Week 5 part 2 Flashcards
Define Lipidomics
Subset of metabolomics, which focus on the study lipidome (complete collection of lipids in a cell, an organ, or a biological system)
What does research in lipidomics involve?
- precise identification of structures of cellular lipid species, including the number of atoms, the number and location of double bonds, core structures and head groups, individual fatty acid chains)
- Determine the interaction of individual lipid species with other lipids, proteins and metabolites in vivo
- Accurately quantifying individual lipid species for pathway analysis
- disclosing the nutritional or therapeutics status for prevention or therapeutic intervention
What is the Lipids Maps Structure Database (LMSD) i?
Relational database encompassing structures and annotations of biologically relevant lipids
From 02/04/2019, What does the LMSD contain?
43308 unique lipid structures
What are the 8 classes of lipids?
- Fatty Acyls [FA] (e.g. eicosanoids)
- Glycerolipids [GL] (e.g. Triglycerides)
- Glycerophospholipids [GP] (e.g. phosphatidylserine]
- Sphingolipids [SP] (e.g. Ceramides]
- Sterol Lipids [ST] (e.g. steroids)
- Prenol Lipids [PR] (e.g. Quinones)
- Saccharolipids [SL] (e.g. Acylaminosugars)
- Polyketides [PK] (e.g. Flavonoids)
What is the key technology for lipid species?
mass spectrometry
Why do Lipidologist possess a ‘‘biological intelligence’’?
allows them to interpret MS data in a manner that recognises what is likely or not likely to be the correct structure of a particular lipid species
What are the requirements for lipids?
lipids should be defined by both their class and their nominal mass (Da)
What are the various structural combinations of Lipid nomenclature?
- location of double bonds or attachment groups
- Attachment groups
- Head group
- Backbone
What are two lipids involved in energy storage?
diglyceride and triglyceride
What is the function of fat/triglyceride?
- energy store formed via fatty acid synthesis predominantly in liver
- stored mainly as fat in adipose tissues
What do cells with mitochondria have?
Lipoproteins
What are the two cell types that doesn’t use triglyceride directly for energy?
- Red blood cells due to absent mitochondria
2. cells in brain due to triglyceride not being able to cross blood brain barrie
What is used for energy during non-fed state?
- Ketoacids made from fat in liver
What lipids are insoluble in water and must be transported in association with proteins in the circulation?
- Cholesterol
2. Triglyceride
What is transported as triglyceride to avoid toxicity?
- large quantities of fatty acids from meals
What are lipoproteins?
complex particles that have a central hydrophobic core of non-polar lipids
e.g. cholesterol esters and triglyceride
What are plasma lipoproteins
7 classes based on:
- size
- lipid composition
- Apolipoproteins
What can Lipoproteins exist in?
5 major forms
What does 5 major forms of Lipoproteins contain?
- Triglycerides
- Phospholipids
- Cholesterol
- Proteins
What are the 5 major forms of Lipoprotein?
- Chlyomicrons
- VLDL
- Intermediate density lipoprotein (IDL)
- LDL
- HDL
What are Chylomicron?
Exogenous lipids are packaged by endoplasmic reticulum in small intestine epithelial cells then transported to blood
metabolised by muscle and adipose tissue by lipoprotein lipase
ULDL remnants are taken up by liver and enter endogenous lipoprotein pathway
What are VLDL
Endogenous triglyceride are packaged in hepatocytes and transported to muscle for energy or adipocytes for storage via circulation
What are IDL?
partially metabolised VLDL
What are LDL?
Metabolised product from IDL and transport cholesterol to liver
More susceptible to oxidation, which could result in an enhanced uptake by macrophages
What are HDL?
Transport of cholesterol to steroidogenic organs ( e.g. adrenals, ovary, testes) or to live for excretion in bile
Have anti-oxidant, anti-inflammatory, anti-thrombotic and anti-apoptotic properties
Enriched in cholesterol and phospholipid
Where are chylomicrons made by?
Intestine
involved in transport of dietary triglyceride to periperhal tissues and liver
What does a high fat meal lead to?
Formation of large chylomicron due to the increased amount of triglyceride being transported
What results in the formation of IDL particles which are enriched in cholesterol?
The removal of triglyceride from VLDL by muscle and adipose tissue
What are LDL partciles susceptible to?
- Oxidation
result in an enhanced uptake of macrophages
What does HDL play an important role in?
Reverse cholesterol transport from peripheral tissues to the liver
What are the characteristics of HDL particles?
- anti-oxidant
- Anti-inflammatory
- Anti-thrombotic
- Anti-apoptotic
- Inhibit atherosclerosis
What are HDL particles enriched in?
- Cholesterol
2. Phospholipids
What are examples of Glycerolipids (GL)?
- Diglycerol (DG; main component of cell membrane)
2. Phosphatidylethanolamine (PE; second most abundant component of cell membrane)
What are Glycerophospholipids?
- Phosphatidylcholine (PC; main component of cell membrane)
- Phosphatidylethanolamine (PE; second most abundant component of cell membrane)
- Triglyceride (TG; important in the formation of lipid bi-layer of cell membrane)
What are sterol lipids (ST)?
- Cholesterol (Chol; important in structural integrity and fluidity of cell membrane)
What are Sphingolipids (SP)?
- Ceramide (Cer; important components of sphingomyelin and cerebroside present in cell membrane)
- Sphingomyelin (SM; located especially in cell membrane of myelin sheath)
What are Fatty acids (FA)?
- Prostaglandin E2 (important in pro-inflammation, pain perception)
- Thromboxane A2 (important in blood platelet aggregation)
- Docosahexanoic acid (DHA; important in anti-inflammation and gene expression)
What are Glycerolipids (GL)?
- Diglycerol (DG; key signalling molecule as able to diffuse in and out of cell membrane)
able to activate protein kinase C and NFKB to encourage cell survival
What are Sphingolipids (SP)?
- Ceramide (Cer; key regulators of signal transduction processes essential for normal development, important in anti-inflammation, cell proliferation, apoptosis and cell survival
- Sphingomyelin (SM; important in apoptosis and cell survival)
What are the techniques to study Lipidomics?
- Mass spectrometry (MS)
- Nuclear magnetic resonance (NMR)
- High-performance liquid chromatography (HPLC)
- Microfluid devices
What does microfluids deal with?
- very precise fluid control, under small volumes and spaces,
- small volumes
- small size
- Low energy consumption
- Allow complete laboratory protocols on a single chip of few square centrimetres
What are the applications that microfluidic can be applied to?
- Cosmetic (emulsions and formulation)
- Pharmaceutical (Drug discovery)
- Health (personalised medicine and diagnosis)
- Chemostry (flow synthesis and stoichiometry)
- Biology (cell culture and 3D printing)
- Energy (EOR models plasma confinment)
What is Schizophrenia?
A disease when individuals have severely disrupted beliefs and experiences
What are the characteristrics of schizophrenia?
- Loss touch with reality
- See or hear things that are not there
- Hold irrational or unfounded beliefs
- Delusions and hallucinations
What are the several hypotheses that cause schizophrenia?
- Altered neurotransmission
- Autoimmune dysfunction
- Dysregulation of inflammation
- Changes to membrane phospholipid composition
What are the phospholipid hypothesis?
- Deficient uptake or excessive breakdown of membrane phospholipids or changes in phospholipid composition
- Lipid abnormalities observed in post-mortem grey and white matter samples with schizophrenia
- Lipid abnormalities observed in blood samples of patients with schizophrenia
- Increased phospholipase A2 activity in first onset patients with schizophrenia and associated with strucutal brian changes
How are prostaglandin synthesised?
- hydrolysis of phosphatidyl coline (PC) by action of phospholipase A2
What has global studies of lipid enable?
Comprehensive and sensitive measurement of molecular lipid
including phospholipid in biofluids and tissues
Lipid biomarker in Schizophrenia - methods
- Study protocol was reviewed and approved by the institution review board
- All participants provided informed consent
- Same sex twin pairs discordant for schizophrenia were identified in Finland
- ~83% heritability and 17~ environmental
- Healthy Finnish twin pairs with age and gender match acted as control
- Blood sampling from confirmed diagnosis of Schizophrenia that are not inpatients at time of study
How was symptom severity quantified?
- Scale for Assessment of Negative Symptoms (SANS)
2. Scale for Assessment of Positive symptoms (SAPS)
What did all participants take part in?
Extensive neurocognoitive assessment with established tasks known to be sensitive to cognitive deficits in schizophrenia
What was the methods for the study?
- EDTA blood samples (10ml) were collected and centrifuged within 2h of collection
- Top liquid phase was collected and stoed at -80c
- 10 microlitre of plasma was mixed with sodium chloride and spiked with a standard mixture of 10 lipids
- Lipids in serum mixture was extracted with 100microlitre chloroform/methanol
- After vortexing, standing at RTP, centrifugatiom lower organic phase was collected and spiked with 3 labelled lipods
- Lipid extract analysed randomly using UPLC, then LC-MS
What was Data analysis?
- Data was normalized using one or more internal standard representative of each class of lipids present
How was lipid intensity normalized?
Dividing with corresponding standard lipid and multiplying by concentration of standard
How was individual lipid metabolite levels visualised?
- beanplot algorithm implemented in R
What does beanplot provide?
- data point
- mean metabolite level within each group
- density of data-point distribution
What is used to group lipids into clusters?
- Bayesian model-based clustering
2. use MCLUST for analysis and R to implement
What was the results?
- Global lipidome profiling detected 530 molecular lipids, but only 250 were identified
- Bayesian model-based clustering created 7 clusters, termed LC1-7, which differ in lipid functional and structural groups
What was diminished in Schizophrenia patients compared to co-twins?
LysoPCs
What was elevated in patients compared to their co-twins?
TGs from LC5
What was the greatest change, but mo significance overall?
LC4 + 5
What was decreased in LC4?
Lysophosphosphatidylcholine (LysoPCs)
What was increased in LC5?
Triglyceride
What was the largest cluster but no change observed?
LC2 group
What was inceased in patients vs their healthy co-twins?
Sphingomyelin
What does increase in triglyceride in serum indicate/?
enhanced hepatic very low density lipoprotein (VLDL) production
What is decrease in lysopCs associated with?
Decreased cognition
What is lysoPC?
Main carrier of polyunsaturated fatty acid (pUFAs) across blood brain barrier into brain
What is PUFAs important for?
Normal brain development and function
What is prolong low lysopC level associated with?
increased susceptibility to infection
What has infection been suggested to play a role in?
Development of schizophrenia
What is found in cell membrane, especially myelin sheath?
Sphingomyelin
What does increase in serum suggest?
There is a breakdown of myelin or death of oligodendrocytes in schizophrenic patients
What may be due to side effects of antipsychotic drugs?
metabolic abnormality
What is a major demographic trend worldwide due to improved health and longevity?
Population ageing
What is Ageing?
complex process since several alterations of biochemical proccesses occur throughout our life
What has Ageing been suggested as?
low grade systemic inflammation termed ‘inflammagin’
What contributes to onset and progression of age-related disease, fraility and death?>
Inflammaging
Lipidomics biomarker in ageing- intro
The human plasma lipidome composed of thousand of different lipids
What has total triglyceride, HDL and LDL particle size been associated with?
Human familial longevity and healthy aging
What has been suggested as a marker of longevity and healthy aging?
A higher ratio of monounsaturated fatty acids over polyunsaturated fatty acids
What are the possible reasons for differences in sexes ?
- Body fat
- Hormonal regulation of lipid metabolism
- Menopause
