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BackgroundInterleukin (IL) 1 released from monocytes/macrophages is one of the critical determinants in mediating the adverse events of chimeric antigen receptor T cell (CAR-T) therapy, including cytokine release syndrome and neurotoxicity. However, the molecular mechanisms of IL-1 production during CAR-T therapy remain unknown.MethodsThe roles of AIM2 and α1-adrenergic receptor (α1-AR) in CAR-T treatment-induced IL-1β release were evaluated by gene silencing, agonist or antagonist treatment. The phenotype switch of macrophages in response to CAR-T treatment was analyzed concerning cytotoxicity of CAR-T cells and proliferation of activated T cells.ResultsThis study provided the experimental evidence that CAR-T treatment-induced activation of AIM2 inflammasome of macrophages resulted in the release of bioactive IL-1β. CAR-T treatment-induced α1-AR-mediated adrenergic signaling augmented the priming of AIM2 inflammasome by enhancing IL-1β mRNA and AIM2 expression. Meanwhile, tumor cell DNA release triggered by CAR-T treatment potentiated the activation of AIM2 inflammasome in macrophages. Interestingly, an apparent phenotypic switch in macrophages occurred after interacting with CAR-T/tumor cells, which greatly inhibited the cytotoxicity of CAR-T cells and proliferation of activated T cells through upregulation of programmed cell death-ligand 1 (PD-L1) and indoleamine 2,3-dioxygenase (IDO) in the macrophages. Blockade of AIM2 inflammasome or α1-AR reversed the upregulation of PD-L1 and IDO and the phenotypic switch of the macrophages.ConclusionOur study implicates that CAR-T therapy combined with the blockade of AIM2 inflammasome or α1-AR may relieve IL-1β-related toxic side effects of CAR-T therapy and ensure antitumor effects of the treatment.

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Pulmonary microvascular leakage is one of the characteristics of blood-air barrier dysfunction in septic acute lung injury/acute respiratory distress syndrome (ALI/ARDS). Fibroblast growth factor-inducible 14 (Fn14) exerts diverse functions under certain circumstances. However, the role of Fn14 on the integrity of pulmonary microvascular endothelial cells (PMVECs) during sepsis remains unknown. Septic ALI was induced via cecal ligation and puncture (CLP). Fn14 expression on PMVECs was measured 24 h after surgery. The effects of Fn14 blockade on septic ALI were investigated in vivo and in vitro. Compared with the Sham group, Fn14 expressed in septic PMVECs was increased significantly 24 h after surgery. The protein level in bronchoalveolar lavage fluid, the lung wet to dry ratio, and neutrophil/macrophage infiltration in lungs were reduced in septic mice after Fn14 blockade. Similarly, ICAM-1 and MCP-1 levels were attenuated after Fn14 blockade or knockdown in lungs or human pulmonary microvascular endothelial cells (HPMECs). Furthermore, Fn14 silencing reduced Caspase-3 levels and upregulated the transendothelial electrical resistance level in TNF-like weak inducer of apoptosis-treated HPMECs. In addition, the degree of lung fibrosis was ameliorated and the survival of CLP mice was improved significantly after Fn14 blockade. In conclusion, Fn14 on PMVECs plays an important role in the progress of septic ALI. Fn14 blockade may prove to be an innovative lung-protective strategy for the treatment of septic ALI.

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