Abstract Body: Introduction: Stroke causes deleterious changes in the liver, and patients with chronic liver disease are at an increased risk of ischemic stroke, suggesting the possibility of an unexplored liver-brain axis that modulates stroke outcomes. Here, using untargeted metabolomics and transcriptomics, we identified dysregulated hepatic oxalate metabolism following stroke. Oxalate is an end product of glyoxylate metabolism in the liver. Alanine glyoxylate aminotransferase (AGXT) is a liver-specific enzyme that detoxifies glyoxylate. Although the deleterious effects of oxalate in the kidneys are well established, the effects of hepatic oxalate overproduction on stroke recovery remain unknown.

Methods: We induced ischemic stroke in mice using an embolic model and evaluated liver function. To evaluate the consequences of stroke on both the liver and plasma metabolome, as well as the transcriptome, we conducted untargeted metabolomics and RNA sequencing. To address the clinical relevance, we assessed plasma oxalate in patients with stroke. To evaluate the causative role of hepatic oxalate overproduction in stroke, we utilized our CRISPR/Cas9 generated liver-specific Agxt^-/- mice, which exhibit increased circulating oxalate levels.

Results: We observed swollen, yellowish-brown livers and increased plasma transaminase levels in mice with stroke compared to sham controls (Figure 1 A-C). Distinct plasma and liver metabolic profiles, as demonstrated by principal component analyses, were observed in mice with stroke compared with sham controls (Figure 1 D-E). Proteomic enrichment analysis revealed significant enrichment of the glyoxylate and dicarboxylate metabolic pathways (Figure 1 F-G). RNA sequencing and histochemical analyses revealed enhanced neutrophil mediated oxidative stress in the livers of mice with stroke (Figure 2A-B). This was concomitant with increase in DNMT3B (an oxidative stress sensitive de novo methyltransferase), resulting in reduced hepatic AGXT levels, and higher plasma oxalate levels in patients and mice with stroke (Figure 2 C-G). In a proof-of-concept study, we found that stroke induction in Agxt^-/- mice resulted in increased brain oxalate levels, worse neurological outcomes and reduced sensorimotor recovery as compared to Agxt^+/+ mice (Figure 3).

Conclusion: We uncovered a novel pathway linking liver oxalate overproduction and exacerbated stroke outcomes, which could advance the translation of oxalate-lowering approaches to improve stroke outcomes.