Macrophage polarization is closely associated with the inflammatory processes involved in the development and chemoresistance of colorectal cancer (CRC). M2 macrophages, the predominant subtype of tumor-associated macrophages (TAMs) in a wide variety of malignancies, have been demonstrated to promote the resistance of CRC to multiple chemotherapeutic drugs, such as 5-fluorouracil (5-FU). In our study, we investigated the potential of 23-Hydroxybetulinic Acid (23-HBA), a significant active component of Pulsatilla chinensis (P. chinensis), to inhibit the polarization of M2 macrophages induced by IL-4. Our results showed that 23-HBA reduced the expression of M2 specific marker CD206, while downregulating the mRNA levels of M2 related genes (CD206, Arg1, IL-10, and CCL2). Additionally, 23-HBA effectively attenuated the inhibitory effects of the conditioned medium from M2 macrophages on apoptosis in colorectal cancer SW480 cells. Mechanistically, 23-HBA prevented the phosphorylation and nuclear translocation of the STAT6 protein, resulting in the inhibition of IL-10 release in M2 macrophages. Moreover, it interfered with the activation of the IL-10/STAT3/Bcl-2 signaling pathway in SW480 cells, ultimately reducing M2 macrophage-induced resistance to 5-FU. Importantly, depleting STAT6 expression in macrophages abolished the suppressive effect of 23-HBA on M2 macrophage polarization, while also eliminating its ability to decrease M2 macrophage-induced 5-FU resistance in cancer cells. Furthermore, 23-HBA significantly diminished the proportion of M2 macrophages in the tumor tissues of colorectal cancer mice, simultaneously enhancing the anti-cancer efficacy of 5-FU. The findings presented in this study highlight the capacity of 23-HBA to inhibit M2 macrophage polarization, a process that contributes to reduced 5-FU resistance in colorectal cancer.

巨噬细胞极化与结直肠癌（CRC）的发生和化疗耐药相关的炎症过程密切相关。 M2 巨噬细胞是多种恶性肿瘤中肿瘤相关巨噬细胞 (TAM) 的主要亚型，已被证明可促进 CRC 对多种化疗药物（例如 5-氟尿嘧啶 (5-FU)）的耐药性。在我们的研究中，我们研究了白头翁 ( Pulsatilla chinensis ) 的重要活性成分 23-羟基桦木酸 (23-HBA)抑制 IL-4 诱导的 M2 巨噬细胞极化的潜力。我们的结果表明，23-HBA 降低了 M2 特异性标记物 CD206 的表达，同时下调了 M2 相关基因（CD206、Arg1、IL-10 和 CCL2）的 mRNA 水平。此外，23-HBA 有效减弱 M2 巨噬细胞条件培养基对结直肠癌 SW480 细胞凋亡的抑制作用。从机制上讲，23-HBA 阻止 STAT6 蛋白的磷酸化和核转位，从而抑制 M2 巨噬细胞中 IL-10 的释放。此外，它干扰 SW480 细胞中 IL-10/STAT3/Bcl-2 信号通路的激活，最终降低 M2 巨噬细胞诱导的对 5-FU 的耐药性。重要的是，消除巨噬细胞中STAT6的表达消除了23-HBA对M2巨噬细胞极化的抑制作用，同时也消除了其降低癌细胞中M2巨噬细胞诱导的5-FU耐药性的能力。此外，23-HBA显着降低结直肠癌小鼠肿瘤组织中M2巨噬细胞的比例，同时增强5-FU的抗癌功效。本研究的结果强调了 23-HBA 抑制 M2 巨噬细胞极化的能力，这一过程有助于降低结直肠癌中的 5-FU 耐药性。