Macrophage depletion restores the DRG microenvironment and prevents axon degeneration in bortezomib-induced neuropathy

Peripheral neuropathy is a common and debilitating side effect of the chemotherapeutic bortezomib (BTZ). To explore the mechanisms underlying BTZ-induced neuropathy (BIPN), we developed a mouse model that replicates the route of administration and approximates the prolonged BTZ exposure experienced by patients. We find that male mice treated with BTZ experience more severe sensorimotor dysfunction and axon loss compared to females and observed similar results when analyzing human data. Using single cell RNA-sequencing, we reveal that BTZ significantly alters the dorsal root ganglia (DRG) microenvironment in mice, producing pronounced sex-specific changes in satellite glial cells (SGCs) in males and females and dysregulation of the extracellular matrix (ECM), particularly in males. These changes are accompanied by expansion of macrophages, which is more pronounced in males. We identify four macrophage subtypes in the DRG, including a pro-fibrotic population that is exclusively associated with BIPN. Depletion of macrophages via anti-CSF1R treatment in male mice prevents BTZ-induced SGC activation and aberrant collagen deposition in DRGs, potently preserves peripheral axons, and improves functional outcomes. These findings highlight SGCs, neuroinflammation and dysregulation of the ECM as drivers of sex-specific differences in BIPN and suggest that targeting neuroinflammation is a promising therapeutic strategy to treat this disease. One Sentence SummaryInflammation and neurofibrosis in DRGs underlie sex-specific differences in bortezomib-induced neuropathy and are promising treatment targets.