Use of acidic nanoparticles to rescue macrophage lysosomal dysfunction in atherosclerosis

ABSTRACTDysfunction in the macrophage lysosomal system including reduced acidity and diminished degradative capacity is a hallmark of atherosclerosis, leading to blunted clearance of excess cellular debris and lipids in plaques and contributing to lesion progression. Devising strategies to rescue this macrophage lysosomal dysfunction is a novel therapeutic measure. Nanoparticles have emerged as an effective platform to both target specific tissues and serve as drug delivery vehicles. In most cases, administered nanoparticles are taken up non-selectively by the mononuclear phagocyte system including monocytes/macrophages leading to the undesirable degradation of cargo in lysosomes. We took advantage of this default route to target macrophage lysosomes to rectify their acidity in disease states such as atherosclerosis. Herein, we develop and test two commonly used acidic nanoparticles, poly-lactide-co-glycolic acid (PLGA) and polylactic acid (PLA), both in vitro and in vivo. Our results in cultured macrophages indicate that the PLGA-based nanoparticles are the most effective at trafficking to and enhancing acidification of lysosomes. PLGA nanoparticles also provide functional benefits including enhanced lysosomal degradation, promotion of macroautophagy/autophagy and protein aggregate removal, and reduced apoptosis and inflammasome activation. We demonstrate the utility of this system in vivo, showing nanoparticle accumulation in, and lysosomal acidification of, macrophages in atherosclerotic plaques. Long-term administration of PLGA nanoparticles results in significant reductions in surrogates of plaque complexity with reduced apoptosis, necrotic core formation, and cytotoxic protein aggregates and increased fibrous cap formation. Taken together, our data support the use of acidic nanoparticles to rescue macrophage lysosomal dysfunction in the treatment of atherosclerosis.Abbreviations: BCA: brachiocephalic arteries; FACS: fluorescence activated cell sorting; FITC: fluorescein-5-isothiocyanatel; IL1B: interleukin 1 beta; LAMP: lysosomal associated membrane protein; LIPA/LAL: lipase A, lysosomal acid type; LSDs: lysosomal storage disorders; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MFI: mean fluorescence intensity; MPS: mononuclear phagocyte system; PEGHDE: polyethylene glycol hexadecyl ether; PLA: polylactic acid; PLGA: poly-lactide-co-glycolic acid; SQSTM1/p62: sequestosome 1KEYWORDS: Acidic nanoparticlesatherosclerosislysosomal dysfunctionmacrophagePLGA AcknowledgmentsThis work was supported by NIH R03 EG028026 01, and NIH R43HL151073. Cell sorting and flow cytometry data acquisition and analysis provided by the Flow Cytometry Core facility, Department of Pathology and Immunology, Washington University School of Medicine. Live imaging analysis provided by Washington University Center for Cellular Imaging.Disclosure statementD.P. is the founder/co-founder of three university start-ups. None of these entities, however, supported this work.Supplementary materialSupplemental data for this article can be accessed online at https://doi.org/10.1080/15548627.2022.2108252Correction StatementThis article has been republished with minor changes. These changes do not impact the academic content of the article.Additional informationFundingThis work was supported by the National Institutes of Health [R01 HL125838]; National Institutes of Health [R01 DK121560]; National Institutes of Health [P30 DK056341]; National Institutes of Health [T32 HL134635]; u.s. department of veterans affairs [I01 BX003415], American Heart Association [897628].