The brain’s blood microvessels restrict the exchange of substances between the blood and brain tissue through the blood-brain barrier (BBB). Methyl-glyoxal (MG), a byproduct of glucose metabolism, contributes to the formation of advanced glycation end products (AGEs) and disrupts the BBB, which is associated with neurodegenerative diseases. L-Theanine (TA), an amino acid found in green tea with antioxidant properties, may protect the BBB. This study aimed to determine whether MG increases reactive oxygen species (ROS) and permeability by reducing tight junction proteins in human cerebral microvascular endothelial cells (hCMEC/d3), and whether TA pretreatment can counteract these effects. Our findings demonstrated that MG treatment led to increased BBB permeability, decreased transendothelial electrical resistance (TEER) values to 39% of control levels, reduced expression of Claudin-5 to 53% and Occludin to 69% of control levels, and elevated intracellular ROS levels. TA pretreatment restored barrier integrity, preserved tight junction protein expression, and decreased ROS accumulation to levels comparable to control levels. These findings suggest that TA effectively prevents MG-induced BBB dysfunction by reducing oxidative stress and maintaining tight junction proteins, showing promise as a protective agent for the BBB in conditions associated with elevated MG and AGEs.
References
[1]
Kaya, M. and Ahishali, B. (2020) Basic Physiology of the Blood-Brain Barrier in Health and Disease: A Brief Overview. TissueBarriers, 9, Article ID: 1840913. https://doi.org/10.1080/21688370.2020.1840913
[2]
Sweeney, M.D., Sagare, A.P. and Zlokovic, B.V. (2018) Blood-Brain Barrier Breakdown in Alzheimer Disease and Other Neurodegenerative Disorders. NatureReviewsNeurology, 14, 133-150. https://doi.org/10.1038/nrneurol.2017.188
[3]
Tajes, M., Ramos-Fernández, E., Weng-Jiang, X., Bosch-Morató, M., Guivernau, B., Eraso-Pichot, A., et al. (2014) The Blood-Brain Barrier: Structure, Function and Therapeutic Approaches to Cross It. MolecularMembraneBiology, 31, 152-167. https://doi.org/10.3109/09687688.2014.937468
[4]
Lai, S.W.T., Lopez Gonzalez, E.D.J., Zoukari, T., Ki, P. and Shuck, S.C. (2022) Methylglyoxal and Its Adducts: Induction, Repair, and Association with Disease. ChemicalResearchinToxicology, 35, 1720-1746. https://doi.org/10.1021/acs.chemrestox.2c00160
[5]
Schalkwijk, C.G., van Bezu, J., van der Schors, R.C., Uchida, K., Stehouwer, C.D.A. and van Hinsbergh, V.W.M. (2006) Heat-Shock Protein 27 Is a Major Methylglyoxal-Modified Protein in Endothelial Cells. FEBSLetters, 580, 1565-1570. https://doi.org/10.1016/j.febslet.2006.01.086
[6]
Ott, C., Jacobs, K., Haucke, E., Navarrete Santos, A., Grune, T. and Simm, A. (2014) Role of Advanced Glycation End Products in Cellular Signaling. RedoxBiology, 2, 411-429. https://doi.org/10.1016/j.redox.2013.12.016
[7]
Kalapos, M.P. (2008) The Tandem of Free Radicals and Methylglyoxal. Chemico-BiologicalInteractions, 171, 251-271. https://doi.org/10.1016/j.cbi.2007.11.009
[8]
Keenan, E.K., Finnie, M.D.A., Jones, P.S., Rogers, P.J. and Priestley, C.M. (2011) How Much Theanine in a Cup of Tea? Effects of Tea Type and Method of Preparation. FoodChemistry, 125, 588-594. https://doi.org/10.1016/j.foodchem.2010.08.071
[9]
Sugiyama, T. and Sadzuka, Y. (2004) Theanine, a Specific Glutamate Derivative in Green Tea, Reduces the Adverse Reactions of Doxorubicin by Changing the Glutathione Level. CancerLetters, 212, 177-184. https://doi.org/10.1016/j.canlet.2004.03.040
[10]
Deng, Y., Xiao, W., Chen, L., Liu, Q., Liu, Z. and Gong, Z. (2016) In Vivo Antioxidative Effects of L-Theanine in the Presence or Absence of Escherichia Coli-Induced Oxidative Stress. JournalofFunctionalFoods, 24, 527-536. https://doi.org/10.1016/j.jff.2016.04.029
[11]
Li, Z., Chen, L., Huang, Z., Jia, G., Zhao, H., Liu, G., et al. (2024) Supplementation with L-Theanine Promotes Intestinal Antioxidant Ability via Nrf2 Signaling Pathway in Weaning Piglets and H2O2-Induced IPEC-J2 Cells. JournalofFunctionalFoods, 121, Article ID: 106433. https://doi.org/10.1016/j.jff.2024.106433
[12]
Zeng, L., Lin, L., Chen, L., Xiao, W. and Gong, Z. (2021) L-theanine Ameliorates D-galactose-Induced Brain Damage in Rats via Inhibiting AGE Formation and Regulating Sirtuin1 and BDNF Signaling Pathways. OxidativeMedicineandCellularLongevity, 2021, Article ID: 8850112. https://doi.org/10.1155/2021/8850112
[13]
Noguchi-Shinohara, M., Yuki, S., Dohmoto, C., Ikeda, Y., Samuraki, M., Iwasa, K., et al. (2014) Consumption of Green Tea, but Not Black Tea or Coffee, Is Associated with Reduced Risk of Cognitive Decline. PLOSONE, 9, e96013. https://doi.org/10.1371/journal.pone.0096013
[14]
Kuriyama, S., Hozawa, A., Ohmori, K., Shimazu, T., Matsui, T., Ebihara, S., et al. (2006) Green Tea Consumption and Cognitive Function: A Cross-Sectional Study from the Tsurugaya Project. TheAmericanJournalofClinicalNutrition, 83, 355-361. https://doi.org/10.1093/ajcn/83.2.355
[15]
Baba, Y., Inagaki, S., Nakagawa, S., Kaneko, T., Kobayashi, M. and Takihara, T. (2021) Effects of L-Theanine on Cognitive Function in Middle-Aged and Older Subjects: A Randomized Placebo-Controlled Study. JournalofMedicinalFood, 24, 333-341. https://doi.org/10.1089/jmf.2020.4803
[16]
Gomes, A., Fernandes, E. and Lima, J.L.F.C. (2005) Fluorescence Probes Used for Detection of Reactive Oxygen Species. JournalofBiochemicalandBiophysicalMethods, 65, 45-80. https://doi.org/10.1016/j.jbbm.2005.10.003
[17]
Kanda, Y. (2012) Investigation of the Freely Available Easy-To-Use Software ‘EZR’ for Medical Statistics. BoneMarrowTransplantation, 48, 452-458. https://doi.org/10.1038/bmt.2012.244
[18]
Chiou, T., Zhang, J., Ferrans, V.J. and Tzeng, W. (1997) Cardiac and Renal Toxicity of Menadione in Rat. Toxicology, 124, 193-202. https://doi.org/10.1016/s0300-483x(97)00162-5
[19]
Tenório, M.C.D.S., Graciliano, N.G., Moura, F.A., Oliveira, A.C.M.D. and Goulart, M.O.F. (2021) N-Acetylcysteine (NAC): Impacts on Human Health. Antioxidants, 10, Article 967. https://doi.org/10.3390/antiox10060967
[20]
Fukunaga, M., Miyata, S., Liu, B.F., Miyazaki, H., Hirota, Y., Higo, S., et al. (2004) Methylglyoxal Induces Apoptosis through Activation of P38 MAPK in Rat Schwann Cells. BiochemicalandBiophysicalResearchCommunications, 320, 689-695. https://doi.org/10.1016/j.bbrc.2004.06.011
[21]
Hou, S., Nori, P., Fang, J. and Vaca, C.E. (1995) Methylglyoxal Induces HPRT Mutation and DNA Adducts in Human T-Lymphocytes in Vitro. EnvironmentalandMolecularMutagenesis, 26, 286-291. https://doi.org/10.1002/em.2850260404
[22]
Pischetsrieder, M., Seidel, W., Münch, G. and Schinzel, R. (1999) N2-(1-Carboxyethyl)Deoxyguanosine, a Nonenzymatic Glycation Adduct of DNA, Induces Single-Strand Breaks and Increases Mutation Frequencies. BiochemicalandBiophysicalResearchCommunications, 264, 544-549. https://doi.org/10.1006/bbrc.1999.1528
[23]
Zhou, X., Weng, J., Xu, J., Xu, Q., Wang, W., Zhang, W., et al. (2018) Mdia1 Is Crucial for Advanced Glycation End Product-Induced Endothelial Hyperpermeability. CellularPhysiologyandBiochemistry, 45, 1717-1730. https://doi.org/10.1159/000487780
[24]
Oldendorf, W.H., Cornford, M.E. and Brown, W.J. (1977) The Large Apparent Work Capability of the Blood-Brain Barrier: A Study of the Mitochondrial Content of Capillary Endothelial Cells in Brain and Other Tissues of the Rat. AnnalsofNeurology, 1, 409-417. https://doi.org/10.1002/ana.410010502
[25]
Wautier, M., Chappey, O., Corda, S., Stern, D.M., Schmidt, A.M. and Wautier, J. (2001) Activation of NADPH Oxidase by AGE Links Oxidant Stress to Altered Gene Expression via Rage. AmericanJournalofPhysiology-EndocrinologyandMetabolism, 280, E685-E694. https://doi.org/10.1152/ajpendo.2001.280.5.e685
[26]
Coughlan, M.T., Thorburn, D.R., Penfold, S.A., Laskowski, A., Harcourt, B.E., Sourris, K.C., et al. (2009) Rage-induced Cytosolic ROS Promote Mitochondrial Superoxide Generation in Diabetes. JournaloftheAmericanSocietyofNephrology, 20, 742-752. https://doi.org/10.1681/asn.2008050514
[27]
Liu, C., Cao, B., Zhang, Q., Zhang, Y., Chen, X., Kong, X., et al. (2020) Inhibition of Thioredoxin 2 by Intracellular Methylglyoxal Accumulation Leads to Mitochondrial Dysfunction and Apoptosis in INS-1 Cells. Endocrine, 68, 103-115. https://doi.org/10.1007/s12020-020-02191-x
[28]
Kim, D., Kim, K., Kim, J., Kim, E. and Bae, O. (2020) Methylglyoxal-Induced Dysfunction in Brain Endothelial Cells via the Suppression of Akt/HIF-1α Pathway and Activation of Mitophagy Associated with Increased Reactive Oxygen Species. Antioxidants, 9, Article 820. https://doi.org/10.3390/antiox9090820
[29]
Kim, T.I., Lee, Y.K., Park, S.G., Choi, I.S., Ban, J.O., Park, H.K., et al. (2009) L-theanine, an Amino Acid in Green Tea, Attenuates β-Amyloid-Induced Cognitive Dysfunction and Neurotoxicity: Reduction in Oxidative Damage and Inactivation of ERK/p38 Kinase and NF-κB Pathways. FreeRadicalBiologyandMedicine, 47, 1601-1610. https://doi.org/10.1016/j.freeradbiomed.2009.09.008
[30]
Aragonès, G., Rowan, S., Francisco, S.G., Whitcomb, E.A., Yang, W., Perini-Villanueva, G., et al. (2021) The Glyoxalase System in Age-Related Diseases: Nutritional Intervention as Anti-Ageing Strategy. Cells, 10, Article 1852. https://doi.org/10.3390/cells10081852
[31]
Whiting, P.H., Kalansooriya, A., Holbrook, I., Haddad, F. and Jennings, P.E. (2008) The Relationship between Chronic Glycaemic Control and Oxidative Stress in Type 2 Diabetes Mellitus. BritishJournalofBiomedicalScience, 65, 71-74. https://doi.org/10.1080/09674845.2008.11732800
[32]
Morgenstern, J., Katz, S., Krebs-Haupenthal, J., Chen, J., Saadatmand, A., Cortizo, F.G., et al. (2020) Phosphorylation of T107 by Camkiiδ Regulates the Detoxification Efficiency and Proteomic Integrity of Glyoxalase 1. CellReports, 32, Article ID: 108160. https://doi.org/10.1016/j.celrep.2020.108160
[33]
Sharp, C.D., Hines, I., Houghton, J., Warren, A., Jackson, T.H., Jawahar, A., et al. (2003) Glutamate Causes a Loss in Human Cerebral Endothelial Barrier Integrity through Activation of NMDA Receptor. AmericanJournalofPhysiology-HeartandCirculatoryPhysiology, 285, H2592-H2598. https://doi.org/10.1152/ajpheart.00520.2003
[34]
Yamamoto, S., Kimura, T., Tachiki, T., Anzai, N., Sakurai, T. and Ushimaru, M. (2012) The Involvement of L-Type Amino Acid Transporters in Theanine Transport. Bioscience, Biotechnology, andBiochemistry, 76, 2230-2235. https://doi.org/10.1271/bbb.120519
[35]
Yokogoshi, H., Kobayashi, M., Mochizuki, M. and Terashima, T. (1998) Effect of Theanine, r-Glutamylethylamide, on Brain Monoamines and Striatal Dopamine Re-lease in Conscious Rats. NeurochemicalResearch, 23, 667-673. https://doi.org/10.1023/a:1022490806093
[36]
Phumsombat, P., Sano, C., Ikezoe, H., Hayashi, J., Itoh, T., Hibi, T., et al. (2020) Efficient Production of L-Theanine Using Immobilized Recombinant Escherichia coli Cells Expressing a Modified γ-Glutamyltranspeptidase Gene from Pseudomonas nitroreducens. AdvancesinBiologicalChemistry, 10, 157-171. https://doi.org/10.4236/abc.2020.106012
[37]
Griep, L.M., Wolbers, F., de Wagenaar, B., ter Braak, P.M., Weksler, B.B., Romero, I.A., et al. (2012) BBB on CHIP: Microfluidic Platform to Mechanically and Biochemically Modulate Blood-Brain Barrier Function. BiomedicalMicrodevices, 15, 145-150. https://doi.org/10.1007/s10544-012-9699-7
[38]
Lowe, G.D.O., Lowe, J.M., Drummond, M.M., Reith, S., Belch, J.J.F., Kesson, C.M., et al. (1980) Blood Viscosity in Young Male Diabetics with and without Retinopathy. Diabetologia, 18, 359-363. https://doi.org/10.1007/bf00276814