TARC and RANTES, but not CTACK, are induced in two models of allergic contact dermatitis. Effects of cilomilast and diflorasone diacetate on T-cell-attracting chemokines

Mouse models of atopic dermatitis: a critical reappraisal

Mouse models for atopic dermatitis (AD) are an indispensable preclinical research tool for testing new candidate AD therapeutics and for interrogating AD pathobiology in vivo. In this Viewpoint, we delineate why, unfortunately, none of the currently available so-called "AD" mouse models satisfactorily reflect the clinical complexity of human AD, but imitate more "allergic" or "irriant" contact dermatitis conditions. This limits the predictive value of AD models for clinical outcomes of new tested candidate AD therapeutics and the instructiveness of mouse models for human AD pathophysiology research. Here, we propose to initiate a rational debate on the minimal criteria that a mouse model should meet in order to be considered relevant for human AD. We suggest that valid AD models should at least meet the following criteria: (a) an AD-like epidermal barrier defect with reduced filaggrin expression along with hyperproliferation, hyperplasia; (b) increased epidermal expression of thymic stromal lymphopoietin (TSLP), periostin and/or chemokines such as TARC (CCL17); (c) a characteristic dermal immune cell infiltrate with overexpression of some key cytokines such as IL-4, IL-13, IL-31 and IL-33; (d) distinctive "neurodermatitis" features (sensory skin hyperinnervation, defective beta-adrenergic signalling, neurogenic skin inflammation and triggering or aggravation of AD-like skin lesions by perceived stress); and (e) response of experimentally induced skin lesions to standard AD therapy. Finally, we delineate why humanized AD mouse models (human skin xenotransplants on SCID mice) offer a particularly promising preclinical research alternative to the currently available "AD" mouse models.

Tofacitinib Loaded Squalenyl Nanoparticles for Targeted Follicular Delivery in Inflammatory Skin Diseases

Tofacitinib (TFB), a Janus kinase inhibitor, has shown excellent success off-label in treating various dermatological diseases, especially alopecia areata (AA). However, TFB's safe and targeted delivery into hair follicles (HFs) is highly desirable due to its systemic adverse effects. Nanoparticles (NPs) can enhance targeted follicular drug delivery and minimize interfollicular permeation and thereby reduce systemic drug exposure. In this study, we report a facile method to assemble the stable and uniform 240 nm TFB loaded squalenyl derivative (SqD) nanoparticles (TFB SqD NPs) in aqueous solution, which allowed an excellent loading capacity (LC) of 20%. The SqD NPs showed an enhanced TFB delivery into HFs compared to the aqueous formulations of plain drug in an ex vivo pig ear model. Furthermore, the therapeutic efficacy of the TFB SqD NPs was studied in a mouse model of allergic dermatitis by ear swelling reduction and compared to TFB dissolved in a non-aqueous mixture of acetone and DMSO (7:1 v/v). Whereas such formulation would not be acceptable for use in the clinic, the TFB SqD NPs dispersed in water illustrated a better reduction in inflammatory effects than plain TFB's aqueous formulation, implying both encouraging good in vivo efficacy and safety. These findings support the potential of TFB SqD NPs for developing a long-term topical therapy of AA.

Cinnamomum camphora Leaves Alleviate Allergic Skin Inflammatory Responses In Vitro and In Vivo

In this study, we investigated the therapeutic potential of Cinnamomum camphora leaves on allergic skin inflammation such as atopic dermatitis. We evaluated the effects of C. camphora leaves on human adult low-calcium high-temperature keratinocytes and atopic dermatitis mice. C. camphora leaves inhibited Macrophage-derived chemokine (an inflammatory chemokine) production in interferon-γ (10 ng/mL) stimulated Human adult low-calcium high-temperature keratinocytes in a dose dependent manner. C. camphora leaves suppressed the phosphorylation of janus kinase signal transducer and activator of transcription 1. C. camphora leaves also suppressed the phosphorylation of extracellular signal-regulated kinase 1/2, a central signaling molecule in the inflammation process. These results suggest that C. camphora leaves exhibits anti-inflammatory effect via the phosphorylation of signal transducer and activator of transcription 1 and extracellular signal-regulated kinase 1/2. To study the advanced effects of C. camphora leaves on atopic dermatitis, we induced experimental atopic dermatitis in mice by applying 2,4-dinitrochlorobenzene. The group treated with C. camphora leaves (100 mg/kg) showed remarkable improvement of atopic dermatitis symptoms: reduced serum immunoglobulin E levels, smaller lymph nodes with reduced thickness and length, decreased ear edema, and reduced levels of inflammatory cell infiltration in the ears. Interestingly, the effects of C. camphora leaves on atopic dermatitis symptoms were stronger than those of hydrocort cream, a positive control. Taken together, C. camphora leaves showed alleviating effects on the inflammatory chemokine production in vitro and atopic dermatitis symptoms in vivo. These results suggest that C. camphora leaves help in the treatment of allergic inflammation such as atopic dermatitis.

Oleic acid as the active agent and lipid matrix in cilomilast-loaded nanocarriers to assist PDE4 inhibition of activated neutrophils for mitigating psoriasis-like lesions

Both phosphodiesterase (PDE4) inhibitors and omega-9 fatty acids show anti-inflammatory activity for treating inflamed skin diseases, but their efficacy remains low. Combinatorial agents are anticipated to offer an advanced strategy for efficient therapy. We prepared cilomilast-loaded oleic acid (OA) nanocarriers to test the inhibitory capability against human neutrophil stimulation and a murine psoriasis model. OA played dual roles in the nanocarriers as both the active ingredient and lipid matrix in the nanoparticulate core. OA nanoparticles but not free OA could restrain calcium mobilization in activated neutrophils. The inhibition level of superoxide anion and elastase by cilomilast-loaded OA nanocarriers approximated that of free forms. In the mouse model, the intradermal nanosystems reduced imiquimod-induced epidermal thickening from 230.4 to 63.1 μm. Transepidermal water loss was decreased from 30.2 to 11.3 g/m²/h by integrated nanocarriers. The nanosystems mitigated neutrophil infiltration and hyperproliferation in the psoriasiform lesion via decreased expression of cytokines and chemokines. STATEMENT OF SIGNIFICANCE: The long-term therapy for psoriasis is unsatisfactory due to the possible adverse effects and inefficiency after prolonged use. Both phosphodiesterase (PDE4) inhibitors and omega-9 fatty acids such as oleic acid (OA) show anti-inflammatory activity for treating inflamed skin diseases. Combinatorial agents are anticipated to offer an advanced strategy for efficient therapy. OA is also ideal for incorporation into nanoparticles to enhance particulate emulsification, drug entrapment, and biocompatibility. We prepared cilomilast-loaded oleic acid (OA) nanocarriers to test the inhibitory capability against human neutrophil stimulation and a murine psoriasis lesion. OA nanocarriers are indigenous to prevent neutrophil activation and the deterioration of psoriatic lesion. Cilomilast incorporation in OA nanocarriers could further mitigate the clinical score and suppressing proinflammatory mediators.

Direct activation of aryl hydrocarbon receptor by benzo[a]pyrene elicits T-helper 2-driven proinflammatory responses in a mouse model of allergic dermatitis

The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that binds to various environmental chemicals and contributes to numerous toxicological effects. However, the direct effects of AhR on the development of allergic diseases are not fully understood. The main aim of this study was to elucidate the action of AhR in the development of cutaneous allergies. Initially, the potential for a direct relationship between AhR and the immune cells was investigated in vitro, using murine bone marrow-derived dendritic cells, human epidermal keratinocytes, and the mixed leukocyte reaction assay. Benzo[a]pyrene (BaP) and 6-formylindolo[3,2-b]carbazole were used as selective ligands for the AhR. Pretreatment with BaP and/or 6-formylindolo[3,2-b]carbazole significantly induced cytokine release by activated keratinocytes and T-cell proliferation, whereas interleukin-12 production in bone marrow-derived dendritic cells was reduced by AhR activation. To confirm the in vitro results, in vivo experiments were also performed in T-helper (Th)2-type hapten toluene-2,4-diisocyanate- and Th1-type hapten dinitrochlorobenzene-induced mouse models of allergic dermatitis. Mice were orally administered BaP at 48, 24 and 4 hours before the final allergen challenge. In the Th2 model, ear-swelling response and scratching behavior were promoted by BaP exposure, which supported the observed significant increases in local cytokine secretion. The infiltration of helper T cells, B cells and dendritic cells into the auricular lymph node was significantly enhanced by BaP administration, although Th1-type immune responses were not influenced by AhR activation. Our findings demonstrate that AhR activation directly activates keratinocytes and T cells, which leads to the exacerbation of Th2-type cutaneous allergy.

Chemokine Signaling in Allergic Contact Dermatitis: Toward Targeted Therapies

Allergic contact dermatitis (ACD) is a common skin disease that results in significant cost and morbidity. Despite its high prevalence, therapeutic options are limited. Allergic contact dermatitis is regulated primarily by T cells within the adaptive immune system, but also by natural killer and innate lymphoid cells within the innate immune system. The chemokine receptor system, consisting of chemokine peptides and chemokine G protein-coupled receptors, is a critical regulator of inflammatory processes such as ACD. Specific chemokine signaling pathways are selectively up-regulated in ACD, most prominently CXCR3 and its endogenous chemokines CXCL9, CXCL10, and CXCL11. Recent research demonstrates that these 3 chemokines are not redundant and indeed activate distinct intracellular signaling profiles such as those activated by heterotrimeric G proteins and β-arrestin adapter proteins. Such differential signaling provides an attractive therapeutic target for novel therapies for ACD and other inflammatory diseases.

Topically applied manganese-porphyrins BMX-001 and BMX-010 display a significant anti-inflammatory response in a mouse model of allergic dermatitis

In this study, we topically administered two antioxidant compounds, the manganese-porphyrin-derivatives BMX-001 and BMX-010, in a mouse model of allergic dermatitis and compared the efficacy for reduction of itch and inflammation. In vitro effects of BMX-001 and BMX-010 on keratinocytes, bone marrow derived dendritic cells (BMDCs) and T-cells were initially analysed. For assessment of scratching behaviour, BMX-001 and BMX-010 (0.01 and 0.1 %) were topically applied 16 h and/or 1 h before compound 48/80 or toluene-2,4,-diisocyanate (TDI) challenge in a TDI induced mouse dermatitis model. Additionally, assessment of allergic skin inflammation was performed in a similar manner in the TDI model. Post-treatment ear thickness was measured 24 h after TDI challenge and compared to basal values. The mice were sacrificed and the ear auricle was removed for further analysis. In vitro, both BMX substances significantly inhibited cytokine production of keratinocytes as well as of BMDC and T-cell proliferation. Topical treatment with BMX cream resulted in a significant decrease in scratching behaviour in the compound 48/80 model, but not in the TDI model. Mice treated with BMX-001 and BMX-010 showed a moderate dose dependent decrease in ear thickness, and interestingly, the concentration of the cytokines IL-1β and IL-4 in inflamed skin was reduced by 80-90 % by all treatment options. These first results suggest the potential benefit of a BMX-001 and BMX-010 cream for the treatment of allergic-inflammatory skin diseases.

Allergic inflammation is augmented via histamine H4 receptor activation: The role of natural killer cells in vitro and in vivo

BACKGROUND

Natural Killer cells (NK cells) are identified as pivotal mediators in allergic skin diseases and accumulate in lesions of atopic dermatitis (AD) patients. Histamine levels are increased in these lesions and histamine is involved in chemotaxis in dendritic cells and NK cells.

OBJECTIVE

The aim of this study was to determine if the histamine H4 receptor (H4R) mediates NK cell chemotaxis and whether it influences interplay between NK cells and dendritic cells during the early phase of allergic inflammation.

METHODS

Chemotactic function of the H4R as well as the influence of the H4R on the cytokine profile of an NK cell-dendritic cell co-culture was studied in vitro. The effect of H4R activation on NK cell migration, NK cell-dendritic cell interaction and cytokine levels in the skin was further characterized in the murine TDI model of allergic dermatitis. Additionally, the impact of the H4R on dermal NK cells was determined in the ovalbumin (OVA)- induced allergic dermatitis model, comparing wild type and H4R knockout mice.

RESULTS

The selective H4R agonist ST-1006 induced NK cell chemotaxis in vitro, which was inhibited with the H4R antagonist JNJ7777120. In vivo, mice treated with TDI plus ST-1006 topically onto the ear, showed significantly enhanced ear swelling and an increased number of NK cells compared to just allergen challenged ears. CCL17 levels in the ear were also significantly increased 8h after allergen challenge. Histology revealed that the main source for increased CCL17 were dendritic cells. These effects could be blocked using the H4R antagonist JNJ7777120. In the chronic model of allergic dermatitis, OVA induced NK cell migration into lesional skin sites. The number of NK cells was lower in OVA-sensitized H4R knockout mice compared to wild type mice.

CONCLUSIONS

These results identify the H4R as a new target controlling NK cell migration and NK cell-dendritic cell interaction in the skin during early allergic inflammation. These results further suggest that blocking the H4R in the skin might be beneficial in diseases like AD.

Dieckol, a Component of Ecklonia cava, Suppresses the Production of MDC/CCL22 via Down-Regulating STAT1 Pathway in Interferon-γ Stimulated HaCaT Human Keratinocytes

Macrophage-derived chemokine, C-C motif chemokine 22 (MDC/CCL22), is one of the inflammatory chemokines that controls the movement of monocytes, monocyte-derived dendritic cells, and natural killer cells. Serum and skin MDC/CCL22 levels are elevated in atopic dermatitis, which suggests that the chemokines produced from keratinocytes are responsible for attracting inflammatory lymphocytes to the skin. A major signaling pathway in the interferon-γ (IFN-γ)-stimulated inflammation response involves the signal transducers and activators of transcription 1 (STAT1). In the present study, we investigated the anti-inflammatory effect of dieckol and its possible action mechanisms in the category of skin inflammation including atopic dermatitis. Dieckol inhibited MDC/CCL22 production induced by IFN-γ (10 ng/mL) in a dose dependent manner. Dieckol (5 and 10 μM) suppressed the phosphorylation and the nuclear translocation of STAT1. These results suggest that dieckol exhibits anti-inflammatory effect via the down-regulation of STAT1 activation.

Unique immunomodulatory effects of azelastine on dendritic cells in vitro

Allergic contact dermatitis and atopic dermatitis are among the most common inflammatory skin diseases in western countries, and antigen-presenting cells like dendritic cells (DC) are key players in their pathophysiology. Histamine, an important mediator of allergic reactions, influences DC maturation and cytokine secretion, which led us to investigate the immunomodulatory potential of the well-known histamine H1 receptor antagonists: azelastine, olopatadine, cetirizine, and pyrilamine. Unlike other H1 antihistamines, azelastine decreased lipopolysaccharide-induced tumor necrosis factor α and interleukin-12 secretion from murine bone marrow-derived DC. This effect was independent of histamine receptors H1, H2, or H4 and may be linked to inhibition of the nuclear factor kappa B pathway. Moreover, only azelastine reduced proliferation of allogenic T cells in a mixed leukocyte reaction. We then tested topical application of the H1 antihistamines on mice sensitized against toluene-2,4-diisocyanate, a model of Th2-mediated allergic contact dermatitis. In contrast to the in vitro results, all investigated substances were efficacious in reducing allergic ear swelling. Azelastine has unique effects on dendritic cells and T cell interaction in vitro. However, this did not translate into superior in vivo efficacy for Th2-mediated allergic dermatitis, possibly due to the effects of the antihistamines on other cell types involved in skin inflammation. Future research will have to clarify whether these properties are relevant to in vivo models of allergic inflammation with a different T cell polarization.

Participation of complement 3a receptor (C3aR) in the sensitization phase of Th2 mediated allergic contact dermatitis

The complement system has emerged as a bridge between innate and adaptive immune responses. An involvement of C3aR has been described during skin inflammation. The aim of the study was to investigate the role of C3a in a mouse model of allergic skin inflammation, such as allergic contact dermatitis (ACD) which is a clinical manifestation of contact sensitivity (CS). The sensitization phase was studied using the local lymph node test: Mice were sensitized on three consecutive days by application of non-irritant concentrations of toluene-2,4-diisocyanate (TDI; 0.5%) onto the ear skin. On day 5, auricular draining lymph nodes were obtained. The elicitation phase was investigated by sensitization with TDI on the depilated and tape-stripped abdominal skin and challenge with TDI on the ear skin and measuring of ear swelling in vivo and cytokine secretion in activated splenocytes in vitro respectively. Complement 3a receptor deficient (C3aRKO) mice showed increased cytokine responses (interleukin[IL]-5, IL-6, IL-17, granulocyte macrophage-colony stimulating factor [GM-CSF]) in the sensitization phase of ACD to TDI. However, no differences in CS responses to TDI were observed in C3aR KO mice compared with WT controls in the elicitation phase of ACD as assessed by measuring of ear swelling in vivo and cytokines in skin and in activated splenocytes in vitro, namely IL-1α, IL-2, IL-4, IL-5, IL-6, IL-10, IL-17, interferon-γ (IFN-γ), GM-CSF and tumor necrosis factor (TNF)-α. These findings provide a new insight into the participation of C3a in the sensitization phase of CS immune responses.

Dipeptidyl peptidase IV (DPP4) deficiency increases Th1-driven allergic contact dermatitis

BACKGROUND

CD26 or dipeptidyl peptidase IV (DPP4) is known to be involved in several immunological processes and has recently been reported to play a crucial role in the allergic responses of the lungs.

OBJECTIVES

To explore the impact of DPP4 on the allergic response of the skin.

METHODS

Skin biopsies from patients suffering from atopic dermatitis (AD) and healthy controls were investigated for the expression of CD26/DPP4. Furthermore, the functional impact of CD26 was investigated in two models of contact hypersensitivity using CD26/DPP4-deficient and wild-type rats. Dinitrochlorobenzene (DNCB) was used to induce a T helper type 1 (Th1)-dominated inflammation and toluene-2,3-diisocyanate for a Th2-pronounced inflammation. The inflammatory responses were determined by histological quantification, flow cytometry [fluorescence-activated cell sorting (FACS)], and an enzyme-linked immunosorbant assay (ELISA).

RESULTS

CD26/DPP4-expression was up-regulated in the lesional skin biopsies of patients compared with healthy controls as well as in both models of contact hypersensitivity. However, in the more Th2-driven model, a reduced inflammatory skin response was found in CD26/DPP4-deficient rats, analogous to the effects observed recently in a rat model of asthma. In partial contrast, there was an aggravation of local skin inflammation in CD26/DPP4-deficient rats under conditions of Th1-like skin inflammation.

CONCLUSION AND CLINICAL RELEVANCE

The up-regulation of CD26 in atopic dermatitis represents a new finding, which has also been seen in other inflammatory skin diseases. However, tissue expression of CD26/DPP4 in immunological skin response can either be beneficial or aggravating, depending on a possible Th1/Th2 shift. This might have consequences for humans suffering from diabetes mellitus treated by DPP4 inhibitors, who have eczematous skin diseases as a co-morbidity.

A protective role of complement component 3 in T cell-mediated skin inflammation

Keratinocytes synthesize complement component 3 (C3) constitutively, and increased expression of C3 has been described during skin inflammation. In this study, we investigated the role of C3 in T cell-mediated allergic contact dermatitis, which is a clinical manifestation of contact sensitivity (CS). C3-deficient mice (C3KO) showed substantial higher CS responses to haptens, inducing a Th1 cytokine-mediated skin inflammation (2,4-dinitrofluorobenzene and dinitrochlorobenzene), and to haptens known to induce a Th2-polarized inflammatory response (fluoro-isothiocynate and toluene-2,4-diisocyanate) as compared to their wild-type (WT) controls. There was a higher influx of GR-1(+) , CD4(+) , and CD8(+) cells into the skin of hapten-treated C3KO mice compared with WT mice. Activated splenocytes from C3KO mice immunized with DNCB secreted higher amounts of IFN-γ compared with WT controls but not of Th2 (IL-4, IL-5, and IL-10) cytokines or IL-17. A higher secretion of IL-12 from splenocytes of C3KO mice as compared with WT mice was observed after TLR-4 ligand (LPS) or TLR-2 ligand (peptidoglycan) stimulation. Thus, an increased expression of IL-12 and of IFN-γ may be responsible for the increased hapten-induced inflammation in C3 deficiency. Finally, we demonstrated that C3KO mice developed oral tolerance to haptens to a lower degree than WT mice. Our findings provide a new insight into a novel anti-inflammatory role of C3 in skin inflammation.

Role of the heparan sulfate proteoglycan syndecan-1 (CD138) in delayed-type hypersensitivity

The cell surface heparan sulfate proteoglycan syndecan-1 (CD138) modulates the activity of chemokines, cytokines, integrins, and other adhesion molecules which play important roles in the regulation of inflammation. We have previously shown that syndecan-1-deficient murine leukocytes display increased interactions with endothelial cells and increased diapedesis in vivo and in vitro. In this study, we demonstrate that syndecan-1 has an important function as a negative modulator in the murine contact allergy model of oxazolone-mediated delayed-type hypersensitivity (DTH). Following elicitation of the DTH response, syndecan-1-deficient mice showed an increase in leukocyte recruitment, resulting in an increased and prolonged edema formation. Expression of the cytokines TNF-alpha and IL-6 of the chemokines CCL5/RANTES and CCL-3/MIP-1alpha and of the adhesion molecule ICAM-1 were significantly increased in syndecan-1-deficient compared with wild-type mice. In wild-type mice, syndecan-1 mRNA and protein expression was reduced during the DTH response. The differentially increased adhesion of syndecan-1-deficient leukocytes to ICAM-1 was efficiently inhibited in vitro by CD18-blocking Abs, which emerges as one mechanistic explanation for the anti-inflammatory effects of syndecan-1. Collectively, our results show an important role of syndecan-1 in the contact DTH reaction, identifying syndecan-1 as a novel target in anti-inflammatory therapy.

Topical application of sphingosine-1-phosphate and FTY720 attenuate allergic contact dermatitis reaction through inhibition of dendritic cell migration

Migration of Langerhans cells (LCs) from the skin to the lymph node is an essential step in the pathogenesis of allergic contact dermatitis (ACD). Therefore, inhibition of LC-migration could be a promising strategy to improve this skin disease. Effects of sphingosine-1-phosphate (S1P) and the immunomodulator FTY720 on LC trafficking is not well defined, yet. Thus, we investigated the action of topically administered S1P and FTY720 in a murine model of ACD. Most interestingly, FTY720 as well as S1P inhibited the inflammatory reaction in the elicitation phase of ACD. In the sensitization phase, FTY720, and S1P reduced the weight and cell count of the draining auricular lymph node, as well as immigrated dendritic cells provoked by repetitive topical administration of the hapten. Correspondingly, the density of LCs in the epidermis was higher in FTY720- and S1P-treated mice compared to vehicle treatment. A skin dendritic cell migration assay confirmed the significant inhibition of dendritic cell migration by FTY720 and S1P. These data supply conclusive evidence that the strategy of targeting the migratory response of LCs with locally acting S1P or FTY720 represents an emerging option in the treatment of allergic skin diseases like contact hypersensitivity and atopic dermatitis.

Microarray-Based In Vitro Test System for the Discrimination of Contact Allergens and Irritants: Identification of Potential Marker Genes

Background: Animal tests have been used to characterize the potential of chemicals to produce allergic contact dermatitis, but this approach is increasingly a matter of public and political concern. Our aim was to develop and validate an alternative in vitro test that can identify contact allergens.

Methods: We developed a targeted microarray containing oligonucleotide probes for 66 immune-relevant genes and analyzed gene expression in monocyte-derived dendritic cells (Mo-DCs) treated with 1 irritant (SDS) and 2 prominent contact allergens, nickel and Bandrowski’s base (BB), which is the oxidation product of the most important hair dye allergen, p-phenylenediamine.

Results: Comparing RNA amounts in chemical-treated and solvent-treated cells, we identified significant changes in the expression of 21 genes and 10 genes after exposure of immature DCs (iDCs) to nickel and BB, respectively, but not after exposure to SDS. Eight genes were differentially expressed after application of both nickel and BB. Real-time PCR was used to confirm the results for selected genes.

Conclusion: We propose a microarray-based in vitro test that might allow the identification of contact allergens. Independently from donor variability, several immune-relevant genes were up- or downregulated after the application of the tested sensitizers to iDCs, therefore presenting potential marker genes. While reducing the number of laboratory animals used, this test would also enable reliable analysis of chemicals using a human system.

Maternal allergic contact dermatitis causes increased asthma risk in offspring

Background

Offspring of asthmatic mothers have increased risk of developing asthma, based on human epidemiologic data and experimental animal models. The objective of this study was to determine whether maternal allergy at non-pulmonary sites can increase asthma risk in offspring.

Methods

BALB/c female mice received 2 topical applications of vehicle, dinitrochlorobenzene, or toluene diisocyanate before mating with untreated males. Dinitrochlorobenzene is a skin-sensitizer only and known to induce a Th1 response, while toluene diisocyanate is both a skin and respiratory sensitizer that causes a Th2 response. Both cause allergic contact dermatitis. Offspring underwent an intentionally suboptimal protocol of allergen sensitization and aerosol challenge, followed by evaluation of airway hyperresponsiveness, allergic airway inflammation, and cytokine production. Mothers were tested for allergic airway disease, evidence of dermatitis, cellularity of the draining lymph nodes, and systemic cytokine levels. The role of interleukin-4 was also explored using interleukin-4 deficient mice.

Results

Offspring of toluene diisocyanate but not dinitrochlorobenzene-treated mothers developed an asthmatic phenotype following allergen sensitization and challenge, seen as increased Penh values, airway inflammation, bronchoalveolar lavage total cell counts and eosinophilia, and Th2 cytokine imbalance in the lung. Toluene diisocyanate treated interleukin-4 deficient mothers were able to transfer asthma risk to offspring. Mothers in both experimental groups developed allergic contact dermatitis, but not allergic airway disease.

Conclusion

Maternal non-respiratory allergy (Th2-skewed dermatitis caused by toluene diisocyanate) can result in the maternal transmission of asthma risk in mice.

Effects of cyclosporin A and cilomilast on activated canine, murine and human keratinocytes

The calcineurin inhibitor cyclosporin A and the phosphodiesterase 4 inhibitor cilomilast exhibit potent immunomodulatory properties which make them interesting therapeutics for the treatment of skin disorders like canine and human atopic dermatitis. Cyclosporin A and phosphodiesterase 4 inhibitors have already demonstrated clinical efficacy in the therapy of canine and human atopic dermatitis. Their direct impact on keratinocytes, especially canine keratinocytes, is less obvious. Thus, an investigation was carried out to ascertain whether cyclosporin A and cilomilast modulate keratinocyte proliferation and secretion of proinflammatory mediators. Cyclosporin A inhibited canine and murine keratinocyte proliferation, whereas cilomilast had no affect. Cyclosporin A and cilomilast reduced the lipopolysaccharide-induced prostaglandin E2 synthesis in canine and murine keratinocytes. Both immunomodulators also inhibited the production of the CXC chemokine KC and CCL2 in the murine keratinocyte cell line MSC-P5. The two immunomodulators also significantly reduced the interferon-gamma-induced production of interferon-gamma-inducible protein 10 in human keratinocytes (HaCaT cells). Thus, cyclosporin A and cilomilast directly modulate keratinocyte functions which might contribute to the anti-inflammatory and immunomodulatory action of these compounds in the treatment of allergic skin diseases.

Presence of circulating CCR10+ T cells and elevated serum CTACK/CCL27 in the early stage of mycosis fungoides

PURPOSE

Mycosis fungoides (MF), a common type of cutaneous T cell lymphoma with an indolent clinical course, has the characteristic that malignant T cell clones are recruited into the skin from the early disease stages. The mechanisms of recruitment have been suggested from our knowledge of various chemokine-chemokine receptor interactions. Recently, CCR10 and CTACK/CCL27 were proposed to play a role in the recruitment of other types of cutaneous T cell lymphoma. We examined the expression of CCR10 in peripheral blood and serum CTACK/CCL27 levels in patients with MF.

EXPERIMENTAL DESIGN

Eighteen patients with MF, six patients with atopic dermatitis, and nine healthy volunteers were enrolled in our investigation. We investigated the differences in CCR10+ CD4+ expression in peripheral blood mononuclear cells by flow cytometry. Serum CTACK/CCL27 levels were determined using a CTACK/CCL27 ELISA assay kit.

RESULTS

The number of circulating CCR10+ CD4+ cells was significantly higher in MF peripheral blood than in controls, even during the early stages. In lesional MF skin, infiltrating tumor cells also showed extensive expression of CCR10. The serum level of CTACK/CCL27 was higher in patients with MF than normal controls, but no statistical difference was found compared with atopic dermatitis patients.

CONCLUSIONS

CCR10-CTACK/CCL27 interactions between circulating T cells and keratinocytes would seem to play an important role in the pathophysiology of MF from the early disease stages.

Non-steroidal and steroidal anti-inflammatory drugs vary in their modulation of dendritic cell function in the elicitation phase of allergic contact dermatitis

The role of dendritic cells (DCs) in allergic contact dermatitis has been clearly demonstrated for the induction phase. However, the situation during the elicitation phase is very complex within a distinct inflammatory response. This study was performed to exploit DC migration in the elicitation phase in a mouse model of allergic contact dermatitis and to evaluate the effects of steroidal and non-steroidal anti-inflammatory drugs (NSAIDs) on DC migration through skin in the elicitation phase of allergic contact dermatitis. Topically and systemically administered acetylsalicylic acid (ASA) did not reduce the inflammatory response. However, systemically administered ASA significantly reduced the DC migration to the draining lymph node. In contrast, topically administered indomethacin reduced the inflammatory response, but had only minor effects on DC migration, whereas diflorasone diacetate reduced both inflammatory reaction and DC migration. Thus, NSAIDs may differ in their inhibitory action in immunological inflammation.

Cilomilast, tacrolimus and rapamycin modulate dendritic cell function in the elicitation phase of allergic contact dermatitis

BACKGROUND

Cilomilast and tacrolimus as well as rapamycin are potential drugs for the treatment of allergic skin diseases like atopic dermatitis and allergic contact dermatitis.

OBJECTIVES

To compare the in vitro and in vivo immunomodulatory effects of the phosphodiesterase 4 inhibitor cilomilast with those of tacrolimus and rapamycin.

METHODS

The in vitro action of cilomilast, tacrolimus and rapamycin were tested in a mixed leucocyte reaction (MLR). In vivo, the inhibitory action of the immunomodulatory drugs was compared in the toluene-2,4-diisocyanate (TDI)-induced allergic inflammatory response with particular focus on dendritic cell (DC) function.

RESULTS

Cilomilast, tacrolimus and rapamycin were all able to inhibit DC-mediated T-cell activation in a MLR. But it was demonstrated for cilomilast that the target cells are T cells rather than DC. In vivo, a combination of systemic and topical administration of each of these three substances significantly inhibited swelling in the murine ear 16 h after TDI challenge. There was also a reduction in the weight of the draining auricular lymph node, in lymphocyte cell count, and in the number of emigrated DC. The density of Langerhans cells in the epidermis was correspondingly higher in mice treated with cilomilast, tacrolimus and rapamycin than in those treated with vehicle. All three substances were found to inhibit DC migration ex vivo in a skin DC migration assay performed on ear tissue after TDI challenge.

CONCLUSIONS

DC migration into the draining lymph node also takes place in the elicitation phase of allergic contact dermatitis and this migration can be influenced by tacrolimus and rapamycin, and, to a lesser extent, by cilomilast.