Host Enzymes as Targets of Novel Host-Directed Antimicrobial Therapies
Abstract
In 2013, The Centers for Disease Control and Prevention released a list of 18 serious threats, and drug-resistant intracellular non-typhoidal Salmonella (NTS) was one of these threats. According to The World Health Organization, salmonellae account for the majority of cases of infectious diarrhea worldwide, leading to an estimated two million deaths annually. Infectious diarrheal diseases are often self-limiting, but they remain the second leading cause of death in children under 5 years old. However, multidrug-resistant invasive non-typhoidal Salmonella strains are a significant cause of concern not only for children, as invasive non-typhoidal Salmonella strains cause disease that has a case fatality reaching 25% in adults and children from the affected regions. Warfighters are also at high risk of contracting this infection, especially in Africa, or Southeast Asia, where there was a reported multidrug resistance (~20%), including last-resort among these strains. The US military personnel deployed in Thailand are affected by non-typhoidal strains, 94.6% of which are resistant to at least 1-2 antimicrobials. The emergence of multidrug-resistant strains indicates that both preventative and antimicrobial procedures need improvement. Hence, new antimicrobials are urgently needed, and we will address an existing gap in the lack of antimicrobial therapies against multidrug-resistant strains. Drugs directly targeting bacterial metabolic processes have been already extensively researched, but the novelty of our objective is to use inhibitors targeting host (mammalian) enzymes increasing bacterial killing by phagocytic cells, and develop entirely new therapies enhancing host-mediated clearance of bacteria, in other words, therapies “teaching” the host cell to kill bacteria better. Since pathogens rapidly evolve new mechanisms to counteract antibiotics affecting their physiology, our proposed approach is expected to be superior as it does not affect pathogens directly and therefore can escape the microbial resistance mechanisms. Here we will focus on the development of drugs targeting mammalian enzymes called DUBs, some which are already known as specific regulators of distinct processes related to protective responses to infections. We propose that there are multiple enzymes, as well as their inhibitors, which could be utilized in the design of this new therapy. As a proof of principle, in our pilot, we identified two promising candidate inhibitors, which are selective towards enzymes and stimulate almost complete clearance of bacteria from macrophages. The hypothesis and rationale are that once we identify small molecule drugs promoting bacterial clearance, we can apply this information to the development of antimicrobial therapeutics. The expected results will provide an identification of novel, likely synergistic, strategies to combat bacterial infections by targeting the host processes, consequently leading to increased bacterial clearance. In our proposed study, a combination of methodologies will be used to identify therapies enhancing the antimicrobial functions of macrophages. First, we will identify enzymatic targets in the infected host cell, which are (1) significantly modulated in the host upon infection with Salmonella (2) and which if absent increase the bactericidal properties of macrophage cells responsible for clearance of bacteria in the infected organism. Second, we will use high-throughput screens using drugs targeting the same family of enzymes, which lead to an increase in macrophage-mediated killing of bacteria without hurting the host cell. Select drugs will be tested in cellular and murine models in their ability to support clearance of a pathogen from infected animals and controlling inflammation and finally survival of an organism. Since bacteria use macrophages to hide from protective responses of the host and increase in numbers, the strategies targeting macrophage to perform its ant
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 10, 2021
- Source ID
- W81XWH2010176
Entities
People
- Mariola J. Ferraro
Organizations
- United States Army
- University of Florida