背景:诱导多能干细胞衍生的小胶质细胞(iMGL)是研究健康和疾病中小胶质细胞功能的极好工具。然而,由于iMGL的分化和存活高度依赖于集落刺激因子1受体(CSF1R)信号,使用iMGL很难研究与CSF1R致病缺陷相关的小胶质细胞功能障碍。
方法:对现有的iMGL协议进行了系列修改,包括但不限于生长因子组合的变化以驱动小胶质细胞分化,直到成功从带有轴突球体和色素胶质细胞(ALSP)的成人发作的白质脑病患者中衍生出小胶质细胞样细胞,该患者携带c.2350G>A(p。V784M)CSF1R变体。使用健康的控制线,通过细胞产量评估验证了新的iMGL方案的质量,小胶质细胞标记表达的测量,转录组学与原发性小胶质细胞的比较,并评估炎症和吞噬活性。同样,与健康对照iMGL相比,进行了ALSP患者来源的iMGL的分子和功能表征。
结果:新设计的方案允许产生iMGL,其与培养的原代人类小胶质细胞具有增强的转录组相似性,并且与原始方案相比,具有更高的清除和炎症能力,产量约为三倍。使用这个协议,与来自健康对照的那些相比,在来自ALSP患者的iMGL中观察到CSF1R自磷酸化和细胞表面表达降低。此外,ALSP患者来源的iMGL出现了伴随嘌呤能受体P2Y12(P2RY12)表达时间减少的迁移缺陷,内化髓鞘的能力增强,以及对Pam3CSK4的炎症反应增强。P2RY12表达不良被证实是CSF1R单倍体功能不全的结果,由于在成熟对照iMGL中CSF1R敲低或抑制后也观察到此特征,以及在CSF1RWT/KO和CSF1RWT/E633KiMGL中与其各自的等基因对照相比。
结论:我们优化了预先存在的iMGL协议,生成一个强大的工具来研究小胶质细胞参与人类神经系统疾病。使用优化的协议,我们首次从携带致病性CSF1R变体的ALSP患者中产生iMGL,初步表征指向迁移中的功能改变,吞噬和炎症活动。
BACKGROUND: Induced pluripotent stem cell-derived microglia (iMGL) represent an excellent tool in studying microglial function in health and disease. Yet, since differentiation and survival of iMGL are highly reliant on colony-stimulating factor 1 receptor (CSF1R) signaling, it is difficult to use iMGL to
study microglial dysfunction associated with pathogenic defects in CSF1R.
METHODS: Serial modifications to an existing iMGL protocol were made, including but not limited to changes in growth factor combination to drive microglial differentiation, until successful derivation of microglia-like cells from an adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) patient carrying a c.2350G > A (p.V784M) CSF1R variant. Using healthy control lines, the quality of the new iMGL protocol was validated through cell yield assessment, measurement of microglia marker expression, transcriptomic comparison to primary microglia, and evaluation of inflammatory and phagocytic activities. Similarly, molecular and functional characterization of the ALSP patient-derived iMGL was carried out in comparison to healthy control iMGL.
RESULTS: The newly devised protocol allowed the generation of iMGL with enhanced transcriptomic similarity to cultured primary human microglia and with higher scavenging and inflammatory competence at ~ threefold greater yield compared to the original protocol. Using this protocol, decreased CSF1R autophosphorylation and cell surface expression was observed in iMGL derived from the ALSP patient compared to those derived from healthy controls. Additionally, ALSP patient-derived iMGL presented a migratory defect accompanying a temporal reduction in purinergic receptor P2Y12 (P2RY12) expression, a heightened capacity to internalize myelin, as well as heightened inflammatory response to Pam3CSK4. Poor P2RY12 expression was confirmed to be a consequence of CSF1R haploinsufficiency, as this feature was also observed following CSF1R knockdown or inhibition in mature control iMGL, and in CSF1RWT/KO and CSF1RWT/E633K iMGL compared to their respective isogenic controls.
CONCLUSIONS: We optimized a pre-existing iMGL protocol, generating a powerful tool to
study microglial involvement in human neurological diseases. Using the optimized protocol, we have generated for the first time iMGL from an ALSP patient carrying a pathogenic CSF1R variant, with preliminary characterization pointing toward functional alterations in migratory, phagocytic and inflammatory activities.