Association between TNFA-308 G/A polymorphism and sensitization to para-phenylenediamine: a case-control study

Toxicity of para-phenylenediamine (PPD;1, 4 diaminobenzene) on isolated human lymphocytes: The key role of intracellular calcium enhancement in PPD-induced apoptosis

Para-phenylenediamine (PPD) is a derivative of benzene used as an ingredient in dyes, a photographic developing agent, and a component of engineered polymers. The carcinogenicity of PPD, which has been documented in several studies, may be related to its toxic effects on different compartments of the immune system. The main goal of this research was to evaluate the mechanism of the toxicity of PPD on human lymphocytes by exploiting the accelerated cytotoxicity mechanism screening (ACMS) technique. Lymphocytes were isolated from the blood of healthy persons using a Ficoll-Paque PLUS standard method. Assessment of cell viability was carried out 12 h following treatment of human lymphocytes with 0.25-1 mM PPD. For determination of cellular parameters, isolated human lymphocytes were incubated with 1/2 the IC50 (0.4 mM), the IC50 (0.8 mM), and twice the IC50 (1.6 mM) for 2, 4, and 6 h. Half maximal inhibitory concentration (IC50) is the concentration that reduces cell viability approximately 50% following treatment. The results of this study demonstrated that PPD-associated apoptosis in human lymphocytes was mainly through the enhancement of intracellular calcium, oxidative stress, and following adverse effect on lymphocyte organelles (like mitochondria and lysosomes). Lipid peroxidation, activation of caspase-3, and stimulation of cytokines (IL₂, interferon-gamma (IFN-γ), and TNF-alpha) production were also observed in PPD-treated lymphocytes. Considering the results of this study, we can suggest an association between PPD carcinogenicity and its toxic effects on different compartments of the immune system.

Genetic variants affecting chemical mediated skin immunotoxicity

The skin is an immune-competent organ and this function may be impaired by exposure to chemicals, which may ultimately result in immune-mediated dermal disorders. Interindividual variability to chemical-induced skin immune reactions is associated with intrinsic individual characteristics and their genomes. In the last 30-40 years, several genes influencing susceptibility to skin immune reactions were identified. The aim of this review is to provide information regarding common genetic variations affecting skin immunotoxicity. The polymorphisms selected for this review are related to xenobiotic-metabolizing enzymes (CYPA1 and CYPB1 genes), antioxidant defense (GSTM1, GSTT1, and GSTP1 genes), aryl hydrocarbon receptor signaling pathway (AHR and ARNT genes), skin barrier function transepidermal water loss (FLG, CASP14, and SPINK5 genes), inflammation (TNF, IL10, IL6, IL18, IL31, and TSLP genes), major histocompatibility complex (MHC) and neuroendocrine system peptides (CALCA, TRPV1, ACE genes). These genes present variants associated with skin immune responses and diseases, as well as variants associated with protecting skin immune homeostasis following chemical exposure. The molecular and association studies focusing on these genetic variants may elucidate their functional consequences and contribution in the susceptibility to skin immunotoxicity. Providing information on how genetic variations affect the skin immune system may reduce uncertainties in estimating chemical hazards/risks for human health in the future.

[Extended understanding of pathogenesis and treatment of contact allergy]

BACKGROUND

While the pathogenesis of contact allergy in recent years has increasingly focused on the mechanisms of the innate immune response, valid therapeutic options are still lacking.

AIMS

This article intends to shed light on the background of contact allergy development as well as possible risk factors and to highlight potential new therapeutic options.

MATERIALS AND METHODS

Allergic contact dermatitis (ACD) as well as the sensitization and trigger phase, potential risk factors as well as the therapy options including (current) PubMed-listed literature are described.

RESULTS

Inflammation plays a central role in ACD. The innate immune system responds to contact allergens as well as to infection. Elucidation of the mechanisms will enable a targeted therapeutic intervention in the future.

CONCLUSION

Although there is still a need for research, many parts of the contact allergy pathogenesis are now better understood. In particular, the essential role of the innate immune response not only for the sensitization but also for the elicitation phase seems to be established. Implementation of today's knowledge into new therapeutic approaches and their application testing remains important and exciting.

Allergic Contact Dermatitis Due to Paraphenylenediamine: An Update

Paraphenylenediamine (PPD) is an amine that is mainly used as an ingredient in hair dyes and henna tattoos. The incidence of allergic contact dermatitis to PPD is increasing, particularly in younger patients. In this article, we review the main sources of PPD and the substances with which it can interact and present a practical algorithm for diagnosing and treating suspected cases of PPD allergy.

Pathomechanisms of Contact Sensitization

Contact sensitization is the initial process involved in the development of an allergic reaction to xenobiotic environmental substances. Here, we briefly describe the differences between irritant and allergic contact dermatitis. Then, we highlight the essential steps involved in the development of an ACD reaction, i.e., the protein binding of haptens, genetic factors influencing the penetration of sensitizers into the skin, the different mechanisms driving the initial development of an inflammatory cytokine micromilieu enabling the full maturation of dendritic cells, the role of pre- and pro-haptens, antigen presentation and T cell activation via MHC and CD1 molecules, dendritic cell (DC) migration, and potential LC contribution as well as the different T cell subsets involved in ACD. In addition, we discuss the latest publications regarding factors that might influence the sensitizing potential such as repeated sensitizer application, penetration enhancers, humidity of the skin, microbiota, Tregs, and phthalates. Last but not least, we briefly touch upon novel targets for drug development that might serve as treatment options for ACD.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Allergic contact dermatitis to para-phenylenediamine

Exposure to hair dye is the most frequent route of sensitisation to para-phenylenediamine (PPD), a common contact allergen. International studies have examined the profile of PPD, but Australian-sourced information is lacking. Patients are often dissatisfied with advice to stop dyeing their hair. This study examines patients' characteristics, patch test results and outcomes of PPD allergy from a single Australian centre, through a retrospective analysis of patch test data from 2006 to 2013 at the Liverpool Hospital Dermatology Department. It reviews the science of hair dye allergy, examines alternative hair dyes and investigates strategies for hair dyeing. Of 584 patients, 11 were allergic to PPD. Our PPD allergy prevalence rate of 2% is at the lower end of international reported rates. About half these patients also react to para-toluenediamine (PTD). Affected patients experience a significant lifestyle disturbance. In all, 78% tried alternative hair dyes after the patch test diagnosis and more than half continued to dye their hair. Alternative non-PPD hair dyes are available but the marketplace can be confusing. Although some patients are able to tolerate alternative hair dyes, caution is needed as the risk of developing an allergy to other hair dye ingredients, especially PTD, is high.

Occupational and non-occupational allergic contact dermatitis: a follow-up study

BACKGROUND/AIMS

The aim of this study was to obtain insight into the clinical course and prognosis of allergic contact dermatitis (ACD), including potential effects of genetic and environmental factors.

METHODS

Eighty-two patients with previously defined ACD acquired occupationally (OACD) or non-occupationally (NOACD) were patch retested and evaluated for the presence of persistent eczema, atopy and filaggrin mutations.

RESULTS

The crude risk for the persistence of a positive patch test (PT) reaction was 6.3 times higher (95% CI 3.63-11.0) for PT reactions assessed as '+++' compared to '++' reactions at the first PT. Among the categories of OACD, NOACD, age, gender, atopy, and the number of positive PT reactions at the first and second PT, only OACD (OR 10.0, 95% CI 1.95-51.2) and number of positive PT reactions at retesting (OR 3.85, 95% CI 1.57-9.44) were found to be predictors of persistent eczema.

CONCLUSIONS

Occupationally acquired contact allergy was emphasized as the most important factor in predicting poor prognosis of ACD.

[Genetics of contact allergy]

The genetics of contact allergy (CA) is still only partly understood, despite decades of research. This might be due to inadequately defined phenotypes used in the past. Therefore we suggested studying an extreme phenotype, namely, polysensitization (sensitization to 3 or more unrelated allergens). Another approach to unravel the genetics of CA has been the study of candidate genes. In this review, we summarize studies on the associations between genetic variation (e.g. SNPs) in certain candidate genes and CA. The following polymorphisms and mutations were studied: (1) filaggrin, (2) N-acetyltransferase (NAT1 and 2), (3) glutathione-S-transferase (GST M and T), (4) manganese superoxide dismutase, (5) angiotensin-converting enzyme (ACE), (6) tumor necrosis factor (TNF), and (7) interleukin-16 (IL16). The polymorphisms of NAT1/2, GST M/T, ACE, TNF, and IL16 were shown to be associated with an increased risk of CA. In one of our studies, the increased risk conferred by the TNF and IL16 polymorphisms was confined to polysensitized individuals. Other relevant candidate genes may be identified by studying diseases related to CA in terms of clinical symptoms, a more general pathology (inflammation) and possibly an overlapping genetic background, such as irritant contact dermatitis.

Genetic factors in contact allergy--review and future goals

The genetics of contact allergy are still only partly understood, despite decades of research; this might be a consequence of inadequately defined phenotypes used in the past. A recommendation is to study an extreme phenotype, namely, polysensitization (sensitization to three or more unrelated allergens). Another approach to unravel the genetics of contact allergy is the study of candidate genes. In this review, we summarize studies on the associations between genetic variation (e.g. single-nucleotide polymorphisms) in certain candidate genes and contact allergy. Polymorphisms and mutations affecting the following proteins were studied: (i) filaggrin; (ii) N-acetyltransferase (NAT) 1 and 2; (iii) glutathione-S-transferase (GST) M and T; (iv) manganese superoxide dismutase; (v) angiotensin-converting enzyme (ACE); (vi) tumour necrosis factor (TNF); and (vii) interleukin-16 (IL-16). The polymorphisms of NAT1, NAT2, GSTM, GSTT, ACE, TNF and IL-16 were shown to be associated with an increased risk of contact allergy. In one of our studies, the increased risk conferred by the TNF and IL-16 polymorphisms was confined to polysensitized individuals. Other relevant candidate genes may be identified by studying diseases related to contact allergy in terms of clinical symptoms, a more general pathology (inflammation), and possibly an overlapping genetic background, such as irritant contact dermatitis.

Individual susceptibility to occupational contact dermatitis

Occupational Contact Dermatitis (OCD) is one of the most common work-related diseases. High risk occupations are in health care, hairdressing, food sector and metal industry. OCD tends to become chronic; persistent OCD often results in impaired quality of life and loss of work ability. The purpose of this article is to review the present knowledge on the factors which determine individual susceptibility to acquire OCD. Recent discoveries regarding genes involved in the skin barrier, inflammatory response and biotransformation of xenobiotics provide more insight in the individual susceptibility for OCD. Knowledge of the factors which predispose to OCD is useful in occupational health practice for the application of preventive measures and for career guidance for apprentices and workers in high risk occupations.