Proto J D, Tang Y, Lu A, Chen W C W, Stahl E, Poddar M, Beckman S A, Robbins P D, Nidernhofer L J, Imbrogno K, Hannigan T, Mars W M, Wang B, Huard J
Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
1] Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA [2] Department of Bioengineering, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
Cell Death Dis. 2015 Apr 23;6(4):e1730. doi: 10.1038/cddis.2015.66.
The transcription factor nuclear factor κB (NF-κB)/p65 is the master regulator of inflammation in Duchenne muscular dystrophy (DMD). Disease severity is reduced by NF-κB inhibition in the mdx mouse, a murine DMD model; however, therapeutic targeting of NF-κB remains problematic for patients because of its fundamental role in immunity. In this investigation, we found that the therapeutic effect of NF-κB blockade requires hepatocyte growth factor (HGF) production by myogenic cells. We found that deleting one allele of the NF-κB subunit p65 (p65+/-) improved the survival and enhanced the anti-inflammatory capacity of muscle-derived stem cells (MDSCs) following intramuscular transplantation. Factors secreted from p65+/- MDSCs in cell cultures modulated macrophage cytokine expression in an HGF-receptor-dependent manner. Indeed, we found that following genetic or pharmacologic inhibition of basal NF-κB/p65 activity, HGF gene transcription was induced in MDSCs. We investigated the role of HGF in anti-NF-κB therapy in vivo using mdx;p65+/- mice, and found that accelerated regeneration coincided with HGF upregulation in the skeletal muscle. This anti-NF-κB-mediated dystrophic phenotype was reversed by blocking de novo HGF production by myogenic cells following disease onset. HGF silencing resulted in increased inflammation and extensive necrosis of the diaphragm muscle. Proteolytic processing of matrix-associated HGF is known to activate muscle stem cells at the earliest stages of repair, but our results indicate that the production of a second pool of HGF by myogenic cells, negatively regulated by NF-κB/p65, is crucial for inflammation resolution and the completion of repair in dystrophic skeletal muscle. Our findings warrant further investigation into the potential of HGF mimetics for the treatment of DMD.
转录因子核因子κB（NF-κB）/p65是杜兴氏肌营养不良症（DMD）炎症的主要调节因子。在小鼠DMD模型mdx小鼠中，抑制NF-κB可减轻疾病严重程度；然而，由于NF-κB在免疫中起基本作用，对患者进行NF-κB的治疗性靶向仍然存在问题。在本研究中，我们发现NF-κB阻断的治疗效果需要成肌细胞产生肝细胞生长因子（HGF）。我们发现，删除NF-κB亚基p65的一个等位基因（p65+/-）可提高肌肉来源干细胞（MDSC）在肌肉内移植后的存活率，并增强其抗炎能力。细胞培养中p65+/- MDSC分泌的因子以HGF受体依赖性方式调节巨噬细胞细胞因子表达。事实上，我们发现，在对基础NF-κB/p65活性进行基因或药物抑制后，MDSC中HGF基因转录被诱导。我们使用mdx;p65+/-小鼠研究了HGF在体内抗NF-κB治疗中的作用，发现骨骼肌中加速再生与HGF上调同时发生。这种抗NF-κB介导的营养不良表型在疾病发作后通过阻断成肌细胞从头产生HGF而得到逆转。HGF沉默导致膈肌炎症增加和广泛坏死。已知基质相关HGF的蛋白水解加工在修复的最早阶段激活肌肉干细胞，但我们的结果表明，由成肌细胞产生的另一池HGF受NF-κB/p65负调控，对于营养不良性骨骼肌的炎症消退和修复完成至关重要。我们的发现值得进一步研究HGF模拟物治疗DMD的潜力。
