Self-Assembled Nanochaperones Inhibit the Aggregation of Human Islet Amyloid Polypeptide Associated with Type 2 Diabetes

Polymeric micelles as potent islet amyloid inhibitors: current advances and future perspectives

Diabetes mellitus (DM) has become one of the most prevalent diseases across the globe, mainly because of the inability of existing treatment strategies to target its root cause (i.e., pancreatic β cell damage). Polymeric micelles (PMs) have gained attention as a treatment option for DM by targeting misfolded islet amyloid polypeptide protein (IAPP), which is common in more than 90% of patients with DM patients. Such misfolding could result from either oxidative stress or mutation in the gene encoding IAPP. In this review, we discuss progress in the design of PMs to halt islet amyloidosis along with their mechanism and dynamics of interactions with IAPP. We also discuss the clinical challenges associated with the translation of PMs as anti-islet amyloidogenic agents. Teaser: Polymeric micelles are able to target misfolding of islet amyloid polypeptide protein in the pancreas owing to their amphiphilic properties and could help protect against β cell damage, thereby offering effective management of diabetes mellitus.

Gold Nanoclusters Enhance the Efficacy of the Polymer-Based Chaperone in Restoring and Maintaining the Native Conformation of Human Islet Amyloid Polypeptide

The misfolding and un-natural fibrillation of proteins/peptides are associated with many conformation diseases, such as human islet amyloid polypeptide (hIAPP) in type 2 diabetes (T2D). Inspired by molecular chaperones maintaining protein homeostasis in vivo, many polymer-based artificial chaperones were introduced to regulate protein/peptide folding and fibrillation. However, the pure polymer chaperones prefer to agglomerate into large-size micelles in the physiological environment and thus lose their chaperone functions, which greatly restricts the application of polymer-based chaperones. Here, we designed and prepared a core-shell artificial chaperone based on a dozen poly-(N-isopropylacrylamide-co-N-acryloyl-O-methylated-l-arginine) (PNAMR) anchored on a gold-nanocluster (AuNC) core. The introduction of the AuNC core significantly reduced the size and enhanced the efficacy and stability of polymer-based artificial chaperones. The PNAMR@AuNCs, with a diameter of 2.5 ± 0.5 nm, demonstrated exceptional ability in maintaining the natively unfolded conformation of protein away from the misfolding and the following fibrillation by directly binding to the natively unfolded monomolecular hIAPP and hence in preventing their conversion into toxic oligomers. More excitingly, the PNAMR@AuNCs were able to restore the natural unfolded conformation of hIAPP via dissolving the β-sheet-rich hIAPP fibrils. Considering the uniform molecular mechanism of protein misfolding and fibrillation in conformation disorders, this finding provides a generic therapeutic strategy for neurodegenerative diseases and other conformation diseases by using PNAMR@AuNC artificial chaperones to restore and maintain the native conformation of amyloid proteins.

Glucose-Responsive Nanochaperones Mediate Exendin-4 Delivery for Enhancing Therapeutic Effects

Exendin-4 (Ex-4) is a promising therapeutic peptide for the clinical treatment of type 2 diabetes, but its instability and immunogenicity result in a short circulating half-life and low bioavailability, which severely limit its clinical application. Here, complex micelles with 4-carboxy-3-fluorophenylboronic acid (FPBA)-modified and positively charged hydrophobic domains on the surface were devised as nanochaperones to mediate the delivery of Ex-4. The nanochaperones can bind Ex-4 on the surface via the synergy of electrostatic and hydrophobic interactions, leading to efficient loading and stabilization of Ex-4. More importantly, the immunogenic site of Ex-4 was shielded by the nanochaperones, thereby effectively reducing the immune clearance and prolonging the half-life. Hyperglycemia-triggered release of Ex-4 was achieved by the hydrophobic to the hydrophilic transformation of the FPBA-modified domains and the introduced negative charge because of the binding of glucose by FPBA. The Ex-4-loaded nanochaperones exhibited an enhanced therapeutic effect on type 2 diabetic mice.

Biomedical Applications of polymeric micelles in the treatment of diabetes mellitus: Current success and future approaches

INTRODUCTION

Diabetes mellitus (DM) is the most common metabolic disease and multifactorial, harming patients worldwide. Extensive research has been carried out in the search for novel drug delivery systems offering reliable control of glucose levels for diabetics, aiming at efficient management of DM.

AREAS COVERED

Polymeric micelles (PMs) as smart drug delivery nanocarriers are discussed, focusing on oral drug delivery applications for the management of hyperglycemia. The most recent approaches used for the preparation of smart PMs employ molecular features of amphiphilic block copolymers (ABCs), such as stimulus sensitivity, ligand conjugation, and as a more specific example the ability to inhibit islet amyloidosis.

EXPERT OPINION

PMs provide a unique platform for self-regulated or spatiotemporal drug delivery, mimicking the working mode of pancreatic islets to maintain glucose homeostasis for prolonged periods. This unique characteristic is achieved by tailoring the functional chemistry of ABCs considering the physicochemical traits of PMs, including sensing capabilities, hydrophobicity, etc. In addition, the application of ABCs for the inhibition of conformational changes in islet amyloid polypeptide garnered attention as one of the root causes of DM. However, research in this field is limited and further studies at the clinical level are required.

Dual-targeted carbon-dot-drugs nanoassemblies for modulating Alzheimer's related amyloid-β aggregation and inhibiting fungal infection

Amyloid aggregation and fungal infection, especially amyloid beta (Aβ) peptide and Candida albicans are considered as two of the crucial pathogenic agents in Alzheimer's disease (AD). In this work, we propose an innovative treatment strategy for AD, targeting at not only Aβ aggregation but also Candida albicans infection. Here, a high-performance nanomaterial, namely gCDs-E, have been prepared by self-assembled of glycosylated carbon dots (gCDs) and epigallocatechin-3-gallate (EGCG). Surprisingly, gCDs-E can not only suppress the fibrillation of Aβ and disaggregate Aβ fibrils, but also effectively inhibit the activity of Candida albicans. More importantly, the prepared gCDs-E can effectively cut down the cytotoxicity of amyloid aggregations, and the cell viability reached to 99.2%. In addition, the capability of the gCDs-E for blood brain barrier (BBB) penetration was also observed using a normal mice model. Above all, the gCDs-E greatly cleaned Aβ deposition and improved memory impairment in APP/PS1 transgenic AD model mice, confirming its potential as therapeutic agent for AD treatment.