Franciosa, S. A. | Search bioRxiv

bioRxiv2026

Reducing Neutrophil Sialic Acid Residues Alleviates Cerebral Hypoperfusion in Alzheimer's Models

Objective: Dysregulation of the immune system is increasingly recognized as a contributor to Alzheimer's disease (AD) progression, partly through neutrophil adhesion to the cerebral vasculature, which promotes hypoperfusion in AD. Because sialic acid (SA) residues on membrane glycoproteins regulate neutrophil-endothelial interactions, we investigated whether neutrophil sialylation is altered in AD and whether reducing it improves cerebral vascular function. Approach and Results: Lectin blots of isolated neutrophils showed increased SA levels in two AD mouse models, 5xFAD and APP-SAA. We identified 2,3 sialyltransferase-IN-1 as a small-molecule inhibitor that reduces sialylation in vivo. Treating 5xFAD mice with this inhibitor decreased SA on neutrophil membranes, increased cerebral blood flow, and reduced capillary stalling. Leukocytes from patients with preclinical AD and mild cognitive impairment also had higher SA levels than those from age-matched healthy controls. Conclusions: Elevated terminal sialylation of neutrophil glycoproteins contributes to capillary stalling and cerebral hypoperfusion in AD. Neutrophil sialylation may serve as both a biomarker and a therapeutic target for improving cerebral blood flow and slowing disease progression.

neuroscience↗

bioRxiv2026

Progranulin haploinsufficiency remodels the cerebral microvasculature and neurovascular unit

Progranulin (PGRN) deficiency is a major genetic cause of frontotemporal dementia (FTD), yet its impact on cerebrovascular function remains understudied. Here, we show that PGRN deficiency contributes to cerebral microvascular perfusion and induces alterations within the neurovascular unit. In vivo two-photon imaging revealed increased capillary stalling and in cerebral blood flow (CBF), driven in part by increased leucocyte-capillary interactions and elevated endothelial ICAM-1 expression. Transcriptomic profiling of isolated cerebral microvessels demonstrated coordinated upregulation of immune and extracellular matrix pathways alongside suppression of angiogenic and stress-response programs, indicative of endothelial activation. Cross-species analyses identified partial conservation of these vascular signatures in endothelial cells from human FTD-GRN patients, associated with dysregulated angiogenic and inflammatory signaling. Despite altered tight junction organization and reduced solute carrier transporter expression, blood-brain barrier (BBB) permeability remained largely intact, suggesting functional rather than structural BBB disruption, as well as. These vascular changes were accompanied by broad alterations in the morphology of astrocytes, pericytes, and microglial cells. Here we determined a novel role for progranulin in cerebrovascular homeostasis and established microvascular dysfunction as a key driver of FTD-GRN pathophysiology.

neuroscience↗