Determining how neutrophil activities contribute to antibiotic treatment failure

Univ Of North Carolina Chapel Hill, Chapel Hill NC

Investigators

Abstract

The battle against bacterial infections is pivotal to modern medicine, allowing for safe medical procedures ranging from surgeries to organ transplants. However, despite the arsenal of effective antibiotics available, treatment failures persist in the absence of detectable antibiotic resistance, posing a significant challenge in the clinical management of diseases like Staphylococcus aureus bacteremia. S. aureus infections, despite showing in vitro sensitivity to common antibiotics such as vancomycin and daptomycin, often require prolonged treatments in vivo, with a substantial fraction of treatment failures attributed to poorly understood mechanisms of antibiotic tolerance. Our research aims to dissect the role of neutrophil extracellular traps (NETs) in promoting antibiotic tolerance in S. aureus. We hypothesize that NETs modulate bacterial metabolism, thereby enhancing bacterial survival against antibiotic treatments. We propose to explore the mechanisms underlying neutrophil-induced antibiotic tolerance and the potential therapeutic benefits of inhibiting NETosis through targeted interventions. This study is structured around two specific aims: First, we will delineate the mechanism through which neutrophils induce antibiotic tolerance in S. aureus. We will evaluate the role of NETosis in antibiotic tolerance using the NETosis inhibitor Cl-amidine and assess the contributions of various neutrophil effectors like DNA, calprotectin, myeloperoxidase, and antimicrobial peptides. Additionally, we will measure S. aureus metabolic responses such as ATP levels and respiratory activity in the presence of purified NETs. Second, we will investigate the impact of inhibiting neutrophilia and NETosis on the efficacy of antibiotics in a murine bacteremia infection model, using B6 mice treated with Anti-Ly6G antibodies to deplete neutrophils and PAD4-/- mice, deficient in NETosis. Furthermore, the effectiveness of dexamethasone in enhancing antibiotic clearance will be evaluated. Understanding the mechanisms that underlie antibiotic tolerance in vivo is crucial for addressing the high rates of treatment failure in bacterial infections. Our study aims to uncover the role of neutrophils and NETs in this context, potentially leading to novel therapeutic strategies that combine immunotherapy with traditional antimicrobial treatments to improve outcomes in bacterial infections. This could significantly impact clinical practices by reducing the duration of antibiotic therapies and reducing the evolution of antibiotic resistance.