Background: Patients with rheumatoid arthritis (RA) have endothelial dysfunction, which may predispose them to the risk of premature atherosclerosis. This study investigated the involvement of tumor necrosis factor (TNF) alpha in the pathophysiologic characteristics of this abnormality by use of the TNF-alpha-neutralizing antibody infliximab.
Methods: Endothelium-dependent and -independent vasodilator responses to intra-arterial infusion of increasing doses of acetylcholine and sodium nitroprusside, respectively, were assessed by strain-gauge plethysmography in patients (n = 10) with early RA during saline solution infusion and after intra-arterial infusion of infliximab (200 microg/min).
Results: Circulating markers of systemic inflammation (C-reactive protein and interleukin 6) were higher in patients than in control subjects (n = 10, both P < .05), whereas plasma levels of TNF-alpha and soluble TNF receptor types 1 and 2 were similar in both groups (all P > .05). During saline solution infusion, the vasodilator response to acetylcholine was blunted in patients with RA compared with control subjects (14.2 +/- 9.2 mL . min-(1). dL-(1) versus 23.7 +/- 9.2 mL . min-(1). dL-(1) at the highest dose, P = .004) whereas vasodilation to sodium nitroprusside was not different between groups (P = .10). In patients with RA infliximab did not modify circulating C-reactive protein levels (P = .29, versus saline solution) but did potentiate the vasodilator response to acetylcholine (21.0 +/- 11.1 mL . min-(1). dL-(1); P = .004, versus saline solution). The response to sodium nitroprusside, in contrast, was not modified by infliximab (P = .28 versus saline solution).
Conclusions: Intravascular administration of anti-TNF-alpha antibody ameliorates endothelial function in patients with RA but does not concurrently affect systemic inflammatory changes. Our findings suggest that enhanced TNF-alpha generation within the vessel wall, rather than systemic mechanisms, plays a role in the pathobiologic features of endothelial dysfunction in RA.