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

Psoriasis and psoriatic arthritis: separate or one and the same?

The presence and severity of skin and joint symptoms in patients with psoriasis and psoriatic arthritis frequently do not correspond, a discrepancy that has raised the question of whether they represent two related but different disease processes. The fact that some agents seem to work preferentially in one state over the other reinforces this idea. However, there are also several agents with combined efficacy against cutaneous and articular inflammation that appear to support the existence of a common aetiology. Here we review the clinical, epidemiological and genetic evidence for and against a common pathogenesis for the two diseases. We then discuss the cellular and molecular targets of their selected therapies and how they potentially implicate effector pathways as a common immunopathogenic mechanism. Finally, we examine a recently proposed model of psoriasis pathogenesis involving type 1 interferon-producing plasmacytoid dendritic cells and how it may provide further clues to the aetiological links between psoriasis and psoriatic arthritis.

Pathogenetic and clinical rationale for TNF-blocking therapy in psoriatic arthritis

The classical definition of psoriatic arthritis (PsA) as an inflammatory arthritis associated with psoriasis reflects only in part the large spectrum of musculoskeletal disorders found in patients with psoriasis. In particular, enthesopathy, dactilytis, osteitis and axial involvement are frequently neglected and probably account for the unsatisfactory response of PsA to traditional drugs, such as NSAIDs, steroids and DMARDs. Furthermore, these drugs showed only a partial ability to influence radiographic progression and psoriasis. The new anti-TNF agents, in particular etanercept but also infliximab and adalimumab, have demonstrated a comprehensive effectiveness on the multiple aspects of the PsA disease, including quality of life and slowing of radiographic progression. Despite this clear efficacy, the actual mechanisms by which TNF-blocking agents are able to obtain all these effects are still incompletely understood. However, the success of this therapy suggested one of the best ways for further research in the field of PsA. In this new fashion, the most stimulating hypotheses involving TNF are those regarding genetic predisposition, angiogenesis and osteoclastogenesis.

TNF-α Gene Promoter -238G>A and -308G>A Polymorphisms Alter Risk of Psoriasis Vulgaris: A Meta-Analysis

Tumor necrosis factor-alpha (TNF-alpha) is a major proinflammatory cytokine and involved in the etiology of psoriasis. The -238G>A and -308G>A polymorphisms influence the transcription of the TNF-alpha gene and have been implicated in psoriasis risk. However, the results from the published studies on the association between TNF-alpha polymorphisms and psoriasis risk are conflicting. Our meta-analysis of a total of 997 psoriasis cases and 943 control subjects from eight published case-control studies for the -238G>A polymorphism and of 1,156 psoriasis cases and 1,083 control subjects from 10 published case-control studies for the -308G>A polymorphism showed that a significantly increased risk was associated with the variant GA+AA genotypes of -238G>A, compared with the GG genotype (odds ratio (OR) 2.60, 95% confidence interval (95% CI) 1.48-4.56), whereas a significantly reduced psoriasis risk was associated with the variant GA+AA genotypes of the -308G>A compared with the GG genotype (OR 0.57, 95% CI 0.45-0.71). Our findings suggest that TNF-alpha -238G>A and -308G>A polymorphisms might be used as biomarkers for psoriasis risk prediction. A single larger study with thousands of subjects and biochemical and biological characterization is warranted to evaluate further the role of -238G>A and -308G>A polymorphisms and psoriasis risk in a population of various ethnicities.

Associations of promoter region polymorphisms in the tumour necrosis factor-? gene and early-onset psoriasis vulgaris in a northern Polish population

BACKGROUND

Tumour necrosis factor (TNF)-alpha is considered to be an important mediator in the pathogenesis of psoriasis. Increased levels and activity of this cytokine have been observed in blood and skin of patients with psoriasis. As certain allelic variants of the TNF-alpha gene are associated with increased or decreased production of TNF-alpha, the disturbed cytokine balance may be under genetic control.

OBJECTIVES

To investigate the potential association of TNF-alpha promoter alleles within subtypes of psoriasis compared with healthy controls in a northern Polish population.

METHODS

We analysed 166 patients with psoriasis vulgaris (134 with type I and 32 with type II) and 65 healthy controls. The polymorphisms -238G/A and -308G/A in the promoter region of the TNF-alpha gene were typed using the amplification refractory mutation system-polymerase chain reaction method.

RESULTS

We found that the TNF-alpha-308A allele frequency was significantly decreased among patients with early-onset psoriasis in comparison with control subjects (7.5% vs. 15.4%, P = 0.022), whereas in the same patients the frequency of the TNF-alpha-238A allele was significantly increased as compared with the controls (16.8% vs. 3.1%, P = 0.000017, odds ratio 8.79, 95% confidence interval 2.606-29.678). Patients with early-onset psoriasis with -238 genotype GA or AA were found more often among those with age at onset < 25 years in comparison with those with genotype GG (31.7% vs. 9.1%, P = 0.0312). We also found that the mean +/- SD age at onset among -238A carriers was significantly lower in comparison with that associated with the -238GG genotype (13.5 +/- 7.4 vs. 19.2 +/- 9.9 years, P = 0.0132).

CONCLUSIONS

Our study confirming the association between -238 G/A TNF-alpha promoter polymorphism and early-onset psoriasis vulgaris in the northern Polish population suggests that the -238A variant may contribute not only to a predisposition to psoriasis vulgaris but also to the disease phenotype.

Cytokine gene polymorphisms in Chinese patients with psoriasis

BACKGROUND

Previous studies have shown that cytokine gene polymorphisms may confer susceptibility to psoriasis.

OBJECTIVES

To determine whether genetic polymorphisms of the cytokine genes might influence the development of psoriasis in Chinese patients in Taiwan.

METHODS

DNA samples were obtained from 170 patients with psoriasis vulgaris (PV), 102 patients with psoriatic arthritis (PsA) and 210 control subjects. Using direct sequencing and microsatellite genotyping, we examined 28 polymorphisms in 11 cytokine genes including the interleukin (IL)-1alpha, IL-1beta, IL-1 receptor antagonist, IL-4, IL-8, IL-10, IL-12B, IL-13, tumour necrosis factor (TNF)-alpha, TNF-beta and interferon-gamma genes. Genotypes of HLA-Cw*0602, killer cell immunoglobulin-like receptor (KIR) genes and major histocompatibility complex class I chain-related gene A (MICA) were also determined in patients with PsA.

RESULTS

The patients with PV were more likely to carry the +4496G allele of the IL-12B gene (59.4% vs. 49.3%, P = 0.0067, P(c) = 0.033). However, no significantly different allelic and genotypic distributions of the other analysed genes including IL-1beta, TNF-alpha, TNF-beta, KIR genes and MICA were found between the PV/PsA patients and controls. Moreover, no association was observed with disease onset, gender, peripheral arthritis or joint erosion. With regards to HLA-Cw*0602, its allele frequency was significantly increased in patients with early-onset PV (25.3% vs. 4.8%, P < 10(-7)), but not in patients with PsA.

CONCLUSIONS

The IL-12B gene polymorphism conferred a risk for PV in our Chinese population, although the effect was more minor than that of HLA-Cw*0602. Cw*0602, KIR2DS1/S2 and MICA-A9 were unlikely to be risk alleles in our patients with PsA. The other analysed genetic polymorphisms of cytokine genes do not appear to be associated with susceptibility to PV and PsA in Chinese patients in Taiwan.

Psoriasis, innate immunity, and gene pools

Recently, emphasis has shifted from T cells to innate (natural) immunity as the possible major culprit in psoriasis. All known elements of innate immune responses are up-regulated in psoriasis lesions, which must have a polygenetic origin. We hypothesize that urbanized populations have been under evolutionary pressure that selects for increased innate immunity responses because those offer relative but immediate protection from epidemic infections. That would have resulted in a changing gene pool, in which alleles of polymorphisms associated with increased innate immunity responses have amplified in these populations. Having too many of these genes together in one individual would result in a relatively low number of infections. On the other hand, it would also result in a higher prevalence of diseases related to increased innate immunity, such as psoriasis, and perhaps also multiple sclerosis and rheumatoid arthritis. Indeed, in indigenous people (Inuit, Aborigines, Ami) who have not been under this selection pressure, morbidity due to infections is high and the prevalence of psoriasis is low or even absent.

TNF polymorphisms in psoriasis: Association of psoriatic arthritis with the promoter polymorphismTNF*-857 independent of thePSORS1 risk allele

OBJECTIVE

Single-nucleotide polymorphisms (SNPs) of the tumor necrosis factor gene TNF at positions -238 and -308 have been associated with psoriasis vulgaris and psoriatic arthritis (PsA). The strong linkage disequilibrium (LD) at chromosome region 6p21, a region known to harbor risk factors for psoriasis susceptibility (PSORS1) other than just SNPs of the TNF gene, renders the interpretation of these findings difficult. The aim of this study was to analyze several SNPs of the TNF gene and its neighboring LTA gene for independent and dependent carriage of the PSORS1 risk allele.

METHODS

SNPs in the promoter of the TNF (-238G/A, -308G/A, -857C/T, and -1031T/C), LTA (+252A/G), TNLFRSF1A (+36A/G), and TNLFRSF1B (+676T/G) genes were genotyped in 375 psoriasis patients, 375 PsA patients, and 376 controls. The Trp- Trp-Cys-Cys haplotype of the CCHCR1 gene (CCHCR1*WWCC) was used as an estimate of the risk allele PSORS1.

RESULTS

Whereas we were able to confirm the previously described strong association of allele TNF*-238A with psoriasis, our study revealed that this association was completely dependent on carriage of the PSORS1 risk allele. For PsA, but not psoriasis vulgaris without joint involvement, a strong association with the allele TNF*-857T (odds ratio 1.956 [95% confidence interval 1.334-2.881]; corrected P = 0.0025) was also detected in patients negative for the PSORS1 risk allele.

CONCLUSION

Our results indicate that there are genetic differences between psoriasis vulgaris patients with and without joint manifestations. While the previously reported association between TNF*-238A and psoriasis seems to primarily reflect LD with PSORS1, TNF*-857T may represent a risk factor for PsA that is independent of the PSORS1 allele.

Infliximab inhibits progression of radiographic damage in patients with active psoriatic arthritis through one year of treatment: Results from the induction and maintenance psoriatic arthritis clinical trial 2

OBJECTIVE

To evaluate the effect of infliximab on progression of structural damage over 1 year in patients with active psoriatic arthritis (PsA) enrolled in the Induction and Maintenance Psoriatic Arthritis Clinical Trial 2.

METHODS

In this double-blind, placebo-controlled study, 200 patients with active PsA were randomly assigned (1:1 ratio) to receive infusions of infliximab (5 mg/kg) or placebo at weeks 0, 2, and 6, and every 8 weeks thereafter through week 54. At week 24, patients initially assigned to receive placebo crossed over to receive infliximab (5 mg/kg). Based on predefined criteria, patients randomized to receive placebo could enter early escape by receiving infliximab (5 mg/kg) starting at week 16, and patients randomized to receive infliximab could have the dose increased to 10 mg/kg starting at week 38. Patients were analyzed according to the treatment they were randomized to receive. Radiographs of hands and feet were obtained at baseline and at weeks 24 and 54. Two readers blinded to treatment assignment and radiograph sequence independently evaluated erosions and joint space narrowing using the Sharp/van der Heijde scoring method modified for PsA.

RESULTS

At week 24, patients randomized to receive infliximab 5 mg/kg had significantly less radiographic progression compared with patients randomized to receive placebo, with mean +/- SD changes from baseline in the total Sharp/van der Heijde score of -0.70 +/- 2.53 and 0.82 +/- 2.62, respectively (P < 0.001). At week 54, mean +/- SD changes from baseline in the total Sharp/van der Heijde score were -0.94 +/- 3.40 in patients randomized to receive infliximab and 0.53 +/- 2.60 in those receiving placebo/infliximab (P = 0.001).

CONCLUSION

Infliximab significantly inhibits radiographic progression in patients with PsA as early as 6 months after starting treatment, and the beneficial effect continues through 1 year of infliximab therapy.

Non-B27 MHC associations of ankylosing spondylitis

Ankylosing spondylitis (AS) has been associated with human leukocyte antigen (HLA)-B27 for over 30 years; however, the mechanism of action has remained elusive. Although many studies have reported associations between AS and other genes in the major histocompatibility complex (MHC) in AS, no conclusive results have emerged. To investigate the contribution of non-B27 MHC genes to AS, a large cohort of AS families and controls were B27 typed and genotyped across the region. Interrogation of the data identified a region of 270 kb, lying from 31 952 649 to 32 221 738 base pairs from the p-telomere of chromosome 6 and containing 23 genes, which is likely to include genes involved with susceptibility to AS.

Infliximab maintains a high degree of clinical response in patients with active psoriatic arthritis through 1 year of treatment: results from the IMPACT 2 trial

OBJECTIVE

To evaluate the efficacy and safety of infliximab through 1 year in patients with psoriatic arthritis (PsA) enrolled in the IMPACT 2 trial.

METHODS

In this double blind, placebo controlled, phase III study, 200 patients with active PsA were randomised to receive infusions of infliximab 5 mg/kg or placebo at weeks 0, 2, 6, and every 8 weeks thereafter through 1 year. Patients with persistent disease activity could enter early escape at week 16, and all remaining placebo patients crossed over to infliximab at week 24. Patients randomised to infliximab who had no response or who lost response could escalate their dose to 10 mg/kg starting at week 38. Clinical efficacy was assessed based on the proportion of patients achieving ACR 20 and PASI 75 responses. Major clinical response (that is, maintenance of ACR 70 response for 24 continuous weeks) was assessed for the first time in PsA.

RESULTS

Through 1 year of treatment, 58.9% and 61.4% of patients in the randomised infliximab and placebo/infliximab groups, respectively, achieved ACR 20; corresponding figures for PASI 75 were 50.0% and 60.3%. At week 54, major clinical response was achieved by 12.1% of patients in the infliximab group. The safety profile of infliximab through week 54 was consistent with that seen through week 24. Two malignancies occurred: basal cell skin cancer (placebo) and stage I Hodgkin's lymphoma (infliximab).

CONCLUSION

Infliximab maintains a high degree of clinical efficacy and continues to be well tolerated in patients with PsA through 1 year of treatment.

Pharmacogenetic of antirheumatic treatments: clinical implications

Preliminary pharmacogenetic data suggest that germline genetic informations might be of value in individualizing disease-modifying antirheumatic drugs (DMARDs) therapy in various autoimmune chronic inflammatory diseases. Either DMARDs small molecules (DMARDs-SM) or DMARDs biological therapies (DMARDs-BT) might be selected for their lower toxicity or better efficacy based on single-nucleotide polymorphisms (SNPs) of genes governing the metabolism of drugs, or the response of immune cells to proinflammatory molecules, or the proinflammatory molecular activity of immune cells. Data available for one DMARDs-SM, methotrexate, suggest that a careful assessment of the SNPs of four enzymes involved in the folate metabolism allow one to construct a genetic index of toxicity (toxicogenetic index) that might be employed in daily practice to find the patient's most at risk. Only the full knowledge of the various gene polymorphisms controlling the phenotypic manifestations of the inflammatory-immunological milieu of each rheumatic disease will allow one to obtain the clear definition of a personalized medicine. Few different cytokine gene SNPs seem to be of importance in determining the susceptibility to diseases, or the aggressiveness of diseases. The role of genetics in affecting a possible clinical response to DMARDs-BT targeting specific inflammatory molecules or their receptors still has to be defined. However, the available data suggest that cytokine (and/or receptors) gene SNPs might indeed play a role in determining the biological effects, hence the clinical effectiveness of DMARDs-BT. Crucial to this aim will be the prospective analysis of clinical benefits and safety on the basis of the at baseline stratification of gene SNPs in each chronic inflammatory rheumatic disease before starting any new DMARDs-SM or DMARDs-BT.

Polymorphisms within the tumor necrosis factor-alpha promoter region in patients with HLA-B27-associated uveitis: association with susceptibility and clinical manifestations

PURPOSE

The existence of genetic variations in a number of cytokines has been considered to influence susceptibility or relate to disease severity in various autoimmune diseases. Among these, single-nucleotide polymorphisms (SNPs) of the tumor necrosis factor alpha (TNF-alpha) promoter at nucleotides -308 and -238 are considered to be protective against inflammation in HLA-B27-positive individuals, whereas the SNP at position -857 has been associated with disease development in anterior uveitis. We investigate a hypothesized association between the TNF-alpha -857 C-to-T, -308 G-to-A, and the TNF-alpha -238 G-to-A SNPs and the presence of HLA-B27-associated uveitis.

DESIGN

Retrospective case-control study.

PARTICIPANTS

One hundred fourteen Caucasian patients with HLA-B27-associated uveitis were studied. Mean age of patients was 44.9+/-14 years (range, 16-81), and mean duration of HLA-B27-associated uveitis was 115.6+/-104 months (range, 6 months-51 years). Eighty-six patients (75.4%) suffered from an additional systemic manifestation of the disease. Sixty-three unrelated healthy HLA-B27-positive blood donors and 88 unrelated healthy HLA-B27-negative individuals served as controls.

METHODS

Genotypes were determined by polymerase chain reaction.

MAIN OUTCOME PARAMETERS

Association of genotypes at positions -857, -308, and -238 of the TNF-alpha gene with disease development.

RESULTS

Frequencies of the TNF-alpha -308GA and TNF-alpha -238GA genotypes were significantly lower in patients with HLA-B27-associated uveitis (6.1% and 0%, respectively) when compared with the HLA-B27-negative control group, 23% at -308 (P = 0.003), and 7.9% at -238 (P = 0.0003). When compared with healthy HLA-B27-positive controls, a significantly lower frequency of the TNF-alpha -238GA genotype was found among patients (6.3%, P = 0.015). The frequency of the TNF-alpha -308GA genotype was also found to be lower in patients than among HLA-B27-positive control subjects, without, however, reaching statistical significance (6.1%, P = 0.07). No difference in frequencies was seen among the different groups for the SNPs at position -857.

CONCLUSION

Our data suggest that HLA-B27-positive individuals show a higher susceptibility towards development of an intraocular inflammation in the presence of an A allele at nucleotide -238 and, to a lesser degree, at nucleotide -308 of the TNF-alpha gene promoter.

Anti-TNF alpha dans le traitement du rhumatisme psoriasique

Psoriatic arthritis is an inflammatory and possibly destructive form of arthritis. As in rheumatoid arthritis and ankylosing spondylitis, the use of biological therapy in psoriatic arthritis is a therapeutic revolution: both articular and cutaneous efficacy have been shown, and some improvement is visible on radiography. The benefit-risk ratio will improve when we learn to identify more accurately the patients likely to benefit from these treatments.

TNFalpha polymorphisms and risk of psoriatic arthritis

BACKGROUND

Tumour necrosis factor alpha (TNFalpha) is a cytokine of critical importance in psoriatic arthritis.

OBJECTIVES

(1) To examine the association between TNFalpha promoter gene polymorphisms and psoriatic arthritis in two well characterised Canadian populations with the disease; (2) to carry out a meta-analysis of all TNFalpha association studies in white psoriatic arthritis populations.

METHODS

DNA samples were genotyped for five TNF variants by time of flight mass spectrometry using the Sequenom platform. All five single nucleotide polymorphisms were in the 5' flanking region of TNFalpha gene at the following positions: -1031 (T-->C), -863 (C-->A), -857 (C-->T), -308 (G-->A), and -238 (G-->A). Primary analyses were based on logistic regression. Summary estimates of disease/genotype relations from several studies were derived from random effects meta-analyses.

RESULTS

237 psoriatic arthritis subjects and 103 controls from Newfoundland and 203 psoriatic arthritis subjects and 101 controls from Toronto were studied. A combined analysis of data from both populations, showed a significant association between disease status and the -238(A) variant (p=0.01). The meta-analysis estimate for the -238(A) TNFalpha variant in eight psoriatic arthritis populations was also significant (odds ratio=2.29 (95% confidence interval, 1.48 to 3.55)).

CONCLUSIONS

Analysis of TNFalpha variants in psoriatic arthritis populations shows that the -238 (A) variant is a significant risk factor for this disease.

Psoriatic arthritis: pathogenesis and novel immunomodulatory approaches to treatment

Psoriatic arthritis (PsA) is a chronic inflammatory arthropathy characterized by the association of arthritis and psoriasis. PsA runs a variable course, from mild synovitis to severe, progressive, erosive arthropathy. The pathogenesis of PsA involves alteration in the components of the immune response, although the exact cause of PsA is unknown. A number of patients with severe peripheral arthritis fail to respond to standard conventional therapy. Advances in biotechnology and in our understanding of the immunopathogenesis of PsA have led to great interest and progress in regards to biologic treatments for PsA. Notable success achieved with recently introduced biologic therapies has paved the way for further research and development of additional therapies that should improve outcomes for affected patients.

Tumor necrosis factor-alpha in psoriasis and psoriatic arthritis: a clinical, genetic, and histopathologic perspective

The successful introduction of anti-tumor necrosis factor (TNF) therapies in psoriasis and psoriatic arthritis has sharpened considerable interest in this chronic and frequently disabling disease. Unlike the situation in rheumatoid arthritis, where anti-TNF therapies were introduced after years of painstaking research which confirmed a key proinflammatory role for TNF, the evidence for TNF having a key role in psoriatic arthritis has lagged behind. In this paper, the emerging immunohistochemical, genetic, and clinical literature relating to TNF's role in skin and joint manifestations of this disease is reviewed and areas for future research are suggested.

Psoriasis: dysregulation of innate immunity

The current understanding of the function of natural killer (NK) T cells in innate immunity and their potential to control acquired specific immunity, as well as the remarkable efficacy of antitumour necrosis factor-alpha biological treatments in psoriasis, forces us to refine the current T-cell hypothesis of psoriasis pathogenesis, and to give credit to the role of innate immunity. Psoriasis might be envisioned to be a genetically determined triggered state of otherwise dormant innate immunity. This aggravated state of innate immunity is represented by the activity of NK T cells, dendritic cells, neutrophils and keratinocytes, leading to the recruitment and activation of preferentially type 1 T cells, possibly in an antigen-independent way. Keratinocytes in psoriasis then are sensitive to the effects of T-cell activation and cytokine production, interferon (IFN)-gamma, by responding with psoriasiform hyperplasia. The chronic inflammation of psoriatic lesions suggests that this might be due to a deficiency in downregulation processes (e.g. a defect in the regulatory T-cell repertoire) and/or the persistence of an unknown trigger resulting in an exaggerated innate immune response.

Animal models of psoriasis

Psoriasis is a common and chronic skin disorder under active investigation around the world. Despite this, determination of its genetic basis, role of the immune system in the disease pathophysiology and development of effective therapy, have been hampered severely by the absence of any spontaneous psoriatic skin disease in animals. Furthermore, until recently, validated animal models designed to create psoriasis were unavailable to investigative skin biologists and clinical scientists. However, there is at least one animal model which has been established and validated; it uses human skin engrafted on to severe combined immunodeficient (SCID) mice. In addition, there are several other rodent models which do not involve transplantation technology that share some (but not all) features in common with psoriasis. This review will summarise these available animal models and critique their relevance with respect to illuminating the immunogenetic basis of psoriasis and their value in screening novel treatments in a preclinical setting.

How frequent is altered gene expression among susceptibility genes to human complex disorders?

It is regularly thought that human complex disorder susceptibility genes show differences in gene expression between normal and pathologic tissues. Thus, differences of transcript amounts could be indicative of complex disorder susceptibility loci and, therefore, be used for the discovery or the validation of human susceptibility genes to complex disorders/traits. Whether human complex disorder susceptibility genes effectively display differences in transcript amounts was tested by meta-analysis of the published literature comparing transcript amounts of well-validated human susceptibility genes to complex traits/disorders. A total of 94 gene-disease associations, which were studied in at least three independent studies and showed strong evidence of positive association, were analyzed. For 23 out of these 94 well-validated gene-disease associations, 120 gene expression studies comparing normal and pathologic human tissues were found. For 60 out of these 120 gene expression studies, the difference of level expression between normal and pathologic human tissues was statistically significant. This result was highly significant, as only 6 significant results were expected randomly under the null hypothesis (P < 10(-112)). A large excess of replication studies were also found, which were in agreement with the original report (P = 6 x 10(-4)). However, the overall level of expression change between normal and pathologic human tissues was relatively moderate, because only 36 (60%) and 19 (31.6%) out of the 62 statistically significant gene expression studies reached 2- or 3-fold changes in expression level, respectively. The present meta-analysis confirms statistical differences of expression levels between normal and pathologic human tissues for human susceptibility genes to complex traits/disorders. However, the levels of differences in transcript amounts appear to be relatively weak. These findings rationalize the use of gene expression for the discovery/validation of human susceptibility genes, but the weak differences of expression typically found should be taken into account for the design of such studies.

Seronegative spondyloarthropathies: to lump or split?

The advent of novel biological therapies for the treatment of rheumatic disease has renewed interest in the seronegative spondyloarthropathies (SpAs). International efforts are redefining disease classification and measures of disease activity, outcome, metrology, and imaging. However, opinion is divided between those who propose that the SpA group represents the same disease with variable expression (the "lumpers") and those who consider these to be separate diseases with shared clinical features (the "splitters"). This review presents the evidence for both approaches.

Etanercept in psoriasis

Psoriasis is a chronic skin disorder that affects approximately 2% of the US and European populations. Several lines of evidence have demonstrated the correlation between elevated levels of TNF and psoriasis, suggesting that interfering with the inflammatory effects of TNF may help resolve psoriatic lesions. The biological agent, etanercept, is a fully human soluble TNF-receptor fusion protein with proven efficacy in the treatment of rheumatoid arthritis, ankylosing spondylitis, juvenile rheumatoid arthritis, and psoriatic arthritis. In several well-controlled clinical trials, etanercept showed sustained efficacy in reducing the signs and symptoms of psoriasis in patients with moderate-to-severe disease. With the exception of injection site reactions, adverse event rates were similar to placebo and did not increase across higher doses. No opportunistic infections, including tuberculosis, were reported. From analysis of the available clinical trials, etanercept appears to be an effective and well-tolerated agent for the treatment of moderate-to-severe psoriasis.

Psoriasis: emerging therapeutic strategies

Psoriasis is a chronic inflammatory skin disorder that is characterized by thickened, scaly plaques, and is estimated to affect approximately 1-3% of the Caucasian population. Traditional treatments, although effective in patients with limited disease, have numerous shortcomings, including inconvenience and toxicity. These drawbacks mean that many patients experience cycles of disease clearance, in which normal quality of life alternates with active disease and poor quality of life. However, as this review discusses, recent advances have highlighted the key role of the immune system in the pathogenesis of psoriasis, and have provided new defined targets for therapeutic intervention, offering hope for safe and effective psoriasis treatment.

Sustained benefits of infliximab therapy for dermatologic and articular manifestations of psoriatic arthritis: Results from the infliximab multinational psoriatic arthritis controlled trial (IMPACT)

OBJECTIVE

To investigate the efficacy and tolerability of infliximab therapy for the articular and dermatologic manifestations of active psoriatic arthritis (PsA).

METHODS

One hundred four patients with PsA in whom prior therapy with at least 1 disease-modifying antirheumatic drug (DMARD) had failed were recruited into this investigator-initiated, multicenter, randomized, double-blind, placebo-controlled clinical trial. During the initial blinded portion of the study, patients received infusions of infliximab (5 mg/kg) or placebo at weeks 0, 2, 6, and 14. After week 16, patients initially assigned to receive placebo crossed over to receive infliximab 5 mg/kg every 8 weeks through week 50, while patients initially randomized to infliximab continued to receive active treatment at the same dose through week 50. The primary efficacy outcome was achievement of the American College of Rheumatology 20% criteria for improvement in rheumatoid arthritis (ACR20) at week 16. Additional predefined clinical efficacy assessments included the Psoriasis Area and Severity Index (PASI) score, the ACR50 and ACR70 criteria, the Disease Activity Score in 28 joints, the Health Assessment Questionnaire, ratings of enthesitis and dactylitis, and the Psoriatic Arthritis Response Criteria score.

RESULTS

The proportion of infliximab-treated patients who achieved an ACR20 response at week 16 (65%) was significantly higher than the proportion of placebo-treated patients who achieved this response (10%). In addition, 46% of infliximab-treated patients achieved an ACR50 response, and 29% achieved an ACR70 response; no placebo-treated patient achieved these end points. Among patients who had PASI scores of >/=2.5 at baseline, 68% of infliximab-treated patients achieved improvement of >/=75% in the PASI score at week 16 compared with none of the placebo-treated patients. Continued therapy with infliximab resulted in sustained improvement in articular and dermatologic manifestations of PsA through week 50. The incidence of adverse events was similar between the treatment groups.

CONCLUSION

Therapy with infliximab at a dose of 5 mg/kg significantly improved the signs and symptoms of arthritis, psoriasis, dactylitis, and enthesitis in patients with active PsA that had been resistant to DMARD therapy. With continued infliximab treatment, benefits were sustained through 50 weeks. The benefit-to-risk ratio appeared favorable in this study population.

Psoriasis: A complex clinical and genetic disorder

Psoriasis is associated with arthritis in approximately 10% of patients. The skin disease and arthritis have a strong but complex genetic component. Several susceptibility loci have been reported including one major locus that maps very close to the human leukocyte antigen-C gene on chromosome 6p. No causative gene has so far been conclusively identified. A recent genetic analysis that only included patients with psoriatic arthritis revealed a highly significant susceptibility locus on chromosome 16q approximately 20 cM from the NOD2 gene that has been associated with Crohn's disease. This locus was barely detectable when the entire cohort of psoriasis patients was analyzed as a homogeneous entity. A further clinical stratification of psoriasis patients has revealed novel strongly suggestive loci and also increased the logarithm of the odds scores of some previously reported loci. It is concluded that a careful documentation of clinical features and phenotypic stratification may help to analyze complex genetic disorders.

Genetic polymorphisms of the HCR gene and a genomic segment in close proximity to HLA-C are associated with patients with psoriasis in Taiwan

BACKGROUND

Although psoriasis vulgaris (PV) is strongly associated with HLA-Cw*0602, it has been proposed that the association of Cw*0602 is due to linkage disequilibrium and that other nearby genes are involved in PV susceptibility. The alpha-helix coiled-coil rod homologue (HCR) gene, located 110 kb telomeric to the HLA-C locus, is presumed to be one of the PV candidate genes. Recently, a 10-kb genomic segment, centromeric to HLA-C, defined by two new single nucleotide polymorphisms (SNPs) n.7*A and n.9*C, was found to have a stronger association with psoriasis than the HCR gene. Until now, no study of the association of the HCR gene, SNPs n.7, and n.9 has been conducted on Chinese patients with psoriasis.

OBJECTIVES

We aimed to determine whether the genetic polymorphisms of the HCR gene, SNPs n.7*A, and n.9*C were associated with an increased risk of psoriasis in Chinese patients.

METHODS

Using direct sequencing of the HCR gene and the genomic region containing SNPs n.7 and n.9, we investigated the HCR gene, SNPs n.7, and n.9 for disease association in 115 Chinese patients with psoriasis and 103 control subjects. The HCR SNPs were confirmed by denaturing high performance liquid chromatography. Genotyping for HLA-Cw*0602 was also carried out using sequence-based typing.

RESULTS

We observed a different allelic distribution between patient and control groups at nucleotide positions 386, 404, 1802 and 2406 of the HCR gene, and SNPs n.7, and n.9. The associations were much stronger in early onset PV patients (for HCR-386*T and HCR-404*T, odds ratio = 5.63, Pc < 0.0001). The HLA-Cw*0602 also displayed a similar association with PV (odds ratio = 5.4, Pc < 0.0001). Moreover, SNP n.7*A, SNP n.9*C, Cw*0602, HCR-386*T, HCR-404*T and HCR-1802*T were in linkage disequilibrium with each other. Haplotype-based association analysis showed SNP n.7*A-SNP n.9*C-Cw*0602-HCR-386*T-HCR-404*T-HCR-1802*T-HCR-2406*G as a major susceptibility haplotype in this Chinese population (for early onset patients, odds ratio = 5.15, Pc < 0.0001).

CONCLUSIONS

Our results indicate that the HCR gene, SNP n.7*A, and SNP n.9*C as well as Cw*0602 are major susceptibility markers for psoriasis in Chinese patients.

The MICA-A4 triplet repeats polymorphism in the transmembrane region confers additional risk for development of psoriatic arthritis in the Croatian population

The aim of this study was to investigate possible differences in the frequencies of alleles at the HLA loci and at microsatellite loci within the HLA region among patients suffering from psoriatic arthritis (PsA) and healthy controls. Fifty-eight Croatian PsA patients (28 male and 30 female) and 157 healthy unrelated controls were typed for HLA alleles (A, B, Cw and DRB1) by the polymerase chain reaction-sequence-specific primers (PCR-SSP) method, while microsatellite alleles (D6S265, D6S273, MHC class I chain-related gene (MICA) and MIB) were analysed by electrophoresis in an ALFexpress sequencer (Pharmacia Biotech, Uppsala, Sweden). The findings from this study were: (1) the frequencies of B*39 and B*57 were significantly increased in PsA patients; (2) differences in the frequencies of B*13 and B*27 were not statistically significant after correction; (3) the B*0702, B*18, and B*38 alleles were decreased in patients only before correction; (4) none of the alleles at other HLA loci tested were associated with PsA in Croatia; (5) polymorphism at D6S265, D6S273, and MIB microsatellites in patients did not show any statistically significant differences when compared to controls; (6) the increase in the MICA-A4 allele frequency in PsA patients was independent of the B*39 and B*57 alleles.

Lack of Association between the Promoter Polymorphisms at Positions –308 and –238 of the Tumor Necrosis Factor Alpha Gene and Psoriasis vulgaris in Japanese Patients

BACKGROUND

Psoriasis features an increased level and activity of tumor necrosis factor alpha (TNF-alpha). The TNF-alpha gene has single nucleotide polymorphisms (SNPs) at positions -308 (-308G>A) and -238 (-238G>A) in the promoter region, and the -238G>A SNP has been reported to be associated with psoriasis vulgaris (PV) and psoriatic arthritis in Caucasians.

OBJECTIVE

To examine whether these SNPs are associated with susceptibility to PV in Japanese patients, we investigated the genotype and allele frequencies at each SNP in Japanese PV patients and in controls.

METHODS

We examined 163 PV patients and 96 healthy individuals. Genotyping was performed using the polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

No significant association between the genotypes or alleles of these SNPs and susceptibility to PV was observed.

CONCLUSION

These SNPs themselves are not associated with susceptibility to PV in the Japanese.

Polymorphisms in the +252(A/G) lymphotoxin-alpha and the -308(A/G) tumor necrosis factor-alpha genes and susceptibility to chronic periodontitis in a Czech population

BACKGROUND

Periodontitis is an inflammatory disease that leads to irreversible attachment loss, bone destruction and eventually tooth loss. Tumor necrosis factor (TNF), a pluripotent proinflammatory cytokine that is able to induce tissue destruction and bone resorption, has been implicated in the pathogenesis of periodontal disease.

METHODS

In this study, we investigated an association between chronic periodontitis and two previously described bi-allelic polymorphisms in the TNF locus: a G to A transition at position -308 in the 5'promoter region of the TNF-alpha gene and an NcoI restriction fragment length polymorphism (RFLP) in the first intron (position +252A/G) of the lymphotoxin alpha (LT-alpha) gene. Genomic DNA was obtained from 132 patients with chronic periodontitis together with 114 age- and gender-matched unrelated control subjects.

RESULTS

The TNF-alpha (-308G/A) polymorphism itself showed no association with chronic periodontitis, whereas the frequency distribution of the LT-alpha (+252A/G) genotypes showed statistically significant differences between patients and the reference group. The proportion of individuals carrying the LT-alpha 1/1 genotype was significantly lower in the group of patients with chronic periodontitis (0.8%) than in the control group (8.8%) (P < 0.0094, Pcorr < 0.05). However, the significant differences in the frequencies of the combined genotypes (TNF-alpha and LT-alpha) between the control and the patient groups were found using a simulation by applying the Monte-Carlo method (P < 0.01).

CONCLUSION

Our data suggest that combined genotypes composed of the TNF-alpha and LT-alpha gene polymorphisms may influence the susceptibility to chronic periodontitis. We also showed that, comparing the two genes, the 1/1 genotype of the NcoI polymorphism in the first intron of the LT-alpha gene is a more informative marker and it may be one of the protective genetic factors against chronic periodontitis in our population.

Cytokine gene polymorphisms in atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) and psoriasis are genetically determined inflammatory skin disorders characterized by abnormal cytokine production. From association studies there is evidence that functionally relevant cytokine gene polymorphisms contribute to the genetic basis of psoriasis. Association studies in AD have mostly been limited to polymorphisms of T-helper 2-type cytokines, which dominate in acute AD lesions. Unexpectedly, the results of recent genome scans indicate linkage of AD to psoriasis susceptibility loci. Therefore, AD may also be influenced by genes that modulate cutaneous inflammation independently from atopic mechanisms.

OBJECTIVES

To investigate further the role of cytokine gene polymorphisms in AD.

METHODS

Polymorphisms in the genes encoding tumour necrosis factor-alpha (TNFA-238 G/A, -308 G/A), interleukin (IL)-1beta (IL1B-511 T/C, +3953 T/C), IL-6 (IL6-174 C/G), IL-10 (IL10-1082 A/G) and the IL-1 receptor antagonist (IL1RN intron 2) were investigated in German patients with AD (n = 94) and in healthy nonatopic individuals (n = 214) by polymerase chain reaction-based methods and direct cycle sequencing.

RESULTS

No association was found between AD and any of the polymorphisms analysed. This is in contrast to the recently described association between psoriasis and the TNFA-238 and IL1B-511 polymorphisms.

CONCLUSIONS

Our data indicate that cytokine gene polymorphisms may act as specific markers of inflammatory skin diseases rather than contribute to a general disposition towards cutaneous inflammation.

Connections between psoriasis and Crohn's disease

The prevalence of psoriasis in patients with Crohn's disease (CD) is higher than chance would allow if they were mutually exclusive diseases. A close examination reveals genetic and pathologic connections between these diseases. An appreciation for the role of tumor necrosis factor-alpha in both diseases has proven very important. Increased levels of this inflammatory cytokine have been measured in CD lesions, and in 1997 a clinical trial demonstrated the response of this disease to infliximab, a monoclonal antibody specific for tumor necrosis factor-alpha. A subsequent clinical trial evaluated infliximab in a patient with CD and psoriasis, another disease in which increased levels of tumor necrosis factor-alpha are seen in lesions. Scientists noticed the marked skin improvement of this patient and later demonstrated the efficacy of infliximab for psoriasis in a randomized, double-blind, placebo-controlled trial. Thus, an appreciation for connections between psoriasis and CD can suggest novel therapeutic strategies with ensuing benefits to patients. This article reviews epidemiologic, genetic, and pathologic connections between psoriasis and CD and discusses pharmaceuticals targeting inflammatory mediators common to each disease. (J Am Acad Dermatol 2003;48:805-21.)

LEARNING OBJECTIVE

At the completion of this learning activity, participants should understand how psoriasis and Crohn's disease are related at epidemiologic, genetic, and pathological levels and should appreciate how to use this knowledge to treat these diseases.

Advances in understanding the genetic basis of rheumatoid arthritis and osteoarthritis: implications for therapy

Rheumatoid arthritis (RA) and osteoarthritis (OA) are polygenic diseases. Polymorphisms in candidate genes have been studied for possible association with susceptibility to disease development. Aside from HLA polymorphisms, of particular interest are those in genes encoding cytokines, signaling molecules, and enzymes involved in the production and catabolism of oxygen and nitrogen radicals. Cytokines are involved in the modulation of the pathological process and have been the target for novel therapeutic interventions. Evidence for their involvement in RA and OA has been provided from genetic analyses in patient populations as well as from animal models of disease. Intracellular signaling cascades control cellular responses and thus regulate many aspects of the pathology manifested in rheumatic diseases. Deciphering the organization and activity of such signaling pathways in disease is underway. Polymorphisms have been identified in gene promoter regions regulating efficient binding of transcription factors, and in coding regions of genes whose products are involved in signal cascades relevant to RA. Among these are the NF-kappaB pathway, steroid receptors and the p53 tumor suppressor gene. Both reactive oxygen species (ROS) and reactive nitrogen species (RNS) have also been implicated in rheumatic diseases. It is thought that excess, damaging, ROS/RNS may arise from an imbalance between the production and removal of these chemical species. Polymorphisms in genes that encode enzymes involved in either generating or degrading ROS/RNS may contribute to such an imbalance. In the last few years, polymorphisms in such genes have indeed been identified as risk factors for rheumatic diseases.

Polymorphisms of tumor necrosis factor (TNF) alpha and beta genes in Korean patients with psoriasis

To evaluate the association of TNF-alpha (TNFA) and TNF-beta (TNFB) polymorphisms with psoriasis in the Korean population, we investigated TNF-alpha -238 and -308 promoter region and TNF-beta NcoI polymorphism using PCR-RFLP in 103 Korean psoriasis patients and 125 normal controls. The carriage and allele frequencies of TNFB*2 were significantly increased in patients with psoriasis compared with normal controls. However, TNFB*1/1 homozygote and TNFB*1 allele were significantly decreased in the patients. There were no significant differences in the polymorphism of TNF-alpha promoter -238 and -308 between the patients and controls. We also analyzed the frequencies of TNFB alleles according to the clinical characteristics of the psoriasis patients, but no significant differences were found. However, female patients with early-onset psoriasis showed an association with the TNFB*2 allele. In conclusion, our results suggest that polymorphisms of the TNFB gene may contribute to a predisposition to psoriasis in the Korean population.

A study of candidate genes for psoriasis near HLA-C in Chinese patients with psoriasis

BACKGROUND

Genetic analyses have identified the HLA-Cw6 allele as the major risk allele for psoriasis in many racial groups. However, by serological typing, HLA-Cw6 is not considered a risk factor in Chinese psoriatics. There are several susceptibility genes for psoriasis residing in chromosome 6p near the HLA-C locus, including the corneodesmosin (CDSN) gene, the octamer transcription factor-3 (POU5F1) gene, the major histocompatibility complex class I chain-related gene A (MICA), and the gene for tumour necrosis factor (TNF)-alpha. However, the information about their role in psoriasis in Chinese patients is limited.

OBJECTIVES

We aimed to determine whether Cw6 and the genetic polymorphism of the CDSN gene, POU5F1 gene, MICA gene and the gene for TNF-alpha promoter region were associated with an increased risk of psoriasis in Chinese patients.

METHODS

We conducted a case-control association study in 105 Chinese patients with psoriasis vulgaris and 160 control subjects of similar ages. Genotypes of Cw6, the CDSN gene, the POU5F1 gene, and the gene for the TNF-alpha promoter region were determined by polymerase chain reaction (PCR) followed by restriction enzyme digestion. Genotyping of MICA was determined by PCR combined with fluorescent-based automated fragment detection technology. Results The allele frequencies showed no differences between patients and controls for the POU5F1 gene, MICA gene and the gene for TNF-alpha promoter region. The frequency of the HLA-Cw6 allele in the psoriasis group was significantly higher than that in the control group (18.6% vs. 6.56%, P < 0.00005). For the CDSN gene, patients were more likely to have C allele at position +619 (P = 0.006) and C allele at position +1243 (P = 0.007), but the significance disappeared after correction for multiple testing (Pc > 0.05).

CONCLUSIONS

HLA-Cw6 remains the most significant susceptibility gene in Chinese patients with psoriasis. However, the role of the CDSN gene in the pathogenesis of psoriasis deserves further scrutiny.

Cytokine gene polymorphisms in allergic contact dermatitis

Susceptibility to contact allergy may be influenced by genetically determined alterations in the production of pro- and anti-inflammatory cytokines. This report focuses on functional polymorphisms in the genes encoding for several cytokines involved in the pathogenesis of contact allergic responses, including tumour necrosis factor (TNF)-alpha (G-238 A, G-308 A), interleukin (IL)-1beta (C-511G, T+ 3953C), its natural antagonist, the IL-1 receptor antagonist (VNTR intron 2), and IL-6 (G-174C). Polymorphisms were investigated by PCR techniques among polysensitized individuals, defined as individuals with confirmed contact sensitization to para-substituted aryl compounds and at least one other structurally unrelated allergen (n = 86), and healthy control individuals without a history of eczema (n = 310). The distribution of TNFA-308 genotypes was significantly different in these groups (Padjusted= 0.0378). Compared with carriers of 2 wild-type alleles (TNFA-308*1/1 (*G/G)), carriers of the TNFA-308*1/2 (*G/A) and TNFA-308*2/2 (*A/A) genotypes tended to be more common among polysensitized individuals [OR = 1.54, 95% CI (0.92-2.55) and OR = 2.36 (0.84-6.51), respectively]. No significantly different distribution of genotypes was detected at any other polymorphic loci among control individuals without eczema and polysensitized subjects. These findings suggest a possible relationship between the TNFA-308 polymorphism and contact allergy. The results need to be confirmed in future studies.

Involvement of NF-kappaB signalling in skin physiology and disease

Transcription factors of the nuclear factor-kappaB (NF-kappaB)/Rel family play a crucial role in gene regulation during a variety of different cellular processes. This review focuses on the increasing knowledge of the role of NF-kappaB in skin physiology and pathology. Several studies demonstrate that NF-kappaB, or components of the system such as IkappaB kinase (IKK)-alpha, seem to be involved in epidermal development and differentiation. Furthermore, a dysregulation of NF-kappaB is suggested to play an important role in skin pathology, including proliferative disorders, e.g. psoriasis, inflammatory processes such as incontinentia pigmenti (IP), sunburn, Lyme disease, allergic contact dermatitis and autoimmune diseases, as well as also in skin carcinogenesis. However, although the knowledge concerning the role of NF-kappaB in the homeostasis of the skin is steadily increasing, many more questions need to be answered.

Interleukin-12 p40 gene (IL12B) 3'-untranslated region polymorphism is associated with susceptibility to atopic dermatitis and psoriasis vulgaris

Interleukin-12 (IL-12) is believed to play an important role in inducing Th1-type cytokine profiles. Atopic dermatitis (AD) and psoriasis vulgaris (PsV) are considered to be Th2 and Th1 type disease, respectively. The IL-12 p40 subunit gene (IL12B) is located at chromosome 5q31-33 and linkage findings of AD on 5q31 were reported. Recently single nucleotide polymorphism (SNP) (1188A/C) of IL12B has been reported. In function, it has been reported that this SNP is associated with IL12B mRNA expression levels. To learn whether this SNP is associated with susceptibility to AD or PsV, we investigated the genotype and allele frequencies of the SNP in AD patients, in PsV patients and in controls, examining 164 AD patients, 143 PsV patients and 100 healthy individuals in Japanese population. Genotyping was performed using the polymerase chain reaction-restriction fragment length polymorphism method. The A allele was decreased in AD patients (40.9%, p = 0.031) and increased in PsV patients (60.1%, p = 0.035) compared with controls (50.5%). This suggests that IL12B SNP is associated with susceptibility to AD and PsV, presumably by affecting the Th1/Th2 balance.

Open-label study of infliximab treatment for psoriatic arthritis: clinical and magnetic resonance imaging measurements of reduction of inflammation

OBJECTIVE

To evaluate infliximab efficacy and safety in disease-modifying antirheumatic drug-unresponsive psoriatic arthritis (PsA).

METHODS

In a 54-week, open-label, compassionate-use study, 10 patients received intravenous infliximab (5 mg/kg; weeks 0, 2, 6; individualized dosing after week 10). Patients continued their current therapy (stable dose) until week 10. Assessments were performed at weeks 2, 6, 10, and 54. Magnetic resonance imaging (MRI) objectively measured joint inflammation at weeks 0 and 10.

RESULTS

Patients achieved a 20% improvement according to the American College of Rheumatology (ACR) criteria (ACR20) in all patients by week 2; 8 patients improved 70% (ACR70) at week 10; 6 patients maintained ACR70 after week 54. Week 10 MRI revealed an 82.5% mean reduction in inflammation from baseline, and psoriasis area and severity index scores were reduced by 71.3% +/- 16.7%. There were no significant adverse events, severe infections, or infusion reactions.

CONCLUSION

Infliximab was effective, safe, and well tolerated in PsA. Arthritis and psoriasis improved in all patients during the 54-week evaluation. Further investigation of the use of infliximab for PsA and psoriasis is warranted.

Lack of association of TNF-238A and -308A in Japanese patients with psoriasis vulgaris, psoriatic arthritis and generalized pustular psoriasis

Tumor necrosis factor (TNF)-alpha is one of the proinflammatory cytokines and immunomodulators, and has an important pathogenetic role in psoriasis. The TNF-alpha gene (TNFA) is in the human leukocyte antigen (HLA) class III locus on chromosome 6, which might be related to the pathogenesis of psoriasis. It has been suggested that some polymorphisms of the TNFA gene promoter, especially G to A conversions at nt-238 and -308 (TNF-238A and -308A), may be associated with psoriasis in Caucasians. We investigated single nucleotide polymorphisms (SNPs) of the TNFA gene promoter in Japanese psoriasis patients, including 18 with psoriasis vulgaris (PsV), 11 with psoriatic arthritis (PsA), two with generalized pustular psoriasis (GPP), and six with GPP with arthritis. The DNA fragment of the TNFA gene from nt-400 to -69 was amplified by polymerase chain reaction (PCR) and the products were sequenced. Although TNF-238A and other polymorphisms were not found in PsV and psoriatic arthritis patients, one male patient with GPP and PsA had TNF-308A. This suggests that TNFA gene promoter polymorphism in the region examined is less associated with the pathogenesis of psoriasis in Japanese patients, however there might be the possibility that TNFA gene promoter polymorphism is associated with GPP. Further investigation will be required to prove this.

Treatment of psoriasis with the chimeric monoclonal antibody against tumor necrosis factor alpha, infliximab

BACKGROUND

Psoriatic skin lesions in patients with Crohn's disease or psoriatic arthritis have shown improvement during infliximab treatment.

OBJECTIVE

The purpose of our study was to systematically assess the effects of infliximab in patients with psoriatic skin lesions.

METHODS

Eight patients with severe psoriasis were enrolled in an open-label clinical trial. Patients received infliximab, 5 mg/kg, intravenously at weeks 0, 2, and 6. The Psoriasis Area and Severity Index (PASI) was used to monitor disease activity at weeks 0, 2, 4, 6, 8, 10, and 14. Week 10 was the end point of the treatment phase; week 14 was the follow-up end point. Pruritus was assessed on a scale of 0 to 3. Histologic sections were prepared from biopsy specimens of uninvolved skin and of psoriatic lesions at weeks 0, 1, and 10 to measure epidermal thickness with the use of a microscopic micrometer grid.

RESULTS

The PASI diminished from 21.8 +/- 4.2 (mean +/- SE) at week 0 to 3.4 +/- 2.0 at week 10, corresponding to 10.7% +/- 4.3% of the original values (100%); on follow-up at week 14, the PASI was 7.1 +/- 2.7 (or still 33.3% +/- 11.3% of the values at week 0). Pruritus decreased from 2.5 +/- 0.26 at week 0 to 0.43 +/- 0.2 at week 10 and to 0.83 +/- 11.3 at week 14. Likewise, epidermal thickness (acanthosis) tended to normalize from 0.41 +/- 0.06 mm at week 0 to 0.14 +/- 0.02 mm at week 10. No adverse effects other than fatigue during infusion on some occasions were reported.

CONCLUSION

Although psoriasis tends to recur beyond 2 months of the infusions, this open study provides evidence that infliximab is an effective treatment.

Epidemiology of psoriatic arthritis

Research into psoriatic arthritis continues to be hampered by the lack of a validated case-definition. There may be progress toward consensus with a new data-derived diagnostic classification criteria set recently reported and a current international project aiming to firmly validate criteria. Statistical techniques such as latent class analysis may permit a comparison of the accuracy of competing criteria sets, in the absence of a gold standard for diagnosis. Genetic studies are inconclusive, but ethnic differences in disease expression suggest a definite genetic role. Recent community-based research suggests an incidence rate of about 6/100,000 per annum, and a prevalence of about 1/1000. Clinic-based disease may be associated with increased mortality, whereas community based disease is not. The development of internationally accepted criteria for the diagnosis of psoriatic arthritis will be a major impetus towards research into this complex disease.

Differential association of polymorphisms in the TNFalpha region with psoriatic arthritis but not psoriasis

OBJECTIVE

To investigate the potential association of tumour necrosis factor alpha (TNFalpha) microsatellite and promoter alleles with psoriatic arthritis (PsA).

METHODS

DNA from 89 white patients with PsA, 65 patients with psoriasis, and 99 healthy white controls was investigated for two TNFalpha promoter (-238 and -308) and three microsatellite polymorphisms (TNFa, c, and d). Patients had previously been studied by serology for HLA class I antigens and by sequence-specific polymerase chain reaction for DRB1* alleles. In addition, TNFalpha production of Ficoll separated peripheral blood mononuclear cells (PBMC) into culture supernatants after stimulation with lipopolysaccharide, alphaCD3 antibodies, phytohaemagglutinin, and streptococcal superantigen C was determined.

RESULTS

A significant, HLA class I independent increase of the TNFa6c1d3 haplotype was found in the group with PsA but not among patients with psoriasis (32% v. 8%, pc<0.008; relative risk (RR)=5.3). In addition, patients with PsA showed a marked decrease of the TNF308A promoter allele (6% v. 18%; pc<0.008; RR=3.5) compared with healthy controls, which was independent of the increased frequency of the -238A polymorphism in this group. PBMC from patients with PsA secreted significantly less TNFalpha than cells from patients without arthritis. In particular, the TNFa6 microsatellite was associated with decreased TNFalpha production.

CONCLUSION

These data indicate that allelic variations at the TNFalpha locus influence susceptibility to PsA. Decreased production of TNFalpha is at least in part genetically determined and might be related to the development of arthritis. However, the association of the TNF308G allele with the disease also points to other disease related haplotypes with still unknown susceptibility genes.

Genetic epidemiology. Psoriatic arthritis

The existence of psoriatic arthritis as a distinct clinical entity remains a topic of debate; some authors propose that it is simply the co-occurrence of psoriasis and inflammatory arthritis. However, a distinct entity is likely to have distinct susceptibility factors in addition to those that contribute to psoriasis and inflammatory arthritis alone. These aetiological factors may be genetic and/or environmental, and in this review, the evidence for distinct psoriatic arthritis genetic susceptibility factors is considered.