MM-derived exosomes can promote apoptosis and inhibit proliferation of HD-CD4⁺T, inhibit apoptosis and promote proliferation but inhibit perforin secretion of HD-CD8⁺T, inhibit apoptosis and promote proliferation HD-Treg, and promotes IL-10 secretion

OBJECTIVE: To study the effects of multiple myeloma (MM)-derived exosomes on the number and function of CD4⁺T, CD8⁺T and regulatory T cells in healthy donors (HD) and MM patients.

METHODS: MM cell-derived (OPM2, U266) exosomes were extracted by ultracentrifugation and kit method and co-cultured with CD4⁺T, CD8⁺T and CD4⁺CD25⁺CD127dimT cells (Treg) from HD and MM patients sorted by magnetic beads. Flow cytometry was used to detect the apoptosis rate of T cells, level of perforin and granzyme B in CD8⁺T. Cell viability was detected by CCK8 kit, and IL-10 and TGF-β levels were detected by ELISA.

RESULTS: HD-CD4+T apoptotic rate was higher in the OPM2 group (6.24±1.24%) and U266 group (5.42±1.07%) than in the control group (4.37±0.96%). The HD-CD4+T viability in U266 group (85.45±6.09%) decreased compared with the control group. The apoptotic rate of HD-CD8+T was decreased in the OPM2 group (9.97±1.28%) and the U266 group (11.00±1.75%) compared with the control group (16.12±2.95%). HD-CD8+T cell viability was increased in the OPM2 group (112.63±3.88%) and the U266 group (111.70±3.62%) compared with the control group. Perforin of HD-CD8+T in U266 group (9.34±2.36%) was lower than the control group (12.76±3.31%); Perforin of MM-CD8+T in OPM2 group (6.48±1.06%) and U266 group (5.63±1.15%) decreased compared with the control group (10.55 ± 2.50%). The apoptosis rate of HD-Treg was lower in OPM2 group (15.33±3.87%) and U266 group (11.71±2.71%) than in control group (19.61±3.50%). The apoptosis rate of MM-Treg was higher in U266 group (37.29±6.54%) than the control group (29.95 ± 6.68%). The viability of HD-Treg in U266 group (173.48±34.99%) was higher than the control group. The viability of MM-Treg in OPM2 group (82.29±12.16%) was lower than the control group. The supernatant IL-10 from HD-Treg in OPM2 group (18.53±8.08 pg/ml) was higher than the control group (8.49±4.02 pg/ml). The supernatant TGF-βfrom MM-Treg was decreased in the OPM2 group (290.29±23.21pg/ml) and the U266 group (230.03±15.96pg/ml) compared with the control group (387.49±21.60pg/ml) (P<0.05).

Conclusion: MM-derived exosomes can promote apoptosis and inhibit proliferation of HD-CD4⁺T, inhibit apoptosis and promote proliferation but inhibit perforin secretion of HD-CD8⁺T, inhibit apoptosis and promote proliferation HD-Treg, and promotes IL-10 secretion.