Synthesis and characterization of a novel inhibitor of C-reactive protein-mediated proinflammatory effects

A novel phosphocholine-mimetic inhibits a pro-inflammatory conformational change in C-reactive protein

C-reactive protein (CRP) is an early-stage acute phase protein and highly upregulated in response to inflammatory reactions. We recently identified a novel mechanism that leads to a conformational change from the native, functionally relatively inert, pentameric CRP (pCRP) structure to a pentameric CRP intermediate (pCRP*) and ultimately to the monomeric CRP (mCRP) form, both exhibiting highly pro-inflammatory effects. This transition in the inflammatory profile of CRP is mediated by binding of pCRP to activated/damaged cell membranes via exposed phosphocholine lipid head groups. We designed a tool compound as a low molecular weight CRP inhibitor using the structure of phosphocholine as a template. X-ray crystallography revealed specific binding to the phosphocholine binding pockets of pCRP. We provide in vitro and in vivo proof-of-concept data demonstrating that the low molecular weight tool compound inhibits CRP-driven exacerbation of local inflammatory responses, while potentially preserving pathogen-defense functions of CRP. The inhibition of the conformational change generating pro-inflammatory CRP isoforms via phosphocholine-mimicking compounds represents a promising, potentially broadly applicable anti-inflammatory therapy.

Unraveling the Antioxidant, Binding and Health-Protecting Properties of Phenolic Compounds of Beers with Main Human Serum Proteins: In Vitro and In Silico Approaches

Our recently published in vivo studies and growing evidence suggest that moderate consumption of beer possesses several health benefits, including antioxidant and cardiovascular effects. Although beer contains phenolic acids and flavonoids as the major composition, and upon consumption, the levels of major components increase in the blood, there is no report on how these beer components interact with main human serum proteins. Thus, to address the interaction potential between beer components and human serum proteins, the present study primarily aims to investigate the components of beer from different industrial sources as well as their mode of interaction through in silico analysis. The contents of the bioactive compounds, antioxidant capacities and their influence on binding properties of the main serum proteins in human metabolism (human serum albumin (HSA), plasma circulation fibrinogen (PCF), C-reactive protein (CRP) and glutathione peroxidase 3 (GPX3)) were studied. In vitro and in silico studies indicated that phenolic substances presented in beer interact with the key regions of the proteins to enhance their antioxidant and health properties. We hypothesize that moderate consumption of beer could be beneficial for patients suffering from coronary artery disease (CAD) and other health advantages by regulating the serum proteins.

Synthetic Peptide Libraries: From Random Mixtures to In Vivo Testing

Combinatorially generated molecular repertoires have been largely used to identify novel bioactive compounds. Ever more sophisticated technological solutions have been proposed to simplify and speed up such process, expanding the chemical diversity space and increasing the prospect to select new molecular entities with specific and potent activities against targets of therapeutic relevance. In this context, random mixtures of oligomeric peptides were originally used and since 25 years they represent a continuous source of bioactive molecules with potencies ranging from the sub-nM to microM concentration. Synthetic peptide libraries are still employed as starting "synthetic broths" of structurally and chemically diversified molecular fragments from which lead compounds can be extracted and further modified. Thousands of studies have been reported describing the application of combinatorial mixtures of synthetic peptides with different complexity and engrafted on diverse structural scaffolds for the identification of new compounds which have been further developed and also tested in in vivo models of relevant diseases. We briefly review some of the most used methodologies for library preparation and screening and the most recent case studies appeared in the literature where compounds have reached at least in vivo testing in animal or similar models. Recent technological advancements in biotechnology, engineering and computer science have suggested new options to facilitate the discovery of new bioactive peptides. In this instance, we anticipate here a new approach for the design of simple but focused tripeptide libraries against druggable cavities of therapeutic targets and its complementation with existing approaches.

Peptides and Peptide Analogs to Inhibit Protein-Protein Interactions

Protein-protein interactions are governed by relatively few amino acid residues at the binding interface. Peptides derived from these protein regions may serve as mimics of one of the interaction partners in structural studies or as inhibitors to disrupt the respective interaction and investigate its biological consequences. Inhibitory peptides may also be lead structures for drug development if the respective protein-protein interaction is essential for a pathogen or disease mechanism. Binding peptides may be systematically derived from one of the binding partners or found in the screen of combinatorial peptide libraries. Molecular modelling based on structural data helps to refine existing peptides or even design novel binding peptides. This chapter gives an outline of the binding peptide discovery process and subsequent chemical modifications to further enhance affinity and specificity and to increase stability against degradation in vivo. Examples from the past three decades illustrate the great diversity of applications for protein binding peptides and peptide analogs.

A novel peptide inhibitor attenuates C-reactive protein's pro-inflammatory effects in-vivo

BACKGROUND

Higher levels of C-reactive protein (CRP) predict cardiovascular events and also portend a poorer prognosis in patients with acute coronary syndromes. Much in-vitro and in-vivo data support a role for CRP in atherogenesis.

METHODS

Using the one-bead-one-compound (OBOC) combinatorial library method we have successfully identified peptides against human CRP that inhibit its biological effects in-vitro. Hence we tested the effect of the best characterized inhibitor (CRP-i2) on the effects of CRP in an appropriate animal model, Wistar rats.

RESULTS

Treatment with CRP resulted in significant increase in superoxide anion, nuclear factor kappaB (NFκb) activity and the release of biomarkers of inflammation from macrophages compared to Wistar rats treated with human albumin (HuSA). Pre-treatment with the inhibitor, CRP-i2, resulted in a significant reduction in CRP induced superoxide anion, NFκb activity and biomarkers of inflammation. Also, there were no observed clinical or laboratory related adverse effects.

CONCLUSIONS

We demonstrate that our novel peptide inhibitor attenuates the proinflammatory effects of CRP in-vivo. Future studies will examine the long-term effects of this inhibitor on vascular pathobiology.