector T cells. These memory T cells are maintained for a long period of time and robustly reactivate in lymphoid or peripheral tissues where they re-encounter antigens. Environments surrounding memory T cells are importantly involved in the process of the maintenance and reactivation of these T cells. Although memory T cells are generally believed to be formed in response to acute infections, the pathogenesis and persistence of chronic inflammatory diseases, including allergic diseases, are also related to the effector functions of memory CD4 T cells. Thus, the factors involved in the homeostasis of allergen-specific memory CD4 T cells need to be understood to surmount these diseases. Here, we review the characteristics of allergen-specific memory CD4 T cells in allergic diseases and the importance of extrinsic factors for the homeostasis and reactivation of these T cells in the view of mediating persistence, recurrence, and aggravation of allergic diseases. Overall, this review provides a better understanding of memory CD4 T cells to devise effective therapeutic strategies for refractory chronic inflammatory diseases.

Hypersensitivity to mosquito bites: A versatile Epstein-Barr virus disease with allergy, inflammation, and malignancy

Hypersensitivity to mosquito bites (HMB) is a rare disease characterized by transient intense skin reaction and systemic inflammation. Clinical presentation of HMB resembles other mosquito allergic responses, and it can also be difficult to clinically distinguish HMB from other severe allergic reactions. However, a distinctive pathophysiology underlies HMB. HMB belongs to a category of Epstein-Barr virus (EBV)-associated natural killer (NK) cell lymphoproliferative disorders (LPD). Hence, HMB may progress to systemic diseases, such as hemophagocytic lymphohistiocytosis, chronic active EBV disease, and EBV-associated malignancies. A triad of elevated serum IgE, NK lymphocytosis, and detection of EBV DNA in peripheral blood is commonly observed, and identification of EBV-infected NK cells usually facilitates the diagnosis. However, the effective treatment is limited, and its precise etiology remains unknown. Local CD4+ T cell proliferation triggered by mosquito bites appears to help induce EBV reactivation and EBV-infected NK-cell proliferation. These immunological interactions may explain the transient HMB signs and symptoms and the disease progression toward malignant LPD. Further research to elucidate the mechanism of HMB is warranted for better diagnosis and treatment of HMB and other forms of EBV-associated LPD.

Exophilin-5 regulates allergic airway inflammation by controlling IL-33-mediated Th2 responses

A common variant in the RAB27A gene in adults was recently found to be associated with the fractional exhaled nitric oxide level, a marker of eosinophilic airway inflammation. The small GTPase Rab27 is known to regulate intracellular vesicle traffic, although its role in allergic responses is unclear. We demonstrated that exophilin-5, a Rab27-binding protein, was predominantly expressed in both of the major IL-33 producers, lung epithelial cells, and the specialized IL-5 and IL-13 producers in the CD44hiCD62LloCXCR3lo pathogenic Th2 cell population in mice. Exophilin-5 deficiency increased stimulant-dependent damage and IL-33 secretion by lung epithelial cells. Moreover, it enhanced IL-5 and IL-13 production in response to TCR and IL-33 stimulation from a specific subset of pathogenic Th2 cells that expresses a high level of IL-33 receptor, which exacerbated allergic airway inflammation in a mouse model of asthma. Mechanistically, exophilin-5 regulates extracellular superoxide release, intracellular ROS production, and phosphoinositide 3-kinase activity by controlling intracellular trafficking of Nox2-containing vesicles, which seems to prevent the overactivation of pathogenic Th2 cells mediated by IL-33. This is the first report to our knowledge to establish the significance of the Rab27-related protein exophilin-5 in the development of allergic airway inflammation, and provides insights into the pathophysiology of asthma.

Solanum tuberosum L. cv Hongyoung extract inhibits 2,4‑dinitrochlorobenzene‑induced atopic dermatitis in NC/Nga mice

Solanum tuberosum L. cv Hongyoung (SH) is a widely consumed anthocyanin-rich food and medicinal plant, which possesses anti-inflammatory and anti-allergic activities. The present study aimed to examine the inhibitory effects of SH extract on atopic dermatitis (AD)-like skin lesions induced by the topical application of 2,4-dinitrochlorobenzene (DNCB) in NC/Nga mice. SH extract was orally administered to the DNCB-treated NC/Nga mice. The anti-AD effects of SH extract were examined by measuring symptom severity; ear thickness; scratching behavior; serum levels of immunoglobulin (Ig)E; T-helper (Th)1, Th2 and Th17 cytokine levels in the spleen; mRNA expression levels of inflammatory cytokines and chemokines; and tissue infiltration of inflammatory cells. The results demonstrated that SH extract inhibited the development of AD-like lesions, and reduced IgE levels and the production of cytokines. Furthermore, SH extract significantly suppressed the expression of AD-associated mRNAs in lesional skin. Histological alterations in the AD-like lesions were visualized using hematoxylin and eosin, and toluidine blue staining in the DNCB-treated group; the alterations were attenuated following SH treatment. In addition, thickening of the epidermis and accumulation of inflammatory cells in the DNCB-treated mice were suppressed by SH treatment. These results suggested that SH extract may suppress the development of AD symptoms through modulation of the Th1 and Th2 responses.

Frequent occurrence of T cell-mediated late reactions revealed by atopy patch testing with hypoallergenic rBet v 1 fragments

Background

Late allergic reactions are common in the course of allergen-specific immunotherapy and even occur with allergy vaccines with reduced IgE reactivity.

Objective

We sought to study atopy patch test (APT) reactions and T-cell responses to the recombinant birch pollen allergen Bet v 1 and recombinant hypoallergenic T-cell epitope–containing Bet v 1 fragments in patients with birch pollen allergy with and without atopic dermatitis (AD).

Methods

A clinical study was conducted in 15 patients with birch pollen allergy with AD (group 1), 5 patients with birch pollen allergy without AD (group 2), 5 allergic patients without birch pollen allergy (group 3), and 5 nonallergic subjects (group 4) by performing skin prick tests and APTs with rBet v 1 and hypoallergenic rBet v 1 fragments. T-cell, cutaneous lymphocyte antigen (CLA)⁺ and CCR4⁺ T-cell and cytokine responses were studied by thymidine uptake, carboxyfluorescein diacetate succinimidyl ester staining, and Luminex technology, respectively.

Results

rBet v 1 and hypoallergenic rBet v 1 fragments induced APT reactions in not only most of the patients with birch pollen allergy with AD (11/15) but also in most of those without AD (4/5). Patients with birch pollen allergy with AD had higher Bet v 1–specific proliferation of CLA⁺ and CCR4⁺ T cells compared with patients with birch pollen allergy without AD. There were no differences in Bet v 1–specific CLA⁺ and CCR4⁺ proliferation and cytokine secretion in patients with and without APT reactions.

Conclusion

Hypoallergenic rBet v 1 fragments induce T cell–dependent late reactions not only in patients with birch pollen allergy with AD but also in those without AD, which can be determined based on APT results but not based on in vitro parameters.

The Role of Invariant Natural Killer T Cells in Dendritic Cell Licensing, Cross-Priming, and Memory CD8(+) T Cell Generation

New vaccination strategies focus on achieving CD8⁺ T cell (CTL) immunity rather than on induction of protective antibody responses. While the requirement of CD4⁺ T (Th) cell help in dendritic cell (DC) activation and licensing, and in CTL memory induction has been described in several disease models, CTL responses may occur in a Th cell help-independent manner. Invariant natural killer T cells (iNKT cells) can substitute for Th cell help and license DC as well. iNKT cells produce a broad spectrum of Th1 and Th2 cytokines, thereby inducing a similar set of costimulatory molecules and cytokines in DC. This form of licensing differs from Th cell help by inducing other chemokines, while Th cell-licensed DCs produce CCR5 ligands, iNKT cell-licensed DCs produce CCL17, which attracts CCR4⁺ CD8⁺ T cells for subsequent activation. It has recently been shown that iNKT cells do not only enhance immune responses against bacterial pathogens or parasites but also play a role in viral infections. The inclusion of iNKT cell ligands in influenza virus vaccines enhanced memory CTL generation and protective immunity in a mouse model. This review will focus on the role of iNKT cells in the cross-talk with cross-priming DC and memory CD8⁺ T cell formation.

Thymic stromal lymphopoietin signaling in CD4(+) T cells is required for TH2 memory

BACKGROUND

Thymic stromal lymphopoietin (TSLP) is a key factor in the development of allergic asthma. Numbers of TH2 memory cells gradually increase in allergic patients with the progression of disease and persist in the lungs during remission, although the mechanism is not clear.

OBJECTIVE

We sought to define the role of TSLP in TH2 memory cell generation and maintenance in vivo.

METHODS

Adoptive transfer of wild-type and thymic stromal lymphopoietin receptor (TSLPR)-deficient ovalbumin-specific CD4(+) T cells before TH2 sensitization was used to define T cell-specific TSLP effects. Atopic dermatitis and increased serum TSLP concentrations were induced by topical application of the vitamin D3 analog MC903. Memory cells in peripheral blood were monitored weekly with flow cytometry. Memory recall was tested after intranasal ovalbumin challenge.

RESULTS

TSLP signaling in CD4(+) T cells is required for the generation/maintenance of memory cells after in vivo priming. TSLPR-deficient CD4(+) T cells have no defects in proliferation but do not survive 1 week after sensitization, and increased TSLP expression during sensitization significantly increased the frequency of memory cells. Although in vitro-differentiated TSLPR-deficient TH2 cells develop into memory cells with equal efficiency to wild-type cells, the recall response to airway antigen challenge is impaired. Moreover, after antigen challenge of mice with established TH2 memory, TSLP signaling in CD4(+) T cells significantly affects memory cell generation/maintenance from secondary effector cells.

CONCLUSION

TSLP signaling in CD4(+) T cells is required for not only TH2 memory cell formation in vivo but also the recall response of the memory cells to local antigen challenge.

Plasmodium berghei infection ameliorates atopic dermatitis-like skin lesions in NC/Nga mice

Background

Atopic diseases are more prevalent in industrialized countries than in developing countries. In addition, significant differences in the prevalence of allergic diseases are observed between rural and urban areas within the same country. This difference in prevalence has been attributed to what is called the ‘hygiene hypothesis’. Although parasitic infections are known to protect against allergic reactions, the mechanism is still unknown. The aim of this study was to investigate whether or not malarial infections can inhibit atopic dermatitis (AD)-like skin lesions in a mouse model of AD.

Methods

We used NC/Nga mice which are a model for AD. The NC/Nga mice were intraperitoneally infected with 1 × 10⁵Plasmoduim berghei (Pb) XAT-infected erythrocytes.

Results

Malarial infections ameliorated AD-like skin lesions in the NC/Nga mice. This improvement was blocked by the administration of anti-asialo GM1 antibodies, which are anti-natural killer (NK) cells. Additionally, adoptive transfer of NK cells markedly improved AD-like skin lesions in conventional NC/Nga mice; these suggest that the novel protective mechanism associated with malaria parasitic infections is at least, in part, dependent on NK cells.

Conclusions

We have experimentally demonstrated for the first time that malarial infections ameliorated AD-like skin lesions in a mouse model of AD. Our study could explain in part the mechanism of the ‘hygiene hypothesis’, which states that parasitic infections can inhibit the development of allergic diseases.

The expression of chemokine receptor CXCR3: relevance to disease activity of rheumatoid arthritis

Abstract  CXC chemokine receptor 3 (CXCR3) is selectively expressed on T helper 1 (Th1) type T cells and has been shown to be responsible for Th1-dominant immune responses. In this study, we analyzed the expression of CXCR3 on peripheral blood T lymphocytes of patients with rheumatoid arthritis (RA) by FACS analysis using antihuman CXCR3 monoclonal antibody and determined the clinical relevance in this disease. Significantly higher expression of CXCR3 was found on peripheral blood CD4+ T lymphocytes of RA patients than healthy controls. The CXCR3 expression in RA patients with a high erythrocyte sedimentation rate was significantly higher than in those with a low erythrocyte sedimentation rate. Moreover, we found that the CXCR3 expression in RA patients with long-term disease duration was significantly higher than in those with short-term disease. On the other hand, CC chemokine receptor 4 (CCR4), which was shown to be selectively expressed on Th2-type T cells, was expressed at low levels in RA patients as well as in healthy controls. The serum level of interleukin (IL)-18 in RA patients was higher than that in healthy controls, although there was no statistically significant difference. This study suggests that the Th1 immune response is predominant in RA and that CXCR3 may have relevance in regard to the disease course in RA patients.

Targeted reduction of CCR4⁺ cells is sufficient to suppress allergic airway inflammation

BACKGROUND

Bronchial asthma is characterized by allergic airway inflammation involving C-C chemokine receptor type 4 (CCR4)-positive Th2 cells. As such, we hypothesize that the disease can be alleviated by targeted-elimination of CCR4⁺ cells. Thymus and activation-regulated chemokine (TARC)-PE38, a TARC fused the exotoxin fragment PE38 from Pseudomonas aeruginosa, has been shown to efficiently kill CCR4⁺ cells by delivering the exotoxin fragment PE38 into CCR4⁺ cells. To test our hypothesis, we examined whether TARC-PE38 could suppress allergic airway inflammation in a mouse model of house dust mite (HDM)-induced allergic airway inflammation.

METHODS

We evaluated the effect of TARC-PE38 on the major characteristics of HDM-induced allergic airway inflammation. Airway hyperresponsiveness, lung histopathology, lung Th1/Th2 cell populations, and concentrations of Th1/Th2 cytokines in the lungs were assessed in HDM-sensitized and challenged mice in the presence and absence of TARC-PE38.

RESULTS

TARC-PE38 efficiently suppressed allergic airway inflammation by significantly reducing airway hyperresponsiveness, the overall area of inflammation, and goblet cell hyperplasia. In HDM-sensitized and challenged mice, TARC-PE38 specifically reduced the numbers of CCR4⁺ cells. This reduction was associated with a significant decrease in the production of Th2 cytokines in the airway,and a decrease in the number of leukocytes, including macrophages, eosinophils and lymphocytes, within the subepithelial area of the lungs and airway lumen. TARC-PE38 had noeffect on Th1 cells.

CONCLUSION

Our data suggest that the elimination of CCR4⁺ cells via TARC-PE38 treatment is sufficient to control allergic airway inflammation and airway hyperresponsiveness.

International Union of Basic and Clinical Pharmacology. [corrected]. LXXXIX. Update on the extended family of chemokine receptors and introducing a new nomenclature for atypical chemokine receptors

Sixteen years ago, the Nomenclature Committee of the International Union of Pharmacology approved a system for naming human seven-transmembrane (7TM) G protein-coupled chemokine receptors, the large family of leukocyte chemoattractant receptors that regulates immune system development and function, in large part by mediating leukocyte trafficking. This was announced in Pharmacological Reviews in a major overview of the first decade of research in this field [Murphy PM, Baggiolini M, Charo IF, Hébert CA, Horuk R, Matsushima K, Miller LH, Oppenheim JJ, and Power CA (2000) Pharmacol Rev 52:145-176]. Since then, several new receptors have been discovered, and major advances have been made for the others in many areas, including structural biology, signal transduction mechanisms, biology, and pharmacology. New and diverse roles have been identified in infection, immunity, inflammation, development, cancer, and other areas. The first two drugs acting at chemokine receptors have been approved by the U.S. Food and Drug Administration (FDA), maraviroc targeting CCR5 in human immunodeficiency virus (HIV)/AIDS, and plerixafor targeting CXCR4 for stem cell mobilization for transplantation in cancer, and other candidates are now undergoing pivotal clinical trials for diverse disease indications. In addition, a subfamily of atypical chemokine receptors has emerged that may signal through arrestins instead of G proteins to act as chemokine scavengers, and many microbial and invertebrate G protein-coupled chemokine receptors and soluble chemokine-binding proteins have been described. Here, we review this extended family of chemokine receptors and chemokine-binding proteins at the basic, translational, and clinical levels, including an update on drug development. We also introduce a new nomenclature for atypical chemokine receptors with the stem ACKR (atypical chemokine receptor) approved by the Nomenclature Committee of the International Union of Pharmacology and the Human Genome Nomenclature Committee.

Chemokine-like factor 1 (CLFK1) is over-expressed in patients with atopic dermatitis

Background: Human chemokine-like factor 1 (CKLF1), a recently discovered chemokine, has a broad spectrum of biological functions in immune-mediated diseases. It is highly expressed on Th2 lymphocytes and is a functional ligand for human CCR4. CKLF1 has a major role in the recruitment and activation of leucocytes, which plays an important role in the pathogenesis of allergic diseases. The present study was designed to determine the expression of CKLF1 in skin and serum in patients with atopic dermatitis (AD).

Methods: The CKLF1 protein expression in skin lesion was analyzed by immunohistochemistry and ELISA. The mRNA expression of CKLF1 in skin lesion was detected by Real-time PCR. The serum levels of CKLF1, IgE, eotaxin, IL-4, IL-5, and IL-13 were measured by ELISA.

Results: Histopathological changes in the skin of AD patients showed local inflammation with epidermal thickening and significant inflammatory cellular infiltration. Immunohistochemistry results demonstrated that CKLF1-staining positive cells were located in the epidermal and dermis, and that the CKLF1 expression in AD patients was significantly higher than that in normal control. The CKLF1 mRNA expression in AD patients was significantly higher than that in healthy controls. Serum CKLF1 and IgE levels were significantly increased in AD patients, as were the serum levels of IL-4, IL-5, IL-13 and eotaxin.

Conclusions: Both CKLF1 protien and mRNA levels are overexpressed in the skin lesion of AD patients, along with an increase in serum CKLF1 level, indicating that CKLF1 may play an important role in the development of atopic dermatitis.

The importance of CCR4 and CCR6 in experimental autoimmune encephalomyelitis

Chemokine receptors (CCRs) play important roles in the pathogenesis of immune-mediated diseases, as well as in normal immune response. We examined the role of CCR6 and CCR4 in experimental autoimmune encephalomyelitis (EAE) by using CCR6(-/-)CCR4(-/-) double knockout (DKO) and single knockout mice. DKO mice developed less severe EAE and presented repressed recall response in the induction phase, especially in the activity of T helper 17 (Th17) cells. CCR6 expression in central nervous system (CNS)-infiltrated cells was diminished in DKO. Our results suggest that CCR6 and CCR4 were involved in a more rapid progression of EAE and that their regulation might be a therapeutic target of human inflammatory demyelinating diseases.

Protease-activated receptor-2 induces proinflammatory cytokine and chemokine gene expression in canine keratinocytes

Although the molecular basis of the allergenicity remains to be fully elucidated, the ability of allergens to elicit allergic responses is at least partly attributed to their proteolytic activity. Protease-activated receptor-2 (PAR-2) is a G protein-coupled receptor that is activated by site-specific proteolysis by serine proteases and is known to mediate inflammatory processes in various tissues. In this study, we investigated the effects of trypsin, a major serine protease, and a human PAR-2 agonist peptide (SLIGKV-NH2) on proinflammatory cytokine and chemokine gene expression in the canine keratinocyte cell line CPEK. The expression of PAR-2 mRNA and protein in CPEK cells was detected by RT-PCR and Western blotting, respectively. The localization of PAR-2 in CPEK was examined by immunofluorescence. The mRNA expression levels of proinflammatory cytokines and chemokines were quantified by real-time RT-PCR. The free intracellular Ca(2+) concentration was measured using the Ca(2+)-sensitive fluorescent dye. CPEK cells constitutively expressed PAR-2 mRNA and protein. Stimulation of CPEK cells with trypsin induced significant upregulation of the mRNA expression levels of tumor necrosis factor alpha (TNF-α, P<0.05), granulocyte-macrophage colony-stimulating factor (GM-CSF, P<0.01), thymus and activation regulated chemokine (TARC/CCL17, P<0.01), and interleukin 8 (IL-8/CXCL8, P<0.01). Similarly, the PAR-2 agonist peptide increased the mRNA expression levels of TNF-α (P<0.05), GM-CSF (P<0.05), TARC/CCL17 (P<0.05), and IL-8/CXCL8 (P<0.05) in CPEK cells. Both trypsin and the PAR-2 agonist peptide increased the intracellular Ca(2+) concentration and PAR-2 internalization. These results suggest that PAR-2 activation can augment inflammatory cytokine and chemokine expression in canine keratinocytes, and it may initiate allergic inflammation through the proteolytic activity of allergens in canine atopic dermatitis.

Regulatory T cells migrate to airways via CCR4 and attenuate the severity of airway allergic inflammation

We have previously shown that regulatory T (Treg) cells that accumulate in the airways of allergic mice upregulate CC-chemokine receptor 4 (CCR4) expression. These Treg cells suppressed in vitro Th2 cell proliferation but not type 2 cytokine production. In the current study, using a well-established murine model of allergic lung disease or oral tolerance, we evaluated the in vivo activity of Treg cells in allergic airway inflammation with special focus on CCR4 function. We found that allergic, but not tolerant, mice treated with anti-CD25 Ab showed increased airway eosinophilia and IL-5- or IL-4-producing Th2 cells when compared with untreated mice. Notably, mice with CCR4 deficiency displayed an augmented airway allergic inflammation compared with wild-type or CCR2 knockout (KO) mice. The allergic phenotype of CCR4KO mice was similar to that observed in anti-CD25-treated mice. The exacerbated allergic inflammation of CCR4KO mice was directly associated with an impaired migration of Treg cells to airways and augmented frequency of pulmonary Th2 cells. Adoptive transfer of CD25(+)CD4(+) T cells expressing high levels of CCR4, but not CCR4KO CD25(+)CD4(+) T cells, attenuated the severe airway Th2 response of CCR4KO mice. Our results show that CCR4 is critically involved in the migration of Treg cells to allergic lungs that, in turn, attenuate airway Th2 activation and allergic eosinophilic inflammation.

CC chemokine receptors and chronic inflammation--therapeutic opportunities and pharmacological challenges

Chemokines are a family of low molecular weight proteins with an essential role in leukocyte trafficking during both homeostasis and inflammation. The CC class of chemokines consists of at least 28 members (CCL1-28) that signal through 10 known chemokine receptors (CCR1-10). CC chemokine receptors are expressed predominantly by T cells and monocyte-macrophages, cell types associated predominantly with chronic inflammation occurring over weeks or years. Chronic inflammatory diseases including rheumatoid arthritis, atherosclerosis, and metabolic syndrome are characterized by continued leukocyte infiltration into the inflammatory site, driven in large part by excessive chemokine production. Over years or decades, persistent inflammation may lead to loss of tissue architecture and function, causing severe disability or, in the case of atherosclerosis, fatal outcomes such as myocardial infarction or stroke. Despite the existence of several clinical strategies for targeting chronic inflammation, these diseases remain significant causes of morbidity and mortality globally, with a concomitant economic impact. Thus, the development of novel therapeutic agents for the treatment of chronic inflammatory disease continues to be a priority. In this review we introduce CC chemokine receptors as critical mediators of chronic inflammatory responses and explore their potential role as pharmacological targets. We discuss functions of individual CC chemokine receptors based on in vitro pharmacological data as well as transgenic animal studies. Focusing on three key forms of chronic inflammation--rheumatoid arthritis, atherosclerosis, and metabolic syndrome--we describe the pathologic function of CC chemokine receptors and their possible relevance as therapeutic targets.

Differing requirements for CCR4, E-selectin, and α4β1 for the migration of memory CD4 and activated T cells to dermal inflammation

CCR4 on T cells is suggested to mediate skin homing in mice. Our objective was to determine the interaction of CCR4, E-selectin ligand (ESL), and α(4)β(1) on memory and activated T cells in recruitment to dermal inflammation. mAbs to rat CCR4 were developed. CCR4 was on 5-21% of memory CD4 cells, and 20% were also ESL(+). Anti-TCR-activated CD4 and CD8 cells were 40-55% CCR4(+), and ∼75% of both CCR4(+) and CCR4(-) cells were ESL(+). CCR4(+) memory CD4 cells migrated 4- to 7-fold more to dermal inflammation induced by IFN-γ, TNF, TLR agonists, and delayed-type hypersensitivity than CCR4(-) cells. CCR4(+) activated CD4 cells migrated only 5-50% more than CCR4(-) cells to these sites. E-selectin blockade inhibited ∼60% of CCR4(+) activated CD4 cell migration but was less effective on memory cells where α(4)β(1) was more important. Anti-α(4)β(1) also inhibited CCR4(-) activated CD4 cells more than CCR4(+) cells. Anti-E-selectin reduced activated CD8 more than CD4 cell migration. These findings modify our understanding of CCR4, ESL, α(4)β(1), and dermal tropism. There is no strict relationship between CCR4 and ESL for skin homing of CD4 cells, because the activation state and inflammatory stimulus are critical determinants. Dermal homing memory CD4 cells express CCR4 and depend more on α(4)β(1) than ESL. Activated CD4 cells do not require CCR4, but CCR4(+) cells are more dependent on ESL than on α(4)β(1), and CCR4(-) cells preferentially use α(4)β(1). The differentiation from activated to memory CD4 cells increases the dependence on CCR4 for skin homing and decreases the requirement for ESL.

Administration of poly(I:C) improved dermatophagoides farinae-induced atopic dermatitis-like skin lesions in NC/Nga mice by the regulation of Th1/Th2 balance

Atopic dermatitis (AD) is characterized by a chronic and replapsing skin disease with Th2-dominant allergic inflammation. Poly(I:C) has been shown to have immunopotentiator properties, but its effect on AD has not been examined. In this study, the immunomodulatory effects of poly(I:C), using dermatophagoides farinae (Df)-induced AD-like skin lesions in NC/Nga mice, were investigated. The clinical scores were reduced significantly by the treatment with poly(I:C) at 25 and 50 μg/mouse. Histological analysis of the skin also revealed that treatment of poly(I:C) at 25 and 50 μg/mouse significantly reduced the inflammatory cellular infiltrate, including mast cells and eosinophils. Moreover, poly(I:C) increased the level of IFN-γ, a Th1 cytokine, whereas decreasing that of selective Th2 cytokine both in vivo and in vitro. The levels of serum IgE and Th2 chemokines such as eotaxin, TARC, in spleen cells were also reduced by poly(I:C). These results suggest that poly(I:C) inhibit the development of Df-induced AD-like skin lesions in NC/Nga mice through regulation of the Th1/Th2 balance. Therefore, our results indicate that poly(I:C) might be a useful immunomodulatory agent for the treatment of human AD.

Stratum corneum TARC level is a new indicator of lesional skin inflammation in atopic dermatitis

BACKGROUND

Management of atopic dermatitis (AD) requires judging the symptoms of local skin lesions and prescribing a suitable treatment. However, no method has been established in which objective measures can be used to evaluate the severity of local symptoms. We established a method for measuring thymus and activation-regulated chemokine (TARC) levels in the stratum corneum (scTARC), and examined whether the scTARC can be used as an indicator of the severity of local skin lesions in patients with AD.

METHODS

Stratum corneum was obtained from patients with AD by tape-stripping, and scTARC was evaluated using a TARC-specific antibody followed by image analysis. The scTARC was examined to determine correlation with the severity of local skin lesions (the severity of erythema, edema/papule, oozing/crusts, excoriations, lichenification, and xerosis) as well as with the severity scoring of atopic dermatitis (SCORAD) index, serum TARC level, serum IgE level, serum lactate dehydrogenase (LDH) level, interleukin (IL)-4-producing T cell ratio (Th2 cell ratio), and blood eosinophil count.

RESULTS

The scTARC was correlated with the severity of local skin lesions, especially with the erythema, edema/papule, and oozing/crusts score. The scTARC in the most severe lesions was also correlated with the SCORAD index, serum TARC level, serum IgE level, and blood eosinophil count. The scTARC was not, however, correlated with the serum LDH level and Th2 cell ratio.

CONCLUSION

An immunofluorescent technique combined with tape-stripping was used to measure scTARC. The scTARC can be used as an indicator of the severity of local acute inflammation in patients with AD.

Conversion of Th2 memory cells into Foxp3+ regulatory T cells suppressing Th2-mediated allergic asthma

Genetic and epigenetic programming of T helper (Th) cell subsets during their polarization from naive Th cells establishes long-lived memory Th cells that stably maintain their lineage signatures. However, whether memory Th cells can be redifferentiated into another Th lineage is unclear. In this study, we show that Ag-specific memory Th cells were redifferentiated into Foxp3(+) T cells by TGF-beta when stimulated in the presence of all-trans retinoic acid and rapamycin. The "converted" Foxp3(+) T cells that were derived from Th2 memory cells down-regulated GATA-3 and IRF4 and produced little IL-4, IL-5, and IL-13. Instead, the converted Foxp3(+) T cells suppressed the proliferation and cytokine production of Th2 memory cells. More importantly, the converted Foxp3(+) T cells efficiently accumulated in the airways and significantly suppressed Th2 memory cell-mediated airway hyperreactivity, eosinophilia, and allergen-specific IgE production. Our findings reveal the plasticity of Th2 memory cells and provide a strategy for adoptive immunotherapy for the treatment of allergic diseases.

TLR3 ligand polyinosinic:polycytidylic acid induces IL-17A and IL-21 synthesis in human Th cells

TLR3 and TLR9 recognize the pathogen-associated microbial patterns dsRNA and unmethylated DNA, respectively. The recent discovery that these receptors also recognize endogenous ligands from necrotic material has drawn increased attention to their involvement in autoimmunity. Th cell cytokines IL-17A and IL-21 have been assigned with pivotal roles in the regulation of such autoimmune diseases. IL-17A is the hallmark cytokine of the recently discovered proinflammatory Th cell subset T(H)17. By contrast, the expression of IL-21 does not seem to be limited to a single distinct Th cell subset. We investigated the expression of IL-17A and IL-21 in human CD4+ T cells in response to stimulation with the TLR3 ligand polyinosinic:polycytidylic acid (poly(I:C)) and the TLR9 ligand CpG. We discovered that poly(I:C) induced synthesis of both IL-17A and IL-21. Moreover, we found that poly(I:C) was able to drive the differentiation of naive Th cells into an IL-21 but not into an IL-17A-producing phenotype and did this without affecting the levels of transcription factors T-bet, GATA-3, or retinoic acid receptor-related orphan receptor C. Finally, we found that the IL-21-producing cells that were differentiated in response to poly(I:C) expressed the chemokine receptor CXCR3, which is important in the recruitment of T cells into inflamed joints in rheumatoid arthritis. This is the first report to show that the TLR3 ligand poly(I:C) can directly induce the synthesis of IL-17A and IL-21 and drive differentiation of human naive CD4+ T cells.

Blockade of CCR4 in a humanized model of asthma reveals a critical role for DC-derived CCL17 and CCL22 in attracting Th2 cells and inducing airway inflammation

BACKGROUND

As Th2 type lymphocytes orchestrate the cardinal features of allergic asthma, inhibiting their recruitment to the lungs could be of therapeutic benefit. Although human Th2 cells express the CCR4 chemokine receptor and increased production of CCR4 ligands has been found in asthmatic airways, studies in animals have reached contradictory conclusions on whether blocking this pathway would be beneficial.

OBJECTIVE

As a lack of efficacy might be due to differences between mouse and man, we readdressed this question using a humanized severe combined immunodeficiency model of asthma.

METHODS

Mice received peripheral blood mononuclear cells from house dust mite (HDM) allergic asthmatic patients and then underwent bronchial challenge with HDM.

RESULTS

This resulted in marked allergic inflammation and bronchial hyper-reactivity. Administration of CCR4 blocking antibody abolished the airway eosinophilia, goblet cell hyperplasia, IgE synthesis and bronchial hyper-reactivity. In this chimeric system, human CD11c+ dendritic cells (DCs) were the predominant source of CCR4 ligands, suggesting that DC-derived chemokines attract Th2 cells. In separate experiments using human DCs, in vitro exposure to HDM of DCs from HDM allergic patients but not healthy controls caused CCL17 and CCL22 release that resulted in chemoattraction of polarized human Th2 cells in a CCR4-dependent way.

CONCLUSIONS

Taken together, our data provide proof of concept that CCR4 blockade inhibits the salient features of asthma and justify further clinical development of CCR4 antagonists for this disease.

Cellular and molecular mechanisms in atopic dermatitis

Atopic dermatitis (AD) is a pruritic inflammatory skin disease associated with a personal or family history of allergy. The prevalence of AD is on the rise and estimated at approximately 17% in the USA. The fundamental lesion in AD is a defective skin barrier that results in dry itchy skin, and is aggravated by mechanical injury inflicted by scratching. This allows entry of antigens via the skin and creates a milieu that shapes the immune response to these antigens. This review discusses recent advances in our understanding of the abnormal skin barrier in AD, namely abnormalities in epidermal structural proteins, such as filaggrin, mutated in approximately 15% of patients with AD, epidermal lipids, and epidermal proteases and protease inhibitors. The review also dissects, based on information from mouse models of AD, the contributions of the innate and adaptive immune system to the pathogenesis of AD, including the effect of mechanical skin injury on the polarization of skin dendritic cells, mediated by keratinocyte-derived cytokines such as thymic stromal lymphopoietin (TSLP), IL-6, and IL-1, that results in a Th2-dominated immune response with a Th17 component in acute AD skin lesions and the progressive conversion to a Th1-dominated response in chronic AD skin lesions. Finally, we discuss the mechanisms of susceptibility of AD skin lesions to microbial infections and the role of microbial products in exacerbating skin inflammation in AD. Based on this information, we discuss current and future therapy of this common disease.

CCR4 and CCR10 ligands play additive roles in mouse contact hypersensitivity

Psoriasis, atopic dermatitis and allergic contact dermatitis are T-cell-mediated inflammatory skin diseases; chemokine receptors (CCR) 4 and 10 play an important role in the ligand-mediated recruitment of T cells into the skin in mice and humans, specifically with regards to tethering, firm adhesion and subsequent extravasation to the sight of injury. We utilized established murine models of dinitrofluorobenzene-, trimellitic acid anhydride- or oxazalone-induced contact hypersensitivity, to reflect the various Th-polarizations of different skin diseases, and investigated the functional effect of antibody blocking of single CCR ligands or combination therapy to block all CCR4 and CCR10 ligands. Our results indicate a greater reduction in inflammatory response--measured by oedema formation, myeloid cell and neutrophil infiltration and activity and CD3+ cell infiltration at the site of injury--with combination antibody therapy to CCR4 and CCR10 ligands versus controls, in nearly every tested condition. We conclude that blocking CCR4 and CCR10 simultaneously, or their ligands, should be beneficial in the treatment of T-cell-mediated skin diseases.

Interleukin-17 in inflammatory skin disorders

PURPOSE OF REVIEW

Recently, a novel and unique subset of interleukin (IL)-17-producing CD4+ T helper (Th17) cells, distinct from Th1 and Th2 cells, was discovered. The question is addressed as to what extent inflammatory skin diseases are associated with the actions of this newly discovered Th17 cell subset.

RECENT FINDINGS

Th17 cells are involved in protection against bacterial pathogens. In addition, it is now clear that Th17 cells may also be crucial in the pathogenesis of various chronic inflammatory diseases that were formerly categorized as Th1-mediated disorders.

SUMMARY

In this review, we summarize the current knowledge of IL-17 and Th17 cells and discuss the possible role of IL-17 in the pathology of psoriasis, contact hypersensitivity and atopic dermatitis. Whereas IL-17 may play an important role in the pathogenesis of psoriasis and contact hypersensitivity, its role in atopic dermatitis is still unclear.

Modulation of keratinocyte-derived MMP-9 by IL-13: a possible role for the pathogenesis of epidermal inflammation

Skin inflammation and remodeling are important pathophysiological features of chronic eczematous skin diseases. Matrix metalloproteinases (MMP) have been described to influence tissue remodeling and to facilitate cell migration through their ability to proteolyse the extracellular matrix. The aim of this study was to investigate the influence of IL-13 on the modulation of MMPs in human primary keratinocytes (KCs). IL-13 stimulation of KCs induced the expression of MMP-9 but not of MMP-3 or MMP-2 at mRNA level. A major substrate of MMP-9 is the type IV collagen of the basement membrane. IL-13 induced the release of active MMP-9 in KCs as detected by an ELISA-based assay. Moreover, migration of lymphocytes cultured with IL-13-activated KC showed increased migration through a basement membrane equivalent. The MMP-9 expression was prominent near the basement membrane of IL-13-treated skin biopsies. Collagen type IV staining pointed to a loss of this major basement membrane constituent in IL-13-treated skin. Finally, we demonstrated the concomitant mRNA expression of MMP-9 and IL-13 in biopsies from lesional, acutely inflamed eczematous skin. Our results suggest that release of active MMP-9 by IL-13-stimulated KCs may play a crucial role in skin inflammation by facilitating migration of leukocytes into the epidermis.

Suppression of Spontaneous Dermatitis in NC/Nga Murine Model by PG102 Isolated from Actinidia arguta

Atopic dermatitis (AD) is a chronic inflammatory skin disease, which requires safe and effective pharmacological therapy. We previously found that two preparations from Actinidia arguta, PG102T, and PG102E, could modulate Th1/Th2 pathways and suppress IgE biosynthesis. This study was performed to assess the therapeutic effects of PG102T and PG102E on the development of dermatitis in NC/Nga mice, characterized by the spontaneous onset of AD along with an elevated level of IgE under conventional conditions. PG102T or PG102E administration significantly reduced dermatitis severity as well as scratching tendency in conventional mice. The suppression of dermatitis by PG102 was accompanied by a decrease in the plasma level of IgE, IgG1, and IL-4 and also by an increase in that of IgG2a and IL-12. The splenic level of IL-4, IL-5, and IL-10 was downregulated, whereas that of IFN-gamma and IL-12 was increased. The number of eosinophils and the expression of eotaxin and thymus and activation-regulated chemokine were decreased by PG102T or PG102E. Histological findings also indicated that the thickening of epidermis/dermis and the dermal infiltration of inflammatory cells including mast cells were greatly inhibited. These data suggest that PG102 may be effective therapeutic agents for the treatment of AD.

CCL17 transgenic mice show an enhanced Th2-type response to both allergic and non-allergic stimuli

CC chemokine ligand (CCL)17 is implicated in the pathogenesis of atopic dermatitis (AD). To study the effect of CCL17 produced by keratinocytes (KC) during inflammation, we created transgenic (Tg) mice in which CCL17 is overexpressed in KC. Th2-type contact hypersensitivity (CHS) was enhanced and Th1-type CHS was suppressed in these mice. Increased numbers of CC chemokine receptor (CCR)4(+) cells and mast cells infiltrated in Tg mice. Levels of IL-4 mRNA were higher and those of IFN-gamma mRNA were lower in both acute and chronic CHS. Higher levels of serum IgE were observed after CHS. Numbers of CCR4(+) cells among PBMC were increased in Tg mice challenged acutely on the trunk. Chronic irritation with croton oil induced dermatitis and an elevation of serum IgE levels. Tg mice showed enhanced ear swelling after tape stripping. CCL17 was thought to modify the inflammation caused by sensitizing reagents as well as irritant reagents by attracting CCR4(+) cells into the lesional skin and creating a Th2-dominant condition. AD-like conditions such as increased number of mast cells and elevated levels of serum IgE were observed. Thus, CCL17 may participate in the pathogenesis of skin diseases such as AD by regulating both allergic and irritant inflammation.

IL-13-stimulated human keratinocytes preferentially attract CD4+CCR4+ T cells: possible role in atopic dermatitis

Skin inflammation in atopic dermatitis (AD) is characterized by the predominant infiltration of T-helper (Th)2-cells in lesional skin. However, the mechanism of recruitment of these cells in lesional skin of AD is not yet fully elucidated. In this study, we investigated the role of IL-13-stimulated human primary keratinocytes (HPKs) in the recruitment of lymphocytes and further delineated the mechanism of enrichment of these cells. In the migration assays, we observed preferential enrichment of CD4(+)CCR4(+) T cells towards IL-13-stimulated HPKs. Interestingly, CD4(+)CCR4(+) T cells from AD showed a higher chemotactic response than those from healthy individuals. We observed a significant increase in the expression of CCL22 in IL-13-stimulated HPKs as compared to unstimulated cells. Blocking of CCL22 in IL-13-stimulated HPKs by a neutralizing antibody resulted in 70-90% inhibition in migration of CD4(+)CCR4(+) T cells. Moreover, IL-13 upregulated IFN-gamma-induced chemokines, CCL2 and CCL5, in HPKs. Taken together, our data suggest that IL-13-stimulated HPKs participate in a positive feedback loop by preferentially enriching Th2-cells in lesional skin of acute AD patients. However, in chronic phase, IL-13 may act in synergy with IFN-gamma resulting in lymphocytes recruitment of a mixed phenotype at the site of inflammation, thus contributing to the chronification of eczema.

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.

Prominent involvement of activated Th1-subset of T-cells and increased expression of receptor for IFN-gamma on keratinocytes in atopic dermatitis acute skin lesions

BACKGROUND

Atopic dermatitis (AD) is an allergic skin disease mediated by antigen-specific IgE and an important role has been ascribed to CD4+ cells (Th cells). The objective of the study was to evaluate humoral and cellular immunological factors in the blood and the skin lesions of AD patients, and to analyze the presence of inflammatory cell-surface markers in blood and skin biopsies.

METHODS

The parameters for monitoring of 40 AD patients included results of prick test to inhalant allergens and epicutaneous (patch) test to contact allergens; values of total IgE, serum immunoglobulins (IgG, IgA, IgM) and different cell markers in the sera (CD3, CD4, CD8, CD20, CD21, CD23, HLA-DR). We also analyzed the presence of inflammatory cell-surface markers (CD3, CD4, CD8, CD20, CD20, CD1a, CD23, CD29, CD45Ro, IFNgamma+ markers) in the biopsies of skin lesions from 10 AD patients and 5 healthy controls (HCs) by immunohistochemical analysis (method of avidin-biotin immunoperoxidase).

RESULTS

Beside increased total serum IgE and positive skin tests, a significantly higher percentage of CD23+ cells with lower percentage of CD21+ cells was revealed in peripheral blood of AD patients in comparison to HCs. A positive epidermal expression of the majority of markers of T cells (CD3+, CD4+, CD8+, CD29+, CD45Ro+, IFNgamma+) and those of Langerhans' cells (LCs) (CD1a, CD23+), without those of B cells (CD20+) were noted in AD patients, but no in the skin of HCs. Furthermore, significant difference was also found between the two groups for increased expression of CD3, CD4, CD8, CD29, CD45Ro, IFNgamma+ markers (markers for IFNgamma receptor) and higher intraepidermal CD23+ LCs and intradermal CD1a+ LCs in AD skin lesions.

CONCLUSIONS

The obtained results suggest involvement of various humoral factors with increased production of IgE and cooperation between Th subsets and LCs, with higher production of related cytokines, and disturbed cellular immunity, including epidermal LCs with IgE receptors of high and low affinity in AD. The annotation of activated Th1 cells with increased producing of IFNgamma in acute AD skin lesions is notable, and might lead to IFNgamma binding to keratinocytes and consequently inflammatory skin changes in the disease.