W. Kuis

Mutations in MVK, encoding mevalonate kinase, cause hyperimmunoglobulinaemia D and periodic fever syndrome

Hyperimmunoglobulinaemia D and periodic fever syndrome (HIDS; MIM 260920) is an autosomal recessive disorder characterized by recurrent episodes of fever associated with lymphadenopathy, arthralgia, gastrointestinal dismay and skin rash. Diagnostic hallmark of HIDS is a constitutively elevated level of serum immunoglobulin D (IgD), although patients have been reported with normal IgD levels. To determine the underlying defect in HIDS, we analysed urine of several patients and discovered increased concentrations of mevalonic acid during severe episodes of fever, but not between crises. Subsequent analysis of cells from four unrelated HIDS patients revealed reduced activities of mevalonate kinase (MK; encoded by the gene MVK), a key enzyme of isoprenoid biosynthesis. Sequence analysis of MVK cDNA from the patients identified three different mutations, one of which was common to all patients. Expression of the mutant cDNAs in Escherichia coli showed that all three mutations affect the activity of the encoded proteins. Moreover, immunoblot analysis demonstrated a deficiency of MK protein in patient fibroblasts, indicating a protein-destabilizing effect of the mutations.

Myeloid-related proteins 8 and 14 are specifically secreted during interaction of phagocytes and activated endothelium and are useful markers for monitoring disease activity in pauciarticular-onset juvenile rheumatoid arthritis.

OBJECTIVE To analyze which physiologic stimuli induce secretion of myeloid-related protein 8 (MRP8) and MRP14, two S100 proteins expressed in neutrophils and monocytes, and to determine whether serum concentrations of these proteins are reliable parameters for monitoring inflammatory activity in pauciarticular juvenile rheumatoid arthritis (JRA). METHODS Secretion of MRP8 and MRP14 was analyzed using a coculture system of endothelial cells and monocytes. Concentrations of MRP8/MRP14 in the serum and synovial fluid of JRA patients or culture medium were determined by enzyme-linked immunosorbent assay. The expression of MRP8 and MRP14 by leukocytes in synovial tissue or fluid was investigated using immunohistochemistry. RESULTS MRP8 and MRP14 were specifically released during interaction of activated monocytes with tumor necrosis factor-stimulated endothelial cells. Secretion was mediated via an increase in intracellular calcium levels in monocytes. In contrast, contact with resting endothelium inhibited protein kinase C-induced secretion of the proteins by monocytes. In JRA patients, MRP8 and MRP14 were strongly expressed in infiltrating neutrophils and monocytes within the inflamed joints and could be found in significantly higher concentrations in synovial fluid (mean 42,800 ng/ml) compared with serum (2,060 ng/ml). Concentrations of MRP8/MRP14 in serum correlated well with those in synovial fluid (r = 0.78) and showed a strong correlation with disease activity (r = 0.62). After intraarticular triamcinolone therapy, the serum concentrations of MRP8/MRP14 decreased significantly in therapy responders, whereas no differences were found in patients who showed no clinical benefit. CONCLUSION MRP8 and MRP14 are specifically released during the interaction of monocytes with inflammatory activated endothelium, probably at sites of local inflammation. Their serum concentrations represent a useful marker for monitoring local inflammation in JRA.

Recognition of human 60 kD heat shock protein by mononuclear cells from patients with juvenile chronic arthritis

A postulated mechanism for autoimmune disorders is that the immunoreactivity develops against bacterial antigens which show a high degree of sequence homology with mammalian proteins. The mycobacterial 65 kD heat shock protein (hsp) has been implicated in several forms of arthritis. Substantial amounts of the human 60 kD homologue (hsp60) were produced by insertion of the gene into Escherichia coli. To investigate the hypothesis that T-cell reactivity is directed against the endogenous hsp, T-cell proliferation of synovial-fluid and peripheral-blood mononuclear cells in response to hsp60 was studied in samples from six patients with juvenile chronic arthritis (JCA) and nine adult patients with rheumatoid arthritis (RA). There was no T-lymphocyte proliferative response to purified fractions of hsp60 in mononuclear cells from RA patients or healthy children and young adults. However, both synovial-fluid and peripheral-blood mononuclear cells from JCA patients showed substantial proliferative responses. There was a significant correlation between the stimulation indices for human hsp60 and for mycobacterial hsp65 (r = 0.948, p less than 0.02). A similar correlation for hsp60 and mycobacterial hsp70 did not achieve significance. Immunohistochemistry showed that hsp65 and hsp70 homologues were expressed in the synovial membrane in these patients but not in controls. These findings suggest a sequence of events in which hsps become expressed during synovial inflammation and function as autoantigens. In JCA this may be manifested by specific T-cell reactivity which apparently is lost in the more bone-eroding and non-remitting adult disease.

Juvenile chronic arthritis: T cell reactivity to human HSP60 in patients with a favorable course of arthritis.

Synovial fluid and peripheral blood mononuclear cell proliferative responses to the 60-kD human heat shock protein (HSP60) were studied in 23 patients with juvenile chronic arthritis (JCA) and 7 non-JCA control patients. All patients showed active arthritis at the time of study. The patients were divided into two groups according to the presence (group A) or absence (group B) of T lymphocyte reactivity to human HSP60. We show that reactivity to human HSP60 is primarily, though not exclusively, occurring in patients with a remitting course of disease, i.e., the subgroup of HLA-B27 negative JCA patients with an oligoarticular onset. Immunohistochemical analysis of HSP expression in synovial membranes showed a significantly higher intensity of staining in JCA patients than in non-JCA controls. The results suggest that, in accordance with the earlier observation made in experimental models, T lymphocyte reactivity to human HSP60 in this subgroup of JCA patients may be part of T cell regulatory mechanisms that control the development of arthritis.

Physical activity and health related physical fitness in children with juvenile idiopathic arthritis

Objective: To obtain insight into the interaction between daily physical activity and components of health related physical fitness in children with juvenile idiopathic arthritis. Methods: Forty five patients (10 male/35 female; mean (SD) age 8.9 (2.2) years) participated in the study. Body mass, height, skinfold thickness, number of swollen joints, and joint range of motion were determined. The maximal oxygen consumption (Vo2peak) was assessed during a graded maximal bicycle exercise test. Daily physical activity levels were measured with a Caltrac activity monitor and a parental physical activity rating (PAL) on a five point Likert scale. Results: Partial correlation coefficients (to control for age) between physical activity and indices of health related physical fitness showed significant relationships between Caltrac motion counts and absolute Vo2peak (r=0.31) and relative Vo2peak (r=0.34), but not with the indices of body composition. There was also a significant correlation between PAL and relative Vo2peak (r=0.33). Conclusions: Physical activity was significantly related to cardiorespiratory fitness but not to body composition in children with juvenile idiopathic arthritis. A longitudinal follow up should show whether an active lifestyle protects for loss of aerobic fitness in this patient group.

Antibodies to human HSP60 in patients with juvenile chronic arthritis, diabetes mellitus, and cystic fibrosis.

ABSTRACT: The 60-kD heat shock protein (hsp60) has been implicated in the etiology and pathogenesis of both experimental and naturally occurring autoimmune diseases such as juvenile chronic arthritis (JCA). Human hsp60 is expressed in inflamed synovial tissue, and T lymphocytes both from peripheral blood and synovial fluid show reactivity to human hsp60. Because the anti-hsp60 B lymphocyte response has been less well studied, we have determined the occurrence of IgG anti-human hsp60 antibodies in patients with JCA and various other autoimmune diseases of childhood. Serum IgG anti-human hsp60 antibodies in JCA patients were significantly higher compared with control children (358 and 163 U/mL, respectively). Within the group of JCA patients, the highest antibody titers were found in the subgroup with a polyarticular onset of JCA. IgG anti-human hsp60 antibody levels in synovial fluid were 3− to 4-fold higher compared with paired serum samples. Because this difference was not found for total IgG or for irrelevant antibodies (anti-polyribosylribitol phosphate), this suggests local anti-hsp60 antibody production in the synovial compartment. The occurrence of anti-hsp60 antibodies is not specific for JCA but also is found in children with systemic lupus erythematosus and in cystic fibrosis, whereas mixed connective tissue disease and insulin-dependent diabetes are negative in this respect. Whether the anti-human hsp60 antibodies are directed toward species-specific sequences or to conserved sequences of the hsp60 molecule remains to be determined.

Myeloid related protein 8 and 14 secretion reflects phagocyte activation and correlates with disease activity in juvenile idiopathic arthritis treated with autologous stem cell transplantation

Objectives: To determine whether myeloid related proteins (MRP8/MRP14), a complex of two S100 proteins related to neutrophil and monocyte activation, might be used as a marker for disease activity, and as an early indicator of relapse in juvenile idiopathic arthritis. Patients and methods: A group of 12 patients who underwent an autologous haematopoietic stem cell transplantation (ASCT) for refractory juvenile idiopathic arthritis (JIA) were studied. MRP8/MRP14 serum concentrations were determined by a sandwich enzyme linked immunosorbent assay (ELISA) as described. Improvement from baseline was described by a definition of improvement employing a core set of criteria as detailed previously by Giannini. Results: After ASCT, MRP8/MRP14 serum concentrations in JIA showed a positive correlation with the Child Health Assessment Questionnaire (CHAQ; r=0.80) and erythrocyte sedimentation rate (r=0.45), but not with the total leucocyte count (r=0.26). Mean MRP8/MRP14 serum concentrations dropped markedly in the first three months after ASCT (p=0.0039) and clinical parameters of disease activity such as CHAQ markedly improved (p=0.0039). During a transient relapse there was an increase in MRP8/MRP14. Conclusions: MRP8/MRP14 serum concentration can be used as a marker for disease activity in patients who receive an ASCT for refractory JIA. This indicates a role of macrophage activation in the pathogenesis of JIA. The occurrence of MAS in three patients in this study was not preceded by significant changes in MRP8/MRP14 concentration.

Long-term follow-up of autologous stem cell transplantation for refractory juvenile idiopathic arthritis

Summary:Since 1997, autologous stem cell transplantation (ASCT) had been applied to more than 40 children with polyarticular or systemic juvenile idiopathic arthritis (JIA). For this review, results of the follow-up are available from 25 children with systemic JIA and six with polyarticular JIA that were reported in detail from eight different pediatric European transplant centers. Before ASCT all children had progressive disease despite the use of corticosteroids, methotrexate (MTX) up to 1 mg/kg/week, cyclosporin (2.5 mg/kg/day) and/or anti-TNFα therapy. The clinical follow-up of these children ranges from 8 to 60 months (median 33 months).

Juvenile-onset mixed connective tissue disease : longitudinal follow-up

To establish the symptoms and clinical course of juvenile-onset mixed connective tissue disease, we studied 14 patients, classified according the criteria of Kasukawa et al. The patient records were studied retrospectively and all patients were examined in a 1-day follow-up program. Systemic lupus erythematosus and polymyositis/dermatomyositis-like symptoms disappeared in time, whereas scleroderma-like symptoms (such as in the Raynaud phenomenon) and joint abnormalities persisted. Extensive limitation of joint function was found in four patients. At the time of follow-up, no active renal disease was found. Thrombocytopenia was still present in one of the three patients who had had this feature. All patients had abnormalities of esophageal motility. Long-term corticosteroid treatment was associated with aseptic bone necrosis in three patients and growth retardation in one. We conclude that the Kasukawa criteria are easy to apply to children, and that juvenile-onset mixed connective tissue disease has many similarities to the adult form of the disease.

Hsp60 in inflamed muscle tissue is the target of regulatory autoreactive T cells in patients with juvenile dermatomyositis

OBJECTIVE Juvenile dermatomyositis (DM) is an autoimmune disease of unknown origin characterized by muscle weakness and skin manifestations. No definite autoantigen has yet been identified. Heat-shock proteins (HSPs) can be up-regulated at sites of inflammation, and immune reactivity to Hsp60 is suggested to play a regulatory role in various chronic inflammatory diseases. The purpose of this study was to determine whether Hsp60 could serve as an autoantigen in juvenile DM. METHODS Muscle tissue from 4 patients with juvenile DM and 1 healthy control subject without evidence of muscle disease was stained for Hsp60. Peripheral blood mononuclear cells (PBMCs) from 22 patients and 10 healthy control subjects were tested for T cell proliferation induced by human and microbial Hsp60. Cytokine production in response to Hsp60 was examined in 15 patients and 6 healthy controls. T cell reactivity to Hsp60 was determined in muscle biopsy samples from 2 patients. RESULTS We found significantly increased T cell proliferation to human Hsp60 in PBMCs from juvenile DM patients, which was higher during disease remission. Following in vitro activation with Hsp60, significant amounts of tumor necrosis factor alpha, interleukin-1beta (IL-1beta), and IL-10 were produced. In contrast to muscle biopsy samples from healthy controls, samples from juvenile DM patients showed up-regulation of Hsp60, induction of T cell proliferation, and production of cytokines. Production of proinflammatory cytokines by muscle-derived cells in response to Hsp60 was associated with a poor clinical prognosis, whereas human Hsp60-specific induction of IL-10 was followed by clinical remission. CONCLUSION These findings suggest that human (self) Hsp60 is a disease-relevant autoantigen in juvenile DM. The difference in T cell response with regard to disease activity indicates an immune regulatory effect of Hsp60-specific T cells, opening up perspectives for antigen-specific immunotherapy.