Genotype-dependent NOS-3 expression and rheumatoid arthritis

The ^-786C-variant of the endothelial nitric oxide synthase nos-3 gene has been shown to be associated with coronary artery disease because of a blunted inducibility of gene expression [1]. IL-10, a cytokine involved in T_H1/T_H2-cell differentiation, is a new stimulus for NOS-3 expression [2].

We here address the question whether IL-10-induced NOS-3 expression is decreased in individuals with the ^-786C/C genotype and, if so, whether a T_H1-mediated disease like rheumatoid arthritis is associated with this genotype.

Endothelial cells were isolated from an umbilical cord vein of known genotype and cultured as described [1]. The expression of NOS-3 was analysed by real-time semi-quantitative RT-PCR [1]. Genotyping was performed as described elsewhere [1]. Patients met the revised criteria of the ACR for the classification of rheumatoid arthritis, and donated blood samples after informed consent.

Primary human umbilical vein endothelial cells with the ^-786C/C genotype did not respond with an increase in NOS-3 expression to IL-10 incubation (5 ng/ml). This defect could be repaired after pre-incubation of the cells with a decoy oligonucleotide (10 μmol/l) directed against the C-variant of the promoter. Among 587 patients with rheumatoid arthritis tested, incidences for the ^-786C/C genotype were significantly higher than in the general population (17% versus 11.7%; P < 0.01).

NOS-3 is one mediator of anti-inflammatory IL-10 actions. Individuals with the ^-786C/C nos-3-genotype have an increased risk for the development of rheumatoid arthritis. This might be due to the IL-10 insensitivity of the C-variant of the promoter.