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Abstract：
BACKGROUND: Glioblastoma (GBM) remains a challenging brain tumor to treat, with limited response to PD-1 immunotherapy due to tumor-associated macrophages (TAMs), specifically the M2 phenotype. This study explores the potential of MS4A4A (membrane spanning four domains, subfamily A, member 4A) inhibition in driving M2 macrophage polarization toward the M1 phenotype via the ferroptosis pathway to enhance the effectiveness of immunotherapy in GBM.
METHODS: Single-cell RNA sequencing and spatial transcriptomic analyses were employed to characterize M2 macrophages and MS4A4A expression in GBM. In vitro studies utilizing TAM cultures, flow cytometry, and western blot validations were conducted to assess the impact of MS4A4A on the tumor immune microenvironment and M2 macrophage polarization. In vivo models, including subcutaneous and orthotopic transplantation in mice, were utilized to evaluate the effects of MS4A4A knockout and combined immune checkpoint blockade (ICB) therapy on tumor growth and response to PD-1 immunotherapy.
RESULTS: Distinct subsets of GBM-associated macrophages were identified, with spatial distribution in tumor tissue elucidated. In vivo experiments demonstrated that inhibiting MS4A4A and combining ICB therapy effectively inhibited tumor growth, reshaped the tumor immune microenvironment by reducing M2 TAM infiltration and enhancing CD8+ T-cell infiltration, ultimately leading to complete tumor eradication.
CONCLUSIONS: MS4A4A inhibition shows promise in converting M2 macrophages to M1 phenotype via ferroptosis, decreasing M2-TAM infiltration, and enhancing GBM response to PD-1 immunotherapy. These findings offer a novel approach to developing more effective immunotherapeutic strategies for GBM.
METHODS: Single-cell RNA sequencing and spatial transcriptomic analyses were employed to characterize M2 macrophages and MS4A4A expression in GBM. In vitro studies utilizing TAM cultures, flow cytometry, and western blot validations were conducted to assess the impact of MS4A4A on the tumor immune microenvironment and M2 macrophage polarization. In vivo models, including subcutaneous and orthotopic transplantation in mice, were utilized to evaluate the effects of MS4A4A knockout and combined immune checkpoint blockade (ICB) therapy on tumor growth and response to PD-1 immunotherapy.
RESULTS: Distinct subsets of GBM-associated macrophages were identified, with spatial distribution in tumor tissue elucidated. In vivo experiments demonstrated that inhibiting MS4A4A and combining ICB therapy effectively inhibited tumor growth, reshaped the tumor immune microenvironment by reducing M2 TAM infiltration and enhancing CD8+ T-cell infiltration, ultimately leading to complete tumor eradication.
CONCLUSIONS: MS4A4A inhibition shows promise in converting M2 macrophages to M1 phenotype via ferroptosis, decreasing M2-TAM infiltration, and enhancing GBM response to PD-1 immunotherapy. These findings offer a novel approach to developing more effective immunotherapeutic strategies for GBM.
摘要：
背景：胶质母细胞瘤（GBM）仍然是一种具有挑战性的脑肿瘤，由于肿瘤相关巨噬细胞（TAMs），对PD-1免疫疗法的反应有限，特别是M2表型。本研究探讨了MS4A4A(跨四个结构域的膜，亚科A,成员4A）通过铁凋亡途径驱动M2巨噬细胞向M1表型极化，以增强GBM中免疫疗法的有效性。
方法：采用单细胞RNA测序和空间转录组学分析来表征GBM中M2巨噬细胞和MS4A4A的表达。利用TAM培养物的体外研究，流式细胞术,进行免疫印迹验证以评估MS4A4A对肿瘤免疫微环境和M2巨噬细胞极化的影响。体内模型,包括小鼠皮下和原位移植，用于评估MS4A4A敲除和联合免疫检查点阻断（ICB）疗法对肿瘤生长和对PD-1免疫疗法的反应的影响。
结果：确定了GBM相关巨噬细胞的不同亚群，阐明了肿瘤组织中的空间分布。体内实验表明，抑制MS4A4A并结合ICB治疗有效抑制肿瘤生长，通过减少M2TAM浸润和增强CD8+T细胞浸润重塑肿瘤免疫微环境，最终导致肿瘤完全根除。
结论：MS4A4A抑制显示通过铁凋亡将M2巨噬细胞转化为M1表型的希望，减少M2-TAM入渗，并增强GBM对PD-1免疫疗法的反应。这些发现为开发更有效的GBM免疫治疗策略提供了新的方法。
方法：采用单细胞RNA测序和空间转录组学分析来表征GBM中M2巨噬细胞和MS4A4A的表达。利用TAM培养物的体外研究，流式细胞术,进行免疫印迹验证以评估MS4A4A对肿瘤免疫微环境和M2巨噬细胞极化的影响。体内模型,包括小鼠皮下和原位移植，用于评估MS4A4A敲除和联合免疫检查点阻断（ICB）疗法对肿瘤生长和对PD-1免疫疗法的反应的影响。
结果：确定了GBM相关巨噬细胞的不同亚群，阐明了肿瘤组织中的空间分布。体内实验表明，抑制MS4A4A并结合ICB治疗有效抑制肿瘤生长，通过减少M2TAM浸润和增强CD8+T细胞浸润重塑肿瘤免疫微环境，最终导致肿瘤完全根除。
结论：MS4A4A抑制显示通过铁凋亡将M2巨噬细胞转化为M1表型的希望，减少M2-TAM入渗，并增强GBM对PD-1免疫疗法的反应。这些发现为开发更有效的GBM免疫治疗策略提供了新的方法。
