Abstract
The pathophysiology of sepsis is characterized by a systemic inflammatory response to infection; however, the cytokine blockade that targets a specific early inflammatory mediator, such as tumor necrosis factor, has shown disappointing results in clinical trials. During sepsis, excessive endotoxins are internalized into the cytoplasm of immune cells, resulting in dysregulated pyroptotic cell death, which induces the leakage of late mediator alarmins such as HMGB1 and PTX3. As late mediators of lethal sepsis, overwhelming amounts of alarmins bind to high-affinity TLR4/MD2 and low-affinity RAGE receptors, thereby amplifying inflammation during early-stage sepsis. In this study, we developed a novel alarmin/receptor-targeting system using a TLR4/MD2/RAGE-blocking peptide (TMR peptide) derived from the HMGB1/PTX3-receptors interacting motifs. The TMR peptide successfully attenuated HMGB1/PTX3- and LPS-mediated inflammatory cytokine production by impairing its interactions with TLR4 and RAGE. Moreover, we developed TMR peptide-conjugated liposomes (TMR-Lipo) to improve the peptide pharmacokinetics. In combination therapy, moderately antibiotic-loaded TMR-Lipo demonstrated a significant therapeutic effect in a mouse model of cecal ligation- and puncture-induced sepsis. The identification of these peptides will pave the way for the development of novel pharmacological tools for sepsis therapy.