Heterocyclic Molecules Tethered Branched Polymers with Innate Immune Stimulating Activity

We report herein an interesting finding that heterocyclic molecules tethered branched polymers exhibit innate immune stimulating activity.When we conjugated a series of five-,six-,or seven-membered heterocyclic molecules to branched polyethylenimine(bPEI),over 70%of them could induce the secretion of interferon-β(IFN-β)from murine dendritic and human leukemia monocytic(DC2.4 and THP-1)cells through activating the stimulator of interferon genes(STING)pathway.We further proved that this kind of innate stimulating activity was dependent on the macromolecular architecture as heterocyclic molecules tethered linear PEI(lPEI)or dendritic polyamidoamine(PAMAM)induced no or much less IFN-βsecretion.Furthermore,we prepared a series of poly-L-lysine(PLL)-derivatives with different branches to tether with heterocyclic molecules and proved that this kind of bPEI-like structure was important in en hancing the binding affinity with STING proteins and for exhibiting innate stimulating activity.

Graphene quantum dots rescue protein dysregulation of pancreatic β-cells exposed to human islet amyloid polypeptide

The amyloid aggregation of peptides and proteins is a hallmark of neurological disorders and type 2 diabetes.Human islet amyloid polypeptide(IAPP),co-secreted with insulin by pancreaticβ-cells,plays dual roles in both glycemic control and the pathology of type 2 diabetes.While IAPP can activate the NLRP3 inflammasome and modulate cellular autophagy,apoptosis and extracellular matrix metabolism,no data is available concerning intracellular protein expression upon exposure to the polypeptide.More surprisingly,how intracellular protein expression is modulated by nanoparticle inhibitors of protein aggregation remains entirely unknown.In this study,we first examined the changing proteomes ofβTC6,a pancreaticβ-cell line,upon exposure to monomeric,oligomeric and fibrillar IAPP,and detailed cellular protein expression rescued by graphene quantum dots(GQDs),an IAPP inhibitor.We found that 29 proteins were significantly dysregulated by the IAPP species,while majority of these proteins were nucleotide-binding proteins.Collectively,our liquid chromatography tandem-mass spectrometry,fluorescence quenching,helium ion microscopy,cytotoxicity and discreet molecular dynamics simulations data revealed a remarkable capacity of GQDs in regulating aberrant protein expression through H-bonding and hydrophobic interactions,pointing to nanomedicine as a new frontier against human amyloid diseases.

Physical and toxicological profiles of human IAPP amyloids and plaques

Although much has been learned about the fibrillization kinetics, structure and toxicity of amyloid proteins, the properties of amyloid fibrils beyond the saturation phase are often perceived as chemically and biologically inert, despite evidence suggesting otherwise. To fill this knowledge gap, we examined the physical and biological characteristics of human islet amyloid polypeptide(IAPP) fibrils that were aged up to two months. Not only did aging decrease the toxicity of IAPP fibrils, but the fibrils also sequestered fresh IAPP and suppressed their toxicity in an embryonic zebrafish model. The mechanical properties of IAPP fibrils in different aging stages were probed by atomic force microscopy and sonication, which displayed comparable stiffness but age-dependent fragmentation, followed by self-assembly of such fragments into the largest lamellar amyloid structures reported to date. The dynamic structural and toxicity profiles of amyloid fibrils and plaques suggest that they play active, long-term roles in cell degeneration and may be a therapeutic target for amyloid diseases.