Blocking Multiple Pathological Factors for Sepsis Treatment

About This Grant

ABSTRACT Sepsis and septic shock are leading causes of death in hospitals, contributing to 20% of global deaths. Sepsis is a syndrome of infection that is primarily bacterial, and patients typically receive broad-spectrum antibiotics to combat the infection. However, relying solely on antibacterial treatments proves insufficient, particularly for late- stage sepsis, as bacterial endotoxins such as lipopolysaccharide (LPS) and lipoteichoic acid persist within the host. These endotoxins serve as the main drivers of sepsis by triggering toll-like receptor (TLR)-mediated inflammation. It is well recognized that TLR-4, which interacts with LPS from bacteria, plays a significant role in mediating the progression of sepsis, leading to a strong emphasis on inhibiting TLR-4 activation as a primary focus for sepsis treatment. However, in addition to TLR-4, several other TLRs, such as TLR-2 and TLR-5, are also involved in driving bacterial sepsis. Therefore, solely blocking TLR-4 activation may not be sufficient to effectively treat sepsis, which could explain the lack of success in clinical trials of TLR-4 antagonists such as TAK-242 and Eritoran. Thus, addressing multiple TLR-mediated pathological pathways concurrently in sepsis treatment is imperative. This proposal aims to develop a nanoparticle-based therapy that simultaneously inhibits multi-TLR activation and neutralizes bacterial infections. AN-3485, a potent multi-TLR inhibitor, has not yet been fully explored for sepsis treatment. The hydrophobic nature, which results in poor aqueous solubility, also limits its application in systemic administration. The application of polymyxin B (PMB), a critical last-resort antibiotic for sepsis treatment, has been severely limited by dose-dependent toxicity. We hypothesize that co-encapsulation of AN- 3485 and PMB within polymerized tannic acid (pTA) nanoparticles will: (1) enhance AN-3485’s solubility, enabling systemic delivery; (2) mitigate PMB toxicity while preserving its antibacterial activity; and (3) synchronize drug biodistribution at inflammation sites, thereby maximizing therapeutic efficacy. Our preliminary studies demonstrate that pTA/AN-3485/PMB nanoparticles significantly reduce cytotoxicity, improve in vivo tolerability, inhibit multi-TLR activation, suppress bacterial growth, and achieve 100% survival in an LPS-induced endotoxemia murine model. Building on this proof of concept, we seek to further explore the mechanistic basis of its therapeutic effects. To achieve these goals, we propose two specific aims: 1) Determine the safety, pharmacokinetics (PK), and biodistribution (BD) of pTA/AN-3485/PMB; and 2) Evaluate the therapeutic efficacy of pTA/AN-3485/PMB in Endotoxin- and Polymicrobial-induced sepsis models. The success of our research has the potential to contribute to the development of a new medicine for sepsis, aiming to mitigate the ongoing high mortality rates associated with sepsis.