Biomarkers of subclinical atherosclerosis in patients with autoimmune disorders

Abstract

Atherosclerosis is accelerated in rheumatoid arthritis (RA) and psoriatic arthritis (PsA). We investigated a possible association of oxidized low-density lipoproteins (ox-LDLs), nitric oxide (NO), 3-nitrotyrosine, vitamin A, vitamin E, and β-carotene serum levels with subclinical atherosclerosis in RA and PsA. By the use of ELISA, we observed higher ox-LDL levels in patients with intima-media thickness (IMT) > 1 than in patients with IMT ≤ 1 and a negative correlation between NO levels and IMT values. By the use of high-performance liquid chromatography, we determined higher levels of vitamin A in patients with PsA and IMT ≤ 1 than in controls and lower levels of β-carotene in patients with RA and PsA than in controls. β-carotene concentrations were negatively correlated to the duration of disease in RA. Our study confirms that ox-LDLs and NO may be markers of accelerated atherosclerosis in RA and PsA whereas vitamins seem to be associated only to the presence of the autoimmune disorders.

Figure 1

Oxidized low-density lipoprotein (ox-LDL) concentrations in serum samples. Box plot graphs showing ox-LDL concentrations in serum samples from the 24 patients with rheumatoid arthritis (RA) and 25 with psoriatic arthritis (PsA), divided or not according to IMT values obtained by Echo-colour Doppler images and from the 13 healthy subjects. *P = 0.049; ^† P = 0.0095.

Figure 2

Nitric oxide (NO) concentrations in serum samples. Box plot graphs showing NO concentrations in serum samples from the 24 patients with rheumatoid arthritis (RA) and 25 with psoriatic arthritis (PsA), divided or not according to IMT values obtained by Echo-colour Doppler images and from the 13 healthy subjects. ^{∗ ‡ § #||} P < 0.0001; ^† P = 0.0008.

Figure 3

3-Nitrotyrosine concentrations in serum samples. Box plot graphs showing 3-nitrotyrosine concentrations in serum samples from the 24 patients with rheumatoid arthritis (RA) and the 25 patients with psoriatic arthritis (PsA), divided or not according to IMT values obtained by Echo-colour Doppler images and from the 13 healthy subjects. *P = 0.03.

Figure 4

Vitamin concentrations in serum samples. (a) Box plot graphs showing vitamin A concentrations in serum samples from the 24 patients with rheumatoid arthritis (RA) and 25 with psoriatic arthritis (PsA), divided or not according to IMT values obtained by Echo-colour Doppler images and from the 13 healthy subjects. *P = 0.0004; ^†  ‡ P = 0.0014. (b) β-carotene concentrations in sera. Box plot graphs showing β-carotene concentrations in serum samples from the 24 patients with rheumatoid arthritis (RA) and 25 with psoriatic arthritis (PsA), divided or not according to IMT values obtained by Echo-colour Doppler images and from the 13 healthy subjects. *P = 0.0021; ^§ P = 0.0008; ^† P = 0.006; ^# P = 0.018; ^‡ P = 0.0006. (c) Vitamin E concentrations in sera. Box plot graphs showing vitamin E concentrations in serum samples from the 24 patients with rheumatoid arthritis (RA) and 25 with psoriatic arthritis (PsA), divided or not according to IMT values obtained by Echo-colour Doppler images and from the 13 healthy subjects.

Figure 5

Correlations between clinical and serological variables. (a) Negative correlation between nitric oxide (NO) levels and intima-media thickness (IMT) values in rheumatoid arthritis (RA) and psoriatic arthritis (PsA) patients. R = −0.3, P = 0.033. (b) Negative correlation between β-carotene levels and the onset of the disease (evaluated in terms of year in which the disease was diagnosed) in RA patients. R = −0.62, P = 0.028.