Interplay of IKK/NF-κB signaling in macrophages and myofibers promotes muscle degeneration in Duchenne muscular dystrophy
Swarnali Acharyya, … , Albert S. Baldwin, Denis C. Guttridge
Swarnali Acharyya, … , Albert S. Baldwin, Denis C. Guttridge
Published April 2, 2007
Citation Information: J Clin Invest. 2007;117(4):889-901. https://doi.org/10.1172/JCI30556.
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Research Article Inflammation

Interplay of IKK/NF-κB signaling in macrophages and myofibers promotes muscle degeneration in Duchenne muscular dystrophy

Abstract

Duchenne muscular dystrophy (DMD) is a lethal X-linked disorder associated with dystrophin deficiency that results in chronic inflammation and severe skeletal muscle degeneration. In DMD mouse models and patients, we find that IκB kinase/NF-κB (IKK/NF-κB) signaling is persistently elevated in immune cells and regenerative muscle fibers. Ablation of 1 allele of the p65 subunit of NF-κB was sufficient to improve pathology in mdx mice, a model of DMD. In addition, conditional deletion of IKKβ in mdx mice elucidated that NF-κB functions in activated macrophages to promote inflammation and muscle necrosis and in skeletal muscle fibers to limit regeneration through the inhibition of muscle progenitor cells. Furthermore, specific pharmacological inhibition of IKK resulted in improved pathology and muscle function in mdx mice. Collectively, these results underscore the critical role of NF-κB in the progression of muscular dystrophy and suggest the IKK/NF-κB signaling pathway as a potential therapeutic target for DMD.

Authors

Swarnali Acharyya, S. Armando Villalta, Nadine Bakkar, Tepmanas Bupha-Intr, Paul M.L. Janssen, Micheal Carathers, Zhi-Wei Li, Amer A. Beg, Sankar Ghosh, Zarife Sahenk, Michael Weinstein, Katherine L. Gardner, Jill A. Rafael-Fortney, Michael Karin, James G. Tidball, Albert S. Baldwin, Denis C. Guttridge

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Figure 1

NF-κB activity in dystrophic muscle is localized to both muscle and immune cells.

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NF-κB activity in dystrophic muscle is localized to both muscle and immu...
(A–C) Muscle nuclear extracts from 5-week-old WT C57BL/10 and 3- and 5-week-old mdx mice (A), 5-week-old WT and mdx mice (B), or 7-week-old WT, mdx, and DKO mice (C) were used in EMSA for NF-κB and Oct-1. Supershift assays were performed on mdx muscle extracts using antibodies against p65 and p50. Arrowheads denote shifted subunits. (D) IKK assays performed with IκBα WT and mutant (double serine to threonine [SS/TT]) or p65 WT and mutant (serine to alanine [S/A]) substrates using gastrocnemius muscle lysates from 7-week-old WT or mdx mice. Immunoprecipitates were probed for IKKγ as a loading control. Western blots are shown for p-IKK, p-IκBα, IκBα, p-p65, and p65. GST, glutathione-S-transferase. (E) Gastrocnemius muscles from 7-week-old WT or mdx mice were immunostained for p-p65. Scale bars: 50 μm. Black arrowheads denote immune cells, and blue arrowheads indicate regenerating fibers. (F) Muscles from either 4- or 7-week-old mdx mice were double stained with p-p65 (green) and CD68 (red) or p-p65 and E-MyHC (red), respectively. Scale bars: 20 μm. (G) H&E staining and p-p65 immunohistochemistry were performed on muscle biopsies from healthy controls and age-matched DMD patients (n = 4). Scale bar: 50 μm.