Pain processing in rheumatoid arthritis patients successfully treated with anti-TNF medication
Wordsworth P., Schweinhardt P., Chizh BA., Chessell I., Tracey I., Wartolowska K.
Introduction: Anti-TNF treatment blocks the action of proinflammatory cytokine, tumor necrosis factor, and reduces pain and disease activity in rheumatoid arthritis (RA). We were interested in changes in processing of evoked pain in RA patients after successful anti-TNF treatment. Methods: Ten patients with severe RA were scanned before the beginning of treatment and after 6 months of successful therapy. 22 healthy volunteers were recruited as a control group and were scanned only once. We used fMRI to investigate brain activation changes in response to joint pressure pain and thermal stimulation at a fixed temperature to elicit moderate pain. Results: At the baseline, the comparison of moderately painful pressure pain in patients vs. non-painful pressure stimulation in controls revealed more extensive activation in the anterior cingulate cortex, the brainstem and bilaterally in the thalamus and insula. As for the thermal stimulation, patients and controls rated it as moderately painful, however, there was less activation in the thalamus and insula in patients than in controls. Patients were scanned again after six months of the treatment and the same stimulation intensity was used as at the baseline. Joint pressure pain was rated significantly lower, whereas thermal pain ratings remained the same. In comparison to the control group imaging data, patients showed more activation in response to pressure stimulation in the cingulate cortex and brainstem; patients’ brain activation in response to thermal stimulation was not different from controls. Conclusions: We observed a normalization of pain processing after successful anti-TNF treatment. The study was funded by GlaxoSmithKline as a part of an ongoing academic collaboration.