RAGE induces physiological activation of NADPH oxidase in neurons and astrocytes and neuroprotection.

The transmembrane receptor for advanced glycation end products (RAGE) is a signaling receptor for many damage- and pathogen-associated molecules. Activation of RAGE is associated with inflammation and an increase in reactive oxygen species (ROS) production. Although several sources of ROS have been previously suggested, how RAGE induces ROS production is still unclear, considering the multiple targets of pathogen-associated molecules. Here, using acute brain slices and primary co-culture of cortical neurons and astrocytes, we investigated the effects of a range of synthetic peptides corresponding to the fragments of the RAGE V-domain on redox signaling. We found that the synthetic fragment (60-76) of the RAGE V-domain induces activation of ROS production in astrocytes and neurons from the primary co-culture and acute brain slices. This effect occurred through activation of RAGE and could be blocked by a RAGE inhibitor. Activation of RAGE by the synthetic fragment stimulates ROS production in NADPH oxidase (NOX). This RAGE-induced NOX activation produced only minor decreases in glutathione levels and increased the rate of lipid peroxidation, although it also reduced basal and ß-amyloid induced cell death in neurons and astrocytes. Thus, specific activation of RAGE induces redox signaling through NOX, which can be a part of a cell protective mechanism.

Peptide ILE-GLU-TRP (Stemokin) Potential Adjuvant Stimulating a Balanced Immune Response.

Vaccines are widely used worldwide to prevent and protect from various infections. A variety of modern approaches to developing prophylactic and therapeutic vaccines is growing. In almost all cases, adjuvants are necessary to obtain an effective immune response.This work investigated the possibility of using the pharmaceutical peptide drug Stemokin as an adjuvant stimulating a balanced Th1/Th2 response.A study was conducted to compare the activity of Stemokin versus the approved adjuvant Alhydrogel in a murine vaccination model with the approved VAXIGRIP® vaccine.The first proof-of-concept experimental study shows that the peptide Ile-Glu-Trp has the adjuvant vaccine properties and anti-HA IgG2a enhancing response, revealing a Th1- favoring balanced Th1/Th2 immunomodulation.

Activation of RAGE leads to the release of glutamate from astrocytes and stimulates calcium signal in neurons.

The receptor for advanced glycation end products (RAGE) is a signal receptor first shown to be activated by advanced glycation end products, but also by a variety of signal molecules, including pathological advanced oxidation protein products and ß-amyloid. However, most of the RAGE activators have multiple intracellular targets, making it difficult to unravel the exact pathway of RAGE activation. Here, we show that the cell-impermeable RAGE fragment sequence (60-76) of the V-domain of the receptor is able to activate RAGE present on the plasma membrane of neurons and, preferentially, astrocytes. This leads to the exocytosis of vesicular glutamate transporter vesicles and the release of glutamate from astrocytes, which stimulate NMDA and AMPA/kainate receptors, resulting in calcium signals predominantly in neurons. Thus, we show a specific mechanism of RAGE activation by the RAGE fragment and propose a mechanism by which RAGE activation can contribute to the neuronal-astrocytic communication in physiology and pathology.

Immunization Against Specific Fragments of Neurotrophin p75 Receptor Protects Forebrain Cholinergic Neurons in the Olfactory Bulbectomized Mice.

Alzheimer's disease (AD) is characterized by progressive cognitive impairment associated with marked cholinergic neuron loss and amyloid-ß (Aß) peptide accumulation in the brain. The cytotoxicity in AD is mediated, at least in part, by Aß binding with the extracellular domain of the p75 neurotrophin receptor (p75NTR), localized predominantly in the membranes of acetylcholine-producing neurons in the basal forebrain. Hypothesizing that an open unstructured loop of p75NTR might be the effective site for Aß binding, we have immunized both olfactory bulbectomized (OBX) and sham-operated (SO) mice (n = 82 and 49, respectively) with synthetic peptides, structurally similar to different parts of the loops, aiming to block them by specific antibodies. OBX-mice have been shown in previous studies, and confirmed in the present one, to be characterized by typical behavioral, morphological, and biochemical AD hallmarks, including cholinergic deficits in forebrain neurons. Immunization of OBX- or SO-mice with KLH conjugated fragments of p75NTR induced high titers of specific serum antibodies for each of nine chosen fragments. However, maximal protective effects on spatial memory, evaluated in a Morris water maze, and on activity of choline acetyltransferase in forebrain neurons, detected by immunoreactivity to specific antibodies, were revealed only for peptides with amino acid residue sequences of 155-164 and 167-176. We conclude that the approach based on immunological blockade of specific p75NTR sites, linked with the cytotoxicity, is a useful and effective tool for study of AD-associated mechanisms and for development of highly selective therapy of cholinergic malfunctioning in AD patients.

Antibodies to a nonconjugated prion protein peptide 95-123 interfere with PrP( Sc ) propagation in prion-infected cells.

1. Vaccination-induced anti-prion protein antibodies are presently regarded as a promising approach toward treatment of prion diseases. Here, we investigated the ability of five peptides corresponding to three different regions of the bovine prion protein (PrP) to elicit antibodies interfering with PrP(Sc) propagation in prion-infected cells.2. Rabbits were immunized with free nonconjugated peptides. Obtained immune sera were tested in enzyme-linked immunosorbent assay (ELISA) and immunoblot for their binding to recombinant PrP and cell-derived pathogenic isoform (PrP(Sc)) and normal prion protein (PrP(c)), respectively. Sera positive in all tests were chosen for PrP(Sc) inhibition studies in cell culture.3. All peptides induced anti-peptide antibodies, most of them reacting with recombinant PrP. Moreover, addition of the serum specific to peptide 95-123 led to a transient reduction of PrP(Sc) levels in persistently prion-infected cells.4. Thus, anti-PrP antibodies interfering with PrP(Sc) propagation were induced with a prion protein peptide nonconjugated to a protein carrier. These results point to the potential application of the nonconjugated peptide 95-123 for the treatment of prion diseases.