Fig. 6
Proteins in M2-EVs were the key components in protecting tight junction structure and barrier integrity from disruption in Caco-2 cells. A GSEA showed that M2-EV proteins were highly related to M2 protein signature. B GSEA suggested high enrichment of M2-EV proteins in ECM structural constituent. C Heatmap showing the relative abundance of representative ECM constituents and enzymes in signature proteins of M2-EVs, compared to those of M1-EVs. D Representative images of occludin IF of Caco-2 cells and quantification of occludin signal intensity. The differentiated Caco-2 monolayers were treated with PBS or regular or heated M2-EVs in PBS (6 × 109/mL) for 48 h in the presence of 1% DSS. E M2-EVs prevented DSS-induced TEER reduction, but heated M2-EVs lost such protective effects. The differentiated Caco-2 monolayers were pretreated with PBS or regular or heated M2-EVs in PBS (6 × 109/mL) for 36 h, followed by treatment with 1.5% DSS for 48 h. F Representative images of occludin IF of Caco-2 cells and quantification of occludin signal intensity. The differentiated Caco-2 cells were treated with PBS, M2-EVs in PBS (6 × 109/mL), FMOD (3 µg/mL), MFGE8 (3 µg/mL), or FMOD (1.5 µg/mL) and MFGE8 (1.5 µg/mL) together for 48 h in the presence of 1% DSS. G FMOD and MFGE8 proteins protected cells from DSS-induced TEER reduction. The differentiated Caco-2 monolayers were pretreated with PBS, M2-EVs in PBS (6 × 109/mL), FMOD (3 µg/mL), MFGE8 (3 µg/mL), or FMOD (1.5 µg/mL) and MFGE8 (1.5 µg/mL) together for 36 h, followed by treatment with 1.5% DSS for 48 h. *P < 0.05 and **P < 0.01 relative to cells treated with DSS alone (black bar)