Bactericidal action of tachyplesin I against oral streptococci

Tachyplesin I and its derivatives: A pharmaco-chemical perspective on their antimicrobial and antitumor potential

INTRODUCTION

Increasing evidence suggests that intratumor microbiota are an intrinsic component in the tumor microenvironment across multiple cancer types, and that there is a close relationship between microbiota and tumor progression. Therefore, how to address the interaction between bacteria and malignances has become a growing concern. Tachyplesin I (TPI), a peptide with dual antimicrobial and antitumor effects, holds great promise as a therapeutic alternative for the aforementioned diseases, with the advantage of broad-spectrum activities, quick killing efficacy, and a low tendency to induce resistance.

AREAS COVERED

This review comprehensively summarizes the pharmacological mechanisms of TPI with an emphasis on its antimicrobial and antitumor potential. Furthermore, it presents advances in TPI derivatives and gives a perspective on their future development. The article is based on literature searches using PubMed and SciFinder to retrieve the most up-to-date information of TPI.

EXPERT OPINION

Bacterial infections and cancer both pose a serious threat to health due to their symbiotic interactions and drug resistance. TPI is anticipated to be a novel agent to control pathogenic bacteria and various tumors through multiple mechanisms of action. Indeed, the continuous advancements in chemical modification and innovative applications of TPI give hope for future improvements in therapeutic efficacy.

Genomic and functional analysis of the toxic effect of tachyplesin I on the embryonic development of zebrafish

Tachyplesin I (TP I) is an antimicrobial peptide isolated from the hemocytes of the horseshoe crab. With the developments of DNA microarray technology, the genetic analysis of the toxic effect of TP I on embryo was originally considered in our recent study. Based on our microarray data of the embryonic samples of zebrafish treated with the different doses of TP I, we performed a series of statistical data analyses to explore the toxic effect of TP I at the genomic level. In this paper, we first employed the hexaMplot to illustrate the continuous variation of the gene expressions of the embryonic cells treated with the different doses of TP I. The probabilistic model-based Hough transform was used to classify these differentially coexpressed genes of TP I on the zebrafish embryos. As a result, three line rays supported with the corresponding 174 genes were detected in our analysis. Some biological processes of the featured genes, such as antigen processing, nuclear chromatin, and structural constituent of eye lens, were significantly filtered with the smaller P values.

Beta-sheet antibiotic peptides as potential dental therapeutics

Small, cysteine-rich, beta-sheet peptide antibiotics are found throughout the Animalia. Though broad spectrum in potential, they may exert selective antimicrobial effects under certain conditions. We have explored the antimicrobial properties of two families of beta-sheet peptide antibiotics, defensins and protegrins, against periodontopathic bacteria. The rabbit defensin NP-1 was active against facultative Gram-negative bacteria associated with early onset periodontitis, including Actinobacillus actinomycetemcomitans and the Capnocytophaga spp. Porcine protegrins showed even greater activity against those organisms, as well as against anaerobic bacteria associated with adult periodontitis, including Porphyromonas gingivalis Prevotella intermedia and Fusobacterium nucleatum. Based on these observations, we believe that protegrin-like beta-sheet peptide antibiotics may be useful dental therapeutics.

Killing of Fusobacterium nucleatum, Porphyromonas gingivalis and Prevotella intermedia by protegrins

Protegrins are broad spectrum antibiotic peptides isolated from porcine leukocytes. In this study, we (i) examine the sensitivity of Gram-negative, anaerobic periodontal pathogens to synthetic protegrins; (ii) determine the relative potencies of protegrin congeners against these bacteria; and (iii) compare the potency of protegrins with other antibiotic peptides, including magainin MSI-78, tachyplesin I, cecropin P1, human defensins HNP-1-3, and clavanin A. Synthetic L- and D-enantiomers of protegrin 1 (PG-1 and D-PG-1, respectively), and L-enantiomers of protegrins 2, 3 and 5 (PG-2, PG-3 and PG-5) were tested against Fusobacterium nucleatum, and black-pigmented organisms including Porphyromonas gingivalis and Prevotella intermedia. Strains of both F. nucleatum and the black-pigmented organisms were sensitive to PG-1, and exhibited mean ED99 of 2.2-2.3 micrograms/ml and 3.4-9.9 micrograms/ml, respectively. The D-form was statistically more potent than the L-form against these oral anaerobes, and although this difference in potency is unlikely to be of decisive therapeutic significance, the D-form may be of value given ability to resist microbial and host-derived proteases. PG-1 was more potent than magainin, tachyplesin, cecropin, defensins and clavanin under test conditions. Hypertonic salt concentrations and heat-inactivated serum were found to be inhibitory to the bactericidal activity of PG-1. PG-1 was found to induce morphologic alterations in the ultrastructural appearance of F. nucleatum consistent with damage to the bacterial membranes. We conclude that protegrins may be useful antimicrobial agents in therapy against Gram-negative anaerobic bacteria believed to be involved in chronic, adult forms of periodontal infections.

Sensitivity of periodontal pathogens to the bactericidal activity of synthetic protegrins, antibiotic peptides derived from porcine leukocytes

Protegrins, small peptides (1900 to 2160 daltons) isolated from porcine leukocytes, are bactericidal against a broad range of medical pathogens in vitro under conditions which reflect the extracellular milieu. The purpose of this study was to determine whether Gram-negative, facultative periodontal pathogens were sensitive to the protegrins. Synthetic L- and D-enantiomers of protegrin 1 (PG-1 and D-PG-1, respectively), and L-enantiomers of protegrins 2, 3, and 5 (PG-2, PG-3, and PG-5) were tested against Actinobacillus actinomycetemcomitans (three strains) and Capnocytophaga spp. (three strains). Strains of both A. actinomycetemcomitans and Capnocytophaga spp. were sensitive to PG-1, and exhibited ED99 (dose at which 99% killing was observed after 1 hr at 37 degrees C) of 0.5 to 3 microg/mL and 4 to 19 microg/mL, respectively. The D-form and the L-form were equally effective. Serum (above 5% v/v) inhibited the bactericidal effects of 10 microg/mL PG-1, but the inhibitory effect was overcome by concentrations of PG-1 at 100 microg/mL. Different patterns of sensitivity were observed when the effects of PG-1, D-PG-1, PG-2, PG-3, and PG-5 were compared against A. actinomycetemcomitans and the Capnocytophaga. We conclude that protegrins may be useful antimicrobial agents in therapy against periodontal infections.