Temporal proteomics of human cerebrospinal fluid after severe traumatic brain injury

Abstract

The pathophysiology of traumatic brain injury (TBI) requires further characterization to fully elucidate changes in molecular pathways. Cerebrospinal fluid (CSF) provides a rich repository of brain-associated proteins. In this retrospective observational study, we implemented high-resolution mass spectrometry to evaluate changes to the CSF proteome after severe TBI. 91 CSF samples were analyzed with mass spectrometry, collected from 16 patients with severe TBI (mean 32 yrs; 81% male) on day 0, 1, 2, 4, 7 and/or 10 post-injury (8–16 samples/timepoint) and compared to CSF obtained from 11 non-injured controls. We quantified 1152 proteins with mass spectrometry, of which approximately 80% were associated with CSF. 1083 proteins were differentially regulated after TBI compared to control samples. The most highly-upregulated proteins at each timepoint included neutrophil elastase, myeloperoxidase, cathepsin G, matrix metalloproteinase-8, and S100 calcium-binding proteins A8, A9 and A12—all proteins involved in neutrophil activation, recruitment, and degranulation. Pathway enrichment analysis confirmed the robust upregulation of proteins associated with innate immune responses. Conversely, downregulated pathways included those involved in nervous system development, and several proteins not previously identified after TBI such as testican-1 and latrophilin-1. We also identified 7 proteins (GM2A, Calsyntenin 1, FAT2, GANAB, Lumican, NPTX1, SFRP2) positively associated with an unfavorable outcome at 6 months post-injury. Together, these findings highlight the robust innate immune response that occurs after severe TBI, supporting future studies to target neutrophil-related processes. In addition, the novel proteins we identified to be differentially regulated by severe TBI warrant further investigation as potential biomarkers of brain damage or therapeutic targets.

A metabolomic and proteomic analysis of pathologic hypercoagulability in traumatic brain injury patients after dura violation

“…Our data describe significant changes in several proteins related to platelet activation and activation with positive correlations to measurements of clot strength, including apolipoproteins, which are also known to be involved in the neuroinflammatory response to brain injury 13 . Other proteomic work describes significantly increased levels of proteins related to neutrophil degranulation and mobilization, which in sum with our work highlight a picture of pan-cellular hyperactivity and recruitment 49 . The proteomic data additionally showed key increases in antiplasmin and fibrinogen, which correlated to hypercoagulability on thrombelastography.…”

“…Examining the mechanisms and natural history of TBI has been recently empowered by proteomic data, which has further characterized the neuroinflammatory response to TBI. 49 Our data describe significant changes in several proteins related to platelet activation and activation with positive correlations to measurements of clot strength, including apolipoproteins, which are also known to be involved in the neuroinflammatory response to brain injury. 13 Other proteomic work describes significantly increased levels of proteins related to neutrophil degranulation and mobilization, which in sum with our work highlight a picture of pan-cellular hyperactivity and recruitment.…”

“…To complement the metabolomic data which characterizes a shift toward platelet hyperactivity and fibrinolysis shutdown, our proteomic data demonstrated key increases in proteins related to platelet activation, degranulation, and aggregation which correlated to thrombelastographic measurements of platelet activity. Examining the mechanisms and natural history of TBI has been recently empowered by proteomic data, which has further characterized the neuroinflammatory response to TBI 49 . Our data describe significant changes in several proteins related to platelet activation and activation with positive correlations to measurements of clot strength, including apolipoproteins, which are also known to be involved in the neuroinflammatory response to brain injury 13 .…”

“…13 Other proteomic work describes significantly increased levels of proteins related to neutrophil degranulation and mobilization, which in sum with our work highlight a picture of pan-cellular hyperactivity and recruitment. 49 The proteomic data additionally showed key increases in antiplasmin and fibrinogen, which correlated to hypercoagulability on thrombelastography. Fibrinogen is known to increase immediately after TBI before a precipitous decline and is believed to participate in destruction of the blood-brain barrier and neuroinflammation.…”

Research progress in the application of proteomics technology in brain injury

“…This provides proteomic clues for the different pathogenesis of sTBI in the acute and subacute phases and also provides potential signaling pathways and targets for future research. To further investigate the pathological mechanisms involved after TBI, Shultz et al (2022) compared the CSFs obtained from sTBI patients with those from the control group. In total, 1152 proteins were identified, of which approximately 80% were associated with CSF.…”