Microglia activation mediated by toll-like receptor-4 impairs brain white matter tracts in rats

Abstract

Microglia activation and white matter injury coexist after repeated episodes of mild brain trauma and ischemic stroke. Axon degeneration and demyelination can activate microglia; however, it is unclear whether early microglia activation can impair the function of white matter tracts and lead to injury. Rat corpus callosum (CC) slices were treated with lipopolysaccharide (LPS) or LPS + Rhodobacter sphaeroides (RS)-LPS that is a toll-like receptor 4 (TLR-4) antagonist. Functional changes reflected by the change of axon compound action potentials (CAPs) and the accumulation of β-amyloid precursor protein (β-APP) in CC nerve fibers. Microglia activation was monitored by ionized calcium binding adaptor-1 immunofluorescent stain, based on well-established morphological criteria and paralleled proportional area measurement. Input-output (I/O) curves of CAPs in response to increased stimuli were significantly downshifted in a dose-dependent manner in LPS (0.2, 0.5 and 1.0 µg/mL)-treated slices, implying that axons neurophysiological function was undermined. LPS caused significant β-APP accumulation in CC tissues, reflecting the deterioration of fast axon transport. LPS-induced I/O curve downshift and β-APP accumulation were significantly reversed by the pre-treatment or co-incubation with RS-LPS. RS-LPS alone did not change the I/O curve. The degree of malfunction was correlated with microglia activation, as was shown by the measurements of proportional areas. Function of CC nerve fibers was evidently impaired by microglia activation and reversed by a TLP-4 antagonist, suggesting that the TLP-4 pathway lead to microglia activation.

Keywords

lipopolysaccharide / Rhodobacter sphaeroides / toll-like receptor 4 / microglia activation / white matter tract malfunction

References

[1] Bao HX, Chen Z, Lu XL, Effects of rush entry into plateau on recruits' cognitive function[J]. J Third Mil Med Univ, 2013, 35: 1498–1500.

[2] Fu HQ, Yang T, Xiao W, Prolonged neuroinflammation after lipopolysaccharide exposure in aged rats[J]. PLoS One, 2014, 9(8): e106331

[3] Belanger HG, Vanderploeg RD, Sayer N. Screening for remote history of mild traumatic brain injury in VHA: A critical literature review[J]. J Head Trauma Rehabil, 2016, 31(3): 204–214

[4] Talavage TM, Nauman EA, Breedlove EL, Functionally-detected cognitive impairment in high school football players without clinically-diagnosed concussion[J]. J Neurotrauma, 2014, 31(4): 327–338

[5] Galgano MA, Cantu R, Chin LS. Chronic traumatic encephalopathy: the impact on athletes[J]. Cureus, 2016, 8(3): e532

[6] Winston CN, Noël A, Neustadtl A, Dendritic spine loss and chronic white matter inflammation in a mouse model of highly repetitive head trauma[J]. Am J Pathol, 2016, 186(3): 552–567

[7] Perez-Polo JR, Rea HC, Johnson KM, A rodent model of mild traumatic brain blast injury[J]. J Neurosci Res, 2015, 93(4): 549–561

[8] Smith C, Gentleman SM, Leclercq PD, The neuroinflammatory response in humans after traumatic brain injury[J]. Neuropathol Appl Neurobiol, 2013, 39(6): 654–666

[9] Suenaga J, Hu X, Pu H, White matter injury and microglia/macrophage polarization are strongly linked with age-related long-term deficits in neurological function after stroke[J]. Exp Neurol, 2015, 272: 109–119

[10] Psilodimitrakopoulos S, Petegnief V, de Vera N, Quantitative imaging of microtubule alteration as an early marker of axonal degeneration after ischemia in neurons[J]. Biophys J, 2013, 104(5): 968–975

[11] Furukawa S, Sameshima H, Yang L, Regional differences of microglial accumulation within 72 hours of hypoxia-ischemia and the effect of acetylcholine receptor agonist on brain damage and microglial activation in newborn rats[J]. Brain Res, 2014, 1562: 52–58

[12] Sponheim SR, McGuire KA, Kang SS, Evidence of disrupted functional connectivity in the brain after combat-related blast injury[J]. Neuroimage, 2011, 54(Suppl 1): S21–S29

[13] Hamner MA, Ye Z, Lee RV, Ischemic preconditioning in white matter: magnitude and mechanism[J]. J Neurosci, 2015, 35(47): 15599–15611

[14] Lorenz P, Roychowdhury S, Engelmann M, Oxyresveratrol and resveratrol are potent antioxidants and free radical scavengers: effect on nitrosative and oxidative stress derived from microglial cells[J]. Nitric Oxide, 2003, 9(2): 64–76

[15] Kim HS, Cho IH, Kim JE, Ethyl pyruvate has an anti-inflammatory effect by inhibiting ROS-dependent STAT signaling in activated microglia[J]. Free Radic Biol Med, 2008, 45(7): 950–963

[16] Zhang F, Liu J, Shi JS. Anti-inflammatory activities of resveratrol in the brain: role of resveratrol in microglial activation[J]. Eur J Pharmacol, 2010, 636(1-3): 1–7

[17] Haber M, Abdel Baki SG, Grin'kina NM, Minocycline plus N-acetylcysteine synergize to modulate inflammation and prevent cognitive and memory deficits in a rat model of mild traumatic brain injury[J]. Exp Neurol, 2013, 249: 169–177

[18] Kielian T. Toll-like receptors in central nervous system glial inflammation and homeostasis[J]. J Neurosci Res, 2006, 83(5): 711–730

[19] Aravalli RN, Peterson PK, Lokensgard JR. Toll-like receptors in defense and damage of the central nervous system[J]. J Neuroimmune Pharmacol, 2007, 2(4): 297–312

[20] Crawford DK, Mangiardi M, Tiwari-Woodruff SK. Assaying the functional effects of demyelination and remyelination: revisiting field potential recordings[J]. J Neurosci Methods, 2009, 182(1): 25–33

[21] Reeves TM, Phillips LL, Povlishock JT. Myelinated and unmyelinated axons of the corpus callosum differ in vulnerability and functional recovery following traumatic brain injury[J]. Exp Neurol, 2005, 196(1): 126–137

[22] Medana IM, Esiri MM. Axonal damage: a key predictor of outcome in human CNS diseases[J]. Brain, 2003, 126(Pt 3): 515–530

[23] Streit WJ, Walter SA, Pennell NA. Reactive microgliosis[J]. Prog Neurobiol, 1999, 57(6): 563–581

[24] Kettenmann H. Triggering the brain's pathology sensor[J]. Nat Neurosci, 2006, 9(12): 1463–1464

[25] Kloss CU, Bohatschek M, Kreutzberg GW, Effect of lipopolysaccharide on the morphology and integrin immunoreactivity of ramified microglia in the mouse brain and in cell culture[J]. Exp Neurol, 2001, 168(1): 32–46

[26] Donnelly DJ, Gensel JC, Ankeny DP, An efficient and reproducible method for quantifying macrophages in different experimental models of central nervous system pathology[J]. J Neurosci Methods, 2009, 181(1): 36–44

[27] Aida Y, Kusumoto K, Nakatomi K, An analogue of lipid A and LPS from Rhodobacter sphaeroides inhibits neutrophil responses to LPS by blocking receptor recognition of LPS and by depleting LPS-binding protein in plasma[J]. J Leukoc Biol, 1995, 58(6): 675–682

[28] Kutuzova GD, Albrecht RM, Erickson CM, Diphosphoryl lipid A from Rhodobacter sphaeroides blocks the binding and internalization of lipopolysaccharide in RAW 264.7 cells[J]. J Immunol, 2001, 167(1): 482–489

[29] Zhang J, Liu J, Fox HS, N-methyl-D-aspartate receptor-mediated axonal injury in adult rat corpus callosum[J]. J Neurosci Res, 2013, 91(2): 240–248

[30] Nimmerjahn A, Kirchhoff F, Helmchen F. Resting microglial cells are highly dynamic surveillants of brain parenchyma in vivo[J]. Science, 2005, 308(5726): 1314–1318

[31] Ransohoff RM, Perry VH. Microglial physiology: unique stimuli, specialized responses[J]. Annu Rev Immunol, 2009, 27: 119–145

[32] Block ML, Zecca L, Hong JS. Microglia-mediated neurotoxicity: uncovering the molecular mechanisms[J]. Nat Rev Neurosci, 2007, 8(1): 57–69

[33] Tanaka T, Ueno M, Yamashita T. Engulfment of axon debris by microglia requires p38 MAPK activity[J]. J Biol Chem, 2009, 284(32): 21626–21636

[34] Smith ME. Phagocytosis of myelin in demyelinative disease: a review[J]. Neurochem Res, 1999, 24(2): 261–268

[35] Buxbaum JD, Thinakaran G, Koliatsos V, Alzheimer amyloid protein precursor in the rat hippocampus: transport and processing through the perforant path[J]. J Neurosci, 1998, 18(23): 9629–9637

[36] Kaether C, Skehel P, Dotti CG. Axonal membrane proteins are transported in distinct carriers: a two-color video microscopy study in cultured hippocampal neurons[J]. Mol Biol Cell, 2000, 11(4): 1213–1224

[37] Li GL, Farooque M, Holtz A, Changes of beta-amyloid precursor protein after compression trauma to the spinal cord: an experimental study in the rat using immunohistochemistry[J]. J Neurotrauma, 1995, 12(3): 269–277

[38] Deng Y, Lu J, Sivakumar V, Amoeboid microglia in the periventricular white matter induce oligodendrocyte damage through expression of proinflammatory cytokines via MAP kinase signaling pathway in hypoxic neonatal rats[J]. Brain Pathol, 2008, 18(3): 387–400

[39] Perry VH, Nicoll JA, Holmes C. Microglia in neurodegenerative disease[J]. Nat Rev Neurol, 2010, 6(4): 193–201

[40] Neher JJ, Neniskyte U, Brown GC. Primary phagocytosis of neurons by inflamed microglia: potential roles in neurodegeneration[J]. Front Pharmacol, 2012, 3: 27

Acknowledgments

We warmly thank Dr. Judith Strong (Faculty of University of Cincinnati Medical Center) for her critical reading and scientific comments on this manuscript.

RIGHTS & PERMISSIONS

2018 2018 by the Journal of Biomedical Research.