Fruquintinib/HMPL-013 ameliorates cognitive impairments and pathology in a mouse model of cerebral amyloid angiopathy (CAA)

Cerebral proteome adaptations to amyloid angiopathy are prevented by carbonic anhydrase inhibitors

BACKGROUND

Cerebral amyloid angiopathy (CAA) is a hallmark of Alzheimer's disease (AD), linked to adverse effects of emerging AD treatments. We explored the molecular effects of CAA in mouse brain and evaluated how these could be prevented by two repurposed United States Food and Drug Administration (FDA) approved treatments.

METHODS

Brain proteomics was performed on the Tg-SwDI genetic mouse model carrying disease causing mutations and developing AD characteristic cognitive deficits and severe CAA. Cortical and hippocampal tissues from presymptomatic male and female mice were studied.

RESULTS

We identify a core of dysregulated proteins across studies, including established markers of AD as well as proteins indicative of astrogliosis and negative regulators of synaptic stability and function. Two FDA approved, repurposed carbonic anhydrase inhibitors (CAIs), acetazolamide and methazolamide, were effective in preventing these molecular adaptations.

DISCUSSION

The two drugs broadly prevent proteome adaptations to the detrimental genotype and retain glutamatergic synapse proteins significantly closer to wild-type levels.

HIGHLIGHTS

The brain proteome changes of mice with CAA are mapped. Cortical and hippocampal tissues from presymptomatic male and female mice are studied. Markers of AD, astrogliosis, and synaptic stability are dysregulated. Two CAI are effective in preventing these protein changes.

Calcium signaling in mitochondrial intermembrane space

The mitochondrial intermembrane space (IMS) is a highly protected compartment, second only to the matrix. It is a crucial bridge, coordinating mitochondrial activities with cellular processes such as metabolites, protein, lipid, and ion exchange. This regulation influences signaling pathways for metabolic activities and cellular homeostasis. The IMS harbors various proteins critical for initiating apoptotic cascades and regulating reactive oxygen species production by controlling the respiratory chain. Calcium (Ca2+), a key intracellular secondary messenger, enter the mitochondrial matrix via the IMS, regulating mitochondrial bioenergetics, ATP production, modulating cell death pathways. IMS acts as a regulatory site for Ca2+ entry due to the presence of different Ca2+ sensors such as MICUs, solute carriers (SLCs); ion exchangers (LETM1/SCaMCs); S100A1, mitochondrial glycerol-3-phosphate dehydrogenase, and EFHD1, each with unique Ca2+ binding motifs and spatial localizations. This review primarily emphasizes the role of these IMS-localized Ca2+ sensors concerning their spatial localization, mechanism, and molecular functions. Additionally, we discuss how these sensors contribute to the progression and pathogenesis of various human health conditions and diseases.

Cerebral Amyloid Angiopathy: An Undeniable Small Vessel Disease

Cerebral amyloid angiopathy (CAA) has been proven to be the most common pathological change in cerebral small vessel disease except arteriosclerosis. In recent years, with the discovery of imaging technology and new imaging markers, the diagnostic rate of CAA has greatly improved. CAA plays an important role in non-hypertensive cerebral hemorrhage and cognitive decline. This review comprehensively describes the etiology, epidemiology, pathophysiological mechanisms, clinical features, imaging manifestations, imaging markers, diagnostic criteria, and treatment of CAA to facilitate its diagnosis and treatment and reduce mortality.

Behavioral and Neuronal Characterizations, across Ages, of the TgSwDI Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder that currently affects as many as 50 million people worldwide. It is neurochemically characterized by an aggregation of β-amyloid plaques and tau neurofibrillary tangles that result in neuronal dysfunction, cognitive decline, and a progressive loss of brain function. TgSwDI is a well-studied transgenic mouse model of AD, but no longitudinal studies have been performed to characterize cognitive deficits or β-amyloid plaque accumulation for use as a baseline reference in future research. Thus, we use behavioral tests (T-Maze, Novel Object Recognition (NOR), Novel Object Location (NOL)) to study long-term and working memory, and immunostaining to study β-amyloid plaque deposits, as well as brain size, in hippocampal, cerebellum, and cortical slices in TgSwDI and wild-type (WT) mice at 3, 5, 8, and 12 months old. The behavioral results show that TgSwDI mice exhibit deficits in their long-term spatial memory starting at 8 months old and in long-term recognition memory at all ages, but no deficits in their working memory. Immunohistochemistry showed an exponential increase in β-amyloid plaque in the hippocampus and cortex of TgSwDI mice over time, whereas there was no significant accumulation of plaque in WT mice at any age. Staining showed a smaller hippocampus and cerebellum starting at 8 months old for the TgSwDI compared to WT mice. Our data show how TgSwDI mice differ from WT mice in their baseline levels of cognitive function and β-amyloid plaque load throughout their lives.