Endothelial BACE1 Impairs Cerebral Small Vessels via Tight Junctions and eNOS.

BACKGROUND: Cerebral small vessel injury, including loss of endothelial tight junctions, endothelial dysfunction, and blood-brain barrier breakdown, is an early and typical pathology for Alzheimer's disease, cerebral amyloid angiopathy, and hypertension-related cerebral small vessel disease. Whether there is a common mechanism contributing to these cerebrovascular alterations remains unclear. Studies have shown an elevation of BACE1 (ß-site amyloid precursor protein cleaving enzyme 1) in cerebral vessels from cerebral amyloid angiopathy or Alzheimer's disease patients, suggesting that vascular BACE1 may involve in cerebral small vessel injury. METHODS: To understand the contribution of vascular BACE1 to cerebrovascular impairments, we combined cellular and molecular techniques, mass spectrometry, immunostaining approaches, and functional testing to elucidate the potential pathological mechanisms. RESULTS: We observe a 3.71-fold increase in BACE1 expression in the cerebral microvessels from patients with hypertension. Importantly, we discover that an endothelial tight junction protein, occludin, is a completely new substrate for endothelial BACE1. BACE1 cleaves occludin with full-length occludin reductions and occludin fragment productions. An excessive cleavage by elevated BACE1 induces membranal accumulation of caveolin-1 and subsequent caveolin-1-mediated endocytosis, resulting in lysosomal degradation of other tight junction proteins. Meanwhile, membranal caveolin-1 increases the binding to eNOS (endothelial nitric oxide synthase), together with raised circulating Aß (ß-amyloid peptides) produced by elevated BACE1, leading to an attenuation of eNOS activity and resultant endothelial dysfunction. Furthermore, the initial endothelial damage provokes chronic reduction of cerebral blood flow, blood-brain barrier leakage, microbleeds, tau hyperphosphorylation, synaptic loss, and cognitive impairment in endothelial-specific BACE1 transgenic mice. Conversely, inhibition of aberrant BACE1 activity ameliorates tight junction loss, endothelial dysfunction, and memory deficits. CONCLUSIONS: Our findings establish a novel and direct relationship between endothelial BACE1 and cerebral small vessel damage, indicating that abnormal elevation of endothelial BACE1 is a new mechanism for cerebral small vessel disease pathogenesis.

Peripheral biomarkers to differentiate bipolar depression from major depressive disorder: a real-world retrospective study.

BACKGROUND: Bipolar depression (BPD) is often misdiagnosed as a major depressive disorder (MDD) in clinical practice, which may be attributed to a lack of robust biomarkers indicative of differentiated diagnosis. This study analysed the differences in various hormones and inflammatory markers to explore peripheral biomarkers that differentiate BPD from MDD patients. METHODS: A total of 2,048 BPD and MDD patients were included. A panel of blood tests was performed to determine the levels of sex hormones, stress hormones, and immune-related indicators. Propensity score matching (PSM) was used to control for the effect of potential confounders between two groups and further a receiver operating characteristic (ROC) curve was used to analyse the potential biomarkers for differentiating BPD from MDD. RESULTS: Compared to patients with MDD, patients with BPD expressed a longer duration of illness, more hospitalisations within five years, and an earlier age of onset, along with fewer comorbid psychotic symptoms. In terms of biochemical parameters, MDD patients presented higher IgA and IgM levels, while BPD patients featured more elevated neutrophil and monocyte counts. ROC analysis suggested that combined biological indicators and clinical features could moderately distinguish between BPD and MDD. In addition, different biological features exist in BPD and MDD patients of different ages and sexes. CONCLUSIONS: Differential peripheral biological parameters were observed between BPD and MDD, which may be age-sex specific, and a combined diagnostic model that integrates clinical characteristics and biochemical indicators has a moderate accuracy in distinguishing BPD from MDD.

Clinicopathologic features and diagnostic challenges of small cluster pattern appendiceal neuroendocrine tumors.

Appendiceal neuroendocrine neoplasms (NENs) can present with various growth patterns including the traditional triad of histologic patterns-insular, trabecular and tubular. A small cluster pattern was also found in this study and the literature on this specific morphology is limited. In this study, we conducted a comprehensive review of appendiceal NENs from our institution over a ten-year period. Clinical and demographic data were obtained from medical records. Immunohistochemical stains were performed with antibodies specific for synaptophysin, chromogranin, INSM1, CD56, serotonin and peptide YY. The small cluster pattern was found in 29.4 % of all cases evaluated. The tumor cells in these cases were predominantly located at the distal tip of the appendix, associated with fibrous obliteration. These tumors were smaller in size and tended towards less advanced tumor stage, with reduced incidence of lymphovascular and/or perineural invasion. Chromogranin expression was identified in 76 % of these cases. There is a heterogeneous hormone profile with 46.7 % serotonin and 33.3 % peptide YY. In conclusion, the small cluster pattern NENs present with unique histological features and hormone expression profile. Among the various neuroendocrine markers, INSM1 showed superior diagnostic performance, with high sensitivity and minimal non-specific staining.

Sex-Specific Regulation of ß-Secretase: A Novel Estrogen Response Element (ERE)-Dependent Mechanism in Alzheimer's Disease.

Women have a higher prevalence and incidence of Alzheimer's disease (AD) than age-matched men, and loss of estrogen might be partially responsible for the higher risk of AD in aged women. While ß-secretase (BACE1) plays an important role in AD pathogenesis, whether BACE1 involved the sex difference in AD pathology remains unclear. This study investigated the hypothesis that estrogen regulates BACE1 transcription via the estrogen response element (ERE) and designated pathways. Using estrogen receptor (ER) knock-out mice and mutagenesis of EREs in HEK293 cells, we demonstrated sex-specific inhibition of BACE1 transcription by estrogen via direct binding to ERE sites and ERα. We also used a repressor of estrogen receptor activity (REA) and showed that an REA-ERE complex downregulated BACE1. A chromatin immunoprecipitation assay analysis determined that all three EREs at the BACE1 promoter were required for estradiol-mediated downregulation of BACE1 transcription in mice. Last, we confirmed the impairment of the REA pathway in the cortex of female AD patients. Our study identified an estrogen-specific BACE1 transcriptional regulation pathway from cell and animal models to AD patients.SIGNIFICANCE STATEMENT With the increase in the aging population and Alzheimer's disease worldwide, an urgent need to find effective approaches to treat or prevent AD. Women have a higher prevalence and incidence of AD than men. Identification of the sex-specific risk for AD may be valuable for disease prevention. This study evaluated several estrogen response element (ERE) sites on the promoter of ß-secretase (BACE1), a key enzyme for AD pathology. We demonstrated that estrogen downregulated BACE1 transcription through direct binding and complex formation with ERE and cofactors. Our novel findings provide evidence that an estrogen supplement may decrease the risk of AD in menopausal and postmenopausal women. Furthermore, this study demonstrates the "sex-specific" mechanisms of BACE1 as a role in AD pathogenesis.

Synaptotagmin-11 regulates immune functions of microglia in vivo.

Membrane trafficking pathways mediate key microglial activities such as cell migration, cytokine secretion, and phagocytosis. However, the underlying molecular mechanism remains poorly understood. Previously, we found that synaptotagmin-11 (Syt11), a non-Ca2+ -binding Syt associated with Parkinson's disease (PD) and schizophrenia, inhibits cytokine release and phagocytosis in primary microglia. Here we reported the in vivo function of Syt11 in microglial immune responses using an inducible microglia-specific Syt11-conditional-knockout (cKO) mouse strain. Syt11-cKO resulted in activation of microglia and elevated mRNA levels of IL-6, TNF-α, IL-1ß, and iNOS in various brain regions under both resting state and LPS-induced acute inflammation state in adult mice. In a PD mouse model generated by microinjection of preformed α-synuclein fibrils into the striatum, a reduced number of microglia migrated toward the injection sites and an enhanced phagocytosis of α-synuclein fibrils by microglia were found in Syt11-cKO mice. To understand the molecular mechanism of Syt11 function, we identified its direct binding proteins vps10p-tail-interactor-1a (vti1a) and vti1b. The linker domain of Syt11 interacted with both proteins and a peptide derived from it competitively inhibited the interaction of Syt11 with vti1a/vti1b in vitro and in cells. Importantly, application of this peptide induced more cytokine secretion in wild-type microglia upon LPS treatment, phenocopying defects in Syt11 knockdown cells. Altogether, we propose that Syt11 inhibits microglial activation in vivo and regulates cytokine secretion through interactions with vti1a and vti1b.

Hormonal and inflammatory signatures of different mood episodes in bipolar disorder: a large-scale clinical study.

BACKGROUND: Bipolar disorder (BD) is characterized by intensive mood fluctuations. While hormones imbalance plays important role in the mood swings, it is unknown whether peripheral hormones profiles could differentiate the manic and depressive mood episodes in BD. In this study, we investigated the changes of various hormones and inflammatory markers across distinct mood episodes of BD in a large clinical study to provide mood episode-specific peripheral biomarkers for BD. METHODS: A total of 8332 BD patients (n = 2679 depressive episode; n = 5653 manic episode) were included. All patients were in acute state of mood episodes and need hospitalization. A panel of blood tests were performed for levels of sex hormones (serum levels of testosterone, estradiol, and progesterone), stress hormones (adrenocorticotropic hormone and cortisol), and an inflammation marker (C-reactive protein, CRP). A receiver operating characteristic (ROC) curve was used to analyze the discriminatory potential of the biomarkers for mood episodes. RESULTS: In overall comparison between mood episodes, the BD patients expressed higher levels of testosterone, estradiol, progesterone, and CRP (P < 0.001) and lower adrenocorticotropic hormone (ACTH) level (P < 0.001) during manic episode. The episode-specific changes of testosterone, ACTH, and CRP levels remained between the two groups (P < 0.001) after correction for the confounding factors including age, sex, BMI, occupation, marital status, tobacco use, alcohol consumption, psychotic symptoms, and age at onset. Furthermore, we found a sex- and age-specific impact of combined biomarkers in mood episodes in male BD patients aged ≥ 45 years (AUC = 0.70, 95% CI, 0.634-0.747), not in females. CONCLUSIONS: While both hormone and inflammatory change is independently associated with mood episodes, we found that the combination of sex hormones, stress hormones and CRP could be more effective to differentiate the manic and depressive episode. The biological signatures of mood episodes in BD patients may be sex- and age-specific. Our findings not only provide mood episode-related biological markers, but also better support for targeted intervention in BD treatments.

Oral alloantigen exposure promotes donor-specific tolerance in a mouse model of minor-mismatched skin transplantation.

Oral antigen exposure is a powerful, non-invasive route to induce immune tolerance to dietary antigens, and has been modestly successful at prolonging graft survival in rodent models of transplantation. To harness the mechanisms of oral tolerance for promoting long-term graft acceptance, we developed a mouse model where the antigen ovalbumin (OVA) was introduced orally prior to transplantation with skin grafts expressing OVA. Oral OVA treatment pre-transplantation promoted permanent graft acceptance and linked tolerance to skin grafts expressing OVA fused to the additional antigen 2W. Tolerance was donor-specific, as secondary donor-matched, but not third-party allografts were spontaneously accepted. Oral OVA treatment promoted an anergic phenotype in OVA-reactive CD4+ and CD8+ conventional T cells (Tconvs) and expanded OVA-reactive Tregs pre-transplantation. However, skin graft acceptance following oral OVA resisted partial depletion of Tregs and blockade of PD-L1. Mechanistically, we revealed a role for the proximal gut draining lymph nodes (gdLNs) in mediating this effect, as an intestinal infection that drains to the proximal gdLNs prevented tolerance induction. Our study extends previous work applying oral antigen exposure to transplantation and serves as proof of concept that the systemic immune mechanisms supporting oral tolerance are sufficient to promote long-term graft acceptance.

Synaptotagmin-11 inhibits spontaneous neurotransmission through vti1a.

Recent work has revealed that spontaneous release plays critical roles in the central nervous system, but how it is regulated remains elusive. Here, we report that synaptotagmin-11 (Syt11), a Ca2+ -independent Syt isoform associated with schizophrenia and Parkinson's disease, suppressed spontaneous release. Syt11-knockout hippocampal neurons showed an increased frequency of miniature excitatory post-synaptic currents while over-expression of Syt11 inversely decreased the frequency. Neither knockout nor over-expression of Syt11 affected the average amplitude, suggesting the pre-synaptic regulation of spontaneous neurotransmission by Syt11. Glutathione S-transferase pull-down, co-immunoprecipitation, and affinity-purification experiments demonstrated a direct interaction of Syt11 with vps10p-tail-interactor-1a (vti1a), a non-canonical SNARE protein that maintains spontaneous release. Importantly, knockdown of vti1a reversed the phenotype of Syt11 knockout, identifying vti1a as the main target of Syt11 inhibition. Domain analysis revealed that the C2A domain of Syt11 bound vti1a with high affinity. Consistently, expression of the C2A domain alone rescued the phenotype of elevated spontaneous release in Syt11-knockout neurons similar to the full-length protein. Altogether, our results suggest that Syt11 inhibits vti1a-containing vesicles during spontaneous release.

Efficacy of Group Reminiscence Therapy on Cognition, Depression, Neuropsychiatric Symptoms, and Activities of Daily Living for Patients With Alzheimer Disease.

The current study aimed to investigate the effects of group reminiscence therapy on cognitive function, depression, neuropsychiatric symptoms, and activities of daily living in patients with mild-to-moderate Alzheimer disease (AD). A single-blind randomized parallel-design controlled trial was conducted between May 1, 2017, and April 30, 2018. Ninety patients with mild-to-moderate AD recruited from Beijing Geriatric Hospital were randomly allocated into intervention (n = 45) and control groups (n = 45). In the intervention group, group-based reminiscence therapy was performed in two 30- to 45-minute sessions weekly for 12 weeks. Control participants received only conventional drug treatments and routine daily care. Alzheimer disease-related symptoms were evaluated using the Alzheimer's Disease Assessment Scale-Cognitive section, the Cornell Scale for Depression in Dementia (CSDD), the Neuropsychiatric Inventory, and the Barthel Index. Four time points were set for data collection: baseline (before treatment), 4 weeks (during treatment), 12 weeks (end of treatment), and 24 weeks (12 weeks posttreatment). χ2 Tests, independent t tests, repeated-measures analysis of variance, and Bonferroni tests were used for data analysis. Significant improvements in depressive and neuropsychiatric symptoms were found in the intervention group compared to the control group (P < .05). Mean CSDD scores in the intervention group were improved at all 3 time points compared to baseline and showed the greatest effect at 12 weeks (t = 2.076, P = .041) and 24 weeks follow-up (t = 3.834, P = .000) compared to controls. Group reminiscence therapy was effective for improving depressive symptoms and was beneficial for treating neuropsychiatric symptoms in patients with AD.

Sex differences in circulating neuregulin1-ß1 and ß-secretase 1 expression in childhood-onset schizophrenia.

OBJECTIVE: Early-onset schizophrenia is a severe and rare form of schizophrenia that is clinically and neurobiologically continuous with the adult form of schizophrenia. Neuregulin1 (NRG1)-mediated signaling is crucial for early neurodevelopment, which exerts its function by limited ß-secretase 1 (BACE1) proteolysis processing. However, circulating neuregulin1-ß1 (NRG1-ß1), an isoform of NRG1, and its cleavage enzyme BACE1 have not been studied in early-onset patients with schizophrenia. METHODS: In this study, we collected plasma and clinical information from 71 young patients (7 ≤ age years ≤20) with schizophrenia and 53 age- and sex-matched healthy controls. Immunoassay was used to test levels of circulating NRG1-ß1 and BACE1 expression. We further analyzed the relationship of disease-onset age and gender with NRG1-ß1 and BACE1 levels. RESULTS: We found that circulating plasma levels of NRG1-ß1 were significantly decreased in young patients with early-onset schizophrenia. In males with childhood onset schizophrenia (COS), NRG1-ß1 was reduced and was inversely correlated with positive symptom of PANSS; moreover, these male patients with higher plasma BACE1 levels showed more severe general symptoms of PANSS and defective social functioning; whereas, no aforementioned results were found in adolescent-onset schizophrenia (AOS). Notably, young female patients with COS and AOS had no significant change in NRG1-ß1 and BACE1, which demonstrated a sex-dependent effect in early-onset schizophrenia. CONCLUSION: Our results suggest that decreased levels of NRG1-ß1 and its cleavage enzyme BACE1 contribute to increased risk of etiology of schizophrenia. Synthetic biomarkers may have clinical applications for the early diagnosis of male COS.

Rhythmic low-field magnetic stimulation may improve depression by increasing brain-derived neurotrophic factor.

BACKGROUND: Low-field magnetic stimulation (LFMS) has mood-elevating effect, and the increase of brain-derived neurotrophic factor (BDNF) is associated with antidepressant treatment. We evaluated the effects and association with BDNF of rhythmic LFMS in the treatment of major depressive disorder (MDD). METHODS: A total of 22 MDD patients were randomized to rhythmic alpha stimulation (RAS) or rhythmic delta stimulation (RDS), with 5 sessions per week, lasting for 6 weeks. Outcomes assessments included the 17-item Hamilton Depression Rating Scale (HAMD-17), the Hamilton Anxiety Rating Scale (HAMA), and the Clinical Global Impressions-Severity scale (CGI-S) at baseline and at weeks 1, 2, 3, 4, and 6. Serum BDNF level was measured at baseline and at weeks 2, 4, and 6. RESULTS: HAMD-17, HAMA, and CGI-S scores were significantly reduced with both RAS and RDS. RAS patients had numerically greater reductions in HAMD-17 scores than RDS patients (8.9 ± 7.4 vs. 6.2 ± 6.2, effect size [ES]=0.40), while RDS patients had greater improvement in HAMA scores (8.2 ± 8.0 vs. 5.3 ± 5.8, ES=0.42). RAS was associated with clinically relevant advantages in response (54.5% vs. 18.2%, number-needed-to-treat [NNT]=3) and remission (36.4% vs. 9.1%, NNT=4). BDNF increased significantly during the 6-week study period (p<0.05), with greater increases in RAS at weeks 4 and 6 (ES=0.66-0.76) and statistical superiority at week 2 (p=0.034, ES=1.23). Baseline BDNF in the 8 responders (24.8±9.0 ng/ml) was lower than in the 14 nonresponders (31.1±7.3 ng/ml, p=0.083, ES=-0.79), and BDNF increased more in responders (8.9±7.8 ng/ml) than in nonresponders (1.8±3.5 ng/ml, p=0.044). The change in BDNF at week 2 was the most strongly predicted response (p=0.016). CONCLUSIONS: Rhythmic LFMS was effective for MDD. BDNF may moderate/mediate the efficacy of LFMS.

Sex-specific effects of methylenetetrahydrofolate reductase polymorphisms on schizophrenia with methylation changes.

BACKGROUND: Methylenetetrahydrofolate reductase (MTHFR) is the critical enzyme in biotransformation. The polymorphism of MTHFR is a risk factor for schizophrenia. However, whether the MTHFR polymorphism is associated with schizophrenia disease phenotypes and what is the underlying mechanism of MTHFR polymorphism in schizophrenia is under-investigated. In this study, we aim to verify the correlation between MTHFR polymorphisms and clinical features of schizophrenia, while exploring the differential genomic methylation and disease related genes as the potential targets for schizophrenia. METHOD: 242 patients of schizophrenia and 234 matched healthy controls were enrolled in this study. Polymorphisms of MTHFR from three sites (C677T, A1298C, G1793A) were examined by Taqman fluorescence probe method in leukocytes from all subjects. The positive and negative syndrome scale (PANSS), trail making test (TMT) and Clinical Global Impression (CGI) were checked on patients. Genomic methylation was tested and analyzed in fields of differential methylation positions (DMPs) and enrichment of genes that are potentially related to schizophrenia. RESULTS: Schizophrenic patients showed higher frequency of MTHFR polymorphisms at both single and multiple sites than healthy controls. Our data also showed that MTHFR C677T and multiple-site polymorphisms were positively correlated with PANSS positive rating, not negative score in male schizophrenia patients. Furthermore, while a significant reduction of global DNA methylation level was observed in schizophrenic patients, we also identified several genes which differentiated between schizophrenia and healthy controls at methylation levels. CONCLUSIONS: This is a pilot study revealing that MTHFR polymorphisms at both single and multiple sites are related to the risk of schizophrenia and positive symptom of the disease. The risk of MTHFR polymorphism in schizophrenia and the clinical symptoms was only significant in male patients. While the sex-specific risk of MTHFR in schizophrenia is new and the reasons remain unanswered. Our methylation analysis suggested that there was significant hypomethylation of genomic DNA in schizophrenia patients with no sex difference. The correlation between MTHFR polymorphism and schizophrenia may attribute to the change of DNA methylation level, and some certain genes could be potential research objects for MTHFR effects on schizophrenia.

Exercise improves nicotine reward-associated cognitive behaviors and related α7 nAChR-mediated signal transduction in adolescent rats.

The adolescent brain is vulnerable to long-lasting cognitive disturbances resulting from nicotine exposure. Although exercise has been used as an intervention for ameliorating cognitive deficits in various disorders, the effect on cognitive changes induced by nicotine exposure and its underlying mechanisms remain unclear. The purpose of this study was to investigate the effects of exercise on nicotine reward-associated cognitive behaviors in adolescent rats subjected to nicotine conditioned place preference paradigm (CPP). Male adolescent rats were trained on the Go/NoGo task, then subjected to nicotine CPP, and then randomly separated into four groups: sedentary (SED), high- (HE), moderate- (ME), and low-intensity (LE) exercise. Rats in exercise groups performed treadmill running 30 min daily for 10 days. Results showed that MEs had shorter escape latencies in the Morris water maze (MWM) test compared to SEDs. Although time spent and distance swam in the target quadrant significantly increased in both the MEs and HEs, the number of target quadrant crosses increased significantly only in MEs. MEs and HEs showed higher performance accuracy on NoGo and lower scores on CPP tasks. Expression of α7 nicotinic acetylcholine receptors (nAChRs) and downstream signaling molecules increased in MEs in prefrontal cortex but not hippocampus, with α7 nAChRs expression positively associated with NoGo accuracy and MWM probe test performance, but negatively correlated with CPP scores. The findings of this study suggest that moderate-intensity exercise can improve nicotine induced cognitive behaviors, and implicates prefrontal cortical α7 nAChR-mediated signal transduction as a possible mechanism.

Sex differences in drug addiction and response to exercise intervention: From human to animal studies.

Accumulated research supports the idea that exercise could be an option of potential prevention and treatment for drug addiction. During the past few years, there has been increased interest in investigating of sex differences in exercise and drug addiction. This demonstrates that sex-specific exercise intervention strategies may be important for preventing and treating drug addiction in men and women. However, little is known about how and why sex differences are found when doing exercise-induced interventions for drug addiction. In this review, we included both animal and human that pulled subjects from a varied age demographic, as well as neurobiological mechanisms that may highlight the sex-related differences in these potential to assess the impact of sex-specific roles in drug addiction and exercise therapies.

Deficiency of patched 1-induced Gli1 signal transduction results in astrogenesis in Swedish mutated APP transgenic mice.

Normally, sonic hedgehog (Shh) signaling induces high levels of Patched 1 (Ptc1) and its associated transcription factor Gli1 with genesis of specific neuronal progeny. But their roles in the neural stem cells (NSCs), including glial precursor cells (GPCs), of Alzheimer's disease (AD) are unclear. Here, we show that Ptc1 and Gli1 are significantly deficits in the hippocampus of an aged AD transgenic mouse mode, whereas these two molecules are highly elevated at young ages. Our similar findings in autopsied AD brains validate the discovery in AD mouse models. To examine whether Aß peptides, which are a main component of the amyloid plaques in AD brains, affected Ptc1-Gli1 signaling, we treated GPCs with Aß peptides, we found that high dose of Aß1-42 but not Aß1-40 significantly decreased Ptc1-Gli1, while Shh itself was elevated in hippocampal NSCs/GPCs. Furthermore, we found that deficits of Ptc1-Gli1 signaling induced NSCs/GPCs into asymmetric division, which results in an increase in the number of dividing cells including transit-amplifying cells and neuroblasts. These precursor cells commit to apoptosis-like death under the toxic conditions. By this way, adult neural precursor cell pool is exhausted and defective neurogenesis happens in AD brains. Our findings suggest that Ptc1-Gli1 signaling deregulation resulting abnormal loss of GPCs may contribute to a cognition decline in AD brains. The novel findings elucidate a new molecular mechanism of adult NSCs/GPCs on neurogenesis and demonstrate a regulatory role for Ptc1-Gli1 in adult neural circuit integrity of the brain.

Genetic deletion of TNFRII gene enhances the Alzheimer-like pathology in an APP transgenic mouse model via reduction of phosphorylated IκBα.

Tumor necrosis factor receptor II (TNFRII) is one of the TNF receptor superfamily members and our recent pathological studies show that TNFRII is deficient in the brains of Alzheimer's disease (AD). However, the mechanisms of TNFRII in AD pathogenesis remain unclear. In the present study, by using the gene-targeting approach to delete TNFRII in AD transgenic mouse model, we found that, in the brain of APP23 mice with TNFRII deletion (APP23/TNFRII(-/-)), AD-like pathology, i.e. plaque formation and microglial activation, occurs as early as 6 months of age. To test whether the increased levels of Aß plaques was due to elevated Aß, we measured Aß and found that Aß levels indeed were significantly increased at this age. Because ß-secretase, BACE1, is critical enzyme for Aß production, we have examined BACE1 and found that BACE1 is increased in both protein levels and enzymatic activity as early as 6 months of age; Having shown that BACE1 promoter region contains NF-κB binding sites, we found that cytoplasmic NF-κB was elevated and SUMO1 binding to IκBα was decreased. To further verify these findings, we have overexpressed TNFRII and identified that overexpressing TNFRII can reverse the findings from APP23/TNFRII(-/-) mice. Altogether, our results demonstrate novel roles of TNFRII in the regulation of Aß production, suggesting a potential therapeutic strategy for AD by up-regulating TNFRII levels and elevating phosphorylated IκBα by SUMOylation.

Deficiency of GDNF Receptor GFRα1 in Alzheimer's Neurons Results in Neuronal Death.

We have recently developed aged cortical neuron cultures from autopsied human brains with Alzheimer's disease (AD). During the culturing process, we found that glutamatergic cortical neurons from the AD brain lacked a response to glial cell line-derived neurotrophic factor (GDNF), including no axonal regrowth, and were starting to undergo apoptosis. Here we showed that, in cortical neurons from age- and gender-matched cognitively normal control (NC) subjects (NC neurons), GDNF enhanced the expression of GDNF family receptor subtype α1 (GFRα1), but not the other three subtypes (GFRα2, GFRα3, and GFRα4), whereas GDNF failed to induce GFRα1 expression in cortical neurons from the AD brain (AD neurons). The exogenous introduction of GFRα1, but not of its binding partner α1-neural cell adhesion molecule, or RET into AD neurons restored the effect of GDNF on neuronal survival. Moreover, between NC and AD neurons, the AMPA receptor blocker CNQX and the NMDA receptor blocker AP-5 had opposite effects on the GFRα1 expression induced by GDNF. In NC neurons, the presence of glutamate receptors was necessary for GDNF-linked GFRα1 expression, while in AD neurons the absence of glutamate receptors was required for GFRα1 expression by GDNF stimulation. These results suggest that, in AD neurons, specific impairments of GFRα1, which may be linked to glutamatergic neurotransmission, shed light on developing potential therapeutic strategies for AD by upregulation of GFRα1 expression.

Sex differences in cognitive impairment and Alzheimer's disease.

Studies have shown differences in specific cognitive ability domains and risk of Alzheimer's disease between the men and women at later age. However it is important to know that sex differences in cognitive function during adulthood may have their basis in both organizational effects, i.e., occurring as early as during the neuronal development period, as well as in activational effects, where the influence of the sex steroids influence brain function in adulthood. Further, the rate of cognitive decline with aging is also different between the sexes. Understanding the biology of sex differences in cognitive function will not only provide insight into Alzheimer's disease prevention, but also is integral to the development of personalized, gender-specific medicine. This review draws on epidemiological, translational, clinical, and basic science studies to assess the impact of sex differences in cognitive function from young to old, and examines the effects of sex hormone treatments on Alzheimer's disease in men and women.

High activities of BACE1 in brains with mild cognitive impairment.

We recently discovered elevated ß-secretase 1 (BACE1) activity in brains with sporadic Alzheimer disease (AD). Moreover, we also found high levels of BACE1 enzymatic activity in the cerebrospinal fluid from patients with both mild cognitive impairment (MCI) and AD. These results suggest that elevation of BACE1 enzymatic activity may occur early or may contribute to AD. We therefore examined whether BACE1 enzymatic activity was changed in MCI brains. BACE1 activity and tumor necrosis factor (TNF)-α levels were measured by enzymatic assay and ELISA in the temporal cortex from 18 patients with clinically well-characterized AD, 18 patients with MCI, and 18 healthy controls. We found a significant increase in BACE1 activity and protein level in brains of MCI and AD patients. Moreover, increased BACE1 activity correlated with plaque numbers and cognition status. We also found an increase in TNF-α in MCI brains. In vitro study revealed that TNF-α rather than other cytokines can up-regulate BACE1 protein expression. These findings suggest that BACE1 increase occurs early in MCI and is possibly induced by TNF-α and that BACE1 enzymatic activity may be important for conversion of MCI to AD.

The Impact of Depression on Detrimental Changes in Bone Microstructure in Female Mice.

Background: Several clinical studies have examined the connection between depression and bone loss, but the cause-and-effect relationship between the two conditions, especially in animal models, is not well-studied. Methods: A total of 32 female mice were, randomly divided into control group (CON, n=19) and depression group (DEP, n=13). The mice in the DEP group were subjected to 21 consecutive days of restraint stress, following depressive-like behaviors were assessment. The femurs were collected using Micro-Computed Tomography (µCT) and histochemical staining. In parallel, levels of serotonin-related proteins in the brain were measured using Western blot analysis, and sex hormone profiles were determined through liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). Results: The mice in the DEP group exhibited clear signs of depressive-like behaviors and an increase in serotonin transporter levels (t=-2.435, P< 0.05). In comparison to the CON mice, the DEP mice showed a decrease in bone mineral density (t =3.741, P< 0.05), bone surface area density (t =8.009, P<0.01), percent bone volume (t =4.293, P< 0.05), trabecular number (t =5.844, P<0.01), and connected density (t =11.000, P< 0.05). Additionally, there was an increase in trabecular separation (t =-7.436, P<0.01) in DEP mice. Furthermore, the DEP mice displayed a significant reduction in serum estrogen levels (t =4.340, P< 0.05) and changes in its metabolite (t =-3.325, P< 0.05), while the levels of androgens remained unchanged. Conclusion: The restraint stress not only led to the development of depressive-like behaviors but also disrupted the estrogen metabolism pathway, resulting in damage to bone mass and microstructure in female mice. These findings suggest that stress-induced depression may pose a risk for bone loss in female mice by altering estrogen metabolism pathways.