Bace1 Deletion in the Adult Reverses Epileptiform Activity and Sleep-wake Disturbances in AD Mice.

Alzheimer's disease (AD) increases the risk for seizures and sleep disorders. We show here that germline deletion of ß-site amyloid precursor protein (APP) cleaving enzyme-1 (BACE1) in neurons, but not in astrocytes, increased epileptiform activity. However, Bace1 deletion at adult ages did not alter the normal EEG waveform, indicating less concern for BACE1 inhibition in patients. Moreover, we showed that deletion of Bace1 in the adult was able to reverse epileptiform activity in 5xFAD mice. Intriguingly, treating 5xFAD and APPNL-G-F/NL-G-F (APP KI) mice of either sex with one BACE1 inhibitor Lanabecestat (AZD3293) dramatically increased epileptiform spiking, likely resulting from an off-target effect. We also monitored sleep-wake pathologies in these mice and showed increased wakefulness, decreased non-rapid eye movement sleep, and rapid eye movement sleep in both 5xFAD and APP KI mice; BACE1 inhibition in the adult 5xFAD mice reversed plaque load and sleep disturbances, but this was not seen in APP KI mice. Further studies with and without BACE1 inhibitor treatment showed different levels of plaque-associated microgliosis and activated microglial proteins in 5xFAD mice compared with APP KI mice. Together, BACE1 inhibition should be developed to avoid off-target effect for achieving benefits in reducing epileptic activity and sleep disturbance in Alzheimer's patients.SIGNIFICANCE STATEMENT BACE1 is widely recognized as a therapeutic target for treating Alzheimer's disease patients. However, BACE1 inhibitors failed in clinical trials because of inability to show cognitive improvement in patients. Here we show that BACE1 inhibition actually reduces sleep disturbances and epileptic seizures; both are seen in AD patients. We further showed that one of clinically tested BACE1 inhibitors does have off-target effects, and development of safer BACE1 inhibitors will be beneficial to AD patients. Results from this study will provide useful guidance for additional drug development.

Patient-reported outcome measure use among older adults after emergency department care: A systematic review.

BACKGROUND: Patient-reported outcome measures (PROMs) are gaining favor in clinical and research settings given their ability to capture a patient's symptom burden, functional status, and quality of life. Our objective in this systematic review was to summarize studies including PROMs assessed among older adults (age ≥ 65 years) after seeking emergency care. METHODS: With the assistance of a medical librarian, we searched Ovid MEDLINE, PubMed, Embase, CINAHL, Web of Science-Core Collection, and Cochrane CENTRAL from inception through June 2023 for studies in which older adult ED patients had PROMs assessed in the post-emergency care time period. Independent reviewers performed title/abstract review, full-text screening, data extraction, study characteristic summarization, and risk-of-bias (RoB) assessments. RESULTS: Our search strategy yielded 5153 studies of which 56 met study inclusion criteria. Within included studies, 304 unique PROM assessments were performed at varying time points after the ED visit, including 61 unique PROMs. The most commonly measured domain was physical function, assessed within the majority of studies (47/56; 84%), with measures including PROMs such as Katz activities of daily living (ADLs), instrumental ADLs, and the Barthel Index. PROMs were most frequently assessed at 1-3 months after an ED visit (113/304; 37%), greater than 6 months (91/304; 30%), and 4-6 months (88/304; 29%), with very few PROMs assessed within 1 month of the ED visit (12/304; 4%). Of the 16 interventional studies, two were determined to have a low RoB, four had moderate RoB, nine had high RoB, and one had insufficient information. Of the 40 observational studies, 10 were determined to be of good quality, 20 of moderate quality, and 10 of poor quality. CONCLUSIONS: PROM assessments among older adults following an ED visit frequently measured physical function, with very few assessments occurring within the first 1 month after an ED visit.

BACE1 regulates expression of Clusterin in astrocytes for enhancing clearance of ß-amyloid peptides.

BACKGROUND: Abnormal accumulation of amyloid beta peptide (Aß) in the brain induces a cascade of pathological changes in Alzheimer's disease (AD), and inhibiting BACE1, which is required for Aß generation, is therefore being explored for the treatment of AD by reducing Aß accumulation. As Bace1 knockout mice exhibit increased number of reactive astrocytes and AD brains have reactive astrocytes that surround amyloid plaques, we investigated the role of BACE1 in astrocytes and determined whether BACE1 regulates astrocytic functions. METHODS: We conducted unbiased single cell RNA-seq (scRNA-seq) using purified astrocytes from Bace1 KO mice and wild type control littermates. Similar scRNA-seq was also conducted using AD mice with conditional deletion of Bace1 in the adult stage (5xFAD;Bace1fl/fl;UBC-creER compared to 5xFAD;Bace1fl/fl controls). We compared the transcriptomes of astrocyte and reactive astrocyte clusters and identified several differentially expressed genes, which were further validated using Bace1 KO astrocyte cultures. Mice with astrocyte-specific Bace1 knockout in 5xFAD background were used to compare amyloid deposition. Mechanistic studies using cultured astrocytes were used to identify BACE1 substrates for changes in gene expression and signaling activity. RESULTS: Among altered genes, Clusterin (Clu) and Cxcl14 were significantly upregulated and validated by measuring protein levels. Moreover, BACE1 deficiency enhanced both astrocytic Aß uptake and degradation, and this effect was significantly attenuated by siRNA knockdown of Clu. Mechanistic study suggests that BACE1 deficiency abolishes cleavage of astrocytic insulin receptors (IR), and this may enhance expression of Clu and Cxcl14. Acutely isolated astrocytes from astrocyte-specific knockout of Bace1 mice (Bace1 fl/fl;Gfap-cre) show similar increases in CLU and IR. Furthermore, astrocyte-specific knockout of Bace1 in a 5xFAD background resulted in a significant attenuation in cortical Aß plaque load through enhanced clearance. CONCLUSION: Together, our study suggests that BACE1 in astrocytes regulates expression of Clu and Cxcl14, likely via the control of insulin receptor pathway, and inhibition of astrocytic BACE1 is a potential alternative strategy for enhancing Aß clearance.

Recruitment into Academic Neurosurgery Using a Model for Successful Cross-Campus Research Collaboration: A Premedical Student Survey.

OBJECTIVE: Recruitment of diverse and talented students to the field of neurosurgery is key to its continued growth and scientific advancement. Barriers, including poor perceptions and lack of early exposure, can impact recruitment and have been compounded by the ongoing COVID-19 pandemic. This study examines the impact of an inaugural Neurosurgery Research Consortium meeting on premedical students, assessing whether this exposure generated interest and improved perceptions of a career in neurosurgery. METHODS: Premedical students were recruited to virtually attend an inaugural Neurosurgery Research Consortium developed by the affiliated medical school's American Association of Neurological Surgeons (AANS) Student Chapter. Questionnaires were distributed to students before and after the meeting to assess student demographics and perceptions of neurosurgery. RESULTS: A total of 54 students attended the meeting, with general interest in neurosurgery, medicine, and research opportunities being the primary factors for attendance. Following the research meeting, we found that students perceived neurosurgeons to be friendlier and more approachable, with a more positive quality of life (QoL). Overall perceptions of neurosurgery improved after the meeting, but perceptions among racial and ethnic minority students did not significantly change in the areas of diversity, inclusion, and equity. CONCLUSIONS: These results suggest recruitment strategies targeting undergraduate students may improve their perception of neurosurgery as a career, and may mitigate some barriers to entry. These strategies are cost effective and easily replicable, making an easily implementable approach to provide direct insight into neurosurgery for future medical students while also promoting academic efforts in the field of neurosurgery.