Susan D. Thompson

Macrophage activation syndrome in patients with systemic juvenile idiopathic arthritis is associated with MUNC13-4 polymorphisms.

OBJECTIVEnSystemic juvenile idiopathic arthritis (JIA) is associated with macrophage activation syndrome. Macrophage activation syndrome bears a close resemblance to familial hemophagocytic lymphohistiocytosis (HLH). The development of familial HLH has been recently associated with mutations in MUNC13-4. The purpose of this study was to assess for possible sequence alterations in MUNC13-4 in patients with systemic JIA/macrophage activation syndrome.nnnMETHODSnThe MUNC13-4 sequence was analyzed in 18 unrelated patients with systemic JIA/macrophage activation syndrome, using 32 primer pair sets designed to amplify the 32 exons and at least 100 basepairs of the adjacent intronic regions. DNA samples obtained from 73 unrelated patients with systemic JIA and no history of macrophage activation syndrome and 229 unrelated healthy individuals were used as controls.nnnRESULTSnThe biallelic sequence variants in MUNC13-4 reported in familial HLH were present in 2 of the 18 patients with JIA/macrophage activation syndrome. Further analysis of the MUNC13-4 sequences revealed an identical combination of 12 single-nucleotide polymorphisms (SNPs) in 9 of the remaining 16 patients with systemic JIA/macrophage activation syndrome (56%). Additional analysis suggested that these 12 SNPs (154[-19] g>a, 261[+26] c>g, 388[+81] g>a, 388[+122] c>t, 570[-60] t>g, 888 G>C, 1389[+36] g>a, 1992[+5] g>a, 2447[+144] c>t, 2599 A>G, 2830[+37] c>g, 3198 A>G) were inherited as an extended haplotype. In several patients, in addition to the described haplotype, there were other SNPs in the second allele of MUNC13-4. Moreover, 1 patient had a complex mutation with 2 changes, 2542 A>C and 2943 G>C, in a cis configuration. The haplotype was present in only 27 (12%) of 229 healthy control subjects (chi(2) = 23.5) and in 6 (8.2%) of 73 patients with systemic JIA and no history of macrophage activation syndrome.nnnCONCLUSIONnThe data suggest an association between MUNC13-4 polymorphisms and macrophage activation syndrome in patients with systemic JIA.

Chemokine Receptor CCR4 on CD4+ T Cells in Juvenile Rheumatoid Arthritis Synovial Fluid Defines a Subset of Cells with Increased IL-4:IFN-γ mRNA Ratios

To understand the mechanisms that promote recruitment and survival of T cells within the pediatric inflamed joint, we have studied the expression of CCR4 and CCR5 on synovial fluid T cells and matched peripheral blood samples from juvenile rheumatoid arthritis (JRA) patients using three-color flow cytometric analysis. Thymus- and activation-regulated chemokine and macrophage-derived chemokine, ligands for CCR4, were measured by ELISA in JRA synovial fluid, JRA plasma, adult rheumatoid arthritis synovial fluid, and normal plasma. IL-4 and IFN-γ mRNA production was assessed in CD4+/CCR4+ and CD4+/CCR4− cell subsets. We found accumulations of both CCR4+ and CCR5+ T cells in JRA synovial fluids and a correlation for increased numbers of CCR4+ T cells in samples collected early in the disease process. Thymus- and activation-regulated chemokine was detected in JRA synovial fluid and plasma samples, but not in adult rheumatoid arthritis synovial fluid or control plasma. Macrophage-derived chemokine was present in all samples. CD4+/CCR4+ synovial lymphocytes produced more IL-4 and less IFN-γ than CD4+/CCR4− cells. These findings suggest that CCR4+ T cells in the JRA joint may function early in disease in an anti-inflammatory capacity through the production of type 2 cytokines and may play a role in determining disease phenotype.