Genome-Wide Association Transethnic Meta-Analyses Identifies Novel Associations Regulating Coagulation Factor VIII and von Willebrand Factor Plasma Levels.

BACKGROUND: Factor VIII (FVIII) and its carrier protein von Willebrand factor (VWF) are associated with risk of arterial and venous thrombosis and with hemorrhagic disorders. We aimed to identify and functionally test novel genetic associations regulating plasma FVIII and VWF. METHODS: We meta-analyzed genome-wide association results from 46 354 individuals of European, African, East Asian, and Hispanic ancestry. All studies performed linear regression analysis using an additive genetic model and associated ≈35 million imputed variants with natural log-transformed phenotype levels. In vitro gene silencing in cultured endothelial cells was performed for candidate genes to provide additional evidence on association and function. Two-sample Mendelian randomization analyses were applied to test the causal role of FVIII and VWF plasma levels on the risk of arterial and venous thrombotic events. RESULTS: We identified 13 novel genome-wide significant ( P≤2.5×10-8) associations, 7 with FVIII levels ( FCHO2/TMEM171/TNPO1, HLA, SOX17/RP1, LINC00583/NFIB, RAB5C-KAT2A, RPL3/TAB1/SYNGR1, and ARSA) and 11 with VWF levels ( PDHB/PXK/KCTD6, SLC39A8, FCHO2/TMEM171/TNPO1, HLA, GIMAP7/GIMAP4, OR13C5/NIPSNAP, DAB2IP, C2CD4B, RAB5C-KAT2A, TAB1/SYNGR1, and ARSA), beyond 10 previously reported associations with these phenotypes. Functional validation provided further evidence of association for all loci on VWF except ARSA and DAB2IP. Mendelian randomization suggested causal effects of plasma FVIII activity levels on venous thrombosis and coronary artery disease risk and plasma VWF levels on ischemic stroke risk. CONCLUSIONS: The meta-analysis identified 13 novel genetic loci regulating FVIII and VWF plasma levels, 10 of which we validated functionally. We provide some evidence for a causal role of these proteins in thrombotic events.

Acetylcholine Inhibits Platelet Activation.

Platelets are key mediators of thrombosis. Many agonists of platelet activation are known, but fewer endogenous inhibitors of platelets, such as prostacyclin and nitric oxide (NO), have been identified. Acetylcholinesterase inhibitors, such as donepezil, can cause bleeding in patients, but the underlying mechanisms are not well understood. We hypothesized that acetylcholine is an endogenous inhibitor of platelets. We measured the effect of acetylcholine or analogs of acetylcholine on human platelet activation ex vivo. Acetylcholine and analogs of acetylcholine inhibited platelet activation, as measured by P-selectin translocation and glycoprotein IIb IIIa conformational changes. Conversely, we found that antagonists of the acetylcholine receptor, such as pancuronium, enhance platelet activation. Furthermore, drugs inhibiting acetylcholinesterase, such as donepezil, also inhibit platelet activation, suggesting that platelets release acetylcholine. We found that NO mediates acetylcholine inhibition of platelets. Our data suggest that acetylcholine is an endogenous inhibitor of platelet activation. The cholinergic system may be a novel target for antithrombotic therapies.

Novel Thrombotic Function of a Human SNP in STXBP5 Revealed by CRISPR/Cas9 Gene Editing in Mice.

OBJECTIVE: To identify and characterize the effect of a SNP (single-nucleotide polymorphism) in the STXBP5 locus that is associated with altered thrombosis in humans. GWAS (genome-wide association studies) have identified numerous SNPs associated with human thrombotic phenotypes, but determining the functional significance of an individual candidate SNP can be challenging, particularly when in vivo modeling is required. Recent GWAS led to the discovery of STXBP5 as a regulator of platelet secretion in humans. Further clinical studies have identified genetic variants of STXBP5 that are linked to altered plasma von Willebrand factor levels and thrombosis in humans, but the functional significance of these variants in STXBP5 is not understood. APPROACH AND RESULTS: We used CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated 9) techniques to produce a precise mouse model carrying a human coding SNP rs1039084 (encoding human p. N436S) in the STXBP5 locus associated with decreased thrombosis. Mice carrying the orthologous human mutation (encoding p. N437S in mouse STXBP5) have lower plasma von Willebrand factor levels, decreased thrombosis, and decreased platelet secretion compared with wild-type mice. This thrombosis phenotype recapitulates the phenotype of humans carrying the minor allele of rs1039084. Decreased plasma von Willebrand factor and platelet activation may partially explain the decreased thrombotic phenotype in mutant mice. CONCLUSIONS: Using precise mammalian genome editing, we have identified a human nonsynonymous SNP rs1039084 in the STXBP5 locus as a causal variant for a decreased thrombotic phenotype. CRISPR/Cas9 genetic editing facilitates the rapid and efficient generation of animals to study the function of human genetic variation in vascular diseases.

Chronic neuron- and age-selective down-regulation of TNF receptor expression in triple-transgenic Alzheimer disease mice leads to significant modulation of amyloid- and Tau-related pathologies.

Neuroinflammation, through production of proinflammatory molecules and activated glial cells, is implicated in Alzheimer's disease (AD) pathogenesis. One such proinflammatory mediator is tumor necrosis factor α (TNF-α), a multifunctional cytokine produced in excess and associated with amyloid ß-driven inflammation and cognitive decline. Long-term global inhibition of TNF receptor type I (TNF-RI) and TNF-RII signaling without cell or stage specificity in triple-transgenic AD mice exacerbates hallmark amyloid and neurofibrillary tangle pathology. These observations revealed that long-term pan anti-TNF-α inhibition accelerates disease, cautions against long-term use of anti-TNF-α therapeutics for AD, and urges more selective regulation of TNF signaling. We used adeno-associated virus vector-delivered siRNAs to selectively knock down neuronal TNF-R signaling. We demonstrate divergent roles for neuronal TNF-RI and TNF-RII where loss of opposing TNF-RII leads to TNF-RI-mediated exacerbation of amyloid ß and Tau pathology in aged triple-transgenic AD mice. Dampening of TNF-RII or TNF-RI+RII leads to a stage-independent increase in Iba-1-positive microglial staining, implying that neuronal TNF-RII may act nonautonomously on the microglial cell population. These results reveal that TNF-R signaling is complex, and it is unlikely that all cells and both receptors will respond positively to broad anti-TNF-α treatments at various stages of disease. In aggregate, these data further support the development of cell-, stage-, and/or receptor-specific anti-TNF-α therapeutics for AD.

Ablation of TNF-RI/RII expression in Alzheimer's disease mice leads to an unexpected enhancement of pathology: implications for chronic pan-TNF-α suppressive therapeutic strategies in the brain.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by severe memory loss and cognitive impairment. Neuroinflammation, including the extensive production of pro-inflammatory molecules and the activation of microglia, has been implicated in the disease process. Tumor necrosis factor (TNF)-α, a prototypic pro-inflammatory cytokine, is elevated in AD, is neurotoxic, and colocalizes with amyloid plaques in AD animal models and human brains. We previously demonstrated that the expression of TNF-α is increased in AD mice at ages preceding the development of hallmark amyloid and tau pathological features and that long-term expression of this cytokine in these mice leads to marked neuronal death. Such observations suggest that TNF-α signaling promotes AD pathogenesis and that therapeutics suppressing this cytokine's activity may be beneficial. To dissect TNF-α receptor signaling requirements in AD, we generated triple-transgenic AD mice (3xTg-AD) lacking both TNF-α receptor 1 (TNF-RI) and 2 (TNF-RII), 3xTg-ADxTNF-RI/RII knock out, the cognate receptors of TNF-α. These mice exhibit enhanced amyloid and tau-related pathological features by the age of 15 months, in stark contrast to age-matched 3xTg-AD counterparts. Moreover, 3xTg-ADxTNF-RI/RII knock out-derived primary microglia reveal reduced amyloid-ß phagocytic marker expression and phagocytosis activity, indicating that intact TNF-α receptor signaling is critical for microglial-mediated uptake of extracellular amyloid-ß peptide pools. Overall, our results demonstrate that globally ablated TNF receptor signaling exacerbates pathogenesis and argues against long-term use of pan-anti-TNF-α inhibitors for the treatment of AD.

Early oligodendrocyte/myelin pathology in Alzheimer's disease mice constitutes a novel therapeutic target.

The detection of myelin disruptions in Alzheimer's disease (AD)-affected brain raises the possibility that oligodendrocytes undergo pathophysiological assault over the protracted course of this neurodegenerative disease. Oligodendrocyte compromise arising from direct toxic effects imparted by pathological amyloid-beta peptides and/or through signals derived from degenerating neurons could play an important role in the disease process. We previously demonstrated that 3xTg-AD mice, which harbor the human amyloid precursor protein Swedish mutant transgene, presenilin knock-in mutation, and tau P301L mutant transgene, exhibit significant alterations in overall myelination patterns and oligodendrocyte status at time points preceding the appearance of amyloid and tau pathology. Herein, we demonstrate that Abeta(1-42) leads to increased caspase-3 expression and apoptotic cell death of both nondifferentiated and differentiated mouse oligodendrocyte precursor (mOP) cells in vitro. Through use of a recombinant adeno-associated virus serotype-2 (rAAV2) vector expressing an Abeta(1-42)-specific intracellular antibody (intrabody), oligodendrocyte and myelin marker expression, as well as myelin integrity, were restored in the vector-infused brain regions of 3xTg-AD mice. Overall, this work provides further insights into the impact of Abeta(1-42)-mediated toxicity on the temporal and spatial progression of subtle myelin disruption during the early presymptomatic stages of AD and may help to validate new therapeutic options designed to avert these early impairments.

Abeta-directed single-chain antibody delivery via a serotype-1 AAV vector improves learning behavior and pathology in Alzheimer's disease mice.

Alzheimer's disease (AD) is a progressive dementing disorder characterized by age-related amyloid-beta (Abeta) deposition, neurofibrillary tangles, and synapse and neuronal loss. It is widely recognized that Abeta is a principal pathogenic mediator of AD. Our goal was to develop an immunotherapeutic approach, which would specifically lead to the clearance and/or neutralization of Abeta in the triple transgenic mouse model (3xTg-AD). These mice develop the amyloid and tangle pathologies and synaptic dysfunction reminiscent of human AD. Using a human single-chain variable fragment (scFv) antibody phage display library, a novel scFv antibody specific to Abeta was isolated, its activity characterized in vitro, and its open reading frame subsequently cloned into a recombinant adeno-associated virus (rAAV) vector. Three-month-old 3xTg-AD mice were intrahippocampally infused with serotype-1 rAAV vectors encoding Abeta-scFv or a control vector using convection-enhanced delivery (CED). Mice receiving rAAV1-Abeta-scFv harbored lower levels of insoluble Abeta and hyperphosphorylated tau, and exhibited improved cognitive function as measured by the Morris Water Maze (MWM) spatial memory task. These results underscore the potential of gene-based passive vaccination for AD, and provide further rationale for the development of Abeta-targeting strategies for this debilitating disease.

Interferon-{gamma} differentially affects Alzheimer's disease pathologies and induces neurogenesis in triple transgenic-AD mice.

Inflammatory processes, including the episodic and/ or chronic elaboration of cytokines, have been identified as playing key roles in a number of neurological disorders. Whether these activities impart a disease-resolving and/or contributory outcome depends at least in part on the disease context, stage of pathogenesis, and cellular milieu in which these factors are released. Interferon-gamma (IFNgamma) is one such cytokine that produces pleiotropic effects in the brain. It is protective by ensuring maintenance of virus latency after infection, yet deleterious by recruiting and activating microglia that secrete potentially damaging factors at sites of brain injury. Using the triple-transgenic mouse model of Alzheimer's disease (3xTg-AD), which develops amyloid and tau pathologies in a pattern reminiscent of human Alzheimer's disease, we initiated chronic intrahippocampal expression of IFNgamma through delivery of a serotype-1 recombinant adeno-associated virus vector (rAAV1-IFNgamma). Ten months of IFNgamma expression led to an increase in microglial activation, steady-state levels of proinflammatory cytokine and chemokine transcripts, and severity of amyloid-related pathology. In contrast, these rAAV1-IFNgamma-treated 3xTg-AD mice also exhibited diminished phospho-tau pathology and evidence of increased neurogenesis. Overall, IFNgamma mediates what seem to be diametrically opposed functions in the setting of AD-related neurodegeneration. Gaining an understanding as to how these apparently divergent functions are interrelated and controlled could elucidate new therapeutic strategies designed to harness the neuroprotective activity of IFNgamma.

Generating differentially targeted amyloid-beta specific intrabodies as a passive vaccination strategy for Alzheimer's disease.

Amyloid-beta (A beta) has been identified as a key component in Alzheimer's disease (AD). Significant in vitro and human pathological data suggest that intraneuronal accumulation of A beta peptides plays an early role in the neurodegenerative cascade. We hypothesized that targeting an antibody-based therapeutic to specifically abrogate intracellular A beta accumulation could prevent or slow disease onset. A beta 42-specific intracellular antibodies (intrabodies) with and without an intracellular trafficking signal were engineered from a previously characterized single-chain variable fragment (scFv) antibody. The intrabodies, one with an endoplasmic reticulum (ER) targeting signal and one devoid of a targeting sequence, were assessed in cells harboring a doxycycline (Dox)-regulated mutant human amyloid precursor protein Swedish mutant (hAPP(swe)) transcription unit for their abilities to prevent A beta peptide egress. Adeno-associated virus (AAV) vectors expressing the engineered intrabodies were administered to young adult 3xTg-AD mice, a model that develops amyloid and Tau pathologies, prior to the initial appearance of intraneuronal A beta. Chronic expression of the ER-targeted intrabody (IB) led to partial clearance of A beta 42 deposits and interestingly, in reduced staining for a pathologic phospho-Tau epitope (Thr231). This approach may provide insights into the functional relevance of intraneuronal A beta accumulation in early AD and potentially lead to the development of new therapeutics.

The choline transporter Slc44a2 controls platelet activation and thrombosis by regulating mitochondrial function.

Genetic factors contribute to the risk of thrombotic diseases. Recent genome wide association studies have identified genetic loci including SLC44A2 which may regulate thrombosis. Here we show that Slc44a2 controls platelet activation and thrombosis by regulating mitochondrial energetics. We find that Slc44a2 null mice (Slc44a2(KO)) have increased bleeding times and delayed thrombosis compared to wild-type (Slc44a2(WT)) controls. Platelets from Slc44a2(KO) mice have impaired activation in response to thrombin. We discover that Slc44a2 mediates choline transport into mitochondria, where choline metabolism leads to an increase in mitochondrial oxygen consumption and ATP production. Platelets lacking Slc44a2 contain less ATP at rest, release less ATP when activated, and have an activation defect that can be rescued by exogenous ADP. Taken together, our data suggest that mitochondria require choline for maximum function, demonstrate the importance of mitochondrial metabolism to platelet activation, and reveal a mechanism by which Slc44a2 influences thrombosis.

Triple-transgenic Alzheimer's disease mice exhibit region-specific abnormalities in brain myelination patterns prior to appearance of amyloid and tau pathology.

Alzheimer's disease (AD) is a progressively debilitating brain disorder pathologically defined by extracellular amyloid plaques, intraneuronal neurofibrillary tangles, and synaptic disintegrity. AD has not been widely considered a disease of white matter, but more recent evidence suggests the existence of abnormalities in myelination patterns and myelin attrition in AD-afflicted human brains. Herein, we demonstrate that triple-transgenic AD (3xTg-AD) mice, which harbor the human amyloid precursor protein Swedish mutant transgene, presenilin knock-in mutation, and tau P301L mutant transgene, exhibit significant region-specific alterations in myelination patterns and in oligodendrocyte marker expression profiles at time points preceding the appearance of amyloid and tau pathology. These immunohistochemical signatures are coincident with age-related alterations in axonal and myelin sheath ultrastructure as visualized by comparative electron microscopic examination of 3xTg-AD and nontransgenic mouse brain tissue. Overall, these findings indicate that 3xTg-AD mice represent a viable model in which to examine mechanisms underlying AD-related myelination and neural transmission defects that occur early during presymptomatic stages of the disease process.

Chronic neuron-specific tumor necrosis factor-alpha expression enhances the local inflammatory environment ultimately leading to neuronal death in 3xTg-AD mice.

Inflammatory mediators, such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta, appear integral in initiating and/or propagating Alzheimer's disease (AD)-associated pathogenesis. We have previously observed a significant increase in the number of mRNA transcripts encoding the pro-inflammatory cytokine TNF-alpha, which correlated to regionally enhanced microglial activation in the brains of triple transgenic mice (3xTg-AD) before the onset of overt amyloid pathology. In this study, we reveal that neurons serve as significant sources of TNF-alpha in 3xTg-AD mice. To further define the role of neuronally derived TNF-alpha during early AD-like pathology, a recombinant adeno-associated virus vector expressing TNF-alpha was stereotactically delivered to 2-month-old 3xTg-AD mice and non-transgenic control mice to produce sustained focal cytokine expression. At 6 months of age, 3xTg-AD mice exhibited evidence of enhanced intracellular levels of amyloid-beta and hyperphosphorylated tau, as well as microglial activation. At 12 months of age, both TNF receptor II and Jun-related mRNA levels were significantly enhanced, and peripheral cell infiltration and neuronal death were observed in 3xTg-AD mice, but not in non-transgenic mice. These data indicate that a pathological interaction exists between TNF-alpha and the AD-related transgene products in the brains of 3xTg-AD mice. Results presented here suggest that chronic neuronal TNF-alpha expression promotes inflammation and, ultimately, neuronal cell death in this AD mouse model, advocating the development of TNF-alpha-specific agents to subvert AD.

Reduced pathology and improved behavioral performance in Alzheimer's disease mice vaccinated with HSV amplicons expressing amyloid-beta and interleukin-4.

Immunotherapeutics designed to dissolve existing amyloid plaques or to interrupt amyloid-beta (Abeta) accumulation may be feasible for treatment and/or prevention of Alzheimer's disease (AD). "Shaping" the immune responses elicited against Abeta is requisite toward generating an efficacious and safe outcome; this can be achieved by minimizing the possibility of deleterious inflammatory reactions in the brain as observed in clinical testing of Abeta peptide/adjuvant-based modalities. Herpes simplex virus (HSV)-based amplicons can coexpress multiple antigens and/or immunomodulatory genes due to their large genetic size capacity, thereby facilitating antigen-specific immune response shaping. We have constructed an amplicon (HSV(IE)Abeta(CMV)IL-4) that co-delivers Abeta(1-42) with interleukin-4 (IL-4), a cytokine that promotes the generation of Th2-like T-cell responses, which are favored in the setting of AD immunotherapy. Triple-transgenic AD (3xTg-AD) mice, which progressively develop both amyloid and neurofibrillary tangle pathology, were vaccinated thrice with HSV(IE)Abeta(CMV)IL-4, or a set of control amplicon vectors. Increased Th2-related, Abeta-specific antibodies, improved learning and functioning of memory, and prevention of AD-related amyloid and tau pathological progression were observed significantly more in the HSV(IE)Abeta(CMV)IL-4 vaccinated mice as compared to the other experimental groups. Our study underscores the potential of Abeta immunotherapy for AD and highlights the potency of amplicons in facilitating the immune response modulation to a disease-relevant antigen.

Reduced Pathology and Improved Behavioral Performance in Alzheimer's Disease Mice Vaccinated With HSV Amplicons Expressing Amyloid-ß and Interleukin-4.

Immunotherapeutics designed to dissolve existing amyloid plaques or to interrupt amyloid-ß (Aß) accumulation may be feasible for treatment and/or prevention of Alzheimer's disease (AD). "Shaping" the immune responses elicited against Aß is requisite toward generating an efficacious and safe outcome; this can be achieved by minimizing the possibility of deleterious inflammatory reactions in the brain as observed in clinical testing of Aß peptide/adjuvant-based modalities. Herpes simplex virus (HSV)-based amplicons can coexpress multiple antigens and/or immunomodulatory genes due to their large genetic size capacity, thereby facilitating antigen-specific immune response shaping. We have constructed an amplicon (HSVIEAßCMVIL-4) that co-delivers Aß1-42with interleukin-4 (IL-4), a cytokine that promotes the generation of Th2-like T-cell responses, which are favored in the setting of AD immunotherapy. Triple-transgenic AD (3xTg-AD) mice, which progressively develop both amyloid and neurofibrillary tangle pathology, were vaccinated thrice with HSVIEAßCMVIL-4, or a set of control amplicon vectors. Increased Th2-related, Aß-specific antibodies, improved learning and functioning of memory, and prevention of AD-related amyloid and tau pathological progression were observed significantly more in the HSVIEAßCMVIL-4 vaccinated mice as compared to the other experimental groups. Our study underscores the potential of Aß immunotherapy for AD and highlights the potency of amplicons in facilitating the immune response modulation to a disease-relevant antigen.

Detailed immunohistochemical characterization of temporal and spatial progression of Alzheimer's disease-related pathologies in male triple-transgenic mice.

BACKGROUND: Several transgenic animal models genetically predisposed to develop Alzheimer's disease (AD)-like pathology have been engineered to facilitate the study of disease pathophysiology and the vetting of potential disease-modifying therapeutics. The triple transgenic mouse model of AD (3xTg-AD) harbors three AD-related genetic loci: human PS1M146V, human APPswe, and human tauP301L. These mice develop both amyloid plaques and neurofibrillary tangle-like pathology in a progressive and age-dependent manner, while these pathological hallmarks are predominantly restricted to the hippocampus, amygdala, and the cerebral cortex the main foci of AD neuropathology in humans. This model represents, at present, one of the most advanced preclinical tools available and is being employed ever increasingly in the study of mechanisms underlying AD, yet a detailed regional and temporal assessment of the subtleties of disease-related pathologies has not been reported. METHODS AND RESULTS: In this study, we immunohistochemically documented the evolution of AD-related transgene expression, amyloid deposition, tau phosphorylation, astrogliosis, and microglial activation throughout the hippocampus, entorhinal cortex, primary motor cortex, and amygdala over a 26-month period in male 3xTg-AD mice. Intracellular amyloid-beta accumulation is detectable the earliest of AD-related pathologies, followed temporally by phospho-tau, extracellular amyloid-beta, and finally paired helical filament pathology. Pathology appears to be most severe in medial and caudal hippocampus. While astrocytic staining remains relatively constant at all ages and regions assessed, microglial activation appears to progressively increase temporally, especially within the hippocampal formation. CONCLUSION: These data fulfill an unmet need in the ever-widening community of investigators studying 3xTg-AD mice and provide a foundation upon which to design future experiments that seek to examine stage-specific disease mechanisms and/or novel therapeutic interventions for AD.

Interleukin-17 limits hypoxia-inducible factor 1α and development of hypoxic granulomas during tuberculosis.

Mycobacterium tuberculosis (Mtb) is a global health threat, compounded by the emergence of drug-resistant strains. A hallmark of pulmonary tuberculosis (TB) is the formation of hypoxic necrotic granulomas, which upon disintegration, release infectious Mtb. Furthermore, hypoxic necrotic granulomas are associated with increased disease severity and provide a niche for drug-resistant Mtb. However, the host immune responses that promote the development of hypoxic TB granulomas are not well described. Using a necrotic Mtb mouse model, we show that loss of Mtb virulence factors, such as phenolic glycolipids, decreases the production of the proinflammatory cytokine IL-17 (also referred to as IL-17A). IL-17 production negatively regulates the development of hypoxic TB granulomas by limiting the expression of the transcription factor hypoxia-inducible factor 1α (HIF1α). In human TB patients, HIF1α mRNA expression is increased. Through genotyping and association analyses in human samples, we identified a link between the single nucleotide polymorphism rs2275913 in the IL-17 promoter (-197G/G), which is associated with decreased IL-17 production upon stimulation with Mtb cell wall. Together, our data highlight a potentially novel role for IL-17 in limiting the development of hypoxic necrotic granulomas and reducing disease severity in TB.

SIRT6 protects against endothelial dysfunction and atherosclerosis in mice.

SIRT6 is an important member of sirtuin family that represses inflammation, aging and DNA damage, three of which are causing factors for endothelial dysfunction. SIRT6 expression is decreased in atherosclerotic lesions from ApoE(-/-) mice and human patients. However, the role of SIRT6 in regulating vascular endothelial function and atherosclerosis is not well understood. Here we show that SIRT6 protects against endothelial dysfunction and atherosclerosis. Global and endothelium-specific SIRT6 knockout mice exhibited impaired endothelium-dependent vasorelaxation. Moreover, SIRT6(+/-) haploinsufficient mice fed a high-fat diet (HFD) also displayed impaired endothelium-dependent vasorelaxation. Importantly, SIRT6(+/-); ApoE(-/-) mice after HFD feeding exhibited exacerbated atherosclerotic lesion development, concurrent with increased expression of the proinflammatory cytokine VCAM-1. Loss- and gain-of-SIRT6 function studies in cultured human endothelial cells (ECs) showed that SIRT6 attenuated monocyte adhesion to ECs. RNA-sequencing profiling revealed that SIRT6 overexpression decreased the expression of multiple atherosclerosis-related genes, including proatherogenic gene TNFSF4 (tumor necrosis factor superfamily member 4). Chromatin immunoprecipitation assays showed that SIRT6 decreased TNFSF4 gene expression by binding to and deacetylating H3K9 at TNFSF4 gene promoter. Collectively, these findings demonstrate that SIRT6 play a pivotal role in maintaining endothelial function and increased SIRT6 activity could be a new therapeutic strategy to combat atherosclerotic disease.

HSV amplicon-mediated Abeta vaccination in Tg2576 mice: differential antigen-specific immune responses.

Given the participation of amyloid beta (Abeta) in Alzheimer's disease (AD) pathogenesis the derivation of experimental therapeutics to prevent Abeta fibrillogenesis and/or enhance removal of parenchymal amyloid deposits represent viable disease-modifying approaches. Active Abeta-based immunotherapies have shown promise in mouse AD models, but application in human trials was accompanied by moderate brain inflammation in a subset of patients. Immune-shaping vaccine platforms may mitigate adverse effects. Herein, we describe the use of herpes simplex virus (HSV)-derived amplicons to elicit distinctive immune responses against Abeta. Two vaccine vectors were constructed: one expressing Abeta1-42 alone (HSVAbeta), and a second expressing Abeta1-42 fused with the molecular adjuvant tetanus toxin Fragment C (HSVAbeta/TtxFC). Peripheral administration of these vaccines augmented humoral responses to Abeta and reduced CNS Abeta deposition in Tg2576 AD mice. Interestingly and unexpectedly, HSVAbeta vaccination was uniquely toxic and incited the expression of pro-inflammatory molecule transcripts within the hippocampi of Tg2576 mice, suggesting that this paradigm may serve as a relevant model to study Abeta vaccine-elicited CNS inflammatory syndromes.

Early correlation of microglial activation with enhanced tumor necrosis factor-alpha and monocyte chemoattractant protein-1 expression specifically within the entorhinal cortex of triple transgenic Alzheimer's disease mice.

BACKGROUND: Alzheimer's disease is a complex neurodegenerative disorder characterized pathologically by a temporal and spatial progression of beta-amyloid (Abeta) deposition, neurofibrillary tangle formation, and synaptic degeneration. Inflammatory processes have been implicated in initiating and/or propagating AD-associated pathology within the brain, as inflammatory cytokine expression and other markers of inflammation are pronounced in individuals with AD pathology. The current study examines whether inflammatory processes are evident early in the disease process in the 3xTg-AD mouse model and if regional differences in inflammatory profiles exist. METHODS: Coronal brain sections were used to identify Abeta in 2, 3, and 6-month 3xTg-AD and non-transgenic control mice. Quantitative real-time RT-PCR was performed on microdissected entorhinal cortex and hippocampus tissue of 2, 3, and 6-month 3xTg-AD and non-transgenic mice. Microglial/macrophage cell numbers were quantified using unbiased stereology in 3xTg-AD and non-transgenic entorhinal cortex and hippocampus containing sections. RESULTS: We observed human Abeta deposition at 3 months in 3xTg-AD mice which is enhanced by 6 months of age. Interestingly, we observed a 14.8-fold up-regulation of TNF-alpha and 10.8-fold up-regulation of MCP-1 in the entorhinal cortex of 3xTg-AD mice but no change was detected over time in the hippocampus or in either region of non-transgenic mice. Additionally, this increase correlated with a specific increase in F4/80-positive microglia and macrophages in 3xTg-AD entorhinal cortex. CONCLUSION: Our data provide evidence for early induction of inflammatory processes in a model that develops amyloid and neurofibrillary tangle pathology. Additionally, our results link inflammatory processes within the entorhinal cortex, which represents one of the earliest AD-affected brain regions.

Biochemical and morphological characterization of the AßPP/PS/tau triple transgenic mouse model and its relevance to sporadic Alzheimer's disease.

Transgenic (Tg) mouse models of Alzheimer's disease (AD) have been genetically altered with human familial AD genes driven by powerful promoters. However, a Tg model must accurately mirror the pathogenesis of the human disease, not merely the signature amyloid and/or tau pathology, as such hallmarks can arise via multiple convergent or even by pathogenic mechanisms unrelated to human sporadic AD. The 3 × Tg-AD mouse simultaneously expresses 3 rare familial mutant genes that in humans independently produce devastating amyloid-ß protein precursor (AßPP), presenilin-1, and frontotemporal dementias; hence, technically speaking, these mice are not a model of sporadic AD, but are informative in assessing co-evolving amyloid and tau pathologies. While end-stage amyloid and tau pathologies in 3 × Tg-AD mice are similar to those observed in sporadic AD, the pathophysiological mechanisms leading to these lesions are quite different. Comprehensive biochemical and morphological characterizations are important to gauge the predictive value of Tg mice. Investigation of AßPP, amyloid-ß (Aß), and tau in the 3 × Tg-AD model demonstrates AD-like pathology with some key differences compared to human sporadic AD. The biochemical dissection of AßPP reveals different cleavage patterns of the C-terminus of AßPP when compared to human AD, suggesting divergent pathogenic mechanisms. Human tau is concomitantly expressed with AßPP/Aß from an early age while abundant extracellular amyloid plaques and paired helical filaments are manifested from 18 months on. Understanding the strengths and limitations of Tg mouse AD models through rigorous biochemical, pathological, and functional analyses will facilitate the derivation of models that better approximate human sporadic AD.