Mechanosensing modulates dendritic cell function and metabolism

  • Author / Creator
    Chu, Kevin
  • Dendritic cells (DCs) are antigen presenting cells critical for the initiation of the adaptive immune response. As such, DCs continually circulate the body to survey for foreign antigen in the periphery. DCs encounter a milieu of environmental cues within the traversed microenvironment that can modulate their metabolism and function during inflammation or infection. DC signaling in response to cytokine and pattern recognition receptor stimulation have been extensively characterized. However, DCs also encounter non-immunological cues from the microenvironment that may contribute to the collective regulation of the immune response. A less well studied non-immunological cue is tension exerted by substrate stiffness. In early experiments, our collaborators observed substrate tension could modulate DC cytokine production and activation. In response to tension, DCs also upregulated the expression of TAZ, a transcription co-activator. TAZ is involved in mechanosensing in non-immune cell types and has a homolog known as YAP with similar functionality, hinting that DC mechanosensing may involve YAP/TAZ signaling. In addition, through enrichment analysis, we found that respiratory diseases were strongly predicted to be associated with tensional changes to DC biology.
    My research aims to expand on these observations using an in vitro culturing protocol whereby bone-marrow derived DCs (BMDCs) are grown on substrates engineered to a stiffness of 2 or 50 kPa, or on plastic only conditions. In my study, I examined whether substrate stiffness could modulate DC antigen presentation and metabolism, as DC maturation and function are intimately connected with metabolic changes. To study the involvement of YAP/TAZ on DC mechanosensing in a respiratory context, we adopted an influenza model. In this model, I examined the day 9 antiviral response in mice with DC specific deletion of YAP/TAZ after immunization with mouse adapted H1N1 influenza. Overall, I found that BMDCs grown on plastic were better at activating T cells, and the effects of substrate stiffness on DC maturation may be a reversible process. Furthermore, DCs conditioned on stiff substrates displayed increased glycolysis and oxidative phosphorylation, suggesting DC metabolism could be modulated by substrate stiffness. As YAP/TAZ translocate into the nucleus upon activation, I incorporated image flow cytometry to probe for the translocation of YAP/TAZ in DCs in response to tension. BMDCs conditioned on 50 kPa and plastic demonstrate a trend of increasing nuclear YAP/TAZ translocation, hinting at the involvement of YAP/TAZ in DC mechanosensing. Interestingly, despite this observation and tension induced upregulation of TAZ in BMDCs, the deletion of YAP/TAZ in DCs did not impair day 9 antiviral response.

  • Subjects / Keywords
  • Graduation date
    Spring 2022
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.