Targeting macrophage maladaptation for bacterial sepsis treatment

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Summary. Sepsis results in massive loss of life and places a significant economic burden on society. There are no effective treatments available for human sepsis other than antibiotics and life support. It is increasingly clear that sepsis is a bi-phasic process comprised of 1) an early high-energy demanding hyperinflammation state that can cause inflammatory shock and 2) a low energy supply immunosuppression state that promotes immunometabolic paralysis while countering oxidative damage. These two phases are seamlessly connected or even concurrent. This makes sepsis treatment extremely difficult, and many therapies such as anti- inflammatory corticosteroids often worsen the outcome. Macrophages (MΦs) play essential roles throughout the course of sepsis. In the hyperinflammation phase, MΦs sense pathogen-associated molecular patterns (PAMPs) through receptors such as toll-like receptors (TLRs) and NOD-, LRP-, and pyrin domain-containing protein 3 (NLRP3). MΦ NLRP3 inflammasome activation and resulting IL-1β secretion cause acute organ damage and release of damage-associate molecular patterns (DAMPs), which act back on the inflammatory pathways, forming a vicious cycle. Therefore, the MΦ NLRP3 inflammasome is a major contributor to the hyperinflammation phase of bacterial sepsis. Concomitant with inflammasome activation, MΦs undergo a broad cellular metabolic rewiring that favors glycolysis and turns mitochondria from ATP generation to reactive oxygen species (ROS) production, leading to mitochondrial oxidative stress, metabolic paralysis, and MΦ anergy in the immunosuppression phase. In addition, NLRP3 inflammasome activation results in GSDMD- mediated pyroptotic cell death (pyroptosis), directly removing MΦs from the fight against secondary infections. Recently, we identified that in MΦs, pyruvate dehydrogenase kinase 1 (PDHK1) plays a critical role in coordinating inflammasome activation and metabolic rewiring. In MΦs treated with LPS and ATP or Nigericin to stimulate inflammasome activation, dichloroacetate (DCA, a pyruvate analog and pan-PDHK inhibitor) or JX06 (a synthetic small-molecule and selective PDHK1 inhibitor) effectively suppressed IL-1β secretion and cell death, improved mitochondrial integrity, and reprogramed mitochondria from ROS production to ATP generation. In a mouse cecal ligation and puncture (CLP) model, PDHK inhibition significantly reduced plasma IL-1β levels. In this STTR Phase 1 project, we will test the hypothesis that JX06 can be developed as a novel therapy for bacterial sepsis. We propose two specific aims: SA1. To determine the toxicity of JX06 in cultured primary mouse and human cells in vitro and mice in vivo, and to study its pharmacokinetics in mice. SA2. To establish the effectiveness of JX06 in various mouse strains using the CLP model of sepsis. This STTR Phase 1 project will validate the role of MΦ PDHK1 in bacterial sepsis and provide a proof of concept to develop JX06 or its analog as a new therapeutic agent for bacterial sepsis. The successful completion of these proposed studies will serve as a milestone for the further development effort.