Fucoidan reduces NETs accumulation and alleviates chemotherapy-induced peripheral neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is a serious adverse reaction of chemotherapy with limited treatment. Previous research indicates neutrophil extracellular traps (NETs) is a critical pathogenesis of CIPN. LPS/HMGB1 serve as important inducers of NETs. Here, we aim to target inhibiting NETs formation (NETosis) to alleviate CIPN. Clinically we found the content of LPS, HMGB1 and NETs in the plasma of CIPN patients was significantly increased and positively correlated with VAS scores. Fucoidan decreased LPS/HMGB1/NETs content and relieved CIPN in mice. Mechanistically, fucoidan upregulated the scavenger receptor A1 (SR-A1) expression and promoted bone marrow derived macrophage (BMDM) to phagocytize LPS/HMGB1. Fucoidan also facilitated BMDM to engulf NETs via the recognition and localization of SR-A1 and HMGB1. The therapeutic effects of fucoidan were abolished by SR-A1 knockout. RNA-seq analysis showed that fucoidan significantly increased sqstm1 (p62) gene expression. Fucoidan promoted the competitive binding of sqstm1 and Nrf2 to Keap1, increasing Nrf2 nuclear translocation and SR-A1 transcription. Additionally, microbial diversity sequencing analysis (16S) showed that fucoidan increased gut microbiota diversity and abundance, and upregulated the Bacteroides/Firmicutes ratio. In conclusion, fucoidan promotes SR-A1-mediated phagocytosis of LPS/HMGB1/NETs and maintains gut microbial homeostasis, providing a potential therapeutic strategy for CIPN. The BMDM were extracted by isolating the tibia and femurs of the mice after their necks were removed. The cells within the tibia and femurs were blown into DMEM medium (10% FBS+10% L929 culture medium +1% penicillin-streptomycin solution,100×) . After they were cultured for 7 days, trypsin was used to digest them followed by centrifugation, suspension, and seeding onto petri dishes. Fucoidan (250ug/ml) was administered prior to treating with L-OHP (5uM) for 12 hours. Total cellular RNA was extracted using Trizol for high-throughput sequencing.