Haptenos, proteínas y dermatitis atópica / Haptens, Proteins, and Atopic Dermatitis

La dermatitis atópica (DA) es una enfermedad inflamatoria crónica multifactorial. La dermatitis de contacto alérgica (DCA) y la dermatitis de contacto por proteínas (DCP) son patologías alérgicas que pueden ser comórbidas a la DA y ser causa de algunas de las exacerbaciones. Aunque la DCA tiene una prevalencia similar en pacientes atópicos que en la población general, debemos considerarla una comorbilidad frecuente en la DA por la disrupción de la barrera cutánea. Por ello, se recomienda la realización de pruebas epicutáneas a los pacientes atópicos. Dupilumab podría ser útil para el tratamiento de la DCA mediada por vía Th2 y exacerbar aquellas que ocurren por vía Th1, aunque se precisan más estudios para establecer conclusiones. El mecanismo por el que la exposición a proteínas ambientales produce exacerbaciones en la DA es controvertido, pero es un fenómeno habitual en la práctica clínica diaria. Se recomienda estudio mediante prick test a pacientes con clínica sugestiva y recomendar conductas evitativas ante pacientes sintomáticos y pruebas positivas (AU)

Atopic dermatitis is a chronic inflammatory disease that is multifactorial in nature. Allergic contact dermatitis and protein contact dermatitis are allergic conditions that may occur in the context of atopic dermatitis and be the cause of exacerbations. Although the prevalence of allergic contact dermatitis is similar in atopic patients and the general population, these 2 conditions are frequently associated because atopic inflammation disrupts the skin barrier. Skin tests are therefore recommended in atopic individuals. Dupilumab could be useful for treating allergic contact dermatitis if it is mediated by type 2 helper T cells but could exacerbate inflammation if mediated by TH1 cells: further study is needed before conclusions can be drawn. Although the mechanism by which exposure to environmental proteins exacerbates atopic dermatitis remains under discussion, such exacerbations are routinely seen in clinical practice. Prick testing is recommended in symptomatic atopic dermatitis. When prick-test findings are positive, patients should be advised to avoid the culprit substances (AU)

[Translated article] Haptens, Proteins, and Atopic Dermatitis / Haptenos, proteínas y dermatitis atópica

Atopic dermatitis is a chronic inflammatory disease that is multifactorial in nature. Allergic contact dermatitis and protein contact dermatitis are allergic conditions that may occur in the context of atopic dermatitis and be the cause of exacerbations. Although the prevalence of allergic contact dermatitis is similar in atopic patients and the general population, these 2 conditions are frequently associated because atopic inflammation disrupts the skin barrier. Skin tests are therefore recommended in atopic individuals. Dupilumab could be useful for treating allergic contact dermatitis if it is mediated by type 2 helper T cells but could exacerbate inflammation if mediated by TH1 cells: further study is needed before conclusions can be drawn. Although the mechanism by which exposure to environmental proteins exacerbates atopic dermatitis remains under discussion, such exacerbations are routinely seen in clinical practice. Prick testing is recommended in symptomatic atopic dermatitis. When prick-test findings are positive, patients should be advised to avoid the culprit substances (AU)

La dermatitis atópica (DA) es una enfermedad inflamatoria crónica multifactorial. La dermatitis de contacto alérgica (DCA) y la dermatitis de contacto por proteínas (DCP) son patologías alérgicas que pueden ser comórbidas a la DA y ser causa de algunas de las exacerbaciones. Aunque la DCA tiene una prevalencia similar en pacientes atópicos que en la población general, debemos considerarla una comorbilidad frecuente en la DA por la disrupción de la barrera cutánea. Por ello, se recomienda la realización de pruebas epicutáneas a los pacientes atópicos. Dupilumab podría ser útil para el tratamiento de la DCA mediada por vía Th2 y exacerbar aquellas que ocurren por vía Th1, aunque se precisan más estudios para establecer conclusiones. El mecanismo por el que la exposición a proteínas ambientales produce exacerbaciones en la DA es controvertido, pero es un fenómeno habitual en la práctica clínica diaria. Se recomienda estudio mediante prick test a pacientes con clínica sugestiva y recomendar conductas evitativas ante pacientes sintomáticos y pruebas positivas (AU)

Haptens, Proteins, and Atopic Dermatitis. / Haptenos, proteínas y dermatitis atópica.

Atopic dermatitis is a chronic inflammatory disease that is multifactorial in nature. Allergic contact dermatitis and protein contact dermatitis are allergic conditions that may occur in the context of atopic dermatitis and be the cause of exacerbations. Although the prevalence of allergic contact dermatitis is similar in atopic patients and the general population, these 2 conditions are frequently associated because atopic inflammation disrupts the skin barrier. Skin tests are therefore recommended in atopic individuals. Dupilumab could be useful for treating allergic contact dermatitis if it is mediated by type 2 helper T cells but could exacerbate inflammation if mediated by TH1 cells: further study is needed before conclusions can be drawn. Although the mechanism by which exposure to environmental proteins exacerbates atopic dermatitis remains under discussion, such exacerbations are routinely seen in clinical practice. Prick testing is recommended in symptomatic atopic dermatitis. When prick-test findings are positive, patients should be advised to avoid the culprit substances.

Actualización de la serie estándar española de pruebas alérgicas de contacto por el Grupo Español de Investigación en Dermatitis de Contacto y Alergia Cutánea (GEIDAC) para 2016 / The Spanish standard patch test series: 2016 update by the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC)

La serie estándar española de pruebas alérgicas de contacto recomendada por el Grupo Español de Investigación en Dermatitis de Contacto (GEIDAC) ha sido actualizada para 2016. La nueva serie sustituye a la que estaba vigente desde 2012, y el Grupo la recomienda utilizar a partir de ahora como herramienta básica de la consulta de eccema de contacto. La nueva serie estándar elimina, por la falta de frecuencia de positividades relevantes, 4 haptenos: clioquinol, tiomersal, mercurio y primina, y añade 3 nuevos: metilisotiazolinona, diazolidinil urea e imidazolidinil urea. Modifica además la concentración en agua de 2 haptenos clásicos muy importantes: la mezcla metilcloroisotiazolinona/metilisotiazolinona, que pasa a 200ppm aq, y el formaldehído, que se parcheará a partir de ahora al 2% aq. La actualización de la serie estándar española es una de las funciones del GEIDAC, que vela por su adecuación a la epidemiología y la casuística de nuestro entorno

The Spanish standard patch test series, as recommended by the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC), has been updated for 2016. The new series replaces the 2012 version and contains the minimum set of allergens recommended for routine investigation of contact allergy in Spain from 2016 onwards. Four haptens —clioquinol, thimerosal, mercury, and primin— have been eliminated owing to a low frequency of relevant allergic reactions, while 3 new allergens -methylisothiazolinone, diazolidinyl urea, and imidazolidinyl urea- have been added. GEIDAC has also modified the recommended aqueous solution concentrations for the 2 classic, major haptens methylchloroisothiazolinone and methylisothiazolinone, which are now to be tested at 200ppm in aqueous solution, and formaldehyde, which is now to be tested in a 2% aqueous solution. Updating the Spanish standard series is one of the functions of GEIDAC, which is responsible for ensuring that the standard series is suited to the country's epidemiological profile and pattern of contact sensitization

Optimization of Folate-Targeted Immunotherapy for the Treatment of Experimental Arthritis.

Folate-targeted immunotherapy constitutes a powerful method for the treatment of established arthritis in multiple animal models of the disease. The therapy involves immunization of the animal against a hapten to induce anti-hapten antibodies, followed by injection with a folate-hapten conjugate to decorate the surface of folate receptor-positive (activated) macrophages with the antigenic hapten. The hapten-marked macrophages are then recognized by the anti-hapten antibodies and eliminated by immune mechanisms, leading to attenuation of disease symptoms. In the following paper, we optimize the therapy for elimination of inflammatory macrophages and suppression of rheumatoid arthritis symptoms. We also demonstrate a tight correlation between folate receptor-positive macrophage abundance in the liver and inflammation of affected joints. The results suggest that therapies that reduce folate receptor-positive macrophage populations in the body should constitute effective treatments for rheumatoid arthritis.

Impact of distinct chemical structures for the development of a methamphetamine vaccine.

(+)-Methamphetamine (METH) use and addiction has grown at alarming rates over the past two decades, while no approved pharmacotherapy exists for its treatment. Immunopharmacotherapy has the potential to offer relief through producing highly specific antibodies that prevent drug penetration across the blood-brain barrier thus decreasing reinforcement of the behavior. Current immunotherapy efforts against methamphetamine have focused on a single hapten structure, namely linker attachment at the aromatic ring of the METH molecule. Hapten design is largely responsible for immune recognition, as it affects presentation of the target antigen and thus the quality of the response. In the current paper we report the systematic generation of a series of haptens designed to target the most stable conformations of methamphetamine as determined by molecular modeling. On the basis of our previous studies with nicotine, we show that introduction of strategic molecular constraint is able to maximize immune recognition of the target structure as evidenced by higher antibody affinity. Vaccination of GIX(+) mice with six unique METH immunoconjugates resulted in high antibody titers for three particularly promising formulations (45-108 µg/mL, after the second immunization) and high affinity (82, 130, and 169 nM for MH2, MH6, and MH7 hapten-based vaccines, respectively). These findings represent a unique approach to the design of new vaccines against methamphetamine abuse.

Alopecia areata update: part II. Treatment.

UNLABELLED: Various therapeutic agents have been described for the treatment of alopecia areata (AA), but none are curative or preventive. The aim of AA treatment is to suppress the activity of the disease. The high rate of spontaneous remission and the paucity of randomized, double-blind, placebo-controlled studies make the evidence-based assessment of these therapies difficult. The second part of this two-part series on AA discusses treatment options in detail and suggests treatment plans according to specific disease presentation. It also reviews recently reported experimental treatment options and potential directions for future disease management. LEARNING OBJECTIVES: After completing this learning activity, participants should be able to compare the efficacy and safety of various treatment options, formulate a treatment plan tailored to individual patients, and recognize recently described treatments and potential therapeutic approaches.

[Bispecific antibodies: what future?]. / Anticorps bispécifiques : quel avenir ?

Monoclonal antibodies have emerged as a very successful class of therapeutic agents. In their native format, monoclonal antibodies are monospecific in that they recognize only one epitope, but their Fc domain also binds to FcfR-expressing cells. Attempts to improve the cytotoxicity of antibodies, particularly in the cancer field, have led to the design of bispecific antibodies: this can occur through various strategies, such as quadroma, thioether-linked Fab' gamma fragments or genetic engineering. Such bispecific antibodies have been developped to enhance immunotherapy, by bridging tumor cells and T cells, or radioimmunotherapy by combining bispecific antibodies and radiolabeled bivalent haptens that bind cooperatively to target cells. Multiple further applications can be envisaged such as targeting two different antigens on the same cell, or two epitopes of the same antigen. Although progresses have been slowed by technical constraints, there is little doubt that this class of novel antibodies derivatives will experience a promising development.

Strategy to prevent drug-related hypersensitivity in folate-targeted hapten immunotherapy of cancer.

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.

Modulation of benzo[a]pyrene induced immunotoxicity in mice actively immunized with a B[a]P-diphtheria toxoid conjugate.

Benzo[a]pyrene (B[a]P) is a small molecular weight carcinogen and the prototype of polycyclic aromatic hydrocarbons (PAHs). While these compounds are primarily known for their carcinogenicity, B[a]P and its metabolites are also toxic for mammalian immune cells. To develop a prophylactic immune strategy against detrimental effects of B[a]P, we have immunized mice with a B[a]P-diphtheria toxoid conjugate vaccine. We showed that high levels of antibodies against B[a]P and its metabolites modulate the redistribution of these PAHs in the blood. After immunization, increased levels of B[a]P and its metabolites were recovered in the blood. B[a]P significantly suppressed the proliferative response of both T and B cells after a sub-acute administration, an effect that was completely reversed by vaccination. In immunized mice also the immunotoxic effect of B[a]P on IFN-gamma, IL-12, TNF-alpha production and the reduced B cell activation was restored. Finally, our results showed that specific antibodies inhibited the induction of Cyp1a1 by B[a]P in lymphocytes and Cyp1b1 in the liver, enzymes that are known to convert the procarcinogen B[a]P to the ultimate DNA-adduct forming metabolite, a major risk factor of chemical carcinogenesis. Thus, we demonstrate that vaccination with a B[a]P conjugate vaccine based on a carrier protein used in licensed human vaccines reduces immunotoxicity and possibly other detrimental effects associated with B[a]P.

Folate-targeted hapten immunotherapy of adjuvant-induced arthritis: comparison of hapten potencies.

We have previously reported that disease symptoms can be greatly ameliorated in rodents with adjuvant-induced arthritis (AIA) by first immunizing the rodents against fluorescein and then treating the animals with folate-fluorescein. In this targeted hapten therapy, folate-fluorescein was shown to decorate folate receptor (FR)-expressing activated macrophages with fluorescein (an immunogenic hapten), leading to binding of antifluorescein antibodies and the consequent elimination of the activated macrophages by Fc receptor-expressing immune cells. In the current study, we compare the therapeutic potencies of a variety of FR-targeted haptens in treating the symptoms of AIA in rats. Rats were immunized with either dinitrophenyl (DNP) or trinitrophenyl (TNP) conjugated to keyhole limpet hemocyanin followed by induction of AIA with heat-inactivated Mycobacterium butyricum. Following development of arthritis, rats were treated with one of five folate-hapten conjugates (folate-DNP1, folate-DNP2, folate-DNP3, folate-FITC, or folate-TNP) at two different doses (30 nmol/kg or 200 nmol/kg) 5x/week for 25 days. Symptoms of AIA in treated rats, including paw swelling, arthritis score, splenomegaly, bone erosion, and FR(+) activated macrophage density in inflamed tissues, were quantitated over the course of therapy. Although all folate-hapten conjugates promoted a reduction in disease symptoms, folate-TNP and folate-FITC proved to be more potent than any of the 3 folate-DNP conjugates. We conclude that both folate-TNP and folate-FITC constitute promising haptens for use in FR-targeted immunotherapy of arthritis.

Low-dose radiation potentiates the therapeutic efficacy of folate receptor-targeted hapten therapy.

PURPOSE: Human cancers frequently overexpress a high-affinity cell-surface receptor for the vitamin folic acid. Highly immunogenic haptens can be targeted to folate receptor-expressing cell surfaces by administration of folate-hapten conjugates, rendering the decorated tumor cell surfaces more recognizable by the immune system. Treatment of antihapten-immunized mice with folate-hapten constructs results in elimination of moderately sized tumors by the immune system. However, when subcutaneous tumors exceed 300 mm(3) before initiation of therapy, antitumor activity is significantly decreased. In an effort to enhance the efficacy of folate-targeted hapten immunotherapy (FTHI) against large tumors, we explored the combination of targeted hapten immunotherapy with low-dose radiotherapy. METHODS AND MATERIALS: Mice bearing 300-mm(3) subcutaneous tumors were treated concurrently with FTHI (500 nmol/kg of folate conjugated to fluorescein isothiocyanate, 20,000 U/dose of interleukin 2, and 25,000 U/dose of interferon alpha) and low-dose radiotherapy (3 Gy/dose focused directly on the desired tumor mass). The efficacy of therapy was evaluated by measuring tumor volume. RESULTS: Tumor growth analyses show that radiotherapy synergizes with FTHI in antihapten-immunized mice, thereby allowing for cures of animals bearing tumors greater than 300 mm(3). More importantly, nonirradiated distal tumor masses in animals containing locally irradiated tumors also showed improved response to hapten immunotherapy, suggesting that not all tumor lesions must be identified and irradiated to benefit from the combination therapy. CONCLUSIONS: These results suggest that simultaneous treatment with FTHI and radiation therapy can enhance systemic antitumor activity in tumor-bearing mice.

Folate-targeted dinitrophenyl hapten immunotherapy: effect of linker chemistry on antitumor activity and allergic potential.

Targeting of malignancies with folate-linked therapeutics has proven to be a promising endeavor due to the preferential expression of folate receptors (FR) on human tumors. We have shown that folic acid (pteroyl-glutamate) can be used to deliver an antigenic hapten, fluorescein, to the surface of tumor cells to promote their opsonization within a fluorescein-immunized host. Here, we investigate structure-activity relationships among members of another class of folate-hapten conjugates ( EC57, EC63, EC0293, and EC0294), namely, those containing the dinitrophenyl (DNP) group as the antigenic hapten. We report that despite exhibiting similar affinities for the FR, the antitumor activity and allergic potential of these DNP conjugates varied depending on their linker chemistries and abilities to bind anti-DNP IgG/IgE antibodies. Unlike EC57 and EC63, both EC0293 and EC0294 (i) share the identical DNP bridging chemistry to that found in keyhole limpet hemocyanin (KLH)-DNP (i.e., the immunogen), (ii) efficiently recognize DNP-specific IgG, and (iii) mediate more pronounced antitumor responses. However, EC0293 and EC0294 were also found to recognize DNP-specific IgE, and they displayed a greater risk of allergy when evaluated in a passive cutaneous anaphylaxis assay. Nonetheless, upon co-stimulation with the appropriate cytokines (IL-2/IFN-alpha), the folate-targeted "haptenization" process allowed for tumor rejection and protective antitumor immunity without causing any visible allergy in immunized mice. Our data further support the concept that folate-hapten-targeted immunotherapy may offer an effective therapeutic option for treatment of FR-positive cancers, but such treatment should proceed with caution given the risk of a potential allergic reaction.

Generalized urticaria with use of diphencyprone in the treatment of warts.

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.

Positional linker effects in haptens for cocaine immunopharmacotherapy.

Cocaine use remains a serious problem, despite intensive efforts to curb abuse. Given the lack of effective pharmacotherapeutics for the treatment of cocaine addiction, research groups have targeted immunopharmacotherapy in which the drug user's immune system is trained to recognize and remove cocaine prior to entry into the central nervous system. Antibody cocaine esterases and simple binders have been procured, however, rates and/or affinities still need improvement before clinical trials are warranted. Herein, we report the synthesis and testing of two new haptens for the procurement of cocaine binding antibodies and cocaine esterase catalytic antibodies. Central in the design of these haptens was the placement of the linker functionality distal from the anticipated cocaine epitopes in an attempt to bury the hapten deep within an antibody combining site to gain possible entropic and enthalpic advantages.

Haptens as drugs: contact allergens are powerful topical immunomodulators.

For the past 40 years, dermatologists have safely used contact sensitizers such as dinitrochlorobenzene (DNCB), diphenylcyclopropenone (DPCP), and squaric acid dibutylester (SADBE) for the treatment of warts, alopecia areata, and even skin cancers. Most of these studies have utilized these powerful topical immunomodulators in acetone, a volatile solvent that precludes development of contact sensitizers as products. We have overcome these problems and stabilized these topical immunomodulators in a non-volatile, nonirritating GRAS (generally regarded as safe) vehicle. The current review article covers the traditional use of contact sensitizers for a variety of benign and malignant conditions and discusses possible mechanisms in relation to developments in modem molecular immunodermatology.

[Allergic contact dermatitis: how to re-induce tolerance?]. / Eczéma allergique de contact: comment ré-induire une tolérance?

Allergic contact dermatitis (ACD) is a skin inflammatory disease mediated by activation of CD8+ cytotoxic T cells specific for haptens in contact with the skin. CD4+ T cells behave as both regulatory and tolerogenic cells since they down-regulate the skin inflammation in patients with ACD (regulation) and prevent the development of eczema (tolerance) in normal individuals. Thus, ACD corresponds to a breakdown of immune tolerance to haptens in contact with the skin. Several regulatory CD4+ T cell subsets (Treg), especially CD4+CD25+ natural Treg cells, are involved in immunological tolerance and regulation to haptens through the production of the immunosuppressive cytokines IL-10 and TGF-beta. Ongoing strategies to re-induce immune tolerance to haptens in patients with eczema include improvement of existing methods of tolerance induction (oral tolerance, low dose tolerance, allergen-specific immunotherapy, UV-induced tolerance) as well as development of new drugs able to activate IL-10 producing Treg cells in vivo. Ongoing and future progress in this area will open up new avenues for treatment of eczema and more generally autoimmune and allergic diseases resulting from a breakdown of tolerance to autoantigens and allergens, respectively.

Alopecia areata: what to expect from current treatments.

Alopecia areata is relatively benign and often resolves on its own, although its psychosocial impact on children and young adults can be severe. Some form of treatment is usually required. Because current treatments may not show results for 3 to 6 months, reassuring the patient and the parents and informing them about the results that can be expected are an essential part of management. The choice of treatment depends on the patient's age and the extent of alopecia activity.

Recent advances in pretargeted radioimmunotherapy.

Pretargeted delivery of radionuclides is based upon bispecific immunoconjugates that bind a target tumor antigen and a small molecule carrying the active payload. This strategy is supposed to combine the advantage of antibodies to track tumor cells in vivo and of small radiolabeled molecules that clear rapidly from normal organs and minimize toxicity. Many pretargeting approaches have been proposed, but only those using the biotin/avidin recognition system and those using bispecific anti-tumor x anti-hapten antibodies have been tested in the clinic for both immunoscintigraphy and radioimmunotherapy. Their respective advantages and drawbacks, as well as hurdles in the way of an effective therapy against solid tumors, are discussed. In the light of the encouraging results obtained so far in the clinic, pretargeting remains a most promising challenge for chemistry and biotechnology.