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Racial differences in the limb skeletal muscle transcriptional programs of patients with critical limb ischemia
Zoe S Terwilliger1,2, Terence E Ryan3, Emma J Goldberg1,2
1Diabetes and Obesity Institute, East Carolina University, Brody Medical Center, Greenville, NC, USA.
Insights
Critical limb ischemia (CLI), a severe peripheral artery disease (PAD) complication, affects Black individuals disproportionately. This study found common and race-unique molecular changes in CLI limb muscle, offering therapeutic targets.
Area of Science:
- Molecular biology
- Genomics
- Vascular biology
Background:
- Critical limb ischemia (CLI) is the most severe form of peripheral artery disease (PAD), leading to high morbidity and mortality.
- Black individuals experience a disproportionately higher incidence of CLI, necessitating research into underlying causes and tailored treatments.
Purpose of the Study:
- To investigate the molecular differences and similarities in limb muscle tissue between Black and White patients with CLI.
- To identify potential therapeutic targets for personalized treatment strategies in CLI patients.
Main Methods:
- Whole transcriptome shotgun sequencing (WTSS) was performed on gastrocnemius muscle from White and Black healthy volunteers and CLI patients.
- Enrichment analysis identified altered Reactome pathways.
- Quantitative reverse transcription polymerase chain reaction (RT-qPCR) validated key gene expression changes.
Main Results:
- Both White and Black CLI patients showed similar reductions in nuclear and mitochondrial genes and oxygen consumption, indicating a shared bioenergetic deficit.
- Unique alterations in Black CLI patients included changes in hemostasis, extracellular matrix organization, platelet regulation, and vascular wall interactions.
- Specific genes like MMP9, NUDT4P1, and GRIK2 showed unique expression patterns in Black patients' limb muscles.
Conclusions:
- CLI shares common molecular pathways across racial groups, primarily related to bioenergetic deficits.
- Distinct molecular signatures exist in the limb muscles of Black CLI patients, highlighting potential targets for race-specific therapies.
- This research is a foundational step towards developing personalized therapeutic options for CLI patients.
Abstract:
Critical limb ischemia (CLI) is the most severe manifestation of peripheral artery disease (PAD) and is characterized by high rates of morbidity and mortality. As with most severe cardiovascular disease manifestations, Black individuals disproportionately present with CLI. Accordingly, there remains a clear need to better understand the reasons for this discrepancy and to facilitate personalized therapeutic options specific for this population. Gastrocnemius muscle was obtained from White and Black healthy adult volunteers and patients with CLI for whole transcriptome shotgun sequencing (WTSS) and enrichment analysis was performed to identify alterations in specific Reactome pathways. When compared to their race-matched healthy controls, both White and Black patients with CLI demonstrated similar reductions in nuclear and mitochondrial encoded genes and mitochondrial oxygen consumption across multiple substrates, indicating a common bioenergetic paradigm associated with amputation outcomes regardless of race. Direct comparisons between tissues of White and Black patients with CLI revealed hemostasis, extracellular matrix organization, platelet regulation, and vascular wall interactions to be uniquely altered in limb muscles of Black individuals. Among traditional vascular growth factor signaling targets, WTSS revealed only Tie1 to be significantly altered from White levels in Black limb muscle tissues. Quantitative reverse transcription polymerase chain reaction validation of select identified targets verified WTSS directional changes and supports reductions in MMP9 and increases in NUDT4P1 and GRIK2 as unique to limb muscles of Black patients with CLI. This represents a critical first step in better understanding the transcriptional program similarities and differences between Black and White patients in the setting of amputations related to CLI and provides a promising start for therapeutic development in this population.
