Lipidomics

Lipidomics

1. Lipids = fatty acids and their derivatives

   • and substances related to biosynthetically or functionally to these compounds
   • 8 classes and each have subclasses
   • 3 main functions of lipids
     • structural and functional components of all membrane and membrane proteins
     • Energy homeostasis
     • intra- and inter-cellular signalling

2. Lipidome = complete lipid profile of an organism

3. Lipidomics = large-scale study of pathways and networks of cellular lipids in biological systems

   • enabled largely by MS and MS technologies
     • MS can be targeted or non targeted
       • targeted = use of identification / quantification of predicted subset of lipids
       • non targeted = aim to provide an unbiased 'snapshot' of all / many of lipids in the sample

4. Can play role in biomarker search

   • nutritional biomarker =
     • objectively measured in different biological samples and used as indicator of nutritional status
   • 3 ways
     • hep monitor dietary exposure
     • to study relationships between food intake and health parameters
     • Provide insights into metabolic pathways by which target food may exert its health effect
   • Nutritional biomarker search - 3 approaches
     • acute intervention
     • cohort studies
     • analysis of dietary patterns and metabolic profiles

5. PUFA derived lipid mediators

   • oxylipins derived from oxygenation of omega 6 and omega 3 PUFAs
   • Generated via enzymatic pathways or free radical mediated mechanisms
   • Eicosanoids and docasonoids
     • key regulators of acute and chronic inflammation
       • proinflammatory - prostaglandins
       • pro-resolving - resolvins

6. Challenges

   • Present at very low concentrations
   • transient - quick formation and degradtion
   • many isomettric species
   • unstable at room temp
   • platelets can be activated - postglandulins
   • lack of internal standard
   • need very sensitive analytical techniques

7. Controversies

   • do these mediators circulate in blood
   • does plasma levels reflect in vivo biosynthesis