Microfluidic chambers for monitoring leukocyte trafficking and humanized nano-proresolving medicines interactions

Abstract

Leukocyte trafficking plays a critical role in determining the progress and resolution of inflammation. Although significant progress has been made in understanding the role of leukocyte activation in inflammation, dissecting the interactions between different leukocyte subpopulations during trafficking is hampered by the complexity of in vivo conditions and the lack of detail of current in vitro assays. To measure the effects of the interactions between neutrophils and monocytes migrating in response to various chemoattractants, at single-cell resolution, we developed a microfluidic platform that replicates critical features of focal inflammation sites. We integrated an elastase assay into the focal chemotactic chambers (FCCs) of our device that enabled us to distinguish between phlogistic and nonphlogistic cell recruitment. We found that lipoxin A(4) and resolvin D1, in solution or incorporated into nano-proresolving medicines, reduced neutrophil and monocyte trafficking toward leukotriene B(4). Lipoxin A(4) also reduced the elastase release from homogenous and heterogenous mixtures of neutrophils and monocytes. Surprisingly, the effect of resolvin D1 on heterogenous mixtures was antisynergistic, resulting in a transient spike in elastase activity, which was quickly terminated, and the degraded elastin removed by the leukocytes inside the FCCs. Therefore, the microfluidic assay provides a robust platform for measuring the effect of leukocyte interactions during trafficking and for characterizing the effects of inflammation mediators.

Resolvin D1 Polarizes Primary Human Macrophages toward a Proresolution Phenotype through GPR32

“…On the one hand, there is evidence that RvD1 directly reduces human neutrophil migration toward IL-8 (42,43) and leukotriene B 4 (data not shown), and on the other hand, we now show that RvD1-treated macrophages secrete less IL-8. Such a combined effect on the chemotactic activity of neutrophils and on the secretion of the chemotactic agent by macrophages may well be an efficient mechanism to block neutrophil immigration into the inflamed area.…”

Aging Delays Resolution of Acute Inflammation in Mice: Reprogramming the Host Response with Novel Nano-Proresolving Medicines

“…Biomimicking endogenous resolving pathways using nano-proresolving medicines constructed from neutrophil microparticles enhances the bioactions of SPM (17). Therefore, we next questioned whether NPRM could rectify the overt inflammatory response in aged mice, restoring homeostasis.…”

“…LXA 4 or RvD1, exert anti-inflammatory and proresolving actions contributing to resolution (10, 17). Since reprogrammed monocytes displayed potent proresolving actions (Figure 5), their microparticles were used as scaffolds for constructing of new biomimetics for SPM delivery in aged mice.…”

Proresolving Nanomedicines Activate Bone Regeneration in Periodontitis

“…In experiments including transgenic rabbits systems (Serhan et al 2003), topical application of lipoxin stable analogs dramatically reduced leukocyte infiltration, bone loss, and inflammation. LX-enriched humanized NPRM likewise reduced PMN influx in murine peritonitis, accelerated healing, and protected against temporomandibular joint inflammation (Norling et al 2011;Jones et al 2012), indicating that LX-enriched NPRM offer new therapeutic approaches as mimetics of endogenous resolution of inflammation mechanisms with potent beneficial bioactions in vivo.…”