Immunomodulation by 4-Hydroxy-TEMPO (TEMPOL) and Dimethyl Fumarate (DMF) After Ventral Root Crush (VRC) in C57BL/6J Mice: A Flow Cytometry Analysis

Spinal motor nerve root lesions can happen after avulsion or crush, generating acute motoneuron death and synaptic loss, consequently, causing motor and sensory dysfunctions. Local response is mediated by astroglial and microglial cells, giving rise to a pro-inflammatory profile. TEMPOL and DMF are drugs that have been studied in our laboratory after spinal cord nerve root injuries and have demonstrated significant results in terms of neuroprotection and immunomodulation, decreasing the inflammation process. In the present work, a flow cytometry approach was used to evaluate cellular responses to injury and immunomodulation. For this, injured animals received TEMPOL, DMF or vehicle once a day for 7, 14 or 28 days of treatment. Flow cytometry multiparametric analysis allowed the quantification of different pro- and anti-inflammatory glial, macrophage and lymphocyte markers. Contrasting with the vehicle treated counterpart, TEMPOL and DMF led to downregulation of pro-inflammatory cytokines in astrocytes and microglia subpopulations, but did not show significant results in increasing anti-inflammatory phenotypes. As for macrophage and lymphocyte subpopulations, both treatments showed a balance between pro- and anti-inflammatory phenotypes. Therefore, it was concluded that both drugs exhibit immunomodulatory action, contributing to a pro-regenerative profile in the tissue.