Hydroxychloroquine Administration Mitigates Atherosclerotic Plaque Progression in ApoE Knockout Mice by Inhibiting Neutrophil Extracellular Trap Formation and Autophagy.

INTRODUCTION

Hydroxychloroquine (HCQ) has been associated with lower incidence of cardiovascular events in patients with autoimmune diseases and atherosclerosis progression in mouse models. Our study aimed at investigating the effect of HCQ on autophagy and neutrophil extracellular trap (NET) formation in aortas of ApoE-/- mice.

METHODS

ApoE-/- mice were treated with 10 mg/kg/day HCQ for 16 weeks. The aortas were examined histologically, while immunofluorescence staining and confocal microscopy were performed to identify the co-localization of myeloperoxidase (MPO) with DNA or microtubule-associated protein 1A/1B-light chain 3B (LC3B) as markers of NET formation and autophagy, respectively.

RESULTS

Among 52 ApoE-/- mice (30 male, 22 female), HCQ was administered in 15 male and 12 female mice. HCQ was associated with a significant reduction of the mean (±SD) surface of the atherosclerotic plaque compared to controls (HCQ-treated vs. control, 0.04 ± 0.01 mm2 vs. 0.08 ± 0.04 mm2, p < 0.01 and 0.06 ± 0.04 mm2 vs. 0.15 ± 0.09 mm2, p = 0.012, for male and female, respectively). This reduction was associated with a significant attenuation in the mean fluorescence intensity of MPO and LC3B expression in the atherosclerotic plaque of HCQ-treated mice (p = 0.03 and p = 0.01, respectively). In line with these findings, HCQ significantly reduced the proportion of MPO+ and LC3B+ cells within the atherosclerotic lesions.

CONCLUSIONS

HCQ administration in ApoE-/- mice may mitigate the progression of atherosclerotic plaque, by inhibiting autophagy and NET formation.