Neuroinflammation is a crucial process for the loss of retinal ganglion cells (RGC), a major characteristic of glaucoma. High expression of high mobility group box protein 1 (HMGB1) plays a detrimental role in inflammatory processes and is elevated in the retinas of glaucoma patients. Therefore, this study aimed to investigate the effects of intravitreal injection of an anti-HMGB1 monoclonal antibody (anti-HMGB1 Ab) in an experimental animal model of glaucoma. Two groups of Spraque Dawley rats received episcleral vein occlusion to chronically elevate intraocular pressure (IOP): (1) IgG group, intravitreal injection of an unspecific IgG as a control, n=5, (2) HMGB1 group, intravitreal injection of an anti-HMGB1 Ab, n=6. IOP, retinal nerve fiber layer thickness (RNFLT), and the retinal flash response was monitored longitudinally. Post-mortem examinations included immunohistochemistry, microarray, and mass spectrometric analysis. RNFLT was significantly increased in the HMGB1 group compared to the IgG group (p<0.001). RGC density showed improved neuronal cell survival in the retina in HMGB1 compared to the IgG group (p<0.01). Mass spectrometric proteomic analysis of retinal tissue showed increased abundance of RNA metabolism-associated heterogeneous nuclear ribonucleoproteins (hnRNPs), such as hnRNP U, D, and H2, in animals injected with the anti-HMGB1 Ab, indicating that application of the antibody may cause increased gene expression. Microarray analysis showed significantly decreased expression of C-X-C motif chemokine ligand 8 (CXCL8, p<0.05) and connective tissue growth factor (CTGF, p<0.01) in the HMGB1 group. Thus, these data suggest that intravitreal injection of anti-HMGB1 Ab reduced HMGB1-dependent inflammatory signaling and mediated RGC neuroprotection.