Genetic variation in the epidermal transglutaminase genes is not associated with atopic dermatitis.

BACKGROUND: Atopic dermatitis (AD) is a common chronic inflammatory skin disorder where epidermal barrier dysfunction is a major factor in the pathogenesis. The identification of AD susceptibility genes related to barrier dysfunction is therefore of importance. The epidermal transglutaminases (TGM1, TGM3 and TGM5) encodes essential cross-linking enzymes in the epidermis. OBJECTIVE: To determine whether genetic variability in the epidermal transglutaminases contributes to AD susceptibility. METHODS: Forty-seven single nucleotide polymorphisms (SNPs) in the TGM1, TGM3 and TGM5 gene region were tested for genetic association with AD, independently and in relation to FLG genotype, using a pedigree disequilibrium test (PDT) in a Swedish material consisting of 1753 individuals from 539 families. In addition, a German case-control material, consisting of 533 AD cases and 1996 controls, was used for in silico analysis of the epidermal TGM regions. Gene expression of the TGM1, TGM3 and TGM5 gene was investigated by relative quantification with Real Time PCR (qRT-PCR). Immunohistochemical (IHC) analysis was performed to detect TG1, TG3 and TG5 protein expression in the skin of patients and healthy controls. RESULTS: PDT analysis identified a significant association between the TGM1 SNP rs941505 and AD with allergen-specific IgE in the Swedish AD family material. However, the association was not replicated in the German case-control material. No significant association was detected for analyzed SNPs in relation to FLG genotype. TG1, TG3 and TG5 protein expression was detected in AD skin and a significantly increased TGM3 mRNA expression was observed in lesional skin by qRT-PCR. CONCLUSION: Although TGM1 and TGM3 may be differentially expressed in AD skin, the results from the genetic analysis suggest that genetic variation in the epidermal transglutaminases is not an important factor in AD susceptibility.

Characterization of EGFR and ErbB2 expression in atopic dermatitis patients.

Atopic dermatitis (AD) is one of the most common chronic inflammatory skin diseases in industrialized countries. To identify candidate genes involved in the pathogenesis of AD, we previously undertook a genome-wide approach using DNA microarrays. A transcript encoding the epidermal growth factor receptor (EGFR) was found to be among the down-regulated transcripts in AD skin. Here, we further investigated the expression pattern of two EGFR family members (EGFR and ErbB2) in AD skin on a protein level. Immunohistochemical (IHC) analysis of EGFR and ErbB2 showed decreased expression of EGFR and ErbB2 proteins in AD lesional skin as compared to skin from healthy individuals. Interestingly, we found that EGFR and ErbB2 were reciprocally expressed in an in vitro model of keratinocyte proliferation and differentiation, paralleling the expression patterns found in epidermis of healthy skin. The highest levels of EGFR transcripts were found in proliferating cells, while ErbB2 was found in differentiated cells. We show that blocking EGFR activity combined with co-stimulation of the Th2-cytokine IL4 in keratinocytes leads to induction of the inflammatory chemokine CCL26/eotaxin-3 in vitro. Accordingly, increased CCL26 transcriptional levels were observed in AD lesional skin. Taken together, suppression of EGFR may contribute to the pathogenesis of AD via the regulation of inflammatory chemokines.

Elevated peripheral allergen-specific T cell response is crucial for a positive atopy patch test reaction.

BACKGROUND: Atopic eczema is a chronic inflammatory skin disease in which several subgroups of cases can be identified. Atopy patch testing (APT) reveals allergen sensitization also in atopic eczema patients devoid of detectable allergen-specific IgE, suggesting the importance of factors other than IgE in the reaction. Here we investigate the relationship between APT reactions and allergen-specific peripheral IgE and T cell reactivity in atopic eczema patients. METHODS: Adult patients with atopic eczema (n = 64) and healthy controls (n = 24) were analyzed for reactivity to Malassezia sympodialis extract by APT, measurement of specific plasma IgE and in vitro determination of the frequency of allergen-reactive peripheral blood mononuclear cells producing interleukin-4 and interleukin-5 using the ELISpot method. RESULTS: When combining the results of the APT, IgE measurements and the ELISpot analyses, reactivity to M. sympodialis was found in a majority of the atopic eczema patients (69%), whereas the healthy controls were negative throughout. T cell reactivity to M. sympodialis, manifested by production of both interleukins 4 and 5, was highly predictive for a positive APT reaction and displayed a strongly positive correlation with the APT score. In contrast, the allergen-specific IgE levels did not predict the APT outcome, and no correlation could be found between the IgE levels and the APT score. CONCLUSION: Peripheral allergen-specific T helper 2 cell-mediated reactivity appears to be required for a positive APT reaction to M. sympodialis. The diagnostic potential of measuring peripheral allergen-specific T cell responses should be considered in atopic eczema.

Global expression profiling in atopic eczema reveals reciprocal expression of inflammatory and lipid genes.

BACKGROUND: Atopic eczema (AE) is a common chronic inflammatory skin disorder. In order to dissect the genetic background several linkage and genetic association studies have been performed. Yet very little is known about specific genes involved in this complex skin disease, and the underlying molecular mechanisms are not fully understood. METHODOLOGY/FINDINGS: We used human DNA microarrays to identify a molecular picture of the programmed responses of the human genome to AE. The transcriptional program was analyzed in skin biopsy samples from lesional and patch-tested skin from AE patients sensitized to Malassezia sympodialis (M. sympodialis), and corresponding biopsies from healthy individuals. The most notable feature of the global gene-expression pattern observed in AE skin was a reciprocal expression of induced inflammatory genes and repressed lipid metabolism genes. The overall transcriptional response in M. sympodialis patch-tested AE skin was similar to the gene-expression signature identified in lesional AE skin. In the constellation of genes differentially expressed in AE skin compared to healthy control skin, we have identified several potential susceptibility genes that may play a critical role in the pathological condition of AE. Many of these genes, including genes with a role in immune responses, lipid homeostasis, and epidermal differentiation, are localized on chromosomal regions previously linked to AE. CONCLUSIONS/SIGNIFICANCE: Through genome-wide expression profiling, we were able to discover a distinct reciprocal expression pattern of induced inflammatory genes and repressed lipid metabolism genes in skin from AE patients. We found a significant enrichment of differentially expressed genes in AE with cytobands associated to the disease, and furthermore new chromosomal regions were found that could potentially guide future region-specific linkage mapping in AE. The full data set is available at http://microarray-pubs.stanford.edu/eczema.

MicroRNAs: novel regulators involved in the pathogenesis of psoriasis?

MicroRNAs are a recently discovered class of posttranscriptional regulators of gene expression with critical functions in health and disease. Psoriasis is the most prevalent chronic inflammatory skin disease in adults, with a substantial negative impact on the patients' quality of life. Here we show for the first time that psoriasis-affected skin has a specific microRNA expression profile when compared with healthy human skin or with another chronic inflammatory skin disease, atopic eczema. Among the psoriasis-specific microRNAs, we identified leukocyte-derived microRNAs and one keratinocyte-derived microRNA, miR-203. In a panel of 21 different human organs and tissues, miR-203 showed a highly skin-specific expression profile. Among the cellular constituents of the skin, it was exclusively expressed by keratinocytes. The up-regulation of miR-203 in psoriatic plaques was concurrent with the down-regulation of an evolutionary conserved target of miR-203, suppressor of cytokine signaling 3 (SOCS-3), which is involved in inflammatory responses and keratinocyte functions. Our results suggest that microRNA deregulation is involved in the pathogenesis of psoriasis and contributes to the dysfunction of the cross talk between resident and infiltrating cells. Taken together, a new layer of regulatory mechanisms is involved in the pathogenesis of chronic inflammatory skin diseases.

The prevalence of Malassezia yeasts in patients with atopic dermatitis, seborrhoeic dermatitis and healthy controls.

Cultures for Malassezia yeasts were taken from both normal-looking skin and lesional skin in 124 patients with atopic dermatitis, 16 patients with seborrhoeic dermatitis and from normal skin of 31 healthy controls. Positive Malassezia growth was found in fewer patients with atopic dermatitis (56%) than in patients with seborrhoeic dermatitis (88%) or in healthy controls (84%, p<0.01). In the patients with atopic dermatitis, fewer positive cultures were found in lesional (28%) than in non-lesional skin (44%, p<0.05), while positive cultures were found in 75% of both lesional and non-lesional skin of patients with seborrhoeic dermatitis (not significant). M. sympodialis dominated in patients with atopic dermatitis (46%) and in healthy controls (69%). In patients with seborrhoeic dermatitis both M. sympodialis and M. obtusa were cultured in 43%. A Malassezia species extract mixture would increase the possibility of detecting IgE sensitization to Malassezia in patients with atopic dermatitis.

Malassezia sympodialis stimulation differently affects gene expression in dendritic cells from atopic dermatitis patients and healthy individuals.

It is known that 28-84% of patients with atopic dermatitis exhibit IgE and/or T-cell reactivity to the opportunistic yeast Malassezia sympodialis, which can be taken up by immature monocyte-derived dendritic cells (MDDCs), resulting in MDDC maturation. The aim of this study was to investigate whether MDDCs from patients with atopic dermatitis respond differently to M. sympodialis compared to MDDCs from healthy individuals. Immature MDDCs were stimulated with M. sympodialis and the gene expression profiles were analysed with cDNA arrays containing 406 genes. Our results show that M. sympodialis differently affected MDDCs from patients with atopic dermatitis, and more so in severely ill patients, compared with healthy individuals. Six genes were more than fivefold up-regulated in MDDCs from more than one patient with atopic dermatitis, coding for CD54, CD83, IL-8, monocyte-derived chemokine (MDC), BTG1 and IL-1R antagonist. In healthy individuals this was true only for BTG1. Up-regulations of IL-8 and MDC were confirmed at the protein level. Our findings might reflect an increased trafficking and stimulatory capacity in MDDCs from the patients, which is likely to result in a stronger inflammatory response to M. sympodialis.

Elevated levels of IgG and IgG4 to Malassezia allergens in atopic eczema patients with IgE reactivity to Malassezia.

BACKGROUND: The opportunistic yeast Malassezia is considered to be one of the factors that can contribute to atopic eczema (AE). Elevated serum IgE levels, T-cell proliferation and positive skin prick test (SPT) and atopy patch test (APT) reactions to Malassezia are found among AE patients. METHODS: Sera from 127 AE patients, 14 patients with seborrheic dermatitis (SD) and 33 healthy controls were investigated for IgE and IgG4 to M. sympodialis extract and four recombinant Malassezia allergens; rMala s 1, rMala s 5, rMala s 6, and rMala s 9. In addition, IgG to the recombinant allergens was analyzed. The IgG and IgG4 levels were compared to IgE levels and in vivo reactions (SPT and APT) to Malassezia. RESULTS: AE patients with serum IgE levels >0.35 kU/l to M. sympodialis extract had significantly higher IgG4 levels to M. sympodialis extract than AE patients without detectable serum IgE to M. sympodialis extract, SD patients and healthy controls. Among the AE patients with and without detectable serum IgE to M. sympodialis extract, respectively, there were no differences in IgG4 levels between patients with positive or negative in vivo reactions to M. sympodialis extract. IgG4 to the rMala s allergens was almost exclusively found among patients with IgE to the same allergen. Within the four tested rMala s allergens, most IgG4 reactions were found to rMala s 6, an allergen with homology to cyclophilin. CONCLUSIONS: Elevated serum IgG4 to M. sympodialis extract accompanies elevated serum IgE to the extract. This is further confirmed by the association between IgG/IgG4 and IgE to recombinant Malassezia allergens.

Stevens-Johnson syndrome associated with ciprofloxacin: a review of adverse cutaneous events reported in Sweden as associated with this drug.

Stevens-Johnson syndrome is a severe mucocutaneous reaction, which can be elicited by various drugs. We present 2 cases with this syndrome associated with ciprofloxacin treatment and review the adverse cutaneous events reported as possibly related to ciprofloxacin treatment in Sweden between 1988 and 2000. Eight cases, excluding ours, of Stevens-Johnson syndrome, toxic epidermal necrolysis, and erythema multiforme were reported. This implies an annual incidence of these adverse cutaneous events of 0.045 per 100,000 treated patients (assuming an average treatment length of 10 days). One patient died, but ciprofloxacin was not considered to be the major cause of death. Together with previous data from the literature, our report supports the view that ciprofloxacin can cause severe adverse cutaneous events.