Severe sepsis, a clinical syndrome in patients with infection, surgery, trauma, or other injury, is associated with high mortality and limited effective therapeutics. High mobility group B1 (HMGB1), an endogenous molecule released by macrophages and other immunocompetent cells, is a necessary and sufficient mediator of lethal sepsis. Anti-HMGB1 antibodies that neutralize the cytokine activity of HMGB1 confer significant protection against inflammation, organ damage, and lethality in diverse animal models including severe sepsis, arthritis, pancreatitis, burn injury, acute lung injury, cerebral ischemia, hemorrhagic shock, colitis, and other inflammation and injury syndromes. The central tenet of the HMGB1 paradigm is that it mediates biological functions ranging from activating macrophages to secrete cytokines, to stimulating neutrophil migration. At present there are several major unanswered questions in this field, including: how do post-translational modifications alter HMGB1 interactions with TLR4 and RAGE, its two best understood and pre-eminent receptors? What is the effect of the HMGB1-TLR4 complex on activating intracellular signal transduction that drives cytokine release? Do HMGB1-TLR4 and HMGB1-RAGE complex formation mediate unique biological responses that can be dissociated in the context of sepsis? These questions will be addressed in the following Aims:
Specific Aim 1 : To elucidate whether cysteine modifications influence interaction of HMGB1-RAGE.
Specific Aim 2. To elucidate whether HMGB1-TLR4 activates TIRAP-MyD88 and TRAM-TRIF dependent signaling.
Specific Aim 3. To determine the beneficial effects of HMGB1- TLR4 or HMGB1-RAGE interaction in attenuating disease severity in sepsis. We propose to utilize an innovative strategy based on surface plasmon resonance to study HMGB1 binding to TLR4 and RAGE, substitution of specific amino acids to modify binding and signaling, proximity ligation assays to study intracellular binding of HMGB1 to TLR4 and RAGE, wholly synthetic peptides based on post- translational modified HMGB1 to produce competitive antagonists, and knockout mice to study these significant mechanisms in the context of lethal sepsis.
Severe sepsis is a major public health problem, because it is the leading cause of death in hospitalized patients in the United States, and one of the ten leading causes of death in the developed world. Recent evidence indicates that a protein, HMGB1, produced by the immune system, is a source of potentially lethal toxicity during sepsis. The studies proposed here will determine how HMGB1 activates the cells of the immune system to heighten the risk of death. This study will also analyze effects of HMGB1 antagonists to improve disease severity and survival in animal models of sepsis. This understanding will guide development of drugs to neutralize the toxicity of HMGB1 and prevent the complications of sepsis.
|Yang, Huan; Wang, Haichao; Levine, Yaakov A et al. (2016) Identification of CD163 as an antiinflammatory receptor for HMGB1-haptoglobin complexes. JCI Insight 1:|
|Li, Wei; Zhu, Shu; Li, Jianhua et al. (2015) Serum Amyloid A Stimulates PKR Expression and HMGB1 Release Possibly through TLR4/RAGE Receptors. Mol Med 21:515-25|
|Yang, Huan; Wang, Haichao; Ju, Zhongliang et al. (2015) MD-2 is required for disulfide HMGB1-dependent TLR4 signaling. J Exp Med 212:5-14|
|Ju, Zhongliang; Chavan, Sangeeta S; Antoine, Daniel J et al. (2014) Sequestering HMGB1 via DNA-conjugated beads ameliorates murine colitis. PLoS One 9:e103992|
|Lu, Ben; Antoine, Daniel J; Kwan, Kevin et al. (2014) JAK/STAT1 signaling promotes HMGB1 hyperacetylation and nuclear translocation. Proc Natl Acad Sci U S A 111:3068-73|
|GerÃ¶, Domokos; Szoleczky, Petra; MÃ³dis, Katalin et al. (2013) Identification of pharmacological modulators of HMGB1-induced inflammatory response by cell-based screening. PLoS One 8:e65994|
|Yang, Huan; Antoine, Daniel J; Andersson, Ulf et al. (2013) The many faces of HMGB1: molecular structure-functional activity in inflammation, apoptosis, and chemotaxis. J Leukoc Biol 93:865-73|
|Patel, Vivek S; Sitapara, Ravikumar A; Gore, Ashwini et al. (2013) High Mobility Group Box-1 mediates hyperoxia-induced impairment of Pseudomonas aeruginosa clearance and inflammatory lung injury in mice. Am J Respir Cell Mol Biol 48:280-7|
|ValdÃ©s-Ferrer, S I; Rosas-Ballina, M; Olofsson, P S et al. (2013) HMGB1 mediates splenomegaly and expansion of splenic CD11b+ Ly-6C(high) inflammatory monocytes in murine sepsis survivors. J Intern Med 274:381-90|
|ValdÃ©s-Ferrer, Sergio I; Rosas-Ballina, Mauricio; Olofsson, Peder S et al. (2013) High-mobility group box 1 mediates persistent splenocyte priming in sepsis survivors: evidence from a murine model. Shock 40:492-5|
Showing the most recent 10 out of 44 publications