Vasoactive Intestinal Peptide Amphiphile Micelle Chemical Structure and Hydrophobic Domain Influence Immunomodulatory Potentiation

Abstract

Vasoactive intestinal peptide (VIP) is a neuropeptide capable of downregulating innate immune responses in antigen presenting cells (APCs) by suppressing their pro-inflammatory cytokine secretion and cell surface marker expression. Though VIPs bioactivity could possibly be leveraged as a treatment for autoimmune disorders and transplant tolerance, drug delivery innovation is required to overcome its intrinsically limited cellular delivery capacity due to its short in vivo lifetime. One option is to employ peptide amphiphiles (PAs) which are lipidated peptides capable of self-assembling into micelles in water that can enhance cellular association. With this approach in mind, a series of triblock VIP amphiphiles (VIPAs) has been synthesized to explore the influence of block arrangement and hydrophobicity on micelle biocompatibility and bioactivity. VIPA formulation has been found to influence the shape, size, and surface charge of VIPA micelles (VIPAMs) as well as their cytotoxicity and immunomodulatory effects. Specifically, the enclosed work provides strong evidence that cylindrical VIPAMs with aspect ratios of 1.5 - 150 and moderate positive surface charge are able to potentiate the bioactivity of VIP limiting TNF- secretion and MHC II and CD86 surface expression on APCs. With this criteria, we have identified PalmK-(EK)4-VIP as our lead formulation, which showed comparable or enhanced anti-inflammatory effects relative to the unmodified VIP at all dosages evaluated. Additionally, the relationships between peptide block location and lipid block size provide further information on the chemistry-structure-function relationships of peptide amphiphile micelles for the delivery of VIP as well as potentially for other peptides more broadly.