Sepsis affects more than 800,000 people annually with a mortality rate as high as 30% in the US. Severe sepsis complicated with multiple organ dysfunction syndrome (MODS) is a leading cause of death in intensive therapy units with a mortality rate exceeding 50%. Acute lung injury (ALI) is an important component of MODS and often serves as a direct cause of patient death. Nonetheless, few effective therapeutic targets have been identified that predispose an individual to MODS and ALI in sepsis. Alveolar macrophages (AM) are at the center of the pathogenesis of ALI triggered by sepsis. Macrophage (M?pyroptosis is a recently identified caspase-1-dependent programmed cell death, which features rapid plasma-membrane rupture and release of pro-inflammatory intracellular contents. However, the in vivo role of M?yroptosis in the progression of sepsis and the mechanism underlying M?yroptosis remain unclear. We now demonstrate in our preliminary studies that sepsis induces AM and circulating monocytes pyroptosis in a mouse polymicrobial sepsis model of cecal ligation and puncture (CLP). This sepsis-induced pyroptosis is mediated by a novel signaling pathway, in which (RAGE)-dependent endocytosis of HMGB1) activates pyroptosome assembly and cell pyroptosis. Our further observations suggest that induction of AM pyroptosis enhances inflammation by releasing or promoting healthy AM to release pro-inflammatory cytokines and chemokines, augmenting polymorphonuclear neutrophil (PMN) chemotaxis and suppressing T lymphocyte migration. receptor for advanced glycation end products high mobility group box 1 ( Moreover, we have also shown in our previous and preliminary studies that LPS and HMGB1 throughTLR4 upregulate TLR2 in AM, which in turn augments AM pyroptosis in response to bacteria-derived TLR2 ligands. Based on these findings, we hypothesize that: 1) AM pyroptosis may promote the development of ALI in sepsis by amplifying the inflammatory process; 2) HMGB1-RAGE signaling serves as a novel mechanism that induces AM pyroptosis in sepsis; and 3) TLR4 signaling-upregulated TLR2 serves as an important mechanism for augmented AM pyroptosis in sepsis. In order to test these hypotheses, we propose the following three specific aims:
Specific Aim #1 : to determine the role of AM pyroptosis in the development of ALI following sepsis.
Specific Aim #2 : to determine the molecular mechanism through which sepsis induces AM pyroptosis.
Specific Aim #3 : to determine the mechanism of TLR2 signaling-primed AM pyroptosis in sepsis.

Public Health Relevance

Acute lung injury (ALI) is a major component of multiple organ dysfunction syndrome (MODS) following sepsis; however, few specific targets have yet been identified that predispose to MODS and ALI in sepsis, rendering mortality rates high and effective treatment lacking. Gaining insight into the sepsis regulation of macrophage (M?death, particularly pyroptosis, and subsequent impact on the development of ALI will provide us with novel targets for preventive and therapeutic interventions for ALI in septic patients. Furthermore, in a broader sense, the proposed studies will contribute to a greater understanding of the pathogenesis of a number of human diseases in which M?s involved in the inflammatory process.

National Institute of Health (NIH)
Veterans Affairs (VA)
Non-HHS Research Projects (I01)
Project #
Application #
Study Section
Surgery (SURG)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Veterans Health Administration
United States
Zip Code
Chen, Linsong; Zhao, Yanfeng; Lai, Dengming et al. (2018) Neutrophil extracellular traps promote macrophage pyroptosis in sepsis. Cell Death Dis 9:597
Li, Zhi-Gang; Scott, Melanie J; Brzóska, Tomasz et al. (2018) Lung epithelial cell-derived IL-25 negatively regulates LPS-induced exosome release from macrophages. Mil Med Res 5:24
Jiao, Yang; Li, Zhigang; Loughran, Patricia A et al. (2018) Frontline Science: Macrophage-derived exosomes promote neutrophil necroptosis following hemorrhagic shock. J Leukoc Biol 103:175-183
Fan, Erica K Y; Fan, Jie (2018) Regulation of alveolar macrophage death in acute lung inflammation. Respir Res 19:50
Li, Zhigang; Jiao, Yang; Fan, Erica K et al. (2017) Aging-Impaired Filamentous Actin Polymerization Signaling Reduces Alveolar Macrophage Phagocytosis of Bacteria. J Immunol 199:3176-3186
Li, Zhigang; Fan, Erica K; Liu, Jinghua et al. (2017) Cold-inducible RNA-binding protein through TLR4 signaling induces mitochondrial DNA fragmentation and regulates macrophage cell death after trauma. Cell Death Dis 8:e2775
Xu, Fengying; Zhang, Chengmi; Zou, Zui et al. (2017) Aging-related Atg5 defect impairs neutrophil extracellular traps formation. Immunology 151:417-432
Lai, Deng-Ming; Shu, Qiang; Fan, Jie (2016) The origin and role of innate lymphoid cells in the lung. Mil Med Res 3:25
Yang, Weng-Lang; Sharma, Archna; Wang, Zhimin et al. (2016) Cold-inducible RNA-binding protein causes endothelial dysfunction via activation of Nlrp3 inflammasome. Sci Rep 6:26571
Yang, Jie; Zhao, Yanfeng; Zhang, Peng et al. (2016) Hemorrhagic shock primes for lung vascular endothelial cell pyroptosis: role in pulmonary inflammation following LPS. Cell Death Dis 7:e2363

Showing the most recent 10 out of 13 publications