Apoptotic body-inspired nanoparticles target macrophages at sites of inflammation to support an anti-inflammatory phenotype shift.

Chronic inflammation is a significant pathological process found in a range of disease states. Treatments to reduce inflammation in this family of diseases may improve symptoms and disease progression, but are largely limited by variable response rates, cost, and off-target effects. Macrophages are implicated in many inflammatory diseases for their critical role in the maintenance and resolution of inflammation. Macrophages exhibit significant plasticity to direct the inflammatory response by taking on an array of pro- and anti-inflammatory phenotypes based on extracellular cues. In this work, a nanoparticle has been developed to target sites of inflammation and reduce the inflammatory macrophage phenotype by mimicking the anti-inflammatory effect of apoptotic cell engulfment. The nanoparticle, comprised of a poly(lactide-co-glycolide) core, is coated with phosphatidylserine (PS)-supplemented cell plasma membrane to emulate key characteristics of the apoptotic cell surface. The particle surface is additionally functionalized with an acid-sensitive sheddable polyethylene glycol (PEG) moiety to increase the delivery of the nanoparticles to low pH environments such as those of chronic inflammation. In a mouse model of lipopolysaccharide-induced inflammation, particles were preferentially taken up by macrophages at the site and promoted an anti-inflammatory phenotype shift. This PEGylated membrane coating increased the delivery of nanoparticles to sites of inflammation and may be used as a tool alone or as a delivery scheme for additional cargo to reduce macrophage-associated inflammatory response.