NPT088 reduces both amyloid-b and tau pathologies in transgenic mice

Introduction: Alzheimer’s disease (AD) is characterized by appearance of both extracellular senile plaques and intracellular neurofibrillary tangles, comprised of aggregates of misfolded amyloid-b (Ab) and hyper-phosphorylated tau, respectively. In a previous study, we demonstrated that g3p, a capsid protein from bacteriophage M13, binds to and remodels misfolded aggregates of proteins that assume an amyloid conformation. We engineered a fusion protein (“NPT088”) consisting of the active fragment of g3p and human-IgG1-Fc. Methods: Aged Tg2576 mice or rTg4510 mice received NPT088 weekly via IP injection. Cognitive and/or functional motor endpoints were monitored during dosing. Pathology was quantified biochemically and immunohistochemically. Results: NPT088-lowered Ab plaque and improved cognitive performance of aged Tg2576 mice. Moreover, NPT088 reduced phospho-tau pathology, reduced brain atrophy, and improved cognition in rTg4510 mice. Discussion: These observations establish NPT088 as a novel therapeutic approach and potential drug class that targets both Ab and tau, the hallmark pathologies of AD

Lipid binding and membrane penetration of polymyxin B derivatives studied in a biomimetic vesicle system.

Understanding membrane interactions and cell-wall permeation of Gram-negative bacteria is of great importance, owing to increasing bacterial resistance to existing drugs and therapeutic treatments. Here we use biomimetic lipid vesicles to analyse membrane association and penetration by synthetic derivatives of polymyxin B (PMB), a potent naturally occurring antibacterial cyclic peptide. The PMB analogues studied were PMB nonapeptide (PMBN), in which the hydrophobic alkyl residue was cleaved, PMBN diastereomer containing D-instead of L-amino acids within the cyclic ring (dPMBN) and PMBN where the hydrophobic alkyl chain was replaced with an Ala6 repeat (Ala6-PMBN). Peptide binding measurements, colorimetric transitions induced within the vesicles, fluorescence quenching experiments and ESR spectroscopy were applied to investigate the structural parameters underlying the different membrane-permeation profiles and biological activities of the analogues. The experiments point to the role of negatively charged lipids in membrane binding and confirm the prominence of lipopolisaccharide (LPS) in promoting membrane association and penetration by the peptides. Examination of the lipid interactions of the PMB derivatives shows that the cyclic moiety of PMB is not only implicated in lipid attachment and LPS binding, but also affects penetration into the inner bilayer core. The addition of the Ala6 peptide moiety, however, does not significantly promote peptide insertion into the hydrophobic lipid environment. The data also indicate that the extent of penetration into the lipid bilayer is not related to the overall affinity of the peptides to the membrane

Neopeptide Antibiotics That Function as Opsonins and Membrane-Permeabilizing Agents for Gram-Negative Bacteria

We suggest a novel approach to enhancing antimicrobial drug action by utilizing engineered peptide conjugates. Our most potent conjugates, [fMLF]PMBN and [fMLF]PMEN, are nonapeptides derived from polymyxin B's (PMB's) cyclic moiety (Thr-Dab-cyclo[Dab-Dab-d-Phe-Leu-Dab-Dab-Thr], where Dab is 2,4-diaminobutyric acid) and polymyxin E's (PME's) cyclic moiety (Thr-Dab-cyclo[Dab-Dab-d-Leu-Leu-Dab-Dab-Thr]), respectively, attached to a linear tail comprised of formyl-Met-Leu-Phe (fMLF). The cyclic part binds to gram-negative lipopolysaccharides, rendering the bacterial outer membrane permeable to hydrophobic antibiotics. The tail confers chemotactic and opsonic activities upon the conjugates. These two activities appear to be the basis for the conjugates' antibacterial activities. The conjugates are 8 to 10 times less toxic than the parent PMB or PME antibiotics. Fourteen of 18 mice lethally challenged with erythromycin-resistant Klebsiella pneumoniae survived following intraperitoneal administration of erythromycin and [fMLF]PMBN, whereas erythromycin or the peptide conjugate alone had no effect. Moreover, the clearance of Klebsiella from blood was markedly enhanced by intravenous injection of the [fMLF]PMEN peptide conjugate compared to the clearance of the organism from the mice treated with buffer alone as a control and was similar to that achieved by the PME antibiotic. Blood clearance was also significantly enhanced by administration of PMEN either alone or in a mixture with fMLF, although the effect was less than that produced by the peptide conjugate. Since resistance to polymyxins, the parent molecules of the synthetic cyclic peptides, is rare, the emergence of bacteria resistant to the antimicrobial properties of the peptide conjugates may be precluded as well