Efficacy of etanercept in the tumor necrosis factor receptor-associated periodic syndrome: a prospective, open-label, dose-escalation study.

OBJECTIVE: To investigate the efficacy of etanercept in improving the symptoms and underlying inflammation in patients with tumor necrosis factor receptor-associated periodic syndrome (TRAPS). METHODS: Fifteen patients with TRAPS were enrolled in a prospective, open-label, dose-escalation study. Patients recorded attacks, symptom severity, and use of ancillary medications in a daily diary. Blood samples were collected during each period and measured for levels of acute-phase reactants. Between 7 years and 9 years after the conclusion of the initial study, patients completed a followup survey and were evaluated to determine the long-term outcome of etanercept treatment. RESULTS: Etanercept treatment significantly attenuated the total symptom score and reduced the frequency of symptoms. Etanercept also reduced levels of acute-phase reactants, particularly during asymptomatic periods. During a 10-year followup period, patients continued to receive etanercept for a median of 3.3 years, with a number of patients switching to anti-interleukin-1ß receptor therapy or not receiving biologic agents, most frequently citing injection site reactions and lack of efficacy as reasons for discontinuation. However, patients continuing to receive etanercept had reduced symptoms at followup. CONCLUSION: Etanercept reduces symptoms and serum levels of inflammatory markers of TRAPS in a dose-dependent manner, but does not completely normalize symptoms or acute-phase reactant levels. Although long-term adherence to etanercept is poor, continuing to receive etanercept may provide continued symptomatic benefit.

Abnormal disulfide-linked oligomerization results in ER retention and altered signaling by TNFR1 mutants in TNFR1-associated periodic fever syndrome (TRAPS).

Tumor necrosis factor (TNF) receptor-associated periodic syndrome (TRAPS) is an autosomal dominant systemic autoinflammatory disease associated with heterozygous mutations in TNF receptor 1 (TNFR1). Here we examined the structural and functional alterations caused by 9 distinct TRAPS-associated TNFR1 mutations in transfected cells and a mouse "knock-in" model of TRAPS. We found that these TNFR1 mutants did not generate soluble versions of the receptor, either through membrane cleavage or in exosomes. Mutant receptors did not bind TNF and failed to function as dominant-negative inhibitors of TNFR1-induced apoptosis. Instead, TRAPS mutant TNFR1 formed abnormal disulfide-linked oligomers that failed to interact with wild-type TNFR1 molecules through the preligand assembly domain (PLAD) that normally governs receptor self-association. TRAPS mutant TNFR1 molecules were retained intracellularly and colocalized with endoplasmic reticulum (ER) markers. The capacity of mutant receptors to spontaneously induce both apoptosis and nuclear factor kappaB (NF-kappaB) activity was reduced. In contrast, the R92Q variant of TNFR1 behaved like the wild-type receptor in all of these assays. The inflammatory phenotype of TRAPS may be due to consequences of mutant TNFR1 protein misfolding and ER retention.

Pyrin binds the PSTPIP1/CD2BP1 protein, defining familial Mediterranean fever and PAPA syndrome as disorders in the same pathway.

Pyrin, the familial Mediterranean fever protein, is found in association with the cytoskeleton in myeloid/monocytic cells and modulates IL-1beta processing, NF-kappaB activation, and apoptosis. These effects are mediated in part through cognate interactions with the adaptor protein ASC, which shares an N-terminal motif with pyrin. We sought additional upstream regulators of inflammation by using pyrin as the bait in yeast two-hybrid assays. We now show that proline serine threonine phosphatase-interacting protein [PSTPIP1, or CD2-binding protein 1 (CD2BP1)], a tyrosine-phosphorylated protein involved in cytoskeletal organization, also interacts with pyrin. Recently, PSTPIP1/CD2BP1 mutations were shown to cause the syndrome of pyogenic arthritis, pyoderma gangrenosum, and acne (PAPA), a dominantly inherited autoinflammatory disorder mediated predominantly by granulocytes. Endogenous PSTPIP1/CD2BP1 and pyrin are coexpressed in monocytes and granulocytes and can be coimmunoprecipitated from THP-1 cells. The B box segment of pyrin was necessary and the B box/coiled-coil segment sufficient for this interaction, whereas the SH3 and coiled-coil domains of PSTPIP1/CD2BP1 were both necessary, but neither was sufficient, for pyrin binding. The Y344F PSTPIP1/CD2BP1 mutation, which blocks tyrosine phosphorylation, was associated with a marked reduction in pyrin binding in pervanadate-treated cells. PAPA-associated A230T and E250Q PSTPIP1/CD2BP1 mutations markedly increased pyrin binding as assayed by immunoprecipitation and, relative to WT, these mutants were hyperphosphorylated when coexpressed with c-Abl kinase. Consistent with the hypothesis that these mutations exert a dominant-negative effect on the previously reported activity of pyrin, we found increased IL-1beta production by peripheral blood leukocytes from a clinically active PAPA patient with the A230T PSTPIP1/CD2BP1 mutation and in cell lines transfected with both PAPA-associated mutants.

The expanding spectrum of systemic autoinflammatory disorders and their rheumatic manifestations.

The authors review the genes, and their respective proteins, responsible for eight autoinflammatory conditions. Familial Mediterranean fever is caused by mutations in pyrin, which is the prototype of a new family of proteins belonging to the death-domain superfamily. This new group of proteins, which regulate apoptosis, inflammation, and cytokine processing, share an approximately 90-amino-acid N-terminal sequence called the PYRIN domain. Mutations in another PYRIN domain protein, termed cryopyrin, are responsible for three clinically defined illnesses, Muckle-Wells syndrome, familial cold autoinflammatory syndrome, and NOMID/CINCA. A related protein encoded by the gene is responsible for the Mendelian disorder, Blau syndrome, and also predisposes to Crohn disease. The gene responsible for PAPA syndrome has recently been identified as, and preliminary results from the authors' laboratory also implicate its protein product in these pathways. Lastly, the authors discuss the broadening genetic and clinical spectrum of TRAPS, an autoinflammatory syndrome resulting from mutations in the 55-kDa receptor for tumor necrosis factor.

Monocytic fasciitis: a newly recognized clinical feature of tumor necrosis factor receptor dysfunction.

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS) is a dominantly inherited autoinflammatory syndrome that results from mutations in TNFRSF1A, the gene that encodes the 55-kd tumor necrosis factor receptor. Clinically, patients present with recurrent episodes of fever in conjunction with localized inflammation at various sites. Myalgia is one of the most characteristic features of this syndrome and is frequently associated with an overlying erythematous, macular rash that, together with the myalgia, displays centrifugal migration. This has previously been believed to occur as a result of myositis. We describe herein the case of a 60-year-old man with TRAPS, in whom magnetic resonance imaging of the left thigh demonstrated edematous changes in the muscle compartments and surrounding soft tissues. A full-thickness wedge biopsy was performed, and hematoxylin and eosin staining and immunohistochemistry analysis of the specimen demonstrated normal myofibrils but a severely destructive monocytic fasciitis. These results suggest that the myalgia experienced by individuals with TRAPS is due to a monocytic fasciitis and not to myositis.

The TNF receptor-associated periodic syndrome (TRAPS): emerging concepts of an autoinflammatory disorder.

The present report describes and expands the clinical and genetic spectrum of the autoinflammatory disorder, tumor necrosis factor (TNF) receptor-associated periodic syndrome (TRAPS). A total of 20 mutations have been identified since our initial discovery of 6 missense mutations in TNF receptor super family 1A (TNFRSF1A) in 1999. Eighteen of the mutations result in amino acid substitutions within the first 2 cysteine-rich domains (CRDs) of the extracellular portion of the receptor. A single splicing mutation also affects the first CRD by causing the insertion of 4 amino acids. Haplotype analysis of the most commonly occurring and ethnically heterogeneous mutation, R92Q, demonstrates an ancient founder; however, analysis of the T50M mutation, another commonly occurring mutation in Irish and Scottish families, does not, suggesting that T50M is a recurring mutation. Mutations that result in cysteine substitutions demonstrate a higher penetrance of the clinical phenotype (93% versus 82% for noncysteine residue substitutions), and also increase the probability of developing life-threatening amyloidosis (24% versus 2% for noncysteine residue substitutions). Retrospective and prospective evaluation of more than 50 patients, representing 10 of the 20 known mutations, allows us to expand and better define the clinical spectrum of TRAPS. Recurrent episodes of fever, myalgia, rash, abdominal pain, and conjunctivitis that often last longer than 5 days are the most characteristic clinical features of TRAPS. Defective shedding of TNFRSF1A can only partially explain the pathophysiologic mechanism of TRAPS, since some mutations have normal shedding. Consequently, other mechanisms may be mediating the observed phenotype. We are currently investigating other possible mechanisms using stable and transiently transfected cell systems in vitro, as well as developing a knockin mouse model. Preliminary data suggest that etanercept may be effective in decreasing the severity, duration, and frequency of symptoms in TRAPS patients. Additionally, it provides a viable therapeutic alternative to glucocorticoid therapy, which has numerous serious, long-term adverse effects. Two clinical trials are being conducted to evaluate the efficacy of etanercept in decreasing the frequency and severity of symptoms in TRAPS. Lastly, we have summarized data that R92Q and P46L, and probably as yet undiscovered substitutions, represent very low penetrance mutations that may play a much larger role in more broadly defined inflammatory diseases such as rheumatoid arthritis. Our laboratories are currently undertaking both clinical and basic research studies to define the role of these mutations in more common inflammatory diseases.