Macrophage
inflammation and maturation into foam cells, following
the engulfment of oxidized low-density lipoproteins (oxLDL), are major
hallmarks in the onset and progression of atherosclerosis. Yet, chronic
treatments with anti-inflammatory agents, such as methotrexate (MTX),
failed to modulate disease progression, possibly for the limited drug
bioavailability and plaque deposition. Here, MTX–lipid conjugates,
based on 1,2-distearoyl-
sn
-glycero-3-phosphoethanolamine
(DSPE), were integrated in the structure of spherical polymeric nanoparticles
(MTX-SPNs) or intercalated in the lipid bilayer of liposomes (MTX-LIP).
Although, both nanoparticles were colloidally stable with an average
diameter of ∼200 nm, MTX-LIP exhibited a higher encapsulation
efficiency (>70%) and slower release rate (∼50% at 10 h)
compared
to MTX-SPN. In primary bone marrow derived macrophages (BMDMs), MTX-LIP
modulated the transcellular transport of oxLDL more efficiently than
free MTX mostly by inducing a 2-fold overexpression of ABCA1 (regulating
oxLDL efflux), while the effect on CD36 and SRA-1 (regulating oxLDL
influx) was minimal. Furthermore, in BMDMs, MTX-LIP showed a stronger
anti-inflammatory activity than free MTX, reducing the expression
of IL-1β by 3-fold, IL-6 by 2-fold, and also moderately of TNF-α.
In 28 days high-fat-diet-fed apoE
–/–
mice,
MTX-LIP reduced the mean plaque area by 2-fold and the hematic amounts
of RANTES by half as compared to free MTX. These results would suggest
that the nanoenhanced delivery to vascular plaques of the anti-inflammatory
DSPE-MTX conjugate could effectively modulate the disease progression
by halting monocytes’ maturation and recruitment already at
the onset of atherosclerosis.