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As the body's first line of defense, the skin is the organ most frequently exposed to chemicals present in personal hygiene products, household products, or materials used in the work environment. In this context, skin disorders account for more than 40 % of all occupational and work-related diseases, constituting a significant public health burden. Among skin disorders, allergic contact dermatitis (ACD) is the most prevalent occupational disease and the most common form of immunotoxicity in humans. ACD is a T-cell-mediated skin inflammation resulting from the priming and expansion of allergen-specific CD4 + and CD8 + T cells. The clinical condition is characterized by local skin rash, itchiness, redness, swelling, and lesions, being mainly diagnosed by the patch test. Upon ACD diagnosis, avoiding the exposure to the triggering allergen is the mainstay of treatment to prevent future flares. In cases where avoidance is not possible, the use of a standard of care interim treatments such as steroid creams or ointments, barrier creams, and moisturizers are strongly recommended to alleviate symptoms. In this review, we sought to provide the reader with an overview of the pathophysiology of ACD as well as the currently available pharmacological treatment options. Furthermore, a comprehensive outline of several preventive strategies is also provided., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

A peptide reactivity assay with an activation component was developed for use in screening chemicals for skin sensitization potential. A horseradish peroxidase-hydrogen peroxide (HRP/P) oxidation system was incorporated into the assay for characterizing reactivity of hapten and pre-/prohapten sensitizers. The assay, named the Peroxidase Peptide Reactivity Assay (PPRA) had a predictive accuracy of 83% (relative to the local lymph node assay) with the original protocol and prediction model. However, apparent false positives attributed to cysteine depletion at relatively high chemical concentrations and, for some chemicals expected to react with the -NH2 group of lysine, little to no depletion of the lysine peptide were observed. To improve the PPRA, cysteine peptide reactions with and without HRP/P were modified by increasing the number of test concentrations and refining their range. In addition, removal of DL-dithiothreitol from the reaction without HRP/P increased cysteine depletion and improved detection of reactive aldehydes and thiazolines without compromising the assay's ability to detect prohaptens. Modification of the lysine reaction mixture by changing the buffer from 0.1 M ammonium acetate buffer (pH 10.2) to 0.1 M phosphate buffer (pH 7.4) and increasing the level of organic solvent from 1% to 25% resulted in increased lysine depletion for known lysine reactive chemicals. Refinement of the prediction model improved the sensitivity, specificity, and accuracy for hazard identification. These changes resulted in significant improvement of the PPRA making it is a reliable method for predicting the skin sensitization potential of all chemicals, including pre-/prohaptens and directly reactive haptens., (© The Author(s) 2020. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

We examined anti-inflammatory potency of hybrid peptide-PK20, composed of neurotensin (NT) and endomorphin-2 (EM-2) pharmacophores in a murine model of non-atopic asthma induced by skin sensitization with 2,4-dinitrofluorobenzene and intratracheal challenge of cognate hapten. Mice received intraperitoneally PK20, equimolar mixture of its structural elements (MIX), dexamethasone (DEX), or NaCl. Twenty-four hours following hapten challenge, the measurements of airway responsiveness to methacholine were taken. Bronchoalveolar lavage (BALF) and lungs were collected for further analyses. Treatment with PK20, similarly to dexamethasone, reduced infiltration of inflammatory cells, concentration of mouse mast cell protease, IL-1β, IL-12p40, IL-17A, CXCL1, RANTES in lungs and IL-1α, IL-2, IL-13, and TNF-α in BALF. Simple mixture of NT and EM-2 moieties was less potent. PK20, DEX, and MIX significantly decreased malondialdehyde level and secretory phospholipase 2 activity in lungs. Intensity of NF-κB immunoreactivity was diminished only after PK20 and DEX treatments. Neither PK20 nor mixture of its pharmacophores were as effective as DEX in alleviating airway hyperresponsiveness. PK20 effectively inhibited hapten-induced inflammation and mediator and signaling pathways in a manner seen with dexamethasone. Improved anti-inflammatory potency of the hybrid over the mixture of its moieties shows its preponderance and might pose a promising tool in modulating inflammation in asthma.

Neurotensin (NT) demonstrates ambiguous activity on inflammatory processes. The present study was undertaken to test the potential anti-inflammatory activity of NT in a murine model of non-atopic asthma and to establish the contribution of NTR1 receptors. Asthma was induced in BALB/c mice by skin sensitization with dinitrofluorobenzene followed by intratracheal hapten provocation. The mice were treated intraperitoneally with NT, SR 142948 (NTR1 receptor antagonist) + NT or NaCl. Twenty-four hours after the challenge, airway responsiveness to nebulized methacholine was measured. Bronchoalveolar lavage fluid (BALF) and lungs were collected for biochemical and immunohistological analysis. NT alleviated airway hyperreactivity and reduced the number of inflammatory cells in BALF. These beneficial effects were inhibited by pretreatment with the NTR1 antagonist. Additionally, NT reduced levels of IL-13 and TNF-α in BALF and IL-17A, IL12p40, RANTES, mouse mast cell protease and malondialdehyde in lung homogenates. SR 142948 reverted only a post-NT TNF-α decrease. NT exhibited anti-inflammatory activity in the hapten-induced asthma. Reduced leukocyte accumulation and airway hyperresponsiveness indicate that this beneficial NT action is mediated through NTR1 receptors. A lack of effect by the NTR1 blockade on mast cell activation, oxidative stress marker and pro-inflammatory cytokine production suggests that other pathways can be involved, which requires further research.

Drug development involves pharmacometric experiments in animals. Such experiments should limit animal pain and stress. Conventional murine models of atopic dermatitis (AD) used in drug development are generated by weekly painting of hapten on dorsal skin for 5 weeks. The present study aimed to develop a protocol that involves less animal distress. The experiments focused on serum total IgE levels, which are a marker of AD. The conventional protocol induced ever rising IgE levels. Experiments with extended intervals between sensitizations showed that IgE peaked ~5 days after the second sensitization, after which it returned to the control level within 12-19 days. An additional third sensitization on day 28 further increased the serum IgE level. In the 4-5 days after the second sensitization, the dorsal skin exhibited typical AD-like lesions with edema, scabs, epithelial-cell hypertrophy, marked mast-cell and lymphocyte infiltration of dermis, and increased IL-4, IL-6, IL-10, IL-1β, IL-17A, IFN-γ and TNF-α expression. Thus, two 2,4-dinitrofluorobenzene sensitizations yield a murine AD model in less than 20 days. This study shows that animal model protocols used in drug development can be fine-tuned so that they remain effective yet cause animals less stress and pain.

Background: The current European baseline series consists of 30 allergens, and was last updated in 2015., Objectives: To use data from the European Surveillance System on Contact Allergies (ESSCA) to propose an extension to the European baseline series in response to changes in environmental exposures., Methods: Data from departmental and national extensions to the baseline series, together with some temporary additions from departments contributing to the ESSCA, were collated during 2013-2014., Results: In total, 31689 patients were patch tested in 46 European departments. Many departments and national groups already consider the current European baseline series to be a suboptimal screen, and use their own extensions to it. The haptens tested are heterogeneous, although there are some consistent themes. Potential haptens to include in an extension to the European baseline series comprise sodium metabisulfite, formaldehyde-releasing preservatives, additional markers of fragrance allergy, propolis, Compositae mix, and 2-hydroxyethyl methacrylate., Conclusion: In combination with other published work from the ESSCA, changes to the current European baseline series are proposed for discussion. As well as addition of the allergens listed above, it is suggested that primin and clioquinol should be deleted from the series, owing to reduced environmental exposure., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Contact allergy to chloroprene rubber products is well known. Thiourea compounds are considered the cause of allergy. Diethylthiourea commonly occurs in this type of product and can decompose to the sensitizer ethyl isothiocyanate., Objectives: To investigate the clinical importance of degradation products and metabolites from organic thioureas in contact allergy to chloroprene rubber with a focus on isothiocyanates and isocyanates., Methods: Patients with contact allergy to diphenylthiourea were patch tested with phenyl isothiocyanate and phenyl isocyanate. Patients with known contact allergy to diethylthiourea were retested with diethylthiourea, while chemical analyses of their chloroprene rubber products were performed. The stability of diethylthiourea, diphenylthiourea and dibutylthiourea in patch-test preparations was investigated. Liquid chromatography/mass spectrometry and solid-phase microextraction/gas chromatography were used for determination of organic thioureas and isothiocyanates., Results: All patients allergic to diphenylthiourea reacted to phenyl isothiocyanate, two of eight reacted to phenyl isocyanate and six of eight reacted to diphenylthiourea. Four patients allergic to diethylthiourea reacted at retest; diethylthiourea was detected in all chloroprene rubber samples, with levels of 2-1200 nmol cm -2 . At 35 °C, ethyl isothiocyanate was emitted from all samples. Patch-test preparations of diethylthiourea, diphenylthiourea and dibutylthiourea all emitted the corresponding isothiocyanate, with diethylthiourea showing the highest rate of isothiocyanate emission., Conclusions: Thiourea compounds are degraded to isothiocyanates, which are generally strong or extreme sensitizers, thus acting as prehaptens. This process occurs in both chloroprene rubber products and patch-test preparations. Positive reactions to phenyl isocyanate indicate cutaneous metabolism, as the only known source of exposure to phenyl isocyanate is through bioactivation of diphenylthiourea., (© 2017 British Association of Dermatologists.)

The optimal recognition of penicillin determinants, including amoxicillin (AX), by specific IgE antibodies is widely believed to require covalent binding to a carrier molecule. The nature of the carrier and its contribution to the antigenic determinant is not well known. Here we aimed to evaluate the specific-IgE recognition of different AX-derived structures. We studied patients with immediate hypersensitivity reactions to AX, classified as selective or cross-reactors to penicillins. Competitive immunoassays were performed using AX itself, amoxicilloic acid, AX bound to butylamine (AXO-BA) or to human serum albumin (AXO-HSA) in the fluid phase, as inhibitors, and amoxicilloyl-poli-L-lysine (AXO-PLL) in the solid-phase. Two distinct patterns of AX recognition by IgE were found: Group A showed a higher recognition of AX itself and AX-modified components of low molecular weights, whilst Group B showed similar recognition of both unconjugated and conjugated AX. Amoxicilloic acid was poorly recognized in both groups, which reinforces the need for AX conjugation to a carrier for optimal recognition. Remarkably, IgE recognition in Group A (selective responders to AX) is influenced by the mode of binding and/or the nature of the carrier; whereas IgE in Group B (cross-responders to penicillins) recognizes AX independently of the nature of the carrier.

Contact sensitizers induce phenotypic and functional changes in dendritic cells (DC) that enhance their antigen-presenting capacity and, ultimately, modulate the T cell response. To evaluate if there is a similar effect of drugs causing T-cell-mediated cutaneous adverse drug reactions (CADR), we studied the in vitro effect of drugs on THP-1 cells, a cell line widely used to evaluate the early molecular and cellular events triggered by contact sensitizers. The effect of allopurinol, oxypurinol, ampicillin, amoxicillin, carbamazepine and sodium valproate, at EC30 concentrations, was evaluated on p38 MAPK activation, by Western Blot, and on the expression of genes coding for DC maturation markers, pro-inflammatory cytokine/chemokines and hemeoxygenase 1 (HMOX1), by real-time RT-PCR. Results were compared with lipopolysaccharide (LPS), a DC maturation stimulus, and the strong contact sensitizer, 1-fluoro-2,4-dinitrobenzene (DNFB). All drugs studied significantly upregulated HMOX1 gene transcription and all, except the anticonvulsants, also upregulated IL8. Allopurinol and oxypurinol showed the most intense effect, in a magnitude similar to DNFB and superior to betalactams. Transcription of CD40, IL12B and CXCL10 genes by drugs was more irregular. Moreover, like DNFB, all drugs activated p38 MAPK, although significantly only for oxypurinol. Like contact sensitizers, drugs that cause non-immediate CADR activate THP-1 cells in vitro, using different signalling pathways and affecting gene transcription with an intensity that may reflect the frequency and severity of the CADR they cause. Direct activation of antigen-presenting DC by systemic drugs may be an important early step in the pathophysiology of non-immediate CADR., (Copyright © 2014 John Wiley & Sons, Ltd.)

Low-molecular weight chemicals (haptens) include a large group of chemical compounds occurring in work environment, items of everyday use (cleaning products, clothing, footwear, gloves, furniture), jewelry (earrings, bracelets), drugs, especially in cosmetics. They cause type IV hypersensitive reactions. During the induction phase of delayed-type hypersensitivity, haptens form complexes with skin proteins. After internalization through antigen presenting cells, they are bound to MHC class II molecules. Next, they are exposed against specific T-lymphocytes, what triggers activation of Th1 cells mainly. After repeating exposition to that hapten, during effector phase, Th1 induce production of cytokines affecting non-specific inflammatory cells. Usually, it causes contact dermatitis. However, occasionally incidence of immediate generalized reactions after contact with some kinds of haptens is noticed. A question arises, how the hapten does induce symptoms which are typical for anaphylaxis, and what contributes to amplification of this mechanism. It seems that this phenomenon arises from pathomechanism occurring in contact urticaria syndrome in which an anaphylactic reaction may be caused either by contact of sensitized skin with protein antigens, high-molecular weight allergens, or haptens. One of the hypotheses indicates the leading role of basophiles in this process. Their contact with haptens, may cause to release mediators of immediate allergic reaction (histamine, eicosanoids) and to produce cytokines corresponding to Th2 cells profile. Furthermore, Th17 lymphocytes secreting pro-inflammatory interleukin-17 might be engaged into amplifying hypersensitivity into immediate reactions and regulatory T-cells may play role in the process, due to insufficient control of the activity of effector cells.

Thrombocytopenia is commonly seen in laboratory findings, especially in critically ill patients. Although the incidence is rare, drug-induced immune thrombocytopenia (DITP) is a serious complication that is often overlooked as a cause of thrombocytopenia. Over the last century, extensive research and data collection have been done in an attempt to better characterize DITP. Heparin-induced thrombocytopenia is the most common DITP and has distinct pathogenesis, diagnosis, and treatment options. However, other offending medications are less well known and have triggered many questions and constant search for answers. This review will discuss both drug-induced immune-mediated and nonimmune-mediated thrombocytopenias, with a focus on immune-mediated processes. Thrombocytopenia caused by chemotherapy will not be discussed in this article., (© The Author(s) 2014.)

Background: The possible impact of metal release from coronary artery stents has, with their increased use, become a concern., Objectives: To study in vitro metal release in biologically relevant milieu from coronary stents made of different alloys., Materials and Method: Coronary stents in common use in a department of cardiology at the time of the study were tested. A previously described in vitro technique was used, whereby the stents were kept in the extraction media for a week. Two different extraction media were used to show the necessity of studying the actual biological surrounding of the implant when metal release is investigated. Metal release was determined with atomic absorption spectrometry., Results: In this study, we show metal release from stents after immersion in extraction media of artificial sweat and cysteine solution, as illustrative media., Conclusion: Metal release from coronary stents is shown. The magnitude of release is influenced by several factors. The extent to which metal release in vitro has potential biological effects, in terms of elicitation of an allergic reaction or induction of sensitization, in vivo needs to be explored. However, as metal release from an implant in a biologically appropriate medium has been established, better risk assessments in relation to delayed hypersensitivity may be undertaken., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Folate immune (EC90 vaccine with GPI-0100 adjuvant followed by EC17) is a novel folate-targeted hapten immunotherapy designed to exploit the overexpression of folate receptors on renal cell carcinoma (RCC) cells. In this open-label, phase I/II clinical study, we report the safety, pharmacokinetics, and antitumor activity of folate immune with concurrent interleukin-2 (IL-2) and interferon-α (IFN-α) in patients with recurrent or metastatic RCC. Twenty-four patients were enrolled. Following 2 phase I cohorts of 6 patients each, we extended the study to 12 additional patients: 18 received weekly vaccination of 1.2 mg of EC90 with 3.0 mg of GPI-0100 adjuvant for 4 weeks. Beginning on cycle 1, day 8, 0.3 mg/kg of EC17 was administered once daily, 5 days per week (Monday-Friday) for 4 consecutive weeks. Beginning on cycle 1, day 15, IL-2 and IFN-α were administered at doses of 12 and 3.0 MIU, respectively, after the EC17 dose, 3 times per week (Monday, Wednesday, and Friday) for 3 weeks. In cycle 2, IL-2 and IFN-α, doses of 7.0 and 3.0 MIU, respectively, were administered 3 days per week (Monday, Wednesday, and Friday) for 4 consecutive weeks. No dose-limiting toxicities were observed. Most adverse events reported were grade 1 or 2, with only twelve grade ≥3 toxicities reported. Sixteen patients had progressive disease, 7 patients were observed to have stable disease, and 1 patient achieved a partial response lasting 71 days. Overall, folate immune plus low-dose IFN-α and IL-2 was safe and well tolerated with some observed clinical activity.

Background: Until recently, it was thought that in patients with atopic dermatitis (AD), contact hypersensitivity phenomenon occurs less frequently than in the general population because of the impaired cellular immune response., Objective: The aim of this study was to evaluate the incidence of contact dermatitis in the population of patients with AD., Methods: A total of 39 patients with clinical diagnosis of AD during remission were patch tested with 28 European Baseline Series allergens and 8 corticosteroids allergens in different concentrations and media. Twenty-nine (74.3%) patients were female and 10 (25.6%) patients were male. Thirty-three (84.6%) patients were older than 18 years. The mean duration of AD was 20 years., Results: Nineteen (48%) patients had an allergic reaction to at least 1 European Standard Series allergen, and 5 (12.8%) patients had an allergic reaction to at least 1 corticosteroid. The most common allergens giving positive results were nickel sulfate (28.2%), potassium dichromate (20.5%), cobalt chloride (12.8%), and phenylenediamine, budesonide, betamethasone, clobetasol, and dexamethasone (7.7% each)., Conclusions: This study shows that allergic contact hypersensitivity is common among patients with AD and affects up to 40% of cases. Contact allergy to corticosteroids becomes a serious problem in the treatment of chronic inflammatory dermatoses such as AD.

Thrombocytopenia is caused by immune reactions elicited by diverse drugs in clinical practice. The activity of the drug-dependent antibodies produces a marked decrease in blood platelets and a risk of serious bleeding. Understanding of the cellular mechanisms that drive drug-induced thrombocytopenia has advanced recently but there is still a need for improved laboratory tests and treatment options. This article provides an overview of the different types of drug-induced thrombocytopenia, discusses potential pathologic mechanisms, and considers diagnostic methods and treatment options., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Background: Although atopic disease is associated with protein allergy, its relationship with chemicals (haptens/contact allergens and irritants) is less clearly defined. The 'hapten-atopy' hypothesis, whereby significant hapten and irritant exposure during times of natural T helper (Th)2 bias (pregnancy and first year of life) promotes the development of atopy and atopic disease in the resulting child, has been previously proposed. Supporting evidence includes the practice of repeated cutaneous application of haptens in generating animal models of atopic dermatitis, and the observation of a significant increase in atopic disease in children born to mothers with occupations associated with high chemical exposure during pregnancy., Objectives: To observe the relationship between personal chemical exposure and atopic disease in a particular case series., Methods: We report a case series of exacerbation of atopic dermatitis after repeated cutaneous chemical exposure., Results: Most of the patients had atopic dermatitis in young childhood that had resolved. However, after repeated chemical exposure, either occupationally as an adult or after starting to use cosmetics as a teenager, there was clear exacerbation of atopic dermatitis. Patch tests gave negative results in most cases., Conclusions: We propose that repeated exposure to chemicals in patients with an atopic background can occasionally lead to reactivation of atopic dermatitis., (© 2013 John Wiley & Sons A/S.)

In the past decade, mechanisms underlying allergic contact dermatitis have been intensively investigated by using contact hypersensitivity (CHS) models in mice. However, the regulatory mechanisms, which could be applicable for the treatment of allergic contact dermatitis, are still largely unknown. To determine the roles of B and T lymphocyte attenuator (BTLA), a CD28 family coinhibitory receptor, in hapten-induced CHS, BTLA-deficient (BTLA(-/-)) mice and littermate wild-type (WT) mice were subjected to DNFB-induced CHS, severe combined immunodeficient (SCID) mice were injected with CD4(+) T cells, and CD8(+) T cells from either WT mice or BTLA(-/-) mice were subjected to CHS. BTLA(-/-) mice showed enhanced DNFB-induced CHS and proliferation and IFN-γ production of CD8(+) T cells as compared with WT mice. SCID mice injected with WT CD4(+) T cells and BTLA(-/-) CD8(+) T cells exhibited more severe CHS as compared with those injected with WT CD4(+) T cells and WT CD8(+) T cells. On the other hand, SCID mice injected with BTLA(-/-) CD4(+) T cells and WT CD8(+) T cells exhibited similar CHS to those injected with WT CD4(+) T cells and WT CD8(+) T cells. Finally, to evaluate the therapeutic potential of an agonistic agent for BTLA on CHS, the effects of an agonistic anti-BTLA antibody (6A6) on CHS were examined. In vivo injection of 6A6 suppressed DNFB-induced CHS and IFN-γ production of CD8(+) T cells. Taken together, these results suggest that stimulation of BTLA with agonistic agents has therapeutic potential in CHS.

Metal hypersensitivity is a common immune disorder. Human immune systems mount the allergic attacks on metal ions through skin contacts, lung inhalation and metal-containing artificial body implants. The consequences can be simple annoyances to life-threatening systemic illness. Allergic hyper-reactivities to nickel (Ni) and beryllium (Be) are the best-studied human metal hypersensitivities. Ni-contact dermatitis affects 10 % of the human population, whereas Be compounds are the culprits of chronic Be disease (CBD). αβ T cells (T cells) play a crucial role in these hypersensitivity reactions. Metal ions work as haptens and bind to the surface of major histocompatibility complex (MHC) and peptide complex. This modifies the binding surface of MHC and triggers the immune response of T cells. Metal-specific αβ T cell receptors (TCRs) are usually MHC restricted, especially MHC class II (MHCII) restricted. Numerous models have been proposed, yet the mechanisms and molecular basis of metal hypersensitivity remain elusive. Recently, we determined the crystal structures of the Ni and Be presenting human MHCII molecules, HLA-DR52c (DRA*0101, DRB3*0301) and HLA-DP2 (DPA1*0103, DPB1*0201). These structures revealed unusual features of MHCII molecules and shed light on how metal ions are recognized by T cells.

Recent changes in regulatory restrictions and social views against animal testing have accelerated development of reliable alternative tests for predicting skin sensitizing potential and potency of many chemicals. Lately, a test battery integrated with different in vitro tests has been suggested as a better approach than just one in vitro test for replacing animal tests. In this study, we created a dataset of 101 test chemicals with LLNA, human cell line activation test (h-CLAT), direct peptide reactivity assay (DPRA) and in silico prediction system. The results of these tests were converted into scores of 0-2 and the sum of individual scores provided the accuracy of 85% and 71% for the potential and potency prediction, compared with LLNA. Likewise, the straightforward tiered system of h-CLAT and DPRA provided the accuracy of 86% and 73%. Additionally, the tiered system showed a higher sensitivity (96%) compared with h-CLAT alone, indicating that sensitizers would be detected with higher reliability in the tiered system. Our data not only demonstrates that h-CLAT can be part of a test battery with other methods but also supports the practical utility of a tiered system when h-CLAT and DPRA are the first screening methods for skin sensitization., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Patients suffering from ulcerative colitis (UC) exhibit chronic colonic inflammation caused by a dysregulated mucosal immune response and epithelial barrier disruption. Th2 cytokines, including IL-13, have been implicated in the pathogenesis of UC. IL-13 induces phosphorylation of STAT6, and we previously demonstrated increased epithelial p-STAT6 in children with UC. In this study, we investigated the role of STAT6 in oxazolone colitis, a murine model of UC, by inducing colitis in STAT6-deficient (STAT6(-/-)) and wild type (WT) mice. We observed increased epithelial cell, T cell, macrophage, and NKT cell STAT6 phosphorylation, as well as increased p-STAT6(+) IL-13-producing NKT cells, in colitic WT mice. Colitis was attenuated in STAT6(-/-) mice, with improvements in weight, colon length, and histopathology. There was decreased induction of the pore-forming tight junction protein claudin-2 in STAT6(-/-) mice. Similarly, short hairpin RNA STAT6 knockdown reduced claudin-2 induction and transepithelial resistance decrease in IL-13-treated human T84 cells. Tissue expression of IL-13, IFN-γ, IL-17, and IL-10 mRNA was similarly induced in WT and STAT6(-/-) colitic mice; however, we observed increased mRNA expression for the Th2-inducing cytokines IL-33 and thymic stromal lymphopoietin in WT mice with colitis, which was abrogated in STAT6(-/-) mice. Mesenteric lymph node cells from STAT6(-/-) mice with colitis exhibited reduced secretion of IL-4, IL-5, IL-13, and IFN-γ. IL-33 augmented mesenteric lymph node cell secretion of IL-5, IL-13, IL-6, and IFN-γ. These data implicate STAT6 in the pathogenesis of colitis in vivo with important roles in altering epithelial barrier function and regulating Th2-inducing cytokine production.

Background: Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by pruritic and eczematous skin lesions. In this study, AD-like disease was induced in NC/Nga mice so as to evaluate the anti-allergic effects of Vernonia amygdalina leaf extracts (VAM)., Methods: Forty NC/Nga mice were purchased for each of the two protocols (prophylactic and curative) of the study. Mice were randomly divided in groups of five or six after sensitization with 5% trinitrochlorobenzene (TNCB): aqueous extracts (VAM1), methanolic extracts (VAM2), hydrocortisone (HCT), buffer for the control (TNCB) and the normal mice (NORM) groups., Results: As for HCT, VAM1 and VAM2-pretreated mice showed significantly lower number of scratching behavior episodes (p < 0.01; vs. TNCB) following TNCB challenge. In addition, VAM1, VAM2 exerted a significant inhibitory effect on the development of AD skin symptoms (vs. TNCB group; p < 0.001), the production of IgE, TNF-alpha (p < 0.05), IL-5 and IFN-gamma (p < 0.01) (vs. TNCB group) and on the increase in ear thickness (p < 0.05) in prophylactic protocol. In the AD curative protocol, topical VAM1, VAM2 markedly improved skin lesions such as erythema/hemorrhage (p < 0.05), scaling/dryness, erosion/excoriation (p < 0.01) (vs. TNCB mice). Furthermore, a significant decrease in ear thickness was noted in VAM1, VAM2, HCT groups (vs. TNCB group; p < 0.05) as well as the serum total IgE, MCP-1 (p < 0.01) and eotaxin (p < 0.05). VAM2 also improved chronic eczema dermatitis skin symptoms in a patient., Conclusions: Results from this report suggest that VAM extracts, known as ERK pathway inhibitor, prevent and improve atopic/eczema dermatitis syndrome.

Background: Linalool is a common fragrance terpene that, in pure form, is not allergenic or is a very weak allergen. However, linalool autoxidizes on air exposure, and the oxidation products can cause contact allergy. In a Swedish study, oxidized linalool 6.0% in petrolatum (pet.) gave 5% positive patch test reactions in 2500 dermatitis patients., Objectives: To investigate whether oxidized linalool 6%, with a stable concentration of the main haptens, the linalool hydroperoxides (Lin-OOHs) in pet., could be a useful tool for the detection of contact allergy in an international setting. Methods. Oxidized linalool 6.0% (Lin-OOHs 1%) pet. was tested in 2900 consecutive dermatitis patients in Denmark, the United Kingdom, Singapore, Spain, Sweden, and Australia., Results: Overall, 6.9% (range 3-13%) of the patients showed positive patch test reactions to oxidized linalool. Doubtful reactions were found in 9.2% of the patients (range 0-36%). Few irritant reactions were seen., Conclusions: In an international setting, oxidized linalool has been shown to be a common allergen. Oxidized linalool 6.0% (Lin-OOHs 1%) pet. is a useful, standardized and stable tool for the detection of contact allergy in dermatitis patients. Many patients showing positive patch test reactions to oxidized linalool would not have been informed of their fragrance allergy if this specific test had not been performed., (© 2012 John Wiley & Sons A/S.)

Some chemicals contribute to the development of allergies by increasing the immunogenicity of other allergens. We have demonstrated that several phthalate esters, including dibutyl phthalate (DBP), enhance skin sensitization to fluorescein isothiocyanate (FITC) in a mouse contact hypersensitivity model, in which the T-helper type 2 (Th2) response is essential. On the other hand, some phthalate esters were found to activate transient receptor potential ankyrin 1 (TRPA1) cation channels on sensory neurons. We then found a positive correlation between the enhancing effects of several types of phthalate esters on skin sensitization to FITC and their ability to activate TRPA1. Here we examined the involvement of TRPA1 in sensitization to FITC by using TRPA1 agonists other than phthalate esters. During skin sensitization to FITC, the TRPA1 agonists (menthol, carvacrol, cinnamaldehyde and DBP) augmented the ear-swelling response as well as trafficking of FITC-presenting dendritic cells to draining lymph nodes. We confirmed that these TRPA1 agonists induced calcium influx into TRPA1-expressing Chinese hamster ovary (CHO) cells. We also found that TRPA1 antagonist HC-030031 inhibited DBP-induced calcium influx into TRPA1-expressing CHO cells. After pretreatment with this antagonist upon skin sensitization to FITC, the enhancing effect of DBP on sensitization was suppressed. These results suggest that TRPA1 activation will become a useful marker to find chemicals that facilitate sensitization in combination with other immunogenic haptens., (Copyright © 2012 Elsevier Inc. All rights reserved.)

The term 'immunotherapy' refers to treating diseases by inducing, enhancing or suppressing immune responses. As allergy is an excessive, detrimental immune reaction to otherwise harmless environmental substances, immunotherapy of allergic disease is aimed at the induction of tolerance toward sensitizing antigens. This article focuses on the historical developments, present state and future outlook for immunotherapy with haptens as a therapeutic modality for allergic contact dermatitis. Inspired by the effectiveness of immunotherapy in respiratory allergies, attempts were undertaken at curing allergic contact dermatitis by means of controlled administration of the sensitizing haptens. Animal and human experiments confirmed that tolerance to haptens can be induced most effectively when the induction of tolerance precedes attempted sensitization. In real life, however, therapy is sought by people who are already sensitized and an effective reversal of hypersensitivity seems more difficult to achieve. Decades of research on Rhus hypersensitivity led to a conclusion that immunotherapy can suppress Rhus dermatitis, however, only to a limited degree, for a short period of time, and at a high risk of side effects, which makes this method therapeutically unprofitable. Methodological problems with most available studies of immunotherapy of contact allergy to nickel make any definite conclusions impossible at this stage.

The antiallergic activity of rhubarb and its constituents, anthraquinones, has been reported previously. For further evaluation of the antiallergic activity, a 70% ethanol extract of the rhizomes of Rheum tanguticum (RTE) was prepared and its inhibitory activity on an animal model of atopic dermatitis (AD) was examined for the first time. Oral administration of RTE (30-300 mg/kg/day) for 5 weeks significantly inhibited hapten-induced dermatitis in NC/Nga mice based on the skin severity score. In addition, treatment with RTE at 100 mg/kg/day also reduced the numbers of white blood cells, neutrophils and eosinophils in the blood, and led to a significant reduction in the IgE concentration in the serum. In rat basophilic leukemia (RBL)-1 cells, RTE inhibited 5-lipoxygenase (5-LOX)-catalysed leukotriene production (IC(50)  = 43.6 µg/mL). Among the anthraquinone derivatives isolated, emodin strongly inhibited this parameter (IC(50)  = 4.3 µM). Taken together, these findings suggest that rhubarb exerts inhibitory activity against AD, and that the 5-LOX inhibitory activity of its major constituent, emodin, may contribute to this inhibitory action., (Copyright © 2011 John Wiley & Sons, Ltd.)

Background: CD4(+)CD25(+) regulatory T (Treg) cells are involved in the downmodulation of numerous immune responses to pathogens, tumors, or allergens., Objective: In this study, we further characterized the nature of Treg cells that control skin inflammatory reactions to haptens., Methods: In a model of contact hypersensitivity to 2,4-dinitro-fluorobenzene, we have investigated the phenotype, the specificity, and the origin of Treg cells that modulate the priming of effector CD8(+) T cells responsible for the development of the pathology., Results: 2,4-Dinitrofluorobenzene immunization induced a population of CD4(+)CD25(+) Treg cells that controlled CD8(+) T-cell effector responses in a hapten-specific manner in vivo. High levels of inducible costimulator (ICOS) expression defined a population of CD4(+)CD25(+)FoxP3(+) (forkhead box protein 3) Treg cells that presented superior suppressive activity. Importantly, ICOS(+) Treg cells were distinguishable from all other FoxP3(+) Treg cells by the expression of IL-10, IL-17, and IFN-gamma. Hapten-specific Treg cells proliferating in response to their cognate antigen in vivo predominantly displayed a CD25(+)FoxP3(+)ICOS(+) phenotype. By using reporter mice, we showed that ICOS(+) Treg cells derived from the expansion of natural CD4(+)FoxP3(+) Treg cells rather than generation of adaptive Treg cells. Furthermore, the generation of ICOS(+) Treg cells depended on innate cells rather than the effector CD8(+) T-cell population., Conclusion: Taken together, our data show that a population of CD4(+)CD25(+)FoxP3(+) T cells upregulates ICOS on in vivo sensitization and specifically suppresses hapten-reactive CD8(+) T cells both in vivo and in vitro., (Copyright 2010 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.)

The protein adduct carboxyethylpyrrole (CEP) is present in age-related macular degeneration (AMD) eye tissue and in the blood of AMD patients at higher levels than found in age-matched non-AMD tissues. Autoantibodies to CEP are also higher in AMD blood samples than in controls. To test the hypothesis that this hapten is causally involved in initiating an inflammatory response in AMD, we immunized C57BL/6J mice with mouse serum albumin (MSA) adducted with CEP. Immunized mice develop antibodies to CEP, fix complement component-3 in Bruch's membrane, accumulate drusen below the retinal pigment epithelium during aging, show decreased a- and b-wave amplitudes in response to light, and develop lesions in the retinal pigment epithelium mimicking geographic atrophy, the blinding end-stage condition characteristic of the dry form of AMD. Inflammatory cells are present in the region of lesions and may be actively involved in the pathology observed. We conclude that early immunization of mice with CEP-adducted MSA sensitizes these animals to the ongoing production of CEP adducts in the outer retina where DHA is abundant and the conditions for oxidative damage are permissive. In response to this early sensitization, the immune system mounts a complement-mediated attack on the cells of the outer retina where CEP adducts are formed. This animal model for AMD is the first that was developed from an inflammatory signal discovered in eye tissue and blood from AMD patients. It provides a novel opportunity for dissecting the early pathology of AMD and the immune response contributing to this disorder. The availability of a mouse with a mechanistically based AMD-like disease that progresses rapidly is highly desirable. Such a model will allow for the efficient preclinical testing of the much-needed therapeutics quickly and inexpensively.

Background: Linalool is a widely used fragrance terpene. Pure linalool is not allergenic or a very weak allergen, but autoxidizes on air exposure and the oxidation products can cause contact allergy. Oxidized (ox.) linalool has previously been patch tested at a concentration of 2.0% in petrolatum (pet.) in 1511 patients, and 1.3% positive patch test reactions were observed., Objective: To investigate the optimal patch test concentration for detection of contact allergy to ox. linalool., Methods: Four concentrations of ox. linalool (2.0%, 4.0%, 6.0%, 11.0% pet.) were tested in 3418 consecutive dermatitis patients., Results: Ox. linalool 2.0%, 4.0%, 6.0%, and 11.0% pet. detected positive patch test reactions in 0.83%, 3.2%, 5.3%, and 7.2% of the tested patients, respectively. The doubtful reactions increased with rising concentrations but relatively less, giving 5.1%, 6.4%, and 7.3% doubtful reactions, respectively, for ox. linalool 4.0%, 6.0%, and 11.0% pet. Few irritative reactions were seen., Conclusions: Raising the patch test concentration for ox. linalool gave a better detection of contact allergy, as many as 5-7% positive patch test reactions were detected. We suggest a patch test concentration of ox. linalool 6.0% pet. for future patch testing, giving a dose per unit area of 2.4 mg/cm(2) when 20 mg test substance is tested in small Finn Chambers.

Cancer vaccine/immunotherapy rarely involves systemic administration of an immunogenic compound to an actively immunized host. We have developed such a strategy that utilizes folate to deliver antigenic haptens [e.g., fluorescein (FITC) and dinitrophenyl] to folate receptor-positive tumors in a hapten-pre-vaccinated host. Here, we investigated the safety of this novel approach and developed strategies to prevent drug-related hypersensitivity. Using FITC as the model hapten, we identified a potential source of allergic species in folate-FITC preparations by LC-MS/MS. In mice and guinea pigs, we tested the significance of this impurity by passive cutaneous anaphylaxis and active systemic anaphylaxis assays. We studied the effect of immunogen (e.g., KLH-FITC) dose and derived a desensitization regimen that was further evaluated in a murine tumor model. Administration of folate-FITC with low multi-haptenated contaminants (e.g. bis-FITC) resulted in hypersensitivity in underimmunized animals. However, this drug-related hypersensitivity may be independently prevented by (1) increasing the immunogen dose and/or (2) desensitizing animals with folate-FITC during vaccination. In addition, such manipulation in vivo did not appear to negatively alter the effectiveness of immunotherapy. This study provided confidence on the safety of folate-hapten-targeted cancer immunotherapy in an actively immunized host.

Signaling through tumor necrosis factor receptor 1 (TNFR1) controls bacterial infections and the induction of inflammatory Th1 cell-mediated autoimmune diseases. By dissecting Th1 cell-mediated delayed-type hypersensitivity responses (DTHRs) into single steps, we localized a central defect to the missing TNFR1 expression by endothelial cells (ECs). Adoptive transfer and mast cell knockin experiments into Kit(W)/Kit(W-v), TNF(-/-), and TNFR1(-/-) mice showed that the signaling defect exclusively affects mast cell-EC interactions but not T cells or antigen-presenting cells. As a consequence, TNFR1(-/-) mice had strongly reduced mRNA and protein expression of P-selectin, E-selectin, ICAM-1, and VCAM-1 during DTHR elicitation. In consequence, intravital fluorescence microscopy revealed up to 80% reduction of leukocyte rolling and firm adhesion in TNFR1(-/-) mice. As substitution of TNF(-/-) mice with TNF-producing mast cells fully restored DTHR in these mice, signaling of mast cell-derived TNF through TNFR1-expressing ECs is essential for the recruitment of leukocytes into sites of inflammation.

We have found that fermented barley extract (FBE), prepared from barley shochu residue, alleviates allergic rhinitis in OVA-sensitized mice. In this study, we examined to determine whether FBE suppresses the development of atopic dermatitis (AD)-like skin lesions in NC/Nga mice. The development of AD-like skin lesions in a 5% FBE containing diet group was significantly inhibited, and scratching behavior, one of aggravating factors, was also suppressed. Neither serum immunoglobulin E (IgE) levels nor interleukin (IL)-4 production by spleen cells in the 5% FBE diet group was found to be significantly reduced. On the other hand, interferon-gamma (IFN-gamma) and IL-17 production by spleen cells in the 5% FBE diet group was significantly reduced. Hence it was assumed that FBE alleviates AD-like skin lesions in NC/Nga mice, probably by modulating the cytokine production involved in chronic inflammation, such as IFN-gamma or IL-17.

An allergic dermatitis reaction may develop after systemic exposure to a hapten that reaches the skin through haematogenous transport. This condition can be observed with and without previous cutaneous sensitization to the hapten but has traditionally been described following topical exposure. A heterogeneous clinical picture, in combination with limited insight to its pathomechanisms, makes such systemic reactions an area in need of further study. This article summarizes knowledge about systemic dermatitis elicited by drugs, with a special emphasis on possible pathomechanisms. A list of putative pathomechanisms is offered for future research. Literature was examined using PubMed-MEDLINE, EMBASE, Biosis, and Science Citation Index. Based on the literature, it is likely that humoral type 3, delayed-type hypersensitivity, and drug-driven (i.e. p-i concept) reactions are involved. As commonly used terms may be misleading because skin contact is not a prerequisite, we suggest that the term 'systemic allergic dermatitis' should be used in the future.

Purpose of Review: The review summarizes the recent investigations focused on T regulatory cells in hapten diseases., Recent Findings: Multiple mechanisms ensure tolerance to small chemicals penetrating the skin. Among these, specific T regulatory cells play a major role in controlling harmful immune responses to environmental antigens. Most of the T regulatory cells involved in this process belongs to the CD4 subset and suppress hapten-specific immune response through the release of IL-10 and through direct interaction with effector T cells, blocking their function., Summary: Methods for in-vitro and in-vivo expansion of specific T regulatory cells may represent an innovative approach for the cure of contact hypersensitivity.

In recent years, there has emerged academic tendency towards the neurogenic mechanism of ulcerative colitis (UC). As one of the supports to the hypothesis of UC being a neurogenic inflammation, we have built a colitis model by intrathecal (ith) injection of a haptten 2,4-dinitrochlorobenzene (DNCB) to DNCB-sensitized rats. In order to explore further the neuroimmunal mechanism of this colitis model, we here focused on a pro-inflammatory cytokine, migration inhibitory factor (MIF), to observe its expression in rat colon nervous tissue and spinal cord in the colitis induced by ith injection of DNCB. At the same time we also observed the effect of MIF antibody pretreatment on the disease active index (DAI) score and the colon pathology by HE staining in the colitis rats. The results obtained showed that the immunofluorescence intensity of double staining of MIF protein in colon nervous tissue and spinal cord was increased in 0.8% and 1.6% DNCB-induced colitis groups than that in the control (60% ethanol) group. Both the colon pathology and the DAI score were significantly reduced by MIF antibody ith pretreatment. Ith injection of 0.8% DNCB after MIF antibody (1:10, 1:5) pretreatment could only induce lower DAI score (P<0.01 as compared, respectively, to the IgG pretreatment group). The colon pathological changes in ith 0.8% DNCB rats were mild, even little after MIF antibody (1:10, 1:5) pretreatment. These results suggest that MIF in spinal cord and enteric nervous system is possibly involved in the rat colitis induced by ith injection of DNCB, which reflects a neuroimmunal mechanism underlying this kind of colitis. MIF is possibly one of the important neurochemical factors in this experimental colitis, even in the UC.

The rubber accelerator, 2-mercaptobenzothiazole (MBT), is known to cause allergic contact dermatitis (ACD), but the mechanism is unknown. The role of the thiol group in MBT's allergenicity was investigated in the present study. Guinea pigs were sensitized to MBT using a modified guinea pig maximization test (GPMT) and reactivity was assessed toward 2-mercaptobenzothiazole disulfide (MBTS), 2-hydroxybenzothiazole (HBT; thiol-substituted), 2-(methylthio)benzothiazole (MTBT; thiol-blocked), and benzothiazole (BT; thiol-lacking). MBT and MBTS, but not BT, HBT, or MTBT, elicited ACD in MBT-sensitized animals, demonstrating that the thiol group is critical to MBT's allergenicity. In addition, both MBT and MBTS were shown to inhibit both glutathione reductase and thioredoxin reductase, and thus contribute to the stability of MBT-protein mixed disulfides. It is concluded that the probable haptenation mechanism of MBT is through initial oxidation to MBTS with subsequent reduction to form mixed disulfides with proteins.

Drug-induced thrombocytopenia (DIT) is a relatively common clinical disorder. It is imperative to provide rapid identification and removal of the offending agent before clinically significant bleeding or, in the case of heparin, thrombosis occurs. DIT can be distinguished from idiopathic thrombocytopenic purpura, a bleeding disorder caused by thrombocytopenia not associated with a systemic disease, based on the history of drug ingestion or injection and laboratory findings. DIT disorders can be a consequence of decreased platelet production (bone marrow suppression) or accelerated platelet destruction (especially immune-mediated destruction).

Background: Three cases of drug-induced liver injury (DILI) have been reported after desflurane anesthesia. However, no previous reports have detected serum autoantibodies such as that reported with DILI from halothane or isoflurane., Methods and Results: We describe the first documentation of cytochrome P450 2E1 IgG4 autoantibodies, as well as 58 kDa endoplasmic reticulum protein and trifluoroacetyl chloride hapten-specific IgG4 antibodies, in a patient who developed DILI after desflurane anesthesia., Conclusions: These findings suggest that allergic and autoimmune mechanisms have critical roles in the development of desflurane DILI.

Generalized urticaria is an adverse and serious side effect of diphencyprone. We report a case in order to advise of the possibility of associated type I hypersensitivity reaction (urticaria), which could progress to a more severe or life-threatening adverse reaction.