ABSTRACT
IL-33 is a danger signal that binds to its receptor ST2L to promote tumor progression. This study identifies the IL-33/ST2L positive-feedback loop and the trafficking of ST2L membrane presentation in macrophages that contribute to lung tumor progression. Mechanistically, IL-33 induces ST2L upregulation by activating NF-κB, which binds to the promoter region of the ST2L gene. Moreover, Rab37, a small GTPase involved in membrane trafficking, mediates ST2L trafficking to the plasma membrane of M2 macrophages. This IL-33/NF-κB/ST2L/Rab37 axis promotes positive-feedback loops that enhance ST2L expression and membrane trafficking in M2 macrophages. Notably, neutralizing antibodies against IL-33 or ST2L block NF-κB activity, suppress M2 macrophage polarization, and synergistically inhibit tumor growth when combined with cisplatin treatment in vitro/vivo. Clinically, Rab37+/ST2L+/CD206+ tumor-infiltrating M2 macrophages correlate with advanced-stage lung cancer patients with poor response to chemotherapy. These findings unveil a positive-feedback mechanism and provide a basis for IL-33/ST2L-targeting therapy for cancer.
Subject(s)
Interleukin-33 , Lung Neoplasms , Macrophages , NF-kappa B , rab GTP-Binding Proteins , Interleukin-33/metabolism , Interleukin-33/genetics , Humans , Lung Neoplasms/pathology , Lung Neoplasms/drug therapy , Lung Neoplasms/metabolism , Lung Neoplasms/genetics , NF-kappa B/metabolism , Macrophages/metabolism , Macrophages/drug effects , Animals , rab GTP-Binding Proteins/metabolism , rab GTP-Binding Proteins/genetics , Mice , Feedback, Physiological , Cell Line, Tumor , Signal Transduction/drug effects , Mice, Inbred C57BL , FemaleABSTRACT
BACKGROUND: Traumatic Spinal Cord Injury (SCI) is a severe condition usually accompanied by an inflammatory process that gives rise to uncontrolled local apoptosis and a subsequent unfavorable prognosis. One reason for this unfavorable outcome could be the activation of the NLRP3 inflammasome. OBJECTIVE: MCC950 is a specific inhibitor of NLRP3 that further inhibits the formation of the NLRP3 inflammasome. The purpose of this study was to determine whether the NLRP3 inflammasome was associated with the severity of local apoptosis and whether MCC950 could prevent neuronal apoptosis following SCI. METHODS: In this study, primary cortical neurons were cultured in vitro. With or without pretreatment/ posttreatment with MCC950, neurons were subjected to Oxygen-Glucose Deprivation (OGD) for 2 h and then reperfusion for 20 h. Immunofluorescence was used to determine the expression of NLRP3, ASC, and cleaved caspase-1 in neurons. In vivo, SCI model mice were established with a 5 g weight-drop method. MCC950 was intraperitoneally injected at 0, 2, 4, 6, 8, 10, and 12 days after SCI. Basso Mouse Scale (BMS) scores and footprint assays were used to assess motor function. Paw withdrawal threshold and tail-flick latency were used to assess somatosensory function. H&E, Nissl, and TUNEL staining were used to measure histological changes and apoptosis at 3 days after SCI, and scar formation was observed by Masson staining and GFAP immunohistochemical analysis at 28 days after SCI. RESULTS: Immunofluorescence analysis confirmed that MCC950 inhibited OGD-induced activation of the NLRP3 inflammasome in neurons. Behavioral tests, Masson staining, and GFAP immunohistochemical analysis showed that MCC950-treated mice had improved neuronal functional recovery and reduced scar formation at 28 days after SCI. H&E, Nissl, and TUNEL staining confirmed that there were more living neurons and fewer apoptotic neurons in MCC950-treated mice than control mice at 3 days after SCI. CONCLUSION: These results reveal that MCC950 exerts neuroprotective effects by reducing neuronal apoptosis, preserving the survival of the remaining neurons, attenuating the severity of the damage, and promoting the recovery of motor function after SCI.
