Alzheimer's disease can be treated: Why the delay?

Increasing cerebral blood flow improves cognition into late stages in Alzheimer's disease mice

Alzheimer's disease is associated with a 20-30% reduction in cerebral blood flow. In the APP/PS1 mouse model of Alzheimer's disease, inhibiting neutrophil adhesion using an antibody against the neutrophil specific protein Ly6G was recently shown to drive rapid improvements in cerebral blood flow that was accompanied by an improvement in performance on short-term memory tasks. Here, in a longitudinal aging study, we assessed how far into disease development a single injection of anti-Ly6G treatment can acutely improve short-term memory function. We found that APP/PS1 mice as old as 15-16 months had improved performance on the object replacement and Y-maze tests of spatial and working short-term memory, measured at one day after anti-Ly6G treatment. APP/PS1 mice at 17-18 months of age or older did not show acute improvements in cognitive performance, although we did find that capillary stalls were still reduced and cerebral blood flow was still increased by 17% in 21-22-months-old APP/PS1 mice given anti-Ly6G antibody. These data add to the growing body of evidence suggesting that cerebral blood flow reductions are an important contributing factor to the cognitive dysfunction associated with neurodegenerative disease. Thus, interfering with neutrophil adhesion could be a new therapeutic approach for Alzheimer's disease.

Potential improvement of survival statistics for glioblastoma multiforme (WHO IV)

The present-day treatment of a glioblastoma multiforme IV (glioblast) is by surgery, radiation, and chemotherapy. Unfortunately, the current treatment has not significantly improved the survival statistics of this tumor. There are now two relatively new surgical procedures that may improve the survival statistics of this malignancy. One of these procedures is the intraoperative use of the drug 5-aminovolumic acid (ALA), which fluoresces a red color in malignant brain tissue that is not observed in normal brain tissue. This allows a neurosurgeon to distinguish brain tissue infiltrated by malignant cells, thus allowing a more complete resection of the tumor. Another procedure that has the potential to improve the survival statistics of glioblasts is the use of the omentum. Direct placement of the omentum on a brain infiltrated by malignant cells would allow omental blood vessels, known to be completely clear of endothelial cells, to penetrate directly into the underlying brain. The blood flow through omental blood vessels could be expected to carry chemotherapeutic agents throughout the involved brain, thereby totally bypassing the blood–brain barrier. Combining a tumor resection using 5-ALA and placing the omentum on the brain may prove instrumental in improving the survival statistics of patients suffering from a glioblast.

Neutrophil adhesion in brain capillaries reduces cortical blood flow and impairs memory function in Alzheimer's disease mouse models

Cerebral blood flow (CBF) reductions in Alzheimer’s disease (AD) patients and related mouse models have been recognized for decades, but the underlying mechanisms and resulting consequences on AD pathogenesis remain poorly understood. In APP/PS1 and 5xFAD mice we found that an increased number of cortical capillaries had stalled blood flow as compared to wildtype animals, largely due to neutrophils that adhered in capillary segments and blocked blood flow. Administration of antibodies against the neutrophil marker Ly6G reduced the number of stalled capillaries, leading to an immediate increase in CBF and to rapidly improved performance in spatial and working memory tasks. This study identified a novel cellular mechanism that explains the majority of the CBF reduction seen in two mouse models of AD and demonstrated that improving CBF rapidly improved short-term memory function. Restoring cerebral perfusion by preventing neutrophil adhesion may provide a novel strategy for improving cognition in AD patients.