Targeting HMGB1 for Renal Ischemia and Reperfusion Injury: Mechanisms and Therapeutic Strategies.

Although the underlying mechanisms of renal IRI have been extensively studied, the corresponding effective treatments are still lacking. HMGB1, an important nuclear factor that is secreted outside cells when experiencing stress conditions, acts as a DAMP and exerts crucial effects on renal IRI. Many studies have suggested that the effect of HMGB1 on kidney damage is mediated mainly through the interaction of HMGB1 with pattern recognition receptors such as TLR4 and RAGE, which then results in the aggravation of local inflammatory response, increased infiltration of leukocytes, and finally renal tubular damage. Preclinical studies using animal models have demonstrated that inhibition of HMGB1 and downstream signal pathways can attenuate renal injury. This review critically evaluates HMGB1 in renal IRI across redox state, subcellular localization, temporal and cell-specific release, receptor usage, integrated stress pathways, autophagy, and regulated cell death. It also compares direct neutralization, inhibition of release or translocation, epigenetic/RNA-based regulation, and receptor-directed strategies. The evidence is predominantly derived from short-term rodent studies, with one large-animal antibody study and no therapeutic human trials. Accordingly, HMGB1 is best regarded as a biologically compelling but clinically unvalidated target whose therapeutic value will depend on redox- and phase-selective inhibition, kidney-directed delivery, and rigorous pharmacokinetic and safety evaluation.