Arthritis & Rheumatism, Volume 60,
October 2009 Abstract Supplement
The 2009 ACR/ARHP Annual Scientific Meeting
Philadelphia October 16-21, 2009.
Anti-TNF Therapy Leads to Decreased TNF Expression and NF-Kappa-B Signalling in RA Neutrophils
Wright1, Helen L., Chikura2, Batsi, Bucknall2, Roger C., Moots1, Robert J., Edwards1, Steven W.
Neutrophils are the major cell infiltrate in RA synovial fluid and are a source of TNFa, expressing the membrane-bound TNFa precursor protein (mTNF) that becomes active extracellularly upon cleavage. mTNF may also induce signalling via cell-cell contact with TNF receptors on neighbouring cells, and may also reverse-signal via engagement of soluble- or cell-expressed TNF receptors, or anti-TNF drugs. The purpose of this investigation was to investigate the effect of anti-TNF therapy on neutrophils from RA patients.
20 patients with RA were prescribed Etanercept, Adalimumab or Infliximab. Blood was collected before commencement of anti-TNF therapy, and at 4 and 12 weeks after first infusion. Neutrophils were isolated by one-step centrifugation through Polymorphprep, and expression of mTNF was measured by flow cytometry. Protein levels were analysed by Western blot, and mRNA was quantified by real-time PCR. Neutrophils from age-matched controls were also analysed.
80% (16/20) of patients achieved a response to therapy in accordance with EULAR guidelines. Baseline mTNF was significantly higher in RA patients compared to controls, and decreased significantly after 12 weeks therapy (p<0.05). mTNF levels at 4 weeks significantly correlated with 12-week DAS28 (p<0.05, rs=.560). PCR analysis of TNFa mRNA levels showed a significant correlation between the decrease in TNFa mRNA and the decrease in disease activity (DAS28) from baseline to 12 weeks (p<0.05, rs=0.582). Patients achieving low disease activity (DAS28 <=3.2) after 12 weeks showed a significantly greater decrease in TNFa mRNA levels compared to other patients (p<0.05). Patient neutrophils showed significantly increased phosphorylation of NFkB (p65), elevated levels of the anti-apoptotic protein Mcl-1 and lower activation of caspase-9 compared to controls. Expression of caspases-8 and -3 was unchanged by anti-TNF therapy. Neutrophils from patients who achieved low disease activity after 12-weeks showed a significant decrease in NFkB phosphorylation compared to other patients (p<0.05).
Neutrophils from RA patients had an activated phenotype characterised by enhanced NFkB signalling, and levels of proteins which may induce slower rates of constitutive apoptosis. RA neutrophils expressed significantly higher membrane TNFa levels than controls, and mTNF expression following 4-weeks anti-TNF therapy was indicative of 12-week DAS28. Intracellular signalling via NFkB was reduced by anti-TNF therapy in those patients who went on to achieve low disease activity, and these patients also showed a significant decrease in TNFa mRNA production.
To cite this abstract, please use the following information:
Wright, Helen L., Chikura, Batsi, Bucknall, Roger C., Moots, Robert J., Edwards, Steven W.; Anti-TNF Therapy Leads to Decreased TNF Expression and NF-Kappa-B Signalling in RA Neutrophils [abstract]. Arthritis Rheum 2009;60 Suppl 10 :145