Walking performance is positively correlated to calf muscle fiber size in peripheral artery disease subjects, but fibers show aberrant mitophagy: An observational study

Sarah H. White, Mary M. McDermott, Robert L. Sufit, Kate Kosmac, Alex W. Bugg, Marta Gonzalez-Freire, Luigi Ferrucci, Lu Tian, Lihui Zhao, Ying Gao, Melina R. Kibbe, Michael H. Criqui, Christiaan Leeuwenburgh, Charlotte A. Peterson

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Abstract

Background: Patients with lower extremity peripheral artery disease (PAD) have decreased mobility, which is not fully explained by impaired blood supply to the lower limb. Additionally, reports are conflicted regarding fiber type distribution patterns in PAD, but agree that skeletal muscle mitochondrial respiration is impaired. Methods: To test the hypothesis that reduced muscle fiber oxidative activity and type I distribution are negatively associated with walking performance in PAD, calf muscle biopsies from non-PAD (n = 7) and PAD participants (n = 26) were analyzed immunohistochemically for fiber type and size, oxidative activity, markers of autophagy, and capillary density. Data were analyzed using analysis of covariance. Results: There was a wide range in fiber type distribution among subjects with PAD (9-81 % type I fibers) that did not correlate with walking performance. However, mean type I fiber size correlated with 4-min normal- and fastest-paced walk velocity (r = 0.4940, P = 0.010 and r = 0.4944, P = 0.010, respectively). Although intensity of succinate dehydrogenase activity staining was consistent with fiber type, up to 17 % of oxidative fibers were devoid of mitochondria in their cores, and the core showed accumulation of the autophagic marker, LC3, which did not completely co-localize with LAMP2, a lysosome marker. Conclusions: Calf muscle type I fiber size positively correlates with walking performance in PAD. Accumulation of LC3 and a lack of co-localization of LC3 with LAMP2 in the area depleted of mitochondria in PAD fibers suggests impaired clearance of damaged mitochondria, which may contribute to reduced muscle oxidative capacity. Further study is needed to determine whether defective mitophagy is associated with decline in function over time, and whether interventions aimed at preserving mitochondrial function and improving autophagy can improve walking performance in PAD.

Original languageEnglish (US)
Article number284
JournalJournal of Translational Medicine
Volume14
Issue number1
DOIs
StatePublished - Sep 29 2016
Externally publishedYes

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Keywords

  • Calf muscle
  • Fiber type
  • Mitochondria
  • Mitophagy
  • Peripheral artery disease

ASJC Scopus subject areas

  • Medicine(all)
  • Biochemistry, Genetics and Molecular Biology(all)

Cite this

White, S. H., McDermott, M. M., Sufit, R. L., Kosmac, K., Bugg, A. W., Gonzalez-Freire, M., Ferrucci, L., Tian, L., Zhao, L., Gao, Y., Kibbe, M. R., Criqui, M. H., Leeuwenburgh, C., & Peterson, C. A. (2016). Walking performance is positively correlated to calf muscle fiber size in peripheral artery disease subjects, but fibers show aberrant mitophagy: An observational study. Journal of Translational Medicine, 14(1), [284]. https://doi.org/10.1186/s12967-016-1030-6