About this Research Topic
Spondyloarthritis (SpA) is one of the most common chronic rheumatic diseases, with a prevalence of 0.3% in Western Europe. SpA includes inflammatory joint diseases with various clinical phenotypes such as psoriatic arthritis, reactive arthritis, enteropathic arthritis and ankylosing spondylitis. The latter is frequently associated with extra-articular manifestations, such as uveitis, psoriasis, and inflammatory bowel disease. SpA is known to be associated with the HLA-B27 allele and recognize T cells as key pathogenetic components. In contrast to other rheumatic diseases, SpA affects women and men equally and is not associated with detectable serum autoantibodies. Contrasting rheumatoid arthritis, SpA are additionally responsive to treatment regimens including IL-23 or IL-17-targeting biologics, yet are virtually unresponsive to steroid and MTX treatment. Based on these differences with prototypical autoimmune diseases, such as rheumatoid arthritis or connective tissue diseases, some of the SpA subtypes may be better classified among autoinflammatory diseases, with a predominant innate immunity involvement. The juvenile spondyloarthritis (jSpA) —might be defined as any spondyloarthritis subtype that is diagnosed before the age of 17. It should be noted however that adult and juvenile spondyloarthritis exist on a continuum. In other words, many children diagnosed with a type of juvenile spondyloarthritis will eventually fulfil criteria for adult spondyloarthritis. Furthermore, jSpA often begins as an ‘undifferentiated’ disease, the presentation of which differs in children and adults. Most notably, spinal involvement is uncommon, while hip arthritis is frequently seen in juvenile-onset disease. The ‘undifferentiated’ form under ILAR (The International League of Associations for Rheumatology) classification of juvenile idiopathic arthritis (JIA) is classified as enthesitis-related arthritis (ERA) or psoriatic arthritis.
Advances in the pathogenesis, diagnosis of and management strategies for juvenile SpA will lead to earlier prognosis, development of treatment guidelines and improved rates of inactive disease, which should lead to improved patient outcomes and quality of life. Although the pathogenic mechanisms underlying jSpA are not fully elucidated, several lines of evidence suggest that immune responses mediated by interleukin 17A (IL-17A) are pivotal. Also, genetic and microbiome studies have provided new information regarding possible pathogenesis of jSpA. While recent work suggests that children with JSpA have decreased thresholds for pain in comparison to healthy children however, pain on physical examination and abnormalities on ultrasound of the entheses are not well correlated.
Treatment guidelines for juvenile arthritis, including jSpA, were published by both by PRES and the American College of Rheumatology, and are based on active joint count and presence of sacroiliitis. Newly developed disease activity measures for jSpA include the Juvenile Arthritis Disease Activity Score and the JSpA Disease Activity index. In comparison to other categories of juvenile arthritis, children with JSpA are less likely to attain and sustain inactive disease. Possible differences in the synovial immunopathologic features of jSpA, when compared to adult patients with SpA will be discussed.
Accordingly, in this Research Topic we are interested in original papers as well as review articles that cover following topics of jSpA:
• Terminology and classification
• Epidemiology and etiopathogenesis
• Genetics and genomic studies
• Clinical Presentation
• Laboratory findings
• Imaging findings
• Diagnosis, differential diagnosis and prognosis
Keywords: Juvenile Spondyloarthritis, Juvenile Idiopathic Arthritis, Psoriatic Arthritis, Ankylosing Spondylitis, Autoinflammatory Diseases
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