Perovskite immunoadjuvant: Remodeling the immunosuppressive microenvironment via photothermal catalysis to enhance T-cell recruitment and amplify the immune response.

Immunotherapeutic efficacy is markedly compromised in "cold" tumors, largely as a consequence of the immunosuppressive milieu within the TME, characterized by hypoxia, a fortified antioxidant defense (e.g., elevated glutathione), and insufficient immunogenicity. This necessitates next-generation strategiy that can remodel the TME and trigger strong anti-tumor immunity. Herein, we engineered an intelligent photothermo-catalytic immunoadjuvant based on polyvinylpyrrolidone (PVP)-modified lanthanum manganite oxide perovskites (La0.93MnO3@PVP, LMOP), which synergizes with photothermal therapy (PTT) to amplify systemic anti-tumor immunity. LMOP demonstrated inherent catalytic activities mimicking both catalase (CAT) and glutathione peroxidase (GPx), which are markedly enhanced under PTT-induced hyperthermia, establishing a thermo-catalytic cascade. This synergy effectively remodeled the TME by generating O2 to alleviate hypoxia and depleting glutathione to disrupt the antioxidant shield. The resulting oxidative stress, coupled with PTT, not only inflicted direct cytotoxicity but also induced mitochondrial damage, thereby triggering a potent immunogenic cell death (ICD) cascade. Remarkably, LMOP-mediated PTT effectively suppressed tumor growth, promoted dendritic cell (DC) maturation and extensive accumulation of CD4+ and CD8+ T cells. This immunoadjuvant design strategy presents a promising paradigm for converting immunosuppressive "cold" tumors into "hot," therapy-responsive phenotypes.