ePoster Presentation 49th Annual Scientific Meeting of the Australian and New Zealand Society for Immunology 2021

HSV-1 infects Langerhans cells and the novel epidermal dendritic cell, Epi-cDC2s, via different entry pathways (#245)

Naomi R Truong 1 2 , Kirstie M Bertram 1 2 , Jacinta B Smith 1 2 , Kerrie J Sandgren 1 2 , Konrad L Feng 1 2 , Jason J Herbert 1 2 , Hafsa Rana 1 2 , Kevin Danastas 1 2 , Monica Miranda-Saksena 1 2 , Andrew N Harman 1 3 , Anthony L Cunningham 1 2
  1. Westmead Institute for Medical Research, Westmead, NSW, Australia
  2. The Westmead Clinical School, Faculty of Medicine and Health, The University of Sydney, Westmead, NSW, Australia
  3. The School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Westmead, NSW, Australia

Skin mononuclear phagocytes (MNPs) are the first immune cells to interact with HSV. We previously showed that human Langerhans cells (LCs) became infected with HSV, emigrated to the dermis, underwent apoptosis and clustered with subsets of dermal dendritic cells (dDCs), facilitating a “viral antigen relay” where the infected LCs containing HSV were taken up by dDCs [1]. In addition to LCs, we recently described a second epidermal MNP population in human anogenital epidermis that are closely related to dermal conventional DC type 2 (cDC2), called Epi-cDC2s. These cells express CD1a and some langerin in common with LCs, but are distinguished by their expression of CD11c, which is absent on human LCs [2]. Here, we compared the responses of Epi-cDC2s and LCs to HSV-1 infection. In topically HSV-1 infected epidermal explants, we saw that both LCs and Epi-cDC2s interacted with HSV-1 and infected keratinocytes. Isolated Epi-cDC2s supported higher levels of HSV-1 infection than LCs in vitro, including immediate early, structural and true late HSV-1 proteins, which were inhibited by acyclovir. Both MNP subtypes expressed similar levels of HVEM and nectin-1 and showed similar levels of initial uptake. However, we found that HSV-1 utilised different entry pathways in each cell type. HSV-1 predominantly infected LCs via pH-dependent endocytosis, inhibited by bafilomycin A, whereas Epi-cDC2s were mainly infected via a pH-independent pathway, inhibited by actin and cholesterol inhibitors. This difference in entry pathway may contribute to the enhanced infection of Epi-cDC2s. HSV-1 infection induced apoptosis in both cell types, identified by caspase-3 expression, reducing extracellular HSV concentrations in the supernatant [3]. Epi-cDC2s may follow the same dermal migration and uptake by dermal DCs as previously shown for LCs, although they may stimulate responses via different pathways. This knowledge may help guide future HSV vaccine development and adjuvant targeting.

  1. Kim et al., (2015) PLOS Pathogens PMID:25875649
  2. Bertram et al., (2019) Nature Communications PMID:31227717
  3. Bertram, Truong et al., (2021) PLOS Pathogens PMID:33905459