This proposal focuses on the physiologic condition of sepsis, which is the tenth leading cause of death in the US with a mortality rate of >215,000 patients a year. For this reason, numerous mono-centric clinical trials (i.e. one therapeutic) have been undertaken, but these trials have shown limited success. As such, a critical need still exists for new therapeutic approaches and treatments for sepsis. Elucidation of new molecular mechanisms controlling inflammation provides the necessary foundation upon which to build. In this regard, an early manifestation of sepsis is the development of an imbalance between pro- and anti-inflammatory lipids such as the arachidonic acid (AA)-derived eicosanoids and 3-polyunsaturated fatty acid (PUFA)-derived lipid mediators (e.g. eicosapentaenoic acid (EPA)-derived (e.g. E-resolvins) and docosahexaenoic acid (DHA)- derived (e.g. D-resolvins)). The synthesis of these lipid mediators begins with the initial rate-limiting step, the formation of AA, EPA, and DHA via the activity of a phospholipase A2 (PLA2). One of the major PLA2s involved in this initial step is group IVA cytosolic PLA2 (cPLA2? and the Chalfant laboratory demonstrated that the sphingolipid, ceramide-1-phosphate (C1P), directly binds and activates cPLA2? the cationic ? groove of the C2 domain. To evaluate the physiological relevance of this lipid:protein interaction, we created a knockin mouse with the endogenous C1P interaction site of cPLA2ablated (KI). Intriguingly, our preliminary data showed that KI mice, unlike the wild-type (WT) and cPLA2? knockout (KO) mice, exhibit complete resistance to sepsis including marked reduction in neutrophil infiltration into the peritoneum. Notably, these mice displayed lower levels of pro-inflammatory eicosanoids with concomitant increases in anti-inflammatory resolvins. This novel lipid profile, in contrast to WT and KO mice, correlates strongly with lipid profiles of human patients that recover from sepsis. Mechanistically, the KI mouse also demonstrated differential usage in the phospholipid precursors utilized for DHA and EPA generation suggesting a previously unknown/unsurmised modulating role for C1P in cPLA2? function/localization. Based on our preliminary findings, we hypothesize that the sepsis resistance of KI mice and associated differential synthesis of specific pro- and anti-inflammatory lipid mediators: i) will b reflected by a """"""""perfect storm"""""""" of lipid mediator production in human patients who recover from sepsis, which preserves endothelium function by suppressing neutrophil trans-endothelial migration;thereby limiting the hyper-inflammatory stage of sepsis;ii) will reflect a novel """"""""lipid class switch"""""""" in the use of phospholipid substrates involving differential localization of regulatory and lipid synthetic proteins;and iii) will show specific and direct interaction of the C1P headgroup and sphingoid with cPLA2? upon co-crystallization experiments, which will allow for the future rational design of new therapeutics. We will validate these hypotheses and inferences using a multi-disciplinary approach including cellular, biophysical, structural, biological, and pr-clinical experiments.
We are focusing on the physiologic condition of sepsis, which is a term used to describe a severe illness arising from serious infection. The mortality rate of sepsis is >215,000 patients a year, and unfortunately, clinical trials for treating sepsis have shown limited success. As such, there is a major need for new therapeutics, and our studies explore the cellular mechanisms and bioactive lipids involved in ameliorating this deadly condition.
|Katz, SebastiÃ¡n; Ernst, Orna; Avni, Dorit et al. (2016) Exogenous ceramide-1-phosphate (C1P) and phospho-ceramide analogue-1 (PCERA-1) regulate key macrophage activities via distinct receptors. Immunol Lett 169:73-81|
|Shapiro, Brian A; Vu, Ngoc T; Shultz, Michael D et al. (2016) Melanoma Differentiation-associated Gene 7/IL-24 Exerts Cytotoxic Effects by Altering the Alternative Splicing of Bcl-x Pre-mRNA via the SRC/PKCÎ´ Signaling Axis. J Biol Chem 291:21669-21681|
|Kolawole, Elizabeth Motunrayo; McLeod, Jamie Josephine Avila; Ndaw, Victor et al. (2016) Fluvastatin Suppresses Mast Cell and Basophil IgE Responses: Genotype-Dependent Effects. J Immunol 196:1461-70|
|Truchan, Hilary K; VieBrock, Lauren; Cockburn, Chelsea L et al. (2016) Anaplasma phagocytophilum Rab10-dependent parasitism of the trans-Golgi network is critical for completion of the infection cycle. Cell Microbiol 18:260-81|
|Vu, Ngoc T; Park, Margaret A; Shultz, Michael D et al. (2016) Caspase-9b Interacts Directly with cIAP1 to Drive Agonist-Independent Activation of NF-ÎºB and Lung Tumorigenesis. Cancer Res 76:2977-89|
|Stiles, Megan; Qi, Hui; Sun, Eleanor et al. (2016) Sphingolipid profile alters in retinal dystrophic P23H-1 rats and systemic FTY720 can delay retinal degeneration. J Lipid Res 57:818-31|
|Johnson, Ryan M; Vu, Ngoc T; Griffin, Brian P et al. (2015) The Alternative Splicing of Cytoplasmic Polyadenylation Element Binding Protein 2 Drives Anoikis Resistance and the Metastasis of Triple Negative Breast Cancer. J Biol Chem 290:25717-27|
|Ren, Aiming; Wang, Xin C; Kellenberger, Colleen A et al. (2015) Structural basis for molecular discrimination by a 3',3'-cGAMP sensing riboswitch. Cell Rep 11:1-12|
|Rao, Enyu; Singh, Puja; Zhai, Xiuhong et al. (2015) Inhibition of tumor growth by a newly-identified activator for epidermal fatty acid binding protein. Oncotarget 6:7815-27|
|Malinina, Lucy; Simanshu, Dhirendra K; Zhai, Xiuhong et al. (2015) Sphingolipid transfer proteins defined by the GLTP-fold. Q Rev Biophys 48:281-322|
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