title: L-arginine decreases inflammation and modulates the nuclear factor-kappaB/matrix metalloproteinase cascade in mdx muscle fibers.
abstract: Duchenne muscular dystrophy (DMD) is a lethal, X-linked disorder associated with dystrophin deficiency that results in chronic inflammation, sarcolemma damage, and severe skeletal muscle degeneration. Recently, the use of L-arginine, the substrate of nitric oxide synthase (nNOS), has been proposed as a pharmacological treatment to attenuate the dystrophic pattern of DMD. However, little is known about signaling events that occur in dystrophic muscle with l-arginine treatment. Considering the implication of inflammation in dystrophic processes, we asked whether L-arginine inhibits inflammatory signaling cascades. We demonstrate that L-arginine decreases inflammation and enhances muscle regeneration in the mdx mouse model. Classic stimulatory signals, such as proinflammatory cytokines interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha, are significantly decreased in mdx mouse muscle, resulting in lower nuclear factor (NF)-kappaB levels and activity. NF-kappaB serves as a pivotal transcription factor with multiple levels of regulation; previous studies have shown perturbation of NF-kappaB signaling in both mdx and DMD muscle. Moreover, L-arginine decreases the activity of metalloproteinase (MMP)-2 and MMP-9, which are transcriptionally activated by NF-kappaB. We show that the inhibitory effect of L-arginine on the NF-kappaB/MMP cascade reduces beta-dystroglycan cleavage and translocates utrophin and nNOS throughout the sarcolemma. Collectively, our results clarify the molecular events by which L-arginine promotes muscle membrane integrity in dystrophic muscle and suggest that NF-kappaB-related signaling cascades could be potential therapeutic targets for DMD management.
authors.affiliation: INSERM ERI 25 Muscle et Pathologies, CHU A. de Villeneuve, Université de Montpellier1, EA 4202, 34295 Montpellier Cedex 5, France.
authors.forename: Karim
authors.initials: K
authors.lastname: Hnia
authors.forename: Jérôme
authors.initials: J
authors.lastname: Gayraud
authors.forename: Gérald
authors.initials: G
authors.lastname: Hugon
authors.forename: Michèle
authors.initials: M
authors.lastname: Ramonatxo
authors.forename: Sabine
authors.initials: S
authors.lastname: De La Porte
authors.forename: Stefan
authors.initials: S
authors.lastname: Matecki
authors.forename: Dominique
authors.initials: D
authors.lastname: Mornet
mesh_terms: D000818:Animals; D001120:Arginine / Q000494:pharmacology*; D007249:Inflammation / Q000378:metabolism / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000502:physiology; D020778:Matrix Metalloproteinase 2 / Q000502:physiology*; D020780:Matrix Metalloproteinase 9 / Q000502:physiology*; D051379:Mice; D018101:Mice, Inbred mdx; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D018482:Muscle, Skeletal / Q000473:pathology*; D020388:Muscular Dystrophy, Duchenne / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D016328:NF-kappa B / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D012038:Regeneration; D015398:Signal Transduction
chemical_list: D016328:NF-kappa B; D001120:Arginine; D019001:Nitric Oxide Synthase; D020778:Matrix Metalloproteinase 2; C522362:Mmp2 protein, mouse; D020780:Matrix Metalloproteinase 9; C501830:Mmp9 protein, mouse