HMGB1 and HMGB2 Effects on Programmed Cell Death Ligand 1 With the Receptor for Advanced Glycation-End Product Pathway in the Monocyte Cells of Patients With Multiple Sclerosis

Background: High-mobility group box 1 (HMGB1) is a nonhistone, DNA-binding protein that serves a crucial role in regulating gene transcription and is involved in various proinflammatory, extracellular activities. The aim of this study was to explore whether HMGB1 stimulation can upregulate the expression of programmed cell death ligand 1 (PD-L1). Methods: Thirty multiple sclerosis (MS) patients at mild, moderate, and severe stages were recruited from the MS clinic. Blood samples were collected from patients, and monocyte cells were isolated from peripheral blood mononuclear cells (PBMCs) using magnetic-activated cell sorting brush separation. The isolated monocytes were cultured and stimulated with HMGB1 and HMGB2 over a time course of 0 hour, 6 hours, 12 hours, 24 hours, and 48 hours. Results: The effects of HMGB1 and HMGB2 stimulation were evaluated over time. PD-L1 expression increased significantly throughout the time course, with peak increases observed for HMGB1 and HMGB2 24 and 12 hours after stimulation, respectively. Conclusion: Evidence from the present study suggests that enhanced PD-L1 expression may result from HMGB1 and HMGB2 stimulation in MS patients.