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Fibrosis Distinguishes Critical Limb Ischemia Patients from Claudicants in a Transcriptomic and Histologic Analysis
Guangzhi Cong1,2, Xiangdong Cui1, Ricardo Ferrari1
1Department of Surgery, University of Pittsburgh Medical Centre, Pittsburgh, PA 15217, USA.
Insights
Critical limb ischemia (CLI) involves unique gene expression linked to fibrosis, unlike intermittent claudication (IC). Transcriptomic analysis reveals fibrosis pathways, including TGFβ, as a key feature for novel CLI therapies in peripheral arterial disease (PAD).
Area of Science:
- Vascular Biology
- Genomics
- Molecular Medicine
Background:
- Peripheral arterial disease (PAD) can lead to critical limb ischemia (CLI), often without prior intermittent claudication (IC).
- Understanding the molecular differences between CLI and IC is crucial for developing targeted therapies.
Purpose of the Study:
- To identify CLI-specific gene expression pathways, with a focus on fibrosis.
- To differentiate the molecular profiles of CLI, IC, and healthy controls using transcriptomic analysis.
Main Methods:
- Transcriptomic analysis of muscle biopsies from derivation and validation cohorts.
- Pathway enrichment analysis to identify differentially expressed genes and associated biological processes.
- Receiver operating curve (ROC) analysis to assess the diagnostic accuracy of fibrosis-related genes.
Main Results:
- CLI patients exhibited unique gene expression profiles compared to controls and IC patients.
- Enriched pathways in CLI included TGFβ signaling, collagen deposition, and VEGF signaling, not observed in IC.
- Fibrosis markers demonstrated high diagnostic accuracy (AUC > 0.75) for distinguishing CLI from IC and controls.
Conclusions:
- Transcriptomic analysis identifies distinct fibrosis pathways, involving TGFβ, as a novel molecular feature of CLI.
- Histological confirmation supports fibrosis as a significant characteristic of CLI.
- These findings suggest fibrosis pathways as potential therapeutic targets for CLI in PAD.
Abstract:
Most patients with critical limb ischemia (CLI) from peripheral arterial disease (PAD) do not have antecedent intermittent claudication (IC). We hypothesized that transcriptomic analysis would identify CLI-specific pathways, particularly in regards to fibrosis. Derivation cohort data from muscle biopsies in PAD and non-PAD (controls) was obtained from the Gene Expression Omnibus (GSE120642). Transcriptomic analysis indicated CLI patients (N = 16) had a unique gene expression profile, when compared with non-PAD controls (N = 15) and IC (N = 20). Ninety-eight genes differed between controls and IC, 2489 genes differed between CLI and controls, and 2783 genes differed between CLI and IC patients. Pathway enrichment analysis showed that pathways associated with TGFβ, collagen deposition, and VEGF signaling were enriched in CLI but not IC. Receiver operating curve (ROC) analysis of nine fibrosis core gene expression revealed the areas under the ROC (AUC) were all >0.75 for CLI. Furthermore, the fibrosis area (AUC = 0.81) and % fibrosis (AUC = 0.87) in validation cohort validated the fibrosis discrimination CLI from IC and control (all n = 12). In conclusion, transcriptomic analysis identified fibrosis pathways, including those involving TGFβ, as a novel gene expression feature for CLI but not IC. Fibrosis is an important characteristic of CLI, which we confirmed histologically, and may be a target for novel therapies in PAD.
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