Hmox1 is Identified as a Ferroptosis Hub Gene and Associated with the M1 Type Microglia/Macrophage Polarization in Spinal Cord Injury: Bioinformatics and Experimental Validation

Ferroptosis and immune cell infiltration are important pathological events in spinal cord injury (SCI), but links between ferroptosis and immune microenvironment after SCI were rare reported. In our study, 77 FRDEGs were screened at 7 days after SCI. GO analysis of FRDEGs showed that aging (GO:0007568; P-value = 1.11E-05) was the most remarkable enriched for biological process, protein binding (GO:0005515; adjusted P-value = 4.44E-06) was the most significantly enriched for molecular function, cytosol (GO:0005829; adjusted P-value = 1.51E-04) was the most prominent enriched for cellular component. Meanwhile, Ferroptosis was significantly enriched both in KEGG (rno04216; adjusted P-value = 0.001) and GSEA (NES = 1.35; adjusted P-value = 0.004) analysis. Next, Hmox1 (Log(2)Fold change = 6.52; adjusted P-value = 0.004) was identified as one of hub genes in SCI-induced ferroptosis. In the results of immune cell infiltration analysis, proportion of microglia/macrophage was significantly increased after SCI, and Hmox1 was found to positively correlate to the M1 type microglia/macrophage abundance. Finally, effects of Hmox1 on ferroptosis and M1 type polarization were validated in vivo and in vitro. Summarily, we found that Hmox1 was the hub gene in SCI-induced ferroptosis and associated with the M1 type polarization.