Notch-Mediated Generation of Monocyte-Derived Langerhans Cells: Phenotype and Function

Lydia Bellmann,Claudia Zelle-Rieser,Paul Milne,Anastasia Resteu,Christoph H Tripp,Natascha Hermann-Kleiter,Viktoria Zaderer,Doris Wilflingseder,Paul Hörtnagl,Maria Theochari,Jessica Schulze,Mareike Rentzsch,Barbara Del Frari,Matthew Collin,Christoph Rademacher,Nikolaus Romani,Patrizia Stoitzner

doi:10.1016/j.jid.2020.05.098

Abstract

Langerhans cells (LCs) in the skin are a first line of defense against pathogens but also play an essential role in skin homeostasis. Their exclusive expression of the C-type lectin receptor Langerin makes them prominent candidates for immunotherapy. For vaccine testing, an easily accessible cell platform would be desirable as an alternative to the time-consuming purification of LCs from human skin. Here, we present such a model and demonstrate that monocytes in the presence of GM-CSF, TGF-β1, and the Notch ligand DLL4 differentiate within 3 days into CD1a+Langerin+cells containing Birbeck granules. RNA sequencing of these monocyte-derived LCs (moLCs) confirmed gene expression of LC-related molecules, pattern recognition receptors, and enhanced expression of genes involved in the antigen-presenting machinery. On the protein level, moLCs showed low expression of costimulatory molecules but prominent expression of C-type lectin receptors. MoLCs can be matured, secrete IL-12p70 and TNF-α, and stimulate proliferation and cytokine production in allogeneic CD4+ and CD8+ T cells. In regard to vaccine testing, a recently characterized glycomimetic Langerin ligand conjugated to liposomes demonstrated specific and fast internalization into moLCs. Hence, these short-term in vitro‒generated moLCs represent an interesting tool to screen LC-based vaccines in the future.

Highlights

Langerhans cells (LCs) are specialized antigen-presenting cells residing in the epidermis of the skin in close contact with neighboring keratinocytes (Romani et al, 2010a)
Notch ligation allows the rapid generation of monocyte-derived LC (moLC) with the expression of Langerin and Birbeck granules To generate moLCs, blood CD14þ monocytes were seeded on a monolayer of OP9-DLL4 stromal cells
The vast majority (74.5% Æ 6.3%) coexpressed Langerin (Figure 1a and c), phenotypically similar to CD1aþLangerinþ LCs isolated from human skin (Supplementary Figure S1c)

Summary

Introduction

Langerhans cells (LCs) are specialized antigen-presenting cells residing in the epidermis of the skin in close contact with neighboring keratinocytes (Romani et al, 2010a). They are found in mucosal, vaginal, and other epithelia (Hovav, 2018). Upon inflammation or pathogen invasion, LCs are activated, migrate to the lymph node, and interact with various T cells (Clausen and Stoitzner, 2015; Romani et al, 2010a; West and Bennett, 2017). Do LCs initiate priming in the lymph node but they have important skin-resident functions such as the interaction with regulatory T cells, resident memory T cells, and NK cells (Ortner et al, 2017; West and Bennett, 2017)

Methods

Results

Conclusion