Juvenile psoriatic arthritis and HLA antigens

Psoriatic arthritis in childhood: A commentary on the controversy

Approximately 5% of children with juvenile idiopathic arthritis (JIA) are diagnosed with the psoriatic form of the disease. In recent years, there has been substantial scholarship demonstrating both heterogeneity within the disease as well as similarities with other forms of JIA, culminating in a recent proposal for the categorization of JIA that excluded the psoriatic form altogether. The purpose of the review is to summarize the clinical, epidemiologic, and genetic features of psoriatic JIA (PsJIA), comparing it with other categories of JIA including spondyloarthritis. We conclude that there are sufficient unique clinical and genetic features within PsJIA as well as similarities with its adult counterpart that warrant including it within the JIA paradigm.

The Juvenile Psoriatic Arthritis Cohort in the CARRA Registry: Clinical Characteristics, Classification, and Outcomes

Objective.

Children with clinically diagnosed juvenile psoriatic arthritis (JPsA) who were enrolled in the Childhood Arthritis and Rheumatology Research Alliance (CARRA) registry (CARRA-JPsA) were classified according to pediatric International League of Associations for Rheumatology (ILAR) and adult criteria [Classification criteria for Psoriatic Arthritis (CASPAR)]. Data on demographic and clinical features at baseline and 1-year followup were analyzed and compared.

Methods.

Cross-sectional analysis was performed of CARRA-JPsA patients enrolled between May 2010 and December 2013 and stratified according to age at disease onset (≤ or > 4 yrs). Features of patients fulfilling ILAR and CASPAR criteria were compared at baseline and followup using chi square, Fisher’s exact, Mann-Whitney-McNemar, Wilcoxon signed rank, and t tests, as appropriate.

Results.

Among 361 children enrolled as CARRA-JPsA, 72.02% had symptom onset at > 4 years of age, with a male predominance and high prevalence of enthesitis. At followup, statistically significant improvements were reported in arthritis, dactylitis, enthesitis, psoriasis, sacroiliitis, and nail pitting, but not in health questionnaire (HQ) scores. Of the patients, 80.5% fulfilled ILAR criteria for JPsA. Fifty-two patients, whose disease fulfilled CASPAR criteria but had not been included in the JPsA cohort, manifested more enthesitis, sacroiliitis, inflammatory bowel disease and uveitis and less psoriasis.

Conclusion.

The data support division of patients with JPsA into 2 clinical subgroups, according to age at disease onset. Improvement in objective findings did not correlate with changes in HQ scores. Pediatric rheumatologists currently do not diagnose JPsA in all children whose disease manifestations meet CASPAR criteria. Unification of adult and pediatric PsA classification criteria warrants consideration.

Immunogenetics of juvenile idiopathic arthritis: A comprehensive review

Juvenile idiopathic arthritis (JIA) is the most common chronic inflammatory arthropathy of childhood. Juvenile idiopathic arthritis is believed to be a complex genetic trait influenced by both genetic and environmental factors. Twin and family studies suggest a substantial role for genetic factors in the predisposition to JIA. Describing the genetics is complicated by the heterogeneity of JIA; the International League of Associations for Rheumatology (ILAR) has defined seven categories of JIA based on distinct clinical and laboratory features. Utilizing a variety of techniques including candidate gene studies, the use of genotyping arrays such as Immunochip, and genome wide association studies (GWAS), both human leukocyte antigen (HLA) and non-HLA susceptibility loci associated with JIA have been described. Several of these polymorphisms (e.g. HLA class II, PTPN22, STAT4) are shared with other common autoimmune conditions; other novel polymorphisms that have been identified may be unique to JIA. Associations with oligoarticular and RF-negative polyarticular JIA are the best characterized. A strong association between HLA DRB1:11:03/04 and DRB1:08:01, and a protective effect of DRB1:15:01 have been described. HLA DPB1:02:01 has also been associated with oligoarticular and RF-negative polyarticular JIA. Besides PTPN22, STAT4 and PTPN2 variants, IL2, IL2RA, IL2RB, as well as IL6 and IL6R loci also harbor variants associated with oligoarticular and RF-negative polyarticular JIA. RF-positive polyarticular JIA is associated with many of the shared epitope encoding HLA DRB1 alleles, as well as PTPN22, STAT4 and TNFAIP3 variants. ERA is associated with HLA B27. Most other associations between JIA categories and HLA or non-HLA variants need confirmation. The formation of International Consortia to ascertain and analyze large cohorts of JIA categories, validation of reported findings in independent cohorts, and functional studies will enhance our understanding of the genetic underpinnings of JIA.

Juvenile Psoriatic Arthritis (JPsA): juvenile arthritis with psoriasis?

BACKGROUND

Following the introduction of the ILAR criteria for juvenile idiopathic arthritis, juvenile psoriatic arthritis (JPsA) has become a better recognized category within the inflammatory arthritides of childhood. There are fewer reports describing the characteristics and long-term outcome of patients with JPsA than other subtypes of JIA.The aim of our study was to determine the long-term outcome and clinical course of patients with juvenile psoriatic arthritis (JPsA) and to define subgroups of JPsA.

METHODS

Clinical records of all patients meeting criteria for JPsA were reviewed and divided into 4 groups depending on their clinical features and onset type. Patient characteristics and clinical features at onset and during follow-up were determined.

RESULTS

The cohort consisted of 119 patients: 65 with oligoarticular-onset (55%; persistent 44 and extended 21), 34 (29%) with RF(-) and 4 (3%) RF(+) polyarticular and 16 (13%) enthesitis-related arthritis (ERA). At diagnosis patients with ERA were oldest and more commonly male (p=0.001 and =0.01 respectively). Patients with a polyarticular course had more involvement of small joints of the hands and wrist when compared to patients with persistent oligoarticular and ERA (p<0.001) while patients with ERA had more hip and sacroiliac arthritis (p<0.001 for both). Nail changes were seen in 66 patients (57%) and were associated with DIP involvement (p=0.0034).

OUTCOME

Time to first inactive disease on, but not off, therapy was significantly longer among patients with polyarticular course when compared to oligoarticular and ERA (p=0.016 and p=0.48 respectively). Patients with polyarticular course more frequently had contractures during follow-up than other groups (p=0.01).

CONCLUSION

The long-term outcome of with JPsA was generally good. Patients with JPsA did not appear to form distinct sub-group of patients but rather resembled JIA patients with onset types without psoriasis.

Comparison of patients with juvenile psoriatic arthritis and nonpsoriatic juvenile idiopathic arthritis: how different are they?

OBJECTIVE

To compare the clinical features and outcome between patients with juvenile psoriatic arthritis (JPsA) and non-JPsA juvenile idiopathic arthritis (JIA).

METHODS

Fifty-three children with JPsA, 32 with < 5 joints in the first 6 months of disease (oligo-JPsA) and 21 (> or = 5 joints) polyarticular-onset (poly-JPsA) were compared to 53 patients with JIA who were matched by sex, age, date of diagnosis, and articular onset pattern.

RESULTS

There was no difference in the percentage of patients between the oligoarticular groups who developed extended oligoarthritis or in the percentage of patients who were positive for antinuclear antibodies. The only differences were that 25% of patients with oligo-JPsA had dactylitis compared to 0% of patients with oligo-JIA (p < 0.01) and 50% had nail pitting as compared to 18.7% (p < 0.05). In polyarticular patients the percentages with dactylitis were similar (19% vs 38%; p = 0.25). The frequency of uveitis was identical in the oligoarticular patients but a higher rate was seen in poly-JPsA compared to poly-JIA (23.8% vs 0%; p = 0.02), while contractures were more frequent in poly-JIA compared to poly-JPsA during the course of the illness (47.6% vs 14.3%; p = 0.03) but not at last followup (14.3% vs 4.7%; p = 0.6). At last followup the mean Childhood Health Assessment Questionnaire scores were similar in both the polyarticular and oligoarticular groups.

CONCLUSION

There were only a few differences between patients with JPsA and JIA regarding disease onset, disease course, and outcome. We suggest that large, longterm prospective studies are required to accurately determine whether subdividing JIA according to psoriasis is worthwhile.

Juvenile psoriatic arthritis: longterm outcome and differentiation from other subtypes of juvenile idiopathic arthritis

OBJECTIVE

To compare outcomes in patients with juvenile psoriatic arthritis (PsA) with those in patients with other juvenile idiopathic arthritis (JIA) subtypes, and to evaluate characteristics and genetic markers that may differentiate PsA from other subtypes of JIA.

METHODS

JIA patients first admitted between 1980 and 1985 were clinically examined after a median of 15 years. Health status was reassessed by the Short Form-36 Health Survey (SF-36) after a median of 23 years. Of 336 JIA patients, 31 (9%) had PsA.

RESULTS

Predictors of PsA were psoriasis in the patient (OR 12.06, p = 0.004) or first-degree relative (OR 30.86, p < 0.001), dactylitis (OR 10.97, p < 0.001), and ankle/toe arthritis (OR 3.04, p = 0.038) within the first 6 months. HLA-DRB1*11/12 status (OR 2.69, p = 0.040) and onset after age 6 years (OR 4.41, p = 0.004) differentiated PsA from either oligoarthritis or polyarthritis. After 15 years, PsA patients had poorer physical health than healthy population controls (p = 0.001). After 23 years, the SF-36 physical scores were poorer in PsA patients than in those with either oligoarthritis or polyarthritis (p < 0.045). The need for disease-modifying antirheumatic drugs and/or anti-tumor necrosis factor agents was present in 33% of PsA versus 8% in oligoarthritis and 13% in either oligoarthritis or polyarthritis patients (p < 0.001 and p = 0.002, respectively).

CONCLUSION

In addition to a history of psoriasis, dactylitis, ankle or toe arthritis, and DRB1*11/12 in children with JIA indicate the likelihood of PsA, a subtype associated with unfavorable outcome.

Patients with juvenile psoriatic arthritis comprise two distinct populations

OBJECTIVE

Psoriatic arthritis (PsA) in children is clinically heterogeneous. We examined a large population of children with juvenile PsA for evidence of phenotypic clustering that could suggest the presence of distinct clinical entities.

METHODS

We reviewed the medical records of 139 patients meeting the Vancouver criteria for juvenile PsA. To identify segregation into phenotypic groups, we compared younger patients with their older counterparts and subjected the whole population to 2-step cluster analysis.

RESULTS

Among patients with juvenile PsA, the age at onset is biphasic, with peaks occurring at approximately 2 years of age and again in late childhood. Compared with children ages 5 years and older, younger patients are more likely to be female, exhibit dactylitis and small joint involvement, and express antinuclear antibodies. Progression to polyarticular disease (>or=5 joints) is more common in younger children, although joint involvement remains oligoarticular in the majority of children. In contrast, older patents tend to manifest enthesitis, axial joint disease, and persistent oligoarthritis. Uveitis is equally represented in both age groups. Despite a higher utilization of methotrexate therapy, younger patients required, on average, more than twice as long to achieve clinical remission (23 months versus 9.2 months; P = 0.044). Cluster analysis identified largely overlapping subgroups but suggested that the presence of dactylitis, rather than age, has the greatest capacity to predict essential features of the clinical phenotype.

CONCLUSION

Juvenile PsA comprises 2 distinct populations of patients. Although the pathophysiologic correlate of this finding remains undefined, future studies should avoid the assumption that PsA in childhood constitutes a single etiologic entity.

Spondylarthropathies in children--are they different from those in adults?

Juvenile spondylarthropathies (JSpAs) comprise a group of rheumatic diseases distinct from other categories of juvenile arthritis. Several classification systems have been applied, and some are specific for children, such as the seronegative enthesopathy and arthropathy (SEA) syndrome and the enthesitis-related arthritis, diagnostic forms in the International League of Associations for Rheumatism (ILAR) classification. JSpA seems more frequent than was previously believed, but actual epidemiological data show important variations between studies. Compared to adult patients, children with JSpA present with peripheral arthritis and enthesitis early in disease but sacroiliac and spine joints involvement many years later. A multidisciplinary team in a paediatric environment should be responsible for the management of children with spondylarthropathies to ensure the best care for these children with their chronic disease and risk of long-term disability. Recent advances in the treatment of rheumatic diseases with biological agents show promising results in children with JSpA. Further research needs to be conducted to increase our knowledge of the long-term outcome of these patients, to improve management, and to prevent long-term consequences of the disease.

Pediatric psoriasis and psoriatic arthritis

Psoriasis and psoriatic arthritis (PsA) are not uncommon among the pediatric population. Recognizing and treating these chronic disorders in children present unique challenges for the dermatologist. Paucity of clinical trials and a dearth of available treatment modalities, many of which carry significant risk or adverse effects, can make treating pediatric psoriasis and PsA a daunting task. This review attempts to define and consolidate the current state of knowledge with regards to this disease spectrum. The need for further clinical trials to investigate treatment options in the pediatric population is also discussed.

Evaluation and management of psoriatic arthritis: the role of biologic therapy

Clinicians often view psoriatic arthritis (PsA) as a rather minor arthritic disorder because many are unaware of the substantial damage, disability, and reduced quality of life that patients with this disease can suffer. Compared with better-studied arthritic conditions, such as rheumatoid arthritis (RA) with well-known consequences of disease progression, PsA does not elicit the same urgency to treat early and aggressively. This is largely owing to the lack of predictive epidemiologic data regarding disease progression in PsA. However, numerous studies indicate that PsA and RA are comparable in terms of overall severity of joint involvement and disability over equivalent disease duration. Many of the drugs traditionally used for PsA therapy are also used to treat RA, including nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids, methotrexate (MTX), sulfasalazine, cyclosporine, etretinate, auranofin, intramuscular gold, and azathioprine. All of these drugs have significant risk of toxicity over long-term use, and all provide variable efficacy. This makes it difficult for clinicians to make sound risk-benefit assessments regarding treatment or nontreatment of PsA, because the risks of disease progression cannot be weighed against the risks of therapy. The newer biologic antirheumatic drugs appear to combine greater efficacy of treatment with significantly less toxicity by targeting specific mediators involved in the pathogenesis of PsA.

Juvenile onset spondyloarthropathies: therapeutic aspects

Juvenile onset spondyloarthropathy (SpA) is a term that refers to a group of human leucocyte antigen (HLA)-B27 associated inflammatory disorders affecting children under the age of 16 years, producing a continuum of clinical symptoms through adulthood. This disease is characterised by enthesopathy and arthropathy affecting the joints of the lower extremities and seronegativity for IgM rheumatoid factor and antinuclear antibodies. Children usually present with undifferentiated SpA and progress to differentiated forms over time. Except for the prevalence of some clinical features at onset, the pathogenic and clinical aspects of juvenile onset SpAs resemble those of the adult disease. Thus application of the same or similar therapeutic measures for both juvenile and adult onset SpAs seems logical. Current treatments for juvenile onset SpA provide symptomatic improvement, but do not alter disease progression. The increased expression of tumour necrosis factor alpha (TNFalpha) in synovial tissue of patients with adult and juvenile onset SpA and its correlation with infiltration of inflammatory mediators into the synovia suggest a significant pathogenic role of this cytokine. Clinical trials of anti-TNFalpha antibody (infliximab) therapy in patients with adult onset SpA have demonstrated significant clinical improvement in inflammatory pain, function, disease activity, and quality of life in correlation with histological and immunohistochemical evidence of modulation of synovial inflammatory processes. These promising findings suggest that anti-TNFalpha therapy may confer similar benefits in patients with juvenile onset SpA.

The juvenile-onset spondyloarthritides: rationale for clinical evaluation

This chapter reviews the clinical events that occur in patients with juvenile-onset spondyloarthritides (SpA) with the purpose of developing core sets, domains and instruments to evaluate disease activity and disease damage. We discuss several aspects, from concept and classification to clinical features and instruments already in use for measuring adult-onset SpA and childhood arthritides. Similarly, comparisons between juvenile-onset SpA, its adult counterpart, and other forms of juvenile arthritis are made to consider the adaptation of existing instruments or to develop specific ones.

The juvenile-onset spondyloarthritides

The juvenile-onset spondyloarthritides comprise a group of HLA-B27-associated disorders, which are mainly characterized by enthesitis and arthritis affecting the lower extremities, and in a variable proportion of cases, the sacroiliac and spinal joints. Additional features include a variety of extra-articular manifestations, and in some cases, bacterial infections as triggers. Except for the prevalence of some clinical features at onset and severity throughout the course of the disease, juvenile-onset SpA resemble their adult counterpart in most clinical aspects, strength of HLA-B27 association, and the role of arthritogenic bacteria in their pathogenesis. Not surprisingly, several aspects, from nomenclature to classification, and diagnostic criteria reflect to some extent those developed in the adult onset populations.

Tumour necrosis factor (TNF) in psoriatic arthritis: pathophysiology and treatment with TNF inhibitors

High levels of proinflammatory cytokines, including tumour necrosis factor (TNF), have been detected in psoriatic skin lesions and joints of patients with the inflammatory disease. Early results of treatment of psoriatic arthritis and psoriasis with TNF neutralising agents are encouraging, but whether these agents will be able to improve long term outcomes, such as disability, is not yet known.

Prognostic factors in juvenile idiopathic arthritis

Prognostic factors in juvenile arthritis are related to many variables that must be evaluated according to the different subtypes. The International League of Associations of Rheumatologists (ILAR) recently proposed six different categories referred to as the Durban criteria, under the eponym of juvenile idiopathic arthritis (JIA). The aim of this classification was to define homogeneous groups according to their clinical and biologic features. The prognostic factors were classified into the different categories of JIA. A poor outcome in the systemic form correlated with markers of disease activity, such as fever and polyarticular involvement, within the first 6 months. The risk of joint destruction in oligoarthritis correlated with the severity of arthritis within the first 2 years. Polyarthritis with positive rheumatoid factor is associated with marked disability in adulthood. In a group of psoriatic patients, the risk of developing sacroiliitis is higher in male and HLA-B27-positive patients. Patients with enthesitis-related arthritis with lower limb, knee, and tarsal involvement also are at greater risk of developing sacroiliitis. Chronic uveitis is a complication of JIA observed mainly in patients with oligoarthritis associated with positive antinuclear antibodies in serum. Secondary amyloidosis is observed mainly in children with systemic JIA. The long-term outcome must be discussed according to the various therapies. Corticosteroids contribute to growth retardation and osteoporosis, for which the use of human recombinant growth hormone and biphosphonates may be an option. Newer encouraging therapies such as anticytokines have been proposed for children with active disease. Autologous stem cell transplantation is being evaluated in some centers with promising results; however, it has a high rate of mortality. Further discussion regarding which patients should undergo autologous stem cell transplantation is needed, as is further discussion regarding the technical adaptations necessary.

Joint disease in children of Asiatic origin

Joint disorders in Asian children are varied due to the diversity of the Asian population and show some ethnic trends. The ethnic diversity, socio-economic and geographic factors in Asia have limited the availability of data from some of the ethnic groups, many of whom live in remote and relatively underdeveloped areas, are not subjected to epidemiological surveillance and have little awareness of these diseases and their consequences. Geographic and socio-economic factors also play a significant role in some of the joint diseases peculiar to Asian children. In general, the current available data suggests that there are no large differences in the epidemiology and clinical features between the Western and Asian children. This article reviews the available literature on joint diseases in Asian children.

Spondyloarthropathies in childhood

The concept of spondyloarthropathies in childhood is emerging. It should now be more easily recognized since more specific diagnostic criteria are available for young patients. It probably accounts for about 20% of the whole group of chronic arthritides seen in paediatric rheumatology clinics. Juvenile ankylosing spondylitis stricto sensu is very rare in childhood. Most children who present with peripheral arthritis at onset meet the diagnostic criteria of undifferentiated spondylo-arthropathies such as those of the SEA syndrome, or those of the ESSG or Amor criteria. At follow-up, quite a large proportion of children may develop axial involvement. Psoriatic arthritis differs from the other spondyloarthropathies with a different sex ratio, and an earlier onset. The role of immunogenetic, environmental and ethnic factors are important for a better understanding of these diseases.

Juvenile-onset spondyloarthropathies

This article discusses the clinical spectrum and characteristics of juvenile-onset spondyloarthropathies and includes a review of the demographic, clinical, radiographic (and other imaging techniques), and laboratory data of conditions, syndromes, and diseases making up this group. The pathogenic role of several factors in the context of adult-onset patients, but also in regards to studies already performed in juvenile-onset patients, is discussed.

Spondyloarthropathies of childhood

The term spondyloarthropathy, currently used to describe some forms of idiopathic arthritis of childhood, may be inappropriate because most children included in this category do not have arthritis of the spine, and inflammatory disease of the sacroiliac joints is an infrequent or late finding. Juvenile AS, the archetype, or "complete" disease may account for only one fifth of the so-called "spondyloarthropathies". "Incomplete" or "early" spondyloarthropathies are most frequent. Such children may not develop axial symptoms and signs for 5 to 10 years after onset, and they may be better characterized as having enthesitis-related arthritis, a term proposed by a recent task force of the International League Against Rheumatism (ILAR). Reactive arthritis, although etiologically linked with the spondyloarthropathies, uncommonly progresses to AS in childhood; most patients have peripheral arthritis with or without enthesitis resolving in the relatively short term. The arthritis associated with IBD is more commonly peripheral than axial. Although axial disease undoubtedly occurs in JPsA, in the authors' experience it is very uncommon.

Juvenile psoriatic arthritis

From two studies (Lambert et al, 1976; Shore and Ansell, 1982), it was concluded that juvenile psoriatic arthritis is a distinct entity with one group of patients virtually indistinguishable from those with juvenile chronic arthritis initially, while all the patterns of psoriatic arthritis recorded in adults were seen in the remainder. A family history of psoriasis occurs in about half the patients, and one of arthritis in 20%. A swollen tendon sheath of a single finger or toe associated with synovitis in two or three joints of the digits is highly characteristic. Accurate diagnosis is important because these patients tend to go on to develop an asymmetrical destructive polyarthritis. This needs to be recognized early to utilize effective slow-acting drugs. Southwood and colleagues (1989) have defined two quite distinct groups of juvenile psoriatic arthritis: those young at onset, who are usually girls, and those in adolescence, who are more frequently boys. It is possible that there are other variants, including girls aged 8-10 years with a polyarthritic onset who may go on to develop arthritis mutilans. The concept of 'probable juvenile psoriatic arthritis' is supported by follow-up, in that a significant proportion of such patients do pass into the definite group. It is highly desirable that the suggested Vancouver criteria are validated by a long-term prospective study, which will probably need to be multicentred to ensure that the subgroups are large enough for satisfactory conclusions to be drawn. In the management of this serious arthritis in childhood, it is important to consider long-acting drugs early, before undue damage to joints has occurred. Again, multicentre studies are needed to determine which is the most useful. Presently, methotrexate appears to be the drug of choice.