Epidermal cytokines IL-1beta, TNF-alpha, and IL-12 in patients with atopic dermatitis: response to application of house dust mite antigens

IL-1β and Allergy: Focusing on Its Role in Allergic Rhinitis

Allergic rhinitis (AR) is a chronic upper airway immune-inflammation response mediated by immunoglobulin E (IgE) to allergens and can seriously affect the quality of life and work efficiency. Previous studies have shown that interleukin-1β (IL-1β) acts as a key cytokine to participate in and promote the occurrence and development of allergic diseases. It has been proposed that IL-1β may be a potential biomarker of AR. However, its definitive role and potential mechanism in AR have not been fully elucidated, and the clinical sample collection and detection methods were inconsistent among different studies, which have limited the use of IL-1β as a clinical diagnosis and treatment marker for AR. This article systematically summarizes the research advances in the roles of IL-1β in allergic diseases, focusing on the changes of IL-1β in AR and the possible interventions. In addition, based on the findings by our team, we provided new insights into the use of IL-1β in AR diagnosis and treatment, in an attempt to further promote the clinical application of IL-1β in AR and other allergic diseases.

Anti-allergic effect of ascorbic acid derivative DDH-1 in a mouse model of atopic dermatitis

Atopic dermatitis (AD) is the most common inflammatory skin disease, which is characterized by excessive Th2 immune responses. In AD patients, the expression of the chemokines CCL17 and CCL22 is increased in skin lesions, leading to the infiltration of Th2 cells. In addition, typical pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6, have also been shown to be associated with the pathogenesis of AD. Recently, DDH-1, an ascorbic acid derivative, has been synthesized and demonstrated to have a more stabilized structure and better skin penetrability. Furthermore, DDH-1 has been shown to suppress pro-inflammatory cytokine expression in vitro and in vivo. Therefore, using an AD mouse model, we evaluated the effect of DDH-1 to reduce allergic skin inflammation. We found that cutaneous administration of DDH-1 significantly reduced the expression levels of TNF-α, IL-1β, and IL-6 in the skin lesions of AD-like mice. Additionally, DDH-1 administration also significantly reduced the expression levels of CCL17 and CCL22, resulting in decreased skin infiltration of Th2 cells. Consequently, DDH-1 reduced ear and epidermal thickness, the serum IgE levels, and the number of infiltrating inflammatory cells and mast cells into the AD-like skin lesions. Combination treatment with DDH-1 and corticosteroid more efficiently improved the skin lesions compared to corticosteroid alone. Collectively, our results suggest that DDH-1 has an anti-allergic effect in an AD mouse model by reducing not only the pro-inflammatory cytokine expression but also the Th2-associated chemokine expression. Thus, DDH-1 may be beneficial for AD treatment and prevention as a monotherapy or in combination with corticosteroids.

Comprehensive Phytochemical Profiling of Polyherbal Divya-Kayakalp-Vati and Divya-Kayakalp-Oil and Their Combined Efficacy in Mouse Model of Atopic Dermatitis-Like Inflammation Through Regulation of Cytokines

Purpose

Atopic dermatitis (AD) is a chronic inflammatory disease that varies in signs and symptoms in different individuals. General symptoms include dryness of the skin, itching, and development of red to brownish-gray patches. Divya-Kayakalp-Vati (DKV) and -Oil (DKO) are Indian polyherbal compositions prescribed for treating inflammatory skin diseases. In the present study, we evaluated the anti-inflammatory efficacy of DKV and DKO co-treatment (DKV-O) in ameliorating Oxazolone (OXA)-stimulated AD-like inflammation and pro-inflammatory cytokine release in a Swiss albino mouse model.

Methods

Phytochemical profiling of the DKV and DKO were done using Liquid Chromatography-Mass Spectroscopy (LC-MS) QToF. Swiss albino mice were sensitized for 7 days and treated with OXA in their ear region. Stimulated and control animals were orally treated with DKV and topically with DKO. Anti-inflammatory efficacy of DKV-O was determined in OXA-treated animals through physiological, histopathological, and biochemical parameter analysis.

Results

DKV and DKO formulations individually contained 39 and 59 phytochemicals, respectively. Many of the phytochemicals have been reported to have anti-inflammatory activities. In the OXA-sensitized Swiss albino mice, combined treatment with DKV-O, and separately with Dexamethasone (positive control) significantly reduced the OXA-stimulated ear edema, biopsy weight, and epidermal thickness. DKV-O further reduced OXA-stimulated induction of inflammatory lesions, neutrophil influx, and release of Interleukin (IL)-1β, IL-6, tumor necrosis factor-α, and myeloperoxidase.

Conclusion

Finally, DKV-O co-treatment showed good pharmacological effects in ameliorating AD-like inflammation through the modulation of inflammatory cell influx and release of soluble mediators. Therefore, DKV-O treatment can be used as a suitable polyherbal therapeutic against AD-like inflammatory diseases.

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The role of interleukin-1β in the immune response to contact allergens

Interleukin-1β (IL-1β) is an important pro-inflammatory cytokine that has an effect on almost every cell lineage in the body. By blocking IL-1β and investigating the IL-1β signaling pathway, several studies have demonstrated a central role of IL-1β in the response to contact allergens. This review summarizes the current literature regarding the basic immunological mechanisms mediated by IL-1β in the different phases of allergic contact dermatitis (ACD) and highlights potential IL-1β-targeted treatment options, which in the future may be relevant in the treatment of patients with ACD. This review is based primarily on studies using various mouse models and human in vitro studies, since clinical studies on the effect of IL-1β in ACD are lacking.

Skin tape sampling technique identifies proinflammatory cytokines in atopic dermatitis skin

BACKGROUND

Monitoring the effects of biologic therapies in skin diseases will benefit from alternative noninvasive skin sampling techniques to evaluate immune pathways in diseased tissue early and longitudinally.

OBJECTIVE

To establish a minimally invasive profiling of skin cytokines for diagnosis, therapeutic response monitoring, and clinical research in atopic dermatitis (AD) and other skin diseases, particularly in pediatric cohorts.

METHODS

We developed a novel method for cytokine profiling in the epidermis using skin tape strips (STSs) in a setting designed to maximize the efficiency of protein extraction from STSs. This method was applied to analyze STS protein extracts from the lesional skin of children having AD (n = 41) and normal, healthy controls (n = 22). A total of 20 cytokines were probed with the ultrasensitive Mesoscale multiplex cytokine assay.

RESULTS

A significant increase in interleukin (IL)-1b (P < .01), IL-18 (P < .001), and IL-8 (P < .001) with a decrease in IL-1a (P < .001) in the stratum corneum of AD lesional skin was found. Concurrently, an increase in markers associated with type 2 inflammatory response was readily detectable in AD lesional skin, including C-C motif chemokine ligand (CCL) 22, CCL 17, and thymic stromal lymphopoietin (TSLP). The levels of IL-1b, IL-18, and TSLP exhibited positive correlations with the AD severity index (Scoring AD index) and skin transepidermal water loss (TEWL), whereas an inverse correlation between IL-1a and Scoring AD index and IL-1a and TEWL was found. The levels of CCL17, CCL22, TSLP, IL-22, and IL-17a correlated with skin TEWL measurements.

CONCLUSION

Using minimally invasive STS analysis, we identified cytokine profiles easily sampled in AD lesional skin. The expression of these markers correlated with disease severity and reflected changes in TEWL in lesional skin. These markers suggest new response assessment targets for AD skin.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03168113.

Alnus Sibirica Extracts Suppress the Expression of Inflammatory Cytokines Induced by Lipopolysaccharides, Tumor Necrosis Factor-α, and Interferon-γ in Human Dermal Fibroblasts

The effects of Alnus sibirica (AS) extracts on cytokine expression induced by inflammatory stimulants were examined in human dermal fibroblasts (HDFs) and RAW264.7 cells. The anti-oxidative effect and effect on cell viability of AS extracts were evaluated, and four extracts with the highest anti-oxidative effects were selected. HDFs and RAW264.7 cells were treated with inflammatory stimulants, and the expression of cytokines involved in acute (IL-6 and IL-10) and chronic (IL-18) inflammation, the initiation of the immune response (IL-33), and non-specific immune responses (IL-1β, IL-8, and TNF-α) were determined using a reverse-transcription polymerase chain reaction. LPS increased the expression of all the cytokines, except for IL-18; however, AS extracts, particularly AS2 and AS4, reduced this increase, and TNF-α treatment markedly increased the expression of cytokines related to non-specific immune responses. IFN-γ treatment induced no significant changes, except for increased IL-33 expression in HDFs. AS extracts inhibited the increase in the expression of IL-33 and other cytokines in HDFs. Thus, the exposure of HDFs and RAW264.7 cells to inflammatory stimulants increased the expression of cytokines related to all the inflammatory processes. HDFs are involved not only in simple tissue regeneration but also in inflammatory reactions in the skin. AS2 and AS4 may offer effective therapy for related conditions.

Endotyping of non-allergic, allergic and mixed rhinitis patients using a broad panel of biomarkers in nasal secretions

Background

Endotyping chronic rhinitis has proven hardest for the subgroup of non-allergic rhinitis (NAR) patients. While IgE-related inflammation is typical for allergic rhinitis (AR), no markers have been found that can be seen to positively identify NAR. A further complication is that AR and NAR might co-exist in patients with mixed rhinitis. As previous studies have considered only a limited number of inflammatory mediators, we wanted to explore whether a wider panel of mediators could help us refine the endotyping in chronic rhinitis patients.

Objective

To endotype chronic rhinitis, and non-allergic rhinitis in particular, with help of molecular or cellular markers.

Method

In this study we included 23 NAR patients without allergen sensitizations and with persistent rhinitis symptoms, 22 pollen sensitized rhinitis patients with seasonal symptoms, 21 mixed rhinitis patients with pollen-related symptoms and persistent symptoms outside of the pollen season, and 23 healthy controls without any symptoms. Nasal secretions were collected outside of pollen season and differences between the endotypes were assessed for a broad range of inflammatory mediators and growths factors using a multiplex ELISA.

Results

Although we were able to identify two new nasal secretion makers (IL-12 and HGF) that were low in mixed and AR patients versus NAR and healthy controls, the most intriguing outcome is that despite investigating 29 general inflammatory mediators and growth factors no clear profile of non-allergic or mixed rhinitis could be found.

Conclusion

Classical inflammatory markers are not able to differentiate between non-allergic or mixed rhinitis patients and healthy controls.

Cytokine Gene Polymorphisms in Saudi Patients With Atopic Dermatitis: A Case-Control Study

The cause of atopic dermatitis (AD) is multifactorial and a number of genes including cytokines have been involved. We genotyped 315 subjects for polymorphisms in TNF-α and TNF-β and IL-10 genes. Patients had significantly higher frequency of GA genotype of TNF-α (−308 G/A) than healthy controls. Patients with AD and controls had similar distribution of A and G alleles. Genotype AA was found in 7.11% of controls while completely absent in cases. The frequencies of genotypes GG and AA of TNF-β (+252 A/G) polymorphism were higher whereas the frequency of genotype GA was significantly lower in patients than the controls. The frequencies of genotypes GG and AA of IL-10 (1082 G/A) polymorphism were significantly increased whereas genotype GA was decreased in patients than the controls. It is concluded that TNF-α (−308 G/A), TNF-β (+252 A/G), and IL-10 (−1082 G/A) polymorphisms are linked with the susceptibility of AD in Saudis and can be a risk factor.

Cryptotanshinone inhibits IgE‑mediated degranulation through inhibition of spleen tyrosine kinase and tyrosine‑protein kinase phosphorylation in mast cells

Atopic dermatitis (AD) is a type of chronic skin inflammation and one of the most common relapsing allergic diseases, which presents with a severe rash and itchy skin lesions. The pathogenesis of AD is primarily associated with hyper‑activated mast cells, which makes them an effective treatment target. After cross‑linking the antigen/immunoglobulin (Ig) E complex binds to its high affinity receptor FcεRl on the surface of mast cells. The cells subsequently secrete excessive pro‑inflammatory mediators, including histamine and cytokines, which lead to pruritus and immune cell infiltration in the skin lesions. The present study screened natural compounds that have an inhibitory effect on IgE/antigen‑mediated secretory activity. It was revealed that cryptotanshinone (CRT), a natural compound extracted from Salvia miltiorrhiza Bunge, had inhibitory effects on the IgE/antigen complex. The underlying mechanism by which CRT exerted an anti‑allergy/inflammatory function was investigated using rat basophilic leukaemia (RBL) cells for degranulation assays and a 1‑chloro‑2,4‑dinitrobenzene (DNCB)‑induced AD Balb/c mouse model for in vivo study. CRT effectively mitigated the secretion of pro‑inflammatory cytokines, including tumor necrosis factor‑α and interleukin 1β, as well as immune cell infiltration into skin lesions in a mouse model of AD‑like skin disease induced by dinitrochlorobenzene. The inhibitory effect of CRT on IgE‑mediated mast cell degranulation was mediated by the inhibition of tyrosine kinase‑dependent degranulation signalling pathways involving spleen tyrosine kinase and Lyn. The present study revealed CRT as an inhibitor of mast cell degranulation. Therefore, CRT may be considered for development as a therapeutic drug to treat IgE‑mediated skin diseases.

The Anti-Inflammatory Effect of Fructus Kochiae on Allergic Contact Dermatitis Rats via pERK1/2/TLR4/NF-κB Pathway Activation

Allergic contact dermatitis (ACD) is a common irritability skin disease, which can be cured by using the Chinese patent medicine. To explore the pharmacological effect of total flavonoids of Fructus Kochiae (FK) on ACD, we used dinitrochlorobenzene- (DNCB-) induced ACD rats. Five groups were used in our experiments. The normal group and the DNCB group were treated with 0.5% CMC-Na; the DNCB + hFK group was treated with a high dose of total flavonoids of FK (200 mg/kg); the DNCB + lFK group was treated with a low dose of FK (100 mg/kg); the DNCB + Pre group was treated with prednisolone acetate (2.5 mg/kg). The results showed that FK treatment had significantly attenuated the inflammation induced by DNCB. The increased concentration of cytokines including IL-6, IL-18, and IFN-γ in ACD rats could be reversed by the FK administration, while IL-10 expressed the opposite result; the expression level of TLR4, pERK_1/2, and NF-κB could be downregulated by the treatment with FK in the ACD rat. In a word, the total flavonoids of the FK had an anti-inflammatory effect on the DNCB-induced ACD rat; this regulatory mechanism was highly possible based on the pERK_1/2/TLR4-NF-κB pathway activation.

Immunologic, microbial, and epithelial interactions in atopic dermatitis

OBJECTIVE

To provide an overview of studies contributing to the understanding of immunologic, microbial, and epithelial interactions in atopic dermatitis.

DATA SOURCES

PubMed literature review (2000-2017) and meeting abstracts from recent international dermatology conferences.

STUDY SELECTIONS

Articles discussing primarily human disease.

RESULTS

Clinical studies showed that atopic dermatitis is a type 2 immune-centered disease with a systemic inflammatory component but with heterogeneous treatment responses. This suggests that other factors are likely involved in shaping the skin disease phenotype, including microbial dysbiosis and epidermal barrier dysfunction.

CONCLUSION

Recent clinical investigation has significantly expanded our knowledge on disease pathogenesis in atopic dermatitis, and current and future clinical trials will most likely further help to elucidate this complex, heterogeneous skin disease.

Effects of Emollient Containing Bee Venom on Atopic Dermatitis: A Double-Blinded, Randomized, Base-Controlled, Multicenter Study of 136 Patients

BACKGROUND

Atopic dermatitis (AD) is a common, complex disease that follows a chronic relapsing course and significantly affects the quality of life of patients. Skin barrier dysfunction and inflammatory processes induce and aggravate this skin condition. Proper use of an emollient for hydration is a keystone of AD treatment. Bee venom is known to have anti-inflammatory effects and has been widely used in traditional medicine to treat various inflammatory disorders.

OBJECTIVE

To find out the beneficial effect of an emollient containing bee venom in the treatment of patients with AD.

METHODS

This study included 136 patients with AD who were randomized to receive either an emollient containing bee venom and silk-protein or a vehicle that was identical except for the bee venom for 4 weeks. The patients were instructed to apply the emollient twice daily on their entire body and not to use other medications, including topicals, during the course of the study. The eczema area and severity index (EASI) score, transepidermal water loss, and visual analogue scale (VAS) score of itching were evaluated at the first visit and after 2 and 4 weeks. The investigator global assessment was evaluated at 2 and 4 weeks after the application of emollient containing bee venom or vehicle.

RESULTS

Patients applying emollient containing bee venom showed significantly lower EASI score and VAS value compared to patients applying emollient without bee venom.

CONCLUSION

Emollient containing bee venom is a safe and effective option for patients with AD.

Associations of TNFα -308G>A, TNFα -238G>A, IL-1α -889C>T and IL-10 -1082G>A Genetic Polymorphisms with Atopic Diseases: Asthma, Rhinitis and Dermatitis

BACKGROUND

Polymorphisms of cytokine genes are an interesting focus for association studies involving atopic diseases due to their role in immune cell communications during inflammation. The aim of this study was to investigate associations of TNFα -308G>A, TNFα -238G>A, IL-1α -889C>T and IL-10 -1082G>A polymorphisms with atopic diseases with adjustment for confounding lifestyle and environmental factors.

METHODS

This study was performed on 356 Croatian students. The diagnosis of atopic asthma, atopic rhinitis and atopic dermatitis was based on symptoms reported by the modified International Study of Asthma and Allergies in Childhood questionnaire and a positive skin prick test (SPT) to at least one common inhalatory allergen. Genetic polymorphisms were genotyped using the polymerase chain reaction-based technique. The influence of personal (gender, body mass index, parental history of atopic disease), lifestyle (cigarette smoking, pet ownership) and environmental (urban/rural residency, residency in continental/Mediterranean region) factors reported in the questionnaire was investigated by univariate and multivariate analysis.

RESULTS

Compared to the control subjects, univariate analysis showed a significant negative association of the TNFα -308G>A polymorphism with atopic asthma, atopic dermatitis, asthma and skin symptoms and positive SPT. These observations were confirmed in a multivariate model only for atopic dermatitis and skin symptoms (atopic dermatitis: OR = 0.27; 95% CI 0.07-1.00; p = 0.050; skin symptoms: OR = 0.29; 95% CI 0.10-0.83; p = 0.021).

CONCLUSIONS

The results indicate a protective role of TNFα -308G>A genetic polymorphisms regarding atopic dermatitis and skin symptoms even after controlling for personal, lifestyle and environmental factors. Further studies are needed to elucidate the molecular patterns of this association in atopic dermatitis and other chronic inflammatory skin disorders.

Oral Administration of Achyranthis radix Extract Prevents TMA-induced Allergic Contact Dermatitis by Regulating Th2 Cytokine and Chemokine Production in Vivo

Allergic contact dermatitis (ACD) remains a major skin disease in many countries, necessitating the discovery of novel and effective anti-ACD agents. In this study, we investigated the preventive effects of Achyranthis radix extract (AcRE) on trimellitic anhydride (TMA)-induced dermatitis and the potential mechanism of action involved. Oral administration of AcRE and prednisolone (PS) significantly suppressed TMA-induced increases in ear and epidermal thickness, and IgE expression. In addition, abnormal expression of IL-1β and TNF-α protein and mRNA was also significantly attenuated by oral administration of AcRE. Treatment with AcRE also significantly suppressed TMA-induced IL-4 and IL-13 cytokines and mRNA expression in vivo. Moreover, AcRE strongly suppressed TMA-induced IL-4 and IL-5 production in draining lymph nodes, as well as OVA-induced IL-4 and IL-5 expression in primary cultured splenocytes. Interestingly, AcRE suppressed IL-4-induced STAT6 phosphorylation in both primary cultured splenocytes and HaCaT cells, and TMA-induced GATA3 mRNA expression ex vivo. AcRE also suppressed TMA-mediated CCL11 and IL-4-induced CCL26 mRNA expression and infiltration of CCR3 positive cells. The major compounds from AcRE were identified as gentisic acid (0.64 ± 0.2 μg/g dry weight of AcRE), protocatechuic acid (2.69 ± 0.1 μg/g dry weight of AcRE), 4-hydroxybenzoic acid (5.59 ± 0.3 μg/g dry weight of AcRE), caffeic acid (4.21 ± 0.1 μg/g dry weight of AcRE), and ferulic acid (14.78 ± 0.4 ± 0.3 μg/g dry weight of AcRE). Taken together, these results suggest that AcRE has potential for development as an agent to prevent and treat allergic contact dermatitis.

Dexamethasone but not tacrolimus suppresses TNF-α-induced thymic stromal lymphopoietin expression in lesional keratinocytes of atopic dermatitis model

BACKGROUND

Thymic stromal lymphopoietin (TSLP) initiates the Th2-type allergic inflammation, and is thought to play an important role in the pathogenesis of atopic dermatitis (AD). TNF-α is a key cytokine which is involved in the pathophysiology of various inflammatory diseases, and the expression level is elevated in the sera and skin of patients with AD. In addition, TNF-α has been reported to induce TSLP expression in epidermal keratinocytes. Topical glucocorticoids and calcineurin inhibitors are safe and effective agents for AD, but the effects of these agents on TNF-α-induced TSLP expression are not fully understood.

OBJECTIVE

To investigate whether the glucocorticosteroid dexamethasone and the calcineurin inhibitor tacrolimus could affect TSLP expression induced by TNF-α in lesional keratinocytes of AD.

METHODS

The effects of topical dexamethasone and tacrolimus on TSLP expression were evaluated in an AD mouse model induced by repeated 2,4,6-trinitro-1-chlorobenzene application. Co-immunostaining for TSLP and TNF-α was performed using skin samples from AD patients and the mouse model. Normal human epidermal keratinocytes (NHEKs) were cultured with dexamethasone or tacrolimus in the presence of TNF-α to analyze TSLP expression.

RESULTS

Topical application of dexamethasone but not tacrolimus repressed TSLP expression in the mouse model. TSLP and TNF-α showed similar distribution pattern in epidermal keratinocytes of AD lesions and the mouse model. TSLP expression was induced by TNF-α via NF-κB in a dose-dependent and an autocrine and/or paracrine manner in NHEKs, which was significantly suppressed by dexamethasone but not by tacrolimus. Similarly to TSLP expression, IL-6, TNF-α, IL-8, and IL-36γ expression induced by TNF-α were significantly suppressed by dexamethasone but not by tacrolimus in NHEKs.

CONCLUSION

Dexamethasone but not tacrolimus suppresses the TSLP expression induced by TNF-α in lesional keratinocytes of AD model. Our observations uncover the unreported functional difference between topical glucocorticosteroids and calcineurin inhibitors in cutaneous inflammatory diseases.

Free IL-12p40 monomer is a polyfunctional adaptor for generating novel IL-12-like heterodimers extracellularly

IL-12p40 partners with the p35 and p19 polypeptides to generate the heterodimeric cytokines IL-12 and IL-23, respectively. These cytokines play critical and distinct roles in host defense. The assembly of these heterodimers is thought to take place within the cell, resulting in the secretion of fully functional cytokines. Although the p40 subunit alone can also be rapidly secreted in response to inflammatory signals, its biological significance remains unclear. In this article, we show that the secreted p40 monomer can generate de novo IL-12-like activities by combining extracellularly with p35 released from other cells. Surprisingly, an unbiased proteomic analysis reveals multiple such extracellular binding partners for p40 in the serum of mice after an endotoxin challenge. We biochemically validate the binding of one of these novel partners, the CD5 Ag-like glycoprotein, to the p40 monomer. Nevertheless, the assembled p40-CD5L heterodimer does not recapitulate the biological activity of IL-12. These findings underscore the plasticity of secreted free p40 monomer, suggesting that p40 functions as an adaptor that is able to generate multiple de novo composites in combination with other locally available polypeptide partners after secretion.

Filaggrin loss-of-function mutations are associated with enhanced expression of IL-1 cytokines in the stratum corneum of patients with atopic dermatitis and in a murine model of filaggrin deficiency

Background

Filaggrin (FLG) mutations result in reduced stratum corneum (SC) natural moisturizing factor (NMF) components and consequent increased SC pH. Because higher pH activates SC protease activity, we hypothesized an enhanced release of proinflammatory IL-1 cytokines from corneocytes in patients with atopic dermatitis (AD) with FLG mutations (AD_FLG) compared with that seen in patients with AD without these mutations (AD_NON-FLG).

Objectives

We sought to investigate SC IL-1 cytokine profiles in the uninvolved skin of controls and patients with AD_FLG versus patients with AD_NON-FLG. We also sought to examine the same profiles in a murine model of filaggrin deficiency (Flg^ft/Flg^ft [Flg^delAPfal] mice).

Methods

One hundred thirty-seven patients were studied. NMF levels were ascertained using confocal Raman spectroscopy; transepidermal water loss and skin surface pH were measured. IL-1α, IL-1β, IL-18, IL-1 receptor antagonist (IL-1RA), and IL-8 levels were determined in SC tape strips from 93 patients. All subjects were screened for 9 FLG mutations. Flg^ft/Flg^ft (Flg^delAPfal) mice, separated from maFlg^ft/maFlg^ft (flaky tail) mice, were used for the preparation and culture of primary murine keratinocytes and as a source of murine skin. RT-PCR was performed using primers specific for murine IL-1α, IL-1β, and IL-1RA.

Results

SC IL-1 levels were increased in patients with AD_FLG; these levels were inversely correlated with NMF levels. NMF values were also inversely correlated with skin surface pH. Skin and keratinocytes from Flg^ft/Flg^ft mice had upregulated expression of IL-1β and IL-1RA mRNA.

Conclusions

AD_FLG is associated with an increased SC IL-1 cytokine profile; this profile is also seen in a murine homologue of filaggrin deficiency. These findings might have importance in understanding the influence of FLG mutations on the inflammasome in the pathogenesis of AD and help individualize therapeutic approaches.

The epidermis as an adjuvant

It is now clear that the epidermis has an active role in local immune responses in the skin. Keratinocytes are involved early in inflammation by providing first-line innate mechanisms and, in addition, can contribute to adaptive immune responses that may be associated with clinical disease. Moreover, keratinocytes are capable of enhancing and shaping the outcome of inflammation in response to stimuli and promoting particular types of immune bias. Through understanding the underlying mechanisms, the role of keratinocytes in disease pathogenesis will be further defined, which is likely to lead to the identification of potential targets for prophylactic or therapeutic intervention.

Cigarette smoking may modify the risk of depression in eczema among adults: a preliminary study using NHANES 2005-2006

BACKGROUND

Eczema has been shown to be associated with an increased risk of depression. However, the effect of cigarette smoking on the association between eczema and depression remains unclear.

OBJECTIVES

In this study, we investigated whether smoking behaviour and tobacco exposure influence the association between eczema and depression.

METHODS

This was a population-based cross-sectional study. Subjects (287 eczema patients and 40 patients with depression, out of a total of 2974 subjects in the database) were from the National Health and Nutrition Examination Survey 2005-2006, aged between 20 and 59 years. Lifetime presence of eczema was obtained by self-reporting questionnaires, and depression was assessed by the Patient Health Questionnaire. Smoking status was determined by self-report and serum cotinine levels. Univariate and multivariate logistic regressions were used to assess the association between eczema and depression with and without adjusting for smoking behaviour. Stratified analysis was also performed according to smoking status.

RESULTS

Eczema was significantly associated with depression (adjusted OR: 2.12; 95% CI: 1.59-2.83). This association persisted after additionally adjusting for smoking status. In stratified analysis, the association between eczema and depression was higher and stronger among current smokers than never smokers, former smokers and passive smokers.

CONCLUSION

Our findings indicated that cigarette smoking may modify the risk of depression in eczema. We suggested cessation of smoking in eczema patients to decrease the risk of this psychiatric co-morbidity.

Interleukin (IL)-31 induces pro-inflammatory cytokines in human monocytes and macrophages following stimulation with staphylococcal exotoxins

BACKGROUND

IL-31 is a cytokine expressed by T cells following activation with cytokines or staphylococcal exotoxins. A major function of IL-31 in atopic dermatitis (AD) is the induction of pruritus in the skin via the IL-31 receptor on sensory nerve cells. However, the regulation of the IL-31 receptor and pro-inflammatory functions of IL-31 in human monocytes and monocyte-derived cells are yet to be studied in detail.

OBJECTIVE

To investigate the regulation and function of IL-31 receptors in resting and activated human monocytes, macrophages and dendritic cells.

METHODS

Human monocytes, macrophages and dendritic cells were stimulated with staphylococcal exotoxins (SEB, alpha-toxin) or cytokines (IFN-gamma, IL-13). IL-31RA expression and regulation were then investigated at both the mRNA and the protein level. Subsequently, functional effects of IL-31 stimulation on cytokine secretion were measured at the protein level.

RESULTS

Staphylococcal exotoxins significantly up-regulated IL-31RA expression on monocytes and macrophages but not on dendritic cells at both the mRNA and the protein level. IL-31 enhanced the secretion of IL-1beta, IL-6 and IL-18 and up-regulated CD86 expression. In patients with AD, functional IL-31RA was also detected following stimulation of PBMC with IFN-gamma. However, this was not observed in healthy individuals.

CONCLUSION

IL-31 induces pro-inflammatory effects in activated human monocytes and macrophages. This may have implications for cutaneous inflammation in eczema where an over-expression of IL-31 has been described previously. Moreover, our findings provide a new link between staphylococcal colonization and the worsening of inflammation via IL-31. Further therapeutic considerations may include IL-31 as a target in AD.

IL-1 and Allergy

IL-1 is a well-characterized proinflammatory cytokine that is involved in host defense and autoimmune diseases. IL-1 can promote activation of T cells, including Th1 cells, Th2 cells and Th17 cells, and B cells, suggesting that IL-1 may contribute to the development of various types of T-cell-mediated diseases. This report reviews and discusses the role of IL-1 in the pathogenesis of allergic diseases based on studies using IL-1-related gene-deficient mice.

Overexpression of IL-1alpha in skin differentially modulates the immune response to scarification with vaccinia virus

Transepidermal inoculation of vaccinia virus (VV), or scarification, has been used effectively for the induction of specific and long-lasting immunity to smallpox and is superior to other routes of immunization. Scarification of individuals with atopic skin disease or immune deficiency, however, can lead to persistent viral replication and result in significant morbidity and mortality. These effects of scarification presumably reflect the unique immunological properties of skin and the immune cells resident in, or recruited to, the site of inoculation. To explore these phenomena, we utilized transgenic mice engineered to overexpress IL-1alpha, a critical mediator of cutaneous inflammation, in the epidermis. Following scarification with VV, both transgenic and wild-type mice develop local pox. At high doses of VV, IL-1alpha transgenic mice recruited immune cells to the inoculation site more rapidly and demonstrated enhanced T-cell and humoral immune responses. At limiting doses, however, IL-1alpha transgenic mice could effectively control virus replication without formation of pox lesions or activation of a memory response. This study suggests that IL-1 might be useful as an adjuvant to enhance antiviral immunity and promote safer vaccination strategies; however, understanding the balance of IL-1 effects on innate and adaptive immune functions will be critical to achieve optimal results.

ADAM10-mediated E-cadherin release is regulated by proinflammatory cytokines and modulates keratinocyte cohesion in eczematous dermatitis

Acute eczema is an inflammatory skin disease characterized by the formation of small intraepidermal blisters, reduction of the adhesion molecule E-cadherin from the keratinocyte surface, and impaired keratinocyte cohesion. Here, we reveal that the disintegrin and metalloprotease ADAM10 is critically involved in regulating E-cadherin cell-surface expression in cultured primary human keratinocytes and in diseased human skin. Proinflammatory cytokines, transforming growth factor-beta, and lipopolysaccharide led to increased release of soluble E-cadherin by activating mitogen-activated protein kinase signaling in cultured keratinocytes. Moreover, these stimuli decreased the amount of pro-ADAM10 and increased the level of the active protease, leading to loss of E-cadherin from the cell surface and decreased keratinocyte cohesion. In situ examination and immunoblot analyses of E-cadherin and ADAM10 expression in lesional skin of eczema revealed that the reduction of E-cadherin expression in areas of blister formation closely correlated with increased level of ADAM10 expression and elevated E-cadherin shedding. Our data suggest that ADAM10-mediated E-cadherin proteolysis leads to the impaired cohesion of keratinocytes observed in eczematous dermatitis and provide previously unreported insights into the understanding of the molecular mechanisms involved in inflammatory diseases with loss in epithelial integrity.

Evaluation of the expression of P-selectin, ICAM-1, and TNF-alpha in bacteria-free lesional skin of atopic dogs with low-to-mild inflammation

Canine atopic dermatitis (AD) is a pruritic skin condition that shares many clinical and pathophysiological features with its human counterpart. A major therapeutic challenge of AD is the control of the skin inflammatory process. A detailed knowledge of the pro-inflammatory molecules involved in cell recruitment in AD would allow for a better control of the disease. We thus have studied the protein expression of P-selectin, ICAM-1 and TNF-alpha in the lesional and non-lesional skin of atopic dogs that had been treated for bacterial infections. Despite a low-to-mild inflammatory process, P-selectin protein was clearly upregulated in the lesional skin areas when compared with non-lesional skin (four-fold average increase). This P-selectin upregulation was accompanied by signs of functional changes such as increased cell margination, and membrane-associated protein expression. Although the expression of ICAM-1 and TNF-alpha was not enhanced in the lesional versus the non-lesional skin, there was a trend towards a correlated upregulation of both molecules. Further studies will help elucidate the significance of the substantial overexpression of P-selectin in canine AD, in particular in a scenario where bacterial antigens are not contributing as pro-inflammatory stimuli.

Increased interleukin-1β mRNA expression in skin biopsies of horses with Culicoides hypersensitivity following challenge with Culicoides nubeculosus extract

Interleukin-1beta (IL-1beta) is a primary cytokine of the skin that has a pivotal role in keratinocyte differentiation, epidermal wound healing and host defense. Pathological increase of cutaneous IL-1beta is associated with edema formation, epidermal hyperproliferation and atopic dermatitis in humans. However, in horses the role of cutaneous IL-1beta in edema formation and allergic skin disease has not been characterised so far. Particularly in Culicoides hypersensitivity (CHS), intradermal injection of Culicoides extract may be associated with enhanced transcription of local IL-1beta. To examine the mRNA expression of IL-1beta and its receptor antagonist IL-1RA in the skin of horses, biopsy specimens of horses affected and non-affected by CHS prior and following intradermal challenge with a commercial C. nubeculosus extract were examined. Our hypothesis was that cutaneous IL-1beta mRNA was significantly upregulated in horses with CHS in response to Culicoides allergen. Biopsies were taken from sites prior to and 4 h following intradermal challenge with C. nubeculosus extract. In order to obtain reliable data, real time PCR was performed and genes of interest were normalized using three different housekeeping genes, beta-actin, GAPDH, beta-2-microglobulin. No significant difference was detected in non-challenged cutaneous IL-1beta mRNA and IL-1RA mRNA levels between CHS affected and non-affected horses. Intradermal injection of C. nubeculosus extract resulted in local upregulation of IL-1beta mRNA both in horses with typical history, characteristic clinical signs for CHS and a positive intradermal skin test (IDT), and non-affected horses with a negative IDT. However, the difference in prior and post challenged site IL-1beta mRNA levels only reached statistical significance in the affected horses (p=0.01 versus 0.7). In contrast, IL-1RA mRNA levels did not demonstrate any modification following intradermal injection with C. nubeculosus in either group. In contrast to human atopic dermatitis, clinically normal skin of horses affected by CHS is not characterized by increased maintenance levels of IL-1beta mRNA. C. nubeculosus stimulates local IL-1beta transcription in all horses independent from disease, but the extent of upregulation from basal levels only reaches statistical significance in horses affected by CHS and active stage of disease.

T-cell control of IL-12p75 production

It is currently thought that IL-12, produced by dendritic cells (DC) early after stimulation by bacterial pathogens or lipopolysaccharide (LPS), acts as a pro-inflammatory cytokine bridging the innate and adaptive immune responses. We found, however, that it is only the p40 subunit and not the IL-12p75 heterodimer that is secreted early in copious amounts in response to LPS. Neither naïve T cells, nor a variety of microbial products, were able to induce IL-12p75 production unless the DC were conditioned by the presence of interferon-gamma (IFN-gamma) or by encounter with previously activated T cells. The inability of naïve T cells or of bacterial products to induce IL-12 argues against its early role as the initiator of innate and adaptive immune responses.

Cellular and cytokine kinetics after epicutaneous allergen challenge (atopy patch testing) with house dust mites in high-IgE beagles

The cellular and cytokine dynamics of reactions triggered by atopy patch testing with house dust mites were studied in six high-IgE beagles. Sites were scored and biopsied at 6, 24, 48, and 96 h, and samples were processed for histopathology, immunohistochemistry, and polymerase chain reaction (PCR). All dogs developed positive reactions at some point in time. Mean clinical scores were significantly higher than baseline at 24, 48, and 96 h. Clinically, one of six dogs had a positive reaction at 6 h; two of six reacted at 24 and 48 h, and five of six at 96 h. Histologically, superficial perivascular mononuclear and granulocytic dermatitis developed (5/6) after 6 h, and progressed in severity at 24 h (6/6). Additionally, at 48 h epidermal spongiosis, hyperplasia and pustules developed (5/6), and were marked at 96 h (6/6). At and beyond 6 h, progressive CD1c-positive epidermal Langerhans cell hyperplasia with cluster formation and dermal dendritic cell infiltration was noted. Cutaneous infiltration of CD3-positive T lymphocytes with epidermal clusters developed over time. mRNA expression for the cytokines gamma-interferon (gamma-IFN), interleukin-6 (IL-6), IL-12p35, IL-13, IL-18, and thymus and activation regulated chemokine (TARC) exhibited significant increases during the challenge compared to baseline, but there was no appreciable alteration in expression for tumour necrosis factor-alpha (TNF-alpha), IL-12p40, IL-10, regulated on activation normal T-cell expressed and secreted (RANTES), IL-5, IL-2, IL-4, and IL-8. No correlation was detected between clinical scores and cytokines. It is concluded that IL-6 plays a role in early reactions followed by an increase of TARC and IL-13, while IL-18 progressively increases in later reactions.

Recent developments in the treatment of adult atopic dermatitis

Atopic dermatitis is a common inflammatory skin condition with increasing incidence in recent decades. The mainstay of treatment has been the combination of emollients and topical corticosteroids, with the addition of systemic therapies in severe cases. New drugs such as the topical calcineurin inhibitors have shown promise in treating mild-to-severe atopic dermatitis. Other novel therapies that have been reported in the literature include leukotriene antagonists, monoclonal antibodies such as infliximab, leflunomide, recombinant interferon gamma and intravenous immunoglobulin. This review will focus on the treatment of adult atopic dermatitis.

Leishmania infantum released proteins specifically regulate cytokine expression and production patterns by CD4+ and CD8+ T cells

Specific immune responses by CD4+ and CD8+ T cells, from two infected mice strains (BALB/c and C57BL/6), induced by High, Inter and Low protein fractions released by Leishmania infantum, were assessed through the evaluation of IL-12, IFN-gamma and IL-10 mRNA by real-time PCR and respective protein production by ELISA. During infection establishment, High and Inter fractions directed both mice strains T cells subsets to increase the production of IFN-gamma, associated to IL-12 release. Later on, parasite replication augmented in BALB/c and stabilised in C57BL/6 mice. Inter fraction induced CD4+ T cells to maintain IFN-gamma production, with the simultaneous release of IL-12 by both cell subsets in BALB/c mice and by CD8+ T cells in C57BL/6 mice. These observations suggested a prophylactic potential for Inter fraction which was able to induce Th1 response with IL-12 involvement, required for the maintenance of memory cells, in mice strains with different parasitic evolution.

Infliximab in the treatment of moderate to severe atopic dermatitis

BACKGROUND

Chronic use of standard therapies for atopic dermatitis (AD) is associated with variable efficacy and potential side effects. Targeted therapeutic approaches, such as the inhibition of tumor necrosis factor-alpha, may be a novel option.

OBJECTIVE

This investigator-initiated, open, prospective, single-center, pilot study was conducted to evaluate the long-term efficacy and safety of infliximab in patients with AD.

METHODS

Nine patients with moderate or severe AD were enrolled. AD in these patients was resistant to conventional therapy. Infliximab 5 mg/kg was administered by intravenous infusion at weeks 0, 2, 6, 14, 22, 30, and 38, and patients were followed for 46 weeks.

RESULTS

Induction therapy with infliximab significantly improved all clinical parameters, but this improvement was not sustained through maintenance therapy. Only two patients with severe AD achieved an excellent clinical response by 46 weeks.

CONCLUSIONS

Infliximab monotherapy may be an additional therapeutic option for the management of refractory severe AD.

Topical nanocrystalline silver cream suppresses inflammatory cytokines and induces apoptosis of inflammatory cells in a murine model of allergic contact dermatitis

BACKGROUND

Nanocrystalline silver has both antimicrobial and anti-inflammatory properties. However, the exact mechanisms underlying these activities are not known.

OBJECTIVES

The objectives of this study were to assess the anti-inflammatory effects of nanocrystalline silver using a murine model of allergic contact dermatitis, compare the effects with those of tacrolimus and a high potency steroid, and to relate the effects to modulation of pro-inflammatory cytokines and apoptosis of inflammatory cells.

METHODS

Dermatitis was induced on the ears of BALB/c mice using dinitrofluorobenzene. Topical treatment, including vehicles, 1% nanocrystalline silver cream, tacrolimus ointment and a high potency steroid, was applied once a day for 4 days. Ear swelling was measured and the erythema was evaluated daily. After 4 days of treatment the mice were killed and samples from the ears were collected for histological and immunohistochemical examination, terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labelling (TUNEL) staining and extraction of total RNA for reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

Significant reductions of ear swelling, erythema and histopathological inflammation in mice ears were observed after 4 days of treatment with 1% nanocrystalline silver cream, tacrolimus ointment or a high potency steroid with no significant difference among them. Both RT-PCR and immunohistochemical staining of sections from ear biopsies demonstrated that nanocrystalline silver, tacrolimus and steroid significantly suppressed the expression of tumour necrosis factor (TNF)-alpha and interleukin (IL)-12. TUNEL staining demonstrated a significant increase in the numbers of apoptotic cells in material from the group treated with nanocrystalline silver when compared with that from groups treated with vehicle, tacrolimus or steroid.

CONCLUSIONS

This study demonstrates that nanocrystalline silver inhibits allergic contact dermatitis in mice, similar to steroid and tacrolimus. Nanocrystalline silver suppresses the expression of TNF-alpha and IL-12 and induces apoptosis of inflammatory cells; mechanisms by which nanocrystalline silver may exert its anti-inflammatory effects.

Glucocorticoids for Human Skin: New Aspects of the Mechanism of Action

Topical glucocorticoids have always been considered first-line drugs for inflammatory diseases of the skin and bronchial system. Applied systemically, glucocorticoids are used for severe inflammatory and immunological diseases and the inhibition of transplant rejection. Owing to the progress in molecular pharmacology, the knowledge of the mechanism of action has increased during the last years. Besides distinct genomic targets, which are due to the activation of specific cytoplasmatic receptors resulting in the (trans-) activation or (trans-) repression of target genes, there are non-genomic effects on the basis of the interference with membrane-associated receptors as well as with membrane lipids. In fact, various glucocorticoids appear to differ with respect to the relative influence on these targets. Thus, the extended knowledge of glucocorticoid-induced cellular signalling should allow the design and development of even more specifically acting drugs - as it has been obtained with other steroids, e.g. estrogens for osteoporosis prevention.

The maturation-dependent production of interleukin-16 is impaired in monocyte-derived dendritic cells from atopic dermatitis patients but is restored by inflammatory cytokines TNF-alpha and IL-1beta

BACKGROUND

Maturation of dendritic cells (DCs) influences important DC functions such as production of cytokines. Recently, DCs were identified as a source of interleukin-16 (IL-16), a chemotactic factor for DCs themselves, CD4+ T cells, and eosinophils. There is evidence that DC-derived IL-16 may contribute to the pathogenesis of atopic dermatitis (AD).

OBJECTIVE

To investigate the production of IL-16 during differentiation of monocytes into DCs in healthy individuals and patients with AD.

METHODS

IL-16 production was investigated by quantitative real-time RT-PCR, intracellular cytokine staining, immunoblotting, and ELISA.

RESULTS

DCs generated from peripheral monocytes by 5-day culture in the presence of IL-4 and granulocyte/macrophage colony-stimulating factor acquired the capability to synthesize, store, and secrete IL-16. Storage and release of IL-16 was further enhanced during final DC maturation induced by additional 3-day culture with tumor necrosis factor-alpha (TNF-alpha) and monocyte-conditioned medium. Maturation, as determined by up-regulation of CD83 and CD86 surface expression, and production of IL-16, but not production of IL-10 and IL-12p40 was impaired in day 8 DCs derived from AD patients compared to those from healthy donors. Stimulation of day 8 DCs from AD patients with TNF-alpha and IL-1beta enhanced the expression of CD83 and CD86 and restored the production of IL-16.

CONCLUSIONS

Signals involved in the activation and maturation of DCs enhance their capacity to produce IL-16. Functional abnormalities present in patients with AD at the monocyte level may account for impaired maturation and IL-16 production of monocyte-derived DCs.

Modulation of Immune Functions by Foods

Evidence is rapidly accumulating as to the beneficial effects of foods. However, it is not always clear whether the information is based on data evaluated impartially in a scientific fashion. Human research into whether foods modulate immune functions in either intervention studies or randomized controlled trials can be classified into three categories according to the physical state of subjects enrolled for investigation: (i) studies examining the effect of foods in healthy individuals; (ii) studies analyzing the effect of foods on patients with hypersensitivity; and (iii) studies checking the effect of foods on immunocompromized subjects, including patients who had undergone surgical resection of cancer and newborns. The systematization of reported studies has made it reasonable to conclude that foods are able to modulate immune functions manifesting as either innate immunity (phagocytic activity, NK cell activity) or acquired immunity (T cell response, antibody production). Moreover, improvement of immune functions by foods can normalize the physical state of allergic patients or cancer patients, and may reduce the risk of diseases in healthy individuals. Therefore, it is valuable to assess the immune-modulating abilities of foods by measuring at least one parameter of either innate or acquired immunity.

Subclinical activation of latent cytomegalovirus (CMV) infection and anti-CMV immune response in patients with atopic dermatitis

BACKGROUND

Microbiological infections are considered to be of pathophysiological importance in atopic dermatitis (AD). As yet, no information is available regarding cytomegalovirus (CMV) infection in this disease. This, however, is of interest because of the high prevalence of latent infections in the general population, the frequent reactivation in inflammatory diseases, and the immunomodulating capacity of CMV.

OBJECTIVES

To investigate the prevalence of latent CMV infection, the frequency of active CMV infection, and the immune response to CMV in patients with moderate to severe AD. Methods To detect active infection we analysed CMV antigen expression by peripheral blood mononuclear cells (PBMC) from 27 patients with moderate to severe AD in comparison with 53 healthy volunteers. We used three monoclonal antibodies recognizing different CMV-encoded antigens and immunocytological staining (alkaline phosphatase-antialkaline phosphatase technique).

RESULTS

Patients with AD had a higher mean frequency of CMV-positive PBMC: 2.25 per 10 000 vs. 0.74 per 10 000 in controls (P = 0.001) as well as a higher incidence of CMV antigenaemia: 29.6% vs. 7.5% (P < 0.01). Seropositivity for anti-CMV IgG antibodies indicated subclinical activation of latent infection. Remarkably, a clearance of CMV antigenaemia was observed during anti-eczematous treatment. Significantly higher plasma levels of tumour necrosis factor-alpha, which is involved in CMV reactivation, and interleukin-12, which is crucial for an antiviral cellular immune response, were observed in AD patients in comparison with healthy volunteers. Furthermore, a significantly enhanced frequency of circulating activated HLA-DR+ T cells especially in CMV-seropositive AD patients (19.3% vs. 13.5% in seronegative AD patients vs. 10.2% in controls) suggested that the active CMV infection triggers a cellular immune response. This was also supported by a high frequency of CMV-specific interferon-gamma-producing T cells in CMV-seropositive patients with AD.

CONCLUSIONS

Our data suggest that active, subclinical CMV infection is more frequent in patients with moderate to severe AD and may have immunopathophysiological relevance.

Immunopathological studies on feline cutaneous and (muco)cutaneous mycobacteriosis

Eight cases of feline (muco)cutaneous mycobacteriosis were studied to identify the causative agent and examine for phenotype and functional characteristics (expression of interleukin (IL)-1beta, IL-6, IL-12, tumour necrosis factor-alpha and inducible nitric oxide synthase) of the inflammatory cells. Polymerase chain reaction and sequencing identified the causative agents as Mycobacterium tuberculosis or M. avium complex in each four cases. Lesions were characterised by pyogranulomatous infiltration, with variability in the presence and size of necrotic areas, the presence of multinucleated giant cells and the degree of lymphocyte infiltration. Macrophages were positive for myeloid/histiocyte antigen (calprotectin), suggesting they represented freshly recruited monocytes; further differentiation to epithelioid cells and multinucleated giant cells was associated with loss of the myeloid/histiocyte antigen. Lymphocytes were found disseminated in the infiltrate (predominantly T cells) and as B cell-dominated accumulations mainly in the periphery of the lesions. Acid-fast bacilli were numerous. In M. tuberculosis complex infection, extracellular bacilli were most prominent, whereas in M. avium complex infection, bacilli were mainly located intracellularly. All cytokines examined as well as inducible nitric oxide synthase (iNOS) were variably expressed by macrophages, epithelioid cells and multinucleated giant cells. Expression was most intense in degenerating macrophages loaded with intracellular bacilli, but was also seen cell-free within necrotic areas. The intense induction of cytokine and iNOS expression especially in infected macrophages suggests a relatively low virulence for these infectious agents in cats. Furthermore, the confinement of the bacilli to lesions indicates a successful response to infection.

Variability in responsiveness to irritants: thoughts on possible underlying mechanisms

Patch testing with chemical irritants almost always produces a striking variability in the intensity of reaction between individuals, even amongst normal, healthy subjects. Whilst there have been many attempts to define factors which predispose to heightened or, conversely, to diminished reactivity, the underlying cellular mechanisms responsible for the variability remain poorly understood. In this review, a number of possible explanations are proposed, with a particular emphasis on those which relate to the influence of pre-existing disease or to the genetic regulation of certain immunological and inflammatory processes.

IL-12: the role of p40 versus p75

Interleukin (IL)-12p75 is a heterodimeric cytokine composed of the product of two different genes that specify p35 and p40 subunits. The prevailing view is that IL-12 acts as a proinflammatory cytokine that bridges the innate and adaptive immune responses and skews T-cell reactivity toward a TH1 cytokine pattern. Though the terms IL-12 and IL-12p40 are often used interchangeably, and measurements of the p40 chain are often interpreted as measurements of the intact p75 heterodimer, such interchangeable usage may be incorrect. In the following discussion, I will delineate an alternative hypothesis for the roles of the p40 and p75 proteins, suggesting specifically, that: (1) in vivo, secretion of free p40 precedes that of p75 in response to pathogens; (2) induction of p40 is a T-independent response by antigen presenting cells (APCs) to early host-pathogen interactions; and (3) IL-12p75 is a late product, whose induction requires T-dependent signals. It is made as a result, rather than as a cause, of TH1 differentiation. Thus, it is the p40 protein, either alone or paired with other polypeptides, rather than p75, that acts as an interface between the innate and adaptive immune responses.

The effects of capsaicin topical therapy in dogs with atopic dermatitis: a randomized, double-blinded, placebo-controlled, cross-over clinical trial

The efficacy of twice daily topical application of capsaicin (0.025%) for the management of pruritus in dogs with atopic dermatitis (AD) was evaluated in double-blinded, placebo-controlled study. Twelve dogs with AD were randomly assigned to either 0.025% capsaicin or vehicle lotion applied twice daily for 6 weeks. After a 4-week wash-out period, treatments were switched. Significant improvement was reported by owners (P = 0.0006), but not by investigators. Owners noted temporary worsening of pruritus after the first week of capsaicin therapy. Overall capsaicin was well tolerated. Substance P (SP) concentrations in the skin did not correlate with the severity of the pruritus and did not change significantly over time and between treatments. Lesional skin had less SP than nonlesional skin (P = 0.03). These observations suggest that topical capsaicin should be further evaluated as an adjunctive antipruritic agent in dogs with AD.

Expression of Th1, Th2 and immunosuppressive cytokine gene transcripts in canine atopic dermatitis

BACKGROUND

Atopic dermatitis is a common inflammatory skin disease of humans and dogs. Human atopic dermatitis is associated with Th2-type responses, although Th1 cytokines can be identified in chronic lesions. In contrast, tolerance to environmental allergens in healthy individuals is mediated by regulatory T cells.

OBJECTIVE

This study examined the expression of the immunosuppressive cytokines TGF-beta and IL-10, the Th2-type cytokines IL-4 and IL-6, and the Th1-type cytokines IFN-gamma, TNF-alpha, IL-2, IL-12p35 and IL-12p40, in canine atopic dermatitis.

MATERIALS AND METHODS

RNA was isolated from lesional atopic, non-lesional atopic and healthy canine skin samples. Semi-quantitative reverse transcriptase polymerase chain reactions (RT-PCRs) were carried out using specific primers and one-way analyses of variance used to compare cytokine expression in each group.

RESULTS

Canine atopic dermatitis was associated with over-expression of IL-4 mRNA and reduced transcription of TGF-beta compared with healthy skin (P < 0.05). Higher levels of IFN-gamma, TNF-alpha and IL-2 mRNA were seen in lesional compared with non-lesional and healthy skin (P < 0.05). There were no significant differences in IL-10, IL-6, IL-12p35 or IL-12p40 transcription between the three groups.

CONCLUSIONS

This is the first report to demonstrate that canine atopic dermatitis is associated with over-production of IL-4. Clinical tolerance in healthy individuals appears to be associated with TGF-beta, although it is unclear if this reflects an active mechanism or simply non-responsiveness of the immune system. Th1 cytokines may be induced by subsequent self-trauma and secondary infections in atopic skin. We believe that these results better characterize spontaneously occurring canine atopic dermatitis. We further propose that this should be investigated as a possible animal model of human atopic dermatitis.

Positive patch tests with a dermatophagoides mix relate to an increased responsiveness to standard patch test allergens

The diagnostic meaningfulness of patch tests with house dust mite allergens is still questionable. Our own impression has been that positive results with a dermatophagoides mix may occur preferentially in patients with a generally enhanced responsiveness to contact allergens. To check this, all of our patients allocated to patch testing with the standard series were additionally patch tested with a dermatophagoides mix by the same technique that was used for standard contact allergens. Out of 571 patients tested, 188 showed delayed responses to this mix that were indistinguishable from typical allergic patch test reactions but of no apparent clinical relevance. No relationship was found between positive dermatophagoides patch tests and an atopic disposition of the patients or characteristics of their eczema. However, 64.4% of the patients with a positive dermatophagoides patch test showed a response to at least 1 contact allergen of the standard series, compared to only 56.4% of the patients without a positive dermatophagoides reaction (p < 0.05). The reactivity to the mite mix was not related to the responsiveness towards any particular contact allergens. We suppose that some unidentified factors may contribute to positive reactions to the dermatophagoides mix that may also favour an enhanced general responsiveness to contact allergens.