Interleukin 6-Mediated Endothelial Barrier Disturbances Can Be Attenuated by Blockade of the IL6 Receptor Expressed in Brain Microvascular Endothelial Cells


Compromised blood-brain barrier (BBB) by dysregulation of cellular junctions is a hallmark of many cerebrovascular disorders due to the pro-inflammatory cytokines action. Interleukin 6 (IL6) is implicated in inflammatory processes and in secondary brain injury after subarachnoid hemorrhage (SAH) but its role in the maintenance of cerebral endothelium still requires a precise elucidation. Although IL6 has been shown to exert pro-inflammatory action on brain microvascular endothelial cells (ECs), the expression of one of the IL6 receptors, the IL6R is controversially discussed. In attempt to reach more clarity in this issue, we present here an evident baseline expression of the IL6R in BBB endothelium in vivo and in an in vitro model of the BBB, the cEND cell line. A significantly increased expression of IL6R and its ligand was observed in BBB capillaries 2 days after experimental SAH in mice. In vitro, we saw IL6 administration resulting in an intracellular and extracellular elevation of IL6 protein, which was accompanied by a reduced expression of tight and adherens junctions, claudin-5, occludin, and vascular-endothelial (VE-) cadherin. By functional assays, we could demonstrate IL6-incubated brain ECs to lose their endothelial integrity that can be attenuated by inhibiting the IL6R. Blockade of the IL6R by a neutralizing antibody has reconstituted the intercellular junction expression to the control level and caused a restoration of the transendothelial electrical resistance of the cEND cell monolayer. Our findings add depth to the current understanding of the involvement of the endothelial IL6R in the loss of EC integrity implicating potential therapy options.

This is a preview of subscription content, log in to check access.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6


  1. 1.

    Abbott NJ, Patabendige AA, Dolman DE, Yusof SR, Begley DJ. Structure and function of the blood-brain barrier. Neurobiol Dis 2010;37(1):13–25. doi: PubMed.

    CAS  Article  Google Scholar 

  2. 2.

    Paolinelli R, Corada M, Orsenigo F, Dejana E. The molecular basis of the blood brain barrier differentiation and maintenance. Is it still a mystery? Pharmacol Res. 2011;63(3):165–71.

    CAS  Article  PubMed  Google Scholar 

  3. 3.

    Lampugnani MG, Dejana E. Adherens junctions in endothelial cells regulate vessel maintenance and angiogenesis. Thromb Res. 2007;120(Suppl 2):S1–6.

    Article  PubMed  Google Scholar 

  4. 4.

    Walsh TG, Murphy RP, Fitzpatrick P, Rochfort KD, Guinan AF, Murphy A, et al. Stabilization of brain microvascular endothelial barrier function by shear stress involves VE-cadherin signaling leading to modulation of pTyr-occludin levels. J Cell Physiol. 2011;226(11):3053–63.

    CAS  Article  PubMed  Google Scholar 

  5. 5.

    Dóczi T. The pathogenetic and prognostic significance of blood-brain barrier damage at the acute stage of aneurysmal subarachnoid haemorrhage. Clinical and experimental studies. Acta Neurochir. 1985;77(3-4):110–32.

    Article  PubMed  Google Scholar 

  6. 6.

    Abbott NJ, Friedman A. Overview and introduction: the blood-brain barrier in health and disease. Epilepsia. 2012;53 Suppl 6:1–6.

    Article  PubMed  Google Scholar 

  7. 7.

    Atangana E, Schneider UC, Blecharz K, Magrini S, Wagner J, Nieminen-Kelhä M, et al. Intravascular inflammation triggers intracerebral activated microglia and contributes to secondary brain injury after experimental subarachnoid hemorrhage (eSAH). Transl Stroke Res. 2017;8(2):144–56.

    CAS  Article  PubMed  Google Scholar 

  8. 8.

    Coisne C, Engelhardt B. Tight junctions in brain barriers during central nervous system inflammation. Antioxid Redox Signal. 2011;15(5):1285–303.

    CAS  Article  PubMed  Google Scholar 

  9. 9.

    de Boer AG, Gaillard PJ. Blood-brain barrier dysfunction and recovery. J Neural Transm (Vienna). 2006;113(4):455–62.

    Article  Google Scholar 

  10. 10.

    Förster C, Burek M, Romero IA, Weksler B, Couraud PO, Drenckhahn D. Differential effects of hydrocortisone and TNFalpha on tight junction proteins in an in vitro model of the human blood-brain barrier. J Physiol. 2008;586(7):1937–49.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  11. 11.

    Kimura H, Gules I, Meguro T, Zhang JH. Cytotoxicity of cytokines in cerebral microvascular endothelial cell. Brain Res. 2003;990(1-2):148–56.

    CAS  Article  PubMed  Google Scholar 

  12. 12.

    Abbott NJ. Inflammatory mediators and modulation of blood-brain barrier permeability. Cell Mol Neurobiol. 2000;20:131–47.

    CAS  Article  Google Scholar 

  13. 13.

    Graetz D, Nagel A, Schlenk F, Sakowitz O, Vajkoczy P, Sarrafzadeh A. High ICP as trigger of proinflammatory IL-6 cytokine activation in aneurysmal subarachnoid hemorrhage. Neurol Res. 2010;32(7):728–35.

    CAS  Article  PubMed  Google Scholar 

  14. 14.

    Sarrafzadeh A, Schlenk F, Gericke C, Vajkoczy P. Relevance of cerebral interleukin-6 after aneurysmal subarachnoid hemorrhage. Neurocrit Care. 2010;13(3):339–46.

    CAS  Article  PubMed  Google Scholar 

  15. 15.

    Jüttler E, Tarabin V, Schwaninger M. Interleukin-6 (IL-6): a possible neuromodulator induced by neuronal activity. Neuroscientist. 2002;8(3):268–75.

    Article  PubMed  Google Scholar 

  16. 16.

    Schneider UC, Davids AM, Brandenburg S, Müller A, Elke A, Magrini S, et al. Microglia inflict delayed brain injury after subarachnoid hemorrhage. Acta Neuropathol. 2015;130(2):215–31.

    Article  PubMed  Google Scholar 

  17. 17.

    Heinrich PC, Behrmann I, Haan S, Hermanns HM, Müller-Newen G, Schaper F. Principles of interleukin (IL)-6-type cytokine signalling and its regulation. Biochem J. 2003;374(1):1–20.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  18. 18.

    Atangana EN, Homburg D, Vajkoczy P, Schneider UC. Mouse cerebral magnetic resonance imaging fails to visualize brain volume changes after experimental subarachnoid hemorrhage. Acta Neurochir. 2015;157(1):37–42.

    Article  PubMed  Google Scholar 

  19. 19.

    Egashira Y, Shishido H, Hua Y, Keep RF, Xi G. New grading system based on magnetic resonance imaging in a mouse model of subarachnoid hemorrhage. Stroke. 2015;46(2):582–4.

    Article  PubMed  Google Scholar 

  20. 20.

    Ghori A, Freimann FB, Nieminen-Kelhä M, Kremenetskaia I, Gertz K, Endres M, et al. EphrinB2 activation enhances vascular repair mechanisms and reduces brain swelling after mild cerebral ischemia. Arterioscler Thromb Vasc Biol. 2017;37(5):867–78.

    CAS  Article  PubMed  Google Scholar 

  21. 21.

    Wu Q, Qi L, Li H, Mao L, Yang M, Xie R, et al. Roflumilast reduces cerebral inflammation in a rat model of experimental subarachnoid hemorrhage. Inflammation. 2017;40(4):1245–53.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  22. 22.

    Del Vecchio G, Tscheik C, Tenz K, Helms HC, Winkler L, Blasig R, et al. Sodium caprate transiently opens claudin-5-containing barriers at tight junctions of epithelial and endothelial cells. Mol Pharm. 2012;9(9):2523–33.

    CAS  Article  PubMed  Google Scholar 

  23. 23.

    Förster C, Silwedel C, Golenhofen N, Burek M, Kietz S, Mankertz J, et al. Occludin as direct target for glucocorticoid-induced improvement of blood-brain barrier properties in a murine in vitro system. J Physiol. 2005;565(2):475–86.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  24. 24.

    Fagart J, Wurtz JM, Souque A, Hellal-Levy C, Moras D, Rafestin-Oblin ME. Antagonism in the human mineralocorticoid receptor. EMBO J. 1998;17(12):3317–25.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  25. 25.

    Blecharz KG, Frey D, Schenkel T, Prinz V, Bedini G, Krug SM, et al. Autocrine release of angiopoietin-2 mediates cerebrovascular disintegration in Moyamoya disease. J Cereb Blood Flow Metab. 2016;37:1527–39.

    Article  Google Scholar 

  26. 26.

    Rochfort KD, Collins LE, Murphy RP, Cummins PM. Downregulation of blood-brain barrier phenotype by proinflammatory cytokines involves NADPH oxidase-dependent ROS generation: consequences for interendothelial adherens and tight junctions. PLoS One. 2014;9(7):e101815.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  27. 27.

    Shalaby MR, Waage A, Aarden L, Espevik T. Endotoxin, tumor necrosis factor-alpha and interleukin 1 induce interleukin 6 production in vivo. Clin Immunol Immunopathol. 1989;53(3):488–98.

    CAS  Article  PubMed  Google Scholar 

  28. 28.

    Vallières L, Rivest S. Regulation of the genes encoding interleukin-6, its receptor, and gp130 in the rat brain in response to the immune activator lipopolysaccharide and the proinflammatory cytokine interleukin-1beta. J Neurochem. 1997;69(4):1668–83.

    Article  Google Scholar 

  29. 29.

    Choi JM, Rotimi OO, O'Carroll SJ, Nicholson LF. IL-6 stimulates a concentration-dependent increase in MCP-1 in immortalised human brain endothelial cells. F1000Res. 2016;5:270.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  30. 30.

    Nilsson MB, Langley RR, Fidler IJ. Interleukin-6, secreted by human ovarian carcinoma cells, is a potent proangiogenic cytokine. Cancer Res. 2005;65(23):10794–800.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  31. 31.

    Eskilsson A, Mirrasekhian E, Dufour S, Schwaninger M, Engblom D, Blomqvist A. Immune-induced fever is mediated by IL-6 receptors on brain endothelial cells coupled to STAT3-dependent induction of brain endothelial prostaglandin synthesis. J Neurosci. 2014;34(48):15957–61.

    CAS  Article  PubMed  Google Scholar 

  32. 32.

    Rochfort KD, Collins LE, McLoughlin A, Cummins PM. Tumour necrosis factor-α-mediated disruption of cerebrovascular endothelial barrier integrity in vitro involves the production of proinflammatory interleukin-6. J Neurochem. 2016;136(3):564–72.

    CAS  Article  PubMed  Google Scholar 

  33. 33.

    Duchini A, Govindarajan S, Santucci M, Zampi G, Hofman FM. Effects of tumor necrosis factor-alpha and interleukin-6 on fluid-phase permeability and ammonia diffusion in CNS-derived endothelial cells. J Investig Med. 1996;44(8):474–82.

    CAS  PubMed  Google Scholar 

  34. 34.

    Blecharz KG, Drenckhahn D, Förster CY. Glucocorticoids increase VE-cadherin expression and cause cytoskeletal rearrangements in murine brain endothelial cEND cells. J Cereb Blood Flow Metab. 2008;28(6):1139–49.

    CAS  Article  PubMed  Google Scholar 

  35. 35.

    Ueda O, Tateishi H, Higuchi Y, Fujii E, Kato A, Kawase Y, et al. Novel genetically-humanized mouse model established to evaluate efficacy of therapeutic agents to human interleukin-6 receptor. Sci Rep. 2013;3(1):1196.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  36. 36.

    Feist E, Burmester GR. Small molecules targeting JAKs—a new approach in the treatment of rheumatoid arthritis. Rheumatology (Oxford). 2013;52(8):1352–7.

    CAS  Article  Google Scholar 

  37. 37.

    Su JL, Lai KP, Chen CA, Yang CY, Chen PS, Chang CC, et al. A novel peptide specifically binding to interleukin-6 receptor (gp80) inhibits angiogenesis and tumor growth. Cancer Res. 2005;65(11):4827–35.

    CAS  Article  PubMed  Google Scholar 

  38. 38.

    Kitaba S, Murota H, Terao M, Azukizawa H, Terabe F, Shima Y, et al. Blockade of interleukin-6 receptor alleviates disease in mouse model of scleroderma. Am J Pathol. 2012;180(1):165–76.

    CAS  Article  PubMed  Google Scholar 

  39. 39.

    Axmann R, Böhm C, Krönke G, Zwerina J, Smolen J, Schett G. Inhibition of interleukin-6 receptor directly blocks osteoclast formation in vitro and in vivo. Arthritis Rheum. 2009;60(9):2747–56.

    CAS  Article  PubMed  Google Scholar 

  40. 40.

    Kobara M, Noda K, Kitamura M, Okamoto A, Shiraishi T, Toba H, et al. Antibody against interleukin-6 receptor attenuates left ventricular remodelling after myocardial infarction in mice. Cardiovasc Res. 2010;87(3):424–30.

    CAS  Article  PubMed  Google Scholar 

Download references


This study was financially supported by Deutsche Forschungsgemeinschaft (SFB TRR43) and Bundesministerium für Bildung und Forschung (Center for Stroke Research Berlin) to PV.

The authors are grateful to Irina Kremenetskaia for excellent technical assistance.

Author information




KGBL, UCS, and PV designed the experiments and supervised the project. KGBL, JW, AF, MNK, and JR collected, analyzed, and interpreted the data. KGBL and PV interpreted the data and critically drafted and/or revised the manuscript. All authors were involved in interpretation of the data and critical revision of the manuscript, have approved the final version of the manuscript, and agree to be accountable for all aspects of the work.

Corresponding author

Correspondence to Peter Vajkoczy.

Ethics declarations

Conflict of Interest

The authors declare that no conflict of interest exists.

Ethical Approval

All applicable international, national, and/or institutional guidelines for the care and use of animals were followed.

Electronic supplementary material

Fig S1

(DOCX 144 kb)

Fig S2

(DOCX 109 kb)

Fig S3

(DOCX 89 kb)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Blecharz-Lang, K.G., Wagner, J., Fries, A. et al. Interleukin 6-Mediated Endothelial Barrier Disturbances Can Be Attenuated by Blockade of the IL6 Receptor Expressed in Brain Microvascular Endothelial Cells. Transl. Stroke Res. 9, 631–642 (2018).

Download citation


  • Blood-brain barrier
  • Cytokine
  • Endothelial cells
  • Inflammation
  • Interleukin 6
  • Subarachnoid hemorrhage