Contact allergy to topical corticosteroids.

Topical corticosteroids are commonly used to treat inflammatory skin conditions due to their anti-inflammatory properties. However, patients with long-lasting, non-responsive eczema have to be evaluated for a complicating contact allergy to the topical product. Clinical management of allergic contact dermatitis to corticosteroids can be challenging. The preventive measures should be tailored according to the sensitization patterns and supported by currently available classification systems to avoid cross-reactivity, as argued in this review.

Endothelial Protein C Receptor and 3K3A-Activated Protein C Protect Mice from Allergic Contact Dermatitis in a Contact Hypersensitivity Model.

Endothelial protein C receptor (EPCR) is a receptor for the natural anti-coagulant activated protein C (aPC). It mediates the anti-inflammatory and barrier-protective functions of aPC through the cleavage of protease-activated receptor (PAR)1/2. Allergic contact dermatitis is a common skin disease characterized by inflammation and defective skin barrier. This study investigated the effect of EPCR and 3K3A-aPC on allergic contact dermatitis using a contact hypersensitivity (CHS) model. CHS was induced using 1-Fluoro-2,4-dinitrobenzene in EPCR-deficient (KO) and matched wild-type mice and mice treated with 3K3A-aPC, a mutant form of aPC with diminished anti-coagulant activity. Changes in clinical and histological features, cytokines, and immune cells were examined. EPCRKO mice displayed more severe CHS, with increased immune cell infiltration in the skin and higher levels of inflammatory cytokines and IgE than wild-type mice. EPCR, aPC, and PAR1/2 were expressed by the skin epidermis, with EPCR presenting almost exclusively in the basal layer. EPCRKO increased the epidermal expression of aPC and PAR1, whereas in CHS, their expression was reduced compared to wild-type mice. 3K3A-aPC reduced CHS severity in wild-type and EPCRKO mice by suppressing immune cell infiltration/activation and inflammatory cytokines. In summary, EPCRKO exacerbated CHS, whereas 3K3A-aPC could reduce the severity of CHS in both EPCRKO and wild-type mice.

The management of Chronic Hand Eczema: A retrospective patient record review.

BACKGROUND: Chronic Hand Eczema (CHE) is a heterogeneous fluctuating inflammatory disease that represents a significant burden. Effective treatment options for moderate to severe CHE are limited. OBJECTIVES: To assess how patients with moderate to severe CHE are treated in clinical practice. METHODS: A retrospective, physician-led patient record review assessed the demographic, clinical and treatment characteristics of patients aged ≥18 years with CHE across seven countries. Each participating physician was requested to review records for their three most recent patients with moderate to severe CHE treated with a topical or systemic therapy. RESULTS: A total of 264 physicians, of whom 88.6% were dermatologists and 70.1% were predominantly or partly hospital-based, reviewed the records of 792 patients. Signs were present on hands only in 56.4% of patients and the mean time on current treatment was 16.7 months. Overall, 62.9% of patients received systemic therapy and almost one-quarter (23.4%) were treated with a biologic; 28.6% of patients were only treated with topical corticosteroids and/or topical calcineurin inhibitors. CONCLUSION: In patients with moderate to severe CHE, most received systemic therapy with one-quarter on biologic therapy. However, given that many of these treatments have limited evidence of efficacy in CHE, there is a need for studies specifically in patients with CHE as well as new therapeutic options.

Topical corticosteroids inhibit allergic skin inflammation but are ineffective in impeding the formation and expansion of resident memory T cells.

BACKGROUND: Tissue-resident memory T (TRM ) cells are detrimental in allergic contact dermatitis (ACD), in which they contribute to the chronicity and severity of the disease. METHODS: We assessed the impact of a standard topical corticosteroid (TCS) treatment, triamcinolone acetonide (TA), on the formation, maintenance and reactivation of epidermal TRM cells in a preclinical model of ACD to 2,4-dinitrofluorobenzene. TA 0.01% was applied at different time points of ACD response and we monitored skin inflammation and tracked CD8+ CD69+ CD103+ TRM by flow cytometry and RNA sequencing. RESULTS: The impact of TA on TRM formation depended on treatment regimen: (i) in a preventive mode, that is, in sensitized mice before challenge, TA transiently inhibited the infiltration of effector T cells and the accumulation of TRM upon hapten challenge. In contrast, (ii) in a curative mode, that is, at the peak of the ACD response, TA blocked skin inflammation but failed to prevent the formation of TRM . Finally, (iii) in a proactive mode, that is, on previous eczema lesions, TA had no effect on the survival of skin TRM , but transiently inhibited their reactivation program upon allergen reexposure. Indeed, specific TRM progressively regained proliferative functions upon TA discontinuation and expanded in the tissue, leading to exaggerated iterative responses. Interestingly, TRM re-expansion correlated with the decreased clearance of hapten moieties from the skin induced by repeated TA applications. CONCLUSIONS: Our results demonstrate that TCS successfully treat ACD inflammation, but are mostly ineffective in impeding the formation and expansion of allergen-specific TRM , which certainly restricts the induction of lasting tolerance in patients with chronic dermatitis.

Cream versus ointment: Randomized single-blinded study on the adherence to treatment with topical methylprednisolone aceponate.

BACKGROUND: Overall adherence in the treatment of chronic dermatoses is poor. Textbooks state an adherence dependence on galenics. TRIAL DESIGN: Prospective, randomized, parallel-grouped, single-blinded (investigator), monocentric clinical trial (phase IV) on the adherence to treatment of chronic mild to moderate hand eczema with topical methylprednisolone aceponate (MPA, Advantan®) in different vehicles. OBJECTIVES AND ENDPOINTS: Primary objective was the assessment of the adherence depending on vehicle type in patients with chronic hand eczema. Secondary objective was improvement after a 4-week treatment period. Primary Endpoint Adherence is defined as the percentage of patients applying at least aimed daily dose. Prescribed daily dose was defined as the planned number of applications per day (1) * surface (measured) * aimed amount per application (mg/cm2 ). Truly applicated daily dose was evaluated as individual mean amount per dose * individual mean number of applications per day. Adherence was assumed, if truly applicated daily dose is at least 75% of the prescribed daily dose and the individual mean number of applications per day is at least 0.85. Secondary Endpoint Efficacy was measured by improvement of Hand Eczema Severity Index (HECSI) and Investigator's Global Assessment (IGA) after a 4-week treatment period and in addition to Quality of Life in Hand Eczema Questionnaire (QOLHEQ) and Visual Analogue Scale (VAS) to assess pruritus. METHODS: Number of participants randomized to each group 40, 80 total. Group 1 MPA-C: Methylprednisolone aceponate 0.1% cream and barrier repair emollient (Bepanthen® Sensiderm). Group 2 MPA-FO: Methylprednisolone aceponate 0.1% fatty ointment and barrier repair emollient (Bepanthen® Sensiderm). Adherence to treatment was compared via Fisher's exact test. RESULTS: Of the patients, 48% were adherent according to our definition. There was no significant difference between MPA-C (42.1%) and MPA-FO (54.1%; p = 0.36; group difference-12.0%, 95% CI-34.3%-11.5%). Generalized-linear-model-analysis of adherence to study treatment with factors emollient use, treatment, time and treatment-time interaction showed a parallel between adherence and amount of emollient use (odds ratio 1.74, p = 0.0038; 95% CI-1.22-2.52). Improvement of hand eczema was seen according to clinical scores without remarkable differences between the groups. CONCLUSIONS: No dependence of adherence on galenics of topical treatment of chronic hand eczema could be proved. Patients who use more emollient tend to be more adherent to the topical treatment.

The efficacy of a transdermal hydrogel patch containing betamethasone dipropionate for treatment of chronic hand eczema: A single-blind, randomized and controlled trial.

BACKGROUND: Topical corticosteroids under occlusion have been used to enhance the treatment of eczema. However, no study has investigated the efficacy of a steroid-containing transdermal patch for the treatment of chronic hand eczema. METHODS: We conducted a randomized, controlled, assessor-blinded trial to determine the efficacy of a transdermal patch containing betamethasone dipropionate compared to topical betamethasone dipropionate ointment in the treatment of mild to moderate chronic hand eczema. The patients were included and assigned to receive either the transdermal patch once daily at night or the ointment twice daily for a period of 8 weeks. The outcomes were assessed using the Hand Eczema Severity Index (HECSI), Physical Global Assessment (PGA) score, self-reported compliance, level of patient satisfaction, quality of life, and side effects. RESULTS: Fifty-six patients completed this study. At 8 weeks, there was a significant reduction in the HECSI scores in both the transdermal patch and topical ointment groups compared to those measured at baseline (14.61 to 1.86, p < 0.001; 18.46 to 3.43, p < 0.001, respectively) without a statistically significant difference between the two groups. Similarly, the two groups did not show any significant difference in the PGA scores, quality of life and side effects. However, the transdermal patch group reported better compliance and a higher level of patient satisfaction than the topical ointment group. CONCLUSION: The transdermal corticosteroid patch has proven to be a safe and effective treatment, comparable to topical corticosteroids, after 8 weeks of use. Its sustained-release properties, along with once-daily use, can improve patient satisfaction and promote greater adherence to the treatment. TRIAL REGISTRATION: This study was registered with the Thai Clinical Trials Registry (www. CLINICALTRIALS: in.th) under registration number TCTR20220413003.

Mechanisms of the PD-1/PD-L1 pathway in itch: From acute itch model establishment to the role in chronic itch in mouse.

Programmed cell death receptor/ligand 1 (PD-1/PD-L1) blockade therapy for various cancers induces itch. However, few studies have evaluated the mechanism underlying PD-1/PD-L1 inhibitor-induced itch. This study aimed to establish and evaluate a mouse model of acute itch induced by PD-1/PD-L1 inhibitors and to explore the role of the PD-1/PD-L1 pathway in chronic itch. The intradermal injection of the PD-1/PD-L1 small molecule inhibitors, or anti-PD-1/PD-L1 antibodies in the nape of the neck in the mice elicited intense spontaneous scratches. The model was evaluated using pharmacological methods. The number of scratches was reduced by naloxone but not by antihistamines or the transient receptor potential (TRP) channel inhibitor. Moreover, the PD-1 receptor was detected in the spinal cord of the mouse models of chronic itch that exhibited acetone, diethyl ether, and water (AEW)-induced dry skin, imiquimod-induced psoriasis, and 1-fluoro-2,4-dinitrobenzene (DNFB)-induced allergic contact dermatitis. Intrathecal PD-L1 (1 µg, 4 times a week for 1 week) suppressed the activation of the microglia in the spinal dorsal horn to relieve the chronic itch that was elicited by imiquimod-induced psoriasis and DNFB-induced allergic contact dermatitis. Although the activation of the microglia in the spinal dorsal horn was not detected in the AEW-treated mice, intrathecal PD-L1 still reduced the number of scratches that were elicited by AEW. Our findings suggest that histamine receptor inhibitors or TRP channel inhibitors have limited effects on PD-1/PD-L1 inhibitor-induced itch and that spinal PD-1 is important for the spinal activation of the microglia, which may underlie chronic itch.

Anti-Inflammatory and Antipruritic Effects of Remote Ischaemic Postconditioning in a Mouse Model of Experimental Allergic Contact Dermatitis.

Background and Objectives: Allergic contact dermatitis is a common type IV hypersensitivity reaction characterised by redness, itching, oedema and thickening of the skin. It occurs in about 7% of the population and its incidence is increasing. It has been observed that the preconditioning of tissues by exposing them to transient ischemia increases resistance to subsequent permanent ischemia, and this phenomenon is called ischemic preconditioning. It has been shown that conditioning in one organ can also protect other organs. The protective effect of remote ischemic preconditioning is thought to be based on the induction of anti-inflammatory responses. The aim of this project was to investigate the anti-inflammatory and antipruritic effects of remote ischemic postconditioning in a mouse model of experimental allergic contact dermatitis. Methods: Experimental allergic contact dermatitis was induced with 1-fluoro-2,4-dinitrobenzene. Remote ischemic postconditioning was performed at 3 and 25 h after the challenge. Ear thickness and number of scratches 24 and 48 h after challenge, as well as cytokine levels and the infiltration of mast cells, neutrophils, CD4+ and CD8+ T lymphocytes in serum and ear tissue at 48 h were measured to determine the effect of RIPsC. Results: Remote ischemic postconditioning decreased ear thickness, one of the symptoms of allergic contact dermatitis (p < 0.0001). It had no significant effect on the number of scratches. It reduced serum IL-17 levels (p < 0.01). It alleviated local inflammation by suppressing CD8+ T lymphocyte and neutrophil infiltration. Conclusions: It was concluded that remote ischemic postconditioning may alleviate the symptoms of allergic contact dermatitis by suppressing CD8+ T lymphocyte and neutrophil infiltration and reducing IL-17 secretion.

Systemic treatments in Parthenium dermatitis: A systematic review and meta-analysis.

Parthenium dermatitis is the commonest form of plant dermatitis in India, caused by the plant Parthenium hysterophorus. Systemic immunosuppressives are commonly employed in its treatment. However, there is a relative lack of comparative head-to-head trials. This study was done to assess the relative efficacy and safety of systemic treatments in Parthenium dermatitis. We systematically reviewed all the published studies investigating the safety and efficacy of systemic treatments for Parthenium dermatitis in the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, and clinical trial registries. Treatment benefit data were tabulated based on outcome measures of scoring systems. The quality of evidence for each outcome was assessed by Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria for meta-analysis. The pooled Standardized mean difference (SMD) for case series and comparative studies based on clinical severity score (CSS) for azathioprine was 4.007 (95% CI (Confidence interval): 3.141, 4.873) and 0.746 (95% CI: 0.139, 1.352), respectively. About 88.8% (95% CI: 76.8%, 100.8%, p = 0.076) of the patients had excellent or a good response to azathioprine. Our meta-analysis shows that azathioprine has the highest level of evidence in the treatment of Parthenium dermatitis.

Dimethylglycine, a Methionine Metabolite, Participates in the Suppressive Effect of Methionine on 1-Fluoro-2,4-dinitrobenzene-Induced Dermatitis.

Allergic contact dermatitis (ACD) is a common skin disorder caused by contact with allergens. The optimal treatment for ACD is to avoid contact with allergens. However, in some cases, avoiding exposure is not possible when the allergens are unknown. Therefore, establishing treatment methods other than allergen avoidance is important. We previously reported that the continuous administration of methionine, an essential amino acid, in a mouse model of atopic dermatitis alleviated its symptoms. In the present study, we investigated the effect of methionine on a mouse model of ACD caused by 1-fluoro-2,4-dinitrobenzene (DNFB). Differences in the effect of methionine were observed in DNFB-induced ACD model mice based on the mouse strain used. This difference was attributed to the suppression of hepatic dimethylglycine (DMG) production, which is associated with the suppression of hepatic betaine-homocysteine methyltransferase (Bhmt) expression by ACD. Although we did not reveal the mechanism underlying DMG suppression, our study suggests the presence of interactions between the liver and skin in dermatitis, such as the regulation of hepatic metabolic enzyme expression in dermatitis and the alleviation of dermatitis symptoms by the hepatic metabolism status of DMG.

Pharmacological Profile of Difamilast, a Novel Selective Phosphodiesterase 4 Inhibitor, for Topical Treatment of Atopic Dermatitis.

PDE4 inhibitors are expected to be anti-inflammatory agents based on their mechanism of action, but the application of this drug class is limited by a narrow therapeutic window due to adverse effects associated with gastrointestinal function. Difamilast, a novel selective phosphodiesterase 4 (PDE4) inhibitor, demonstrated significant efficacy without adverse reactions such as nausea and diarrhea in patients with atopic dermatitis (AD) and was recently approved in Japan. In this study, we investigated the pharmacological and pharmacokinetic properties of difamilast to provide nonclinical data to help understand the clinical effects. Difamilast selectively inhibited recombinant human PDE4 activity in assays. The IC50 of difamilast against PDE4B, a PDE4 subtype that plays an important role in the inflammatory response, was 0.0112 µM, representing a 6.6-fold decrease compared with the IC50 against PDE4D (0.0738 µM), a subtype that can trigger emesis. Difamilast inhibited TNF-α production in human (IC50 = 0.0109 µM) and mouse (IC50 = 0.0035 µM) peripheral blood mononuclear cells and improved skin inflammation in a mouse model of chronic allergic contact dermatitis. These effects of difamilast on TNF-α production and dermatitis were superior to those of other topical PDE4 inhibitors: CP-80633, cipamfylline, and crisaborole. In pharmacokinetic studies using miniature pigs and rats, the concentrations of difamilast in the blood and brain after topical application were not sufficient to support pharmacological activity. This nonclinical study contributes to explain the efficacy and safety of difamilast with a sufficient therapeutic window in the clinical trials. SIGNIFICANCE STATEMENT: This is the first report on the nonclinical pharmacological profile of difamilast ointment, a novel topical PDE4 inhibitor that demonstrated utility in clinical trials in patients with atopic dermatitis. Difamilast, which has high PDE4 selectivity (especially for the PDE4B subtype), ameliorated chronic allergic contact dermatitis in mice after topical application, with a pharmacokinetic profile in animals that suggests few systemic side effects; thus, difamilast is a promising new therapeutic treatment for atopic dermatitis.

Janus Kinase Inhibitors: A Promising Therapeutic Option for Allergic Contact Dermatitis.

Janus kinase (JAK) inhibitors represent a promising class of small molecule inhibitors that treat a range of inflammatory skin diseases, such as atopic dermatitis (AD), psoriasis, and alopecia areata. Although the evidence for their use in allergic contact dermatitis (ACD) remains limited, early results from animal studies and case reports are promising. Herein, we provide an overview of JAK inhibitors and the evidence for their use in ACD.

Ozonated oil alleviates dinitrochlorobenzene-induced allergic contact dermatitis via inhibiting the FcεRI/Syk signaling pathway. / 医用臭氧油通过抑制FcεRI/Syk信号通路缓解DNCB诱导的变应性接触性皮炎（英文）.

OBJECTIVES: Ozone is widely applied to treat allergic skin diseases such as eczema, atopic dermatitis, and contact dermatitis. However, the specific mechanism remains unclear. This study aims to investigate the effects of ozonated oil on treating 2,4-dinitrochlorobenzene (DNCB)-induced allergic contact dermatitis (ACD) and the underling mechanisms. METHODS: Besides the blank control (Ctrl) group, all other mice were treated with DNCB to establish an ACD-like mouse model and were randomized into following groups: a model group, a basal oil group, an ozonated oil group, a FcεRI-overexpressed plasmid (FcεRI-OE) group, and a FcεRI empty plasmid (FcεRI-NC) group. The basal oil group and the ozonated oil group were treated with basal oil and ozonated oil, respectively. The FcεRI-OE group and the FcεRI-NC group were intradermally injected 25 µg FcεRI overexpression plasmid and 25 µg FcεRI empty plasmid when treating with ozonated oil, respectively. We recorded skin lesions daily and used reflectance confocal microscope (RCM) to evaluate thickness and inflammatory changes of skin lesions. Hematoxylin-eosin (HE) staining, real-time PCR, RNA-sequencing (RNA-seq), and immunohistochemistry were performed to detct and analyze the skin lesions. RESULTS: Ozonated oil significantly alleviated DNCB-induced ACD-like dermatitis and reduced the expressions of IFN-γ, IL-17A, IL-1ß, TNF-α, and other related inflammatory factors (all P<0.05). RNA-seq analysis revealed that ozonated oil significantly inhibited the activation of the DNCB-induced FcεRI/Syk signaling pathway, confirmed by real-time PCR and immunohistochemistry (all P<0.05). Compared with the ozonated oil group and the FcεRI-NC group, the mRNA expression levels of IFN-γ, IL-17A, IL-1ß, IL-6, TNF-α, and other inflammatory genes in the FcεRI-OE group were significantly increased (all P<0.05), and the mRNA and protein expression levels of FcεRI and Syk were significantly elevated in the FcεRI-OE group as well (all P<0.05). CONCLUSIONS: Ozonated oil significantly improves ACD-like dermatitis and alleviated DNCB-induced ACD-like dermatitis via inhibiting the FcεRI/Syk signaling pathway.

Modulation of allergic contact dermatitis via gut microbiota modified by diet, vitamins, probiotics, prebiotics, and antibiotics.

Allergic contact dermatitis is one of the most common recorded occupational diseases. There are many different substances that the skin comes into contact with on a daily basis and that can cause ACD, e.g., preservatives, surfactants, and antimicrobial agents. The development of a mouse model of ACD has provided insight into the immune mechanisms involved. Drugs used in the treatment of skin diseases have many side effects. Therefore, alternative methods of suppressing the immune response to reduce the symptoms of skin diseases are being sought. In recent years, high hopes have been placed on dietary modulation and supplementation to affect the intestinal microbial composition and promote anti-inflammatory responses. In addition, other studies have shown the crucial role of intestinal microbiota in many immune-mediated diseases. Recognition and characterization of pro- and anti-inflammatory nutrients and supplements may be crucial to support the treatment of diseases such as atopic dermatitis, acne vulgaris, psoriasis, and allergic contact dermatitis.

Melittin-Carrying Nanoparticle Suppress T Cell-Driven Immunity in a Murine Allergic Dermatitis Model.

Allergic contact dermatitis (ACD) and atopic dermatitis (AD) are the most common human skin disorders. Although corticosteroids have been widely used to treat ACD and AD, the side effects of corticosteroids encourage researchers to explore new immunoregulatory treatments. Here, an immunomodulatory approach based on lipid nanoparticles carrying α-helical configurational melittin (α-melittin-NP) is developed to overcome T cell-mediated inflammatory reactions in an oxazolone (OXA)-induced contact hypersensitivity mouse model and OXA-induced AD-like mouse model. Intradermal injection of low-dose α-melittin-NPs prevents the skin damage caused by melittin administration alone and efficiently targeted lymph nodes. Importantly, melittin and α-melittin-NPs restrain RelB activity in dendritic cells (DCs) and further suppresses dendritic cell activation and maturation in lymph nodes. Furthermore, low-dose α-melittin-NPs leads to relief of antigen recognition-induced effector T cell arrest in the dermis and inhibited allergen-specific T cell proliferation and activation. Significantly, this approach successfully controls Th1-type cytokine release in the ACD model and restricts Th2-type cytokine and IgE release in the AD-like model. Overall, intradermal delivery of low-dose α-melittin-NPs efficiently elicits immunosuppression against T cell-mediated immune reactions, providing a promising therapeutic strategy for treating skin disorders not restricted to the lesion region.

Prinsepia utilis Royle leaf extract: Ameliorative effects on allergic inflammation and skin lesions in allergic contact dermatitis and polyphenolic profiling through UPLC-MS/MS coupled to chemometric analysis.

ETHNOPHARMACOLOGICAL RELEVANCE: Allergic contact dermatitis (ACD) is a common allergic inflammatory disease that is concomitant with skin swelling, redness, dry itching, and relapses. Prinsepia utilis Royle, a Chinese and Indian folk medicine, is rich in polyphenols with potential anti-inflammatory and skin-protective activities. However, the underlying mechanism of P. utilis leaf (PUL) in the treatment of ACD and its functional basis remains unclear. AIM OF THE STUDY: This study is aimed to explore and reveal the active substances and mechanism of PUL against ACD. MATERIALS AND METHODS: Hyaluronidase inhibitory assay and fluorescein isothiocyanate (FITC)-induced ACD mouse model were performed to assess the antiallergic effects of PUL in vitro and in vivo. Different solvents were applied to obtain multiple PUL extracts. The extracts were further tested for total phenolic content (TPC) and total flavonoid content (TFC) by using spectrophotometric assays. Polyphenolic profiles were analyzed by using ultrahigh-performance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC-QTOF-MS/MS), and a simultaneous quantification method was established using UPLC-QTrap-MS/MS through multiple reaction monitoring (MRM) and applied to analyze the pharmacokinetics of the multiple major polyphenols of PUL in mice. RESULTS: The water extract of PUL with the highest TPC/TFC exhibited the strongest antihyaluronidase effect (IC50 = 231.93 µg/mL). In vivo assays indicated that the oral administration of PUL water extract dose-dependently attenuated ACD-like symptoms by decreased interleukin (IL)-4, IL-5, IL-13, IL-33, thymic stromal lymphopoietin, and IgE production, suppressed eosinophil and basophil secretion, and increasing the expression of tight junction (TJ) proteins (claudin-1 [CLDN-1] and occludin). Concomitantly, UPLC-QTOF-MS/MS analysis enabled the identification of 60 polyphenols and the pharmacokinetic parameters of seven quantified constituents of PUL were characterized. Four compounds, trans-p-coumaric acid 4-O-ß-D-glucopyranoside (11), vicenin-2 (21), isoschaftoside (31), and kaempferol 3-O-(2″,6″-di-O-α-L-rhamnopyransoyl)-ß-D-glucopyranoside (38) which displayed satisfactory pharmacokinetic features, were considered as potential effective substances in PUL. CONCLUSIONS: PUL water extract ameliorated the allergic inflammation of ACD by repairing the epithelial barrier and alleviating Th2-type allergic inflammation. The anti-allergic effect of PUL is closely related to its phenolic substances, and compounds 11, 21, 31, and 38 were the active substances of PUL. It revealed that P. utilis could be developed as a new source of antiallergic agents for ACD therapy.

TRPA1 is involved in the inhibitory effect of Ke-teng-zi on allergic contact dermatitis via MAPK and JAK/STAT3 signaling pathways.

ETHNOPHARMACOLOGICAL RELEVANCE: The seeds of Entada phaseoloides (Linn.) Merr. commonly named "Ke-teng-zi" is a traditional Chinese folk medicine and reported to treat dermatitis, spasm, and headache. However, the exact effect and the mechanism of Ke-teng-zi on the treatment of dermatitis is unclear. AIM OF THE STUDY: To elucidate the antipruritic effect and molecular mechanisms of Ke-teng-zi on the treatment of allergic contact dermatitis (ACD). MATERIALS AND METHODS: The main components of the n-butanol fraction of 70% ethanol extract from Ke-teng-zi (abbreviated as KB) were analyzed by HPLC. The chloroquine (CQ)-induced acute itch and squaraine dibutyl ester (SADBE)-induced ACD chronic itch in mice was established, and the TNF-α/IFN-γ stimulated Human keratinocytes (HaCaT) were used to evaluate the antipruritic and anti-inflammatory effects of KB. Behavioral tests, lesion scoring, and histology were also examined. The expression levels of molecules in MAPK and JAK/STAT3 pathways, the mRNA levels of chemokines and cytokines in both the skin of ACD mice and the HaCaT cells were detected by western blot and qPCR. Furthermore, whole-cell patch-clamp recordings in TRPA1-tranfected HEK293T cells were used to elucidate the effect of KB on TRPA1 channels. TRPA1 siRNA was used to evaluate the role of TRPA1 in the anti-inflammatory effect of KB in keratinocytes. RESULTS: The main compounds in KB could bind to the active sites of TRPA1 mainly through hydrogen bond and hydrophobic bond interactions. KB could inhibit the scratching behavior in CQ-induced acute itch, and the inhibitory effect of KB was blocked by TRPA1 inhibitor HC-030031. In addition, KB significantly decreased the scratching bouts of ACD mice, reduced the skin lesion scores, mast cells degranulation, and epidermal thickening, inhibited the production of inflammatory chemokines/cytokines and CGRP, and down-regulated the levels of p-ERK1/2, p-p38, and p-STAT3, compared to the ACD mice. Moreover, continuous application of KB induced the desensitization of TRPA1 channels. Also, KB inhibited the expression of p-ERK1/2, p-p38, and p-STAT3, and down-regulated the expression of inflammatory chemokines and cytokines in vitro, which were reversed by the TRPA1 siRNA. CONCLUSIONS: KB alleviated the pruritus and skin inflammation in ACD mice through TRPA1 channels desensitization and down-regulation of intracellular MAPK and JAK/STAT3 signaling pathways. Our results suggested that Ke-teng-zi is a potential drug for the treatment of inflammatory skin diseases such as ACD.