A TNF-alpha promoter polymorphism is associated with juvenile onset psoriasis and psoriatic arthritis

Polymorphisms in the TNF-alpha and TNF-receptor genes in patients with coronary artery disease

BACKGROUND

Coronary artery disease (CAD) is both multifactorial and polygenic in nature. Atheroma formation, the pathological hallmark of CAD, is an inflammatory process, with pro-inflammatory cytokines, such as tumour necrosis factor-alpha (TNF-alpha), having a major role in its pathogenesis. We have therefore investigated whether polymorphisms in the TNF-alpha (- 238 and - 308), TNF receptor 1 (position - 609 and + 10, intron 6) and TNF receptor 2 (position + 422, codon 198) genes show an association with CAD.

MATERIALS AND METHODS

Patients with angiographically proven single vessel (n = 58) and multivessel (n = 122) CAD were compared to patients with angiographically proven normal coronary arteries (n = 79) and volunteers without clinical evidence of CAD (n = 250). Genotyping was performed by PCR-RFLP analysis. For the TNF-alpha polymorphisms, a meta-analysis of all published studies was also undertaken.

RESULTS

No significant differences in allele or genotype frequencies were found between the normal coronary artery group or healthy volunteers and patients with CAD for any of the polymorphisms. There was also no difference in allele frequency between patients with single- and multivessel disease. For the - 308 and - 238 TNRalpha gene polymorphisms, a meta-analysis of our data and previously published studies failed to demonstrate any significant association with CAD.

CONCLUSIONS

Polymorphisms in the TNF-alpha promoter region and TNF-receptor genes are not associated with the development of CAD.

Disease mechanisms in psoriasis and psoriatic arthritis

Any hypothesis that tries to explain disease mechanisms in psoriasis and psoriatic arthritis (PsA) must take into account the containment of the inflammatory process to three specific sites: the skin, synovium, and enthesis. This article reviews the recent literature that advances our understanding of disease mechanisms at these specific sites. Additional progress will be achieved by research that focuses on common pathogenic pathways at these sites, in particular when searching for foreign candidates or auto-antigens triggering the T-cell-mediated immune response.

Psoriatic arthritis: clinical aspects, genetics, and the role of T cells

In the last 2 years there has been considerable progress in investigating the genetic and immunologic background of psoriasis and psoriatic arthritis. This review focuses on genetics and the role of T-cells in the immunopathogenesis of the disease, with particular reference to psoriatic arthritis.

Cytokine gene polymorphisms relevant for the spondyloarthropathies

Results of sibling and twin studies suggest that a substantial proportion of susceptibility to spondyloarthropathies arises from genes outside the human leukocyte antigen (HLA) region. There is increasing evidence that the pattern of cytokine secretion influences the course of spondyloarthropathies. A Th2 cytokine pattern (low tumor necrosis factor [TNF]-TNF-alpha low interferon [IFN]-gamma, and high interleukin [IL]-10) dominates in the joints of reactive arthritis patients. For IL-10 and TNF-alpha a substantial proportion of cytokine production is under genetic control and influenced by genetic polymorphisms. Here we review the evidences for association of TNF-alpha and IL-10 polymorphisms with spondyloarthropathies and their functional implications.

Polymorphism in MICA rather than HLA-B/C genes is associated with psoriatic arthritis in the Jewish population

The aim of this study was to examine whether the association of psoriatic arthritis (PsA) with human leukocyte antigen (HLA) class I genes is secondary to linkage disequilibrium with a nearby gene. We examined a sample of the Jewish population to investigate whether HLA-B/C and DR polymorphism is associated with susceptibility, or whether other closely related class I loci, such as the major histocompatibility complex class I chain-related gene A (MICA) and tumor necrosis factor (TNF), might play a role in disease development. Comparisons of different populations with different HLA profiles would be of value in identifying the candidate genes involved in PSA. Fifty-two patients with PsA and 73 random matched controls from a Jewish population were selected and DNA typed by polymerase chain reaction-single-strand oligonucleotide probe (PCR-SSOP) (HLA-C), PCR sequence-specific primers (PCR-SSP) (HLA-B, -DR), radioactive PCR (MICA-TM polymorphism in the transmembrane region), and PCR-RFLP (TNF). Some findings can be concluded from the study: (1) the frequency of HLA-B*5701, B*3801, B*39, B*27, Cw*0602, Cw*07, DRB1*0402, and DRB1*0701 were not found to be significantly increased in PsA; (2) no significant differences of TNFalpha promoter alleles at positions -308 and -238 were found between PsA and healthy controls; (3) the trinucleotide repeat polymorphism MICA-A9 was present at a higher frequency in PsA patients, (p(c) < 0.009, RR = 3.34, EF = 0.39); and (4) MICA-A9 polymorphism was found in linkage disequilibrium with HLA-B alleles (B*5701, B*3801) described to be associated with PsA in Caucasians. These results suggest that the MICA gene or other nearby gene(s) may be involved in the development of PsA, and it would thus appear that psoriasis vulgaris (PsV) and PsA are associated with different MHC susceptibility genes.

Interleukin-10 promoter polymorphism in psoriasis

Beneficial effects of interleukin-10 therapy and lower endogenous interleukin-10 formation compared with atopic dermatitis and cutaneous T cell lymphomas indicated that interleukin-10 is a key cytokine in psoriasis. The interleukin-10 promoter is highly polymorphic, with two informative microsatellites, interleukin-10.G and interleukin-10.R. In order to understand whether interleukin-10 itself is a predisposing gene for the psoriasis susceptibility we analyzed interleukin-10 promotor polymorphism in patients. The distribution of interleukin-10.G and interleukin10.R microsatellite alleles did not vary between patients (n = 78) and healthy controls (n = 80). In addition, when the psoriasis patients were stratified according to age of onset (younger than 40 y of age, or age 40 and older), no difference in allele distribution was observed; however, a clear differential distribution was revealed at the interleukin10.G locus when patients were stratified according to whether they had a positive family history of psoriasis (p = 0.04). This difference was due to an over-representation of the interleukin10.G13 allele in those patients with familial disease (40.4% vs 19.6%, Chi-square = 7.292, p = 0.007). The positive association of allele interleukin10.G13 with familial psoriasis was especially true when patients with an early onset (< 40 y of age) of the disease were compared with those patients with early onset against a nonfamilial background (39.6% vs 14.5%, Chi-square = 8.959, p = 0.003). Patients with age-of-onset of less than 40 were 4-fold [odds ratio = 3.85 (1.55--9.62)] more likely to have a psoriatic family background if they carried this interleukin10.G13 allele. These data suggest that the interleukin-10 locus contributes to the heritability of psoriasis susceptibility.

Allele-specific quantification of tumor necrosis factor alpha (TNF) transcription and the role of promoter polymorphisms in rheumatoid arthritis patients and healthy individuals

Interindividual variation in the expression of tumor necrosis factor alpha (TNF) suggests the existence of functionally distinct TNF alleles that could play a role in susceptibility to TNF associated diseases such as rheumatoid arthritis (RA). To determine whether differential expression of TNF alleles exists, the relative contribution of TNF alleles in total TNF RNA production in peripheral blood mononuclear cells (PBMC) of healthy individuals and synovial tissue of RA patients was analyzed. By using a Tai I restriction fragment length polymorphism (RFLP) located at position +489 in the first intron of the gene, the relative contribution of each allele in precursor transcript production in heterozygous individuals could be measured. By means of this method we studied whether differences exist between TNF alleles in TNF pre-mRNA production. The relative contribution of TNF alleles to the non-spliced RNA pool was measured in PBMC of healthy individuals which were stimulated with LPS, PMA and anti-CD3 and anti-CD28 monoclonal antibodies for different time periods. Moreover, synovial biopsy material of RA patients was analyzed. The results of this study do not reveal a difference in the contribution of distinct TNF alleles in TNF pre-mRNA production upon in vitro and physiological stimulation conditions in healthy individuals and RA patients. Since some of the individuals whose PBMC were tested were also heterozygous for either -308, -1031, -863, -857 TNF promoter/enhancer single nucleotide polymorphisms (SNPs), the data argue against functional relevance of these TNF promoter/enhancer SNPs in the regulation of transcription. In conclusion, the data do not provide evidence for the existence of transcriptionally distinct TNF alleles to explain interindividual variation in TNF expression.

Comparative association analysis reveals that corneodesmosin is more closely associated with psoriasis than HLA-Cw*0602-B*5701 in German families

HLA antigens are associated with psoriasis vulgaris across populations with different ethnic background. We have previously shown that in Caucasians this association is primarily based on the class I alleles of the extended HLA haplotype 57.1 (EH57.1/I), HLA-Cw6-HLA-B57. However, it remained unclear whether HLA-Cw6 itself or a closely linked locus predisposes to the disease. An interesting candidate for this presumed locus is corneodesmosin, which is exclusively synthesized in keratinocytes. The corneodesmosin gene locus (CDSN) is only 160 kb telomeric to HLA-C and tightly associated with psoriasis. In order to find out whether EH57.1/I or a corneodesmosin variant are the susceptibility determinants on 6p, HLA class I alleles and single-nucleotide polymorphisms (SNPs) of corneodesmosin were investigated at the sequence level and analyzed by comparative association tests. Transmission disequilibrium tests (TDT) were performed in 52 nuclear families, of which 36 were fully informative for a joint comparison of HLA and CDSN with regard to association to psoriasis. The extended TDT according to Wilson was employed to test for locus interaction. Using the HLA haplotype EH57.1/I and the CDSN haplotype formed by three intragenic variant sites at nt=619 (T), 1236 (T), and 1243 (C), we obtained the best resolution of parental transmission to index cases in the trio families. On direct comparison of the contributions of the HLA and the CDSN haplotypes, there was a markedly stronger association of the corneodesmosin TTC haplotype, which is not apparent in single locus analysis. We show furthermore that there is no higher order interaction between psoriasis, HLA, and CDSN. This lack of three-locus interaction is suggestive of two independent genetic contributions to psoriasis within the major histocompatibility complex (MHC).

Cytokine gene polymorphisms in psoriasis

BACKGROUND

Cytokine production is under genetic control, and certain allelic variants of cytokine genes are associated with higher or lower cytokine production in vitro and in vivo. Psoriasis is associated with an overexpression in the involved skin of T-helper cell type 1 (Th1) cytokines, e.g. interferon (IFN) -gamma and tumour necrosis factor (TNF) alpha and relative underexpression of Th2 cytokines, e.g. interleukin (IL) -4 and IL-10. Objective We investigated the hypothesis that allelic variants of genes for a high production of Th1 cytokines or TNF-alpha, or conversely low production of Th2 cytokines might represent a risk factor for developing psoriasis.

METHODS

Genotyping for IFN-gamma, IL-10, IL-4 and TNF-alpha was undertaken for 84 patients with psoriasis and compared with control data on file.

RESULTS

Genotype frequencies showed no differences between patients and controls for IFN-gamma, TNF-alpha or IL-4. For IL-10, patients with late onset psoriasis (over 40 years) were more likely to be heterozygous at position - 1082 (P = 0.02), corresponding to intermediate production of IL-10 in vitro and in vivo.

CONCLUSIONS

Psoriasis is not determined by a genotype consistent with high production of Th1 cytokines or low production of Th2 cytokines. Thus, the Th1 cytokine profile found in psoriatic plaques is most likely a consequence of local factors.

Tumor necrosis factor-alpha gene mutations and genotype changes in renal cell carcinoma

PURPOSE

We tested the hypothesis that genotype changes in the promoter region of tumor necrosis factor-alpha and exon 1 are associated with renal cell carcinoma.

MATERIALS AND METHODS

We analyzed genotypic changes at the 3 polymorphic loci of tumor necrosis factor-alpha -238, -308 and 488 using tumor and normal tissues from 81 Japanese patients with renal cell carcinoma.

RESULTS

Of the 81 patients 14 (17%) had point mutations from G to A, including 8 (57%) with point mutations at multiple loci. Six of the 8 patients (75%) with point mutations at multiple loci were classified with stage 4 renal cell carcinoma. Of the 81 patients 14 were classified with stage 4 carcinoma, including 9 (64%) with point mutation from G to A. Normal tissue from cancer patients showed an increased frequency of the GA genotype at loci -238 and 488 compared to healthy controls (37% versus 9% and 30% versus 12%, respectively). The relative risk of renal cell carcinoma was 6.5-fold higher in patients with the GA genotype at locus -238 (p <0.001) and 2.9-fold higher in those with the GA genotype at locus 488 (0.01 < p <0.025) when comparing normal tissue from renal cell carcinoma patients with that of healthy controls.

CONCLUSIONS

Point mutation from G to A, and the GA genotype at loci -238 and 488 of the TNF-alpha gene were common in patients with advanced renal cell carcinoma. The genotype change at loci -238 and 488 of the TNF-alpha gene are associated with renal cancer pathogenesis.

TNF-alpha gene polymorphism: clinical and biological implications

TNF-alpha is a proinflammatory cytokine that has been implicated in the severity of different immune-regulated diseases including autoimmune diseases and transplantation. The gene for TNF-alpha is located within the MHC region on chromosome 6p21.3. This is a highly polymorphic region, and the TNF-alpha itself contains a large number of polymorphisms. Some of these polymorphisms form extended haplotypes with the HLA class I and II alleles. TNF polymorphisms have been investigated in different diseases and most often whenever there is an HLA association with the disease (for example IDDM and RA) association(s) with TNF polymorphisms has been described. There are many studies on the function of the TNF polymorphisms showing the influence of the different alleles on the in vitro and in vivo levels of TNF production. However, recent studies in animal models suggest that not only polymorphisms within the TNF cluster are important in the regulation of TNF production but also the receptors as well (TNF R). This suggests that investigating polymorphisms within the TNF cluster and TNF receptors will be important in understanding the role of TNF regulation in a given disease.

Psoriatic arthritis

Psoriatic arthritis occurs in 5 - 42% of patients with psoriasis. It is an inflammatory arthritis distinct from rheumatoid, being usually sero-negative, asymmetrical and often affecting the spine, sacro-iliac and distal interphalangeal joints. It runs a very variable course, from a mild non-destructive disease to a severe rapidly progressive erosive arthropathy, producing an 'arthritis mutilans' with a combination of bone lysis and joint ankylosis. Its pathogenesis is not as well understood as rheumatoid arthritis, but is thought to be similarly immune driven, with a qualitatively similar immunomodulatory cascade and cytokine profile. Quantitatively, however, there are distinct differences in cell ratios and cytokine levels that may well impact on therapeutic strategies. Current therapies, such as methotrexate and sulphasalazine, have yet to be shown to be significantly more effective than placebo in delaying damage and produce only marginal improvements in symptoms. The newer specific biological agents, such as the anticytokine antibodies, interleukins and more specific anti-T-cell therapies, are starting to be studied in psoriatic arthritis. The rationale for their use comes mostly from extrapolation of their efficacy in rheumatoid arthritis. It has yet to be seen whether they will be efficacious in treating the osteolysis, fibrosis and new bone formation particular to psoriatic arthritis. Any treatment for the arthritis must also help the skin. Greater understanding of psoriatic arthritis, its pathogenesis and natural history is required if we are to target these exciting but expensive therapies effectively.

Different transcriptional activity and in vitro TNF-alpha production in psoriasis patients carrying the TNF-alpha 238A promoter polymorphism

Genes encoded on chromosome 6 within the major histocompatibility complex region are thought to play an important role in the pathogenesis of psoriasis. A potential candidate gene is tumor necrosis factor alpha. The tumor necrosis factor alpha promoter contains several polymorphisms including two G-->A transitions at position -308 and -238, which are the most common in Caucasian populations. The TNF238.2 (-238A) allele has been strongly associated with psoriasis. We have investigated the effect of the -238 and -308 variants on transcription of the tumor necrosis factor alpha gene in luciferase reporter gene assays. In addition, peripheral blood mononuclear cells of 47 patients with psoriasis and 43 controls were stimulated with different antigens and mitogens (streptococcal sonicate and superantigen, lipopolysaccharide, phorbol-12-myristate, phytohemagglutinin, CD3 antibodies) and tumor necrosis factor alpha production was measured in supernatants by enzyme-linked immunosorbent assay. The psoriasis-associated tumor necrosis factor alpha promoter allele TNF238.2 showed a significantly decreased transcriptional activity. Peripheral blood mononuclear cells carrying this allele produced significantly less tumor necrosis factor alpha after stimulation with T cell mitogens and streptococcal antigens in comparison to controls. The promoter allele TNF238.2 seems to influence tumor necrosis factor alpha production; a possible role in the pathogenesis of psoriasis has to be further evaluated.

A polymorphism of the 5' flanking region of tumour necrosis factor α gene is associated with thyroid-associated ophthalmopathy in Japanese

OBJECTIVE

We have studied the polymorphism of the 5' flanking region of the tumour necrosis factor (TNF)-α gene in order to better understand the genetic background of autoimmune thyroid disorders and thyroid-associated ophthalmopathy.

PATIENTS AND METHODS

We studied the polymorphism of the 5' flanking region of the TNF-α gene at positions - 1031 (T to C change, termed as - 1031C), - 863 (C to A, - 863 A), - 857 (C to T, - 857T), - 308 (G to A, - 308 A) and - 238 (G to A, - 238 A) in Japanese patients with Graves' disease [n = 173, 62 of whom had associated ophthalmopathy (American Thyroid Association (ATA) class III or greater)] and healthy control subjects (n = 575), using a polymerase chain reaction sequence-specific oligonucleotide probe method.

RESULTS

The allele frequency of - 857T in the Graves' disease patients (22.5% vs. 17.7%, OR  = 1.35, P  = 0.045, corrected P  = 0.23) was slightly greater than in the Japanese healthy subjects, respectively. However, the difference was not statistically significant. In Graves' disease patients with evident ophthalmopathy (ATA class III or greater), the allele frequencies of - 1031C and - 863 A were significantly greater than those with no or mild ophthalmopathy (ATA class 0-II) (31.5% vs. 13.5%, OR =2.94, P < 0.0001, corrected P < 0.0005; 23.4% vs. 11.7%, OR =2.30, P  = 0.0044, corrected P  = 0.022, respectively) and in control subjects. The strength of the association of the polymorphism - 1031C increased with the severity of ophthalmopathy, with odds ratios of 2.36 for ATA class III, and 5.43 for ATA class IV-VI, respectively, compared with Graves' disease with no or mild ophthalmopathy (ATA class 0-II). Although the phenotype frequency of DRB1*0901 was not different among Graves' disease patients with or without ophthalmopathy and control subjects, the phenotype frequency of DRB1*0901(-)/-1031C(+) was significantly increased in Graves' disease patients with ophthalmopathy compared to those with no or mild ophthalmopathy (OR = 4.91, P  = 0.0005) or control subjects (OR = 4.59, P < 0.0001).

CONCLUSIONS

These results suggest that the - 1031C or - 863 A alleles, or a gene in linkage disequilibrium with the TNF-α gene, predispose to the development of ophthalmopathy in Japanese patients with Graves' disease.

Celiac disease and TNF promoter polymorphisms

The possibility that genetic susceptibility to celiac disease (CD) might be influenced by tumor necrosis factor (TNF) genes polymorphism has repeatedly been put forward. To date, this has only been investigated in case-control studies and results have been contradictory. In order to avoid any possible ethnic mismatching between patients and controls, we have approached this problem studying 71 celiac families, establishing the parental haplotypes and comparing CD versus control haplotypes (the so-called AFBAC or affected family-based controls). We used DNA-based methods to screen for HLA-DRB1, -DQA1, and -DQB1 alleles, TNFalpha promoter polymorphims and TNFa and b microsatellites. The guanine-to-adenine polymorphism at position -308 of the TNFalpha gene promoter region was found associated with CD as the TNF-308A allele appeared significantly increased in frequency in CD haplotypes, and this was shown to be independent of the association between CD and the DRB1*0301,DQA1*0501,DQB1*0201 alleles. Our results indicate that at least another gene, in addition to the known association of CD with HLA class II, has a susceptibility role in this disease. This should be either TNFalpha or another polymorphic gene in the telomeric end of the HLA class III region.

PERB11 (MIC): a polymorphic MHC gene is expressed in skin and single nucleotide polymorphisms are associated with psoriasis

The susceptibility genes for psoriasis remain to be identified. At least one of these must be in the major histocompatibility complex (MHC) to explain associations with alleles at human leucocyte antigen (HLA)-A, -B, -C, -DR, -DQ and C4. In fact, most of these alleles are components of just two ancestral haplotypes (AHs) designated 13.1 and 57.1. Although relevant MHC gene(s) could be within a region of at least 4 Mb, most studies have favoured the area near HLA-B and -C. This region contains a large number of non-HLA genes, many of which are duplicated and polymorphic. Members of one such gene family, PERB11.1 and PERB11.2, are expressed in the skin and are encoded in the region between tumour necrosis factor and HLA-B. To investigate the relationship of PERB11.1 alleles to psoriasis, sequence based typing was performed on 97 patients classified according to age of onset and family history. The frequency of the PERB11.1*06 allele is 44% in type I psoriasis but only 7% in controls (Pc = 0.003 by Fisher's exact test, two-tailed). The major determinant of this association is a single nucleotide polymorphism (SNP) within intron 4. In normal and affected skin, expression of PERB11 is mainly in the basal layer of the epidermis including ducts and follicles. PERB11 is also present in the upper keratin layers but there is relative deficiency in the intermediate layers. These findings suggest a possible role for PERB11 and other MHC genes in the pathogenesis of psoriasis.

Polymorphism in the tumor necrosis factor B gene is associated with Palmoplantar pustulosis

We investigated the allele and genotype distribution of a polymorphism of the tumor necrosis factor (TNF) B gene and the frequency of HLA-DR9 in 49 patients with Palmoplantar pustulosis (PPP) and 51 healthy controls. We found that the frequency of TNFB2 in the PPP patients was significantly higher than that in the controls. Furthermore, the DR9-TNFB2 haplotype was significantly more frequent in the PPP patients (P=0.0045). These results suggest that TNFB2 may confer susceptibility to PPP.

Combined analysis of polymorphisms of the tumor necrosis factor-alpha and interleukin-10 promoter regions and polymorphic xenobiotic metabolizing enzymes in psoriasis

Environmental and genetic factors are thought to interact in the manifestation of psoriasis, but knowledge about the involved genes and antigens is incomplete. This study has focused on the association between psoriasis and inherited variations in xenobiotic metabolism and cytokine production as two components that may influence cutaneous immune responses to foreign substances. Polymorphisms of N-acetyltransferase 2, glutathione S-transferases T1 and M1, and promoter polymorphisms of the genes encoding for tumor necrosis factor-alpha and interleukin-10 were investigated in 151 Caucasian patients with psoriasis (100 with type I and 51 with type II psoriasis) and in 123 healthy controls. Polymorphisms were detected by polymerase chain reaction-based methods, restriction enzyme analysis, and direct sequencing. There were no significant differences in the distribution of enzyme polymorphisms or point mutations at position -1082 of the interleukin-10 promoter between the psoriasis groups and the control group. The G-->A polymorphism at position -238 of the tumor necrosis factor-alpha promoter (TNF alpha-238*A allele) was more common in type I psoriasis (27%) than in the controls [9.8%; odds ratio 3.4 (95% confidence interval 1.6-7.2); p = 0.0012; pcorr = 0.018]. Surprisingly, this overrepresentation of the tumor necrosis factor alpha-238*A allele was observed in male patients [4.1 (1.5-11.0); p = 0.0046; pcorr = 0.064] but not in female patients [1.8 (0.5-6.5); p = 0.5]. The G-->A polymorphism at position -308 of the tumor necrosis factor-alpha promoter was less frequent in type I psoriasis (23%) compared with controls (35.7%), although the negative association was weak [0.54 (0.3-0.97); p = 0.041; pcorr = not significant]. The distribution of the TNF alpha-238*A and TNF alpha-238*A alleles was similar in type II patients and controls. Our results suggest that male carriers of the G-->A polymorphism at position -238 of the tumor necrosis factor-alpha promoter are at an increased risk to develop early-onset psoriasis.

A polymorphism that affects OCT-1 binding to the TNF promoter region is associated with severe malaria

Genetic variation in cytokine promoter regions is postulated to influence susceptibility to infection, but the molecular mechanisms by which such polymorphisms might affect gene regulation are unknown. Through systematic DNA footprinting of the TNF (encoding tumour necrosis factor, TNF) promoter region, we have identified a single nucleotide polymorphism (SNP) that causes the helix-turn-helix transcription factor OCT-1 to bind to a novel region of complex protein-DNA interactions and alters gene expression in human monocytes. The OCT-1-binding genotype, found in approximately 5% of Africans, is associated with fourfold increased susceptibility to cerebral malaria in large case-control studies of West African and East African populations, after correction for other known TNF polymorphisms and linked HLA alleles.

Polymorphism within the tumor necrosis factor alpha (TNF) promoter region in patients with ankylosing spondylitis

In addition to HLA-B27, other genetic factors are thought to be involved in the pathogenesis of ankylosing spondylitis (AS). Because of the location of the TNF gene in the vicinity of the HLA-B locus, and the prominent role in inflammation of its product, we investigated the association between AS and two G to A transition polymorphisms located at position -238 and -376 in the promoter region of the TNF gene. The distribution of the TNF alleles was determined in 86 HLA-B27+ AS patients and 163 healthy controls. From the 86 AS patients, 33 suffered from acute anterior uveitis (AAU). No significant difference for the TNF-376 polymorphism in AS and healthy controls was observed. The frequency of the TNF-238A allele in HLA-B27+ AS patients was significantly decreased compared to random controls (p = 0.021). However, the frequency of the TNF-238A allele in HLA-B27+ AS patients was not significantly different from that observed in HLA-B27+ healthy individuals (p = 0.6). Assessment of association showed that the TNF-238G allele is in linkage disequilibrium with the HLA-B27 allele (delta = 0.053; P = 0.008). Therefore, we conclude that the association between TNF-238G and AS is secondary to the HLA-B27 gene and that TNF-238 and-TNF-376 alleles are not likely to be involved in the susceptibility to AS.

Linkage disequilibrium analysis of familial psoriasis: identification of multiple disease-associated MHC haplotypes

Although psoriasis vulgaris (PsV) is strongly associated with certain human leukocyte antigens, the pathogenetic nature of these associations remains elusive. The objectives of this study were: (i) to determine whether HLA loci directly determine susceptibility or merely serve as markers for the susceptibility allele; and (ii) to identify additional disease-associated haplotypes. By applying maximum likelihood linkage disequilibrium analysis (LDA) in cases vs. controls, we found the susceptibility gene to be more strongly associated with specific HLA haplotypes than with their component alleles. Stronger linkage disequilibrium between PsV and HLA alleles was detected at HLA-C and HLA-B than at DRB1 and DQB1. Parametric linkage analysis accounting for marker-trait disequilibrium in psoriasis vulgaris pedigrees yielded most significant results for a locus close to HLA-B and -C. Furthermore, we found that susceptibility is linked to at least three different ancestral HLA haplotypes; among them, HLA-Cw7-B8-DRB1*0301-DQB1*02 is linked to PsV for the first time. These results identify a major PsV susceptibility locus in the immediate vicinity of, but distinct from HLA-B or HLA-C, and suggest that multiple disease alleles have arisen during human evolution.

Vitamin D receptor polymorphism is associated with psoriasis

Vitamin D receptor is a trans-acting transcriptional factor that mediates 1alpha,25-dihydroxyvitamin D3 action in the regulation of target gene expression. Recent studies have shown that clinical response of psoriasis to 1alpha,25-dihydroxyvitamin D3 is correlated with the vitamin D receptor mRNA expression level, which may be influenced by the genotype of the vitamin D receptor. In this study, we have explored a possible association between psoriasis and the polymorphism in the gene encoding the vitamin D receptor. We examined the allelic frequencies of the vitamin D receptor in psoriasis patients (n = 104) and in healthy controls (n = 104) by analyzing the restriction pattern of the polymerase chain reaction products. A significant increase in the frequency of the A allele (absence of the restriction site at intron 8) by ApaI restriction fragment length polymorphism was observed in psoriasis patients compared with that of the control group, and the tendency was more accentuated in early onset psoriasis. Odds ratios (95% confidence interval) for psoriasis of AA and Aa genotypes were 5.0 (1.3-19.1) and 2.4 (1.3-4.3), and odds ratios for early onset of AA and Aa genotypes were 6.4 (1.6-25.0) and 3.1 (1.7-5.9), respectively. Allele frequencies for A and a alleles were 0.317 and 0.683 in the psoriasis group and 0.168 and 0.832 in the control group (p = 0.001). A significant association between vitamin D receptor genotypes and the mean age at onset was observed (p < 0.05). Our findings suggest that allelic variance in the vitamin D receptor gene itself or other genes in linkage disequilibrium with this gene, could predispose to the development of psoriasis.

The immunogenetics of the seronegative spondyloarthropathies

In none of the rheumatic diseases has the genetic contribution to pathogenesis been so well characterized as in the seronegative spondyloarthropathies. Most important has been the elucidation of the structure and effect on disease expression of HLA-B27, where 11 subtypes have been distinguished to date. These vary in frequency in different ethnic groups and seem to show differential disease associations. The high frequency of this gene in patients with the seronegative spondyloarthropathies, especially ankylosing spondylitis (AS) and Reiter's syndrome (RS)/reactive arthritis (ReA), has emerged as probably the best example of a disease association with a hereditary marker. Other HLA genes, in addition to HLA-B27, have been implicated in psoriasis and psoriatic arthritis. These include those from the HLA-C locus and from HLA-DR. In addition, recent family studies have implicated other genes outside the MHC that further enhance the susceptibility to AS.

Association of different tumor necrosis factor alpha promoter allele frequencies with ankylosing spondylitis in HLA-B27 positive individuals

OBJECTIVE

To investigate the potential association of tumor necrosis factor alpha (TNFalpha) promoter alleles with ankylosing spondylitis.

METHODS

DNA from 141 HLA-B27 positive Caucasian patients with ankylosing spondylitis and 46 B27-positive and 99 B27-negative healthy Caucasian controls was investigated by polymerase chain reaction amplification of the TNFalpha promoter region and subsequent dot-blot analysis with allele-specific oligonucleotides.

RESULTS

There was a significant decrease in the promoter alleles TNF-238.2 and TNF-308.2 in the ankylosing spondylitis group (266 wild-type alleles, 16 variant alleles) compared with the B27-positive (75 wildtype promoter alleles, 17 variant alleles; P<0.0004) and the B27-negative (159 wild-type promoter alleles, 39 variant alleles; P< 0.00001) control groups. Positivity for the variant promoter alleles conferred protection and a relative risk of 0.3 to B27-positive individuals.

CONCLUSION

These data indicate that allelic variations in the TNFalpha promoter influence disease susceptibility in HLA-B27 positive individuals. This protective effect of variant promoter alleles could be related to differences in TNFalpha production or could reflect the association of different B27 haplotypes with ankylosing spondylitis.

Psoriasis: A possible reservoir for human papillomavirus type 5, the virus associated with skin carcinomas of epidermodysplasia verruciformis

Recent polymerase chain reaction data have shown that most human papillomavirus (HPV) genotypes associated with epidermodysplasia verruciformis (EV) are widespread; however, HPV5 associated with EV skin carcinomas has only rarely been detected in non-EV patients. To identify the reservoir of this virus, we examined 335 sera from different groups of patients for the presence of HPV5 antibodies by an enzyme-linked immunosorbent assay test based on HPV5 virus-like particles. The prevalence of antibodies reacting with HPV5 virus-like particles was found to be significantly higher in psoriatic patients (24.5%) than in other groups (2-5%), including patients with atopic dermatitis and renal transplant recipients. Analysis of scrapings of lesional and uninvolved skin by a nested polymerase chain reaction method, using degenerate EV HPV primers, disclosed HPV DNA in 91.7% of 48 psoriatic skin samples and 35.5% of 31 atopic dermatitis specimens. Eleven EV HPV genotypes, most frequently HPV5 and HPV36, and a putative novel genotype (PsoX1) were identified in psoriasis. Five EV HPV genotypes and two putative novel genotypes (ADX1 and ADX2) were detected in atopic dermatitis patients. HPV5 was not found in atopic dermatitis patients. Using type specific primers, HPV5, HPV36, and HPV1 were found in 89.4%, 84.2%, and 42.1% of specimens from psoriatic patients, whereas HPV36 was detected in 22.5% of specimens from atopic dermatitis patients. HPV16 was never detected. On the whole, 27 HPV5 and 13 HPV36 DNA variants were disclosed after sequencing amplification products. Our data confirm that EV HPV are widespread and point to psoriasis as a reservoir for HPV5. Whether HPV5 is involved in the pathogenesis of psoriasis remains to be determined.