Synaptic adhesion molecule protocadherin-γC5 mediates ß-amyloid-induced neuronal hyperactivity and cognitive deficits in Alzheimer's disease.

Neuronal hyperactivity induced by ß-amyloid (Aß) is an early pathological feature in Alzheimer's disease (AD) and contributes to cognitive decline in AD progression. However, the underlying mechanisms are still unclear. Here, we revealed that Aß increased the expression level of synaptic adhesion molecule protocadherin-γC5 (Pcdh-γC5) in a Ca2+ -dependent manner, associated with aberrant elevation of synapses in both Aß-treated neurons in vitro and the cortex of APP/PS1 mice in vivo. By using Pcdhgc5 gene knockout mice, we demonstrated the critical function of Pcdh-γC5 in regulating neuronal synapse formation, synaptic transmission, and cognition. To further investigate the role of Pcdh-γC5 in AD pathogenesis, the aberrantly enhanced expression of Pcdh-γC5 in the brain of APP/PS1 mice was knocked down by shRNA. Downregulation of Pcdh-γC5 efficiently rescued neuronal hyperactivity and impaired cognition in APP/PS1 mice. Our findings revealed the pathophysiological role of Pcdh-γC5 in mediating Aß-induced neuronal hyperactivity and cognitive deficits in AD and identified a novel mechanism underlying AD pathogenesis.

Sporopollenin exine capsules modulate the function of microglial cells.

Immune cells are the housekeepers of the human body. They protect the body from pathogens, cellular damage, and foreign matter. Proper activation of immune cells is of great significance to diseases such as infection, inflammation, and neurodegeneration. However, excessive activation of cells can be detrimental. An ideal biomaterial could enhance the cellular immune function without proinflammation. In this work, we used sporopollenin exine capsules (SEC) from pollen to promote functions of primary microglia, a typical resident immune cell of the brain. We found that microglia aggregated around SEC and did not undergo any proinflammation. SEC improved the viability, migration, phagocytosis, and anti-inflammatory ability of microglia. By exploring the underlying mechanism of microglial activation without the production of cytotoxic pro-inflammatory cytokines, we found that SEC protects microglia against inflammation induced by lipopolysaccharide (LPS), an immunostimulatory factor, through the toll-like receptor 4 (TLR4) signaling pathway in a myeloid differentiation factor 88-dependent manner. These findings might shed light on the potential application of SEC in microglia transplantation for treatment of microglia-associated degenerative central nervous system diseases.

Microglial repopulation reverses cognitive and synaptic deficits in an Alzheimer's disease model by restoring BDNF signaling.

Over the past decade, compelling genetic evidence has highlighted the crucial role of microglial dysregulation in the development of Alzheimer's disease (AD). As resident immune cells in the brain, microglia undergo dystrophy and senescence during the chronic progression of AD. To explore the potential therapeutic benefits of replenishing the brain with new microglia in AD, we utilized the CSF1R inhibitor PLX3397 to deplete existing microglia and induce repopulation after inhibitor withdrawal in 5xFAD transgenic mice. Our findings revealed the remarkable benefits of microglial repopulation in ameliorating AD-associated cognitive deficits, accompanied by a notable elevation in synaptic proteins and an enhancement of hippocampal long-term potentiation (LTP). Additionally, we observed the profound restoration of microglial morphology and synaptic engulfment following their self-renewal. The impact of microglial repopulation on amyloid pathology is dependent on the duration of repopulation. Transcriptome analysis revealed a high resemblance between the gene expression profiles of repopulated microglia from 5xFAD mice and those of microglia from WT mice. Importantly, the dysregulated neurotrophic signaling pathway and hippocampal neurogenesis in the AD brain are restored following microglial replenishment. Lastly, we demonstrated that the repopulation restores the expression of brain-derived neurotrophic factor (BDNF) in microglia, thereby contributing to synaptic plasticity. In conclusion, our findings provide compelling evidence to support the notion that microglial self-renewal confers substantial benefits to the AD brain by restoring the BDNF neurotrophic signaling pathway. Thus, targeted microglial repopulation emerges as a highly promising and novel therapeutic strategy for alleviating cognitive impairment in AD.

Minocycline protects against microgliopathy in a Csf1r haplo-insufficient mouse model of adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP).

BACKGROUND: Mutations in colony-stimulating factor 1 receptor (CSF1R) are known to cause adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP), which has been recently demonstrated as a primary microgliopathy characterized by cognitive impairment. Although the molecular mechanism underlying CSF1R-mediated microgliopathy remains unclear, therapeutic strategies have generally targeted modulation of microglial function. In particular, the microglial inhibitor, minocycline, has been shown to attenuate learning and memory deficits in several neurodegenerative diseases. The objectives of this study were to investigate the pathogenic mechanisms underlying ALSP and to explore the therapeutic effects of minocycline in an in vivo model of ALSP. We hypothesized that inhibiting microglial activation via minocycline could reverse the behavior and pathological defects in ALSP model mice. METHODS: We generated a Csf1r haploinsufficiency mouse model of ALSP using CRISPR/Cas9 genome editing and conducted electrophysiological recordings of long-term potentiation (LTP) and behavioral tests to validate the recapitulation of clinical ALSP characteristics in 8- to 11-month-old mice. RNA-sequencing was used to explore enriched gene expression in the molecular pathogenesis of ALSP. Microglial activation was assessed by immunofluorescent detection of Iba1 and CD68 in brain sections of male ALSP mice and pro-inflammatory activation and phagocytosis were assessed in Csf1r+/- microglia. Therapeutic effects were assessed by behavioral tests, histological analysis, and morphological examination after four weeks of intraperitoneal injection with minocycline or vehicle control in Csf1r+/- mice and wild-type control littermates. RESULTS: We found that synaptic function was reduced in LTP recordings of neurons in the hippocampal CA1 region, while behavioral tests showed impaired spatial and cognitive memory specifically in male Csf1r+/- mice. Increased activation, pro-inflammatory cytokine production, and enhanced phagocytic capacity were also observed in Csf1r+/- microglia. Treatment with minocycline could suppress the activation of Csf1r+/- microglia both in vitro and in vivo. Notably, the behavioral and pathological deficits in Csf1r+/- mice were partially rescued by minocycline administration, potentially due to inhibition of microglial inflammation and phagocytosis in Csf1r+/- mice. CONCLUSIONS: Our study shows that CSF1R deficiency results in aberrant microglial activation, characterized by a pro-inflammatory phenotype and enhanced phagocytosis of myelin. Our results also indicate that microglial inhibition by minocycline can ameliorate behavioral impairment and ALSP pathogenesis in CSF1R-deficient male mice, suggesting a potential therapeutic target for CSF1R-related leukoencephalopathy. Collectively, these data support that minocycline confers protective effects against CSF1R-related microgliopathy in male ALSP model mice.

Carboplatin-loaded surface modified-PLGA nanoparticles confer sustained inhibitory effect against retinoblastoma cell in vitro / Nanopartículas de PLGA com superfície modificada carregada com carboplatina conferem efeito inibitório sustentado contra células de retinoblastoma in vitro

ABSTRACT Purpose: To investigate the antiproliferative effect of carboplatin-loaded surface-modified poly(lactide-co-glycolide) on retinoblastoma cells. Methods: Carboplatin-loaded poly(lactide-co-glycolide) with or without sodium alginate surface modification was prepared using sodium alginate-poly(lactide-co-glycolide) and poly(lactide-co-glycolide). The zeta potential and carboplatin release behavior were investigated. The cellular uptake of the released drug was observed in the retinoblastoma cell line Y79. The inhibitory effect of carboplatin-loaded nanoparticles against the Y79 cell line was evaluated using methyl thiazolyl tetrazolium assay and western blot. Native carboplatin and void nanoparticles without carboplatin loading were used as controls. Results: The zeta potential was -(26.1 ± 3.1) mV for carboplatin-loaded poly(lactide-co-glycolide) and-(43.1 ± 8.1) mV for carboplatin-loaded sodium alginate-poly(lactide-co-glycolide). The burst release percentages of carboplatin-loaded poly(lactide-co-glycolide) and sodium alginate-poly(lactide-co-glycolide) were (40.0% ± 8.2%) and (18.9% ± 4.3%) at 24 hours, respectively. A significant difference was identified regarding drug release between carboplatin-loaded sodium alginate-poly(lactide-co-glycolide) and carboplatin-loaded poly(lactide-co-glycolide). Fluorescence detection revealed that intense uptake of carboplatin into the cytoplasm of the Y79 cell line that was exposed to carboplatin-loaded sodium alginate-poly(lactide-co-glycolide). Carboplatin-loaded poly(lactide-co-glycolide) or sodium alginate-poly(lactide-co-glycolide) exposure inhibited proliferating cell nuclear antigen expression in Y79 cells on day 3. Extension of exposure to day 5 revealed that the sodium alginate-poly(lactide-co-glycolide) surface modification was superior to that of poly(lactide-co-glycolide) in terms of proliferating cell nuclear antigen inhibition. The cell viability test using methyl thiazolyl tetrazolium revealed a similar inhibitory effect. Furthermore, the carboplatin-loaded nanoparticles of lower concentration inhibited cell viability more strongly than native carboplatin of higher concentration in methyl thiazolyl tetrazolium assay. Conclusions: Carboplatin-loaded sodium alginate-poly(lactide-co-glycolide) inhibited retinoblastoma cell proliferation with superior effect as compared with poly(lactide-co-glycolide) and native carboplatin. Sodium alginate surface modification offers a potential strategy for the sustained carboplatin release system.

RESUMO Objetivo: Investigar o efeito antiproliferativo de poli (lactídeo-coglicolídeo) com superfície modificada carregada com carboplatina contra células de retinoblastoma. Métodos: Preparou-se poli (lactídeo-co-glicolídeo) carregado com carboplatina com ou sem alginato de sódio para modifição da superfície, poli com alginato de sódio (lactídeo-co-glicolídeo) e poli (lactídeo-co-glicolídeo). O potencial zeta e o comportamento de liberação de carboplatina foram investigados. A captação celular do fármaco liberado foi observada na linha celular de retinoblastoma Y79. O efeito inibitório das nanopartículas carregadas com carboplatina contra a linha celular Y79 foi avaliado através do ensaio de metiltiazol tetrazólio e Western-blot. Carboplatina nativa e nanopartículas vazias sem carga de carboplatina serviram como controles. Resultados: O potencial zeta de poli carregado com carboplatina (lactídeo-co-glicolídeo) foi - (26,1 ± 3,1) mV versus - (43,1 ± 8,1) mV em poli com alginato de sódio carregado com carboplatina (lactídeo-co-glicolídeo). A percentagem de libertação de explosão de poli carregado com carboplatina (lactídeo-co-glicolídeo) e poli com alginato de sódio (lactídeo-co-glicolídeo) foram (40,0 ± 8,2)% e (18,9 ± 4,3)% às 24 horas, respectivamente. Uma diferença significativa foi identificada em relação à liberação de fármaco entre poli com alginato de sódio carregado com carboplatina (lactídeo-co-glicolídeo) e poli carregado com carboplatina (lactídeo-co-glicolídeo). A detecção de fluorescência revelou que a carboplatina foi assimilada intensamente no citoplasma da linha celular Y79 que foi exposta ao poli com alginato de sódio carregado com carboplatina (lactídeo-co-glicolídeo). A exposição de poli carregada com carboplatina (lactídeo-co-glicolídeo) ou poli com alginato de sódio (lactídeo-co-glicolídeo) inibiu a expressão de antígeno nuclear de proliferação celular em células Y79 no 3º dia. A extensão da exposição no 5º dia revelou que poli com alginato de sódio (lactídeo-co-glicolídeo) para modificação da superfície foi superior a poli (lactídeo-co-glicolídeo) em termos de inibição do antígeno nuclear de proliferação celular. O teste de viabilidade celular via metiltiazol tetrazólio mostrou um efeito inibitório semelhante. Além disso, as nanopartículas carregadas com carboplatina de concentração mais baixa inibiram a viabilidade celular mais fortemente em comparação com a carboplatina nativa de concentração mais alta no ensaio de metiltiazol tetrazólio. Conclusões: Poli com alginato de sódio carregado com carboplatina (lactídeo-co-glicolídeo) inibiu a proliferação de células de retinoblastoma com efeito superior em contraste com poli (lactídeo-co-glicolídeo) e carboplatina nativa. O alginato de sódio para modificação da superfície oferece uma estratégia potencial para o sistema de liberação de carboplatina sustentada.

Novel mutations in HTRA1-related cerebral small vessel disease and comparison with CADASIL.

OBJECTIVE: There is evidence showing both heterozygous HTRA1 and homozygous HTRA1 mutations as causal for familial cerebral small vessel disease (CSVD). The clinical and neuroimaging signs of heterozygous HTRA1-related CSVD can mimic cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). We aimed to characterize the genotypic and phenotypic features of HTRA1-related CSVD, and we compared the features of heterozygous HTRA1-related CSVD and CADASIL. METHODS: We carried out genetic sequencing in a series of unrelated patients with suspected familial CSVD from China. Clinical and imaging characteristics of heterozygous HTRA1-related CSVD and CADASIL were compared. RESULTS: We identified nine heterozygous HTRA1 mutations and one homozygous HTRA1 mutation, seven of which are novel. Compared with CADASIL, patients with heterozygous HTRA1-related CSVD had a higher proportion of spine disorders and a lower proportion of white matter hyperintensities involving the anterior temporal lobe (p < 0.001). INTERPRETATION: This study shows that most HTRA1-related CSVD patients in China carry heterozygous HTRA1 mutations. The specific extra-neurological features and neuroimaging features reveal informative differences between heterozygous HTRA1-related CSVD and CADASIL. We expand the mutational spectrum of HTRA1.

Carboplatin-loaded surface modified-PLGA nanoparticles confer sustained inhibitory effect against retinoblastoma cell in vitro.

PURPOSE: To investigate the antiproliferative effect of carboplatin-loaded surface-modified poly(lactide-co-glycolide) on retinoblastoma cells. METHODS: Carboplatin-loaded poly(lactide-co-glycolide) with or without sodium alginate surface modification was prepared using sodium alginate-poly(lactide-co-glycolide) and poly(lactide-co-glycolide). The zeta potential and carboplatin release behavior were investigated. The cellular uptake of the released drug was observed in the retinoblastoma cell line Y79. The inhibitory effect of carboplatin-loaded nanoparticles against the Y79 cell line was evaluated using methyl thiazolyl tetrazolium assay and western blot. Native carboplatin and void nanoparticles without carboplatin loading were used as controls. RESULTS: The zeta potential was -(26.1 ± 3.1) mV for carboplatin-loaded poly(lactide-co-glycolide) and-(43.1 ± 8.1) mV for carboplatin-loaded sodium alginate-poly(lactide-co-glycolide). The burst release percentages of carboplatin-loaded poly(lactide-co-glycolide) and sodium alginate-poly(lactide-co-glycolide) were (40.0% ± 8.2%) and (18.9% ± 4.3%) at 24 hours, respectively. A significant difference was identified regarding drug release between carboplatin-loaded sodium alginate-poly(lactide-co-glycolide) and carboplatin-loaded poly(lactide-co-glycolide). Fluorescence detection revealed that intense uptake of carboplatin into the cytoplasm of the Y79 cell line that was exposed to carboplatin-loaded sodium alginate-poly(lactide-co-glycolide). Carboplatin-loaded poly(lactide-co-glycolide) or sodium alginate-poly(lactide-co-glycolide) exposure inhibited proliferating cell nuclear antigen expression in Y79 cells on day 3. Extension of exposure to day 5 revealed that the sodium alginate-poly(lactide-co-glycolide) surface modification was superior to that of poly(lactide-co-glycolide) in terms of proliferating cell nuclear antigen inhibition. The cell viability test using methyl thiazolyl tetrazolium revealed a similar inhibitory effect. Furthermore, the carboplatin-loaded nanoparticles of lower concentration inhibited cell viability more strongly than native carboplatin of higher concentration in methyl thiazolyl tetrazolium assay. CONCLUSIONS: Carboplatin-loaded sodium alginate-poly(lactide-co-glycolide) inhibited retinoblastoma cell proliferation with superior effect as compared with poly(lactide-co-glycolide) and native carboplatin. Sodium alginate surface modification offers a potential strategy for the sustained carboplatin release system.

Insights Into the Role of CSF1R in the Central Nervous System and Neurological Disorders.

The colony-stimulating factor 1 receptor (CSF1R) is a key tyrosine kinase transmembrane receptor modulating microglial homeostasis, neurogenesis, and neuronal survival in the central nervous system (CNS). CSF1R, which can be proteolytically cleaved into a soluble ectodomain and an intracellular protein fragment, supports the survival of myeloid cells upon activation by two ligands, colony stimulating factor 1 and interleukin 34. CSF1R loss-of-function mutations are the major cause of adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) and its dysfunction has also been implicated in other neurodegenerative disorders including Alzheimer's disease (AD). Here, we review the physiological functions of CSF1R in the CNS and its pathological effects in neurological disorders including ALSP, AD, frontotemporal dementia and multiple sclerosis. Understanding the pathophysiology of CSF1R is critical for developing targeted therapies for related neurological diseases.

A Novel CNTNAP2 Mutation Results in Abnormal Neuronal E/I Balance.

CNTNAP2 (coding for protein Caspr2), a member of the neurexin family, plays an important role in the balance of excitatory and inhibitory post-synaptic currents (E/I balance). Here, we describe a novel pathogenic missense mutation in an infant with spontaneous recurrent seizures (SRSs) and intellectual disability. Genetic testing revealed a missense mutation, c.2329 C>G (p. R777G), in the CNTNAP2 gene. To explore the effect of this novel mutation, primary cultured neurons were transfected with wild type homo CNTNAP2 or R777G mutation and the morphology and function of neurons were evaluated. When compared with the vehicle control group or wild type group, the neurites and the membrane currents, including spontaneous excitatory post-synaptic currents (sEPSCs) and inhibitory post-synaptic currents (sIPSCs), in CNTNAP2 R777G mutation group were all decreased or weakened. Moreover, the action potentials (APs) were also impaired in CNTNAP2 R777G group. Therefore, CNTNAP2 R777G may lead to the imbalance of excitatory and inhibitory post-synaptic currents in neural network contributing to SRSs.

Triggering Receptor Expressed on Myeloid Cells-2 (TREM2) Interacts With Colony-Stimulating Factor 1 Receptor (CSF1R) but Is Not Necessary for CSF1/CSF1R-Mediated Microglial Survival.

Triggering receptor expressed on myeloid cells-2 (TREM2) and colony-stimulating factor 1 receptor (CSF1R) are crucial molecules for microgliopathy, which is characterized by microglia dysfunction and has recently been proposed as the neuropathological hallmark of neurological disorders. TREM2 and CSF1R are receptors expressed primarily in microglia in the brain and modulate microglial activation and survival. They are thought to be in close physical proximity. However, whether there is a direct interaction between these receptors remains elusive. Moreover, the physiological role and mechanism of the interaction of TREM2 and CSF1R remain to be determined. Here, we found that TREM2 interacted with CSF1R based on a co-immunoprecipitation assay. Additionally, we found that CSF1R knockdown significantly reduced the survival of primary microglia and increased the Trem2 mRNA level. In contrast, CSF1R expression was increased in Trem2-deficient microglia. Interestingly, administration of CSF1, the ligand of CSF1R, partially restored the survival of Trem2-deficient microglia in vitro and in vivo. Furthermore, CSF1 ameliorated Aß plaques deposition in Trem2-/-; 5XFAD mouse brain. These findings provide solid evidence that TREM2 and CSF1R have intrinsic abilities to form complexes and mutually modulate their expression. These findings also indicate the potential role of CSF1 in therapeutic intervention in TREM2 variant-bearing patients with a high risk of Alzheimer's disease (AD).

Proteolytic Shedding of Human Colony-Stimulating Factor 1 Receptor and its implication.

Both Colony-stimulating factor 1 receptor (CSF1R) and triggering receptor expressed on myeloid cells-2 (TREM2) are trans-membrane receptors and are expressed in the brain primarily by microglia. Mutations in these two microglia-expressed genes associated with neurodegenerative disease have recently been grouped under the term "microgliopathy". Several literatures have indicated that CSF1R and TREM2 encounters a stepwise shedding and TREM2 variants impair or accelerate the processing. However, whether CSF1R variant affects the shedding of CSF1R remains elusive. Here, plasmids containing human CSF1R or TREM2 were transiently transfected into the human embryonic kidney (HEK) 293T cells. Using Western Blot and/or ELISA assay, we demonstrated that, similar to those of TREM2, an N-terminal fragment (NTF) shedding of CSF1R ectodomain and a subsequent C-terminal fragment (CTF) of CSF1R intra-membrane were generated by a disintegrin and metalloprotease (ADAM) family member and by γ-secretase, respectively. And the shedding was inhibited by treatment with Batimastat, an ADAM inhibitor, or DAPT or compound E, a γ-secretase inhibitor. Importantly, we show that the cleaved fragments, both extracellular domain and intracellular domain of a common disease associated I794T variant, were decreased significantly. Together, our studies demonstrate a stepwise approach of human CSF1R cleavage and contribute to understand the pathogenicity of CSF1R I794T variant in adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP). These studies also suggest that the cleaved ectodomain fragment released from CSF1R may be proposed as a diagnostic biomarker for ALSP.

TMEM59 interacts with TREM2 and modulates TREM2-dependent microglial activities.

The surface receptor triggering receptor expressed on myeloid cells 2 (TREM2) plays a crucial role in maintaining a multitude of microglial activities, such as survival, proliferation, migration, metabolism, inflammation, and phagocytosis. However, the molecular mechanisms underlying TREM2-mediated microglial activities remain largely elusive. Herein, we found that TREM2 interacted with the type I transmembrane protein TMEM59, whose expression could facilitate autophagic flux through its carboxyl-terminus. TMEM59 expression was decreased upon lipopolysaccharide treatment. While downregulation of TMEM59 promoted anti-inflammatory factor expression and attenuated lipopolysaccharide treatment-induced inflammation. Importantly, we found that overexpression of TREM2 reduced TMEM59 protein levels through promoting its degradation, whereas TMEM59 levels were elevated in Trem2-deficient microglia. Finally, impaired survival, proliferation, migration, and phagocytosis, as well as dysregulated autophagy and metabolism in Trem2-deficient microglia were attenuated upon TMEM59 silencing. Together, our findings reveal a novel function of TREM2 in mediating TMEM59 protein degradation and demonstrate the importance of TMEM59 homeostasis in maintaining TREM2-mediated microglial activities.

Activation of FAK/Rac1/Cdc42-GTPase signaling ameliorates impaired microglial migration response to Aß42 in triggering receptor expressed on myeloid cells 2 loss-of-function murine models.

Mutation of Triggering receptor expressed on myeloid cells 2 (TREM2) impairs the response of microglia to amyloid-ß (Aß) pathology in Alzheimer's disease (AD), although the mechanism governing TREM2-regulated microglia recruitment to Aß plaques remains unresolved. Here, we confirm that TREM2 mutation attenuates microglial migration. Then, using Trem2-/- mice and an R47H variant mouse model for AD generated for this study, we show that TREM2 deficiency or the AD-associated R47H mutation results in inhibition of FAK and Rac1/Cdc42-GTPase signaling critical for cell migration. Intriguingly, treatment with CN04, a Rac1/Cdc42-GTPase activator, partially enhances microglial migration in response to oligomeric Aß42 in Trem2-/- or R47H microglia both in vitro and in vivo. Our study shows that the dysfunction of microglial migration in the AD-associated TREM2 R47H variant is caused by FAK/Rac1/Cdc42 signaling disruption, and that activation of this signaling ameliorates impaired microglial migration response to Aß42 , suggesting a therapeutic target for R47H-bearing patients with high risk of AD.

Cortical Damage Associated With Cognitive and Motor Impairment in Hereditary Spastic Paraplegia: Evidence of a Novel SPAST Mutation.

To determine the cortical mechanism that underlies the cognitive impairment and motor disability in hereditary spastic paraplegia (HSP), nine HSP patients from a Chinese family were examined using clinical evaluation, cognitive screening, and genetic testing. Controls were matched healthy subjects. White-matter fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD; tract-based spatial statistics), cortical thickness (FreeSurfer), and subcortical gray matter (FIRST) based on T1-weighted MRI and diffusion tensor imaging were analyzed. A novel mutation in the SPAST gene (NM_014946.3, c.1321+2T>C) was detected. Patients had motor disability and low Montreal Cognitive Assessment (MoCA) scores. Patients showed significantly decreased total gray- and white-matter volumes, corpus callosum volume, cortical thickness, and subcortical gray-matter volume as well as significantly lower FA and AD values and significantly higher MD and RD values in the corpus callosum and corticospinal tract. Cortical thickness, subcortical gray-matter volume, and MoCA score were negatively correlated with disease duration. Cortical thickness in the right inferior frontal cortex was negatively correlated with Spastic Paraplegia Rating Scale score. Cortical thickness and right hippocampus volume were positively correlated with the MoCA score and subscores. In conclusion, brain damage is not restricted to the white matter in SPG4-HSP patients, and widespread gray-matter damage may account for the disease progression, cognitive impairment, and disease severity in SPG4-HSP.

ErbB4 Mutation that Decreased NRG1-ErbB4 Signaling Involved in the Pathogenesis of Amyotrophic Lateral Sclerosis/Frontotemporal Dementia.

BACKGROUND: Amyotrophic lateral sclerosis/frontotemporal dementia (ALS/FTD) includes a large spectrum of neurodegenerative disorders. OBJECTIVE: To identify the relationship of ErbB4 mutation and ALS/FTD. METHODS: Here, we report an atypical case of frontal variant behavioral abnormalities at the initial stage, a stable plateau stage of 5 years, and paralysis involving both upper and lower motor neurons followed by progressive cognitive dysfunction at the advanced stage. The clinical findings suggested a diagnosis of ALS/FTD, and genetic testing revealed erb-b2 receptor tyrosine kinase 4 (ErbB4) heterozygous mutation (c.2136 T>G, p.I712M), identified in an ALS pedigree previously. We modeled mutant ErbB4 protein through the SWISS-MODEL Server, and speculated on the structural change caused by the mutation. We also identified that ErbB4 (I712M) mutation led to reduced auto-phosphorylation of ErbB4 upon neuregulin-1 (NRG1) stimulation. RESULTS: A functional analysis of ErbB4 mutation demonstrated an obviously decreased auto-phosphorylation of ErbB4 involving in the pathogenesis of ALS/FTD. CONCLUSION: We firstly found ErbB4 mutation to be identified in ALS/FTD.

A brain somatic RHEB doublet mutation causes focal cortical dysplasia type II.

Focal cortical dysplasia type II (FCDII) is a cerebral cortex malformation characterized by local cortical structure disorganization, neuronal dysmorphology, and refractory epilepsy. Brain somatic mutations in several genes involved in the PI3K/AKT/mTOR pathway are associated with FCDII, but they are only found in a proportion of patients with FCDII. The genetic causes underlying the development FCDII in other patients remain unclear. Here, we carried out whole exome sequencing and targeted sequencing in paired brain-blood DNA from patients with FCDII and identified a brain somatic doublet mutation c.(A104T, C105A) in the Ras homolog, mTORC1 binding (RHEB) gene, which led to the RHEB p.Y35L mutation in one patient with FCDII. This RHEB mutation carrier had a dramatic increase of ribosomal protein S6 phosphorylation, indicating mTOR activation in the region of the brain lesion. The RHEB p.Y35L mutant protein had increased GTPλS-binding activity compared with wild-type RHEB. Overexpression of the RHEB p.Y35L variant in cultured cells also resulted in elevated S6 phosphorylation compared to wild-type RHEB. Importantly, in utero electroporation of the RHEB p.Y35L variant in mice induced S6 phosphorylation, cytomegalic neurons, dysregulated neuron migration, abnormal electroencephalogram, and seizures, all of which are found in patients with FCDII. Rapamycin treatment rescued abnormal electroencephalograms and alleviated seizures in these mice. These results demonstrate that brain somatic mutations in RHEB are also responsible for the pathogenesis of FCDII, indicating that aberrant activation of mTOR signaling is a primary driver and potential drug target for FCDII.

Silencing MicroRNA-155 Attenuates Kainic Acid-Induced Seizure by Inhibiting Microglia Activation.

OBJECTIVE(S): Neuroinflammation is an important contributor to the development of seizures and epilepsy. Micro-RNA-155 (miR-155) plays a critical role in immunity and -inflammation. This study aims to explore the function of miR-155 and miR-155-mediated inflammation in epilepsy. METHODS: About 8-week-old male C57BL/6 mice were administered an intraperitoneal injection (i.p.) of kainic acid (KA) (15 mg/kg) or saline. The mice in the KA group developing acute seizure were further subjected to intracerebroventricular injection (i.c.v.) of antagomir negative control (NC) or miR-155 antagomir. Animal behavior was observed according to Racine's scale, and electroencephalographs were recorded. Primary microglia were cultured and treated with antagomir NC or antagomir. Whole-cell electrophysiological recording was conducted to detect the spontaneous EPSCs and IPSCs in the neurons treated with different conditioned medium from those microglia. miR-155 were detected by qRT-PCR in those models, as well as in the brain or blood from epileptic patients and healthy controls. RESULTS: miR-155 was abundantly expressed in glial cells compared with neurons, and its expression was markedly elevated in the brain of epilepsy patients and KA-induced seizure mice. Silencing miR-155 attenuated KA-induced seizure, abnormal electroencephalography, proinflammatory cytokine expression, and microglia morphology change. Moreover, conditioned media from KA-treated microglia impaired neuron excitability, whereas conditioned media from KA and miR-155 antagomir co-treated microglia had no such effects. Finally, miR-155 levels were significantly higher in the blood of epilepsy patients than those of healthy controls. CONCLUSION(S): These findings demonstrate that aberrant upregulation of miR-155 contributes to epileptogenesis through inducing microglia neuroinflammation.

TREM2 in Alzheimer's Disease: Microglial Survival and Energy Metabolism.

Alzheimer's disease (AD) is the leading cause of age-related dementia among the elderly population. Recent genetic studies have identified rare variants of the gene encoding the triggering receptor expressed on myeloid cells-2 (TREM2) as significant genetic risk factors in late-onset AD (LOAD). TREM2 is specifically expressed in brain microglia and modulates microglial functions in response to key AD pathologies such as amyloid-ß (Aß) plaques and tau tangles. In this review article, we discuss recent research progress in our understanding on the role of TREM2 in microglia and its relevance to AD pathologies. In addition, we discuss evidence describing new TREM2 ligands and the role of TREM2 signaling in microglial survival and energy metabolism. A comprehensive understanding of TREM2 function in the pathogenesis of AD offers a unique opportunity to explore the potential of this microglial receptor as an alternative target in AD therapy.

Protective Role of L-3-n-Butylphthalide in Cognitive Function and Dysthymic Disorders in Mouse With Chronic Epilepsy.

Epilepsy is a common neurological disease with recurrent seizures and neurobehavioral comorbidities, including cognitive impairment and psychiatric disorders. Recent studies suggest that L-3-n-butylphthalide (NBP), an extract from the seeds of Apium graveolens Linn. (Chinese celery), ameliorates cognitive dysfunction in ischemia and/or Alzheimer's disease animal models. However, little is known about the role of NBP in epilepsy and the associated comorbidities. Here, using a pilocarpine-induced chronic epileptic mouse model, we found that NBP supplement not only alleviated seizure severity and abnormal electroencephalogram, but also rescued cognitive and emotional impairments in these epileptic mice. The possible underlying mechanisms may be associated with the protective role of NBP in reducing neuronal loss and in restoring the expression of neural synaptic proteins such as postsynaptic density protein 95 (PSD95) and glutamic acid decarboxylase 65/67 (GAD65/67). In addition, NBP treatment increased the transcription of neuroprotective factors, brain-derived neurotrophic factor and Klotho. These findings suggest that NBP treatment may be a potential strategy for ameliorating epileptogenesis and the comorbidities of cognitive and psychological impairments.