Therapeutical Administration of Peptide Pep19-2.5 and Ibuprofen Reduces Inflammation and Prevents Lethal Sepsis.

Sepsis is still a major cause of death and many efforts have been made to improve the physical condition of sepsis patients and to reduce the high mortality rate associated with this disease. While achievements were implemented in the intensive care treatment, all attempts within the field of novel therapeutics have failed. As a consequence new medications and improved patient stratification as well as a thoughtful management of the support therapies are urgently needed. In this study, we investigated the simultaneous administration of ibuprofen as a commonly used nonsteroidal anti-inflammatory drug (NSAID) and Pep19-2.5 (Aspidasept), a newly developed antimicrobial peptide. Here, we show a synergistic therapeutic effect of combined Pep19-2.5-ibuprofen treatment in an endotoxemia mouse model of sepsis. In vivo protection correlates with a reduction in plasma levels of both tumor necrosis factor α and prostaglandin E, as a likely consequence of Pep19-2.5 and ibuprofen-dependent blockade of TLR4 and COX pro-inflammatory cascades, respectively. This finding is further characterised and confirmed in a transcriptome analysis of LPS-stimulated human monocytes. The transcriptome analyses showed that Pep19-2.5 and ibuprofen exerted a synergistic global effect both on the number of regulated genes as well as on associated gene ontology and pathway expression. Overall, ibuprofen potentiated the anti-inflammatory activity of Pep19-2.5 both in vivo and in vitro, suggesting that NSAIDs could be useful to supplement future anti-sepsis therapies.

Peanut defensins: Novel allergens isolated from lipophilic peanut extract.

BACKGROUND: Peanut is one of the most hazardous sources of food allergens. Unknown allergens are still hidden in the complex lipophilic matrix. These allergens need to be discovered to allow estimation of the allergenic risk for patients with peanut allergy and to further improve diagnostic measures. OBJECTIVE: We performed detection, isolation, and characterization of novel peanut allergens from lipophilic peanut extract. METHODS: Extraction of roasted peanuts were performed under defined extraction conditions and examined by means of 2-dimensional PAGE. Subsequently, chromatographic methods were adapted to isolate low-molecular-weight components. Proteins were studied by using SDS-PAGE and immunoblotting with sera from patients with peanut allergy. For allergen identification protein sequencing, homology search and mass spectrometry were applied. Functional characterization for allergenicity was performed by using the basophil activation assay and for antimicrobial activity by using inhibition assays of different bacteria and fungi. RESULTS: IgE-reactive proteins of 12, 11, and 10 kDa were first detected after chloroform/methanol extraction in the flow through of hydrophobic interaction chromatography. The proteins were able to activate basophils of patients with peanut allergy. N-terminal sequencing and homology search in the expressed sequence tag database identified the allergens as peanut defensins, which was confirmed by using mass spectrometry. On microbial cell cultures, the peanut defensins showed inhibitory effects on the mold strains of the genera Cladosporium and Alternaria but none on bacteria. CONCLUSIONS: We identified defensins as novel peanut allergens (Ara h 12 and Ara h 13) that react in particular with IgE of patients with severe peanut allergy. Their antimicrobial activity is solely antifungal.

Protein reconstitution into freestanding planar lipid membranes for electrophysiological characterization.

The reconstitution of channel-forming proteins into planar lipid bilayers enables their functional characterization at very low (sometimes below attomolar) concentrations. We describe the three main approaches used in our laboratories (the Mueller-Rudin technique, in which the bilayers contain an organic solvent, the Montal-Mueller or solvent-free technique, and a method for membrane reconstitution via liposome formation), and we discuss their respective advantages and limitations. Despite the differences in the reconstitution procedures, subsequent protein characterization is based on the same electrophysiological technique. A transmembrane electric field is applied, inducing an ion current and allowing conclusions to be drawn on apparent pore sizes, or suggesting functional properties such as channel opening and closing upon ligand binding, pH-induced conformational changes, ion selectivity or substrate specificity.

New antiseptic peptides to protect against endotoxin-mediated shock.

Systemic bacterial infections are associated with high mortality. The access of bacteria or constituents thereof to systemic circulation induces the massive release of immunomodulatory mediators, ultimately causing tissue hypoperfusion and multiple-organ failure despite adequate antibiotic treatment. Lipid A, the "endotoxic principle" of bacterial lipopolysaccharide (LPS), is one of the major bacterial immunostimuli. Here we demonstrate the biological efficacy of rationally designed new synthetic antilipopolysaccharide peptides (SALPs) based on the Limulus anti-LPS factor for systemic application. We show efficient inhibition of LPS-induced cytokine release and protection from lethal septic shock in vivo, whereas cytotoxicity was not observed under physiologically relevant conditions and concentrations. The molecular mechanism of LPS neutralization was elucidated by biophysical techniques. The lipid A part of LPS is converted from its "endotoxic conformation," the cubic aggregate structure, into an inactive multilamellar structure, and the binding affinity of the peptide to LPS exceeds those of known LPS-binding proteins, such as LPS-binding protein (LBP). Our results thus delineate a novel therapeutic strategy for the clinical management of patients with septic shock.

Crucial roles of charged saccharide moieties in survival of gram negative bacteria against protamine revealed by combination of grazing incidence x-ray structural characterizations and Monte Carlo simulations.

Grazing incidence x-ray scattering techniques and Monte Carlo (MC) simulations are combined to reveal the influence of molecular structure (genetic mutation) and divalent cations on the survival of gram negative bacteria against cationic peptides such as protamine. The former yields detailed structures of bacterial lipopolysaccharide (LPS) membranes with minimized radiation damages, while the minimal computer model based on the linearized Poisson-Boltzmann theory allows for the simulation of conformational changes of macromolecules (LPSs and peptides) that occur in the time scale of ms. The complementary combination of the structural characterizations and MC simulation demonstrates that the condensations of divalent ions (Ca2+ or Mg2+) in the negatively charged core saccharides are crucial for bacterial survival.

The mode of action of the lantibiotic lacticin 3147--a complex mechanism involving specific interaction of two peptides and the cell wall precursor lipid II.

Lacticin 3147 is a two-peptide lantibiotic produced by Lactococcus lactis in which both peptides, LtnA1 and LtnA2, interact synergistically to produce antibiotic activities in the nanomolar concentration range; the individual peptides possess marginal (LtnA1) or no activity (LtnA2). We analysed the molecular basis for the synergism and found the cell wall precursor lipid II to play a crucial role as a target molecule. Tryptophan fluorescence measurements identified LtnA1, which is structurally similar to the lantibiotic mersacidin, as the lipid II binding component. However, LtnA1 on its own was not able to substantially inhibit cell wall biosynthesis in vitro; for full inhibition, LtnA2 was necessary. Both peptides together caused rapid K(+) leakage from intact cells; in model membranes supplemented with lipid II, the formation of defined pores with a diameter of 0.6 nm was observed. We propose a mode of action model in which LtnA1 first interacts specifically with lipid II in the outer leaflet of the bacterial cytoplasmic membrane. The resulting lipid II:LtnA1 complex is then able to recruit LtnA2 which leads to a high-affinity, three-component complex and subsequently inhibition of cell wall biosynthesis combined with pore formation.