Essential factors influencing health-related-quality of life in psoriasis.

BACKGROUND: The negative impact of psoriasis on health related quality of life (HRQoL) has been well documented. An unanswered question is the relative contribution of different manifestations of psoriasis (skin, joint, nail involvement) to HRQoL. AIM: To assess the relative contribution of the different symptom domains on HRQoL in psoriasis. METHODS: 165 psoriasis patients (41.2 % with psoriasis arthritis (PsA)) were enrolled in a single-center cohort-study. For the assessment of HRQoL, patients completed EuroQoL (EQ-5D), the Short Form 36-item Health Survey (SF-36), the Health Assessment Questionaire (HAQ), and Dermatological Life Quality Index (DLQI) questionnaires. Multiple regression analysis was applied to determine the contribution of the measured parameters to the EuroQoL score (used as a reference measure for overall HRQoL). RESULTS: Psoriasis arthritis (PsA) patients showed a higher impairment in all HRQoL measures than the patients without PsA. PASI, number of affected joints (PsA-score), DLQI and HAQ were significant predictors of HRQoL (R2=0.57). HAQ was the dominant contributor to HRQoL, both in patients with PsA and without PsA (partial eta 0.23 and 0.28, respectively). Final model with improved R2 (0.61) was obtained by backward regression analysis, and included 6 parameters: PASI, PsA-score, and three questions from HAQ and one question from DLQI questionnaire. CONCLUSION: Musculoskeletal symptoms are an essential component of HRQoL in psoriasis, even in patients without active PsA. A model consisting of PASI, PsA-score, and 4 questions derived from DLQI and HAQ seems to reflect total HRQoL impairment in psoriasis. This finding may further optimize drug therapy in psoriasis.

The acyl-CoA binding protein is required for normal epidermal barrier function in mice.

The acyl-CoA binding protein (ACBP) is a 10 kDa intracellular protein expressed in all eukaryotic species. Mice with targeted disruption of Acbp (ACBP(-/-) mice) are viable and fertile but present a visible skin and fur phenotype characterized by greasy fur and development of alopecia and scaling with age. Morphology and development of skin and appendages are normal in ACBP(-/-) mice; however, the stratum corneum display altered biophysical properties with reduced proton activity and decreased water content. Mass spectrometry analyses of lipids from epidermis and stratum corneum of ACBP(+/+) and ACBP(-/-) mice showed very similar composition, except for a significant and specific decrease in the very long chain free fatty acids (VLC-FFA) in stratum corneum of ACBP(-/-) mice. This finding indicates that ACBP is critically involved in the processes that lead to production of stratum corneum VLC-FFAs via complex phospholipids in the lamellar bodies. Importantly, we show that ACBP(-/-) mice display a ∼50% increased transepidermal water loss compared with ACBP(+/+) mice. Furthermore, skin and fur sebum monoalkyl diacylglycerol (MADAG) levels are significantly increased, suggesting that ACBP limits MADAG synthesis in sebaceous glands. In summary, our study shows that ACBP is required for production of VLC-FFA for stratum corneum and for maintaining normal epidermal barrier function.

A growth curve model with fractional polynomials for analysing incomplete time-course data in microarray gene expression studies.

Identifying the various gene expression response patterns is a challenging issue in expression microarray time-course experiments. Due to heterogeneity in the regulatory reaction among thousands of genes tested, it is impossible to manually characterize a parametric form for each of the time-course pattern in a gene by gene manner. We introduce a growth curve model with fractional polynomials to automatically capture the various time-dependent expression patterns and meanwhile efficiently handle missing values due to incomplete observations. For each gene, our procedure compares the performances among fractional polynomial models with power terms from a set of fixed values that offer a wide range of curve shapes and suggests a best fitting model. After a limited simulation study, the model has been applied to our human in vivo irritated epidermis data with missing observations to investigate time-dependent transcriptional responses to a chemical irritant. Our method was able to identify the various nonlinear time-course expression trajectories. The integration of growth curves with fractional polynomials provides a flexible way to model different time-course patterns together with model selection and significant gene identification strategies that can be applied in microarray-based time-course gene expression experiments with missing observations.

Genome-wide expression analysis of human in vivo irritated epidermis: differential profiles induced by sodium lauryl sulfate and nonanoic acid.

The pathogenesis of irritant contact dermatitis (ICD) is poorly understood, and genes participating in the epidermal response to chemical irritants are only partly known. It is commonly accepted that different irritants have different mechanisms of action in the development of ICD. To define the differential molecular events induced in the epidermis by different irritants, we collected sequential biopsies ((1/2), 4, and 24 hours after a single exposure and at day 11 after repeated exposure) from human volunteers exposed to either sodium lauryl sulfate (SLS) or nonanoic acid (NON). Gene expression analysis using high-density oligonucleotide microarrays (representing 47,000 transcripts) revealed essentially different pathway responses (1/2)hours after exposure: NON transiently induced the IL-6 pathway as well as a number of mitogen-activated signaling cascades including extracellular signal-regulated kinase and growth factor receptor signaling, whereas SLS transiently downregulated cellular energy metabolism pathways. Differential expression of the cyclooxygenase-2 and matrix metalloproteinase 3 transcripts was confirmed immunohistochemically. After cumulative exposure, 883 genes were differentially expressed, whereas we identified 23 suggested common biomarkers for ICD. In conclusion, we bring new insights into two hitherto less well-elucidated phases of skin irritancy: the very initial as well as the late phase after single and cumulative mild exposures, respectively.

Extraction of high-quality epidermal RNA after ammonium thiocyanate-induced dermo-epidermal separation of 4 mm human skin biopsies.

To obtain a separation of the epidermal and dermal compartments to examine compartment specific biological mechanisms in the skin, we incubated 4 mm human skin punch biopsies in ammonium thiocyanate. We wanted to test (i) the histological quality of the dermo-epidermal separation obtained by different incubation times; (ii) the amount and quality of extractable epidermal RNA and (iii) its impact on sample RNA expression profiles assessed by large-scale gene expression microarray analysis in both normal and inflamed skin. At 30-min incubation, the split between dermis and epidermis was not always histologically well-defined (i.e. occurred partly intra-epidermally), but also varied between subjects. Consequently, curettage along the dermal surface of the biopsy was added to the procedure. This modified method resulted in an almost perfect separation of the epidermal and dermal compartments, and satisfactory amounts of high-quality RNA were obtained. Hybridization to Affymetrix HG_U133A 2.0 GeneChips showed that ammonium thiocyanate incubation had a minute effect on gene expression resulting in only one significantly downregulated gene (cystatin E/M). We conclude that epidermis can be reproducibly and almost completely separated from the dermis of 4 mm skin biopsies by 30 min incubation in 3.8% ammonium thiocyanate combined with curettage of the dermal surface, producing high-quality RNA suitable for transcriptional analysis. Our refined method of dermo-epidermal separation will undoubtedly prove valuable in the many different settings, where the epidermal and dermal compartments need to be evaluated separately.