Peptoids as potential therapeutics to reduce S100B-induced RAGE-associatedneuroinflammation in Alzheimer's disease.

Abstract

Receptor for advanced glycation end-products (RAGE)-associated chronic neuroinflammation has been linked with Alzheimer's disease (AD) pathology. RAGE ligand S100B, which is elevated in AD brain, can induce release of inflammatory cytokines and upregulate RAGE. Consequently, targeting RAGE to reduce chronic inflammation represents a novel therapeutic strategy for AD. Peptoids are ideal potential AD therapeutics as they resist proteolytic degradation by repositioning side-chains from the α-carbon to the amide nitrogen and exhibit facile blood-brain barrier permeability. Peptoids designed to mimic RAGE ligands demonstrated strong binding affinity to RAGE in our previous studies. We hypothesize that these peptoids can attenuate S100B-induced activation of RAGE, thus reducing pro-inflammatory cytokine release associated with chronic neuroinflammation. Differentiated THP-1 macrophages were exposed to chronic low-levels of S100B to confirm upregulation of cytokine release. Macrophages were then treated with 0-50-μM peptoids (JPT1 or JPT1a) in the presence of S100B. To observe peptoid modulation of S100B-induced inflammation, cytokine analysis via immunoassay was performed using cell culture supernatants. Additionally, RAGE was incubated in the presence of 0-500-nM peptoid to achieve equilibrium. Unbound RAGE was quantified via modified ELISA to determine the binding affinity. S100B-treated THP-1 macrophages elicited anticipated inflammatory response evidenced by dose-dependent upregulation of cytokines. When THP-1 macrophages were incubated with peptoids and S100B, peptoids attenuated these S100B-induced inflammatory responses. Moreover, the peptoids demonstrated nanomolar binding affinity for RAGE. Peptoids modulate inflammatory responses induced by RAGE ligand S100B, including inflammatory cytokine release. These results implicate peptoids as a potential therapeutic agent for not only AD but also other inflammation-related illnesses. Because these peptoids have additionally exhibited the ability to modulate Aβ aggregation and transform the morphology of the aggregates formed, they may function as dual-target therapeutics for AD.