Charlotta Enerbäck

A genome-wide search for genes predisposing to familial psoriasis by using a stratification approach

Abstract. We have performed a genome scan, using markers spaced by 10xa0cM, in the search for psoriasis-susceptibility loci. The family material of 134 affected sibling pairs was ascertained on the basis of a population genetic study in which 65% of the probands had two healthy parents. Genotyping results were analyzed for non-random excessive allele-sharing between sib pairs by using GENEHUNTER ver 1.1. A stratification approach was applied to increase the homogeneity of the material by means of an operational definition of joint complaints among affected individuals. Significant linkage to the human leukocyte antigen region on chromosomexa06p in a cohort including 42 families without joint complaints (non-parametric linkage score of 2.83, P=0.002) strongly supported the validity of this operational definition as it replicated results from an earlier linkage report with similar stratification criteria. New candidate regions on chromosomesxa03 and 15 were identified. The highest non-parametric linkage values in this study, 2.96 (P=0.0017) and 2.89 (P=0.0020), were reached on chromosomexa015 in a subgroup with joint complaints and on chromosomexa03 in a subgroup without joint complaints. In addition, confirmation of previously reported loci was established on chromosomesxa04q, 6p, and 17q. This study indicates that distinct disease loci might be involved in psoriasis etiology for various phenotypes.

Age at onset and different types of psoriasis

Summary The age at onset of psoriasis has been analysed for 11,366 psoriasis patients. The age at onset for siblings of probands has been analysed for 805 probands having one affected sibling and for 1 79 probands having two affected siblings. The age at onset curve for all probands shows a dominating maximum at about puberty but also indications for two more maxima at about 30 and 50 years of age, respectively. A more relevant picture of the risk of getting psoriasis at different ages is obtained if the onset for old people having psoriasis is investigated. The three maxima come out more clearly in this case, and the puberty maximum is not so dominating. For the families with one proband and two affected siblings there is a statistically significant correlation (Plt;0·001) between the age at onset of the proband and of the siblings, and also between the siblings. The correlation coefficient is between 0·30 and 0·45. For the probands with one affected sibling, the ages at onset of the siblings mainly fall in the same range as those of the probands. These data indicate three groups of patients with respeel to age at onset. However, the overlap between the different groups is considerable. The data presented are compatible with three, possibly genetically different, variants of psoriasis vulgaris. By studying the occurrence of psoriasis among parents of the probands, the gene frequency can be estimated assuming a recessive mode of inheritance. It then turns out that the gene frequency of the group with the earliest age at onset has a gene frequency of about 0·25, the next earliest, 0·18, and the latest, 0·14.

Analysis of three suggested psoriasis susceptibility loci in a large Swedish set of families: confirmation of linkage to chromosome 6p (HLA region), and to 17q, but not to 4q.

Psoriasis is known to be a heterogeneous disease with so far three reported major psoriasis susceptibility loci on chromosome 4q, 6p and 17q. In this study we investigated three reported gene locations by nonparametric and parametric linkage analysis in a large family set consisting of 104 families (153 sib pairs) from Sweden. We could confirm linkage to chromosome 6p. A maximum heterogeneous lod score of 2.78 was reached at locus D6S276 (α = 0.60). Allelic association studies within the HLA region indicated linkage disequilibrium at locus TNFβ with a significant p value of 0.0009. Furthermore, we obtained weak evidence of linkage to the locus on chromosome 17q while no evidence of linkage could be found to the chromosome 4q region.

A Putative Role for Psoriasin in Breast Tumor Progression

Psoriasin (S100A7) was identifi;ed as a gene highly expressed in psoriatic keratinocytes and highly and more frequently expressed in ductal carcinoma in situ (DCIS) than in invasive breast carcinomas (IBC), suggesting a potential role in tumor progression. Psoriasin expression is associated with poor prognostic factors in both DCIS and IBC. Several putative functions have been proposed for psoriasin in various disease types, but none of these can fully explain its involvement in breast tumor progression. Here, we show that down-regulation of endogenous psoriasin expression via stable short hairpin RNAs in a human IBC cell line (MDA-MB-468) increases cell migration and invasion without influencing cell proliferation and survival in vitro but inhibits tumor growth in vivo. These seemingly paradoxical results are potentially explained by the dramatic up-regulation and down-regulation of matrix metalloproteinase-13 and vascular endothelial growth factor (VEGF), respectively, observed in cells with decreased psoriasin levels compared with controls. Correlating with this, high psoriasin expression in human IBC is associated with increased angiogenesis and worse clinical outcome, and psoriasin mRNA levels are coordinately regulated with VEGF and other genes related to hypoxia and mitochondrial reactive oxygen species (ROS). Based on these results, we propose that psoriasin may play a role in breast tumor progression by promoting angiogenesis and enhancing the selection for cells that overcome its anti-invasive function. This hypothesis may explain why psoriasin expression is highest in high-grade and/or estrogen receptor-negative tumors, as these are associated with increased hypoxia and ROS, a setting in which the angiogenic effects of psoriasin are most important.

High-resolution array copy number analyses for detection of deletion, gain, amplification and copy-neutral LOH in primary neuroblastoma tumors: Four cases of homozygous deletions of the CDKN2A gene

BackgroundNeuroblastoma is a very heterogeneous pediatric tumor of the sympathetic nervous system showing clinically significant patterns of genetic alterations. Favorable tumors usually have near-triploid karyotypes with few structural rearrangements. Aggressive stage 4 tumors often have near-diploid or near-tetraploid karyotypes and structural rearrangements. Whole genome approaches for analysis of genome-wide copy number have been used to analyze chromosomal abnormalities in tumor samples. We have used array-based copy number analysis using oligonucleotide single nucleotide polymorphisms (SNP) arrays to analyze the chromosomal structure of a large number of neuroblastoma tumors of different clinical and biological subsets.ResultsNinety-two neuroblastoma tumors were analyzed with 50 K and/or 250 K SNP arrays from Affymetrix, using CNAG3.0 software. Thirty percent of the tumors harbored 1p deletion, 22% deletion of 11q, 26% had MYCN amplification and 45% 17q gain. Most of the tumors with 1p deletion were found among those with MYCN amplification. Loss of 11q was most commonly seen in tumors without MYCN amplification. In the case of MYCN amplification, two types were identified. One type displayed simple continuous amplicons; the other type harbored more complex rearrangements. MYCN was the only common gene in all cases with amplification. Complex amplification on chromosome 12 was detected in two tumors and three different overlapping regions of amplification were identified. Two regions with homozygous deletions, four cases with CDKN2A deletions in 9p and one case with deletion on 3p (the gene RBMS3) were also detected in the tumors.ConclusionSNP arrays provide useful tools for high-resolution characterization of significant chromosomal rearrangements in neuroblastoma tumors. The mapping arrays from Affymetrix provide both copy number and allele-specific information at a resolution of 10–12 kb. Chromosome 9p, especially the gene CDKN2A, is subject to homozygous (four cases) and heterozygous deletions (five cases) in neuroblastoma tumors.

Expression patterns of S100A7 (psoriasin) and S100A9 (calgranulin-B) in keratinocyte differentiation

Abstract:u2002 S100 proteins are involved in many biological processes. S100A7 and S100A9 have been shown to be markedly upregulated both in ductal carcinoma in situ of the breast and in psoriasis. We have examined the relationship between keratinocyte differentiation and the expression of the two proteins. Using Western blot analysis and quantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR), both S100A7 and S100A9 were shown to be induced in normal primary keratinocytes (HEKn), when differentiation was promoted by high extracellular calcium, loss of contact with extracellular matrix and confluent conditions, as previously reported for S100A7 in mammary epithelial cells. Differentiation was confirmed by using RT‐PCR for the differentiation marker keratin‐1. Using immunohistochemistry with monoclonal antibodies, we compared the expression of the two proteins in a spectrum of conditions of dysregulated keratinocyte differentiation. We found a strikingly similar distribution of the proteins. Their expression correlated with the degree of keratinocyte differentiation. They were both absent in undifferentiated basalioma and strongly expressed in carcinoma in situ, as well as in keratoacanthoma and differentiated squamous cell carcinoma. In normal epithelium, they were expressed in the superficial, differentiated region of the epithelium rather than in the basal region. These findings support the hypothesis that these two S100 proteins are involved in keratinocyte differentiation.

Genetic counselling in psoriasis: empirical data on psoriasis among first‐degree relatives of 3095 psoriatic probands

The risk of getting psoriasis dependent on the occurence of psoriasis in the family has been determined empirically. Altogether 3717 families with one or both parents who had psoriasis have been analysed with regard to the number of children with or without psoriasis. The lifetime risk of getting psoriasis if no parent, one parent or both parents have psoriasis is 0.04, 0.28 and 0.65, respectively. If there is already one affected child in the family, the corresponding risks are 0.24, 0.51 and 0.83, respectively. The risk of getting psoriasis before the age of 32 years is dependent on the age‐of‐onset of psoriasis in one affected parent.

Stronger association with HLA-Cw6 than with corneodesmosin (S-gene) polymorphisms in Swedish psoriasis patients

Abstract Psoriasis vulgaris is strongly associated with certain human leukocyte antigens, especially in early onset. The purpose of this study was to study the HLA-Cw6 allele and its contribution to disease susceptibility in a set of 104 families with at least two affected siblings. A sequencing method was utilized to examine the two exons that build up the antigen binding site of the C locus receptor. DNA from patients homozygous for Cw6 based on haplotype information were sequenced. The results confirmed the identity of the Cw6 allele in affected individuals with the consensus sequence for Cw*0602. We screened the set of families for psoriasis patients homozygous for Cw6 and found 11 individuals with a mean age at onset of 16.1 years. The corresponding figure for the Cw6 heterozygotes was 18.45 years and for the Cw6-negatives 22.36 years. This is indicative of a gene dose effect. We performed a transmission disequilibrium test (TDT) on the Cw6 allele per se, used as a biallelic marker. The analysis resulted in a P -value of 5.3 × 10 –17 (t167/nt45). This greatly exceeds our previous results of a TDT in the region, including microsatellite markers and single nucleotide polymorphisms (SNPs) in the coding part of the S gene (corneodesmosin), which is a suggested candidate gene in the region. The maximum nonparametric linkage (NPL) value was also reached using HLA-C as a marker. We conclude that Cw6 is the allele which shows the highest degree of association with psoriasis in our set of families and we propose that it directly influences the age at onset of the disease rather than increasing the genetic load in accordance with a polygenic theory.

S100A7 (Psoriasin), highly expressed in Ductal Carcinoma In Situ(DCIS), is regulated by IFN-gamma in mammary epithelial cells

BackgroundThe aim of the present work was to explore signal transduction pathways used in the regulation of S100A7 (psoriasin). Members of the S100 gene family participate in many important cellular functions. Psoriasin, S100A8 (calgranulin A) and S100A9 (calgranulin B) are expressed in ductal carcinoma in situ (DCIS), as well as in the hyperproliferative skin disease, psoriasis. In the latter condition, a disturbance in the STAT pathway has recently been reported. This pathway is implicated in the regulation of IFN-gamma, widely recognized as a key cytokine in psoriasis. IFN-gamma also exerts anti-tumor action in a number of tumor cell types, including breast cancer. We therefore examined the effect of IFN-gamma and STAT-signaling on the psoriasin expression.MethodsWe established a TAC2 mouse mammary epithelial cell line with tetracycline-inducible psoriasin expression (Tet-Off). Viability in cell culture was estimated using MTS assay. Protein and gene expression were evaluated by Western blotting and quantitative real-time PCR. Statistical analyses were assessed using a one-tailed, paired t-test.ResultsWe report the downregulation of psoriasin by IFN-gamma in the MDA-MB-468 breast cancer cell line, as well as the downregulation of psoriasin induced by anoikis in cell lines derived from different epithelial tissues. In contrast, IFN-gamma had no suppressive effect on calgranulin A or calgranulin B. IFN-gamma is an important activator of the STAT1 pathway and we confirmed an active signaling pathway in the cell lines that responded to IFN-gamma treatment. In contrast, in the SUM190 breast carcinoma cell line, IFN-gamma did not suppress the expression of endogenous psoriasin. Moreover, a reduced phosphorylation of the STAT1 protein was observed. We showed that IFN-gamma treatment and the inhibition of the transcription factor NFkappaB had a synergistic effect on psoriasin levels. Finally, in TAC2 cells with tetracycline-induced psoriasin expression, we observed the increased viability of psoriasin-expressing cells after IFN-gamma treatment.ConclusionOur data support the possibility that psoriasin expression is transcriptionally suppressed by IFN-gamma and that this effect is likely to be mediated by the activation of the STAT1 signaling pathway. The increased viability of psoriasin-expressing cells after IFN-gamma exposure suggests that psoriasin expression leads to the development of an apoptosis-resistant phenotype.

Detection of psoriasin/S100A7 in the sera of patients with psoriasis

Backgroundu2002 Psoriasis is a disease of dysregulated inflammation and epithelial hyperproliferation in the skin, involving both the innate and adaptive immune system. Psoriatic keratinocytes express high levels of psoriasin (S100A7), a small calcium‐binding protein.