Laboratory for Metabolomics



1. Development and application of target and non-target multi-lipidomics platform


   LC-MS/MS-based lipidomics concerns the simultaneous and quantitative analysis to find a potential link between lipid metabolism and biological phenotype. A triple quadrupole (TripleQ) mass spectrometer is capable of carrying out an target MS method called multiple reaction monitoring (MRM). A specified precursor ion is selected according to its mass-to-charge ratio (m/z) in the first quadrupole mass filter, and is fragmented into product ions in the second chamber, then the third quadrupole mass filter is locked on its specified product ion. We developed a comprehensive MRM method that can simultaneously detect and quantify more than 500 of diverse fatty acid metabolites. A quadrupole Time-of Flight (Q-TOF) mass spectrometer provides the ability to perform non-target analyses with high resolution and accurate MS/MS informations. MS/MS trigger is set at low threshold level in order to detect as globally as possible, and lipid structures are unbiasedly identified by in-house lipid database screening. 




Fig.1   Non-target multi-lipidomics platform to discover potential link between lipid metabolism and biological phenotypes

  Non-target multi-lipidomics platform enables us to discover potential link between lipid metabolism and biological phenotypes. By taking advantage of Q-TOF (global lipid screening) and TripleQ (quantitative analyses) mass spectrometers, our new approach has a strong potential to search for lipids of interest globally, or to identify unknown lipid species in non-biased fashion.

  Also, all software programs and lipid database are freely available at RIKEN PRIMe and Lipoquality DB websites, respectively.

2. Genetic and lipidomic approach to understand anti-inflammatory property of omega-3 PUFAs

    Dietary fatty acid balance is recognized as an important factor in immune regulation and disease controls. Especially omega-3 polyunsaturated fatty acid (PUFA) including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are widely held to be beneficial in many inflammatory disorders including cardiovascular disease, arthritis, colitis, and metabolic syndrome. Also, elevation in omega-3 PUFA levels in omega-3 desaturase (fat-1) transgenic mice that endogenously biosynthesize omega-3 PUFA from omega-6 PUFA exhibits resistance to inflammatory disease models. To elucidate the molecular mechanisms underlying the beneficial effects of omega-3 PUFAs, we developed a comprehensive LC-MS/MS-based lipidomics method that can detect and quantify more than 500 of fatty acid metabolites simultaneously. Using a genetic model, namely fat-1 transgenic mice, we examine the impact of enhanced omega-3/omega-6 ratio in inflammation and tissue homeostasis. Also we demonstrate LC-MS/MS-based lipidomic analyses, and identified potent anti-inflammatory metabolites and key metabolic pathways for omega-3 PUFAs. These metabolites may underlie some of the beneficial actions of omega-3 PUFAs in controlling inflammation and related diseases.


3. Mediator lipidomics in acute inflammation and resolution

   Acute inflammation is an indispensable host response to foreign challenges or tissue injury. In healthy conditions, inflammatory processes are self-limiting and self-resolving, suggesting the existence of endogenous mechanisms for the control of inflammation and resolution. A comprehensive understanding of the cellular and molecular events of a well-orchestrated inflammatory response is required, and recent studies have uncovered the roles of endogenous lipid mediators derived from polyunsaturated fatty acids in controlling the resolution of inflammation.




We applied LC-MS/MS-based mediator lipidomics to the self-resolving acute peritonitis model, and provided new insights into the cellular and molecular mechanisms of inflammatory resolution, especially the functional roles of 12/15-lipoxygenase(12/15-LOX)-expressing eosinophils and macrophages in controlling the resolution of inflammation.  


4. Lipidomics in health and disease

    Mediator lipidomics concerns the simultaneous and quantitative analysis of bioactive lipid mediators in biological systems. When combined with proteomic, transcriptomic, and genomic profiles (multi-omics profiling), it can greatly assist in understanding the role of lipid mediators in certain biological and/or pathological conditions. This technology could potentially identify the metabolic fingerprint of a disease for clinical diagnosis and treatment. Indeed, we revealed impaired 12/15-LOX activity in eosinophils isolated from severe asthmatics patients as compared to the healthy subjects. Also 12/15-LOX-deficient mice were more susceptible to illness of influenza virus infection. These results indicate the potential link and protective role of endogenous lipid mediators biosynthesized via the 12/15-LOX-mediated pathway. Moreover, endogenous lipid mediators with anti-inflammatory and tissue-protective actions could lead to the development of novel therapeutics for human disease when sustained inflammation is suspected as key components of pathogenesis.




July 2014:  Genetic and lipidomic approach uncovers cardioprotective mechanism by omega-3 fatty acid