Repeated Administration of 2-Hydroxypropyl-ß-Cyclodextrin (HPßCD) Attenuates the Chronic Inflammatory Response to Experimental Stroke.

Globally, more than 67 million people are living with the effects of ischemic stroke. Importantly, many stroke survivors develop a chronic inflammatory response that may contribute to cognitive impairment, a common and debilitating sequela of stroke that is insufficiently studied and currently untreatable. 2-Hydroxypropyl-ß-cyclodextrin (HPßCD) is an FDA-approved cyclic oligosaccharide that can solubilize and entrap lipophilic substances. The goal of the present study was to determine whether the repeated administration of HPßCD curtails the chronic inflammatory response to stroke by reducing lipid accumulation within stroke infarcts in a distal middle cerebral artery occlusion mouse model of stroke. To achieve this goal, we subcutaneously injected young adult and aged male mice with vehicle or HPßCD 3 times per week, with treatment beginning 1 week after stroke. We evaluated mice at 7 weeks following stroke using immunostaining, RNA sequencing, lipidomic, and behavioral analyses. Chronic stroke infarct and peri-infarct regions of HPßCD-treated mice were characterized by an upregulation of genes involved in lipid metabolism and a downregulation of genes involved in innate and adaptive immunity, reactive astrogliosis, and chemotaxis. Correspondingly, HPßCD reduced the accumulation of lipid droplets, T lymphocytes, B lymphocytes, and plasma cells in stroke infarcts. Repeated administration of HPßCD also preserved NeuN immunoreactivity in the striatum and thalamus and c-Fos immunoreactivity in hippocampal regions. Additionally, HPßCD improved recovery through the protection of hippocampal-dependent spatial working memory and reduction of impulsivity. These results indicate that systemic HPßCD treatment following stroke attenuates chronic inflammation and secondary neurodegeneration and prevents poststroke cognitive decline.SIGNIFICANCE STATEMENT Dementia is a common and debilitating sequela of stroke. Currently, there are no available treatments for poststroke dementia. Our study shows that lipid metabolism is disrupted in chronic stroke infarcts, which causes an accumulation of uncleared lipid debris and correlates with a chronic inflammatory response. To our knowledge, these substantial changes in lipid homeostasis have not been previously recognized or investigated in the context of ischemic stroke. We also provide a proof of principle that solubilizing and entrapping lipophilic substances using HPßCD could be an effective strategy for treating chronic inflammation after stroke and other CNS injuries. We propose that using HPßCD for the prevention of poststroke dementia could improve recovery and increase long-term quality of life in stroke sufferers.

Post-Stroke Administration of the p75 Neurotrophin Receptor Modulator, LM11A-31, Attenuates Chronic Changes in Brain Metabolism, Increases Neurotransmitter Levels, and Improves Recovery.

The aim of this study was to test whether poststroke oral administration of a small molecule p75 neurotrophin receptor (p75NTR) modulator (LM11A-31) can augment neuronal survival and improve recovery in a mouse model of stroke. Mice were administered LM11A-31 for up to 12 weeks, beginning 1 week after stroke. Metabolomic analysis revealed that after 2 weeks of daily treatment, mice that received LM11A-31 were distinct from vehicle-treated mice by principal component analysis and had higher levels of serotonin, acetylcholine, and dopamine in their ipsilateral hemisphere. LM11A-31 treatment also improved redox homeostasis by restoring reduced glutathione. It also offset a stroke-induced reduction in glycolysis by increasing acetyl-CoA. There was no effect on cytokine levels in the infarct. At 13 weeks after stroke, adaptive immune cell infiltration in the infarct was unchanged in LM11A-31-treated mice, indicating that LM11A-31 does not alter the chronic inflammatory response to stroke at the site of the infarct. However, LM11A-31-treated mice had less brain atrophy, neurodegeneration, tau pathology, and microglial activation in other regions of the ipsilateral hemisphere. These findings correlated with improved recovery of motor function on a ladder test, improved sensorimotor and cognitive abilities on a nest construction test, and less impulsivity in an open field test. These data support small molecule modulation of the p75NTR for preserving neuronal health and function during stroke recovery. SIGNIFICANCE STATEMENT: The findings from this study introduce the p75 neurotrophin receptor as a novel small molecule target for promotion of stroke recovery. Given that LM11A-31 is in clinical trials as a potential therapy for Alzheimer's disease, it could be considered as a candidate for assessment in stroke or vascular dementia studies.

IgA natural antibodies are produced following T-cell independent B-cell activation following stroke.

Up to 30% of stroke patients experience cognitive decline within one year of their stroke. There are currently no FDA-approved drugs that can prevent post-stroke cognitive decline, in part due to a poor understanding of the mechanisms involved. We have previously demonstrated that a B-lymphocyte response to stroke, marked by IgA + cells, can cause delayed cognitive dysfunction in mice and that a similar adaptive immune response occurs in the brains of some human stroke patients that suffer from vascular dementia. The stimuli which trigger B-lymphocyte activation following stroke, and their target antigens, are still unknown. Therefore, to learn more about the mechanisms by which B-lymphocytes become activated following stroke we first characterized the temporal kinetics of the B-lymphocyte, T-lymphocyte, and plasma cell (PC) response to stroke in the brain by immunohistochemistry (IHC). We discovered that B-lymphocyte, T-lymphocyte, and plasma cell infiltration within the infarct progressively increases between 2 and 7 weeks after stroke. We then compared the B-lymphocyte response to stroke in WT, MHCII-/-, CD4-/-, and MyD88-/- mice to determine if B-lymphocytes mature into IgA + PCs through a T-lymphocyte and MyD88 dependent mechanism. Our data from a combination of IHC and flow cytometry indicate that following stroke, a population of IgA + PCs develops independently of CD4 + helper T-lymphocytes and MyD88 signaling. Subsequent sequencing of immunoglobulin genes of individual IgA + PCs present within the infarct identified a novel population of natural antibodies with few somatic mutations in complementarity-determining regions. These findings indicate that a population of IgA + PCs develops in the infarct following stroke by B-lymphocytes interacting with one or more thymus independent type 2 (TI-2) antigens, and that they produce IgA natural antibodies.

Genetic reduction of Nrf2 exacerbates cognitive deficits in a mouse model of Alzheimer's disease.

Aging is the major risk factor for several neurodegenerative diseases, including Alzheimer's disease (AD). However, the mechanisms by which aging contributes to neurodegeneration remain elusive. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is a transcription factor that regulates expression of a vast number of genes by binding to the antioxidant response element. Nrf2 levels decrease as a function of age, and reduced Nrf2 levels have been reported in postmortem human brains and animal models of AD. Nevertheless, it is still unknown whether Nrf2 plays a role in the cognitive deficits associated with AD. To address this question, we used a genetic approach to remove the Nrf2 gene from APP/PS1 mice, a widely used animal model of AD. We found that the lack of Nrf2 significantly exacerbates cognitive deficits in APP/PS1, without altering gross motor function. Specifically, we found an exacerbation of deficits in spatial learning and memory, as well as in working and associative memory. Different brain regions control these behavioral tests, indicating that the lack of Nrf2 has a global effect on brain function. The changes in cognition were linked to an increase in Aß and interferon-gamma (IFNγ) levels, and microgliosis. The changes in IFNγ levels are noteworthy as previously published evidence indicates that IFNγ can increase microglia activation and induce Aß production. Our data suggest a clear link between Nrf2 and AD-mediated cognitive decline and further strengthen the connection between Nrf2 and AD.

Glial scars are permeable to the neurotoxic environment of chronic stroke infarcts.

Following stroke, the damaged tissue undergoes liquefactive necrosis, a stage of infarct resolution that lasts for months although the exact length of time is currently unknown. One method of repair involves reactive astrocytes and microglia forming a glial scar to compartmentalize the area of liquefactive necrosis from the rest of the brain. The formation of the glial scar is a critical component of the healing response to stroke, as well as other central nervous system (CNS) injuries. The goal of this study was to evaluate the toxicity of the extracellular fluid present in areas of liquefactive necrosis and determine how effectively it is segregated from the remainder of the brain. To accomplish this goal, we used a mouse model of stroke in conjunction with an extracellular fluid toxicity assay, fluorescent and electron microscopy, immunostaining, tracer injections into the infarct, and multiplex immunoassays. We confirmed that the extracellular fluid present in areas of liquefactive necrosis following stroke is toxic to primary cortical and hippocampal neurons for at least 7 weeks following stroke, and discovered that although glial scars are robust physical and endocytic barriers, they are nevertheless permeable. We found that molecules present in the area of liquefactive necrosis can leak across the glial scar and are removed by a combination of paravascular clearance and microglial endocytosis in the adjacent tissue. Despite these mechanisms, there is delayed atrophy, cytotoxic edema, and neuron loss in regions adjacent to the infarct for weeks following stroke. These findings suggest that one mechanism of neurodegeneration following stroke is the failure of glial scars to impermeably segregate areas of liquefactive necrosis from surviving brain tissue.

B-lymphocyte-mediated delayed cognitive impairment following stroke.

Each year, 10 million people worldwide survive the neurologic injury associated with a stroke. Importantly, stroke survivors have more than twice the risk of subsequently developing dementia compared with people who have never had a stroke. The link between stroke and the later development of dementia is not understood. There are reports of oligoclonal bands in the CSF of stroke patients, suggesting that in some people a B-lymphocyte response to stroke may occur in the CNS. Therefore, we tested the hypothesis that a B-lymphocyte response to stroke could contribute to the onset of dementia. We discovered that, in mouse models, activated B-lymphocytes infiltrate infarcted tissue in the weeks after stroke. B-lymphocytes undergo isotype switching, and IgM, IgG, and IgA antibodies are found in the neuropil adjacent to the lesion. Concurrently, mice develop delayed deficits in LTP and cognition. Genetic deficiency, and the pharmacologic ablation of B-lymphocytes using an anti-CD20 antibody, prevents the appearance of delayed cognitive deficits. Furthermore, immunostaining of human postmortem tissue revealed that a B-lymphocyte response to stroke also occurs in the brain of some people with stroke and dementia. These data suggest that some stroke patients may develop a B-lymphocyte response to stroke that contributes to dementia, and is potentially treatable with FDA-approved drugs that target B cells.

County Records for Aedes japonicus in Georgia.

Consolidating and updating distributional data for mosquito species within a state is a good practice. These updates have an immediate impact by providing documented species distribution information for public use and by serving as a resource to researchers who need background information about a species's state distribution. In Georgia, Aedes japonicus, an introduced species, was peer review reported from 7 counties (2002-06): Fulton, Habersham, Lumpkin, Rabun, Towns, Union, and White. No further records were found in peer-reviewed journals or in the Symbiota Collections of Arthropods Network. This study consolidated the 7 peer-reviewed county records for Ae. japonicus with 73 new county records from surveillance data collected by the Georgia Department of Public Health. This study documented the presence of Ae. japonicus in 80 of the 159 counties in Georgia.

Deciding Whether to Take Sacubitril/Valsartan: How Cardiologists and Patients Discuss Out-of-Pocket Costs.

Background Out-of-pocket costs have significant implications for patients with heart failure and should ideally be incorporated into shared decision-making for clinical care. High out-of-pocket cost is one potential reason for the slow uptake of newer guideline-directed medical therapies for heart failure with reduced ejection fraction. This study aims to characterize patient-cardiologist discussions involving out-of-pocket costs associated with sacubitril/valsartan during the early postapproval period. Methods and Results We conducted content analysis on 222 deidentified transcripts of audio-recorded outpatient encounters taking place between 2015 and 2018 in which cardiologists (n=16) and their patients discussed whether to initiate, continue, or discontinue sacubitril/valsartan. In the 222 included encounters, 100 (45%) contained discussions about cost. Cost was discussed in a variety of contexts: when sacubitril/valsartan was initiated, not initiated, continued, and discontinued. Of the 97 cost conversations analyzed, the majority involved isolated discussions about insurance coverage (64/97 encounters; 66%) and few addressed specific out-of-pocket costs or affordability (28/97 encounters; 29%). Discussion of free samples of sacubitril/valsartan was common (52/97 encounters; 54%), often with no discussion of a longer-term plan for addressing cost. Conclusions Although cost conversations were somewhat common in patient-cardiologist encounters in which sacubitril/valsartan was discussed, these conversations were generally superficial, rarely addressing affordability or cost-value judgments. Cardiologists frequently provided patients with a course of free sacubitril/valsartan samples without a plan to address the cost after the samples ran out.

Increased fatty acid metabolism and decreased glycolysis are hallmarks of metabolic reprogramming within microglia in degenerating white matter during recovery from experimental stroke.

The goal of this study was to evaluate changes in metabolic homeostasis during the first 12 weeks of recovery in a distal middle cerebral artery occlusion mouse model of stroke. To achieve this goal, we compared the brain metabolomes of ipsilateral and contralateral hemispheres from aged male mice up to 12 weeks after stroke to that of age-matched naïve and sham mice. There were 707 biochemicals detected in each sample by liquid chromatography-mass spectroscopy (LC-MS). Mitochondrial fatty acid ß-oxidation, indicated by acyl carnitine levels, was increased in stroked tissue at 1 day and 4 weeks following stroke. Glucose and several glycolytic intermediates were elevated in the ipsilateral hemisphere for 12 weeks compared to the aged naïve controls, but pyruvate was decreased. Additionally, itaconate, a glycolysis inhibitor associated with activation of anti-inflammatory mechanisms in myeloid cells, was higher in the same comparisons. Spatial transcriptomics and RNA in situ hybridization localized these alterations to microglia within the area of axonal degeneration. These results indicate that chronic metabolic differences exist between stroked and control brains, including alterations in fatty acid metabolism and glycolysis within microglia in areas of degenerating white matter for at least 12 weeks after stroke.

Aedes aegypti in Georgia, USA.

Aedes aegypti, commonly known as the yellow fever mosquito, is closely linked to the human environment and directly influenced by the availability of water-holding containers for oviposition and larval development. The discovery of an active population of Ae. aegypti in Columbus, GA, was deemed an important public health matter, and extensive surveillance was initiated to monitor, delineate, and suppress this population.

COVID-19 Response Strategies at Large Institutes of Higher Education in the United States: A Landscape Analysis, Fall 2020.

PURPOSE: To examine the pandemic response plans of institutes of higher education (i.e., colleges and universities), including COVID-19 prevention, enforcement, and testing strategies. METHOD: Data from the largest public (n = 50) and private (n = 50) US institutes of higher education were collected from October 30 to November 20, 2020. RESULTS: Most institutes of higher education (n = 93) offered some in-person teaching in the Fall 2020 semester; most adopted masking (100%) and physical distancing (99%) mandates. Other preventive strategies included on-campus housing de-densification (58%), classroom de-densification (61%), mandated COVID-19-related training (39%), and behavioral compacts (43%). Testing strategies included entry testing (65%), testing at regular intervals (32%), population sample testing (46%), and exit testing (15%). More private than public institutes implemented intercollegiate athletics bans, behavioral compacts, and suspension clauses for noncompliance. CONCLUSIONS: Variability in COVID-19 prevention and testing strategies highlights the need for national recommendations and the equitable distribution of sufficient pandemic response resources to institutes of higher education.

The p75 neurotrophin receptor promotes amyloid-beta(1-42)-induced neuritic dystrophy in vitro and in vivo.

Oligomeric forms of amyloid-beta (Abeta) are thought to play a causal role in Alzheimer's disease (AD), and the p75 neurotrophin receptor (p75(NTR)) has been implicated in Abeta-induced neurodegeneration. To further define the functions of p75(NTR) in AD, we examined the interaction of oligomeric Abeta(1-42) with p75(NTR), and the effects of that interaction on neurite integrity in neuron cultures and in a chronic AD mouse model. Atomic force microscopy was used to ascertain the aggregated state of Abeta, and fluorescence resonance energy transfer analysis revealed that Abeta oligomers interact with the extracellular domain of p75(NTR). In vitro studies of Abeta-induced death in neuron cultures isolated from wild-type and p75(NTR-/-) mice, in which the p75(NTR) extracellular domain is deleted, showed reduced sensitivity of mutant cells to Abeta-induced cell death. Interestingly, Abeta-induced neuritic dystrophy and activation of c-Jun, a known mediator of Abeta-induced deleterious signaling, were completely prevented in p75(NTR-/-) neuron cultures. Thy1-hAPP(Lond/Swe) x p75(NTR-/-) mice exhibited significantly diminished hippocampal neuritic dystrophy and complete reversal of basal forebrain cholinergic neurite degeneration relative to those expressing wild-type p75(NTR). Abeta levels were not affected, suggesting that removal of p75(NTR) extracellular domain reduced the ability of excess Abeta to promote neuritic degeneration. These findings indicate that although p75(NTR) likely does not mediate all Abeta effects, it does play a significant role in enabling Abeta-induced neurodegeneration in vitro and in vivo, establishing p75(NTR) as an important therapeutic target for AD.

It's Best to Be Prepared: Lessons Learned from the Past Prepared Georgia for Hurricane Michael.

Onsite assessments for mosquito larval habitat sites are critical after a hurricane makes landfall. Due to lack of forward assessment activities and the uncertain path of Hurricane Irma, it was difficult to determine what areas would be most affected, making it challenging to determine the availability of Department of Public Health Environmental Health Strike Team members from unaffected areas. However, lessons learned from assessing the public health response to Hurricane Irma (2017) helped improve the response to Hurricane Michael (2018).

Integrated mental health screening for obstetric fistula patients in Mali: From evidence to policy.

BACKGROUND: Obstetric fistula significantly impacts women's mental health and well-being. Routine screening for mental health in fistula repair programs can be a gateway to link patients to services, and can produce routine data to inform programmatic investments. This study observed the integration of a mental health screening program into an obstetric fistula repair program in Mali, with two specific objectives: 1) to describe the social and mental health well-being of women presenting with obstetric fistulas in Mali, and 2) to document the impact of the mental health screening pilot on policy change in Mali. METHODS: Seven fistula repair campaigns were conducted between June 2016 and May 2017. All individuals presenting for fistula repair completed a mental health assessment at intake, including a depression screener (PHQ-9) and an assessment of psycho-social impacts of fistula. The depression screener was repeated three months following inpatient discharge. Findings were shared with stakeholders in Mali and impacts on policy were documented. RESULTS: Of 207 women who presented for fistula repair, 167 patients completed the mental health assessment at surgical intake, and 130 patients repeated the screener at 3-month follow-up. At intake, 36.5% of women had moderate or severe depression, decreasing to 16.9% at follow-up. The mean depression score differed significantly by timepoint (9.14 vs. 6.72, p <0.001). Results were shared in a report with stakeholders, and consultations with the Mali Ministry of Health. As a result of advocacy, mental health was a key component of Mali's National Fistula Prevention and Treatment Strategy (2018-2022). CONCLUSION: The high prevalence of depression in Malian fistula patients underscores a need for more robust mental health support for patients after surgery. Data on mental health from routine screening informs community reintegration strategies for individual patients, elevates the overall quality of care of fistula repair programs by addressing patients' holistic health needs, and contributes to evidence-informed decision-making and data-driven policy change within the larger health system.

Cell numbers, distribution, shape, and regional variation throughout the murine hippocampal formation from the adult brain Allen Reference Atlas.

Quantifying the distribution of cells in every brain region is fundamental to attaining a comprehensive census of distinct neuronal and glial types. Until recently, estimating neuron numbers involved time-consuming procedures that were practically limited to stereological sampling. Progress in open-source image recognition software, growth in computing power, and unprecedented neuroinformatics developments now offer the potentially paradigm-shifting alternative of comprehensive cell-by-cell analysis in an entire brain region. The Allen Brain Atlas provides free digital access to complete series of raw Nissl-stained histological section images along with regional delineations. Automated cell segmentation of these data enables reliable and reproducible high-throughput quantification of regional variations in cell count, density, size, and shape at whole-system scale. While this strategy is directly applicable to any regions of the mouse brain, we first deploy it here on the closed-loop circuit of the hippocampal formation: the medial and lateral entorhinal cortices; dentate gyrus (DG); areas Cornu Ammonis 3 (CA3), CA2, and CA1; and dorsal and ventral subiculum. Using two independent image processing pipelines and the adult mouse reference atlas, we report the first cellular-level soma segmentation in every sub-region and non-principal layer of the left hippocampal formation through the full rostral-caudal extent. It is important to note that our techniques excluded the layers with the largest number of cells, DG granular and CA pyramidal, due to dense packing. The numerical estimates for the remaining layers are corroborated by traditional stereological sampling on a data subset and well match sparse published reports.

A Review of Studies Evaluating Insecticide Barrier Treatments for Mosquito Control From 1944 to 2018.

BACKGROUND AND PURPOSE: Barrier insecticide treatments have a long history in mosquito control programs but have been used more frequently in the United States in recent years for control of invasive "backyard" species (eg, Aedes albopictus) and increases in incidence of vector-borne diseases (eg, Zika). METHODS: We reviewed the published literature for studies investigating barrier treatments for mosquito control during the last 74 years (1944-2018). We searched databases such as PubMed, Web of Science, and Google Scholar to retrieve worldwide literature on barrier treatments. RESULTS: Forty-four studies that evaluated 20 active ingredients (AIs) and 21 formulated products against multiple mosquito species are included. Insecticides investigated for efficacy included organochlorines (dichlorodiphenyltrichloroethane [DDT], ß-hexachlorocyclohexane [BHC]), organophosphates (malathion), and pyrethroids (bifenthrin, deltamethrin, permethrin, lambda-cyhalothrin) as AIs. Study design varied with multiple methods used to evaluate effectiveness of barrier treatments. Barrier treatments were effective at lowering mosquito populations although there was variation between studies and for different mosquito species. Factors other than AI, such as exposure to rainfall and application equipment used, also influenced control efficacy. CONCLUSIONS: Many of the basic questions on the effectiveness of barrier insecticide applications have been answered, but several important details still must be investigated to improve precision and impact on vector-borne pathogen transmission. Recommendations are made to assist future evaluations of barrier treatments for mosquito control and to limit the potential development of insecticide resistance.

Estrogen regulates Bcl-w and Bim expression: role in protection against beta-amyloid peptide-induced neuronal death.

Estrogen is neuroprotective against a variety of insults, including beta-amyloid peptide (Abeta); however, the underlying mechanism(s) is not fully understood. Here, we report that 17beta-estradiol (E2) selectively regulates neuronal expression of the Bcl-2 family (bcl-2, bcl-x, bcl-w, bax, bak, bad, bik, bnip3, bid, and bim). In primary cerebrocortical neuron cultures under basal conditions, we observe that E2 upregulates expression of antiapoptotic Bcl-w and downregulates expression of proapoptotic Bim in an estrogen receptor (ER)-dependent manner. In the presence of toxic levels of Abeta, we observe that E2 attenuates indices of neuronal apoptosis: c-Jun N-terminal kinase (JNK)-dependent downregulation of Bcl-w and upregulation of Bim, mitochondrial release of cytochrome c and Smac, and cell death. These neuroprotective effects of E2 against Abeta-induced apoptosis are mimicked by the JNK inhibitor SP600125 (anthra[1,9-cd]pyrazol-6(2H)-one). In addition, E2 attenuates Abeta-induced JNK phosphorylation in an ER-dependent manner, but does not affect basal levels of JNK phosphorylation. These results suggest that E2 may reduce Abeta-induced neuronal apoptosis at least in part by two complementary pathways: (1) ER-dependent, JNK-independent upregulation of Bcl-w and downregulation of Bim under basal conditions, and (2) ER-dependent inhibition of Abeta-induced JNK activation and subsequent JNK-dependent downregulation of Bcl-w and upregulation of Bim, resulting in mitochondrial release of cytochrome c and Smac and eventual cell death. These data provide new understanding into the mechanisms contributing to estrogen neuroprotection, a neural function with potential therapeutic relevance to Alzheimer's disease.

Androgens regulate neprilysin expression: role in reducing beta-amyloid levels.

Age-related testosterone depletion in men is a risk factor for Alzheimer's disease. Prior studies suggest that androgens affect Alzheimer's disease risk by regulating accumulation of beta-amyloid protein (Abeta) by an undefined mechanism. In this study, we investigated the role of the Abeta-catabolizing enzyme neprilysin (NEP) in this process. First, we observed that androgens positively regulate neural expression of NEP in adult male rats. Next, we investigated androgen regulatory effects on both NEP expression and Abeta levels using cultured hippocampal neurons and neuronally differentiated rat pheochromocytoma cell 12 with or without androgen receptor (AR). Dihydrotestosterone (DHT) induced a time-dependent increase in NEP expression. DHT also significantly decreased levels of Abeta in AR-expressing cells transfected with amyloid precursor protein, but did not affect levels of either full-length or non-amyloidogenic, soluble amyloid precursor protein. Importantly, the DHT induced decrease of Abeta was blocked by pharmacological inhibition of NEP. The DHT-mediated increase in NEP expression and decrease in Abeta levels were (i) not observed in rat pheochromocytoma cell 12 lacking AR and (ii) blocked in AR-expressing cells by the antagonists, cyproterone acetate and flutamide. Together, these findings suggest that androgen regulation of Abeta involves an AR-dependent mechanism requiring up-regulation of the Abeta catabolizing enzyme NEP.

Signal transduction in Alzheimer disease: p21-activated kinase signaling requires C-terminal cleavage of APP at Asp664.

The deficits in Alzheimer disease (AD) stem at least partly from neurotoxic beta-amyloid peptides generated from the amyloid precursor protein (APP). APP may also be cleaved intracellularly at Asp664 to yield a second neurotoxic peptide, C31. Previously, we showed that cleavage of APP at the C-terminus is required for the impairments seen in APP transgenic mice, by comparing elements of the disease in animals modeling AD, with (platelet-derived growth factor B-chain promoter-driven APP transgenic mice; PDAPP) versus without (PDAPP D664A) a functional Asp664 caspase cleavage site. However, the signaling mechanism(s) by which Asp664 contributes to these deficits remains to be elucidated. In this study, we identify a kinase protein, recently shown to bind APP at the C-terminus and to contribute to AD, whose activity is modified in PDAPP mice, but normalized in PDAPP D664A mice. Specifically, we observed a significant increase in nuclear p21-activated kinase (isoforms 1, 2, and or 3; PAK-1/2/3) activation in hippocampus of 3 month old PDAPP mice compared with non-transgenic littermates, an effect completely prevented in PDAPP D664A mice. In contrast, 13 month old PDAPP mice displayed a significant decrease in PAK-1/2/3 activity, which was once again absent in PDAPP D664A mice. Similarly, in hippocampus of early and severe AD subjects, there was a progressive and subcellular-specific reduction in active PAK-1/2/3 compared with normal controls. Interestingly, total PAK-1/2/3 protein was increased in early AD subjects, but declined in moderate AD and declined further, to significantly below that of control levels, in severe AD. These findings are compatible with previous suggestions that PAK may be involved in the pathophysiology of AD, and demonstrate that both early activation and late inactivation in the murine AD model require the cleavage of APP at Asp664.