Astragaloside IV alleviates cytarabine-induced intestinal mucositis by remodeling macrophage polarization through AKT signaling.

BACKGROUND: Intestinal mucositis (IM) is one of the common side effects of chemotherapy with Cytarabine (Ara-C) and contributes to the major dose-limiting factor of chemotherapy, while the effective drug for IM is little. Astragalus, one of the main active components extrated from the roots of Astragalus membranaceus (AS-IV), is a common Chinese herbal medicine used in gastrointestinal diseases. However, the effect and mechanism of AS-IV on IM is unclear. Accumulating evidence suggests that M1 macrophages play a pivotal role in IM progression. PURPOSE: The purpose of the study was to explore the protection of AS-IV and its potential molecular mechanism on intestinal mucositis injury induced by Ara-C. METHOD: The protective effect of AS-IV was investigated in LPS-induced macrophages and Ara-C-induced intestinal mucositis mouse model. H&E, immunofluorescence and western blotting were used to evaluate the damage in different doses of Ara-C. Silencing AKT targeted by siRNA was performed to explore the potential mechanisms regulating macrophage polarization effect of Ara-C, which was investigated by CCK-8, immunofluorescence and western blotting. Flow cytometry, immunofluorescence and Western blotting were used to detect macrophage surface marker proteins and inflammatory genes to explore the potential molecular mechanism of AS-IV regulating macrophage polarization. RESULTS: The Cytarabine intervention at dose of 100mg/kg significantly induced IM in mice, with the ileum the most obvious site of injury, accompanied by decreased intestinal barrier, intestinal macrophage polarization to M1 and inflammation response. The administration of AS-IV improved weight loss, food intake, ileal morphological damage, intestinal barrier destruction and inflammatory factor release in mice induced by Ara-c, and also suppressed macrophage polarization to M1, regulating in phenotypic changes in macrophages. In vitro, the expression of M1 macrophage surface marker protein was markedly decreased in LPS-induced macrophages after silencing AKT. Similarly, the western blotting of intestinal tissues and molecular docking indicated that the key mechanisms of AS-IV were remodel AKT signaling, and finally regulating M1 macrophages and decrease inflammation response. CONCLUSION: Our study highlights that AS-IV exerts protective effect in Ara-C-induced IM through inhibit polarization to M1 macrophages based on AKT, and AS-IV may serve as a novel AKT inhibitor to counteract the intestinal adverse effects of chemotherapeutic agents.

[Animal Model Establishment and Its Mechanism of Cytarabine-Iduced Myelosuppression].

OBJECTIVE: To establish an optimized model of bone marrow suppression induced by cytarabine (Ara-C) in C57BL/6 mice and preliminarily explore the mechanism of myelosuppression based on the cycle and apoptosis of BMNC. METHODS: C57BL/6 mice were intraperitoneally injected with Ara-C 50, 100 and 200 mg/kg for 7 days, respectively. The survival rate and body weight of C57BL/6 mice were monitored. The number of peripheral blood cells and bone marrow nucleated cells (BMNC) was detected, and the morphology of bone marrow, thymus and spleen were measured on the 7th, 14th and 21st day of the experiment. The cycle and apoptosis of BMNC were also detected by flow cytometry. RESULTS: Ara-C 200 mg/kg caused 46.7% mortality in mice, and other doses had no significant effect on mortality. All doses of Ara-C induced bone marrow suppression in mice, as shown by a decrease in the number of peripheral blood cells (WBC, Neu, RBC, PLT) and BMNC (P<0.05), decrease in bone marrow hyperplasia, accompanied by immunosuppression and compensatory hematopoiesis of the spleen, and the above manifestations and duration were dose-dependent. Among them, the myelosuppression caused by Ara-C 50 mg/kg recovered quickly, and caused by Ara-C 200 mg/kg was too severe. The result of flow cytometry showed that Ara-C could cause S and G2/m arrest and increased apoptosis in BMNC. CONCLUSION: Ara-C can induce myelosuppression in mice with a dose-dependent severity and duration, and the model of myelosuppression with Ara-C 100 mg/kg is more optimized. The mechanism is related to the inhibition of BMNC proliferation and the promotion of apoptosis.