Shaping the future of preclinical development of successful disease-modifying drugs against Alzheimer's disease: a systematic review of tau propagation models

The transcellular propagation of the aberrantly modified protein tau along the functional brain network is a key hallmark of Alzheimer's disease and related tauopathies. Inoculation-based tau propagation models can recapitulate the stereotypical spread of tau and reproduce various types of tau inclusions linked to specific tauopathy, albeit with varying degrees of fidelity. With this systematic review, we underscore the significance of judicious selection and meticulous functional, biochemical, and biophysical characterization of various tau inocula. Furthermore, we highlight the necessity of choosing suitable animal models and inoculation sites, along with the critical need for validation of fibrillary pathology using confirmatory staining, to accurately recapitulate disease-specific inclusions. As a practical guide, we put forth a framework for establishing a benchmark of inoculation-based tau propagation models that holds promise for use in preclinical testing of disease-modifying drugs.

A survey in the West Midlands of the United Kingdom of current practice in managing hypotension in lower segment caesarean section under spinal anaesthesia

BACKGROUND

Spinal anaesthesia, the most common form of anaesthesia for caesarean section, leads to sympathetic blockade and profound maternal hypotension resulting in adverse maternal and neonatal outcomes. Hypotension, nausea and vomiting remain common but until the publication of the National Institute of Health and Care Excellence (NICE) 2021 guidance, no national guideline existed on how best to manage maternal hypotension following spinal anaesthesia for caesarean section. A 2017 international consensus statement recommended prophylactic vasopressor administration to maintain a systolic blood pressure of >90% of an accurate pre-spinal value, and to avoid a drop to <80% of this value. This survey aimed to assess regional adherence to these recommendations, the presence of local guidelines for management of hypotension during caesarean section under spinal anaesthesia, and the individual clinician's treatment thresholds for maternal hypotension and tachycardia.

METHODS

The West Midlands Trainee-led Research in Anaesthesia and Intensive Care Network co-ordinated surveys of obstetric anaesthetic departments and consultant obstetric anaesthetists across 11 National Health Service Trusts in the Midlands, England.

RESULTS

One-hundred-and-two consultant obstetric anaesthetists returned the survey and 73% of sites had a policy for vasopressor use; 91% used phenylephrine as the first-line drug but a wide range of recommended delivery methods was noted and target blood pressure was only listed in 50% of policies. Significant variation existed in both vasopressor delivery methods and target blood pressures.

CONCLUSIONS

Although NICE has since recommended prophylactic phenylephrine infusion and a target blood pressure, the previous international consensus statement was not adhered to routinely.

Does modulation of tau hyperphosphorylation represent a reasonable therapeutic strategy for Alzheimer's disease? From preclinical studies to the clinical trials

Protein kinases (PKs) have emerged as one of the most intensively investigated drug targets in current pharmacological research, with indications ranging from oncology to neurodegeneration. Tau protein hyperphosphorylation was the first pathological post-translational modification of tau protein described in Alzheimer's disease (AD), highlighting the role of PKs in neurodegeneration. The therapeutic potential of protein kinase inhibitors (PKIs)) and protein phosphatase 2 A (PP2A) activators in AD has recently been explored in several preclinical and clinical studies with variable outcomes. Where a number of preclinical studies demonstrate a visible reduction in the levels of phospho-tau in transgenic tauopathy models, no reduction in neurofibrillary lesions is observed. Amongst the few PKIs and PP2A activators that progressed to clinical trials, most failed on the efficacy front, with only a few still unconfirmed and potential positive trends. This suggests that robust preclinical and clinical data is needed to unequivocally evaluate their efficacy. To this end, we take a systematic look at the results of preclinical and clinical studies of PKIs and PP2A activators, and the evidence they provide regarding the utility of this approach to evaluate the potential of targeting tau hyperphosphorylation as a disease modifying therapy.

Evolution of the intracranial features of congenital cytomegalovirus on MRI

AIM

To describe the evolution of the intracranial features of congenital cytomegalovirus (cCMV) on magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Sixteen infants with polymerase chain reaction (PCR)-confirmed cCMV who had undergone at least two MRI examinations of the brain were identified. Two paediatric neuroradiologists reviewed the baseline studies retrospectively for intracranial features of cCMV, including white matter signal abnormalities, subependymal cysts, malformations of cortical development, and intracranial calcification. The subsequent MRI studies were then reviewed and directly compared to the baseline examinations.

RESULTS

White matter signal abnormalities were seen on all 16 baseline studies (100%); these persisted on all subsequent examinations but were patchier, more focal, and associated with an interval reduction in white matter volume. Subependymal cysts were present on 11 (69%) of the baseline scans; these almost universally regressed (in 10 of the 11 cases [91%]), with no new cysts appreciable on subsequent imaging. Malformations of cortical development, exclusively in the form of polymicrogyria, were seen in six (38%) patients and persisted, unchanged, on subsequent imaging. Intracranial calcification was seen in a minority of baseline studies (4 [25%]) and remained stable on subsequent scans.

CONCLUSION

Children with cCMV who present later in life without an established or suspected underlying pathology can pose a challenge to the assessing radiologist. The radiological sequelae of cCMV can be non-specific; in some cases, white matter signal abnormalities and focal loss of white matter volume may be the only intracranial features. It is therefore important that radiologists are aware of cCMV as a potential differential for these findings.

Enriched environment ameliorates propagation of tau pathology and improves cognition in rat model of tauopathy

Introduction

The typical symptoms of Alzheimer’s disease (AD) are cognitive impairment, disrupted spatial orientation, behavioral and psychiatric abnormalities, and later motor deficits. Neuropathologically, AD is characterized by deposits of pathological forms of endogenous proteins – amyloid-β, and neurofibrillary tau protein pathology. The latter closely correlates with brain atrophy and clinical impairment. Pharmacological therapies for these pathologies are largely absent, raising the question whether non-pharmacological interventions could be efficacious. Environmental factors can play a role in the manifestation of AD. It is unknown whether enriched environment (EE) can ameliorate the propagation of protein aggregates or their toxic components.

Methods

We injected insoluble tau extracts from human brains with AD (600 or 900 ng per animal) into hippocampi of SHR72 transgenic rats that express non-mutated truncated human tau 151-391/4R, but usually do not develop hippocampal tangles. The rats had either standard housing, or could access an EE 5×/week for 3 months. Behavioral analysis included the Morris Water Maze (MWM). Histological analysis was used to assess the propagation of tau pathology.

Results

Animals exposed to EE performed better in the MWM (spatial acquisition duration and total distance, probe test); unexposed animals improved over the course of acquisition trials, but their mean performance remained below that of the EE group. Enriched environment abrogated tau propagation and hippocampal tangle formation in the 600 ng group; in the 900 ng group, tangle formation was ∼10-fold of the 600 ng group, and unaffected by EE.

Conclusion

Even a small difference in the amount of injected human AD tau can cause a pronounced difference in the number of resulting tangles. EE leads to a noticeably better spatial navigation performance of tau-injected animals. Furthermore, EE seems to be able to slow down tau pathology progression, indicating the possible utility of similar interventions in early stages of AD where tangle loads are still low.

Monoclonal antibodies targeting two immunodominant epitopes on the Spike protein neutralize emerging SARS-CoV-2 variants of concern

BACKGROUND

The emergence of new SARS-CoV-2 variants of concern B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma) and B.1.617.2 (Delta) that harbor mutations in the viral S protein raised concern about activity of current vaccines and therapeutic antibodies. Independent studies have shown that mutant variants are partially or completely resistant against some of the therapeutic antibodies authorized for emergency use.

METHODS

We employed hybridoma technology, ELISA-based and cell-based S-ACE2 interaction assays combined with authentic virus neutralization assays to develop second-generation antibodies, which were specifically selected for their ability to neutralize the new variants of SARS-CoV-2.

FINDINGS

AX290 and AX677, two monoclonal antibodies with non-overlapping epitopes, exhibit subnanomolar or nanomolar affinities to the receptor binding domain of the viral Spike protein carrying amino acid substitutions N501Y, N439K, E484K, K417N, and a combination N501Y/E484K/K417N found in the circulating virus variants. The antibodies showed excellent neutralization of an authentic SARS-CoV-2 virus representing strains circulating in Europe in spring 2020 and also the variants of concern B.1.1.7 (Alpha), B.1.351 (Beta) and B.1.617.2 (Delta). In addition, AX677 is able to bind Omicron Spike protein just like the wild type Spike. The combination of the two antibodies prevented the appearance of escape mutations of the authentic SARS-CoV-2 virus. Prophylactic administration of AX290 and AX677, either individually or in combination, effectively reduced viral burden and inflammation in the lungs, and prevented disease in a mouse model of SARS-CoV-2 infection.

INTERPRETATION

The virus-neutralizing properties were fully reproduced in chimeric mouse-human versions of the antibodies, which may represent a promising tool for COVID-19 therapy.

FUNDING

The study was funded by AXON Neuroscience SE and AXON COVIDAX a.s.

Diagnostic analysis of baseline brain MRI features in infants with congenital cytomegalovirus infection: a simplified scoring system

AIM

To characterise the magnetic resonance imaging (MRI) features of infants with congenital cytomegalovirus (CMV) and categorise those into a simplified MRI scoring system.

MATERIALS AND METHODS

Three neuroradiologists reviewed the examinations of 71 infants retrospectively and scored for the presence of a white matter signal abnormality and structural lesion and each MRI was given a score of 0, 1, 2, or 3 for normal, structural abnormality alone, white matter abnormality alone, white matter abnormality plus structural lesion, respectively. Imaging features were outlines according to symptomatology. Chi-square and Spearman's rho were used to test relationships between MRI features and viral loads and MRI score/symptomatic disease respectively. Cohen's Kappa coefficient was used to assess interobserver agreement.

RESULTS

Of the 49 abnormal studies, 40% (n=20) were seen in asymptomatic infants. The commonest finding was white matter signal abnormality, followed by cyst formation and polymicrogyria (86%, n=42; 71%, n=35; and 33%, n=16, respectively). Cysts were significantly positively correlated with white matter abnormalities and polymicrogyria. On the MRI score, 31%, 10%, 15%, and 44% obtained a score of 0, 1, 2, and 3, respectively; the MRI score was positively correlated with log-transformed viral loads. Interobserver agreement for the presence of white matter signal abnormality, cyst formation, malformations of cortical development (MCD), and global MRI score was excellent (k = 0.82, 0.94, 0.96, and 0.86, respectively).

CONCLUSION

Baseline MRI provides information valuable for treatment decisions, especially in "asymptomatic" infants. The simplified scoring system is easier to use, incorporating solely the imaging findings that are anticipated to have an effect on clinical outcome.

Polo-like Kinase 1 as an emerging drug target: structure, function and therapeutic implications

Polo-like kinase 1 (PLK1) is a conserved mitotic serine-threonine protein kinase, functions as a regulatory protein, and is involved in the progression of the mitotic cycle. It plays important roles in the regulation of cell division, maintenance of genome stability, in spindle assembly, mitosis, and DNA-damage response. PLK1 is consist of a N-terminal serine-threonine kinase domain, and a C-terminal Polo-box domain (regulatory site). The expression of PLK1 is controlled by transcription repressor in the G1 stage and transcription activators in the G2 stage of the cell cycle. Overexpression of PLK1 results in undermining of checkpoints causes excessive cellular division resulting in abnormal cell growth, leading to the development of cancer. Blocking the expression of PLK1 by an antibody, RNA interference, or kinase inhibitors, causes a subsequent reduction in the proliferation of tumour cells and induction of apoptosis in tumour cells without affecting the healthy cells, suggesting an attractive target for drug development. In this review, we discuss detailed information on expression, gene and protein structures, role in different diseases, and progress in the design and development of PLK1 inhibitors. We have performed an in-depth analysis of the PLK1 inhibitors and their therapeutic implications with special focus to the cancer therapeutics.

Anti-TNF therapy for paediatric IBD: the Scottish national experience

BACKGROUND AND AIMS

Biological agents are being increasingly used in the UK for paediatric-onset inflammatory bowel disease (PIBD) despite limited evidence and safety concerns. We evaluated effectiveness and safety in the clinical setting, highlighting drug cost pressures, using our national Scottish PIBD biological registry.

METHODS

Complete usage of the biological agents, infliximab (IFX) and adalimumab (ADA) for treatment of PIBD (in those aged <18 years) from 1 January 2000 to 30 September 2010 was collated from all treatments administered within the Scottish Paediatric Gastroenterology, Hepatology and Nutrition (PGHAN) national managed service network (all regional PGHAN centres and paediatric units within their associated district general hospitals).

RESULTS

132 children had biological therapy; 24 required both agents; 114 had Crohn's disease (CD), 16 had ulcerative colitis (UC) and 2 had IBD Unclassified (IBDU). 127 children received IFX to induce remission; 61 entered remission, 49 had partial response and 17 had no response. 72 were given maintenance IFX and 23 required dose escalation. 18 had infusion reactions and 27 had adverse events (infections/other adverse events). 29 had ADA to induce remission (28 CD and 1 UC), 24 after IFX; 10 entered remission, 12 had partial response and 7 had no response. All had maintenance; 19 required dose escalation. 12 children overall required hospitalisation due to drug toxicity. No deaths occurred with either IFX or ADA.

CONCLUSIONS

Complete accrual of the Scottish nationwide 'real-life' experience demonstrates moderate effectiveness of anti tumour necrosis factor agents in severe PIBD but duration of effect is limited; significant financial issues (drug cost-need for dose escalation and/or multiple biological usage) and safety issues exist.