Association of Vitamin D Levels with Risk of Cognitive Impairment and Dementia: A Systematic Review and Meta-Analysis of Prospective Studies.

Background: Emerging evidence suggests the potential relationship between vitamin D deficiency and risk of cognitive impairment or dementia. To what extent the excess risk of dementia conferred by vitamin D deficiency is less clear. Objective: We summarized the current evidence from several aspects and further quantified these associations. Methods: We collected relevant prospective cohort studies by searching PubMed, Embase and Cochrane up to July 2023. The pooled relative risks (RR) were evaluated by random-effects models. Dose-response analyses were conducted by the method of two-stage generalized least squares regression. Results: Of 9,267 identified literatures, 23 were eligible for inclusion in the meta-analyses, among which 9 and 4 literatures were included in the dose-response analyses for the risk of dementia and Alzheimer's disease (AD). Vitamin D deficiency exhibited a 1.42 times risk for dementia (95% confidence interval (CI) = 1.21-1.65) and a 1.57-fold excess risk for AD (95% CI = 1.15-2.14). And vitamin D deficiency was associated with 34% elevated risk with cognitive impairment (95% CI = 1.19-1.52). Additionally, vitamin D was non-linearly related to the risk of dementia (pnonlinearity = 0.0000) and AD (pnonlinearity = 0.0042). The approximate 77.5-100 nmol/L 25-hydroxyvitamin D [25(OH)D] was optimal for reducing dementia risk. And the AD risk seemed to be decreased when the 25(OH)D level >40.1 nmol/L. Conclusions: Vitamin D deficiency was a risk factor for dementia, AD, and cognitive impairment. The nonlinear relationships may further provide the optimum dose of 25(OH)D for dementia prevention.

Senktide blocks aberrant RTN3 interactome to retard memory decline and tau pathology in social isolated Alzheimer's disease mice.

Sporadic or late-onset Alzheimer's disease (LOAD) accounts for more than 95% of Alzheimer's disease (AD) cases without any family history. Although genome-wide association studies have identified associated risk genes and loci for LOAD, numerous studies suggest that many adverse environmental factors, such as social isolation, are associated with an increased risk of dementia. However, the underlying mechanisms of social isolation in AD progression remain elusive. In the current study, we found that 7 days of social isolation could trigger pattern separation impairments and presynaptic abnormalities of the mossy fibre-CA3 circuit in AD mice. We also revealed that social isolation disrupted histone acetylation and resulted in the downregulation of 2 dentate gyrus (DG)-enriched miRNAs, which simultaneously target reticulon 3 (RTN3), an endoplasmic reticulum protein that aggregates in presynaptic regions to disturb the formation of functional mossy fibre boutons (MFBs) by recruiting multiple mitochondrial and vesicle-related proteins. Interestingly, the aggregation of RTN3 also recruits the PP2A B subunits to suppress PP2A activity and induce tau hyperphosphorylation, which, in turn, further elevates RTN3 and forms a vicious cycle. Finally, using an artificial intelligence-assisted molecular docking approach, we determined that senktide, a selective agonist of neurokinin3 receptors (NK3R), could reduce the binding of RTN3 with its partners. Moreover, application of senktide in vivo effectively restored DG circuit disorders in socially isolated AD mice. Taken together, our findings not only demonstrate the epigenetic regulatory mechanism underlying mossy fibre synaptic disorders orchestrated by social isolation and tau pathology but also reveal a novel potential therapeutic strategy for AD.

Tau pathology epigenetically remodels the neuron-glial cross-talk in Alzheimer's disease.

The neuron-glia cross-talk is critical to brain homeostasis and is particularly affected by neurodegenerative diseases. How neurons manipulate the neuron-astrocyte interaction under pathological conditions, such as hyperphosphorylated tau, a pathological hallmark in Alzheimer's disease (AD), remains elusive. In this study, we identified excessively elevated neuronal expression of adenosine receptor 1 (Adora1 or A1R) in 3×Tg mice, MAPT P301L (rTg4510) mice, patients with AD, and patient-derived neurons. The up-regulation of A1R was found to be tau pathology dependent and posttranscriptionally regulated by Mef2c via miR-133a-3p. Rebuilding the miR-133a-3p/A1R signal effectively rescued synaptic and memory impairments in AD mice. Furthermore, neuronal A1R promoted the release of lipocalin 2 (Lcn2) and resulted in astrocyte activation. Last, silencing neuronal Lcn2 in AD mice ameliorated astrocyte activation and restored synaptic plasticity and learning/memory. Our findings reveal that the tau pathology remodels neuron-glial cross-talk and promotes neurodegenerative progression. Approaches targeting A1R and modulating this signaling pathway might be a potential therapeutic strategy for AD.

miR-135a-5p mediates memory and synaptic impairments via the Rock2/Adducin1 signaling pathway in a mouse model of Alzheimer's disease.

Aberrant regulation of microRNAs (miRNAs) has been implicated in the pathogenesis of Alzheimer's disease (AD), but most abnormally expressed miRNAs found in AD are not regulated by synaptic activity. Here we report that dysfunction of miR-135a-5p/Rock2/Add1 results in memory/synaptic disorder in a mouse model of AD. miR-135a-5p levels are significantly reduced in excitatory hippocampal neurons of AD model mice. This decrease is tau dependent and mediated by Foxd3. Inhibition of miR-135a-5p leads to synaptic disorder and memory impairments. Furthermore, excess Rock2 levels caused by loss of miR-135a-5p plays an important role in the synaptic disorder of AD via phosphorylation of Ser726 on adducin 1 (Add1). Blocking the phosphorylation of Ser726 on Add1 with a membrane-permeable peptide effectively rescues the memory impairments in AD mice. Taken together, these findings demonstrate that synaptic-related miR-135a-5p mediates synaptic/memory deficits in AD via the Rock2/Add1 signaling pathway, illuminating a potential therapeutic strategy for AD.

Loss of ferroportin induces memory impairment by promoting ferroptosis in Alzheimer's disease.

Iron homeostasis disturbance has been implicated in Alzheimer's disease (AD), and excess iron exacerbates oxidative damage and cognitive defects. Ferroptosis is a nonapoptotic form of cell death dependent upon intracellular iron. However, the involvement of ferroptosis in the pathogenesis of AD remains elusive. Here, we report that ferroportin1 (Fpn), the only identified mammalian nonheme iron exporter, was downregulated in the brains of APPswe/PS1dE9 mice as an Alzheimer's mouse model and Alzheimer's patients. Genetic deletion of Fpn in principal neurons of the neocortex and hippocampus by breeding Fpnfl/fl mice with NEX-Cre mice led to AD-like hippocampal atrophy and memory deficits. Interestingly, the canonical morphological and molecular characteristics of ferroptosis were observed in both Fpnfl/fl/NEXcre and AD mice. Gene set enrichment analysis (GSEA) of ferroptosis-related RNA-seq data showed that the differentially expressed genes were highly enriched in gene sets associated with AD. Furthermore, administration of specific inhibitors of ferroptosis effectively reduced the neuronal death and memory impairments induced by Aß aggregation in vitro and in vivo. In addition, restoring Fpn ameliorated ferroptosis and memory impairment in APPswe/PS1dE9 mice. Our study demonstrates the critical role of Fpn and ferroptosis in the progression of AD, thus provides promising therapeutic approaches for this disease.

Tau overexpression impairs neuronal endocytosis by decreasing the GTPase dynamin 1 through the miR-132/MeCP2 pathway.

Tauopathies are a class of neurodegenerative diseases that are characterized by pathological aggregation of tau protein, which is accompanied by synaptic disorders. However, the role of tau in endocytosis, a fundamental process in synaptic transmission, remains elusive. Here, we report that forced expression of human tau (hTau) in mouse cortical neurons impairs endocytosis by decreasing the level of the GTPase dynamin 1 via disruption of the miR-132-MeCP2 pathway; this process can also be detected in the brains of Alzheimer's patients and hTau mice. Our results provide evidence for a novel role of tau in the regulation of presynaptic function.

BuPiHeWei Decoction Ameliorates 5-Fu-Induced Intestinal Mucosal Injury in the Rats by Regulating the TLR-4/NF-κB Signaling Pathway.

BuPiHeWei (BPHW) decoction, a classic Traditional Chinese Medicinal (TCM) prescription, has been widely used in clinical practice to relieve digestive symptoms caused by chemotherapy, such as diarrhea and vomiting. The present study aimed to investigate whether BPHW decoction exerted a protective role in the 5-Fu-induced intestinal mucosal injury in the rats by regulating the mechanisms of TLR-4/NF-κB signaling pathway. There were 35 Sprague Dawley rats randomly divided into four groups: normal control group, 5-Fu group, 5-Fu + BPHW decoction group (10.5 g/kg, for five continuous days), and 5-Fu + Bacillus licheniformis capsule group (0.2 g/kg, for five continuous days). Animal models were established by intraperitoneal injection of 5-Fu (30 mg/Kg, for five consecutive days). At the end of the treatment period, body weight, diarrhea score, and histological examination were examined. Furthermore, the expression of TLR-4/NF-κB pathway was detected to reveal its mechanism. The results showed that BPHW decoction effectively reduced diarrhea score and increased body weight and height of villi after 5-Fu chemotherapy. In addition, BPHW decoction could significantly inhibit the expression of TLR-4, NF-κB, and inflammatory factors (including TNF-α, IL-1ß, and IL-6) in the intestine, and the efficacy was significantly higher than that of Bacillus licheniformis capsule. In summary, BPHW decoction might be considered an effective drug to alleviate intestinal mucosal injury in the rats induced by 5-Fu.

Cattle encephalon glycoside and ignotin injection improves cognitive impairment in APPswe/PS1dE9 mice used as multitarget anti-Alzheimer's drug candidates.

BACKGROUND: Cattle encephalon glycoside and ignotin injection (CEGI), a multitargeted neurotrophic drug, has been widely used in the treatment of central and peripheral nerve injuries, such as stroke, hypoxic ischemic encephalopathy, and diabetic neuropathy in the People's Republic of China. However, data regarding the effect of CEGI on Alzheimer's disease (AD) remain scarce. The present study aimed to investigate the effect of CEGI on learning and memory in an APPswe/PS1dE9 double-transgenic mouse model, a suitable animal model of AD, and elucidate its possible mechanisms. MATERIALS AND METHODS: Five-month-old APP/PS1 mice were intraperitoneally administered 6.6 mL/kg or 13.2 mL/kg of CEGI for 1 month. After 1 month of administration, all mice received Morris water maze training and a probe test. Mouse brain sections were detected by standard biochemical and immunohistochemical measures. RESULTS: CEGI treatment significantly improved the spatial learning and memory deficits and decreased cerebral amyloid-ß42 levels in brain homogenates of APP/PS1 mice. CEGI treatment elevated the activities of superoxide dismutase, and reduced the levels of malondialdehyde. CEGI attenuated neuronal damage in the hippocampus of APP/PS1 mice and upregulated protein and gene expression of Bcl-2 and the ratio of Bcl-2/Bax. CEGI treatment decreased the number of Iba1(+) activated microglia in the cortex of the APP/PS1 mice. CONCLUSION: Our results showed that CEGI prevents memory impairment, possibly by decreasing the amyloid-ß42 levels in APP/PS1 mice and inhibiting oxidative stress, apoptosis, and inflammation, making CEGI a promising therapeutic agent for AD.

In vivo transplantation of bone marrow mesenchymal stem cells accelerates repair of injured gastric mucosa in rats.

BACKGROUND: Adult stem cells provide a promising alternative for the treatment of injured tissues. We aimed to investigate the effect of in vivo transplantation of bone marrow mesenchymal stem cells (BMMSCs) on injured gastric mucosa in rats. METHODS: The gastric ulcer in rats was induced by indomethacin. BMMSCs from male rats, labeled with the fluorescent cell linker 5,6-carboxyfluorescein diacetate succinimidyl ester (CFDA SE), were transplanted into the female rats via tail vein injection. The healing process of gastric ulcers was monitored by HE staining. The protein levels of vascular endothelial growth factor (VEGF) and the epidermal growth factor receptor (EGFR) in the injured gastric mucosa were determined by immunohistochemistry. RESULTS: At 48 and 72 hours after BMMSCs transplantation, the CFDA SE labeled cells were found scattered in the injured gastric mucosa, but not in the gastric mucosa of control rats. At 72 hours after BMMSCs transplantation, the mean ulcer index was 12.67 ± 2.16 in the BMMSCs transplanted group and 17.33 ± 1.97 in vehicle-treated controls (P < 0.01). Both VEGF and EGFR protein expression levels were significantly higher in the gastric section from the rats that received BMMSCs transplantation as compared to rats without BMMSCs transplantation. CONCLUSION: Autologous BMMSCs transplantation can accelerate gastric ulcer healing in injured gastric mucosa in a rodent model.

Th17 cells are increased with severity of liver inflammation in patients with chronic hepatitis C.

BACKGROUND AND AIM: As a newly identified subset of T helper cells, T-helper 17 cells (Th17) are major mediators of inflammation-associated disease. Some reports have revealed significantly increased Th17 cells in hepatitis B virus-infected patients, and a recent study has demonstrated that hepatitis C virus (HCV)-specific Th17 cells can be induced in vitro and regulated by transforming growth factor-ß. This study attempted to characterize the role of Th17 cells in the disease progression of chronic hepatitis C (CHC). METHODS: The current study enrolled 53 patients with CHC and 23 healthy controls, in which the circulating and liver-infiltrating Th17 cells were monitored. RESULTS: We found that CHC patients had increased proportions of both circulating and liver-infiltrating Th17 cells compared to healthy individuals, and both measures of Th17 cells were correlated with severity of liver inflammation. We further demonstrated that the HCV-specific Th17 cells were correlated with liver damage but not HCV viral replication. CONCLUSIONS: Such a correlation between the severity of liver damage of CHC and Th17 cells illustrated in this study sheds some light on the understanding of the pathogenesis of CHC.

[Effects of baicalin against oxidative stress injury of SH-SY5Y cells by up-regulating SIRT1].

This study is to investigate the effect of baicalin (BL) against oxidative injury stress of SH-SY5Y cells induced by H2O2 and the possible mechanism. SH-SY5Y cells were pre-incubated with baicalin (25, 50, and 100 micromol x L(-1)) for 12 h prior to exposure to H2O2 (150 micromol x L(-1)) for 24 h. The viability of SH-SY5Y cells was measured by MTT assay. The contents of LDH and NO were determined. The percentage of apoptotic cells was assessed by flow cytometry (FCM). The content of Caspase-3 was tested by immunofluorescence histochemical method. BL at 50 and 100 micromol x L(-1) separately increased the cell viability and up-regulated SIRT1, reduced the contents of LDH, NO, Caspase-3 and the apoptotic percentage of SH-SY5Y cells. This study results suggest that baicalin could inhibit the H2O2-induced neuronal apoptosis. The further mechanism studies show that baicalin inhibit apoptosis via reducing Caspase-3 expression and up-regulating SIRT1.

[Study on pancreas of type 1 diabetic mice induced by MLD-STZ using proteomics].

OBJECTIVE: To get a better understanding of the mechanisms underlying type 1 diabetes mellitus, the differentially expressed pancreatic proteins from multiple low-dose streptozotocin (MLD-SIZ) mouse and normal mouse were analyzed and compared. METHODS: 20 male rats were separated into 2 groups (n=10): model mice treated with MLD-STZ and normal mice,differences of pancreatic proteome among in the two groups of mice, were analyzed by two dimensional polyacryamide gel electrophoresis (2DE). Protein quantification was analyzed and the differentially expressed spots were identified using mass spectrometry and MASCOT database searching. RESULTS: Compared with control group, 23 proteins had changed significantly in the model group, 8 proteins expression were up-regulated, 15 proteins expressions down-regulated significantly. Using MALDI-TOF-MS, 15 proteins with significant change were identified by peptide fingerprinting map and the results were searched in MASCOT database. The function analyzed showed that proteins with change were associated with metabolic, anti-oxidant, structural, catalytic enzymes and chaperone, et al. CONCLUSION: Type 1 diabetes is probably exerted via multi-target and multi-path mechanism. The proteins with significant change are newly target for type 1 diabetes early diagnosis and treatment.

[Expression of tau-related protein in spinal cord of patients with Alzheimer's disease].

OBJECTIVE: To study the expression of tau-related protein in spinal cord of Chinese patients with Alzheimer's disease. METHODS: Gallays-Braak stain and immunohistochemical study for tau protein (AT8) were carried out in the spinal cord tissue (T2, T8, T10, L2 and S2 segments) of 3 Chinese patients with Alzheimer's disease. Seven age-matched cases without evidence of dementia or neurologic disease were used as controls. RESULTS: Neurofibrillary tangles were identified in the neurons of anterior horn in 2 Alzheimer's disease cases but none was observed in the controls. Tau-positive axons and astroglia were detected in all Alzheimer's disease cases. Tau immunoreactivity in spinal cord of the patients correlated with that in brain tissue. CONCLUSION: The expression of tau-related protein is demonstrated in the spinal cord of Alzheimer's disease patients suggesting that axonal transport defect may play a role in the pathogenesis of Alzheimer's disease.

[Effect of Shuyusan on neuropeptide Y and serotonin expression in the hippocampal neurons of rats with chronic mild unpredictable stress-induced depression].

OBJECTIVE: To investigate the effect of Shuyusan decoction on neuropeptide Y (NPY) and serotonin (5-HT) expression in the hippocampus and plasma of rats with chronic mild unpredictable stressors depression. METHODS: Fifty Wistar rats were randomly divided into 5 groups, namely the normal control group, model group, fluoxetine group, and high- and low-dose Shuyusan groups. Except for those in the normal control group, all the rats were subjected to chronic mild unpredicted stress for 21 consecutive days with corresponding treatments. Open-field test was used to assess the behavioral changes of the rats. The content of NPY in the hippocampus and plasma was detected by competitive enzyme-linked immunosorbent assay, and immunocytochemistry was used to determine the expression of 5-HT in the hippocampus. RESULTS: NPY levels in the hippocampus and plasma was significantly decreased in the model group as compared with that in the normal control group (P<0.05). Treatments with fluoxetine and high-dose Shuyusan both significantly increased NPY levels in the hippocampus and plasma in the depressive rats (P<0.05), resulting also in significantly increased 5-HT-immunoreactive neurons in the cerebral cortex and hippocampus and the average optical density (P<0.05). CONCLUSION: Shuyusan decoction can effectively increase plasma and hippocampus NPY levels and the number of 5-HT-positive neurons in the cerebral cortex and happocampus of rats with chronic mild unpredictable stress-induced depression.

[An experimental research of neuroglobin expression changes and neural apoptosis after traumatic brain injury].

OBJECTIVE: To study the expression changes of neuroglobin in rats with the model of diffuse traumatic brain injury and explore the relationship between the neuroglobin and neuron apoptosis in traumatic brain injury. METHODS: The diffuse traumatic brain injury of rats was induced by the Marmarou's 'weight-drop' device. And the immunohistochemical technique was used to detect the expression changes of neuroglobin and neuron apoptosis in rat brain at different time points post-injury. RESULTS: The expression of neuroglobin increased twice and reached peaks at 2 hours and 72 hours post-injury respectively. And the increased expression of neuroglobin from 30 minutes to 1 hour post-injury and from 48 hours to 72 hours post-injury accompanied with the decreased expression ratio of Bax to Bcl-2. CONCLUSION: The increased expression of neuroglobin in traumatic brain injury informed us that neuroglobin had anti-apoptosis action in post-injury neuron. It could protect the neuron from traumatic stress and secondary ischemia and hypoxia insults during ultra-early and acute stages.

[Pathologic diagnosis of non-Alzheimer type dementia].

OBJECTIVE: To characterize histopathologic features of non-Alzheimer type dementia. METHODS: Bodian, Gallyas-Braak silver staining, tau and ubiquitin immunohistochemistry were applied in an analysis of 22 cases of autopsy-proven neurodegenerative dementia. Appearance, distribution and immunoreactivity of neuronal and glial inclusions in the brain were observed. The final histological diagnoses were made according to the pathological criteria for several types of common non-Alzheimer type dementia. RESULTS: Among the 22 cases of neurodegenerative dementia, 12 cases were identified as non-Alzheimer type dementia, including Pick's disease (2 cases), progressive supranuclear palsy (3 cases) and corticobasal degeneration (3 cases), dementia with Lewy bodies (1 case), and Parkinson's disease (3 cases). Another 10 cases consisted of pure Alzheimer's disease (AD, 9 cases) and AD combined with argyrophilic grain disease (1 case). Characteristic neuronal and glial inclusions, such as classical and cortical Lewy body, Pick body, Globous NFTs, astrocytic plaque and tufted astrocyte, argyrophilic grain were found in the brains of non-Alzheimer type dementia. Classical and cortical Lewy bodies were not argyrophilic but were immunoreactive to ubiquitin. Pick bodies, Globous NFTs, astrocytic plaques, tufted astrocytes and argyrophilic grains were all argyrophilic. Pick bodies showed tau and ubiquitin immunoreactivity. However, Globous NFTs, astrocytic plaques, tufted astrocytes, and argyrophilic grains were reactive only to tau immunohistochemistry. CONCLUSIONS: Findings of characteristic neuronal and glial inclusions may help to differentiate non-Alzheimer type dementia from AD, and in conjunction with Gallyas-Braak staining and immunohistochemistry for tau and ubiquitin, to further define histopathologic subcategories of non-Alzheimer type dementia.

[Morphological and quantatitive capillary changes in aging human brain].

OBJECTIVE: To investigate morphological changes of capillary in aging brain and explore the role of vascular factor in brain aging. METHODS: Twenty-eight brains of individuals (mean age 65 years) who died without clinical or pathological involvement of nervous system and 6 brains of Alzheimer's disease (AD) patients (mean age 83 years) were obtained at autopsy. Sections from frontal lobe, occipital lobe, striatum and hippocampus of normal subjects and sections from hippocampus of AD patients were used for hematoxylin eosin (HE), lox fast blue (LFB), toluidine blue stains and ulex europaeus agglutinin (UEA) immunostaining. After observations of morphological changes of neuron and capillary, computer-aid image analysis was performed to quantify numerical density and area density of neuron and capillary in frontal lobe, occipital lobe, putamen, CA3 sector of normal subjects and CA3 sector of AD patients. Numerical ratio and area ratio of neuron and capillary were then calculated. Correlations between neuron/capillary ratio and age were estimated using Pearson's correlation test. Difference of neuron/capillary ratio in CA3 sectors between AD patients and advanced aged normal subjects (> 75 years) was analyzed with Student's t-test. RESULTS: Several pathological microvascular changes, including increased tortuosity, looping, bundling, stringing, and effacement of endothelia were seen in aged subjects and more prevalent in AD patients. Numerical ratio and area ratio of neuron and capillary of frontal lobe, occipital lobe and putamen significantly increased with age in normal aging subjects. CONCLUSIONS: Morphological changes and relative decrease in number and capacity of capillary in aging brain may reduce cerebral blood flow and metabolism, and consequently result in functional impairment of aging brain. Vascular factors may play an important role in the development of brain aging.