Distinct iNKT Cell Populations Use IFNγ or ER Stress-Induced IL-10 to Control Adipose Tissue Homeostasis
FLIVO® (FLuorescence in vIVO) is a powerful method for assessing caspase activity in vivo. FAM-FLIVO poly caspase probes are non-cytotoxic, cell-permeant fluorescent inhibitors of caspases optimized for use in whole live animals. ICT’s FAM-FLIVO® poly caspase inhibitor probe contains the preferred binding sequence for most caspases (Val-Ala-Asp or VAD). This preferred poly caspase tripeptide binding sequence is labeled with a carboxyfluorescein (FAM) dye and a fluoromethyl ketone (FMK) reactive entity. In this study on iNKT cells, FAM-FLIVO was used to confirm apoptosis.
IL-10 production and metabolic homeostatic control are characteristics that phenotypically distinguish adipose tissue invariant natural killer T (iNKT) cells from other iNKT cell types. In this publication, researchers used single-cell RNA sequencing to identify two populations of adipose iNKT cells according to expression of cell surface protein NK1.1. In response to adipose tissue lipids, NK1.1NEG cells primarily produced IL-10 and other anti-inflammatory cytokines, while NK1.1POS iNKT cells largely produced IFNγ, which is typically considered pro-inflammatory. Interestingly, in lean adipose tissue, IFNγ production in NK1.1POS iNKT cells plays a paradoxical role, driving NK-mediated killing of proinflammatory macrophages, thereby suppressing inflammation.
Reference: LaMarche et al., 2020, Cell Metabolism 32, 243-258