Project description:Expression of 757 neuroinflammaiton-associated genes in vehicle and complement inhibitor treated TBI brains at days 3, 7 and 28 post injury
Project description:Traumatic brain injury (TBI) induces neuroinflammatory innate immune responses that plays roles in both worsening brain damage and facilitating functional recovery. A major goal is to understand the heterogeneity of the immune responses to TBI, and to precisely identify key components that impact functional outcomes. We previously demonstrated that genetically targeting Ccr2 in a mouse model of controlled cortical impact led to neuroprotection in TBI. Our current studies of TBI use single cell RNA sequencing of over 10,000 TBI ipsilateral brain leukocytes to examine the mechanisms associated with the observed benefit in Ccr2-/- mice by comparing gene expression in leukocyte subsets from Ccr2-/- mice to gene expression in C57BL/6 wild type mice. Unbiased clustering identified two monocyte subsets, Chil3hi Ly6Chi classical monocytes and Gpnmbhi Ly6Clo nonclassical monocytes, and nine microglia states in the ipsilateral TBI brain. Comparative analysis between the genotypes revealed that Ccr2-/- TBI mice contained reduced numbers of inflammatory macrophages. In TBI, we observed a subset of microglia highly expressing several type I interferon-stimulated genes (ISGs) and is designated as Irf7hi microglia. Notably, unbiased differential expression analysis detected a two-fold reduction in the type I interferon response in multiple Ccr2-/- TBI microglia subsets compared to wild type TBI microglia. Treatment post-injury with a human CCR2 (hCCR2) inhibitor, CCX872, in hCcr2 knock-in mice improved cognitive function post-TBI, and also correlated with reduced expression of a key ISG, Irf7. We identified and characterized macrophage and microglia subsets during acute TBI. Our data showed that a reduction in macrophage expansion in TBI by both genetic and pharmacological methods, improved TBI and correlated with a reduction in the type I IFN response. These data indicate that macrophage expansion co-directs a type IFN response in microglia, and that targeting macrophage expansion in the brain can alter the profile of microglia subsets and lead towards improved functional outcomes.
Project description:We inflicted TBI to chemokine-deficient mouse lines in order to establish involvement of various signalling pathways that may be addressed therapeutically. Interacting chemokine pathways in brain regulate distinct inflammatory cells. Activated microglia are separate from invading phagocytes and dendritic cells. Findings show potential targets to interfere with specific inflammatory responses after brain injury. TBI was carried out in Ccl3-/- and Ccr2-/- mice, total RNA prepared from injured cerebral neocortex after three days. RNA samples were from uninjured Ccl3-/- and Ccr2-/- mice as reference for hybridization on Affymetrix microarrays.
Project description:Post-traumatic neuroinflammation is a key driver of secondary injury after traumatic brain injury (TBI). Pyroptosis, a proinflammatory form of programmed cell death, considerably activates strong neuroinflammation and amplifies the inflammatory response by releasing inflammatory contents. Therefore, treatments targeting pyroptosis may beneficially effects for the treatment of secondary brain damage after TBI. Herein, a cysteine-alanine-glutamine-lysine (CAQK) peptide-modified β-lactoglobulin (β-LG) nanoparticle was constructed to deliver disulfiram (DSF), C-β-LG/DSF, to inhibit pyroptosis and decrease neuroinflammation, thereby preventing TBI-induced secondary injury. In the post-TBI mice model, C-β-LG/DSF selectively targets the injured brain, increases DSF accumulation, and extends the time of the systemic circulation of DSF. C-β-LG/DSF can alleviate brain edema and inflammatory response, inhibit secondary brain injury, promote learning, and improve memory recovery in mice after trauma. Therefore, this study likely provided a new approach for reducing the secondary spread of TBI.
Project description:The variations of psycho- and physiological deficits caused by TBI correlate with the degree of brain injury. However, the objective stratification of TBI is yet elusive. A modified closed-head injury Marmarou model was used based on the release of a 500 gram steel slug on top of the rat skull from a height of 100 cm or 120 cm to induce differential injury models for mild TBI and moderate TBI, respectively. The skull was covered by a helmet to mimic the warfighter’s condition in theater. The hippocampus was at the focal point of injury, and the cerebellum, was susceptible to diffused shock (secondary injury). The HC-CB axis coordinates visuomotor performance, which is known to be vulnerable to TBI. The rats that received moderate TBI showed deficient visuomotor performance by the Barnes maze test for longer time periods than those inflicted with mild TBI. The time resolved and HC-CB specific transcriptomic analysis focused on genes that enabled discrimination of mild from moderate TBI at 14d post injury which is equivalent to nearly 1.5 years of human lifetime. The functional analysis elucidated an active healing mechanism in the HC exposed to mild TBI. In contrast, moderate TBI caused delayed healing and active cell death in the HC. In conclusion, the graded brain injuries differentially implicated the HC-CB axis, despite the use of a helmet to reduce the impact. Time resolved functional dynamics informed the distinct consequences of mild vs. moderate TBI.