Imunopatologia da dermatite de contato alérgica

Alternative Methods for Skin-Sensitization Assessment

Skin sensitization is a term used to refer to the regulatory hazard known as allergic contact dermatitis (ACD) in humans or contact hypersensitivity in rodents, an important health endpoint considered in chemical hazard and risk assessments. Information on skin sensitization potential is required in various regulatory frameworks, such as the Directive of the European Parliament and the Council on Registration, Evaluation and Authorization of Chemicals (REACH). The identification of skin-sensitizing chemicals previously required the use of animal testing, which is now being replaced by alternative methods. Alternative methods in the field of skin sensitization are based on the measurement or prediction of key events (KE), i.e., (i) the molecular triggering event, i.e., the covalent binding of electrophilic substances to nucleophilic centers in skin proteins; (ii) the activation of keratinocytes; (iii) the activation of dendritic cells; (iv) the proliferation of T cells. This review article focuses on the current state of knowledge regarding the methods corresponding to each of the key events in skin sensitization and considers the latest trends in the development and modification of these methods.

Inhibitory Effect of Sulfated Polysaccharide from Codium edule P.C. Silva Against 2,4-Dinitrofluorobenzene (DNFB)- Induced Allergic Contact Dermatitis on Female BALB/c Mice

Purpose: Sulfated polysaccharide from Codium species has been reported for its antiinflammatoryactivities. However, the effect of sulfated polysaccharide from Codium edule on allergic responses has not been studied. The study was conducted to determine the effect ofsulfated polysaccharide (F1) from C. edule on allergic contact dermatitis (ACD) induced by2,4-dinitrofluorobenzene (DNFB) in female BALB/c mice.

Methods: F1 was isolated using DEAE sepharose gel chromatography and chemically identifiedby LC-MS analyses. The effects of F1 on changes in ear thickness, allergic responses, andhistology were evaluated. The effects of F1 on the production of inflammatory cytokinesinterferon gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-ɑ) in serum were also quantifiedand compared with standard prednisolone therapy.

Results: F1 was identified as a heteropolysaccharide with β-D-galactans and β-L-arabinans units.F1 was non-toxic at 2000 mg/kg. Administration of F1 in DNFB-challenged mice significantlysuppressed the increase in ear thickness, erythema, desquamation, and proliferation ofinflammatory cells. F1 significantly decreased the production of inflammatory markers, IFN-γand TNF-α in a dose-dependent manner when compared to the untreated group (P < 0.05).

Conclusion: Results suggest that F1 from C. edule is a bioactive sulfated heteropolysaccharidewith anti-inflammatory activity and might be a valuable candidate molecule for the treatmentof allergic diseases such as ACD.

Drug-Induced Photosensitivity-From Light and Chemistry to Biological Reactions and Clinical Symptoms

Photosensitivity is one of the most common cutaneous adverse drug reactions. There are two types of drug-induced photosensitivity: photoallergy and phototoxicity. Currently, the number of photosensitization cases is constantly increasing due to excessive exposure to sunlight, the aesthetic value of a tan, and the increasing number of photosensitizing substances in food, dietary supplements, and pharmaceutical and cosmetic products. The risk of photosensitivity reactions relates to several hundred externally and systemically administered drugs, including nonsteroidal anti-inflammatory, cardiovascular, psychotropic, antimicrobial, antihyperlipidemic, and antineoplastic drugs. Photosensitivity reactions often lead to hospitalization, additional treatment, medical management, decrease in patient's comfort, and the limitations of drug usage. Mechanisms of drug-induced photosensitivity are complex and are observed at a cellular, molecular, and biochemical level. Photoexcitation and photoconversion of drugs trigger multidirectional biological reactions, including oxidative stress, inflammation, and changes in melanin synthesis. These effects contribute to the appearance of the following symptoms: erythema, swelling, blisters, exudation, peeling, burning, itching, and hyperpigmentation of the skin. This article reviews in detail the chemical and biological basis of drug-induced photosensitivity. The following factors are considered: the chemical properties, the influence of individual ranges of sunlight, the presence of melanin biopolymers, and the defense mechanisms of particular types of tested cells.

Biological responses to pediatric stainless steel crowns

A systematic review was conducted to identify the biological responses, allergic reaction, hypersensitivity, toxicity, and ion release profile associated with pediatric stainless steel crowns (SSCs) in the existing literature. A systematic search was undertaken according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. The inclusion criteria consisted of patients younger than 20 years of age with SSC placement on primary or permanent teeth and in vivo and in vitro exposure to SSCs. Outcomes measures included adverse oral/mucosal effects; removal/failure/replacement of the SSC; type of allergic reaction; nickel (Ni) or other ion levels in bodily fluids, cellular, genotoxic, cytotoxic, mutagenic or carcinogenic effects related to the SSC. After an initial search of 764 studies in the database, 17 articles were included in the analysis. Evidence of allergic reactions to SSCs in children is limited and obtained from mostly low-quality research. Some studies showed that the amount of Ni detected was less than the amount ingested in the daily diet. In contrast, other studies reported a significantly higher release of Ni occurred into the saliva in acidic environments. There is some concern about the leaching of metal ions such as Ni from SSCs in children at high risk for caries. Further long-term studies are required to investigate this phenomenon.

Assessment of patch test results carried out during ten years in a city in southern Brazil

BACKGROUND

Contact dermatitis affects up to 20% of the population. Patch testing for contact allergy may be needed to confirm the diagnosis.

OBJECTIVES

To describe and discuss the results of patch tests performed in a city in southern Brazil.

METHODS

A cross-sectional analysis was performed on all skin test results over ten years. Variables such as gender, age at the time of testing, and test results were evaluated. Triggering factors, duration of complain, and previous medications used related to the clinical history were retrieved for some patients by reviewing their medical records.

RESULTS

The sample was composed of 539 patch tests, of which 411 (76.2%) were from women. The age of the tested subjects ranged from 5 to 87 years. The prevalence of positive reactions in the patch tests was 391 (72.5%). The most prevalent positive reaction was to nickel sulfate (196; 36.4%), which had statistical significance when associated with female gender (p<0,001).

STUDY LIMITATIONS

Database obtained through secondary sources (the reports of the exams and the medical records), occurring the incomplete registration of some information.

CONCLUSIONS

Data analysis at the local level is important to define preventive policies.

Clinico-etiologic profile of hand dermatitis and patch response of patients at a tertiary hospital in Lagos, Nigeria: results of a prospective observational study

BACKGROUND

Hand dermatitis is an acute or chronic inflammation of the skin of the hands from a multifactorial cause which may be endogenous, exogenous, or a combination of both. With a wide range in severity and recurrent periods of flares, it has significant impact on the quality of life of its sufferers. A history of atopy predisposes patients to hand dermatitis, but contact dermatitis, either allergic or irritant, is the more commonly implicated factor in the etiology of hand dermatitis. Patch testing is an important tool in identifying the allergen responsible for allergic hand dermatitis, and this knowledge will contribute to improved management.

AIM AND OBJECTIVES

This study was undertaken to evaluate the clinical and etiologic profile and review the patch responses of patients who presented with hand dermatitis at a foremost tertiary skin clinic in the most populous state of the most populous country in Africa.

METHODS

A prospective, observational study in which consecutive walk-in patients who fulfilled the inclusion criteria were enrolled. Ethical clearance was obtained. Study tools included self-administered questionnaires, physical examination, and patch tests (European Hermal series), amongst others. The patch tests were carried out. Results were documented, and treatment was individualized based on clinical and investigation findings. The results were collated and analyzed with SPSS^® 17.0 edition (SPSS II).

RESULTS

Hand dermatitis was seen in 177 (13.3%) patients who presented during the study period. The mean age was 34.6 + 17.4 years. Almost two-thirds of patients (119; 67.2%) had chronic hand dermatitis, while 53 (32.8%) presented acutely. Patch responses were positive in 65 (36.7%) patients with paraphenylenediamine identified as the most frequent cause. Respondents had at least one (+) response to 20 of the 28 allergens, while there was no response to eight of the allergens in the European series.

CONCLUSION

The study reveals that hand dermatitis is present in a younger age group and a variety of subtypes coexist. Locally sourced allergens are needed to improve the yield of patch responses.

Effects of Carbopol® 934 proportion on nanoemulsion gel for topical and transdermal drug delivery: a skin permeation study

Nanoemulsions (NEs) are used as transdermal drug delivery systems for systematic therapeutic purposes. We hypothesized that the skin permeation profile of an NE could be modulated by incorporating it into a hydrogel containing differing proportions of thickening agent. The objectives of this study were as follows: 1) to determine the stability and skin irritability of NE gels (NGs) containing 1%, 2%, and 3% (w/w) Carbopol^® 934 (CP934) (termed NG1, NG2, and NG3, respectively); 2) to compare the skin permeation profiles and drug deposition patterns of the NGs; and 3) to visualize the drug delivery routes of the NGs. Terbinafine and citral were incorporated into the NGs as model drugs. Ex vivo skin permeation tests indicated that the percutaneous flux rates of terbinafine decreased in the order NE (215 μg/cm²) > NG1 (213 μg/cm²) > NG2 (123 μg/cm²) > NG3 (74.3 μg/cm²). The flux rates of citral decreased in the order NE (1,026 μg/cm²) > NG1 (1,021 μg/cm²) > NG2 (541 μg/cm²) > NG3 (353 μg/cm²). The NGs accumulated greater amounts of the drugs in the stratum corneum and less in the epidermis/dermis than did the NE (P<0.05) over a period of 12 h. Laser scanning confocal microscopy indicated that the NGs altered the main drug delivery routes from skin appendages to intercellular paths. Histological images suggested that perturbations to the skin structure, specifically the size of the epidermal intercellular spaces and the separation distance of dermal collagen bundles, could be significantly minimized by increasing the proportion of CP934. These results suggest that adjustments of the CP934 proportions can be used to modulate the skin permeation profiles of NGs for specific therapeutic purposes.

Patch-test results in children and adolescents: systematic review of a 15-year period

The number of studies on patch-test results in children and adolescents has gradually increased in recent years, thus stimulating reviews. This paper is a systematic review of a 15-year period devoted to studying the issue. Variations pertaining to the number and age groups of tested children and/or adolescents, the number of subjects with atopy/atopic dermatitis history, the quantity, type and concentrations of the tested substances, the test technique and type of data regarding clinical relevance, must all be considered in evaluating these studies, as they make it harder to formulate conclusions. The most common allergens in children were nickel, thimerosal, cobalt, fragrance, lanolin and neomycin. In adolescents, they were nickel, thimerosal, cobalt, fragrance, potassium dichromate, and Myroxylon pereirae. Knowledge of this matter aids health professionals in planning preventive programs aimed at improving children's quality of life and ensuring that their future prospects are not undermined.

Cytokine detection for the diagnosis of chromium allergy

BACKGROUND

Patch testing remains the gold standard method for the identification of the etiologic agent of allergic contact dermatitis. However, it is a subjective, time-consuming exam whose technique demands special care and which presents some contraindications, which hamper its use. In a recent study, we showed that the proliferation assay can suitably replace patch testing for the diagnosis of chromium allergy, which had been previously demonstrated only for nickel allergy. In this study, we try to refine the method by reducing the incubation period of cultures for lymphocyte proliferation assays in response to chromium.

OBJECTIVE

Develop an alternative or complementary diagnostic test for chromium allergic contact dermatitis.

METHODS

We compared the production of 9 cytokines (IFN-γ, IL-2, IL-4, IL-5, IL-10, IL-12, IL-13, IL-17 and RANTES) between 18 chromium-allergic patients and 19 controls.

RESULTS

Chromium increased the production of IFN-y, IL-5, IL-2 and IL-13 in allergic patients, but only IL-2 and especially IL-13 helped discriminate allergic patients from controls. The sensitivity, specificity and accuracy found with IL-13 were about 80%.

CONCLUSIONS

IL-13 and IL-2 detection may be used to diagnose chromium allergy in 2-day cultures. However, in general, the 6-day cultures seem to be superior for this purpose.