Human macrophage and dendritic cell-specific silencing of high-mobility group protein B1 ameliorates sepsis in a humanized mouse model

Abstract

Hypersecretion of cytokines by innate immune cells is thought to initiate multiple organ failure in murine models of sepsis. Whether human cytokine storm also plays a similar role is not clear. Here, we show that human hematopoietic cells are required to induce sepsisinduced mortality following cecal ligation and puncture (CLP) in the severely immunodeficient nonobese diabetic (NOD)/SCID/IL2Rγ −/− mice, and siRNA treatment to inhibit HMGB1 release by human macrophages and dendritic cells dramatically reduces sepsis-induced mortality. Following CLP, compared with immunocompetent WT mice, NOD/SCID/IL2Rγ −/− mice did not show high levels of serum HMGB1 or murine proinflammatory cytokines and were relatively resistant to sepsis-induced mortality. In contrast, NOD/SCID/IL2Rγ −/− mice transplanted with human hematopoietic stem cells [humanized bone marrow liver thymic mice (BLT) mice] showed high serum levels of HMGB1, as well as multiple human but not murine proinflammatory cytokines, and died uniformly, suggesting human cytokines are sufficient to induce organ failure in this model. Moreover, targeted delivery of HMGB1 siRNA to human macrophages and dendritic cells using a short acetylcholine receptor (AchR)-binding peptide [rabies virus glycoprotein (RVG)-9R] effectively suppressed secretion of HMGB1, reduced the human cytokine storm, human lymphocyte apoptosis, and rescued humanized mice from CLP-induced mortality. siRNA treatment was also effective when started after the appearance of sepsis symptoms. These results show that CLP in humanized mice provides a model to study human sepsis, HMGB1 siRNA might provide a treatment strategy for human sepsis, and RVG-9R provides a tool to deliver siRNA to human macrophages and dendritic cells that could potentially be used to suppress a variety of human inflammatory diseases.

HMGB1 may act via RAGE to promote angiogenesis in the later phase after intracerebral hemorrhage

“…# p < 0.001, ICH, EP, and FPS-ZM1 groups on day 14 vs. Sham group on day 14; p < 0.001, ICH group vs. EP group. et al, 2006;Qiu et al, 2008;Ye et al, 2012;Wang et al, 2014), and our work suggests it may likewise act as an early proinflammatory cytokine within the neurovascular unit to mediate inflammation during the acute phase of ICH (Lei et al, 2013b). On the other hand, HMGB1 appears to promote tissue recovery and remodeling at later stages following injury.…”

High Mobility Group Box Protein 1 (HMGB1): The Prototypical Endogenous Danger Molecule

“…Treatment with neutralizing monoclonal anti-HMGB1 antibodies ameliorates tissue injury and reduces lethality in this sepsis model (6). Recent studies confirmed that siRNA-specific knockdown of HMGB1 in macrophages and dendritic cells suppressed HMGB1 release, reduced the cytokine storm and rescued humanized mice from CLP sepsis-induced lethality (7).…”

Molecular mechanism and therapeutic modulation of high mobility group box 1 release and action: an updated review

“…In a more clinically relevant animal model of sepsis (induced by CLP), delayed administration of HMGB1-specific neutralizing antibodies, beginning 24 h after CLP, dose-dependently rescue rodents from lethal sepsis [20,74]. Moreover, targeted inhibition of HMGB1 expression in innate immune cells (e.g., macrophages and dendritic cells) reduces systemic HMGB1 accumulation, and similarly rescues mice from sepsis [76]. Taken together, these experimental data establish extracellular HMGB1 as a critical late mediator of experimental sepsis, which can be therapeutically targeted within wider therapeutic windows than other early cytokines.…”