Pericytes in Alzheimer's disease: Key players and therapeutic targets.

Alzheimer's disease (AD) is a devastating neurodegenerative disorder that leads to progressive cognitive decline and neuropathological changes. Pericytes, which are vessel mural cells on the basement membrane of capillaries, play a crucial role in regulating cerebrovascular functions and maintaining neurovascular unit integrity. Emerging research substantiates the involvement of pericytes in AD. This review provides a comprehensive overview of pericytes, including their structure, origin, and markers and various functions within the central nervous system. Emphatically, the review explores the intricate mechanisms through which pericytes contribute to AD, including their interactions with amyloid beta and apolipoprotein E, as well as various signaling pathways. The review also highlights potential for targeted pericyte therapy for AD, with a focus on stem cell therapy and drug treatments. Future research directions include the classification of pericyte subtypes, studies related to aging, and the role of pericytes in exosome-related mechanisms in AD pathology. In conclusion, this review consolidates current knowledge on the pivotal roles of pericytes in AD and their potential as therapeutic targets, providing valuable insights for future research and clinical interventions aimed at addressing the impact of AD on patients' lives.

Targeting mitophagy for neurological disorders treatment: advances in drugs and non-drug approaches.

Mitochondria serve as a vital energy source for nerve cells. The mitochondrial network also acts as a defense mechanism against external stressors that can threaten the stability of the nervous system. However, excessive accumulation of damaged mitochondria can lead to neuronal death. Mitophagy is an essential pathway in the mitochondrial quality control system and can protect neurons by selectively removing damaged mitochondria. In most neurological disorders, dysfunctional mitochondria are a common feature, and drugs that target mitophagy can improve symptoms. Here, we reviewed the role of mitophagy in Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, Huntington's disease, stroke, and traumatic brain injuries. We also summarized drug and non-drug approaches to promote mitophagy and described their therapeutic role in neurological disorders in order to provide valuable insight into the potential therapeutic agents available for neurological disease treatment. However, most studies on mitophagy regulation are based on preclinical research using cell and animal models, which may not accurately reflect the effects in humans. This poses a challenge to the clinical application of drugs targeting mitophagy. Additionally, these drugs may carry the risk of intolerable side effects and toxicity. Future research should focus on the development of safer and more targeted drugs for mitophagy.

Identification of core genes in prefrontal cortex and hippocampus of Alzheimer's disease based on mRNA-miRNA network.

Alzheimer's disease (AD) is a neurodegenerative disorder with cognitive impairment and abnormal mental behaviour. There is currently no effective cure. The development of early diagnostic markers and the mining of potential therapeutic targets are one of the important strategies. This study aimed to explore potential biomarkers or therapeutic targets related to AD in the hippocampus and prefrontal cortex, two brain regions highly related to AD. Differentially expressed genes and miRNAs between AD patients and healthy controls were obtained from the Gene Expression Omnibus database. The mRNA-miRNA network was constructed and key genes involved in AD were screened out by protein-protein interaction analysis, and were subsequently verified by independent datasets and qPCR in an AD mouse model. Our findings showed that six hub genes including CALN1, TRPM7, ATR, SOCS3, MOB3A and OGDH were believed to be involved in the pathogenesis of AD. Western blot analysis further determined that CALN1, ATR and OGDH were the possible biomarkers and therapeutic targets for AD. In addition, 6 possible miRNAs biomarkers have also been verified by qPCR on AD animal models. Our findings may benefit clinical diagnosis and early prevention of AD.

Role of the hydrogen sulfide-releasing donor ADT-OH in the regulation of mammal neural precursor cells.

Neural precursor cells (NPCs) generate new neurons to supplement neuronal loss as well as to repair damaged neural circuits. Therefore, NPCs have potential applications in a variety of neurological diseases, such as spinal cord injury, traumatic brain injury, and glaucoma. Specifically, improving NPCs proliferation and manipulating their differentiated cell types can be a beneficial therapy for a variety of these diseases. ADT-OH is a slow-releasing organic H2 S donor that produces a slow and continuous release of H2 S to maintain normal brain functions. In this study, we aimed to explore the effect of ADT-OH on NPCs. Our results demonstrated that ADT-OH promotes self-renewal and antiapoptosis ability of cultured NPCs. Additionally, it facilitates more NPCs to differentiate into neurons and oligodendrocytes, while inhibiting their differentiation into astrocytes. Furthermore, it enhances axonal growth. Moreover, we discovered that the mRNA and protein expression of ß-catenin, TCF7L2, c-Myc, Ngn1, and Ngn2, which are key genes that regulate NPCs self-renewal and differentiation, were increased in the presence of ADT-OH. Altogether, these results indicate that ADT-OH may be a promising drug to regulate the neurogenesis of NPCs, and needs to be studied in the future for clinical application potential.

Clemastine attenuates AD-like pathology in an AD model mouse via enhancing mTOR-mediated autophagy.

Alzheimer's disease (AD) is a neurodegenerative disorder with limited available drugs for treatment. Enhancing autophagy attenuates AD pathology in various AD model mice. Thus, development of potential drugs which enhance autophagy may bring beneficial effects in AD therapy. In the present study, we show clemastine, a first-generation histamine H1R antagonist and being originally marketed for the treatment of allergic rhinitis, ameliorates AD pathogenesis in APP/PS1 transgenic mice. Chronic treatment with clemastine orally reduced amyloid-ß (Aß) load, neuroinflammation and cognitive deficits of APP/PS1 transgenic mice. Clemastine decreases Aß generation via reducing the levels of BACE1, CTFs of APP. Mechanistically, clemastine enhances autophagy concomitant with a suppression of mTOR signaling. Therefore, we propose that clemastine attenuates AD pathology via enhancing mTOR-mediated autophagy.

Intranasal Transplantation of Human Neural Stem Cells Ameliorates Alzheimer's Disease-Like Pathology in a Mouse Model.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by memory impairments, which has no effective therapy. Stem cell transplantation shows great potential in the therapy of various disease. However, the application of stem cell therapy in neurological disorders, especially the ones with a long-term disease course such as AD, is limited by the delivery approach due to the presence of the brain blood barrier. So far, the most commonly used delivery approach in the therapy of neurological disorders with stem cells in preclinical and clinical studies are intracranial injection and intrathecal injection, both of which are invasive. In the present study, we use repetitive intranasal delivery of human neural stem cells (hNSCs) to the brains of APP/PS1 transgenic mice to investigate the effect of hNSCs on the pathology of AD. The results indicate that the intranasally transplanted hNSCs survive and exhibit extensive migration and higher neuronal differentiation, with a relatively limited glial differentiation. A proportion of intranasally transplanted hNSCs differentiate to cholinergic neurons, which rescue cholinergic dysfunction in APP/PS1 mice. In addition, intranasal transplantation of hNSCs attenuates ß-amyloid accumulation by upregulating the expression of ß-amyloid degrading enzymes, insulin-degrading enzymes, and neprilysin. Moreover, intranasal transplantation of hNSCs ameliorates other AD-like pathology including neuroinflammation, cholinergic dysfunction, and pericytic and synaptic loss, while enhancing adult hippocampal neurogenesis, eventually rescuing the cognitive deficits of APP/PS1 transgenic mice. Thus, our findings highlight that intranasal transplantation of hNSCs benefits cognition through multiple mechanisms, and exhibit the great potential of intranasal administration of stem cells as a non-invasive therapeutic strategy for AD.

Transplantation of GABAergic Interneuron Progenitor Attenuates Cognitive Deficits of Alzheimer's Disease Model Mice.

Excitatory (E) and inhibitory (I) balance of neural network activity is essential for normal brain function and of particular importance to memory. Disturbance of E/I balance contributes to various neurological disorders. The appearance of neural hyperexcitability in Alzheimer's disease (AD) is even suggested as one of predictors of accelerated cognitive decline. In this study, we found that GAD67+, Parvalbumin+, Calretinin+, and Neuropeptide Y+ interneurons were progressively lost in the brain of APP/PS1 mice. Transplanted embryonic medial ganglionic eminence derived interneuron progenitors (IPs) survived, migrated, and differentiated into GABAergic interneuron subtypes successfully at 2 months after transplantation. Transplantation of IPs hippocampally rescued impaired synaptic plasticity and cognitive deficits of APP/PS1 transgenic mice, concomitant with a suppression of neural hyperexcitability, whereas transplantation of IPs failed to attenuate amyloid-ß accumulation, neuroinflammation, and synaptic loss of APP/PS1 transgenic mice. These observations indicate that transplantation of IPs improves learning and memory of APP/PS1 transgenic mice via suppressing neural hyperexcitability. This study highlights a causal contribution of GABAergic dysfunction to AD pathogenesis and the potentiality of IP transplantation in AD therapy.

Mitochondrial Dysfunction in Neural Injury.

Mitochondria are the double membrane organelles providing most of the energy for cells. In addition, mitochondria also play essential roles in various cellular biological processes such as calcium signaling, apoptosis, ROS generation, cell growth, and cell cycle. Mitochondrial dysfunction is observed in various neurological disorders which harbor acute and chronic neural injury such as neurodegenerative diseases and ischemia, hypoxia-induced brain injury. In this review, we describe how mitochondrial dysfunction contributes to the pathogenesis of neurological disorders which manifest chronic or acute neural injury.

Disrupted-in-schizophrenia-1 protects synaptic plasticity in a transgenic mouse model of Alzheimer's disease as a mitophagy receptor.

Mitochondrial dysfunction is an early feature of Alzheimer's disease (AD). Accumulated damaged mitochondria, which are associated with impaired mitophagy, contribute to neurodegeneration in AD. We show levels of Disrupted-in-schizophrenia-1 (DISC1), which is genetically associated with psychiatric disorders and AD, decrease in the brains of AD patients and transgenic model mice and in Aß-treated cultured cells. Disrupted-in-schizophrenia-1 contains a canonical LC3-interacting region (LIR) motif (210 FSFI213 ), through which DISC1 directly binds to LC3-I/II. Overexpression of DISC1 enhances mitophagy through its binding to LC3, whereas knocking-down of DISC1 blocks Aß-induced mitophagy. We further observe overexpression of DISC1, but not its mutant (muFSFI) which abolishes the interaction of DISC1 with LC3, rescues Aß-induced mitochondrial dysfunction, loss of spines, suppressed long-term potentiation (LTP). Overexpression of DISC1 via adeno-associated virus (serotype 8, AAV8) in the hippocampus of 8-month-old APP/PS1 transgenic mice for 4 months rescues cognitive deficits, synaptic loss, and Aß plaque accumulation, in a way dependent on the interaction of DISC1 with LC3. These results indicate that DISC1 is a novel mitophagy receptor, which protects synaptic plasticity from Aß accumulation-induced toxicity through promoting mitophagy.

Inhibition of sphingomyelin synthase 1 ameliorates alzheimer-like pathology in APP/PS1 transgenic mice through promoting lysosomal degradation of BACE1.

Sphingolipids emerge as essential modulators in the etiology of Alzheimer's disease (AD) with unclear mechanisms. Elevated levels of SM synthase 1 (SMS1), which catalyzes the synthesis of SM from ceramide and phosphatidylcholine, have been observed in the brains of Alzheimer's disease (AD), where expression of ß-site APP cleaving enzyme 1 (BACE1), a rate limiting enzyme in amyloid-ß (Aß) generation, are upregulated. In the present study, we show knockdown of SMS1 via andeno associated virus (serotype 8, AAV8) in the hippocampus of APP/PS1 transgenic mice, attenuates the densities of Aß plaques, neuroinflammation, synaptic loss and thus rescuing cognitive deficits of these transgenic mice. We further describe that knockdown or inhibition of SMS1 decreases BACE1 stability, which is accompanied with decreased BACE1 levels in the Golgi, whereas enhanced BACE1 levels in the early endosomes and the lysosomes. The reduction of BACE1 levels induced by knockdown or inhibition of SMS1 is prevented by inhibition of lysosomes. Therefore, knockdown or inhibition of SMS1 promotes lysosomal degradation of BACE1 via modulating the intracellular trafficking of BACE1. Knockdown of SMS1 attenuates AD-like pathology through promoting lysosomal degradation of BACE1.

A novel role of the antitumor agent tricyclodecan-9-yl-xanthogenate as an open channel blocker of KCNQ1/KCNE1.

Tricyclodecan-9-yl-xanthogenate (D609) is widely known for its antitumor and antiviral properties via the inhibition of phosphatidylcholine-specific phospholipase C and sphingomyelin synthase. Previously, we found that chronic application of D609 suppressed the K+ channel, KCNQ1/KCNE1, more drastically than expected from its actions on the enzymes, suggesting a direct action of D609 on the channel. Here, we aimed to test this possibility by studying the affinity, specificity, and mechanisms of D609 on KCNQ1/KCNE1. The effect of D609 on KCNQ1/KCNE1 was studied using an in vitro expression system and in native cells, using electrophysiological techniques. We found that D609 rapidly and reversibly inhibited KCNQ1/KCNE1 channels expressed in human embryonic kidney 293 T (HEK293T) cells, in a concentration-dependent manner with a high affinity. D609 neither suppressed endogenous K+ currents in HEK293T cells, nor inhibited the sustained and transient K+ currents of mouse neostriatal neurons, but blocked a KCNQ1/KCNE1-like current in neostriatal neurons. D609 potently blocked IKs, the cardiac KCNQ1/KCNE1 channel, in guinea pig cardiac muscle cells. The action of D609 on KCNQ1/KCNE1 depended on the usage of the channel, suggesting that D609 binds to the channel in the open state. We identified D609 as a potent and specific open channel blocker of KCNQ1/KCNE1. Because KCNQ1/KCNE1 is highly expressed in the heart, the inner ear and the pancreas, D609, when used as an antitumor or antiviral drug, may affect the function of a number of organs in vivo even when used at low concentrations.

Lamotrigine Reduces ß-Site AßPP-Cleaving Enzyme 1 Protein Levels Through Induction of Autophagy.

Lamotrigine (LTG), a broad-spectrum anti-epileptic drug widely used in treatment for seizures, shows potential efficacy in Alzheimer's disease (AD) therapy. Chronic LTG treatment rescues the suppressed long-term potentiation, loss of spines and cognitive deficits in AßPP/PS1 mice, known to overexpress a chimeric mouse/human mutant amyloid-ß protein precursor (AßPP) and a mutant human presenilin 1 (PS1). These changes are accompanied by reduction of amyloid-ß (Aß) plaques density and of levels of ß-C-terminal fragment of AßPP (ß-CTF), a fragment of AßPP cleaved by ß-secretase. These results suggest LTG treatment reduces Aß production, possibly through modulation of cleavage of AßPP by ß-secretase. However, the underlying mechanisms still remain unclear. In this study, decreased protein levels, but not mRNA levels of ß-site AßPP-cleaving enzyme 1 (BACE1), were observed in cultured HEK293 cells and the brains of AßPP/PS1 transgenic mice upon LTG treatment. Moreover, LTG treatment suppressed mammalian target of rapamycin (mTOR) signaling, while enhancing activation of cAMP response element binding protein (CREB), two signaling pathways essential for autophagy induction. LTG treatment increased the numbers of LC3-GFP + puncta and LC3-II levels in HEK293 cells, indicating an induction of autophagy. The downregulation of BACE1 by LTG treatment was prevented by the autophagy inhibitor 3-Methyladenine. Therefore, this study shows that LTG treatment reduces the protein levels of BACE1 through activation of autophagy, possibly via inhibition of mTOR signaling and activation of CREB.

Caspr4 interaction with LNX2 modulates the proliferation and neuronal differentiation of mouse neural progenitor cells.

Contactin-associated protein 4 (Caspr4), also known as contactin-associated protein-like protein (CNTNAP4), is expressed in various regions of the brain. Recent reports suggest that CNTNAP4 is a susceptibility gene of autism spectrum disorders (ASDs). However, the molecular function of Caspr4 in the brain has yet to be identified. In this study, we show an essential role of Caspr4 in neural progenitor cells (NPCs). Caspr4 is expressed in NPCs in the subventricular zone (SVZ), a neurogenic region in the developing cortex. Knocking down of Caspr4 enhances the proliferation of NPCs derived from the SVZ of embryonic day 14 mouse. Neuronal differentiation is increased by overexpression of Caspr4, but decreased by knocking down of Caspr4 in cultured mouse NPCs. Transfection of the intracellular domain of Caspr4 (C4ICD) rescues the abnormal decreased neuronal differentiation of Caspr4-knocking down NPCs. Ligand of Numb protein X2 (LNX2), a binding partner of Numb, interacts with Caspr4 in a PDZ domain-dependent manner and plays a similar role to Caspr4 in NPCs. Moreover, transfection of LNX2 rescues the decreased neuronal differentiation in Caspr4-knocking down NPCs. In contrast, transfection of C4ICD fails to do so in LNX2-knocking down NPCs. These results indicate that Caspr4 inhibits neuronal differentiation in a LNX-dependent manner. Therefore, this study reveals a novel role of Caspr4 through LNX2 in NPCs, which may link to the pathogenesis of ASDs.

[Abnormal expression of APRIL in colorectal cancer cells promotes tumor growth and metastasis].

OBJECTIVE: To investigate the effects of a proliferation-inducing ligand (APRlL) on colorectal cancer (CRC) cell growth and migration, and to observe the role of APRIL in CRC biological behavior. METHODS: The siRNA plasmid vector targeting APRIL gene (APRIL-siRNA) was transfected into human colorectal cancer SW480 cells and recombinant human APRIL (rhAPRIL) was used to stimulate human colorectal cancer HCT-116 cells. Cell proliferation activity was analyzed using cell counting kit-8 (CCK-8), cell cycle was detected by flow cytometry, and the protein expression of cyclin D1, p21 and Bcl-2 was detected by Western blot analysis. Tumor cell migration and invasion were measured by Transwell chambers. RT-PCR was applied to examine the mRNA expression level of MMP-2 and MMP-9. APRIL-siRNA was used to transfect directly SW480 cells, which were injected subcutaneously into nude mice, then the tumor growth and metastasis were observed. RESULTS: Cell proliferation ability of APRIL-siRNA-transfected SW480 cells was drastically repressed, and the percentage of G0/G1 phase cells was significantly increased (t = 4.12, P < 0.05), accompanied with depressed cyclin D1, Bcl-2 expression and elevated p21 expression. Cell proliferation ability of rhAPRIL-stimulated HCT-116 cells was promoted with a decreased G0/G1 phase ratio (t = 3.31, P < 0.05). cyclin D1 and Bcl-2 protein expression was up-regulated while p21 was down-regulated by rhAPRIL stimulation. Metastatic and invasive capacities of APRIL-siRNA-transfected SW480 cells were significantly inhibited compared with their respective controls (both P < 0.05), accompanied with the deregulated MMP-2 and MMP-9 mRNA expression. Metastatic and invasive capacities of rhAPRIL-stimulated HCT-116 cells were promoted with up-regulated MMP-2 and MMP-9 mRNA expression(both P < 0.05). Tumor growth in the group transfected with APRIL-siRNA appeared to be slower than that in the control groups and the expression of MMP-2, MMP-9 in tumor tissues was depressed in the APRIL-siRNA group. CONCLUSIONS: APRIL facilitates tumor growth and metastasis, and is associated with carcinogenesis and prognosis. Our findings suggest that APRIL might be used as a novel target for the intervention and therapy of colorectal cancer.

Deficiency of sphingomyelin synthase-1 but not sphingomyelin synthase-2 causes hearing impairments in mice.

Sphingomyelin (SM) is a sphingolipid reported to function as a structural component of plasma membranes and to participate in signal transduction. The role of SM metabolism in the process of hearing remains controversial. Here, we examined the role of SM synthase (SMS), which is subcategorized into the family members SMS1 and SMS2, in auditory function. Measurements of auditory brainstem response (ABR) revealed hearing impairment in SMS1−/− mice in a low frequency range (4­16 kHz). As a possible mechanism of this impairment, we found that the stria vascularis (SV) in these mice exhibited atrophy and disorganized marginal cells. Consequently, SMS1−/− mice exhibited significantly smaller endocochlear potentials (EPs). As a possible mechanism for EP reduction, we found altered expression patterns and a reduced level of KCNQ1 channel protein in the SV of SMS1−/− mice. These mice also exhibited reduced levels of distortion product otoacoustic emissions. Quantitative comparison of the SV atrophy, KCNQ1 expression, and outer hair cell density at the cochlear apical and basal turns revealed no location dependence, but more macrophage invasion into the SV was observed in the apical region than the basal region, suggesting a role of cochlear location-dependent oxidative stress in producing the frequency dependence of hearing loss in SMS1−/− mice. Elevated ABR thresholds, decreased EPs, and abnormal KCNQ1 expression patterns in SMS1−/− mice were all found to be progressive with age. Mice lacking SMS2, however, exhibited neither detectable hearing loss nor changes in their EPs. Taken together, our results suggest that hearing impairments occur in SMS1−/− but not SMS2−/− mice. Defects in the SV with subsequent reductions in EPs together with hair cell dysfunction may account, at least partially, for hearing impairments in SMS1−/− mice.

[Improvement of cervical microenvironment after treatment of chronic cervicitis with focused ultrasound in infertility women].

OBJECTIVE: To investigate the effects of focused ultrasound (FUS) treatment on cervical microenvironment in infertility women with chronic cervicitis. METHODS: A total of 10 women treated in Infertility Clinic of Obstetrics and Gynecology Hospital of College of Medicine of Zhejiang University were assessed. The women aged from 25 to 34 with normal menstrual cycles had moderate or severe cervical erosion. Ultrasound showed they had normal ovulation. The sperms of their husbands had normal motility and number. The FUS they received had a focal depth range of 4 - 6 mm, a resonant frequency of 9 - 11 MHz, and an output power of 3.5 W. The follow-up time was three months. The changes of cervical mucus and the results of postcoital test were evaluated. The clinical effects on cervical erosion and complications were also evaluated. RESULT: In 6 cases of severe cervical erosion, 2 were cured, 2 were improved significantly (more than 50 % reduction of erosion area) and 2 were improved (less than 50 % reduction of erosion area). In 4 cases of moderate cervical erosion, 2 were cured, 2 were improved significantly. After the treatment, the median of cervical mucus score during LH peak were increased from 11 to 13 (Wilcoxon test, P=0.014). Postcoital test showed that the median of highly motile sperm (grade III and grade II) of 5 high-power field were increased from 22 to 52 (Wilcoxon test, P=0.015). Mild side effects without medical intervention included vaginal fluid in all 10 women, vaginal spotting in 2 women. No serious side effects were observed. CONCLUSION: The focused ultrasound therapy can help to improve the cervical microenvironment for infertility women with moderate or severe cervical erosion without serious side effects.