Lysosomal dysfunction in Schwann cells is involved in bortezomib-induced peripheral neuropathy

摘要

OBJECTIVE The proteasome inhibitor bortezomib(BTZ)is a first-line anti-multi⁃ple myeloma drug.BTZ-induced peripheral neu⁃ropathy(BIPN)is a main adverse effect that char⁃acterized by neuropathic pain.There is still no strategy to prevent or treat BIPN,attributed to the unidentified mechanisms underlying BIPN.Previous studies suggested that BTZ impairs Schwann cells and thus leads to axonal demye⁃lination,whereas it remained not fully understood how BTZ cause Schwann cell death.It was observed that BTZ upregulates the autophagy marker LC3-Ⅱprotein in Schwann cells.However,it remains unclear whether BTZ causes autopha⁃gy-lysosome dysfunction in Schwann cells.METHODS The male C57BL/6 mice were intra⁃venous injection of BTZ(1 mg·kg-1 per day,twice weekly for a total of 4 weeks).The paw withdraw⁃al latency was tested by the Von Frey test and Hargreaves test to reflect the neuropathic pain.The conduction velocity and the action potential amplitude of the tail nerve were tested by neuro⁃physiological assessment to reflect peripheral nerve function.The histomorphology of the sciat⁃ic nerves was detected by immunofluorescence and transmission electron microscopy to reflect the demyelination and axonal degeneration.The RSC96 cells,the Schwann cell-like immortal cells,were cultured and exposed to BTZ.The lysosomal function was determined by Lyso⁃Tracker and DQ-BSA staining.Autophagy-relat⁃ed proteins,including p62 and LC3,and lysosom⁃al hydrolase cathepsin B were determined by Western blotting.RESULTS①BTZ induced mechano-allodynia,neurological conduction abnormalities of the tail nerve,demyelination and axonal degeneration of the sciatic nerves.②BTZ caused lysosomal dysfunction,resulting in the blockade of autophagy flux in Schwann cells and sciatic nerves.③The lysosomal activator Torin1 reversed lysosomal dysfunction caused by BTZ in Schwann cells.④Torin1 improved BTZ-induced mechano-allodynia and demyelination of sciatic nerves.CONCLUSION BTZ led to lyso⁃somal dysfunction in Schwann cells and contrib⁃uted to BIPN.Lysosomal activation could be a promising strategy for BIPN intervention.