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Temporal changes in the microglial proteome of male and female mice after a diffuse brain injury using label-free quantitative proteomics

ABSTRACT: Traumatic brain injury (TBI) triggers neuroinflammatory cascades mediated by microglia, which promotes tissue repair in the short-term. These cascades may exacerbate TBI-induced tissue damage and symptoms in the months to years post-injury. However, the progression of the microglial function across time post-injury and whether this differs between biological sexes is not well understood. In this study, we examined the microglial proteome in the days (3- and 7-days) to 1 month (28 days) after a midline fluid percussion injury (mFPI) in male and female mice using label-free quantitative proteomics. We identified a reduction in microglial proteins involved with clearance of neuronal debris via phagocytosis at 3- and 7-days post-injury. At 28 days post-injury pro-inflammatory proteins were decreased and anti-inflammatory proteins were increased in microglia. These results indicate a reduction in microglial clearance of neuronal debris in the days post-injury with a shift to anti-inflammatory function by 1 month. The changes in the microglial proteome that occurred across time post-injury did not differ between biological sexes. However, we did identify an increase in microglial proteins related to pro-inflammation as well as insulin and estrogen signalling in males compared with female mice that occurred with or without a brain injury. Although microglial response was similar between males and females up to 1 month following TBI, biological sex differences in the basal microglial proteome has implications for the efficacy of treatment strategies targeting the microglial response post-injury.

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ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Microglia

SUBMITTER: Richard Wilson

LAB HEAD: Dr Richard Wilson

PROVIDER: PXD033628 | Pride | 2023-03-11

REPOSITORIES: Pride

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Temporal changes in the microglial proteome of male and female mice after a diffuse brain injury using label-free quantitative proteomics.

Doust Yasmine V YV Bindoff Aidan A Holloway Olivia G OG Wilson Richard R King Anna E AE Ziebell Jenna M JM

Glia 20221205 4

Traumatic brain injury (TBI) triggers neuroinflammatory cascades mediated by microglia, which promotes tissue repair in the short-term. These cascades may exacerbate TBI-induced tissue damage and symptoms in the months to years post-injury. However, the progression of the microglial function across time post-injury and whether this differs between biological sexes is not well understood. In this study, we examined the microglial proteome at 3-, 7-, or 28-days after a midline fluid percussion inj ...[more]

PMID: 36468604

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Project description:Traumatic brain injury (TBI) is a leading cause of death and disability globally. Several studies have shown that 5-lipoxygenase (5-LOX) inhibition reduces leukotriene (LT) release and the inflammatory response, attenuating the development of respiratory diseases, myocardial infarction, and ischemic cerebral injury. However, its role in the pathophysiology of TBI remains unclear. In this study, controlled cortical impact injury was induced to construct a mouse model of TBI. Pericontusional brain tissue samples from sham and TBI mice at 7 days after injury were used for RNA-seq analysis. Altered gene enrichment following TBI, based on Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, was quantified through real-time polymerase chain reaction (RT-PCR). Immunocytochemistry, Western blotting, and single-cell sequencing experiments were also performed to analyze 5-LOX protein expression. Arachidonic acid (AA) was detected through liquid chromatography mass spectrometry/mass spectrometry. Enzyme-linked immunosorbent assay was used to detect LTB4 release after TBI with or without zileuton treatment. Brain damage, blood–brain barrier disruption, and neuronal apoptosis were detected through histological examination. Neurological outcomes were determined through rotarod and fear conditioning tests. TBI induced significant upregulation of genes related to the AA metabolic pathway, particularly the AA/5-LOX/LT axis, as verified by RT-PCR. AA and LTB4 production increased significantly after TBI. The expression levels of Pla2g4a, which hydrolyses phospholipids to release AA, and 5-LOX, which in turn act downstream to convert AA to LT, were dramatically upregulated up to 7 days after TBI. 5-LOX accumulated in the cytoplasm of activated ameboid microglial cells. In vivo, 5-LOX inhibition with zileuton blocked LT release and reduced microglial activation and the production of inflammatory cytokines, including Il-1β, Ccl7, Spp1, Ccr1, Ccl2, and Il-10. Zileuton also reduced TBI-induced lipid ROS and neuronal cell apoptosis, ameliorating brain damage compared to the vehicle group and improving neurological outcomes after TBI. Mechanically, TBI-induced LT upregulation may stimulate BV2 microglial activation through the ERK, NF-κB, and Akt pathways. Our findings demonstrated the role of 5-LOX in TBI and its potential as a therapeutic target in TBI treatment.

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