Omics & gene networks

Transcriptomic characterisation of recurrent exertional rhabdomyolysis using bulk and single nuclei RNA Seq in muscle and blood of Thoroughbred horses

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Abstract

Abstract Text: Recurrent exertional Rhabdomyolysis (RER) is a syndrome characterised by repeated episodes of exercise-induced muscle soreness and cramping. It involves muscle fibre necrosis, increased serum activity of creatine kinase and aspartate aminotransferase, and, on occasion, myoglobinuria, renal failure and death. Horses are particularly susceptible, 5-7% prevalence in Thoroughbreds (TBs). ER has a genetic component (h2=0.39-0.49) and is a multifactorial complex disease influenced by genetic and environmental factors. Here, we have investigated the transcriptomic signature of RER by cases and controls using bulk RNA-seq in blood from 26 TBs (14 cases, 12 controls - systemic response) and biopsied semimembranosus muscles (SM) (8 cases and 13 controls - local response). Nuclei were also isolated from SMs for single nuclei sequencing (5 cases, 8 controls) using 10X technology. In snRNA-Seq analysis we identified ten cell types and observed differences in muscle fibre proportions between healthy and myopathy samples, particularly glycolytic and oxidative fibres. In these cell types in myopathy samples, 75 and 69 DEGs were downregulated and 241 and 293 upregulated respectively (padj≤0.05). Functional analyses of these DEGs showed significant (p≤0.05) downregulation of 12 biological process', primarily involved in metabolic processes, lipid processing and extracellular matrix organisation. From bulk RNA-seq, we identified 91 DEGs in blood (padj≤0.05), enriched for calcium ion binding and ATP kinase activity. In muscle, we identified 988 DEGs (padj≤0.05) enriched for cell communication and metabolic processes. Both tissues were functionally enriched for retrotransposition and transposition and between the two, 45 overlapping DEGs were enriched across the three analyses. These functions have been previously associated with skeletal muscle ageing and adaptation to stress. We conducted a co-expression analysis of DE transposable elements with protein coding DEGs to functionally interpret the role of mobile genetic elements in RER. We found strong correlation between RER DEGs and transposable elements that have been previously associated with exercise tolerance and adaptation to high intensity exercise in human studies. Oxidative fibre DEGs from snRNA-seq, 69 downregulated and 293 upregulated in myopathies, were functionally enriched for lipid transport and localisation and fibroblast cell cluster DEGs for metabolism and lipid transport. Our results suggest a role of metabolic processing and transposable elements in RER susceptibility perhaps through genomic adaptability to exercise-induced stress. The findings from bulk RNA-seq combined with snRNA-seq provide a high-resolution view of the genomic elements implicated in RER along with the broader regulatory components to provide a more comprehensive understanding of this complex condition. Identifying overlapping DEGs in snRNA-Seq and bulk RNA-Seq also lends hope to the identification of genomic biomarkers of disease, improving diagnostic potential. Improving understanding of the underlying mechanisms would provide a framework for future targeted breeding and management strategies to reduce the prevalence of RER in the equine population.

Keywords: 2026

How to Cite:

Attree, E., Cuffe, C., Hodges, H., McCue, M., Clark, E., Piercy, R. & Psifidi, A., (2026) “Transcriptomic characterisation of recurrent exertional rhabdomyolysis using bulk and single nuclei RNA Seq in muscle and blood of Thoroughbred horses”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2286457. doi: https://doi.org/10.31274/wcgalp.24015

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