4 research outputs found
Neural precursor cells rescue symptoms of Rett syndrome by activation of the Interferon γ pathway.
No full textThe beneficial effects of Neural Precursor Cell (NPC) transplantation in several neurological disorders are well established and they are generally mediated by the secretion of immunomodulatory and neurotrophic molecules. We therefore investigated whether Rett syndrome (RTT), that represents the first cause of severe intellectual disability in girls, might benefit from NPC-based therapy. Using in vitro co-cultures, we demonstrate that, by sensing the pathological context, NPC-secreted factors induce the recovery of morphological and synaptic defects typical of Mecp2 deficient neurons. In vivo, we prove that intracerebral transplantation of NPCs in RTT mice significantly ameliorates neurological functions. To uncover the molecular mechanisms underpinning the mediated benefic effects, we analyzed the transcriptional profile of the cerebellum of transplanted animals, disclosing the possible involvement of the Interferon γ (IFNγ) pathway. Accordingly, we report the capacity of IFNγ to rescue synaptic defects, as well as motor and cognitive alterations in Mecp2 deficient models, thereby suggesting this molecular pathway as a potential therapeutic target for RTT. [Abstract copyright: © 2024. The Author(s).
Neural Precursor Cells as a potential therapeutic approach for Rett Syndrome: identification of the involved molecular mechanisms
No full textRett syndrome (RTT) is a rare neurodevelopmental disorder, mostly caused by sporadic mutations in the X linked MECP2 gene. RTT, the primary cause of severe intellectual disability in females, currently lacks a cure; nonetheless, the FDA recently approved the first therapy utilizing a tripeptide of IGF1.
Neural Precursor Cells (NPCs) can sense the pathological environment when transplanted in it, they secrete beneficial factors that promote immunomodulation, neuroprotection, brain plasticity. These healing functions render NPCs an interesting cellular therapy for treating several neurodegenerative disorders. Since no study addressed their efficacy in neurodevelopmental diseases, we investigated their therapeutic potential in RTT, demonstrating their efficacy in vitro and in vivo. In vivo, we proved significant amelioration of the cognitive and motor defects of RTT mice, together with an increased lifespan, after NPCs transplantation. Through a transwell-based co-culture system, we observed that NPCs promote morphological and synaptic rescues in Mecp2 null neurons, demonstrating that NPCs-mediated beneficial effects arise through “bystander” and paracrine mechanisms.
RNA-seq studies of transplanted mice identified a candidate molecule involved in the benefic effects. Likely, the observed beneficial effects depend on the activation of different pathways. Therefore, my PhD studies are focused on exploiting a transwell-based co-culture system to identify the molecular mechanisms set in motion by NPCs in Mecp2-KO neurons.
Through a Bulk RNA-seq performed on immature neurons maintained, or not, in co-culture with NPCs we demonstrated positive effects on KO neurons when exposed to the NPCs secreted factors (e.g., enhancement in the synaptic compartment, typically defective in Rett neurons). Simultaneously, to understand which molecules are secreted by NPCs when exposed to the Mecp2-KO environment, their transcriptional profile is being investigated.
All data will be presented in the poster session to illustrate the value of this cellular approach in treating RTT and/or in identifying new defective pathways with putative therapeutic value
Identification of novel molecules by which Mecp2 knock-out astrocytes exert a synaptotoxic action on neurons
No full textBackground. Over 95% of Rett syndrome (RTT) cases are given by mutations in the X-linked methyl-CpG-binding protein 2 (MECP2) gene. Although initial studies supported a role for MeCP2 exclusively in neurons, several recent data indicate the involvement also of astrocytes, which can affect neuronal maturation through non-cell autonomous mechanisms. Nevertheless, many aspects of astrocyte dysfunctions in RTT remain still unknown.
Objectives: According to the crucial role of astrocytes in promoting synapse formation and functioning, and the profound synaptic alterations in RTT, we investigated the influence of Mecp2 null astrocytes on synaptic maturation and we explored the involvement of two molecules in the occurrence of synaptic defects.
Methods: To reproduce in vitro the heterozygous condition of RTT brains, we tested the effect of null astrocytes or their conditioned medium (ACM) on WT neurons. By immunufluorescence we analysed pre- and post-synaptic densities in cultured neurons. RNA sequencing was used to gain insight into the involved molecular mechanisms.
Results: We demonstrated that Mecp2 null astrocytes dramatically affect synaptogenesis and synaptic functionality, and molecular analyses highlighted in null astrocytes both the activation of an inflammatory pathway and a concomitant reduction in cholesterol metabolism. As validation of these underscored molecular mechanisms, we proved that Mecp2 null astrocytes, when in culture with WT neurons, express and secrete excessive levels of Interleukin-6 (IL-6), which exerts a synaptotoxic action. Indeed, we found that the recombinant IL-6 causes synaptic defects in WT neurons and, coherently, a neutralizing IL-6 antibody rescues KO astrocyte-mediated synaptic alterations. In parallel, we observed a reduced cholesterol metabolism in Mecp2 null astrocytes and demonstrated that cholesterol supplementation reverts synaptic defects.
Conclusion: These in vitro data constitute the rationale for studying the pathogenic role of IL-6 and cholesterol in Mecp2 deficient mice and explore novel therapeutic strategies targeting these two factors to improve RTT symptoms
Interpreting the rich dialogue between astrocytes and neurons: An overview in Rett syndrome
No full textRett syndrome (RTT) is a severe neurodevelopmental disorder primarily affecting females, with an incidence of 1 in 10,000 live births. It is caused mainly by de novo mutations in the X-linked MECP2 gene, which encodes methyl-CpG binding protein 2 (Mecp2), a key epigenetic regulator. MECP2 mutations have profound impacts on neurons, which exhibit morphological, synaptic and functional impairments. However, more recent evidence highlights a crucial role of astrocytes in RTT pathogenesis. Indeed, RTT astrocytes exhibit structural and functional impairments, failing to support neuronal growth and function through non-cell autonomous mechanisms. Studies reveal that MECP2 deficient astrocytes secrete abnormal factors that impair neuronal growth and synaptic function. Furthermore, they show dysregulated calcium signalling, disrupted glutamate and potassium homeostasis, and increased inflammatory responses, all of which contribute to neuronal dysfunction. Understanding these neuron-astrocyte interactions may offer novel therapeutic targets for RTT. In the review we aim at presenting the current knowledge of astrocyte-neuron crosstalk in RTT, describing the different mechanisms highlighted so far through which MECP2 mutant astrocytes impair neurons. Finally, we discuss existing and prospective methodological approaches for investigating cell-to-cell communication in RTT
