The suppression of IgE-mediated histamine release from mast cells following exocytic exclusion of biodegradable polymeric nanoparticles

The objective of this study is to evaluate the effect of polymeric nanoparticles (NPs) on the allergic response of mast cells that release inflammatory mediators such as histamine through exocytosis. Submicron-sized biodegradable poly(dl-lactide-co-glycolide) (PLGA) NPs were prepared by the emulsion solvent diffusion method. Here, we examined the interactions of the mast cells with two types of PLGA NPs, unmodified NPs and NPs modified with chitosan (CS), a biodegradable cationic polymer. The cellular uptake of NPs increased by CS modification due to electrostatic interactions with the plasma membrane. NPs were taken up by mast cells through an endocytic pathway (endocytic phase) and then the cellular uptake was saturated and maintained plateau level by the exclusion of NPs through exocytosis (exocytic phase). Antigen-induced histamine release from mast cells was inhibited during the exocytic phase. The extent of histamine release inhibition was related to the amount of excluded NPs. Exocytic exclusion of NPs competitively antagonize the antigen-induced exocytotic release of histamine by highjacking exocytosis machinery such as SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins, since histamine release was recovered in mast cells that overexpress SNAP-23. The inhibitory effect of the allergic response by PLGA NPs was also evaluated in vivo using the mouse model for systemic anaphylaxis. The administration of NPs suppressed the antigen-induced systemic allergic response in vivo. In conclusion, PLGA NP itself has actions to inhibit the allergic responses mediated by mast cells.