Propagation of senescent phenotypes by extracellular HMGB1 is dependent on its redox state

Background & purpose: Cellular senescence spreads systemically through blood circulation, but its mechanisms remain unclear. High mobility group box 1 (HMGB1), a multifunctional senescence-associated secretory phenotype (SASP) factor, exists in various redox states. Here, we investigate the role of redox-sensitive HMGB1 (ReHMGB1) in driving paracrine and systemic senescence.

Methods: We applied the paracrine senescence cultured model to evaluate the effect of ReHMGB1 on cellular senescence. Each redox state of HMGB1 was treated extracellularly to assess systemic senescence both in vitro and in vivo. Senescence was determined by SA-β-gal & EdU staining, p16^INK4a and p21 expression, RT-qPCR, and Western blot methods. Bulk RNA Sequencing was performed to investigate ReHMGB1-driven transcriptional changes and underlying pathways. Cytokine arrays characterized SASP profiles from ReHMGB1-treated cells. In vivo, young mice were administered ReHMGB1 systemically to induce senescence across multiple tissues. A muscle injury model in middle-aged mice was used to assess the therapeutic efficacy of HMGB1 blockade.

Results: Extracellular ReHMGB1, but not its oxidized form, robustly induced senescence-like phenotypes across multiple cell types and tissues. Transcriptomic analysis revealed activation of RAGE-mediated JAK/STAT and NF-κB pathways, driving SASP expression and cell cycle arrest. Cytokine profiling confirmed paracrine senescence features induced by ReHMGB1. ReHMGB1 administration elevated senescence markers in vivo, while HMGB1 inhibition reduced senescence, attenuated systemic inflammation, and enhanced muscle regeneration.

Conclusion: ReHMGB1 is a redox-dependent pro-geronic factor driving systemic senescence. Targeting extracellular HMGB1 may offer therapeutic potential for preventing aging-related pathologies.

Cellular senescence; Extracellular HMGB1; Paracrine senescence; Redox; SASP.