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Background: It is unclear whether patients with atopic dermatitis (AD) have an altered prevalence or risk for contact sensitization. Increased exposure to chemicals in topical products together with impaired skin barrier function suggest a higher risk, whereas the immune profile suggests a lower risk.Objective: To perform a systematic review and meta-analysis of the association between AD and contact sensitization.Methods: The PubMed/Medline, Embase, and Cochrane databases were searched for articles that reported on contact sensitization in individuals with and without AD.Results: The literature search yielded 10,083 citations; 417 were selected based on title and abstract screening and 74 met inclusion criteria. In a pooled analysis, no significant difference in contact sensitization between AD and controls was evident (random effects model odds ratio [OR] = 0.891; 95% confidence interval [CI] = 0.771-1.03). There was a positive correlation in studies that compared AD patients with individuals from the general population (OR 1.50, 95% CI 1.23-1.93) but an inverse association when comparing with referred populations (OR 0.753, 95% CI 0.63-0.90).Limitations: Included studies used different tools to diagnose AD and did not always provide information on current or past disease. Patch test allergens varied between studies.Conclusion: No overall relationship between AD and contact sensitization was found. We recommend that clinicians consider patch testing AD patients when allergic contact dermatitis is suspected. [ABSTRACT FROM AUTHOR]

p -Phenylenediamine (PPD) is a strong contact allergen used in hair dye that is known to cause allergic contact dermatitis (ACD). Both private and occupational exposure to PPD is frequent, but the effect of PPD exposure in nonallergic occupationally exposed subjects is unknown. We sought to investigate the effects of PPD exposure on the skin of occupationally exposed subjects with and without clinical symptoms. Skin biopsy specimens were collected from 4 patients with mild and 5 patients with severe PPD-related ACD and 7 hairdressers without contact dermatitis on day 4 after patch testing with 1% PPD in petrolatum. RNA sequencing and transcriptomics analyses were performed and confirmed by using quantitative RT-PCR. Protein expression was analyzed in skin from 4 hairdressers and 1 patient with ACD by using immunofluorescence staining. Reconstructed human epidermis was used to test the effects of PPD in vitro. RNA sequencing demonstrated downregulation of tight junction and stratum corneum proteins in the skin of patients with severe ACD after PPD exposure. Claudin-1 (CLDN-1), CLDN8 , CLDN11 , CXADR-like membrane protein (CLMP) , occludin (OCLN) , membrane-associated guanylate kinase inverted 1 (MAGI1) , and MAGI2 mRNA expression was downregulated in patients with severe ACD. CLDN1 and CLMP expression were downregulated in nonresponding hairdressers and patients with mild ACD. Filaggrin 1 (FLG1) , FLG2 , and loricrin (LOR) expression were downregulated in patients with ACD. Confocal microscopic images showed downregulation of CLDN-1, FLG-1, and FLG-2 expression. In contrast, 3-dimensional skin cultures showed upregulation of FLG-1 in response to PPD but downregulation of FLG-2. PPD-exposed skin is associated with extensive transcriptomic changes, including downregulation of tight junction and stratum corneum proteins, even in the absence of clinical symptoms. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Nickel and cobalt allergy remain frequent in dermatitis patients. It is important to determine possible nickel and cobalt exposures at work as these may offer important information to regulators and physicians who perform patch testing. Clinical relevance of metal exposure is usually assessed by the treating physician via the medical history and by presentation of allergic contact dermatitis. Objectives: To screen unused non-powered hand-held work tools for nickel and cobalt release by using colorimetric spot tests. Materials & methods: A random selection of 200 non-powered hand-held work tools for sale in 2 retailers of home improvement and construction products were analyzed qualitatively for metal release using the colorimetric nickel and cobalt spot tests. Results: Nickel release was identified from 5% of 200 work tools using the dimethylglyoxime (DMG) test. In 8 of 10, positive results were located to the metal ring that acts like a cuff and is located at the end of the grip. The positive DMG test results were not related to specific categories of work tools. The cobalt spot test gave no positive test reactions. Conclusions: It appears that the proportion of work tools that release nickel, in amounts that may result in allergic nickel dermatitis, has decreased markedly, when results were compared with a Swedish study performed more than a decade ago. No cobalt release was detected but it should be underscored that hard-metal tools were not examined. Other sources of cobalt may explain the relatively high levels of cobalt allergy in dermatitis patients. [Copyright &y& Elsevier]

Genes involved in the inflammatory response resulting in allergic contact dermatitis (ACD) are only partly known. In this study, we introduce the use of high-density oligonucleotide arrays for gene expression profiling in human skin during the elicitation of ACD. Skin biopsies from normal and nickel-exposed skin were obtained from seven nickel-allergic patients and five nonallergic controls at four different time points during elicitation of eczema. Each gene expression profile was analyzed by hybridization to high-density oligonucleotide arrays. Cluster analysis of 74 genes found to be differentially expressed in the patients over time revealed that the patient samples may be categorized into two groups: an early time-point group (no clinical reaction) and a late time-point group (clinical reaction). Bioinformatics analyses unraveled the potential involvement of signal transducers and activator of transcription and small/mothers against decepentaplegic (SMAD) transcription factors in the late time-point gene expression patterns. Concerning specific genes, the homeostatic chemokine CCL19 was unexpectedly found to be highly expressed in cells scattered in the deep dermis of the late time-point samples. Taken together, these findings suggest hitherto unknown roles of SMAD transcription factors and of CCL19 in the elicitation phase of ACD.Journal of Investigative Dermatology (2007) 127, 2585–2595; doi:10.1038/sj.jid.5700902; published online 28 June 2007 [ABSTRACT FROM AUTHOR]

A letter to the editor is presented offering information related to the properties of skin protein filaggrin and epidermal nickel-binding.