Methotrexate improves endothelial function in early rheumatoid arthritis patients after 3 months of treatment

Abstract

Background: Endothelial dysfunction contributes to increased cardiovascular (CV) disease in rheumatoid arthritis (RA). Angiogenic T cells (Tang) are a key regulator of vascular function via their interaction with endothelial progenitor cells (EPCs). Methotrexate (MTX) has been associated to reduced CV disease risk, but its effects on endothelial homeostasis have been poorly explored. We investigated MTX effects on endothelial homeostasis in early, treatment-naïve RA patients.

Methods: Fifteen untreated, early RA patients and matched healthy controls (HC) were enrolled. RA patients with long-standing disease in remission or low disease activity treated with MTX for at least 6 months were selected as controls. Circulating CD28⁺ and CD28^null Tang cell, endothelial microparticle (EMP), EPC and soluble vascular cell adhesion molecule (sVCAM)-1 levels were measured.

Results: Tang percentage was higher in early RA than in HCs and significantly increased after 3-month MTX treatment. Tang cells in RA were characterized by higher percentage of CD28^null and lower CD28-positive cells than HCs. MTX restored a Tang cell phenotype similar to HCs. Altered sVCAM-1, EMP and EPC were restored to levels similar to HCs after a 3-month MTX. Biomarker levels after 3 months of MTX were not different to those of patients with long-standing treatment.

Conclusions: MTX has a positive effect on Tang, sVCAM-1, EPCs and EMPs in RA. Restoration of imbalance between CD28 + and CD28^null Tang by MTX may be one of the mechanisms underlying its favourable effects on endothelial dysfunction. These effects seem to be long-lasting and independent from systemic inflammation reduction, suggesting a direct effect of MTX on the endothelium.

Keywords: Angiogenic T cells; Cardiovascular disease; Endothelial dysfunction; Methotrexate; Microvesicles; Platelets; Rheumatoid arthritis.

Fig. 1

Effects of methotrexate on biomarkers of endothelial dysfunction. Circulating Tang cells are more prevalent in early RA compared to HCs, and their number further increases following MTX treatment (A). Early RA patients show an altered balance of Tang cells in favour of a CD28^nullphenotype which is restored following MTX treatment (B). In RA patients, 3-month MTX treatment restores sVCAM-1 (C), EMP (D), platelet CD40L (E) and EPC (G) to levels of HCs. CEC levels do not display significant differences (F). Data are shown as mean ± standard error. *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001, ****p ≤ 0.0001

Fig. 2

Correlation of endothelial dysfunction biomarkers changes with disease activity. The variation (Δ) of circulating Tang cells (A), CD28 + Tang cells (B), sVCAM-1 (C), EMPs (D), platelet CD40L (E) and EPCs (F) after 3 months of MTX treatment does not correlate with the change in disease activity according to DAS28-CRP