First Case of Peroxisomal D-bifunctional Protein Deficiency with Novel HSD17B4 Mutations and Progressive Neuropathy in Korea.

Peroxisomal D-bifunctional protein (DBP), encoded by the HSD17B4 gene, catalyzes ß-oxidation of very long chain fatty acids (VLCFAs). The deficiency of this peroxisomal enzyme leads to the accumulation of VLCFAs, causing multisystemic manifestations including the brain, retina, adrenal gland, hearing, and skeletal system. Herein, we report the first Korean neonatal case of peroxisomal DBP deficiency and the clinical prognosis over 2 years. This patient showed craniofacial dysmorphism, club foot, and seizures with cyanosis one day after birth. Elevated VLCFAs levels were indicative of a peroxisomal disorder. Targeted exome sequencing was performed and two missense mutations p.Asp117Val and p.Phe279Ser in the HSD17B4 gene were identified. The patient had type III DBP deficiency; therefore, docosahexaenoic acid and non-soluble vitamins were administered. However, progressive nystagmus, optic nerve atrophy, and bilateral hearing defects were observed and follow-up brain imaging revealed leukodystrophy and brain atrophy. Multiple anti-epileptic drugs were required to control the seizures. Over two years, the patient achieved normal growth with home ventilation and tube feeding. Hereby, the subject's parents had support during the second pregnancy from the proven molecular information. Moreover, targeted exome sequencing is an effective diagnostic approach, considering genetic heterogeneity of Zellweger spectrum disorders.

Peptide-mediated targeted delivery of SOX9 nanoparticles into astrocytes ameliorates ischemic brain injury.

Astrocytes are highly activated following brain injuries, and their activation influences neuronal survival. Additionally, SOX9 expression is known to increase in reactive astrocytes. However, the role of SOX9 in activated astrocytes following ischemic brain damage has not been clearly elucidated yet. Therefore, in the present study, we investigated the role of SOX9 in reactive astrocytes using a poly-lactic-co-glycolic acid (PLGA) nanoparticle plasmid delivery system in a photothrombotic stroke animal model. We designed PLGA nanoparticles to exclusively enhance SOX9 gene expression in glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes. Our observations indicate that PLGA nanoparticles encapsulated with GFAP:SOX9:tdTOM reduce ischemia-induced neurological deficits and infarct volume through the prostaglandin D2 pathway. Thus, the astrocyte-targeting PLGA nanoparticle plasmid delivery system provides a potential opportunity for stroke treatment. Since the only effective treatment currently available is reinstating the blood supply, cell-specific gene therapy using PLGA nanoparticles will open a new therapeutic paradigm for brain injury patients in the future.

p66shc siRNA-Encapsulated PLGA Nanoparticles Ameliorate Neuropathic Pain Following Spinal Nerve Ligation.

p66shc, a member of the shc adaptor protein family, has been shown to participate in regulation of mitochondrial homeostasis, apoptosis, and autophagosome formation. The present study was performed to investigate whether p66shc siRNA-encapsulated poly(d,l-lactic-co-glycolic acid) nanoparticles (p66shc siRNA-PLGA NPs) can attenuate spinal nerve ligation (SNL)-induced neuropathic pain in rats. The SNL-induced pain behavior was decreased in the p66shc siRNA-PLGA NP-treated group compared with the scrambled siRNA-PLGA NP-treated group. In the L5 spinal cord of the p66shc siRNA-PLGA NP-treated group, expression levels of phosphorylated p66shc, cleaved caspase-3, p62, and PINK1, as well as microglial activation, were also decreased. In addition, p66shc knockdown using p66shc siRNA reduced the expression levels of cleaved caspase-3, p62, and PINK1, as well as proinflammatory mediators in the H2O2-treated HT22 neuronal cells. These results suggest that downregulation of p66shc expression in the spinal cord using p66shc siRNA-PLGA NPs could reduce the SNL-induced neuropathic pain by attenuating the SNL-induced aberrant autophagic, mitophagic, and neuroinflammatory processes in rats.

Calpain-2 as a Treatment Target in Prenatal Stress-induced Epileptic Spasms in Infant Rats.

Stress can induce a serious epileptic encephalopathy that occurs during early infancy. Recent studies have revealed that prenatal stress exposure is a risk factor for the development of infantile spasms. Our previous work demonstrates that prenatal stress with betamethasone-induced alterations to the expression of the K+/Cl- co-transporter (KCC2) in gamma-aminobutyric acid (GABA) interneurons lowers the seizure threshold in exposed animals. Here, we further investigated the mechanisms involved in this KCC2 dysfunction and explored possible treatment options. We stressed Sprague-Dawley rats prenatally and further treated dams with betamethasone on gestational day 15, which increases seizure susceptibility and NMDA (N-Methyl-D-aspartate)-triggered spasms on postnatal day 15. In this animal model, first, we evaluated baseline calpain activity. Second, we examined the cleavage and dephosphorylation of KCC2. Finally, we checked the effect of a calpain inhibitor on seizure occurrence. The phosphorylated-N-methyl-Daspartate Receptor 2B (NR2B):non-phosphorylated NR2B ratio was found to be higher in the cortex of the prenatally stressed betamethasone model. We further found that the betamethasone model exhibited increased phosphorylation of calpain-2 and decreased phosphorylation of KCC2 and Glutamic acid decarboxylase 67 (GAD67). After using a calpain inhibitor in prenatal-stress rats, the seizure frequency decreased, while latency increased. GABAergic depolarization was further normalized in prenatal-stress rats treated with the calpain inhibitor. Our study suggests that calpain-dependent cleavage and dephosphorylation of KCC2 decreased the seizure threshold of rats under prenatal stress. Calpain-2 functions might, thus, be targeted in the future for the development of treatments for epileptic spasms.

Central Nervous System and its Disease Models on a Chip.

Technologies for microfluidics and biological microelectromechanical systems have been rapidly progressing over the past decade, enabling the development of unique microplatforms for in vitro human central nervous system (CNS) and related disease models. Most fundamental techniques include manipulation of axons, synapses, and neuronal networks, and different culture conditions are possible, such as compartmental, co-culturing, and 3D. Various CNS disease models, such as Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), epilepsy, N-methyl-D-aspartate receptor (NMDAR) encephalitis, migraine, diffuse axonal injury, and neuronal migration disorders, have been successfully established on microplatforms. In this review, we summarize fundamental technologies and current existing CNS disease models on microplatforms. We also discuss possible future directions, including application of these methods to pathological studies, drug screening, and personalized medicine, with 3D and personalized disease models that could generate more realistic CNS disease models.