University of Pittsburgh Environment & Occupational Health and Microbiology & Molecular Genetics, Pittsburgh, PA 15219

Berthony Deslouches 2018 research objectives update

AMP optimization, research objectives 2018

Research objectives 2018 update: My goals are (1) to develop peptide-based therapeutics against multidrug-resistant pathogens, (2) to investigate the impact of environmental toxicants on the microbiome and host-pathogen interactions, (3) to develop a global health program between University of Pittsburgh and Haiti related to the first two objectives (microbiome, combatting infections, etc.)

AMP optimization, research objectives 2018

. The human AMP LL37. Composed of 14 different amino acids arranged in an imperfect amphipathic helix (helical wheel), LL37 (as many other AMPs) has evolved to display multiple functions. Fitting the structural determinants of all these functions in a single molecule may limit the potential for complete optimization of antibiotic activity, which largely explains why AMP structure may not be as potent in biological matrices as conventional antibiotics. LL37 is currently in clinical trial as an anti-tumor agent delivered intratumorally12; µH, hydrophobic moment, a measure of amphipathicity. AMP limitations can be overcome by design optimization. (A) helical wheel projections of engineered AMPs LBU2, WLBU2, and WR12 modeled to form idealized amphipathic structures; MRSA was treated with LL37 and the indicated peptides in (B) phosphate buffer (PB) or (C) phosphate buffered saline (PBS) and bacterial counts in CFU/mL determined by dilution and growth on LB agar plates. LL37 displays similar activity in PB to LBU2 (B), made of just 2 amino acids (Arg and Val). However, LL37 and LBU2 are sensitive to saline (C). In sharp contrast, Trp-rich peptides WR12 and WLBU2 (derived from LBU2 by 3 Trp substitutions) are not affected by the presence of saline, proving that susceptibility to salt can be overcome by design optimization. Arrows indicate directions of µH.

Research objectives 2018: I have a rich multidisciplinary expertise in antimicrobial therapeutics, microbiology, biochemistry, immunology, toxicology, and pathology. This extensive experience enables me to address two different (although related) problems: multidrug resistance and the impact of environmental toxicants on the microbiome and host defense.
I previously investigated the structure-function relationship of antimicrobial peptides (AMPs) using de novo-engineered cationic AMPs (eCAPs) and demonstrated that AMP structure could be optimized to overcome many of the limitations of natural AMPs (e.g., reduced activity in acidic pH and serum salt concentrations). During my graduate and postdoctoral training, I enhanced the design of an initial series of Montelaro-engineered AMPs and demonstrated systemic efficacy against P. aeruginosa, using animal models of in vivo toxicity and sepsis treatment. The data led to six first-author papers in addition to over a dozen collaborative publications. Despite the success of these eCAPs, this was the first trial of optimization of the engineered AMPs, and these peptides are still being engineered mostly through trial and error. Considerable effort is required to completely investigate the potential of this new source of therapeutics. However, my vision goes far beyond the development of AMPs as antimicrobials as described in the following aims.
Aim 1. To establish a rational framework for the design of peptide-based therapeutics. I wish to establish a rational framework for peptide design for specific clinical applications against multidrug-resistant pathogens. I will expand AMP engineering to the design of peptide-based therapeutics of enhanced pharmacological properties with the goal to overcome hard-to-treat bacterial infections as well as viral and cancer disease. I intend to use biochemical methods to enhance their pharmacological properties using D-enantiomerization, cyclization, and “peptoidization” (e.g., shifting the amino acid side chain from the alpha to the adjacent or β-carbon). This aim will be supported by my new R01 award from NIGMS.
Aim 2. To elucidate the impact of environmental toxicants and antimicrobial therapeutics on the microbiome and host-pathogen interactions. This aim addresses the hypothesis that environmental toxicants have a combined effect on the host and the microbiota (including potential pathogens), which co-exist in the same ecosystem. Comparison of the impact of antibiotic and AMP therapy on the microbiome will be an important consideration. This work is in collaboration with the Center for Microbiome and Medicine.
Aim 3. To develop appropriate animal disease models addressing specific therapeutic applications and environmental impact on host defense. This aim establishes the connection between the first two objectives. To further advance the development of peptide-based therapeutics and examine the impact of environmental toxicants on the microbiome and host defense, I will seek to develop several animal models such as murine exposure to toxicants and/or respiratory pathogens as well as infection treatment models for specific applications (sepsis, trauma, or surgical site infections). I will seek a grant from the Department of Defense (DOD) to fund these specialized infection projects. I also have an interest in developing a global health program involving the University of Pittsburgh and Haiti as a long-term goal.

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