Involvement Of CXCL10 In Neuronal Damage Under The Condition Of Spinal Cord Injury And The Neuroprotective Effect Of Nrg1

Background: Spinal cord injury(SCI)refers to the temporary or permanent loss of spinal cord function caused by trauma(such as car accidents,falls,and sports-related injuries)or nontrauma(such as tumors,infections,or degenerative diseases of the intervertebral disc).It is crucial to clarify the pathogenesis of secondary injury and complications of SCI and develop effective treatments.Elevated C-X-C motif chemokine ligand 10(CXCL10)levels can be detected in the spinal cord,cerebrospinal fluid,and peripheral blood after SCI.Most of the existing studies on CXCL10 have focused on post-SCI neuropathic pain.One research has shown that CXCL10 induces cell apoptosis in human fetal neurons and human NT2 neurons.Antagonizing CXCL10 with an antibody targeting CXCL10 can inhibit immune response and tissue loss after SCI in vivo.But the role of CXCL10 in neuronal damage under SCI pathologic conditions needs further study.These results suggest that CXCL10 may be involved in neuronal injury through modulation of immune response and direct action on neuronal cells,causing apoptosis.And there are fewer studies related to the involvement of CXCL10 in neuronal injury through regulating glial cells.Therefore,this study has certain innovation.Neuregulin 1(Nrg1)levels are downregulated after SCI.The existing evidence suggests that Nrg1 plays a role in neuronal protection after SCI.There is still a large gap in research on the role of Nrg1 in CNS injury and regeneration in adult mammals.Therefore,Nrg1 has certain development potential as a neuroprotective agent for treating neuronal injury after SCI.Objective: This study aims to elucidate the role of CXCL10 in neuronal damage after SCI.Under SCI pathological conditions,CXCL10 may be involved in neuronal injury through modulation of immune response and direct action on neuronal cells,causing apoptosis.We use Nrg1 as a therapeutic drug to demonstrate that Nrg1 may exert a neuroprotective effect by activating the Erb B4 receptor signaling pathway and inhibiting CXCL10-induced neuronal damage in SCI.Method: In this study,we first analyzed the GEO database to identify the expression levels of Cxcl10 and Nrg1 in different age groups of SCI mice or at different time points after SCI.Then,we investigated the expression changes of CXCL10 after SCI in vivo and explored the expression changes of CXCR3 in neurons,microglia,and astrocytes.Next,we studied the direct effects of CXCL10 and Nrg1 on the HT22 and NSC34 cell lines in vitro using a cell scratch model.Finally,we studied whether CXCL10 can promote the activation of BV2 microglia and MA astrocytes in vitro,leading to neuronal damage and inhibiting the healing of the scratchwound model.The neuroprotective effect of Nrg1 in promoting the healing of the scratchwound model by activating the Erb B4 receptor signaling pathway was also studied.Results: Through bioinformatics analysis,we found that the levels of Cxcl10 is increased,and Nrg1 is decreased at 1,3,and 7 days after SCI,as well as in young and aged SCI mice.In SCI mice at 8 weeks post injury,we found that inflammation was intensified in the spinal cord,with high expression of CXCL10 and CXCR3.The expression of CXCR3 in neurons,astrocytes,and microglia were significantly enhanced in the injured spinal cord.In the scratch-wound model of HT22 cells and NSC34 cells,CXCL10 could induce apoptosis of HT22 cells and NSC34 cells but was insufficient to inhibit the healing of both cell types after scratch injury.Nrg1 could protect neurons by partially antagonizing the neurotoxic effects of CXCL10 and promote scratch healing by antagonizing the inhibitory effects of CXCL10 on neurite outgrowth.Finally,we found that when CXCL10 acted on BV2 microglia and MA astrocytes with or without LPS pre-treatment,the secretions(containing TNF-α and IL-1β or IFN-γ)of BV2 and MA cells could inhibit the scratch healing of HT22 and NSC34 cells.Nrg1 can partially alleviate these inhibitory effects through the p Erb B4 / p STAT5 or p Erb B4 / p Erk1/2 pathway.Nrg1 also antagonized the pro-apoptotic effects of BV2 and MA cell secretions and promoted scratched wound healing.Conclusion: Considering all those results,we can conclude that CXCL10 primarily activates BV2 microglia and MA astrocytes to secrete neurotoxic substances rather than directly acting on neurons to inhibit healing in vitro scratch-wound model of SCI.Nrg1 can protect neurons by ameliorating the apoptosis-promoting effects of CXCL10.It may also function by inhibiting the proapoptotic and anti-proliferative effects of CXCL-10-stimulated BV2 and MA cell secretions.These beneficial effects of Nrg1 may be partially mediated by the p Erb B4/p Erk1/2 or p Erb B4/pSTAT5 pathway,thus playing a role in neuronal protection.