Nano spray dryer for vectorizing α-galactosylceramide in polymeric nanoparticles: A single step process to enhance invariant Natural Killer T lymphocyte responses

The recognition of a-galactosylceramide (alpha GC), a high-affinity CD1d antigen, by the invariant Natural Killer T (iNKT) lymphocytes results in potent immunostimulatory responses that have been exploited in advanced cancer patients. Therefore, to improve alpha GC biological activity, several studies vectorized this agonist in PLGA and/or PEG-based nanoparticles. Despite promising findings, these approaches require several steps, from organic solvent decontamination through extrusion in membrane systems. Using a nano spray dryer, we vectorized alpha GC into a cationic copolymer (dimethylaminoethyl methacrylate, butyl methacrylate and methyl methacrylate - DBM) in a single step process, free of organic solvent. This methodology allowed the production of stable alpha GC-vectorized nanoparticles (DBM + alpha GC) with a more potent biological activity than the free agonist. DBM nanoparticles improved in vivo alpha GC loading into the CD1d molecule and induced a higher frequency of IFN-gamma-expressing iNKT cells. Consequently, mice treated with DBM + alpha GC presented higher levels of serum IFN-gamma than those treated with free agonist. Also, vectorized nanoparticles improved alpha GC ability to control the growth of murine lung metastatic carcinoma. Thus, this is the first study showing that nano spray dryer technology is a simple and alternative approach to enhance iNKT responses.