Effects of treatment with a fully human anti-tumour necrosis factor alpha monoclonal antibody on the local and systemic homeostasis of interleukin 1 and TNF alpha in patients with rheumatoid arthritis

Objectives-To study the short term effects of a single dose of D2E7, a full y human anti-tumour necrosis factor (TNF alpha) monoclonal antibody (mAb), on the local and systemic homeostasis of interleukin 1 beta (IL1 beta) and TNF alpha in patients with rheumatoid arthritis (RA). Methods-All patients with RA enrolled in a phase I, single dose, placebo co ntrolled study with D2E7 in our centre were studied. Systemic cytokine leve ls, acute phase reactants, and leucocyte counts were studied at days 0, 1, and 14 after the first administration of anti-TNF mAb (n=39) or placebo (n= 11). The cellularity and the expression of IL1 and TNF alpha in synovial ti ssue were studied in knee biopsy specimens obtained at baseline and at day 14 in 25 consenting patients. Results-A single dose of anti-TNF mAb induced a rapid clinical improvement, a decrease in acute phase reaction, and increased lymphocyte counts in pat ients with active RA. The protein levels of IL1 beta in the circulation wer e low and remained unchanged, but the systemic levels of IL1 beta mRNA (p=0 .002) and the concentrations of IL1 receptor antagonist (IL1ra) and IL6 (p= 0.0001) had already dropped within 24 hours and this persisted up to day 14 . Systemic levels of TNF alpha mRNII were low and remained unchanged, thoug h total TNF alpha (free and bound) in the circulation increased after D2E7, probably reflecting the presence of TNF-antiTNF mAb complexes (p<0.005, at days 1 and 14). Both TNF receptors dropped below baseline levels at day 14 (p<0.005). Despite clinical improvement of arthritis, no consistent immuno histological changes were seen two weeks after anti-TNF administration. End othelial staining for IL1 beta tended to decrease in treated patients (p=0. 05) but not in responders. The staining for IL1 beta and TNF alpha in subli ning layers and vessels was mutually correlated (r(s)=0.47 and 0.58 respect ively, p<0.0005) and the microscopic scores for inflammation correlated wit h sublining TNF<alpha> and IL1 beta scores (r(s)=0.65 and 0.54 respectively , p<0.0001), though none of these showed significant changes during the stu dy. Conclusions-Blocking TNF<alpha> in RA results in down regulation of IL1 bet a mRNA at the systemic level and in reduction of the endogenous antagonists for IL1 and TNF and of other cytokines related to the acute phase response , such as IL6, within days. At the synovial level, anti-TNF treatment does not modulate IL1 beta and TNF alpha in the short term. The synovial express ion of these cytokines does not reflect clinical response to TNF neutralisa tion.