Novel synthetic peptides with antimicrobial and endotoxin neutralizing properties for management of the sepsis syndrome

Abstract

A peptide with an amino acid composition such that the peptide is amphipathic, cationic and forms a stable alpha-helix and has the following structure comprising at least 12 amino acids R1-R2-A1-B1-(A2-B2-C1-A3)m-(C2)n-R3, wherein A=an amino acid selected from the basic amino acids Lys,Arg or His B=an amino acid selected from the aromatic amino acids Phe, Trp or Tyr C=an amino acid selected from the group comprising the hydrophobic amino acids Leu, Ile, Val or Ala, and said peptide has either the orientation according to the formula or the retro orientation thereof, wherein at least 0-n of the repetitive sequence motifs (A2-B2-C1-A3) have the retro orientation and the remaining repetitive motifs (A2-B2-C1-A3) have the orientation as presented in the formula and wherein, R1-R2- and R3 are a number of amino acids, and wherein m=1-10, preferably 2-8, more preferably 2-5 and n=1-3, a pharmaceutical composition comprising such a peptide application thereof in treatment or diagnosis related to i.a. parasite infection topical and systemic tumors and septic shock.

Description

[0001] Bacterial infections as a complication of surgery, prolonged hospitalization, accidents and other traumatic events, may lead to serious clinical symptoms such as sepsis, septic shock, inadequate organ perfusion, multiple organ failure and acute respiratory distress syndrome (ARDS). Despite advances in medicine over the past decade, an increase in the incidence of sepsis is evident with a mortality rate of 20 to 80%. The sepsis syndrome is initiated when micro-organisms bypass the natural defensive barriers of the body, such as skin and mucous membranes. If the immune system is unable to arrest the infection locally, the organism or its toxins may invade the circulation, where specific bacterial products elicit an inflammatory response that leads to the activation of an array of plasma proteins and cellular defense systems. Although mobilisation of the defence systems of the host is of paramount importance in combatting invading organisms, a cascade of events may simultaneousl...

AI Technical Summary

Benefits of technology

The patent describes a new generation of peptides that can bind to lipopolysaccharide (LPS), a component of bacteria that causes septic shock. These peptides have been designed using molecular modelling and have specific properties such as being small, soluble, and low in toxicity. The peptides can be made using solid-state chemistry and have been shown to have strong anti-microbial activities against both Gram-positive and Gram-negative bacteria. They can also bind to LPS with high affinity, precipitate it from solution, and detect it at low concentrations. The peptides can also neutralize endotoxin-mediated cytokine production and prevent septic shock in mice challenged with lethal doses of endotoxin or live pathogenic bacteria.

Problems solved by technology

Bacterial infections as a complication of surgery, prolonged hospitalization, accidents and other traumatic events, may lead to serious clinical symptoms such as sepsis, septic shock, inadequate organ perfusion, multiple organ failure and acute respiratory distress syndrome (ARDS).

Although mobilisation of the defence systems of the host is of paramount importance in combatting invading organisms, a cascade of events may simultaneously be triggered that can lead to irreversible tissue injury and organ dysfunction.

Persistent stimulation of the cellular defence system by excessive LPS leads to overproduction of cytokines which activate a cascade of secondary inflammatory mediators eventually leading to blood vessel damage, circulatory and metabolic disturbances.

Clinically significant endotoxemia may go undetected by the currently available endotoxin assay, the Limulus amoebocyte lysate assay or LAL test, which has been shown to have serious limitations relating to sensitivity as well as to interference by plasma factors.

Current therapeutic options for Gram-negative bacterial sepsis are limited to anti microbial agents, hemodynamic support and management of sepsis-induced organ dysfunction.

Although conventional antibiotic therapy is effective in halting the proliferation of susceptible micro-organisms, the massive release of LPS into the circulation by damaged bacteria may aggravate a septic episode.

Extensive clinical use of conventional antibiotics such as penicillins, cephalosporins and the like, in the treatment of bacterial infections during the past three decades, has resulted in a dramatic reduction in the efficacy of antibiotic therapy due to an alarming increase in the number of multi-drug-resistant bacteria.

Efforts to intervene directly in the pathophysiological mechanisms which underlie the septic process have yielded inconsistent and largely disappointing results.

Anti-endotoxin monoclonal antibodies, anti-cytokine therapies and other anti-inflammatory strategies have proven not to be of sufficient benefit to warrant approval as standard adjunctive therapies for human sepsis.

Disruption of the cross-linkages, by displacement of these cations with positively charged entities of high affinity for LPS, was postulated to result in membrane destabilization.

PmB and LALF detoxify LPS in vitro and afford protection against endotoxin-mediated lethality in experimental animals, but toxicity precludes their clinical use against Gram-negative bacterial infections.

The CAP18 protein inhibits LPS responses in vitro but currently available data are not sufficient for assessment as a potential therapeutic agent in the treatment of sepsis.

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