Biology subjects

Leinenga, G.

Publications and source records attributed to Leinenga, G..

2 recordsLinked to original sources

bioRxiv2021

Claudin-5 binder enhances focused ultrasound-mediated opening in an in vitro blood-brain barrier model

RationaleThe blood-brain barrier (BBB) while functioning as a gatekeeper of the brain, impedes cerebral drug delivery. An emerging technology to overcome this limitation is focused ultrasound (FUS). When FUS interacts with intravenously injected microbubbles (FUS+MB), the BBB opens, transiently allowing the access of therapeutic agents into the brain. However, the ultrasound parameters need to be tightly tuned: when the acoustic pressure is too low there is no opening, and when it is too high, bleeds can occur. We therefore asked whether BBB permeability can be increased by combining FUS+MB with a second modality such that in a clinical setting lower acoustic pressures could be potentially used. MethodsGiven that FUS achieves BBB opening by the disruption of tight junction (TJ) proteins such as claudin-5 of brain endothelial cells, we generated a stable MDCK II cell line (eGFP-hCldn5-MDCK II) that expresses fluorescently tagged human claudin-5. Two claudin-5 binders, mC5C2 (a peptide) and cCPEm (a truncated form of an enterotoxin), that have been reported previously to weaken the barrier, were synthesized and assessed for their abilities to enhance the permeability of cellular monolayers. We then performed a comparative analysis of single and combination treatments. ResultsWe successfully generated a novel cell line that formed functional monolayers as validated by an increased transendothelial electrical resistance (TEER) reading and a low (< 0.2%) permeability to sodium fluorescein (376 Da). We found that the binders exerted a time- and concentration-dependent effect on BBB opening when incubated over an extended period, whereas FUS+MB caused a rapid barrier opening followed by recovery after 12 hours within the tested pressure range. Importantly, preincubation with cCPEm prior to FUS+MB treatment resulted in greater barrier opening compared to either FUS+MB or cCPEm alone as measured by reduced TEER values and an increased permeability to fluorescently labelled 40 kDa dextran (FD40). ConclusionThe data suggest that pre-incubation with clinically suitable binders to TJ proteins may be a general strategy to facilitate safer and more effective ultrasound-mediated BBB opening in cellular and animal systems and potentially also for the treatment of human diseases of the brain.

neuroscience↗

bioRxiv2021

A comparative study of the effects of Aducanumab and scanning ultrasound on amyloid plaques and behavior in the APP23 mouse model of Alzheimer disease

BackgroundAducanumab is an anti-amyloid-{beta} (A{beta}) antibody that achieved reduced amyloid pathology in Alzheimers disease (AD) trials, but it is controversial whether it also improved cognition. It has been claimed that this would require a sufficiently high cumulative dose of the antibody in the brain. Therapeutic ultrasound, in contrast, has only begun to be investigated in human AD clinical trials. We have previously shown that scanning ultrasound in combination with intravenously injected microbubbles (SUS), that temporarily and safely opens the blood-brain barrier (BBB), removes amyloid and restores cognition in APP23 mice. It has not been directly tested how the effects of SUS compare to immunotherapy or whether a combination therapy is more effective. MethodsIn a study comprising four treatment arms, we tested the efficacy of an Aducanumab analogue, Adu, in comparison to SUS, as well as a combination therapy in APP23 mice, using sham as a control (aged 13-22 months). The active place avoidance (APA) test was used to test spatial memory, and histology and ELISA were used to measure amyloid. Brain antibody levels were also determined. ResultsWe found that both Adu and SUS reduced the total plaque area in the hippocampus to a similar degree, with no additive effect in the combination treatment (SUS+Adu). Whereas there was only a trend towards a reduction for both Adu and SUS in the cortex, the combination trial yielded a statistically significant reduction compared to sham. Only the SUS and SUS+Adu groups included animals that had their plaque load reduced to below 1% from above 10%. There was a robust improvement in spatial memory for SUS+Adu only. In this group, when measured three days post-treatment, Adu levels were still 5-fold increased in the combination therapy compared to delivery of Adu on its own. Together, these findings suggest that SUS should be seriously considered as a treatment option for AD. Alternatively, a combination trial using Aducanumab together with ultrasound to increase brain levels of Aducanumab may be warranted, as the two approaches may engage different (albeit shared) clearance mechanisms.

neuroscience↗