L. A. Carpenter1, J. R. Thompson1, D. M. Ha1, S. A. Swanson1, J. M. Johanning1,2, E. A. Papoutsi1, P. Koutakis1, D. A. Miserlis1, I. I. Pipinos1,2, G. P. Casale1 1University Of Nebraska Medical Center,Department Of Surgery,Omaha, NE, USA 2VA Nebraska-Western Iowa Health Care System,Omaha, NE, USA
Introduction:
Peripheral arterial disease (PAD) is characterized by limb dysfunction in association with cycles of ischemia/reperfusion that cause oxidative damage to muscles of the lower leg. Studies evaluating the contribution of inflammation to the pathology of PAD identified increased serum concentrations of tumor necrosis factor alpha (TNF-alpha), interleukin 6 and monocyte chemoattractant protein-1. Recently, we demonstrated increased concentrations of cytokines including TNF-alpha, transforming growth factor beta1 (TGF-beta1) and chemokine (c-c motif) ligand 5 (CCL5) in the gastrocnemius of PAD patients. In this study, we tested the hypothesis that these increases were due to increased gene expression in the gastrocnemius.
Methods:
Gastrocnemius biopsies were collected from PAD patients (N=24) at Fontaine Stage II and controls (N=18) with no leg impairment. Muscle homogenates were analyzed by qPCR for TNF-alpha, TGF-beta1 and CCL5 gene transcripts expressed as fold change in relation to myosin heavy chain transcripts.
Results:
TNF-alpha, TGF-beta1 and CCL5 transcripts were increased in PAD patients (mean +/- s.e.; 1.07 +/- 0.31, 12.87 +/- 3.38 and 3.01 +/- 0.99, respectively) compared to controls (0.02 +/- 0.01, 0.56 +/- 0.25 and 0.15 +/- 0.10) at p values of 0.003, 0.001 and 0.009. Relative changes in these transcripts are in close agreement with changes in protein expression determined in our previous study.
Conclusion:
The data support increased, local expression of the genes for TNF-alpha, TGF-beta1 and CCL5 in the gastrocnemius of PAD patients and identify a local cytokine milieu that suppresses myoblast differentiation and promotes fibrotic replacement of oxidatively damaged and necrotic myofibers.