# Molecular Dissection of Permanent vs. Reperfused Ischemia: Multi-Omics Divergence and Precision Therapeutic Implications

## TL;DR

This study compares molecular changes in cerebral ischemia with and without reperfusion, revealing distinct patterns that could lead to better stroke treatments.

## Contribution

The study reveals unique proteomic and transcriptomic signatures of reperfusion injury, highlighting post-transcriptional regulation and novel therapeutic targets.

## Key findings

- IRI shows extensive proteomic changes (160 proteins) with minimal transcriptional changes (3 genes), indicating post-transcriptional regulation.
- IRI uniquely activates neuroprotective genes and reperfusion-related pathways, including upregulation of Mmp3 and 72 specific proteins.
- Transcriptomic and proteomic profiles have low correlation (r = 0.014), emphasizing the role of protein dynamics in IRI.

## Abstract

Objective: Cerebral ischemia–reperfusion injury (IRI) is a distinct pathological phase that differs from permanent ischemia (IR) in that it triggers secondary damage despite the restoration of blood flow. The primary objective of this study is to comprehensively characterize and compare the molecular signatures—such as differential gene expression, protein activation, and metabolic alterations—between IRI and IR. By doing so, we aim to identify key pathways and biomarkers that specifically drive IRI and IR pathology, thereby providing novel therapeutic targets to mitigate reperfusion-induced damage in stroke and related neurological conditions. Methods: We employed an integrated transcriptomic and proteomic approach to compare a permanent ischemia model (IR, 24 h ischemia) with a reperfusion model (IRI, 1 h ischemia + 24 h reperfusion), using SHAM-operated animals as controls. Results: Our results demonstrate a profound decoupling between the transcriptome and proteome in IRI. While IRI induced extensive proteomic alterations (160 changed proteins in IRI vs. IR), transcriptional changes were minimal (3 genes), indicating dominant post-transcriptional regulation. Both IR and IRI activated shared inflammatory responses (e.g., Saa3, upregulated 14.33-fold in IRI/SHAM) and metabolic shifts (Gapdh, downregulated 4.03-fold). However, IRI uniquely upregulated neuroprotective genes (Arc, Npas4), activated a specific set of reperfusion-related pathways (72 proteins), and exhibited distinct extracellular matrix remodeling (Mmp3, upregulated 11.24-fold in IR/SHAM). The overall correlation between transcriptomic and proteomic dynamics was remarkably low (r = 0.014), underscoring the importance of translation and protein decay mechanisms. Conclusions: This study redefines IRI not merely as an exacerbation of ischemic damage but as a unique adaptive molecular trajectory. We identify Pisd-ps3 and Saa3 as potential therapeutic targets and show that proteomic signatures can stratify injury phases. These findings advance the prospects of precision therapeutics aimed at neuroprotection and immunomodulation in ischemic stroke.