Department of Biomedical and Neuromotor Science, University of Bologna, Piazza Di Porta San Donato 2, 40126, Bologna, Italy.
Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, 10314, USA.
J Neurodev Disord. 2024 Nov 26;16(1):65. doi: 10.1186/s11689-024-09583-4.
Mutations in the X-linked CDKL5 gene underlie a severe epileptic encephalopathy, CDKL5 deficiency disorder (CDD), characterized by gross motor impairment, autistic features and intellectual disability. Absence of Cdkl5 negatively impacts neuronal proliferation, survival, and maturation in in vitro and in vivo models, resulting in behavioral deficits in the Cdkl5 KO mouse. While there is no targeted therapy for CDD, several studies showed that treatments enabling an increase in brain BDNF levels give rise to structural and behavioral improvements in Cdkl5 KO mice. P021, a tetra-peptide derived from the biologically active region of the human ciliary neurotrophic factor (CNTF), was found to enhance neurogenesis and synaptic plasticity by promoting an increase in BDNF expression in preclinical models of brain disorders, such as Alzheimer's disease and Down syndrome, resulting in a beneficial therapeutic effect. Considering the positive actions of P021 on brain development and cognition associated with increased BDNF expression, the present study aimed to evaluate the possible beneficial effect of treatment with P021 in an in vitro and in vivo model of CDD.
We used SH-CDKL5-KO cells as an in vitro model of CDD to test the efficacy of P021 on neuronal proliferation, survival, and maturation. In addition, both young and adult Cdkl5 KO mice were used to evaluate the in vivo effects of P021, on neuroanatomical and behavioral defects.
We found that P021 treatment was effective in restoring neuronal proliferation, survival, and maturation deficits, as well as alterations in the GSK3β signaling pathway, features that characterize a human neuronal model of CDKL5 deficiency. Unexpectedly, chronic in vivo P021 treatment failed to increase BDNF levels and did not improve neuroanatomical defects in Cdkl5 KO mice, resulting in limited behavioral benefit.
At present, it remains to be understood whether initiating the treatment prenatally, or prolonging the duration of treatment will be necessary in order to achieve similar results in vivo in CDD mice to those obtained in vitro.
X 连锁的 CDKL5 基因突变导致严重的癫痫性脑病，即 CDKL5 缺乏症（CDD），其特征是运动功能严重受损、自闭症特征和智力残疾。体外和体内模型显示 Cdkl5 的缺失会影响神经元的增殖、存活和成熟，导致 Cdkl5 KO 小鼠出现行为缺陷。虽然目前尚无针对 CDD 的靶向治疗方法，但多项研究表明，能够增加脑 BDNF 水平的治疗方法会导致 Cdkl5 KO 小鼠出现结构和行为改善。P021 是一种源自人睫状神经营养因子（CNTF）生物活性区域的四肽，在阿尔茨海默病和唐氏综合征等脑部疾病的临床前模型中，通过促进 BDNF 表达的增加，被发现可增强神经发生和突触可塑性，从而产生有益的治疗效果。考虑到 P021 对与 BDNF 表达增加相关的大脑发育和认知的积极作用，本研究旨在评估 P021 治疗 CDD 的体外和体内模型的可能有益效果。
我们使用 SH-CDKL5-KO 细胞作为 CDD 的体外模型，以测试 P021 对神经元增殖、存活和成熟的疗效。此外，还使用年轻和成年 Cdkl5 KO 小鼠来评估 P021 对神经解剖和行为缺陷的体内影响。
我们发现 P021 治疗可有效恢复神经元增殖、存活和成熟缺陷，以及 GSK3β 信号通路的改变，这些特征是 CDKL5 缺乏的人类神经元模型的特征。出乎意料的是，慢性体内 P021 治疗未能增加 BDNF 水平，也未能改善 Cdkl5 KO 小鼠的神经解剖缺陷，导致行为获益有限。
目前尚不清楚是否需要在产前开始治疗，或者延长治疗时间，以便在 CDD 小鼠中获得与体外相似的体内结果。
