Background: Nitric Oxide (NO) participation is recognized in numerous physiological and pathological processes. Rheumatoid arthritis (RA) is an inflammatory autoimmune disease involving joints and other systems including salivary glands. The role of NO in pathogenesis of development of RA is still unknown.
Aim & Objectives: We investigated NO concentration in saliva of 63 patients with RA and in 31 healthy control individuals. The aim of the study was also to investigate the correlation between saliva NO concentration and disease activity score (DAS28) in RA patients and to determine whether the statistically significant difference in saliva NO concentrations exists between RA patients with different stages of disease activity.
Methods: Patients with RA in this cross-sectional study have been divided, based on the stage of disease activity evaluated by DAS28score, into three subgroups: low disease activity (n=19), moderate disease activity (n=19) and high disease activity (n=25). NO concentration was determined by measuring nitrite concentration by Griess reaction. Conversion of nitrate (NO-3) to nitrite (NO-2) was done with elementary zinc. Absorbance was measured at 546 nm with the use of spectrophotometer.
Results: Results have shown that saliva NO concentration in patients with RA (33,2 ± 4,8 μmol/dm3) was statistically significant higher compared to saliva NO concentration in healthy controls (22,6 ± 2,3 μmol/dm3; p<0,05). We found statistically significant negative linear correlation between saliva NO concentration and DAS28 score in RA patients (r= -0,256; p<0,05). Statistically significant difference between saliva NO concentration in RA patients with different stages of disease activity was not found.
Conclusion: This study indicates that NO may play an important role in the pathogenesis of RA and saliva NO concentration probably can be used as useful biochemical marker for evaluation the disease activity of patients with RA.