Modulation of TNFR 1-triggered two opposing signals for inflammation and apoptosis via RIPK 1 disruption by geldanamycin in rheumatoid arthritis.

OBJECTIVES: To evaluate the ability of geldanamycin to modulate two opposing TNFα/TNFR1-triggered signals for inflammation and cell death. METHODS: The effects of geldanamycin on TNFα-induced proinflammatory cytokine production, apoptosis, NF-κB activation, caspase activation, and necroptosis in a human rheumatoid synovial cell line (MH7A) were evaluated via ELISA/qPCR, flow cytometry, dual-luciferase reporter assay, and western blotting assay, respectively. In addition, therapeutic effects on murine collagen-induced arthritis (CIA) were also evaluated. RESULTS: Geldanamycin disrupted RIPK1 in MH7A, thereby inhibiting TNFα-induced proinflammatory cytokine production and enhancing apoptosis. TNFα-induced NF-κB and MLKL activation was inhibited, whereas caspase 8 activation was enhanced. Recombinant RIPK1 restored the geldanamycin-mediated inhibition of TNFα-induced NF-κB activation. In addition, GM showed more clinical effectiveness than a conventional biologic TNF inhibitor, etanercept, in murine CIA and significantly attenuated synovial hyperplasia, a histopathological hallmark of RA. CONCLUSIONS: GM disrupts RIPK1 and selectively inhibits the TNFR1-triggered NF-κB activation signaling pathway, while enhancing the apoptosis signaling pathway upon TNFα stimulation, thereby redressing the balance between these two opposing signals in a human rheumatoid synovial cell line. Therapeutic targeting RIPK1 may be a novel concept which involves TNF inhibitor acting as a TNFR1-signal modulator and have great potential for a more fundamental, effective, and safer TNF inhibitor. Key Points • Geldanamycin (GM) disrupts RIPK1 and selectively inhibits the TNFR1-triggered NF-κB activation signaling pathway while enhancing the apoptosis signaling pathway upon TNFα stimulation, thereby redressing the balance between these two opposing signals in a human rheumatoid synovial cell line, MH7A. • GM showed more clinical effectiveness than a conventional biologic TNF-inhibitor, etanercept, in murine collagen-induced arthritis (CIA), and significantly attenuated synovial hyperplasia, a histopathological hallmark of RA. • Therapeutic targeting RIPK1 may be a novel concept which involves TNF inhibitor acting as a TNFR1-signal modulator and have great potential for a more fundamental, effective, and safer TNF-inhibitor.

Pathological assessment of the lymph node biopsies for lymphadenopathy in rheumatoid arthritis.

Objectives: To assess the incidence of reactive lymph node hyperplasia (RLH) and the diagnostic characteristics that can help differentiate it from lymphoproliferative disorders (LPD) in patients with rheumatoid arthritis (RA).Methods: Data on patient characteristic from 32 consecutive RA patients with lymphadenopathy at a single medical center over a 6-year period were collected and analyzed to determine whether any of these characteristics can differentiated RLH from LPD.Results: LPD including methotrexate (MTX) - associated LPD (MTX-LPD) and RLH were diagnosed in 19 and 10 patients, respectively. Conclusive diagnosis was not reached in the remaining three cases and they were regarded as grey-zone cases. Age, levels of lactate dehydrogenase (LDH) and soluble interleukin-2 receptor (sIL-2R), as well as maximum standardized uptake value (SUVmax), were significantly higher in LPD than in RLH patients. The diagnosis cut-off values for these parameters were 66 year, 169 U/L, 899 U/mL and 8.18, respectively, based on the receiver operating characteristics curve analysis for both RLH and LPD.Conclusions: About one-third of patients with RA who presented with lymphadenopathy had reactive lymph node enlargement. Older age and higher levels of LDH, sIL-2R, and SUVmax are more associated with LPD than should be considered when deciding to perform a biopsy.

Diffusion-weighted Whole-body Imaging with Background Body Signal Suppression (DWIBS) as a Novel Imaging Modality for Disease Activity Assessment in Takayasu's Arteritis.

A 26-year-old woman with Takayasu's arteritis (TAK) experienced back and neck pain during tocilizumab (TCZ) treatment. The levels of C-reactive protein were normal, and ultrasonography revealed no significant changes. Diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) showed signal enhancement in the walls of several arteries. Contrast computed tomography showed arterial inflammation in the same lesion. After increasing the dose of prednisolone and TCZ, all signal enhancements decreased and continued to decrease, as observed on days 76 and 132. Thus, DWIBS may be a novel imaging modality for assessing the disease activity of TAK, particularly during follow-up.

Crosstalk between tumor necrosis factor-alpha signaling and aryl hydrocarbon receptor signaling in nuclear factor -kappa B activation: A possible molecular mechanism underlying the reduced efficacy of TNF-inhibitors in rheumatoid arthritis by smoking.

OBJECTIVES: To examine the influence of smoking on biologics treatment against different therapeutic targets, such as TNFα, IL-6, and T cell, in rheumatoid arthritis (RA) and elucidate the underlying molecular mechanism. METHODS: The association between drug-discontinuation due to poor therapeutic response and smoking status was analyzed individually in biologics against different therapeutic targets by a multivariable logistic regression analysis using the "NinJa" Registry, one of the largest cohorts of Japanese RA patients. In vitro enhancement of TNFα-induced NF-κB activation and subsequent proinflammatory cytokine production by cigarette chemical components was examined by RT-PCR, qPCR, ELISA, and western blotting using an immortalized rheumatoid synovial cell line, MH7A. RESULTS: The rate of drug-discontinuation due to poor therapeutic response was higher in the current smoking group than in the never- or ever-smoking groups (the odds ratio of current/never smoking: 2.189, 95%CI; 1.305-3.672,P = 0.003; current/ever: 1.580, 95%CI; 0.879-2.839,P = 0.126) in the TNF inhibitor (TNFi) treatment group. However, this tendency was not observed in either the IL-6 or T cell inhibitor treatment groups. Cigarette smoke chemical components, such as benzo[α]pyrene, known as aryl hydrocarbon receptor (AhR) ligands, themselves activated NF-κB and induced proinflammatory cytokines, IL-1ß and IL-6. Furthermore, they also significantly enhanced TNFα-induced NF-κB activation and proinflammatory cytokine production. This enhancement was dominantly inhibited by Bay 11-7082, an NF-κB inhibitor. CONCLUSIONS: These results suggest a crosstalk between TNFα signaling and AhR signaling in NF-κB activation which may constitute one of the molecular mechanisms underlying the higher incidence of drug-discontinuation in RA patients undergoing TNFi treatment with smoking habits.

Sporotrichal Tenosynovitis Diagnosed Helpfully by Musculoskeletal Ultrasonography.

A 72-year-old man presented with persistent oligoarthritis and positive results for rheumatoid factor and was suspected of having rheumatoid arthritis (RA). However, the musculoskeletal ultrasonography (MSUS) findings were not consistent with those of typical RA. He had undergone surgery for carpal tunnel syndrome, which allowed both histopathological and microbiological examinations to be performed. A synovial tissue culture was positive for Sporothrix schenckii, and he was diagnosed with sporotrichal tenosynovitis. He received anti-fungal therapy, and the sporotrichal tenosynovitis resolved. This case suggests that MSUS is a useful modality, and sporotrichal tenosynovitis, though rare, should be considered in the differential diagnosis of RA.