Ultrahigh Resolution Mass Spectrometry Imaging Maps Brain Lipidome Alterations Associated with Mild Traumatic Brain Injury.

Background:Traumatic brain injury (TBI) is a global public health problem, with 50-60 million incidents per year, most of which are considered mild (mTBI). Despite its massive impact, the pathology of TBI is not fully understood, and there is a paucity of information on brain lipid dysregulation following mTBI. To gain more insight on mTBI pathology, a non-targeted spatial metabolomics workflow utilizing ultrahigh resolution mass spectrometry imaging was developed to measure brain region-specific lipid alterations in rats. Results:Multivariate models were created for regions of interest including the hippocampus, cortex, corpus callosum, white matter and gray matter to identify lipids that discriminated between control and injured brains. The hippocampus model differentiated control and injured brains with an area under the curve of 0.994, using only four lipid markers. Lipid classes that were consistently selected for discrimination included polyunsaturated fatty acid-containing phosphatidylcholines (PC), lysophosphatidylcholines (LPC), LPC-plasmalogens (LPC-P), PC potassium adducts and ceramide phosphoinositols (PI-Cer). Many of the polyunsaturated fatty acid-containing PC, LPC-P, and PI-Cer selected have never been previously reported as altered in TBI. Significance:The lipid alterations observed indicate that neuroinflammation, oxidative stress and disrupted sodium-potassium pumps are important pathologies that can explain cognitive deficits associated with mTBI. Therapeutics which target and attenuate these pathologies may be beneficial to limit persistent damage following a mild brain injury.