The Role of Circulating Regulatory T Cell Levels on Subclinical Atherosclerosis and Cardiovascular Risk Factors in Women with Systemic Lupus Erythematosus

The increase in cardiovascular disease (CVD) in patients with systemic lupus erythematosus (SLE) is not fully explained by traditional CVD risk factors. Regulatory T cells (Treg cells) are considered atheroprotective. We investigated the relationship between the absolute number of different phenotypes of Treg cells and abnormal carotid intima-media thickness (IMT) in women with SLE. Sixty-six women with SLE with no history of CV disease were included. Carotid IMT was quantified by ultrasound. Abnormal carotid IMT was defined as ≥0.8 mm and two groups were compared according to this definition. Flow cytometry was used to analyze Foxp3 and Helios expression in peripheral blood CD4 T cells. A significantly higher level of absolute CD4+CD25+FoxP3(high) T cells was present in patients with abnormal carotid IMT compared with those without (1.795 ± 4.182 cells/μl vs. 0.274 ± 0.784 cells/μl; p = 0.003). However, no correlations were found between any Treg cell phenotypes and carotid IMT. Only the absolute number of CD4+CD45RA+FoxP3(low) T cells was significantly decreased in SLE patients with low HDL cholesterol compared with those with normal HDL cholesterol (0.609 ± 2.362 cells/μl vs. 1.802 ± 4.647 cells/μl; p = 0.009 and 15.358 ± 11.608 cells/μl vs. 28.274 ± 34.139; p = 0.012, respectively). In conclusion, in SLE women, diminished levels of Treg cells based on flow cytometry were not a good indicator of abnormal carotid IMT.