Biting Off What Can Be Chewed: Trogocytosis in Health, Infection, and Disease

Abstract

Trogocytosis is part of an emerging, exciting theme of cell-cell interactions both within and between species, and it is relevant to host-pathogen interactions in many different contexts. Trogocytosis is a process in which one cell physically extracts and ingests “bites” of cellular material from another cell. It was first described in eukaryotic microbes, where it was uncovered as a mechanism by which amoebae kill cells. Trogocytosis is potentially a fundamental form of eukaryotic cell-cell interaction, since it also occurs in multicellular organisms, where it has functions in the immune system, in the central nervous system, and during development. There are numerous scenarios in which trogocytosis occurs and an ever-evolving list of functions associated with this process. Many aspects of trogocytosis are relevant to microbial pathogenesis. It was recently discovered that immune cells perform trogocytosis to kill Trichomonas vaginalis parasites. Additionally, through trogocytosis, Entamoeba histolytica acquires and displays human cell membrane proteins, enabling immune evasion. Intracellular bacteria seem to exploit host cell trogocytosis, since they can use it to spread from cell to cell. Thus, a picture is emerging in which trogocytosis plays critical roles in normal physiology, infection, and disease.

The role of trogocytosis in immune surveillance of Hodgkin lymphoma

“… 5 , 6 Their complex interactions within the HL microenvironment have been well summarized and discussed. 5 – 8 This review will focus on the contribution of trogocytosis, 9 , 10 also called transendocytosis, 11 to the establishment of the immunosuppressive microenvironment in HL.…”

“…20 The proteins in the small membrane fragments pinched off from the donor cell are either displayed on the acceptor cell surface or are internalized. 9 , 10 Therefore, trogocytosis helps explaining why certain cell type-specific proteins are present on other cells that do not express them. 21 For example, myelin basic protein-specific T cells, after being activated by allogenic antigen presenting cells (APCs), can present myelin basic protein and conalbumin antigens to other T cells in a second co-culture, indicating the transfer of membrane patches containing specific and irrelevant peptide-MHC class II (pMHCII) from the APC to the T cells.…”

When killers become thieves: trogocytosed PD-1 inhibits NK cells in cancer

“…Rapid cell contact-dependent acquisition of proteins from NK cells to target cells is consistent with trogocytosis, i.e. the acquisition of membrane fragments often performed by immune cells (20). Corroborating this hypothesis, PD-1 transfer was accompanied by acquisition of lipids from tumor cells, as revealed by experiments where NK cells were co-cultured with RMA cells previously labelled with Cell-Vue, a dye that intercalates in the lipid regions of the cellular membrane.…”

Neutrophil interactions with the sexually transmitted parasite Trichomonas vaginalis: implications for immunity and pathogenesis

“…In 2003, the term was again used to describe membrane and protein exchange that occurs during antigen presentation at the immunological synapse from an antigen-presenting cell to a T-cell [76,77], although in this case the trogocytosis did not result in the death of the target cell. Cellular nibbling or gnawing of one cell on an adjacent cell has now been observed across animals and amoebozoas, and during many different biological scenarios such as development, neural remodelling, infection, and mounting and executing immune responses [78]. Importantly, trogocytosis does not always lead to the death of the trogocytosed cell, so it may be helpful to begin to classify trogocytic processes into cytotoxic trogocytosis and non-cytotoxic trogocytosis.…”