SARS-CoV-2 causes human BBB injury and neuroinflammation indirectly in a linked organ chip platform

  1. Peng Wang
  2. Lin Jin
  3. Min Zhang
  4. Yunsong Wu
  5. Zilei Duan
  6. Wenwen Chen
  7. Chaoming Wang
  8. Zhiyi Liao
  9. Jianbao Han
  10. Yingqi Guo
  11. Yaqiong Guo
  12. Yaqing Wang
  13. Ren Lai
  14. Jianhua Qin

Reviewed by

Read the full article

Listed in

Log in to save this article

Abstract

COVID-19 is a multi-system disease affecting many organs outside of the lungs, and patients generally develop varying degrees of neurological symptoms. Whereas, the pathogenesis underlying these neurological manifestations remains elusive. Although in vitro models and animal models are widely used in studies of SARS-CoV-2 infection, human organ models that can reflect the pathological alterations in a multi-organ context are still lacking. In this study, we propose a new strategy to probe the effects of SARS-CoV-2 on human brains in a linked alveolus-BBB organ chip platform. The new multi-organ platform allows to recapitulate the essential features of human alveolar-capillary barrier and blood-brain barrier in a microfluidic condition by co-culturing the organ-specific cells. The results reveal direct SARS-CoV-2 exposure has no obvious effects on BBB chip alone. While, infusion of endothelial medium from infected alveolus chips can cause BBB dysfunction and neuroinflammation on the linked chip platform, including brain endothelium disruption, glial cell activation and inflammatory cytokines release. These new findings suggest that SARS-CoV-2 could induce neuropathological alterations, which might not result from direct viral infection through hematogenous route, but rather likely from systemic inflammation following lung infection. This work provides a new strategy to study the virus-host interaction and neuropathology at an organ-organ context, which is not easily obtained by other in vitro models. This will facilitate to understand the neurological pathogenesis in SARS-CoV-2 and accelerate the development of new therapeutics.

SUMMARY

  • A linked human alveolus-BBB chip platform is established to explore the influences of SARS-CoV-2 on human brains in an organ-organ context.

  • SARS-CoV-2 infection could induce BBB injury and neuroinflammation.

  • The neuropathological changes are caused by SARS-CoV-2 indirectly, which might be mediated by systemic inflammation following lung infection, but probably not by direct viral neuroinvasion.

    • Article activity feed

    1. ScreenIT

      SciScore for 10.1101/2021.10.05.463205: (What is this?)

      Please note, not all rigor criteria are appropriate for all manuscripts.

      Table 1: Rigor

      Ethicsnot detected.
      Sex as a biological variablenot detected.
      Randomizationnot detected.
      BlindingDuring the experiment and assessing the outcome, the investigators were blinded to the group allocation.
      Power Analysisnot detected.
      Cell Line Authenticationnot detected.

      Table 2: Resources

      Experimental Models: Cell Lines
      SentencesResources
      HULEC-5a cells were purchased from Procell Corporation (no. CL-0565; introduced from ATCC Company), and maintained in a special pulmonary endothelial medium (Procell Corporation, no.
      HULEC-5a
      suggested: ATCC Cat# CRL-3244, RRID:CVCL_0A11)
      The virus was propagated in Vero E6 cells, and viral titer was determined by a TCID50 assay on Vero E6 cells.
      Vero E6
      suggested: None
      Then, HMC3 cells (∼5×104 cells/chip) were seeded on the bottom side of lower channel, and HBMEC cells (∼1×105 cells/chip) were seeded into the upper channel, respectively.
      HMC3
      suggested: ATCC Cat# CRL-3304, RRID:CVCL_II76)
      Cytokines in culture supernatants, including IL-6, MCP-1 (CCL2), G-CSF, IFN-α2, IL-2, IFN-γ, IL-7, IL-1RA, IL-8 (CXCL8)
      MCP-1
      suggested: None
      Software and Algorithms
      SentencesResources
      Image processing was done using ImageJ software (NIH)
      ImageJ
      suggested: (ImageJ, RRID:SCR_003070)
      Statistical analyses: Data were collected by Excel (Microsoft) software.
      Excel
      suggested: None
      The GraphPad Prism 6 software was used for data statistical analysis.
      GraphPad Prism
      suggested: (GraphPad Prism, RRID:SCR_002798)

      Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

      Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
      In regard to the viral neuroinvasion, several organoid models have been utilized to investigate the SARS-CoV-2 neurotropism and viral entry route to human brains 19-24, however, some limitations constrain interpretation of these studies. As these brain organoids have not realized vascularization and lack a functional BBB interface, making it difficult to accurately recapitulate the viral exposure in physiological state. Besides, no immune cells (such as peripheral blood immune cells, microglial cells) were present in these brain organoids, which made it unsuitable to evaluate the host immune responses and the impacts of systematic inflammation on brain following SARS-CoV-2 infection. Compared with other in vitro models, the major advantage of this platform is the capability to introduce various of cell types or tissues according to research needs, such as immune cells, tissue interfaces and vasculatures. As for COVID-19, although immune cells and vascular endothelial cells are not the primary attack targets for virus, they contribute a lot to disease progression and some lifethreatening complications, such as inflammatory responses, systemic vasculitis and venous thromboembolism et al. 50-52. In this model system, peripheral blood immune cells were introduced into the alveolus chips, and robust inflammatory cytokines release was detected following SARS-CoV-2 infection, mimicking the cytokine storms commonly happening in severe COVID-19 cases. In our previous study on human al...

      Results from TrialIdentifier: No clinical trial numbers were referenced.

      Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

      Results from JetFighter: Please consider improving the rainbow (“jet”) colormap(s) used on pages 19, 20 and 21. At least one figure is not accessible to readers with colorblindness and/or is not true to the data, i.e. not perceptually uniform.

      Results from rtransparent:
      • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
      • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
      • No protocol registration statement was detected.

      Results from scite Reference Check: We found no unreliable references.

      About SciScore

      SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

    2. Version published to 10.1101/2021.10.05.463205v1 on bioRxiv