Lacagnina, M. J. | Search bioRxiv

bioRxiv2026

DRG meningeal tertiary lymphoid structures are regulated by B cells as a pronociceptive locus after peripheral nerve injury

B cell-derived IgG in the dorsal root ganglia (DRG) drives neuropathic pain after peripheral nerve injury (PNI), but the site of B cell organization is unclear. Here, PNI induced leukocyte clusters in the DRG meninges, enveloped by lymphatic endothelium and apposed to high endothelial venules. These clusters resemble tertiary lymphoid structures (TLSs) with germinal center-like features, including germinal center B cells and plasma cells, and follicular dendritic and follicular helper T cells. Single-cell RNA sequencing revealed enrichment of germinal center B cells in the DRG meninges after PNI. Germinal center B cells regulate TLS organization: TLSs were absent after deletion of Ezh2 from germinal center-experienced B cells. Intrathecal CD20 monoclonal antibody to locally deplete B cells also disrupted TLS organization. Conversely, intrathecal B cell transfer to B cell-deficient (muMT) mice was sufficient for TLS organization after PNI. Allodynia did not develop when TLS organization was disordered. Similar TLSs formed in pig DRG after tail docking and in human donors with chronic pain, where B cell receptor clonotype analysis confirmed functional maturity. Together, these data establish that germinal center B cells are required for TLS organization, and that disrupting this process abolishes the development of neuropathic pain after PNI.

neuroscience↗

bioRxiv2021

Preconditioning by voluntary wheel running attenuates later neuropathic pain via Nrf2 antioxidant signaling in rats

Animal and human studies have shown that exercise prior to nerve injury prevents later chronic pain, but the mechanisms of such preconditioning remain elusive. Given that exercise acutely increases formation of free radicals, triggering antioxidant compensation, we hypothesized that voluntary running preconditioning would attenuate neuropathic pain by supporting redox homeostasis after sciatic nerve injury in male and female rats. We show that 6 weeks of voluntary wheel running suppresses neuropathic pain development induced by chronic constriction injury (CCI) across both sexes. This protection was associated with reduced nitrotyrosine immunoreactivity--a marker for peroxynitrite--at the sciatic nerve injury site. Our data suggest that prior voluntary wheel running does not reduce production of peroxynitrite precursors, as expression levels of inducible nitric oxide synthase and NADPH oxidase 2 were unchanged. Instead, voluntary wheel running increased superoxide scavenging by elevating expression of superoxide dismutases 1 and 2. Prevention of neuropathic pain was further associated with activation of the master transcriptional regulator of the antioxidant response, nuclear factor E2-related factor 2 (Nrf2). Six weeks of prior voluntary wheel running increased Nrf2 nuclear translocation at the sciatic nerve injury site; in contrast, 3 weeks of prior wheel running, which failed to prevent neuropathic pain, had no effect on Nrf2 nuclear translocation. The protective effects of prior voluntary wheel running were mediated by Nrf2, as suppression was abolished across both sexes when Nrf2 activation was blocked during the running phase. This study provides insight into the mechanisms by which physical activity may prevent neuropathic pain.

neuroscience↗