Patients with rheumatoid arthritis (RA), particularly those with severe disease, have increased risk of cardiovascular disease (CVD). Previous studies suggest that endothelial cell activation may contribute to this co-morbidity, and that treatment with tumour necrosis factor (TNF) inhibitors could reduce the risk of CVD in these patients. The aim of this study was to investigate endothelial cell activation markers in muscle tissue of patients after adalimumab treatment.
Patients with active RA who started treatment with adalimumab 40 mg every two weeks were included. Muscle biopsies taken before and 3 months after start of treatment were available from 11 patients (9 females, mean age 54.2 years, median disease duration 6.5 years, 91% anti-CCP positive, 7 on methotrexate [median dose 20 mg/week]). None of the patients had clinical signs of myopathy. IL-1α and HLA-DQ were investigated by immunohistochemistry. Quantification was performed by computer assisted image analysis.
Disease activity, measured by DAS28 decreased (mean 5.5 vs. 4.1; p=0018). A good or moderate EULAR response was seen in 6/11 patients. HLA-DQ was mainly expressed in endothelial cells in capillaries, whereas IL-1α was mainly seen in larger vessels. HLA-DQ expression decreased significantly after treatment (p=0.041). There was a similar trend for IL-1α, in particlar in EULAR good/moderate responders.
Adalimumab treatment was associated with decreased expression of endothelial markers previously associated with severe systemic inflammation in RA. Our findings indicate a reduced endothelial activation in patients treated with anti-TNF drugs, which might contribute to a lower risk of cardiovascular co-morbidity.