Use of dynamic magnetic resonance imaging to detect sacroiliitis in HLA-B27 positive and negative children with juvenile arthritides.

OBJECTIVE: Involvement of the sacroiliac (SI) joints is a hallmark of the spondyloarthropathies (SpA), especially, in early and later stages of ankylosing spondylitis in adults. The significance of sacroiliitis in juvenile SpA is less clear and the diagnosis of juvenile SpA is difficult due to the mostly nonspecific or absent history of back pain in children and the time delay associated with the diagnosis of sacroiliitis by conventional radiographs. Our aim was to evaluate dynamic magnetic resonance imaging (MRI) of the SI joints in children and to assess the frequency and the determinants of SI joint involvement in juvenile SpA and other juvenile arthritides. METHODS: Clinical examinations and dynamic MRI were performed in 130 children < 16 years of age with joint complaints, 100 with probable SpA, and 30 controls. The degree of back pain was assessed by a visual analog scale (VAS) (0 = no pain, 10 = very severe pain). The following groups were defined before MRI investigation according to modified European Spondylarthropathy Study Group (ESSG) criteria for SpA: Group 1: undifferentiated SpA (uSpA, n = 41, 88% B27+); Group 2: differentiated SpA (n = 29, 97% B27+), comprising reactive arthritis (n = 16), ankylosing spondylitis (n = 9), psoriatic arthritis (n = 3), and arthritis in inflammatory bowel disease (n = 1); Group 3: patients with no signs of SpA other than oligoarthritis, here named juvenile chronic arthritis (JCA) II (n = 30, 93% B27+); Group 4: HLA-B27+ controls without arthritis (n = 12); and Group 5: HLA-B27-controls with various other non-SpA diagnoses (n = 18). MRI was evaluated according to published criteria allowing for differentiation between acute and chronic changes in SI joints. RESULTS: Acute sacroiliitis without chronic changes could only be detected by dynamic MRI: in 17 patients (11 in Group 1, 3 in Group 2, 3 in Group 3) together in 14/70 (20%) patients with SpA. All these 17 patients had normal pelvic radiographs. Using MRI acute and/or chronic sacroiliitis were found in 35 patients: 17/41 in Group 1 (41%), 15/29 in Group 2 (52%), and 3/30 (10%) patients in Group 3, but in no patients in Groups 4 and 5. Chronic SI joint changes > grade 1 were detected by MRI in 18/70 patients with SpA (25.7%). In comparison, radiographic changes > grade 1 were less often detected in 14/70 patients with SpA (20%) or 23/210 SI joints examined (11 %), compared to 29/210 SI joints found in the MRI examinations (14%) (p = 0.05). Among the 70 patients with SpA, those with MRI diagnosis of acute sacroiliitis had a significantly longer disease duration (62+/-34 vs 28+/-16 months; p = 0.01) and higher C-reactive protein (12+/-12 vs 9+/-14; p = 0.01), and also reported more back pain on VAS (4.3+/-3.6 vs 1.2+/-2.2; p = 0.001) than those without sacroiliitis. CONCLUSION: Dynamic MRI and MRI are useful to detect acute and chronic sacroiliitis in children. The main advantages in comparison with conventional radiographs are the ability to detect acute changes in the SI joints, the higher sensitivity to detect chronic changes, and clearly, the lack of radiation exposure; while the disadvantages are the high costs and the duration of the procedure. Sacroiliitis is fairly common in juvenile SpA and seems to be associated with disease intensity and duration.

Characterization of the synovial T cell response to various recombinant Yersinia antigens in Yersinia enterocolitica-triggered reactive arthritis. Heat-shock protein 60 drives a major immune response.

OBJECTIVE: In Yersinia enterocolitica-triggered reactive arthritis (Yersinia ReA), the synovial T cell response is primarily directed against bacterial components, which are mostly unknown. This study was performed to investigate the synovial proliferative T cell response to a panel of recombinant Yersinia antigens in patients with Yersinia ReA and in controls. METHODS: Synovial fluid mononuclear cells (SFMC) were obtained from 4 patients with Yersinia ReA and from 14 patients with arthritides of different etiology. SFMC were stimulated with 5 recombinant Yersinia antigens (the 19-kd urease beta subunit, 13-kd ribosomal L23 protein, 32-kd ribosomal L2 protein, 18-kd outer membrane protein H, and Y. enterocolitica heat-shock protein 60 [hsp60]), and with human, Chlamydia trachomatis, and Borrelia burgdorferi hsp60. Three T cell clones specific for Y. enterocolitica hsp60 were generated from 1 patient with Yersinia ReA. Antigen-induced cytokine release was measured by enzyme-linked immunosorbent assay. RESULTS: SFMC from all 4 patients with Yersinia ReA responded to each of the Yersinia antigens except the 13-kd protein. These antigens were also recognized by SFMC from a subgroup of patients with undifferentiated arthritis (n = 4), but not by SFMC from other patients with arthritis of different etiology (n = 10). Y. enterocolitica hsp60 induced the strongest proliferative response in all cases. Two types of hsp60-reactive T cell clones could be obtained. One clone responded to all hsp60 variants, including the human variant, and showed a type 2 T helper (Th2)-like cytokine-secretion pattern. In contrast, another clone with specificity for the bacterial hsp60 proteins, but not the human equivalent, reacted with a more Th1-like pattern. CONCLUSION: In Y. enterocolitica-triggered ReA, at least 4 immunodominant T cell antigens exist, which might be used in lymphocyte proliferation assays to identify patients with Yersinia ReA. The hsp60 is a strong antigen, inducing both bacteria-specific and potentially autoreactive CD4+ T cells of both the Th1 and Th2 type.