Transthyretin Contributes to Hippocampal Blood-Brain Barrier Recovery Following Intestinal Inflammation, with Reduced Expression in Alzheimer's Disease

Authors

Xu, Z., Chen, J., Yu, J., Duan, J., Xie, Y., Gong, Y., Wang, P., Lei, X., Zhang, C., Zhao, X., Fan, Z., Xu, B., Zhang, J.

Abstract

Background: The blood-brain barrier (BBB) is increasingly recognized as an active immunoregulatory interface that responds dynamically to systemic inflammation. As intestinal inflammation can influence brain homeostasis through the gut-brain axis, the endogenous mechanisms that preserve BBB integrity during gut-derived inflammatory stress remain poorly understood. Methods and Results: We combined dextran sulfate sodium-induced colitis, fecal microbiota transplantation, aged mice, APP/PS1 mice, human Alzheimer's disease (AD) brain tissue, single-cell RNA sequencing, in vivo BBB permeability assays, and gain- and loss-of-function approaches to investigate adaptive neurovascular responses to gut inflammation and their mechanism in maintaining BBB integrity. Intestinal inflammation induced a region-specific adaptive response characterized by increased hippocampal vascular remodeling and partial restoration of BBB integrity following the initial inflammatory insult. Single-cell transcriptomic analysis identified a transthyretin (TTR)-enriched vascular-associated microglial state accompanying these neurovascular changes. Functional studies demonstrated that TTR contributes to maintaining BBB integrity by promoting endothelial homeostasis and limiting endothelial endocytosis, consistent with modulation of FcRn-associated transport pathways. This adaptive neurovascular response was progressively attenuated in aged mice and APP/PS1 mice and was accompanied by reduced vascular TTR expression in human AD brains. Conclusion: These findings identify TTR as a contributor of adaptive neurovascular homeostasis during gut-derived neuroinflammation. Impairment of this homeostatic response with aging and AD may contribute to persistent BBB dysfunction and chronic neuroinflammation, highlighting neurovascular resilience as a potential therapeutic target.

Preprint server: bioRxiv
The authors list and abstract were imported from bioRxiv on 06 Sep 2026.

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