Effect of Nuclear Factor κB Inhibition on Serotype 9 Adeno-Associated Viral (AAV9) Minidystrophin Gene Transfer to the mdx Mouse

Abstract

Gene therapy studies for Duchenne muscular dystrophy (DMD) have focused on viral vector-mediated gene transfer to provide therapeutic protein expression or treatment with drugs to limit dystrophic changes in muscle. The pathological activation of the nuclear factor (NF)-κB signaling pathway has emerged as an important cause of dystrophic muscle changes in muscular dystrophy. Furthermore, activation of NF-κB may inhibit gene transfer by promoting inflammation in response to the transgene or vector. Therefore, we hypothesized that inhibition of pathological NF-κB activation in muscle would complement the therapeutic benefits of dystrophin gene transfer in the mdx mouse model of DMD. Systemic gene transfer using serotype 9 adeno-associated viral (AAV9) vectors is promising for treatment of preclinical models of DMD because of vector tropism to cardiac and skeletal muscle. In quadriceps of C57BL/10ScSn-Dmd mdx /J (mdx) mice, the addition of octalysine (8K)-NF-κB essential modulator (NEMO)-binding domain (8K-NBD) peptide treatment to AAV9 minidystrophin gene delivery resulted in increased levels of recombinant dystrophin expression suggesting that 8K-NBD treatment promoted an environment in muscle tissue conducive to higher levels of expression. Indices of necrosis and regeneration were diminished with AAV9 gene delivery alone and to a greater degree with the addition of 8K-NBD treatment. In diaphragm muscle, high-level transgene expression was achieved with AAV9 minidystoophin gene delivery alone; therefore, improvements in histological and physiological indices were comparable in the two treatment groups. The data support benefit from 8K-NBD treatment to complement gene transfer therapy for DMD in muscle tissue that receives incomplete levels of transduction by gene transfer, which may be highly significant for clinical applications of muscle gene delivery.

Suppression of Activated FOXO Transcription Factors in the Heart Prolongs Survival in a Mouse Model of Laminopathies

“…It is also noteworthy that AAV9 constructs, despite their well-established tropism for cardiac myocytes, 54, 55 also transduce skeletal muscles, including the diaphragm, and to a lesser extent the liver. 56, 57 Consequently, the survival benefit observed in the Lmna −/− mice upon administration of AAV9- Foxo shRNA might be due to the effects of suppression of FOXO TF in other organs, such as the striated respiratory muscles, prevention of muscle atrophy, and the resultant improvement in respiratory efficiency, as shown in other models. 58, 59…”

The Interplay of Mitophagy and Inflammation in Duchenne Muscular Dystrophy

“…While there is promising evidence to help attenuate DMD disease pathology, most of these studies have been limited to DMD animal models and only few have progressed into clinical trials in DMD patients (recently reviewed in Verhaart et al [ 89 ]). Interestingly, it has been shown that treatment with NFκB inhibitors allowed for a higher mini-dystrophin expression induced via AAV treatment in mdx mice than without treatment, suggesting that it helps the transduction of the mini-dystrophin into the muscle [ 90 ]. This supports the idea of a combinatorial therapy for DMD that will involve anti-inflammatory/antioxidant treatment with a gene therapy to restore muscle stability and function.…”

Stem Cell Therapy in Muscle Degeneration

“…Short hairpin RNA carrier AAV9 has been successfully developed to target the major subunit of NF-›B (NF-›B/p65) and ameliorate muscle pathologic phenotype in mdx mice [160]. Finally, AAV9 mini-dystrophin gene delivery combined to the addition of octalysine (8K)-NF-›B essential modulator (NEMO)-Binding Domain (8K-NBD) peptide promoted a higher mini-dystrophin expression in skeletal muscle compared to AAV9 alone [161].…”