Journal: Journal of Extracellular Vesicles
Article Title: Neutrophils Promote Metabolic Dysfunction‐Associated Steatotic Liver Disease Through Extracellular Vesicle‐mediated Lipid Transfer
doi: 10.1002/jev2.70350
Figure Lengend Snippet: Neutrophils develop a lipid‐laden state through free fatty acid uptake. (A–C) Neutrophils uptake free fatty acids (FAs). Human neutrophils were exposed to free fatty acids (PA, palmitic acid, 50 µM; OA, oleic acid, 50 µM; LA, linoleic acid, 50 µM). Lipid droplets (LDs) were visualized by BODIPY staining and immunofluorescence microscopy. SSO, sulfo‐ N ‐succinimidyl esters (CD36 inhibitor, 100 µM); Lipo, lipofermata (FATP2 inhibitor, 5 µM). (A) Schematic illustration of free FAs uptake by neutrophils. Representative immunofluorescence images (B) and quantification of LDs (C) in neutrophils exposed to free FAs. (D–F) Neutrophils acquire lipids from adipocytes. Mouse neutrophils were co‐cultured with differentiated 3T3‐L1 (d3T3‐L1) in the presence of TNF‐α, and LDs within the neutrophils were examined using immunofluorescence microscopy. (D) Schematic illustration of adipocyte‐to‐neutrophil lipid transfer. (E) Representative immunofluorescence images of neutrophils co‐cultured with adipocytes. Adipocytes are delineated by dashed lines, and neutrophils surrounding the adipocytes are indicated by arrowheads. (F) Quantification of LDs in neutrophils co‐cultured with adipocytes. Neutrophils co‐cultured with adipocytes were harvested, and intracellular LDs were measured using BODIPY staining. (G and H) Metabolic pathways in lipid‐laden neutrophils. (G) qPCR analysis of lipid metabolism‐related genes in vehicle‐ and OA‐treated neutrophils. (H) Heatmap showing the relative mRNA expression levels in OA‐treated neutrophils compared with the vehicle‐treated neutrophils. (I) Intracellular concentrations of FAs and TGs in OA‐treated neutrophils. (J–M) Lipidomics analysis in neutrophils exposed to OA. (J) Principal component analysis of glycerolipids in neutrophils. (K) Differential metabolite analysis in OA‐treated neutrophils. Scatter plot showing the log2 fold change of metabolites between OA‐ and vehicle‐treated neutrophils, with upregulated DG and TG species marked. (L and M) Heatmap showing the relative expression levels of selected DG and TG species enriched in OA‐treated neutrophils. Each heatmap annotates lipid species and their fatty acid composition. ABHD5, Abhydrolase domain containing 5; ACAA2, Acetyl‐CoA acyltransferase; ACACA, Acetyl‐CoA carboxylase alpha; ACAT, Acetyl‐CoA: cholesterol acyltransferase; ACLY, ATP citrate lyase; AGPAT, 1‐acylglycerol‐3‐phosphate O‐acyltransferase; ACSL, Acyl‐CoA synthetase long‐chain family member; CD36, Cluster of differentiation 36; CPT, Carnitine palmitoyltransferase; DGAT, (Diacylglycerol O‐acyltransferase); FABP, Fatty acid‐binding protein; FASN, Fatty acid synthase; G0S2, G0/G1 switch gene 2; HADHA, Hydroxyacyl‐CoA dehydrogenase / 3‐ketoacyl‐CoA thiolase / enoyl‐CoA hydratase alpha subunit; HILPDA, Hypoxia‐inducible lipid droplet‐associated protein; LIPE, Lipase E; MGAT, Mannosyl‐glycoprotein beta‐1,2‐N‐acetylglucosaminyltransferase; MGLL, Monoglyceride lipase; PLIN, Perilipin; PNPLA, Patatin‐like phospholipase domain containing; SLC27A4, Solute carrier family 27 member 4. All results are expressed as mean ± SEM. * p < .05; ** p < .01; *** p < .001.
Article Snippet: To examine the functional contribution of EV biogenesis and uptake to neutrophil‐mediated lipid transfer HepG2 cells (1 × 10 6 cells) were co‐cultured with lipid‐laden neutrophils (1 × 10 7 cells) for 2 h in the presence of ROCK inhibitor Y‐27632 (50 μM, MedChemExpress, #HY‐10071) to suppress EV formation, or cytochalasin D (50 μg/mL) to inhibit EV uptake.
Techniques: Staining, Immunofluorescence, Microscopy, Cell Culture, Expressing, Binding Assay