LRRK2-targeting therapeutics that inhibit LRRK2 kinase activity have advanced to clinical trials in idiopathic Parkinson’s disease (iPD). LRRK2 phosphorylates Rab10 on endolysosomes in phagocytic cells to promote some types of immunological responses. The identification of factors that regulate LRRK2-mediated Rab10 phosphorylation in iPD, and whether phosphorylated-Rab10 levels change in different disease states, or with disease progression, may provide insights into the role of Rab10 phosphorylation in iPD and help guide therapeutic strategies targeting this pathway. Capitalizing on past work demonstrating LRRK2 and phosphorylated-Rab10 interact on vesicles that can shed into biofluids, we developed and validated a high-throughput single-molecule array assay to measure extracellular pT73-Rab10. Ratios of pT73-Rab10 to total Rab10 measured in biobanked serum samples were compared between informative groups of transgenic mice, rats, and a deeply phenotyped cohort of iPD cases and controls. Multivariable and weighted correlation network analyses were used to identify genetic, transcriptomic, clinical, and demographic variables that predict the extracellular pT73-Rab10 to total Rab10 ratio. pT73-Rab10 is absent in serum from Lrrk2 knockout mice but elevated by LRRK2 and VPS35 mutations, as well as SNCA expression. Bone-marrow transplantation experiments in mice show that serum pT73-Rab10 levels derive primarily from circulating immune cells. The extracellular ratio of pT73-Rab10 to total Rab10 is dynamic, increasing with inflammation and rapidly decreasing with LRRK2 kinase inhibition. The ratio of pT73-Rab10 to total Rab10 is elevated in iPD patients with greater motor dysfunction, irrespective of disease duration, age, sex, or the usage of PD-related or anti-inflammatory medications. pT73-Rab10 to total Rab10 ratios are associated with neutrophil degranulation, antigenic responses, and suppressed platelet activation. The extracellular serum ratio of pT73-Rab10 to total Rab10 is a novel pharmacodynamic biomarker for LRRK2-linked innate immune activation associated with disease severity in iPD. We propose that those iPD patients with higher serum pT73-Rab10 levels may benefit from LRRK2-targeting therapeutics that mitigate associated deleterious immunological responses.

中文翻译：

---

血清中 LRRK2 激酶活性的单分子阵列测量将帕金森病的严重程度与周围炎症联系起来


抑制 LRRK2 激酶活性的 LRRK2 靶向疗法已进入特发性帕金森病 (iPD) 的临床试验。 LRRK2 磷酸化吞噬细胞内溶酶体上的 Rab10，以促进某些类型的免疫反应。鉴定 iPD 中调节 LRRK2 介导的 Rab10 磷酸化的因素，以及磷酸化 Rab10 水平是否在不同疾病状态或疾病进展中发生变化，可能有助于深入了解 Rab10 磷酸化在 iPD 中的作用，并有助于指导针对该途径的治疗策略。利用过去证明 LRRK2 和磷酸化 Rab10 在可以流入生物液的囊泡上相互作用的工作，我们开发并验证了一种高通量单分子阵列测定法来测量细胞外 pT73-Rab10。在转基因小鼠、大鼠的信息组以及 iPD 病例和对照的深度表型队列之间比较生物库血清样本中测量的 pT73-Rab10 与总 Rab10 的比率。使用多变量和加权相关网络分析来识别预测细胞外 pT73-Rab10 与总 Rab10 比率的遗传、转录组、临床和人口统计学变量。 Lrrk2 敲除小鼠的血清中不存在 pT73-Rab10，但由于 LRRK2 和 VPS35 突变以及 SNCA 表达而升高。小鼠骨髓移植实验表明，血清 pT73-Rab10 水平主要来自循环免疫细胞。 pT73-Rab10 与总 Rab10 的细胞外比率是动态的，随着炎症的增加而增加，并随着 LRRK2 激酶抑制的增加而迅速减少。 在运动功能障碍较严重的 iPD 患者中，pT73-Rab10 与总 Rab10 的比率升高，无论病程、年龄、性别或是否使用 PD 相关药物或抗炎药物。 pT73-Rab10 与总 Rab10 的比率与中性粒细胞脱颗粒、抗原反应和抑制血小板活化有关。细胞外血清中 pT73-Rab10 与总 Rab10 的比率是与 iPD 疾病严重程度相关的 LRRK2 相关先天免疫激活的新型药效生物标志物。我们认为，那些血清 pT73-Rab10 水平较高的 iPD 患者可能会受益于 LRRK2 靶向治疗，从而减轻相关的有害免疫反应。