Antioxidants & Redox Signaling

Heat stroke causes life-threatening liver injury, but its molecular basis remains poorly understood. We investigated whether ALKBH5-mediated N6-methyladenosine (m⁶A) demethylation stabilizes Hmgb1 transcripts and promotes hepatocyte pyroptosis through the NLRP3 inflammasome. We also developed mesenchymal stem cell membrane-coated glycyrrhizic acid liposomes (MMGLs) as a targeted therapeutic strategy.

RNA-seq of HS rat livers revealed significant enrichment of pyroptosis pathways, with ALKBH5 identified as a hub gene. Mechanistically, heat stress upregulated ALKBH5, which demethylated HMGB1 mRNA, preventing its degradation and enhancing transcript stability. This stabilization led to increased intracellular High-mobility group box 1 (HMGB1) abundance, nucleocytoplasmic translocation, and extracellular release, subsequently activating the NLRP3-Caspase-1-GSDMD axis. Alkbh5 knockdown shortened Hmgb1 half-life and attenuated pyroptosis, whereas HMGB1 supplementation restored it. To target this axis, we engineered MMGLs (encapsulation efficiency: 81.7%), which exhibited superior inflammatory homing compared to unmodified liposomes. In HS rats, MMGLs achieved rapid hepatic accumulation, significantly reduced serum alanine aminotransferase/aspartate aminotransferase, and suppressed Interleukin-1 beta (IL-1β)/IL-18. MMGLs restored redox homeostasis by decreasing reactive oxygen species/malondialdehyde and boosting reduced glutathione/superoxide dismutase, thereby preserving hepatocyte architecture and inhibiting pyroptosis.

This study identifies an epitranscriptomic mechanism in HS-induced liver injury, in which ALKBH5-dependent stabilization of Hmgb1 mRNA amplifies pyroptotic signaling. MMGLs provide a biomimetic nanotherapeutic strategy to interrupt this inflammatory cascade.

ALKBH5-mediated m⁶A demethylation stabilizes HMGB1 to drive hepatocyte pyroptosis during HS. MMGLs effectively target this axis, offering a promising therapeutic approach for acute liver damage. Antioxid. Redox Signal. 45, 173–197.

Cystathionine β-synthase (CBS) is essential for homocysteine (Hcy) transsulfuration, yielding cysteine as a common precursor of hydrogen sulfide (H₂S), glutathione (GSH), and other sulfur molecules, which produce neuroprotective effects in neurological conditions. We previously reported a disruption of microglial CBS/H₂S signaling in a Parkinson’s disease (PD) mouse model. Yet, it remains unclear whether CBS affects nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain-containing 3 (NLRP3) inflammasome activity and other pathologies in PD.

Microglial CBS expression decreased after lipopolysaccharide (LPS) stimulation. Elevated GSSG (the oxidized GSH) content and decreased H₂S generation were found in the brains of microglial cbs conditional-knockout (cbs ^cKO) mice, whereas serum and brain Hcy levels remained unaltered. Moreover, microglial cbs ^cKO mice were susceptible to NLRP3 inflammasome activation and dopaminergic neuron losses caused by LPS injection into the substantia nigra, whereas cbs overexpression or activation produced opposite effects. In vitro studies showed that cbs overexpression or activation suppressed microglial NLRP3 inflammasome activation and interleukin (IL)-1β secretion by reducing mitochondrial reactive oxygen species (mitoROS) level. Conversely, ablation of cbs enhanced NLRP3 expression and mitoROS generation and augmented microglial NLRP3 inflammasome activity in response to adenosine triphosphate challenge, which was blocked by the mitoROS scavenger.

The study demonstrated an elevated GSSG level and reduced H₂S generation, which correlated with a susceptible status of microglia in the brain of cbs ^cKO mice. Our findings reveal a critical role of CBS in restraining the microglial NLRP3 inflammasome by controlling redox homeostasis and highlight that activation or upregulation of CBS may become a potential strategy for PD treatment.

Radioresistance limits the therapeutic efficacy of radiotherapy, and although ferroptosis contributes to radiation-induced tumor suppression, the upstream redox-epitranscriptomic mechanisms remain poorly defined. This study investigated how loss of the antioxidant enzyme glutathione peroxidase 8 (GPX8) influences susceptibility to ionizing radiation (IR), delineated the molecular pathway linking oxidative stress to ferroptosis, and evaluated the potential of GPX8 deletion as a radiosensitization strategy.

We identify GPX8 as a previously unrecognized suppressor of ferroptosis whose deletion markedly amplifies IR-induced ferroptotic cell death. GPX8 deficiency increased reactive oxygen species accumulation, lipid peroxidation, labile iron levels, and ferroptosis-associated gene expression following irradiation. Mechanistic dissection revealed a novel redox-epitranscriptomic axis: oxidative stress induced by GPX8 loss downregulated the transcription factor E2F4, which in turn reduced zinc-finger CCCH-type containing 13 (ZC3H13) expression, leading to N⁶-methyladenine (m⁶A) hypomethylation and stabilization of acyl-CoA synthetase long-chain family member 4 (ACSL4) mRNA. Overexpression of E2F4 or ZC3H13 reversed ACSL4 upregulation, confirming pathway causality. ACSL4 knockdown diminished ferroptosis and rescued the hypersensitivity of GPX8-deficient cells to IR. In an orthotopic xenograft model, GPX8-knockout tumors displayed significantly enhanced radiosensitivity and elevated ferroptotic markers, effects mitigated by the ferroptosis inhibitor liproxstatin-1.

This work uncovers a previously uncharacterized antioxidant–m⁶A–ferroptosis regulatory pathway and provides the first evidence that GPX8 modulates radiotherapy response by epitranscriptomic control of ACSL4 stability via the E2F4–ZC3H13 axis.

GPX8 deletion sensitizes oral cancer to irradiation by promoting ferroptosis through oxidative stress-driven suppression of E2F4 and ZC3H13, resulting in m⁶A hypomethylation and stabilization of ACSL4 mRNA. GPX8 thus represents a promising target for ferroptosis-based radiosensitization. Antioxid. Redox Signal. 45, 219–241.

To investigate the tumor-intrinsic lymphocyte cytosolic protein 2 (LCP2) in esophageal squamous cell carcinoma (ESCA) and its molecular mechanisms in mediating resistance to programmed death-1 (PD-1) therapy.

The expression of LCP2 in ESCA was analyzed using bioinformatics databases and further verified in clinical specimens. Functional studies employed patient-derived organoid models, xenograft models, and molecular assays to assess the impact of LCP2 knockout or overexpression on macrophage polarization, CD8 + T cell exhaustion, and PD-1 therapy response. Mechanistic investigations included nuclear factor-κB (NF-κB) inhibition, signal transducer and activator of transcription 5A (STAT5A) knockdown, chromatin immunoprecipitation, and dual-luciferase reporter assays.

LCP2 was markedly upregulated in ESCA and correlated with advanced stage, lymph node metastasis, and poor survival. Tumor-intrinsic LCP2 expression positively correlated with M2 macrophage polarization and sorted CD8⁺ T cell exhaustion. Mechanistically, this association depended on NF-κB pathway activation in EpCAM⁺ tumor fractions, while STAT5A transcriptionally regulates tumor-intrinsic LCP2 expression as an upstream transcription factor. Knockdown of tumor-intrinsic LCP2 or STAT5A in EpCAM⁺ tumor fractions suppressed the secretion of immunosuppressive cytokines and restored effector T cell function of sorted CD8⁺ T cells. In vivo, LCP2 depletion significantly inhibited tumor growth and synergized with PD-1 blockade. This synergistic effect was characterized by reduced tumor volume and increased CD8⁺ T cell infiltration. Overexpression of LCP2 reversed these effects, confirming its central role in immune escape.

The STAT5A–LCP2–NF-κB axis remodels the immunosuppressive tumor microenvironment to mediate ESCA immune escape and PD-1 resistance. Targeting this regulatory axis provides a novel strategy to overcome immunotherapy resistance in esophageal cancer. Antioxid. Redox Signal. 45, 242–264.

Platelet mitochondria drive platelet activation and thrombosis by fueling energy demands via metabolic reprogramming, regulating calcium-mediated procoagulant signaling, and maintaining functional integrity through quality control mechanisms. Current antiplatelet agents, including P2Y12 antagonists, cyclooxygenase-1 inhibitors, glycoprotein IIb/IIIa blockers, and protease-activated receptor-1 antagonists, effectively prevent thrombosis but increase bleeding risk, underscoring the need for metabolism-targeting strategies.

Here, we summarize key platelet mitochondrial mechanisms driving platelet activation: metabolic reprogramming through oxidative phosphorylation (OXPHOS)-to-glycolysis shifts, calcium flux mediated by the mitochondrial calcium uniporter controlling coagulation, quality control through dynamics and mitophagy, and mitochondrial genome (mtDNA) regulation linked to relevant diseases.

The variable role of OXPHOS in thrombosis remains incompletely understood. Metabolic flexibility complicates therapeutic intervention, while the cytotoxic effects of mitochondrial modulators and technical limitations in the quantification of circulating mtDNA present significant translational challenges.

Development of therapies based on mitochondria-targeted antioxidants and metabolic enzyme modulators is proposed as a promising antiplatelet strategy. Transplantation of platelet-derived mitochondria and standardized detection of mtDNA warrant further exploration for thrombotic diseases. Antioxid. Redox Signal. 45, 265–292.