Transcriptomic analysis of gastrocnemius muscle in Peripheral Artery Disease: differences according to response to walking exercise

Introduction: Walking exercise therapy is first line therapy for walking impairment in people with peripheral artery disease. However, up to 45% of people with PAD do not meaningfully respond to walking exercise interventions, defined as failure to improve six-minute walk distance by a clinically meaningful distance of 20 or more meters. Little is known about the biological mechanisms associated with poor response to walking exercise therapy in PAD. We hypothesized that baseline lower extremity skeletal muscle gene expression would be associated with responsiveness to walking exercise. Methods: Six participants with PAD who had a baseline gastrocnemius muscle biopsy were selected according to whether they responded to a walking exercise intervention (20 or more meter improvement in 6-minute walk at follow-up) and matched by age, sex, race, BMI, diabetes, exercise adherence, and type of exercise intervention (supervised or home-based) to six non-responders (< 20 m improvement). RNA-sequencing was performed on muscle biopsies, and transcriptomic differences between groups were assessed using limma, controlling for sex covariate (Model: expression ~ Group + sex), and applying Benjamini-Hochberg FDR correction. Results: Principal component (PC) analysis demonstrated significant correlation of PC1 with group [responder vs. non-responder] (p=1.38x10-18), suggesting distinct gene expression at baseline between responders and non-responders to walking exercise. Compared to non-responders, among genes over expressed in responders (Log2FC >1, FDR< 0.05), cellular respiration, oxidative phosphorylation, and aerobic electron transport chain gene ontologies were over-represented (FDR=3.38x10-20, FDR=3.94x10-20, and FDR=1.46x10-19, respectively). Compared to non-responders, genes over-expressed in responders that contributed to these gene ontologies included both mitochondrial- and nuclear-encoded mitochondrial transcripts. Compared to non-responders, genes under-expressed (Log2FC< -1, FDR< 0.05) in responders showed over-representation of KRAS signaling, TNF-alpha signaling, and inflammatory response pathways (p=0.003, p=0.03, and p=0.03, respectively). Conclusions: These results support the hypothesis that baseline gastrocnemius muscle gene expression may play a role in the response heterogeneity to walking exercise therapy in PAD. Future studies should confirm these findings in a larger cohort study to investigate whether these gene expression signatures can be developed into predictive biomarkers to identify PAD patients who would benefit most from walking exercise interventions. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.