Evaluation of WLBU2 Peptide and 3- O -Octyl- sn -Glycerol Lipid as Active Ingredients for a Topical Microbicide Formulation Targeting Chlamydia trachomatis

Abstract

Topical microbicides for prevention of sexually transmitted diseases (STDs) would be especially useful for women who are not able to persuade their partner(s) to take precautions. Many topical microbicides are in various stages of development, based on a variety of active ingredients. We investigated the in vitro activity of an engineered antimicrobial peptide (WLBU2) and a lipid (3-O-octyl-sn-glycerol [3-OG]) which could potentially be used as active ingredients in such a product. Using commercially available cytotoxicity reagents [Alamar Blue, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), and lactate dehydrogenase (LDH)], we first determined the toxicity of WLBU2 and 3-OG to the host cells in our assay procedure and excluded toxic concentrations from further testing. To determine activity against Chlamydia trachomatis, we used an assay previously developed by our laboratory in which chlamydial elementary bodies (EBs) were exposed to microbicides prior to contact with epithelial cells: the minimum (microbi)cidal concentration (MCC) assay. To further simulate conditions of transmission, we carried out the same assay in the presence of a simulated vaginal fluid, a simulated seminal fluid, human serum albumin, and a range of pH values which might be found in the human vagina at the time of exposure. Last, we tested WLBU2 and 3-OG in combination to determine if adding them together resulted in synergistic activity. We found that WLBU2 and 3-OG both have excellent activity in vitro against C. trachomatis and significantly more activity when added together. The simulated fluids reduced activity, but the synergy seen is good evidence that they would be effective when combined in a microbicide formulation.

Comparative functional properties of engineered cationic antimicrobial peptides consisting exclusively of tryptophan and either lysine or arginine

“…In the last two decades, our laboratory has focused on rationally engineering AMPs to overcome intrinsic limitations of natural AMPs (Tencza et al, 1999;Phadke et al, 2002;Deslouches et al, 2005;Skinner et al, 2010Steckbeck et al, 2014. Hence, we previously reported the rational design of an optimized engineered cationic antimicrobial peptide (eCAP) series consisting exclusively of arginine and tryptophan residues (WR series) that display broad activity against a diverse spectrum of Grampositive and Gram-negative bacteria, including extensively drug-resistant (XDR) strains (Deslouches et al, 2013).…”

Development of a liposome microbicide formulation for vaginal delivery of octylglycerol for HIV prevention

“…Octylglycerol (OG), a synthetic lipid derived from lipids in human breast milk developed by Dr. Charles Isaacs at the Institute for Basic Research in Developmental Disabilities (Staten Island, NY), has been shown to have potential as a vaginal and rectal microbicide 12,13,16,17 . This compound destabilized viral envelopes and the membranes of pathogenic bacteria and fungi and inactivated HIV, HSV, gonorrhoeae, and Trichomonas without harming Lactobacillus.…”

Building a working understanding of protein adsorption with model systems and serendipity

“…The 24-residue WLBU2 peptide has been optimized specifically for formation of amphiphilic helix conformation in the presence of counterions, membrane-mimetic solvents, and bacterial membranes [73][74][75][76]. We compared the behavior of WLBU2 at uncoated and PEO-coated surfaces with that of other similarly sized, synthetic peptides (poly-glutamic acid, poly-lysine, poly-arginine, and a peptide chemically identical to WLBU2 but possessing a scrambled amino acid sequence).…”