Increased myeloperoxidase plasma levels in rheumatoid arthritis

Abstract

High myeloperoxidase (MPO) serum levels have been shown in several inflammatory diseases, including rheumatoid arthritis (RA). However, the correlation between MPO levels and disease activity in RA patients is still controversial. The aim of the study was to determine MPO plasma levels in RA patients and to investigate potential correlations between MPO levels and disease activity and treatment. MPO plasma levels were measured by ELISA according the manufacturer's instructions. Disease activity was measured by DAS28 ESR and DAS28 CRP scores, and patients were classified into 4 groups: group 1 DAS28 < 2.6; group 2: 2.6 ≤ DAS28 ≤ 3.2; group 3: 3.2 < DAS28 ≤ 5.1 and group 4: DAS28 > 5.1. Rheumatoid factor (RF) was measured by latex agglutination test, and anti-cyclic citrullinated peptide (anti-CCP) antibodies were detected by ELISA with a commercial kit. Fifty-seven female RA patients (mean age: 46.02 ± 13.47 years, mean disease duration: 115.77 ± 99.44 months) and sixty gender- and age-paired healthy controls were included. Mean MPO plasma levels were significantly higher in patients than in controls (72.27 pM vs. 40.78 pM, P = 0.007). RF was found in 59.6% and anti-CCP in 80.7% of the RA patients. No significant difference in MPO levels was seen among the four RA disease activity groups. We did not find significant correlation between MPO levels and disease activity as measured by DAS28 score. In conclusion, we observed significantly higher MPO plasma levels in RA patients when compared to healthy controls. However, we did not find correlation between MPO plasma level and disease activity.

Increased levels of serum myeloperoxidase in patients with active rheumatoid arthritis

“…The significance of serum MPO in RA has been reported in a few recently published studies, and the associations between serum MPO levels and disease variables are still controversial (Stamp et al, 2012;Fernandes et al, 2012). In the present study, we observed that serum MPO levels were associated with disease activity indicators in RA patients, and that increased MPO concentrations were more likely to occur in patients with higher DAS28, and those with elevated inflammatory indicators (CRP, and the neutrophil percentage).…”

“…In addition, both plasma MPO and MPO in synovial fluid were proved to be active in their study. By contrast, another previous study found no significant association between serum MPO and DAS28, although they observed increased MPO plasma levels in RA patients (Fernandes et al, 2012). The patient cohort analyzed by Fernandes et al included only 57 female patients with RA from Latin America, thus their study might have lacked statistical power on account of the relatively small study population.…”

“…Although this group did not find a correlation between plasma MPO levels and disease activity, the patients with articular involvement showed significantly higher MPO levels, suggesting a different role in the inflammatory development of certain SLE manifestations (Telles et al, 2010). Elevated serum MPO concentrations have also been observed in RA patients when compared to healthy controls, and have been shown to promote oxidative stress in RA patients (Stamp et al, 2012;Fernandes et al, 2012). In our study cohorts, RA, SLE, DM, and AS patients showed higher MPO concentrations than the healthy controls.…”

Myeloperoxidase: A new player in autoimmunity

“…This concept is supported by the finding that both intracellular and extracellular MPO was shown to be present in the synovium of RA patients [82]. In addition, RA patients were shown to have increased plasma levels of MPO compared to healthy controls [83,84]. However, there was inconsistency as to the correlation between MPO levels in the plasma and disease activity score, as one study showed correlation, while another did not [83,84].…”

High density lipoprotein is targeted for oxidation by myeloperoxidase in rheumatoid arthritis

“…RA is associated with altered pro-inflammatory HDL22 23 and increased MPO level and activity 24 25. Impaired RCT has been reported in RA patients with high disease activity and levels of plasma MPO correlated with this impairment 26.…”