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. 2022 Oct 1;58(4):287-294.
doi: 10.1097/SHK.0000000000001979. Epub 2022 Aug 18.

POSTINJURY FECAL MICROBIOME TRANSPLANT DECREASES LESION SIZE AND NEUROINFLAMMATION IN TRAUMATIC BRAIN INJURY

Booker T Davis 4th  1 , Zhangying Chen, Mecca B A R Islam  1 , Madeline E Timken  1 , Daniele Procissi, Steven J Schwulst  1
Affiliations

POSTINJURY FECAL MICROBIOME TRANSPLANT DECREASES LESION SIZE AND NEUROINFLAMMATION IN TRAUMATIC BRAIN INJURY

Booker T Davis 4th et al. Shock. .

Abstract

Background: Traumatic brain injury (TBI) is an underrecognized public health threat. The constitutive activation of microglia after TBI has been linked to long-term neurocognitive deficits and the progression of neurodegenerative disease. Evolving evidence indicates a critical role for the gut-brain axis in this process. Specifically, TBI has been shown to induce the depletion of commensal gut bacteria. The resulting gut dysbiosis is associated with neuroinflammation and disease. Hypothesis: We hypothesized that fecal microbiota transplantation would attenuate microglial activation and improve neuropathology after TBI. Methods: C57Bl/6 mice were subjected to severe TBI (n = 10) or sham injury (n = 10) via an open-head controlled cortical impact. The mice underwent fecal microbiota transplantation (FMT) or vehicle alone via oral gavage once weekly for 4 weeks after injury. At 59 days after TBI, mice underwent three-dimensional, contrast-enhanced magnetic resonance imaging. Following imaging, mice were killed, brains harvested at 60 DPI, and CD45+ cells isolated via florescence-activated cell sorting. cDNA libraries were prepared using the 10x Genomics Chromium Single Cell 3' Reagent kit followed by sequencing on a HiSeq4000 instrument, and computational analysis was performed. Results: Fecal microbiota transplantation resulted in a >marked reduction of ventriculomegaly (P < 0.002) and preservation of white matter connectivity at 59 days after TBI (P < 0.0001). In addition, microglia from FMT-treated mice significantly reduced inflammatory gene expression and enriched pathways involving the heat-shock response compared with mice treated with vehicle alone. Conclusions: We hypothesized that restoring gut microbial community structure via FMT would attenuate microglial activation and reduce neuropathology after TBI. Our data demonstrated significant preservation of cortical volume and white matter connectivity after an injury compared with mice treated with vehicle alone. This preservation of neuroanatomy after TBI was associated with a marked reduction in inflammatory gene expression within the microglia of FMT-treated mice. Microglia from FMT-treated mice enriched pathways in the heat-shock response, which is known to play a neuroprotective role in TBI and other neurodegenerative disease processes.

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Conflict of interest statement

The authors report no conflicts of interest.

Figures

Figure 1.
Figure 1.. FMT attenuates cortical volume loss and preserves white matter connectivity after TBI.
A) Representative MRI scans of animals (60DPI) with injury cerebrospinal fluid (CSF) ventricles are denoted in yellow for all groups: Sham (untreated, no injury), TBI (Untreated, with injury), FMT (Treated, No injury ((sham)), TBI-FMT (Treated, with injury). (N=3) B) Representative longitudinal and transverse images reveal the pattern of whole-brain fractional anisotropy. C) Mean head size of animals 60 days post-TBI reveals a significant effect of injury (p<0.0001) and the interaction between FMT and injury (p<0.04). D) Fluid diffusion highlights enlargement of ventricles with TBI. E) Fractional anisotropy (connectivity) data was extracted from MRI. FMT attenuates TBI-induced ventriculomegaly, a well-described surrogate for cortical volume loss (p<0.002). In addition, TBI induced a decrease in fractional anisotropy (white matter connectivity) compared to sham injury (p<0.0001). FMT treatment attenuated this loss of connectivity compared to vehicle-treated TBI mice (p=0.04).
Figure 2.
Figure 2.. FMT treatment prevents the expansion of the proportion of T cells after traumatic brain injury in mice.
Immune cells were isolated from mouse groups using Fluorescent Activated Cell Sorting and assessed via single-cell RNA sequencing for cell type. Immune cell proportions are shown here for all groups: Sham (untreated, no injury), TBI (Untreated, with injury), FMT (Treated, No injury ((sham)), TBI-FMT (Treated, with injury). A) UMAP plot demonstrating clustering obtained for each group (Sham, TBI, FMT, FMT-TBI) two biological replicates were combined. Cluster annotations: MG (microglia), T (T-cells) B (B-cells) NK (natural killer cells), NP (neutrophils), Mo_MΦ (monocytes/monocytes-derived macrophages), EC (epithelial cells). Number of total cells obtained from each group: Sham=3952, TBI=5570, FMT-Sham=3286, FMT-TBI=5832. B) Pie charts demonstrating the proportion of the identified cell types across samples. FMT mitigated the expansion in the proportion of T cells within the brain after TBI. C) Dim plots showing markers that identify each cell type. Average expression and percent expression are indicated by dot size.
Figure 3.
Figure 3.. FMT administration alters microglial gene expression after sham and brain injury
A) Microglia were grouped by gene expression according to function, revealing predominant microglia phenotypes within samples for all groups: Sham (untreated, no injury), TBI (Untreated, with injury), FMT (Treated, No injury ((sham)), TBI-FMT (Treated, with injury). The predominant phenotypes included microglia expressing 1. Homeostatic (HMG), 2. Disease-associated (DAM), 3. Inflammatory (INMG) and 4. Heat-shock (hspMG) related genes. B) Stacked bar charts demonstrating the proportion of DAM and hspMG microglia subclusters in injury and FMT, respectively. The microglia found within samples: FMT=2046, FMT_TBI=3435, Sham=2941, and TBI=3093.
Figure 4.
Figure 4.. Heatmap demonstrates a marked downregulation of inflammatory gene expression after FMT, further amplified after traumatic brain injury.
TBI results in a significant upregulation of inflammatory gene expression in microglia. Groups: Sham (untreated, no injury), TBI (Untreated, with injury), FMT (Treated, No injury ((sham)), TBI-FMT (Treated, with injury). Treatment with FMT markedly decreased inflammatory gene expression within the microglia of mice at baseline (sham-injury). This downregulation of inflammatory gene expression was further amplified after TBI.
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References

    1. Nittayasoot N, Peterson AB, Thammawijaya P, Parker EM, Sathawornwiwat A, Boonthanapat N, Chantian T, Voradetwitaya L, Jiraphongsa C, Sagarasaeranee O, et al.: Evaluation of a hospital-based injury surveillance system for monitoring road traffic deaths in Phuket, Thailand. Traffic Inj Prev 20(4):365–371, 2019. - PMC - PubMed
    1. Badhiwala JH, Wilson JR and Fehlings MG: Global burden of traumatic brain and spinal cord injury. Lancet Neurol 18(1):24–25, 2019. - PubMed
    1. DeKosky ST and Asken BM: Injury Cascades in TBI- Related Neurodegeneration. Brain Inj 31(9):1177–82, 2017. - PMC - PubMed
    1. Faul M and Coronado V: Chapter 1 - Epidemiology of traumatic brain injury. In Grafman J and Salazar AM (eds): Vol. 127. Elsevier, 2015, pp. 3–13. - PubMed
    1. Makinde HM, Cuda CM, Just TB, Perlman HR and Schwulst SJ: Nonclassical Monocytes Mediate Secondary Injury, Neurocognitive Outcome, and Neutrophil Infiltration after Traumatic Brain Injury. J Immunol 199(10):3583–3591, 2017. - PMC - PubMed

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