Background/Purpose: Patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) are at high risk of atherosclerosis and have high mortality due to cardiovascular disease. Oxidative stress is involved in the progression of atherosclerosis, with the percentage of human non-mercaptoalbumin (HNA%), the oxidized form of human serum albumin, attracting considerable attention as a potential biomarker of oxidative stress. Although previous studies have shown increased HNA% in the elderly people and in patients with either chronic kidney disease, diabetes mellitus, or liver cirrhosis, there are no reports on HNA% in patients with rheumatic diseases. The aim of this study was to evaluate HNA% in patients with SLE or RA and to identify factors associated with this biomarker.

Methods: We measured HNA% in patients with SLE, RA, and healthy controls by using high-performance liquid chromatography. Analysis of covariance was used to compare HNA% between SLE and healthy controls, or RA and healthy controls. Factors associated with HNA% in SLE and RA patients were assessed by using multiple linear regression analysis.

Results: HNA% was measured in 89 SLE patients [age (mean ± SD), 44 ± 11 years; female, 97%], 51 RA patients [age (mean ± SD), 62 ± 13 years; female, 94%], and 65 healthy controls [age (mean ± SD), 55 ± 14 years; female, 58%)]. All participants were Japanese. Mean HNA% (SD) of SLE, RA, and healthy controls were 23.0% (5.0%), 23.7% (4.7%), and 21.8% (3.7%), respectively. The correlation between HNA% and age was significant in RA patients and healthy controls, but not in SLE patients (Figure 1). The age-adjusted mean difference in HNA% between the SLE patients and the healthy controls was 2.9% (95% CI, 0.96 to 4.9%; Bonferroni corrected p value = 0.001), and between the RA patients and the healthy controls, 0.84% (95% CI, −3.0 to 1.3%; Bonferroni corrected p value=1.0), respectively. In SLE patients, SLICC/ACR damage index (β=0.48, p< 0.001) and serum creatinine level (β=0.24, p=0.01) were significantly associated with HNA%. In RA patients, serum creatinine level (β=0.42, p< 0.001), age (β=0.37, p=0.002), and daily prednisolone dosage (β=0.29, p=0.006) were significantly associated with HNA%.

Conclusion: SLE patients have increased HNA% compared to the healthy controls, especially in association with the SLICC/ACR damage index. Patients with RA do not show this association. In SLE patients, increased HNA% might reflect excessive oxidative stress and possibly be associated with an increased risk of atherosclerosis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/oxidized-human-serum-albumin-is-increased-in-systemic-lupus-erythematosus-but-not-in-rheumatoid-arthritis/