Exendin-4 alleviates the severity of atherosclerosis. This process may be achieved by promoting the secretion of myeloid-derived suppressor cells (MDSCs) in the bone marrow and peripheral blood of atherosclerotic ApoE-/- mice, regulating the ratio of inflammatory factors in the body, reducing mouse body weight, and lowering blood lipids.

Thirty male ApoE-/- mice were randomly divided into five groups (n = 6 per group): control group (CON), model group (MOD), Exendin-4 intervention group (MOD/Ex-4), Exendin-9-39 intervention group (MOD/Ex-9-39), and Exendin-4 + Exendin-9-39 combined intervention group (MOD/Ex-4 + Ex-9-39). After 4 weeks of drug intervention, changes in aortic plaque were observed using Oil Red O staining and H&E staining. Flow cytometry was employed to detect the content of myeloid-derived suppressor cells (MDSCs) in bone marrow and peripheral blood. ELISA was utilized to measure the concentrations of inflammatory factors in mouse peripheral blood plasma, while RT-qPCR was employed to quantify the expression levels of inflammatory factors in the spleen. Pearson correlation analysis was conducted to assess the relationship between MDSCs and inflammatory factors.

To investigate the impact of the glucagon-like peptide-1 (GLP-1) receptor agonist Exendin-4 on the proportion of myeloid-derived suppressor cells (MDSCs) in male ApoE-/- mice, and investigate alterations in the concentrations of inflammatory factors in plasma and spleen tissues and assess their correlation with MDSCs.

Mice in the MOD group had significantly higher body weight compared to the CON group, with a statistically significant difference (P<0.05). Following Exendin-4 intervention, body weight was reduced compared to the MOD group (P<0.05). Additionally, Exendin-4 treatment led to a significant reduction in atherosclerotic plaque compared to the MOD group (P<0.001). After Exendin-4 intervention, the proportion of MDSCs in the bone marrow was higher than in the MOD group (P<0.001), and the proportion of MDSCs in peripheral blood was significantly higher than in the MOD group (P<0.05). Further investigation revealed that Exendin-4 could regulate lipid levels in mice, decreasing concentrations of TG (P<0.01), TC (P<0.0001), and LDL-C (P<0.0001), while increasing HDL-C concentrations (P<0.01). Moreover, after Exendin-4 treatment, the level of the cytokine IL-6 in peripheral plasma was significantly lower compared to the MOD group (P<0.0001), while levels of IL-10 and TGF-β were significantly higher compared to the MOD group (P<0.0001). In the spleen, levels of the cytokines IL-10 (P<0.0001) and TGF-β (P<0.001) were significantly increased compared to the MOD group. Pearson correlation analysis showed that the proportion of MDSCs in peripheral blood was positively correlated with IL-10 and TGF-β levels in both the spleen and peripheral blood. Additionally, the proportion of MDSCs in the bone marrow was positively correlated with IL-10 and TGF-β levels in the spleen and peripheral blood.