ABSTRACT
Alzheimer's disease (AD) is the leading cause of dementia in older adults, and the need for effective, sustainable therapeutic targets is imperative. The complement pathway has been proposed as a therapeutic target. C5aR1 inhibition reduces plaque load, gliosis, and memory deficits in animal models, however, the cellular bases underlying this neuroprotection were unclear. Here, we show that the C5aR1 antagonist PMX205 improves outcomes in the Arctic48 mouse model of AD. A combination of single cell and single nucleus RNA-seq analysis of hippocampi derived from males and females identified neurotoxic disease-associated microglia clusters in Arctic mice that are C5aR1-dependent, while microglial genes associated with synapse organization and transmission and learning were overrepresented in PMX205-treated mice. PMX205 also reduced neurotoxic astrocyte gene expression, but clusters associated with protective responses to injury were unchanged. C5aR1 inhibition promoted mRNA-predicted signaling pathways between brain cell types associated with cell growth and repair, while suppressing inflammatory pathways. Finally, although hippocampal plaque load was unaffected, PMX205 prevented deficits in short-term memory in female Arctic mice. In conclusion, C5aR1 inhibition prevents cognitive loss, limits detrimental glial polarization while permitting neuroprotective responses, as well as leaving most protective functions of complement intact, making C5aR1 antagonism an attractive therapeutic strategy for AD.
Subject(s)
Alzheimer Disease , Disease Models, Animal , Hippocampus , Microglia , Receptor, Anaphylatoxin C5a , Signal Transduction , Animals , Receptor, Anaphylatoxin C5a/antagonists & inhibitors , Receptor, Anaphylatoxin C5a/metabolism , Receptor, Anaphylatoxin C5a/genetics , Alzheimer Disease/metabolism , Alzheimer Disease/drug therapy , Alzheimer Disease/pathology , Alzheimer Disease/genetics , Mice , Female , Male , Signal Transduction/drug effects , Microglia/drug effects , Microglia/metabolism , Hippocampus/metabolism , Hippocampus/pathology , Hippocampus/drug effects , Neuroglia/drug effects , Neuroglia/metabolism , Astrocytes/drug effects , Astrocytes/metabolism , Mice, Transgenic , Humans , Mice, Inbred C57BLABSTRACT
Cranial radiation therapy (RT) for brain cancers leads to an irreversible decline in cognitive function without an available remedy. Radiation-induced cognitive deficits (RICD) are particularly a pressing problem for the survivors of pediatric and low grade glioma (LGG) patients who often live long post-RT. Radiation-induced elevated neuroinflammation and gliosis, triggered by the detrimental CNS complement cascade, lead to excessive synaptic and cognitive loss. Using intact and brain cancer-bearing mouse models, we now show that targeting anaphylatoxin complement C5a receptor (C5aR1) is neuroprotective against RICD. We used a genetic knockout, C5aR1 KO mouse, and a pharmacologic approach, employing the orally active, brain penetrant C5aR1 antagonist PMX205, to reverse RICD. Irradiated C5aR1 KO and WT mice receiving PMX205 showed significant neurocognitive improvements in object recognition memory and memory consolidation tasks. C5aR1 inhibition reduced microglial activation, astrogliosis, and synaptic loss in the irradiated brain. Importantly, C5aR1 inhibition in the syngeneic, orthotopic astrocytoma, and glioblastoma-bearing mice protected against RICD without interfering with the therapeutic efficacy of RT to reduce tumor volume in vivo . PMX205 is currently in clinical trials for amyotrophic lateral sclerosis (ALS). Thus, C5aR1 inhibition is a translationally feasible approach to address RICD, an unmet medical need.
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Background: Apolipoprotein E ε4 (APOE4) is the strongest genetic risk factor for late-onset Alzheimer's disease (LOAD). A recent case report identified a rare variant in APOE, APOE3-R136S (Christchurch), proposed to confer resistance to autosomal dominant Alzheimer's Disease (AD). However, it remains unclear whether and how this variant exerts its protective effects. Methods: We introduced the R136S variant into mouse Apoe (ApoeCh) and investigated its effect on the development of AD-related pathology using the 5xFAD model of amyloidosis and the PS19 model of tauopathy. We used immunohistochemical and biochemical analysis along with single-cell spatial transcriptomics and proteomics to explore the impact of the ApoeCh variant on AD pathological development and the brain's response to plaques and tau. Results: In 5xFAD mice, ApoeCh enhances a Disease-Associated Microglia (DAM) phenotype in microglia surrounding plaques, and reduces plaque load, dystrophic neurites, and plasma neurofilament light chain. By contrast, in PS19 mice, ApoeCh suppresses the microglial and astrocytic responses to tau-laden neurons and does not reduce tau accumulation or phosphorylation, but partially rescues tau-induced synaptic and myelin loss. We compared how microglia responses differ between the two mouse models to elucidate the distinct DAM signatures induced by ApoeCh. We identified upregulation of antigen presentation-related genes in the DAM response in a PS19 compared to a 5xFAD background, suggesting a differential response to amyloid versus tau pathology that is modulated by the presence of ApoeCh. Conclusions: These findings highlight the ability of the ApoeCh variant to modulate microglial responses based on the type of pathology, enhancing DAM reactivity in amyloid models and dampening neuroinflammation to promote protection in tau models. This suggests that the Christchurch variant's protective effects likely involve multiple mechanisms, including changes in receptor binding and microglial programming.
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INTRODUCTION: Emerging evidence links changes in the gut microbiome to late-onset Alzheimer's disease (LOAD), necessitating examination of AD mouse models with consideration of the microbiome. METHODS: We used shotgun metagenomics and untargeted metabolomics to study the human amyloid beta knock-in (hAß-KI) murine model for LOAD compared to both wild-type (WT) mice and a model for early-onset AD (3xTg-AD). RESULTS: Eighteen-month female (but not male) hAß-KI microbiomes were distinct from WT microbiomes, with AD genotype accounting for 18% of the variance by permutational multivariate analysis of variance (PERMANOVA). Metabolomic diversity differences were observed in females, however no individual metabolites were differentially abundant. hAß-KI mice microbiomes were distinguishable from 3xTg-AD animals (81% accuracy by random forest modeling), with separation primarily driven by Romboutsia ilealis and Turicibacter species. Microbiomes were highly cage specific, with cage assignment accounting for more than 40% of the PERMANOVA variance between the groups. DISCUSSION: These findings highlight a sex-dependent variation in the microbiomes of hAß-KI mice and underscore the importance of considering the microbiome when designing studies that use murine models for AD. HIGHLIGHTS: Microbial diversity and the abundance of several species differed in human amyloid beta knock-in (hAß-KI) females but not males. Correlations to Alzheimer's disease (AD) genotype were stronger for the microbiome than the metabolome. Microbiomes from hAß-KI mice were distinct from 3xTg-AD mice. Cage effects accounted for most of the variance in the microbiome and metabolome.
Subject(s)
Alzheimer Disease , Amyloid beta-Peptides , Disease Models, Animal , Genotype , Mice, Transgenic , Animals , Female , Humans , Male , Mice , Alzheimer Disease/microbiology , Alzheimer Disease/genetics , Amyloid beta-Peptides/metabolism , Gastrointestinal Microbiome , Gene Knock-In Techniques , Metabolomics , Microbiota , Sex CharacteristicsABSTRACT
INTRODUCTION: Alzheimer's disease (AD) is a neurodegenerative disorder with multifactorial etiology, including genetic factors that play a significant role in disease risk and resilience. However, the role of genetic diversity in preclinical AD studies has received limited attention. METHODS: We crossed five Collaborative Cross strains with 5xFAD C57BL/6J female mice to generate F1 mice with and without the 5xFAD transgene. Amyloid plaque pathology, microglial and astrocytic responses, neurofilament light chain levels, and gene expression were assessed at various ages. RESULTS: Genetic diversity significantly impacts AD-related pathology. Hybrid strains showed resistance to amyloid plaque formation and neuronal damage. Transcriptome diversity was maintained across ages and sexes, with observable strain-specific variations in AD-related phenotypes. Comparative gene expression analysis indicated correlations between mouse strains and human AD. DISCUSSION: Increasing genetic diversity promotes resilience to AD-related pathogenesis, relative to an inbred C57BL/6J background, reinforcing the importance of genetic diversity in uncovering resilience in the development of AD. HIGHLIGHTS: Genetic diversity's impact on AD in mice was explored. Diverse F1 mouse strains were used for AD study, via the Collaborative Cross. Strain-specific variations in AD pathology, glia, and transcription were found. Strains resilient to plaque formation and plasma neurofilament light chain (NfL) increases were identified. Correlations with human AD transcriptomics were observed.
Subject(s)
Alzheimer Disease , Resilience, Psychological , Mice , Humans , Female , Animals , Alzheimer Disease/pathology , Plaque, Amyloid/pathology , Mice, Inbred C57BL , Microglia/metabolism , Genetic Variation/genetics , Disease Models, Animal , Mice, Transgenic , Amyloid beta-Peptides/metabolismABSTRACT
INTRODUCTION: The BIN1 coding variant rs138047593 (K358R) is linked to Late-Onset Alzheimer's Disease (LOAD) via targeted exome sequencing. METHODS: To elucidate the functional consequences of this rare coding variant on brain amyloidosis and neuroinflammation, we generated BIN1K358R knock-in mice using CRISPR/Cas9 technology. These mice were subsequently bred with 5xFAD transgenic mice, which serve as a model for Alzheimer's pathology. RESULTS: The presence of the BIN1K358R variant leads to increased cerebral amyloid deposition, with a dampened response of astrocytes and oligodendrocytes, but not microglia, at both the cellular and transcriptional levels. This correlates with decreased neurofilament light chain in both plasma and brain tissue. Synaptic densities are significantly increased in both wild-type and 5xFAD backgrounds homozygous for the BIN1K358R variant. DISCUSSION: The BIN1 K358R variant modulates amyloid pathology in 5xFAD mice, attenuates the astrocytic and oligodendrocytic responses to amyloid plaques, decreases damage markers, and elevates synaptic densities. HIGHLIGHTS: BIN1 rs138047593 (K358R) coding variant is associated with increased risk of LOAD. BIN1 K358R variant increases amyloid plaque load in 12-month-old 5xFAD mice. BIN1 K358R variant dampens astrocytic and oligodendrocytic response to plaques. BIN1 K358R variant decreases neuronal damage in 5xFAD mice. BIN1 K358R upregulates synaptic densities and modulates synaptic transmission.
Subject(s)
Alzheimer Disease , Animals , Mice , Alzheimer Disease/genetics , Alzheimer Disease/pathology , Amyloid beta-Peptides , Disease Models, Animal , Mice, Transgenic , Neuroglia/pathology , Plaque, Amyloid/pathology , HumansABSTRACT
BACKGROUND: Variants in ABCA7, a member of the ABC transporter superfamily, have been associated with increased risk for developing late onset Alzheimer's disease (LOAD). METHODS: CRISPR-Cas9 was used to generate an Abca7V1613M variant in mice, modeling the homologous human ABCA7V1599M variant, and extensive characterization was performed. RESULTS: Abca7V1613M microglia show differential gene expression profiles upon lipopolysaccharide challenge and increased phagocytic capacity. Homozygous Abca7V1613M mice display elevated circulating cholesterol and altered brain lipid composition. When crossed with 5xFAD mice, homozygous Abca7V1613M mice display fewer Thioflavin S-positive plaques, decreased amyloid beta (Aß) peptides, and altered amyloid precursor protein processing and trafficking. They also exhibit reduced Aß-associated inflammation, gliosis, and neuronal damage. DISCUSSION: Overall, homozygosity for the Abca7V1613M variant influences phagocytosis, response to inflammation, lipid metabolism, Aß pathology, and neuronal damage in mice. This variant may confer a gain of function and offer a protective effect against Alzheimer's disease-related pathology. HIGHLIGHTS: ABCA7 recognized as a top 10 risk gene for developing Alzheimer's disease. Loss of function mutations result in increased risk for LOAD. V1613M variant reduces amyloid beta plaque burden in 5xFAD mice. V1613M variant modulates APP processing and trafficking in 5xFAD mice. V1613M variant reduces amyloid beta-associated damage in 5xFAD mice.
Subject(s)
ATP-Binding Cassette Transporters , Alzheimer Disease , Amyloid beta-Peptides , Mice, Transgenic , Plaque, Amyloid , Animals , Mice , ATP-Binding Cassette Transporters/genetics , ATP-Binding Cassette Transporters/metabolism , Plaque, Amyloid/pathology , Plaque, Amyloid/genetics , Plaque, Amyloid/metabolism , Amyloid beta-Peptides/metabolism , Alzheimer Disease/genetics , Alzheimer Disease/pathology , Alzheimer Disease/metabolism , Neurons/metabolism , Neurons/pathology , Disease Models, Animal , Humans , Brain/pathology , Brain/metabolism , Microglia/metabolism , Microglia/pathology , Phagocytosis/genetics , Amyloid beta-Protein Precursor/geneticsABSTRACT
INTRODUCTION: Synaptic loss is a hallmark of Alzheimer's disease (AD) that correlates with cognitive decline in AD patients. Complement-mediated synaptic pruning has been associated with this excessive loss of synapses in AD. Here, we investigated the effect of C5aR1 inhibition on microglial and astroglial synaptic pruning in two mouse models of AD. METHODS: A combination of super-resolution and confocal and tridimensional image reconstruction was used to assess the effect of genetic ablation or pharmacological inhibition of C5aR1 on the Arctic48 and Tg2576 models of AD. RESULTS: Genetic ablation or pharmacological inhibition of C5aR1 partially rescues excessive pre-synaptic pruning and synaptic loss in an age and region-dependent fashion in two mouse models of AD, which correlates with improved long-term potentiation (LTP). DISCUSSION: Reduction of excessive synaptic pruning is an additional beneficial outcome of the suppression of C5a-C5aR1 signaling, further supporting its potential as an effective targeted therapy to treat AD. HIGHLIGHTS: C5aR1 ablation restores long-term potentiation in the Arctic model of AD. C5aR1 ablation rescues region specific excessive pre-synaptic loss. C5aR1 antagonist, PMX205, rescues VGlut1 loss in the Tg2576 model of AD. C1q tagging is not sufficient to induce VGlut1 microglial ingestion. Astrocytes contribute to excessive pre-synaptic loss at late stages of the disease.
Subject(s)
Alzheimer Disease , Mice , Animals , Humans , Alzheimer Disease/genetics , Synapses , Long-Term Potentiation , Disease Models, AnimalABSTRACT
INTRODUCTION: Synaptic loss is a hallmark of Alzheimer's disease (AD) that correlates with cognitive decline in AD patients. Complement-mediated synaptic pruning has been associated with this excessive loss of synapses in AD. Here, we investigated the effect of C5aR1 inhibition on microglial and astroglial synaptic pruning in two mouse models of AD. METHODS: A combination of super-resolution and confocal and tridimensional image reconstruction was used to assess the effect of genetic ablation or pharmacological inhibition of C5aR1 on the Arctic48 and Tg2576 models of AD. RESULTS: Genetic ablation or pharmacological inhibition of C5aR1 rescues the excessive pre-synaptic pruning and synaptic loss in an age and region dependent fashion in two mouse models of AD, which correlates with improved long-term potentiation (LTP). DISCUSSION: Reduction of excessive synaptic pruning is an additional beneficial outcome of the suppression of C5a-C5aR1 signaling, further supporting its potential as an effective targeted therapy to treat AD.
ABSTRACT
The contribution of the gut microbiome to neuroinflammation, cognition, and Alzheimer's disease progression has been highlighted over the past few years. Additionally, inhibition of various components of the complement system has repeatedly been demonstrated to reduce neuroinflammation and improve cognitive performance in AD mouse models. Whether the deletion of these complement components is associated with distinct microbiome composition, which could impact neuroinflammation and cognitive performance in mouse models has not yet been examined. Here, we provide a comprehensive analysis of conditional and constitutive knockouts, pharmacological inhibitors, and various housing paradigms for the animal models and wild-type controls at various ages. We aimed to determine the impact of C1q or C5aR1 inhibition on the microbiome in the Arctic and Tg2576 mouse models of AD, which develop amyloid plaques at different ages and locations. Analysis of fecal samples from WT and Arctic mice following global deletion of C1q demonstrated significant alterations to the microbiomes of Arctic but not WT mice, with substantial differences in abundances of Erysipelotrichales, Clostridiales and Alistipes. While no differences in microbiome diversity were detected between cohoused wildtype and Arctic mice with or without the constitutive deletion of the downstream complement receptor, C5aR1, a difference was detected between the C5aR1 sufficient (WT and Arctic) and deficient (C5ar1KO and ArcticC5aR1KO) mice, when the mice were housed segregated by C5aR1 genotype. However, cohousing of C5aR1 sufficient and deficient wildtype and Arctic mice resulted in a convergence of the microbiomes and equalized abundances of each identified order and genus across all genotypes. Similarly, pharmacologic treatment with the C5aR1 antagonist, PMX205, beginning at the onset of beta-amyloid plaque deposition in the Arctic and Tg2576 mice, demonstrated no impact of C5aR1 inhibition on the microbiome. This study demonstrates the importance of C1q in microbiota homeostasis in neurodegenerative disease. In addition, while demonstrating that constitutive deletion of C5aR1 can significantly alter the composition of the fecal microbiome, these differences are not present when C5aR1-deficient mice are cohoused with C5aR1-sufficient animals with or without the AD phenotype and suggests limited if any contribution of the microbiome to the previously observed prevention of cognitive and neuronal loss in the C5aR1-deficient AD models.
Subject(s)
Alzheimer Disease , Gastrointestinal Microbiome , Neurodegenerative Diseases , Animals , Mice , Alzheimer Disease/genetics , Complement C1q/genetics , Disease Models, Animal , Neuroinflammatory Diseases , Receptors, Complement/geneticsABSTRACT
Alzheimer's disease (AD) is the leading cause of dementia in older adults, and the need for effective, sustainable therapeutic targets is imperative. Pharmacologic inhibition of C5aR1 reduces plaque load, gliosis and memory deficits in animal models. However, the cellular basis underlying this neuroprotection and which processes were the consequence of amyloid reduction vs alteration of the response to amyloid were unclear. In the Arctic model, the C5aR1 antagonist PMX205 did not reduce plaque load, but deficits in short-term memory in female mice were prevented. Hippocampal single cell and single nucleus RNA-seq clusters revealed C5aR1 dependent and independent gene expression and cell-cell communication. Microglial clusters containing neurotoxic disease-associated microglial genes were robustly upregulated in Arctic mice and drastically reduced with PMX205 treatment, while genes in microglia clusters that were overrepresented in the Arctic-PMX205 vs Arctic group were associated with synapse organization and transmission and learning. PMX205 treatment also reduced some A-1 astrocyte genes. In spite of changes in transcript levels, overall protein levels of some reactive glial markers were relatively unchanged by C5aR1 antagonism, as were clusters associated with protective responses to injury. C5aR1 inhibition promoted signaling pathways associated with cell growth and repair, such as TGFß and FGF, in Arctic mice, while suppressing inflammatory pathways including PROS, Pecam1, and EPHA. In conclusion, pharmacologic C5aR1 inhibition prevents cognitive loss, limits microglial polarization to a detrimental inflammatory state and permits neuroprotective responses, as well as leaving protective functions of complement intact, making C5aR1 antagonism an attractive therapeutic strategy for individuals with AD.
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San Francisco implemented one of the most intensive, comprehensive, multipronged COVID-19 pandemic responses in the United States using 4 core strategies: (1) aggressive mitigation measures to protect populations at risk for severe disease, (2) prioritization of resources in neighborhoods highly affected by COVID-19, (3) timely and adaptive data-driven policy making, and (4) leveraging of partnerships and public trust. We collected data to describe programmatic and population-level outcomes. The excess all-cause mortality rate in 2020 in San Francisco was half that seen in 2019 in California as a whole (8% vs 16%). In almost all age and race and ethnicity groups, excess mortality from COVID-19 was lower in San Francisco than in California overall, with markedly diminished excess mortality among people aged >65 years. The COVID-19 response in San Francisco highlights crucial lessons, particularly the importance of community responsiveness, joint planning, and collective action, to inform future pandemic response and advance health equity.
Subject(s)
COVID-19 , Pandemics , Humans , United States , San Francisco/epidemiology , Pandemics/prevention & control , COVID-19/epidemiology , Ethnicity , Residence CharacteristicsABSTRACT
Background: Anticipating an increased utilization of healthcare facilities during the COVID-19 surge, the San Francisco Department of Public Health developed a plan to deploy neighborhood-based Field Care Clinics (FCCs) that would decompress emergency departments by serving patients with low acuity complaints. These clinics would receive patients directly from the Emergency Medical Services (EMS) system. Transports were initiated by a paramedic-driven protocol, originally by EMS crews and later by the Centralized Ambulance Destination Determination (CADDiE) System. In this study, we evaluated the outcomes of EMS patients who were transported to the FCC, specifically as to whether they required subsequent transfer to the emergency department. Methods: We performed a retrospective study of all patients transported to the Bayview-Hunters Point (BHP) neighborhood FCC by EMS between April 11th, 2020, and December 16th, 2020. Descriptive statistics and Chi-Square Tests were used to analyze patient data. Results: In total, 35 patients (20 men, 15 women, average age of 50.9 years) were transported to the FCC. Of these, 16 were Black/African American, 7 were White, 3 were Asian, with 9 identifying as of other races and 9 of Hispanic ethnicity. Twenty-three of these transports resulted from a CADDiE recommendation. Approximately half (n=20) of calls originated within the BHP neighborhood. The most frequent patient complaint was "Pain." Of patients transported to the FCC, 23 were treated and discharged. The 12 remaining patients required hospital transfer, with 3 being discharged after receiving treatment in the emergency department and 9 requiring hospital admission, psychiatric, or sobering services. The likelihood of hospital transfer did not significantly vary by sex (p=0.41), 9-1-1 call origination relative to BHP neighborhood (p=0.92), or CADDiE recommendation (p=0.51). Conclusion: Three-fourths of patients who required subsequent hospital transfer were admitted or required specialized services, suggesting that the FCC was viable for managing low acuity conditions. However, the underutilization of the FCC by EMS as a transport destination and a high hospital transfer rate indicates training and protocol refinement opportunities. Despite the small cohort size, this study demonstrates that an FCC alternative care site can act as a viable source for urgent and emergency care during a pandemic.
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BACKGROUND: The TREM2 R47H variant is one of the strongest genetic risk factors for late-onset Alzheimer's Disease (AD). Unfortunately, many current Trem2 R47H mouse models are associated with cryptic mRNA splicing of the mutant allele that produces a confounding reduction in protein product. To overcome this issue, we developed the Trem2R47H NSS (Normal Splice Site) mouse model in which the Trem2 allele is expressed at a similar level to the wild-type Trem2 allele without evidence of cryptic splicing products. METHODS: Trem2R47H NSS mice were treated with the demyelinating agent cuprizone, or crossed with the 5xFAD mouse model of amyloidosis, to explore the impact of the TREM2 R47H variant on inflammatory responses to demyelination, plaque development, and the brain's response to plaques. RESULTS: Trem2R47H NSS mice display an appropriate inflammatory response to cuprizone challenge, and do not recapitulate the null allele in terms of impeded inflammatory responses to demyelination. Utilizing the 5xFAD mouse model, we report age- and disease-dependent changes in Trem2R47H NSS mice in response to development of AD-like pathology. At an early (4-month-old) disease stage, hemizygous 5xFAD/homozygous Trem2R47H NSS (5xFAD/Trem2R47H NSS) mice have reduced size and number of microglia that display impaired interaction with plaques compared to microglia in age-matched 5xFAD hemizygous controls. This is associated with a suppressed inflammatory response but increased dystrophic neurites and axonal damage as measured by plasma neurofilament light chain (NfL) level. Homozygosity for Trem2R47H NSS suppressed LTP deficits and loss of presynaptic puncta caused by the 5xFAD transgene array in 4-month-old mice. At a more advanced (12-month-old) disease stage 5xFAD/Trem2R47H NSS mice no longer display impaired plaque-microglia interaction or suppressed inflammatory gene expression, although NfL levels remain elevated, and a unique interferon-related gene expression signature is seen. Twelve-month old Trem2R47H NSS mice also display LTP deficits and postsynaptic loss. CONCLUSIONS: The Trem2R47H NSS mouse is a valuable model that can be used to investigate age-dependent effects of the AD-risk R47H mutation on TREM2 and microglial function including its effects on plaque development, microglial-plaque interaction, production of a unique interferon signature and associated tissue damage.
Subject(s)
Alzheimer Disease , Demyelinating Diseases , Mice , Animals , Alzheimer Disease/metabolism , Cuprizone/metabolism , RNA Splicing , Mutation , Plaque, Amyloid/pathology , Disease Models, Animal , Demyelinating Diseases/metabolism , Demyelinating Diseases/pathology , Microglia/metabolism , Brain/metabolism , Membrane Glycoproteins/genetics , Membrane Glycoproteins/metabolism , Receptors, Immunologic/genetics , Receptors, Immunologic/metabolismABSTRACT
The complement system is an ancient collection of proteolytic cascades with well-described roles in regulation of innate and adaptive immunity. With the convergence of a revolution in complement-directed clinical therapeutics, the discovery of specific complement-associated targetable pathways in the central nervous system, and the development of integrated multi-omic technologies that have all emerged over the last 15 years, precision therapeutic targeting in Alzheimer disease and other neurodegenerative diseases and processes appears to be within reach. As a sensor of tissue distress, the complement system protects the brain from microbial challenge as well as the accumulation of dead and/or damaged molecules and cells. Additional more recently discovered diverse functions of complement make it of paramount importance to design complement-directed neurotherapeutics such that the beneficial roles in neurodevelopment, adult neural plasticity, and neuroprotective functions of the complement system are retained.
Subject(s)
Neuroinflammatory Diseases , Neuroprotection , Humans , Animals , Brain , Complement System Proteins , Neuronal Plasticity/physiology , Microglia/physiologyABSTRACT
BACKGROUND: Frontline providers mostly outside specific emergency areas deliver emergency care around the world, yet often they do not receive dedicated training in managing emergency conditions. When designed for low-resource settings, emergency care training has been shown to improve provider skills, facilitate efficient use of available resources, and reduce death and disability by ensuring timely access to life-saving care. METHODS: The WHO/ICRC Basic Emergency Care (BEC) Course with follow up longitudinal mentorship for 6 months was implemented in rural Neno District Malawi from September 2019-April 2020. We completed a mixed-methods analysis of the course and mentorship included mentor and participant surveys and feedback, mentorship quantification, and participant examination results. Simple descriptive statistics and boxplot visuals were used to describe participant demographics and mentorship quantification with a Wilcoxon signed-rank test to evaluate pre- and post-test scores. Qualitative feedback from participants and mentors were inductively analyzed using Dedoose. RESULTS: The median difference of BEC course examination percentage score between participants before the BEC course and immediately following the course was 18.0 (95% CI 14.0-22.0; p<0.001). Examination scores from the one-year post-test was lower but sustained above the pre-course test score with a median difference of 11.9 (95% CI 4.0-16.0; p<0.009). There were 174 mentorship activities with results suggesting that a higher number of mentorship touches and hours of mentor-mentee interactions may assist in sustained knowledge test scores. Reported strengths included course delivery approach leading to improved knowledge with mentorship enhancing skills, learning and improved confidence. Suggestions for improvement included more contextualized training and increased mentorship. CONCLUSION: The BEC course and subsequent longitudinal mentorship were feasible and acceptable to participants and mentors in the Malawian low resource context. Follow-up longitudinal mentorship was feasible and acceptable and is likely important to cementing the course concepts for long-term retention of knowledge and skills.
Subject(s)
Emergency Medical Services , Mentors , Humans , Malawi , Feasibility StudiesABSTRACT
A key challenge in developing diagnosis and treatments for Alzheimer's disease (AD) is to detect abnormal network activity at as early a stage as possible. To date, behavioral and neurophysiological investigations in AD model mice have yet to conduct a longitudinal assessment of cellular pathology, memory deficits, and neurophysiological correlates of neuronal activity. We therefore examined the temporal relationships between pathology, neuronal activities and spatial representation of environments, as well as object location memory deficits across multiple stages of development in the 5xFAD mice model and compared these results to those observed in wild-type mice. We performed longitudinal in vivo calcium imaging with miniscope on hippocampal CA1 neurons in behaving mice. We find that 5xFAD mice show amyloid plaque accumulation, depressed neuronal calcium activity during immobile states, and degenerate and unreliable hippocampal neuron spatial tuning to environmental location at early stages by 4 months of age while their object location memory (OLM) is comparable to WT mice. By 8 months of age, 5xFAD mice show deficits of OLM, which are accompanied by progressive degradation of spatial encoding and, eventually, impaired CA1 neural tuning to object-location pairings. Furthermore, depressed neuronal activity and unreliable spatial encoding at early stage are correlated with impaired performance in OLM at 8-month-old. Our results indicate the close connection between impaired hippocampal tuning to object-location and the presence of OLM deficits. The results also highlight that depressed baseline firing rates in hippocampal neurons during immobile states and unreliable spatial representation precede object memory deficits and predict memory deficits at older age, suggesting potential early opportunities for AD detecting.
Subject(s)
Alzheimer Disease , Mice , Animals , Alzheimer Disease/metabolism , Calcium/metabolism , Mice, Transgenic , Neurons/metabolism , Memory Disorders/etiology , Memory Disorders/metabolism , Hippocampus/metabolism , Disease Models, AnimalABSTRACT
Multiple studies have recognized the involvement of the complement cascade during Alzheimer's disease pathogenesis. However, the specific role of C5a-C5aR1 signaling in the progression of this neurodegenerative disease is still not clear. Furthermore, its potential as a therapeutic target to treat AD still remains to be elucidated. Canonically, generation of the anaphylatoxin C5a as the result of complement activation and interaction with its receptor C5aR1 triggers a potent inflammatory response. Previously, genetic ablation of C5aR1 in a mouse model of Alzheimer's disease exerted a protective effect by preventing cognitive deficits. Here, using PMX205, a potent, specific C5aR1 antagonist, in the Tg2576 mouse model of Alzheimer's disease we show a striking reduction in dystrophic neurites in parallel with the reduced amyloid load, rescue of the excessive pre-synaptic loss associated with AD cognitive impairment and the polarization of microglial gene expression towards a DAM-like phenotype that are consistent with the neuroprotective effects seen. These data support the beneficial effect of a pharmacological inhibition of C5aR1 as a promising therapeutic approach to treat Alzheimer's disease. Supportive of the safety of this treatment is the recent FDA-approval of another other C5a receptor 1 antagonist, Avacopan, as a treatment for autoimmune inflammatory diseases.
Subject(s)
Alzheimer Disease , Neurodegenerative Diseases , Alzheimer Disease/pathology , Animals , Disease Models, Animal , Disease Progression , Mice , Microglia/pathology , Neurodegenerative Diseases/metabolism , Receptor, Anaphylatoxin C5a/genetics , Receptor, Anaphylatoxin C5a/metabolismABSTRACT
BACKGROUND: The complement system is part of the innate immune system that clears pathogens and cellular debris. In the healthy brain, complement influences neurodevelopment and neurogenesis, synaptic pruning, clearance of neuronal blebs, recruitment of phagocytes, and protects from pathogens. However, excessive downstream complement activation that leads to generation of C5a, and C5a engagement with its receptor C5aR1, instigates a feed-forward loop of inflammation, injury, and neuronal death, making C5aR1 a potential therapeutic target for neuroinflammatory disorders. C5aR1 ablation in the Arctic (Arc) model of Alzheimer's disease protects against cognitive decline and neuronal injury without altering amyloid plaque accumulation. METHODS: To elucidate the effects of C5a-C5aR1 signaling on AD pathology, we crossed Arc mice with a C5a-overexpressing mouse (ArcC5a+) and tested hippocampal memory. RNA-seq was performed on hippocampus and cortex from Arc, ArcC5aR1KO, and ArcC5a+ mice at 2.7-10 months and age-matched controls to assess mechanisms involved in each system. Immunohistochemistry was used to probe for protein markers of microglia and astrocytes activation states. RESULTS: ArcC5a+ mice had accelerated cognitive decline compared to Arc. Deletion of C5ar1 delayed or prevented the expression of some, but not all, AD-associated genes in the hippocampus and a subset of pan-reactive and A1 reactive astrocyte genes, indicating a separation between genes induced by amyloid plaques alone and those influenced by C5a-C5aR1 signaling. Biological processes associated with AD and AD mouse models, including inflammatory signaling, microglial cell activation, and astrocyte migration, were delayed in the ArcC5aR1KO hippocampus. Interestingly, C5a overexpression also delayed the increase of some AD-, complement-, and astrocyte-associated genes, suggesting the possible involvement of neuroprotective C5aR2. However, these pathways were enhanced in older ArcC5a+ mice compared to Arc. Immunohistochemistry confirmed that C5a-C5aR1 modulation in Arc mice delayed the increase in CD11c-positive microglia, while not affecting other pan-reactive microglial or astrocyte markers. CONCLUSION: C5a-C5aR1 signaling in AD largely exerts its effects by enhancing microglial activation pathways that accelerate disease progression. While C5a may have neuroprotective effects via C5aR2, engagement of C5a with C5aR1 is detrimental in AD models. These data support specific pharmacological inhibition of C5aR1 as a potential therapeutic strategy to treat AD.
Subject(s)
Alzheimer Disease , Biological Phenomena , Alzheimer Disease/genetics , Alzheimer Disease/metabolism , Animals , Mice , Microglia/metabolism , Plaque, Amyloid/metabolism , Receptor, Anaphylatoxin C5a/genetics , Receptor, Anaphylatoxin C5a/metabolism , Signal TransductionABSTRACT
OBJECTIVES: The WHO developed a 5-day basic emergency care (BEC) course using the traditional lecture format. However, adult learning theory suggests that lecture-based courses alone may not promote long-term knowledge retention. We assessed whether a mobile application adjunct (BEC app) can have positive impact on knowledge acquisition and retention compared with the BEC course alone and evaluated perceptions, acceptability and barriers to adoption of such a tool. DESIGN: Mixed-methods prospective cohort study. PARTICIPANTS: Adult healthcare workers in six health facilities in Tanzania who enrolled in the BEC course and were divided into the control arm (BEC course) or the intervention arm (BEC course plus BEC app). MAIN OUTCOME MEASURES: Changes in knowledge assessment scores, self-efficacy and perceptions of BEC app. RESULTS: 92 enrolees, 46 (50%) in each arm, completed the BEC course. 71 (77%) returned for the 4-month follow-up. Mean test scores were not different between the two arms at any time period. Both arms had significantly improved test scores from enrolment (prior to distribution of materials) to day 1 of the BEC course and from day 1 of BEC course to immediately after BEC course completion. The drop-off in mean scores from immediately after BEC course completion to 4 months after course completion was not significant for either arm. No differences were observed between the two arms for any self-efficacy question at any time point. Focus groups revealed five major themes related to BEC app adoption: educational utility, clinical utility, user experience, barriers to access and barriers to use. CONCLUSION: The BEC app was well received, but no differences in knowledge retention and self-efficacy were observed between the two arms and only a very small number of participants reported using the app. Technologic-based, linguistic-based and content-based barriers likely limited its impact.