Poster Presentation Lorne Infection and Immunity 2020

A novel role of apoptotic dendritic cells as antigen presenting entities within immune settings (#158)

Amy L Hodge 1 , Amy A Baxter 1 , Sarah Caruso 1 , Georgia K Atkin-Smith 1 , Lanzhou Jiang 1 , Jieru Deng 1 , Weisan Chen 1 , Ivan K.H. Poon 1
  1. La Trobe Institute for Molecular Science, Melbourne, Australia

Apoptosis is a highly regulated and controlled process essential for efficient cell clearance and the maintenance of tissue homeostasis. The disassembly of an apoptotic cell is characterized by the generation of small membrane-bound extracellular vesicles, termed apoptotic bodies (ApoBDs), which have been found to carry biomolecules (i.e., nucleic acids and proteins) and thereby are suggested to have a pivotal role in mediating intercellular communication(1). The generation of ApoBDs has been discovered within cells of the immune system such as T cells and monocytes. However, the importance of the apoptotic cell disassembly process has not been fully elucidated in dendritic cells (DCs), essential antigen presenting cells that help bridge the innate and adaptive immune systems. Within the present study a series of cell biological analyses using in vitro and ex vivo human and murine DCs was conducted to identify the function of DC-derived ApoBDs in an Influenza A virus (IAV) model. Upon initiation of apoptosis, time lapse microscopy and flow cytometry analyses revealed that DCs undergo apoptotic cell disassembly through dynamic membrane blebbing, membrane protrusion formation and the generation of ApoBDs in a Rho-associated kinase 1 (ROCK1) dependent manner. Furthermore, apoptotic DCs and DC-derived ApoBDs retain essential immune signalling molecules required for efficient antigen presentation and T cell activation, including Major Histocompatibility Complex (MHC) Class I and II, and costimulatory molecules CD80 and CD86. To determine the functional role of DC-derived ApoBDs during viral infection, an ex vivo model of T cell activation was performed. IAV-infected DCs underwent apoptosis and generated ApoBDs that were able to activate CD8+ T cells, as demonstrated by the release of INF-γ. These findings provide insights into a potential novel role of DC-derived ApoBDs as antigen presenting entities capable of propagating immune signalling during infection.

 

  1. Atkin-Smith G.K. & Poon, I.K.H. (2017). “Disassembly of the dying: mechanisms and functions.” Trends Cell Biol 27 (2): 151-162.