Modification of primary amines to higher order amines reduces in vivo hematological and immunotoxicity of cationic nanocarriers through TLR4 and complement pathways

Randall Toy; Pallab Pradhan; Vijayeetha Ramesh; Nelson C. Di Paolo; Blake Lash; Jiaying Liu; Emmeline L. Blanchard; Philip J. Santangelo; Dmitry M. Shayakhmetov; Krishnendu Roy

The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. . https://doi.org/10.1101/647305 doi: bioRxiv preprint modification prevented upregulation of IL-6, CXCL1, and IL-1b by chitosan nanoparticleswhich indicate that as with bPEI, IAA reduces innate immune activation by chitosan. At the same time, IAA modification also increased neutrophil uptake of chitosan nanoparticles and in vivo complement activation. This seems paradoxical, given that complement activation is typically considered pro-inflammatory. Complement fragments, however, have been shown to enhance the anti-inflammatory activity of neutrophil extracellular traps on TLR4-activated macrophages. [47] , [48] Evidence of enhanced neutrophil uptake, heightened complement activation, and reduced IL-6 enable this to be a plausible mechanism for the reduced in vivo systemic toxicity of IAA-modified chitosan. This complex phenomenon between multiple cell types could explain the disparity between our in vivo and in vitro toxicity results with chitosanwhere IAA-modified chitosan nanoparticles induced a strong innate immune response from BMDCs. When toxicity is evaluated in vitro, the internalization rate of the nanoparticles is the primary driver of toxicity -as chitosan is known to activate the cGAS sensor in the cytosol.