Biology subjects

Wagner, N. J.

Publications and source records attributed to Wagner, N. J..

4 recordsLinked to original sources

bioRxiv2025

The innate immune protein calprotectin incapacitates the bactericidal activity of β-lactam antibiotics

{beta}-lactam antibiotics are widely used to treat bacterial infections, yet treatment failures frequently occur even without resistance. Here, we show that the innate immune protein calprotectin (CP), released by neutrophils and abundant at infection sites, induces tolerance to {beta}-lactam antibiotics in Staphylococcus aureus. CP is a potent zinc chelator and was found to inhibit the activity of S. aureus autolysins, zinc-dependent enzymes essential for bacterial lysis following {beta}-lactam-mediated inhibition of cell wall synthesis. This protection was independent of bacterial growth or metabolism and was specific to {beta}-lactam antibiotics. Mechanistically, CP inactivated the amidase activity of Atl, the major S. aureus autolysin, through zinc sequestration. In vivo, oxacillin was significantly more effective in CP-deficient mice, demonstrating that CP reduces {beta}-lactam efficacy during infection. These findings reveal a host-derived mechanism of antibiotic tolerance and suggest that zinc availability at infection sites may directly influence {beta}-lactam treatment outcomes.

microbiology↗

bioRxiv2024

A host-directed adjuvant resuscitates and sensitizes intracellular bacterial persisters to antibiotics

There are two major problems in the field of antimicrobial chemotherapy-antibiotic resistance and antibiotic tolerance. In the case of antibiotic tolerance, antibiotics fail to kill the bacteria as their phenotypic state affords them protection from the bactericidal activity of the antibiotic. Antibiotic tolerance can affect an entire bacterial population, or a subset of cells known as persister cells. Interaction with the host induces the formation of persister cells in numerous pathogens, with reactive oxygen and nitrogen species production being heavily implicated in the collapse of bacterial energy levels and entrance into an antibiotic tolerant state. Here, we developed a high-throughput screen to identify energy modulators for intracellular Staphylococcus aureus. The identified compound, KL1, increases intracellular bacterial energy and sensitizes the persister population to antibiotics, without causing cytotoxicity or bacterial outgrowth. We demonstrate that KL1 exhibits adjuvant activity in a murine model of S. aureus bacteremia and intracellular infection of Salmonella Typhimurium. Transcriptomic analysis and further studies on its mechanism of action reveal that KL1 modulates host immune response genes and suppresses the production of reactive species in host macrophages, alleviating one of the major stressors that induce antibiotic tolerance. Our findings highlight the potential to target intracellular persister cells by stimulating their metabolism and encourage larger efforts to address antibiotic tolerance at the host-pathogen interface, particularly within the intracellular milieu.

microbiology↗

bioRxiv2022

Inflammasome-mediated glucose limitation induces antibiotic tolerance in Staphylococcus aureus

Staphylococcus aureus is a leading human pathogen that frequently causes relapsing infections. Host-pathogen interactions have been shown to have substantial impacts on antibiotic susceptibility and the formation of antibiotic tolerant cells. In this study, we interrogate how a major S. aureus virulence factor, -toxin, interacts with macrophages to alter the microenvironment of the pathogen, thereby influencing its susceptibility to antibiotics. We find -toxin-mediated activation of the NLRP3 inflammasome induces antibiotic tolerance in the host cell cytoplasm. Induction of antibiotic tolerance is driven by increased glycolysis in the host cells, resulting in glucose limitation and ATP depletion in S. aureus. Additionally, inhibition of NLRP3 activation improves antibiotic efficacy in vitro and in vivo. Our findings identify interactions between S. aureus and the host that result in metabolic crosstalk that can determine the outcome of antimicrobial therapy.

microbiology↗

bioRxiv2021

Macrophage-produced peroxynitrite induces antibiotic tolerance and supersedes intrinsic mechanisms of persister formation

Staphylococcus aureus is a leading human pathogen that frequently causes chronic and relapsing infections. Antibiotic tolerant persister cells contribute to frequent antibiotic failure in patients. Macrophages represent an important niche during S. aureus bacteremia and recent work has identified a role for oxidative burst in the formation of antibiotic tolerant S. aureus. We find that host-derived peroxynitrite, the reaction product of superoxide and nitric oxide, is the main mediator of antibiotic tolerance in macrophages. Using a collection of S. aureus clinical isolates, we find that, despite significant variation in persister formation in pure culture, all strains were similarly enriched for antibiotic tolerance following internalization by activated macrophages. Our findings suggest that host interaction strongly induces antibiotic tolerance and may negate bacterial mechanisms of persister formation, established in pure culture. These findings emphasize the importance of studying antibiotic tolerance in the context of bacterial interaction with the host suggest that modulation of the host response may represent a viable therapeutic strategy to sensitize S. aureus to antibiotics.

microbiology↗