Mast cell intracellular traps (MIT) release neutrophil effector proteins during degranulation and nexocytosis

ABSTRACT: Degranulating mast cells (MCs) release inflammatory mediators (proteins, lipids, small molecules), including chemokines and chemoattractants, which recruit other immune cells in tissues. Neutrophils can initiate self-amplifying swarming responses via intercellular communication through the lipid leukotriene B4 (LTB4). Initially discovered by two-photon intravital microscopy in mice and confocal live cell imaging, we show that degranulating MCs release LTB4 and exploit this attractant by re-directing neutrophils to MCs. In a process generally termed entosis, neutrophil cluster formation around MCs results in the trapping of living neutrophils inside MC vacuoles in vivo and in vitro. Thus, we identify a novel cell-in-cell structure between MCs and neutrophils, which we term “Mast Cell Intracellular Trap” (MIT). Compared to MCs, MITs revealed improved MC metabolism and recovery after degranulation. This leads to several benefits for MITs: (1) they can be more efficiently re-stimulated than MCs, (2) they show improved survival under nutrient limitation, and (3) MITs store neutrophil proteins, DNA and effector molecules, which can be released after re-stimulation. In this context, we compare the secretome (secreted proteins) of MCs and MITs (in cell culture) before and subsequent to degranulation via label-free nanoLC-MS. In summary, mast cells trap and cannibalize swarming neutrophils, which supply nutrients, proteins and inflammatory molecules to recovering MCs. Our studies may have potential implications for chronically activated MCs in MC-related immune disorders.

INSTRUMENT(S): Orbitrap Exploris 480

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Primary Cell, Mast Cell, Cell Culture, Neutrophil

SUBMITTER: Gerhard Mittler  

LAB HEAD: Gerhard Mittler

PROVIDER: PXD044140 | Pride | 2024-06-18

REPOSITORIES: Pride