Fenfluramine increases survival and reduces markers of neurodegeneration in a mouse model of Dravet syndrome

OBJECTIVE

In patients with Dravet syndrome (DS), fenfluramine reduced convulsive seizure frequency and provided clinical benefit in nonseizure endpoints (e.g., executive function, survival). In zebrafish mutant scn1 DS models, chronic fenfluramine treatment preserved neuronal cytoarchitecture prior to seizure onset and prevented gliosis; here, we extend these findings to a mammalian model of DS (Scn1a+/- mice) by evaluating the effects of fenfluramine on neuroinflammation (degenerated myelin, activated microglia) and survival.

METHODS

Scn1a+/- DS mice were treated subcutaneously once daily with fenfluramine (15 mg/kg) or vehicle from postnatal day (PND) 7 until 35-37. Sagittal brain sections were processed for immunohistochemistry using antibodies to degraded myelin basic protein (D-MBP) for degenerated myelin, or CD11b for activated (inflammatory) microglia; sections were scored semi-quantitatively. Apoptotic nuclei were quantified by TUNEL assay. Statistical significance was evaluated by 1-way ANOVA with post-hoc Dunnett's test (D-MBP, CD11b, and TUNEL) or Logrank Mantel-Cox (survival).

RESULTS

Quantitation of D-MBP immunostaining per 0.1 mm2 unit area of the parietal cortex and hippocampus CA3 yielded significantly higher spheroidal and punctate myelin debris counts in vehicle-treated DS mice than in wild-type mice. Fenfluramine treatment in DS mice significantly reduced these counts. Activated CD11b + microglia were more abundant in DS mouse corpus callosum and hippocampus than in wild-type controls. Fenfluramine treatment of DS mice resulted in significantly fewer activated CD11b + microglia than vehicle-treated DS mice in these brain regions. TUNEL staining in corpus callosum was increased in DS mice relative to wild-type controls. Fenfluramine treatment in DS mice lowered TUNEL staining relative to vehicle-treated DS mice. By PND 35-37, 55% of control DS mice had died, compared with 24% of DS mice receiving fenfluramine treatment (P = 0.0291).

SIGNIFICANCE

This is the first report of anti-neuroinflammation and pro-survival after fenfluramine treatment in a mammalian DS model. These results corroborate prior data in humans and animal models and suggest important pharmacological activities for fenfluramine beyond seizure reduction.

PLAIN LANGUAGE SUMMARY

Dravet syndrome is a severe epilepsy disorder that impairs learning and causes premature death. Clinical studies in patients with Dravet syndrome show that fenfluramine reduces convulsive seizures. Additional studies suggest that fenfluramine may have benefits beyond seizures, including promoting survival and improving control over emotions and behavior. Our study is the first to use a Dravet mouse model to investigate nonseizure outcomes of fenfluramine. Results showed that fenfluramine treatment of Dravet mice reduced neuroinflammation significantly more than saline treatment. Fenfluramine-treated Dravet mice also lived longer than saline-treated mice. These results support clinical observations that fenfluramine may have benefits beyond seizures.

Lipid-induced polymorphic amyloid fibril formation by α-synuclein

Many proteins that self-assemble into amyloid and amyloid-like fibers can adopt diverse polymorphic forms. These forms have been observed both in vitro and in vivo and can arise through variations in the steric-zipper interactions between β-sheets, variations in the arrangements between protofilaments, and differences in the number of protofilaments that make up a given fiber class. Different polymorphs arising from the same precursor molecule not only exhibit different levels of toxicity, but importantly can contribute to different disease conditions. However, the factors which contribute to formation of polymorphic forms of amyloid fibrils are not known. In this work, we show that in the presence of 1,2-dimyristoyl-sn-glycero-3-phospho-L-serine, a highly abundant lipid in the plasma membrane of neurons, the aggregation of α-synuclein is markedly accelerated and yields a diversity of polymorphic forms under identical experimental conditions. This morphological diversity includes thin and curly fibrils, helical ribbons, twisted ribbons, nanotubes, and flat sheets. Furthermore, the amyloid fibrils formed incorporate lipids into their structures, which corroborates the previous report of the presence of α-synuclein fibrils with high lipid content in Lewy bodies. Thus, the present study demonstrates that an interface, such as that provided by a lipid membrane, can not only modulate the kinetics of α-synuclein amyloid aggregation but also plays an important role in the formation of morphological variants by incorporating lipid molecules in the process of amyloid fibril formation.

Estimating the Incidence and Key Risk Factors of Cardiovascular Disease in Patients at High Risk of Imminent Fracture Using Routinely Collected Real-World Data From the UK

The objective of this work was to estimate the incidence rate of cardiovascular disease (CVD) events (myocardial infarction, stroke, or CVD death) at 1 year among three cohorts of patients at high risk of fracture (osteoporosis, previous fracture, and anti-osteoporosis medication) and to identify the key risk factors of CVD events in these three cohorts. To do so, this prospective cohort study used data from the Clinical Practice Research Datalink, a primary care database from United Kingdom. Major adverse cardiovascular events (MACE, a composite outcome for the occurrence of either myocardial infarction [MI], stroke, or CVD death) were identified in patients aged 50 years or older at high or imminent fracture risk identified in three different cohorts (not mutually exclusive): recently diagnosed with osteoporosis (OST, n = 65,295), incident fragility fracture (IFX, n = 67,065), and starting oral bisphosphonates (OBP, n = 145,959). About 1.90%, 4.39%, and 2.38% of the participants in OST, IFX, and OBP cohorts, respectively, experienced MACE events. IFX was the cohort with the higher risk: MACE incidence rates (cases/1000 person-years) were 19.63 (18.54-20.73) in OST, 52.64 (50.7-54.5) in IFX, and 26.26 (25.41-27.12) in OBP cohorts. Risk of MACE events at 1 year was predicted in the three cohorts. Models using a set of general, CVD, and fracture candidates selected by lasso regression had a good discrimination (≥70%) and internal validity and generally outperformed the models using only the CVD risk factors of general population listed in QRISK tool. Main risk factors common in all MACE models were sex, age, smoking, alcohol, atrial fibrillation, antihypertensive medication, prior MI/stroke, established CVD, glomerular filtration rate, systolic blood pressure, cholesterol levels, and number of concomitant medicines. Identified key risk factors highlight the differences of patients at high risk of fracture versus general population. Proposed models could improve prediction of CVD events in patients with osteoporosis in primary care settings. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Long-Term Impact of Single Epilepsy Training on Knowledge, Attitude and Practices: Comparison of Trained and Untrained Rwandan Community Health Workers

Objectives: To close the epilepsy treatment gap and reduce related stigma, eradication of misconceptions is importantIn 2014, Community Health Workers (CHWs) from Musanze (Northern Rwanda) were trained on different aspects of epilepsy. This study compared knowledge, attitude and practices (KAPs) towards epilepsy of trained CHWs 3 years after training, to untrained CHWs from Rwamagana (Eastern Rwanda). Methods: An epilepsy KAP questionnaire was administered to 96 trained and 103 untrained CHWs. Demographic and intergroup KAP differences were analysed by response frequencies. A multivariate analyses was performed based on desired and undesired response categories. Results: Epilepsy awareness was high in both groups, with better knowledge levels in trained CHWs. Negative attitudes were lowest in trained CHWs, yet 17% still reported misconceptions. Multivariate analysis demonstrated the impact of the training, irrespective of age, gender and educational level. Knowing someone with epilepsy significantly induced more desired attitudes. Conclusion: Despite demographic differences between trained and untrained CHWs, a single epilepsy training resulted in significant improvement of desired KAPs after 3 years. Nation-wide CHW training programs with focus on training-resistant items, e.g., attitudes, are recommended.