FOLLISTATIN GENE THERAPY
Follistatin is being studied for its role in regulation of muscle growth in mice, as an antagonist to myostatin (also known as GDF-8, a TGF superfamily member) which inhibits excessive muscle growth. Lee & McPherron demonstrated that inhibition of GDF-8, either by genetic elimination or by increasing the amount of follistatin, resulted in greatly increased muscle mass.
In 2009, research with monkeys demonstrated that regulating follistatin via gene therapy also resulted in muscle growth and increases in strength. This research paves the way for human clinical trials and inclusion body myositis.
A study has also shown that increased levels of follistatin, by leading to increased muscle mass of certain core muscular groups, can increase life expectancy in cases of spinal muscular atrophy in animal models.
It is also being investigated for its involvement in polycystic ovary syndrome though there is debate as to its direct role in this infertility disease.
Follistatin Gene Therapy significantly reduces inflammatory pathways and pro-inflammatory markers including Inflammatory Cytokines - IL-1, IL-6, and Tumor Necrosis Factor (TNF-alpha). Follistatin (myostatin inhibition) increases the skeletal muscle mass and prevent muscle degeneration, regardless of the type of muscular dystrophy.
Undersea Hyperb Med. 2012 Nov-Dec;39(6):1111-4.
Therapeutic effect of hyperbaric oxygen on inclusion body myositis
Philadelphia College of Osteopathic Medicine, Philadelphia, Pennsylvania, USA.
An inflammatory myopathy, inclusion body myositis (IBM) presents with progressive muscle weakness against a background of elevated creatine kinase and diffuse endomysial damage. Typically occurring in patients greater than 50 years of age, it is commonly misdiagnosed as polymyositis or other rheumatological disease and is often ineffectively treated with steroids . The approach to IBM is frequently a clinical challenge due to its unique and often aberrant response to common treatment modalities. Here we report an apparent improvement in the clinical course of and associated laboratory findings in a patient with co-existing IBM following the use of hyperbaric oxygen therapy as an adjunct for managing ischemic colitis.
Clin Exp Med. 2014 Jun 13. [Epub ahead of print]
Effects of chronic hepatitis C genotype 1 and 4 on serum activins and follistatin in treatment naïve patients and their correlations with interleukin-6, tumour necrosis factor-α, viral load and liver damage
1Laboratory Medicine Department, Faculty of Applied Medical Sciences, Umm Al-Qura University, PO Box 7607, Al Abdeyah, Makkah, KSA, Bassem.firstname.lastname@example.org.
The importance of activins and follistatin in liver diseases has recently emerged. The aim of the present study was to measure the influence of chronic infection with viral hepatitis C (CHC) genotype 1 and 4 on serum levels of activin-A, activin-B and follistatin, and to determine their correlations with viral load, liver damage, interleukin-6 (IL-6) and tumour necrosis factor (TNF)-α. Sera samples collected from 20 male and 20 female treatment naïve CHC genotype 1 and 4 Saudi patients (ten males and ten females for each genotype), and 40 gender- and age-matched healthy participants were analysed for activin-A, activin-B and follistatin using enzyme-linked immunosorbent assay and their levels were correlated with IL-6, TNF-α, viral load and AST platelet ratio index (APRI).
Serum activin-A, activin-B, IL-6 and TNF-α were significantly increased, while serum follistatin was significantly decreased, in both genders of CHC patients compared with control subjects, In both viral genotypes, activin-A was strongly and positively correlated with the viral load, APRI, IL-6 and TNF-α, and negatively with albumin (P < 0.01). Activin-B showed the same correlations of activin-A only in CHC genotype 1 patients, but it was weaker than activin-A. No correlation was detected with follistatin. Serum activins, particularly activin-A, and follistatin are significantly altered by CHC genotype 1 and 4. This dysregulation of activins/follistatin axis may be associated with viral replication, host immune response and liver injury. Further studies are needed to illustrate the definite role(s) and clinical value of activins and follistatin in CHC.
J Neuroimmunol. 2011 Sep 15;238(1-2):96-103. doi: 10.1016/j.jneuroim.2011.08.003. Epub 2011 Aug 31.
Low and dysregulated production of follistatin in immune cells of relapsing-remitting multiple sclerosis patients
1Neuroimmunology Laboratory, Department of Neurology, Tel Aviv Sourasky Medical Center, Tel Aviv University, Tel Aviv, Israel.
One of the mechanisms known to play a key role in neuronal and oligodendroglial fate specification of neural stem cells (NSCs) is restriction of bone morphogenic proteins (BMP) signaling by BMP antagonists. Here, we demonstrate that follistatin mRNA and protein secreted levels in peripheral blood mononuclear cells (PBMCs) of relapsing-remitting multiple sclerosis (RR-MS) patients are significantly reduced compared to healthy controls (HC). We also observed a different profile of regulation mechanisms. Follistatin was similarly expressed and secreted by T lymphocytes and monocytes among the PBMCs of HC, and follistatin upregulation of HC was subjected to stimulation with both LPS and TNF-α. Among PBMCs of RR-MS patients, however, follistatin was found to be downregulated in their monocytes and unresponsive to stimulation with either LPS or TNF-α.
Our results may shed some light on the mechanisms involved in remyelination failure in MS, which may be related to the inability of RR-MS patients' immune cells to provide a sufficient pro-neurogenic and oligodendrogenic niche, by expressing and secreting follistatin, in addition to the previously described noggin reduced expression. Our results indicate that the low expression of follistatin in immune cells of patients with RR-MS is a result of the altered immunoregulation of monocytes in these patients.
J Strength Cond Res. 2011 Aug;25(8):2283-92. doi: 10.1519/JSC.0b013e3181f1592e.
Muscular hypertrophy and changes in cytokine production after eccentric training in the rat skeletal muscle
1Laboratory of Health and Sports Sciences, Center for Liberal Arts, Meiji Gakuin University, Kanagawa, Japan.
We investigated the time course effects of eccentric training on muscular size, strength, and growth factor/cytokine production by using an isokinetic-exercise system for rats. Male Wistar rats (n = 34) were randomly assigned into 4 groups: 5 session eccentric-training group (ECC5S, n = 10); 5 session sham-operated group (CON5S, n = 10); 10 session eccentric-training group (ECC10S, n = 7); 10 session sham-operated group (CON10S, n = 7). In each group, a session of either training or sham operation was performed every 2 days. The training consisted of 4 sets of forced dorsiflexion (5 repetitions) combined with electric stimulation of plantar flexors. The wet weight of medial gastrocnemius muscle did not increase significantly after 5 sessions of training, whereas that after 10 sessions of training significantly increased with a concomitant increase in the cross-sectional area (CSA) of muscle fibers (weight, p < 0.05; fiber CSA, p < 0.001). Interleukin (IL)-6 in ECC5S and ECC10S groups showed significant increases (p < 0.01), whereas those of tumor necrosis factor (TNF)-α and IL-10 did not. The phospho-stat-3 showed a significant increase in ECC10S (p < 0.001) but not in ECC5S. Myostatin and follistatin also showed significant differences only between ECC10S and CON10S (p < 0.05).
The results showed that repeated sessions of eccentric training for 20 days cause increases in muscular size and strength associated with increases in IL-6, follistatin, phospho-stat-3, and a decrease in myostatin. The delayed responses of IL-6, myostatin, phospho-stat-3, and follistatin would be due to the chronic effects of repeated training and possibly important for muscular hypertrophy.
J Pharmacol Exp Ther. 2013 Mar;344(3):616-23. doi: 10.1124/jpet.112.201491. Epub 2012 Dec 17.
An engineered human follistatin variant: insights into the pharmacokinetic and pharmocodynamic relationships of a novel molecule with broad therapeutic potential
1Department of Drug Disposition Development/Commercialization, Lilly Research Laboratories, Indianapolis, IN 46285, USA.
Human follistatin is a regulatory glycoprotein with widespread biologic functions, including antiinflammatory activities, wound-healing properties, and muscle-stimulating effects. The role of follistatin in a wide range of biologic activities shows promise for potential clinical application, which has prompted considerable interest in the investigation of the protein as a potential disease-modifying agent. In spite of this potential, the development of follistatin as a broad use biotherapeutic has been severely hindered by a poor understanding and characterization of its pharmacokinetic/pharmacodynamic (PK/PD) relationships. Therefore, to better define these relationships, we performed in-depth analyses of the PK/PD relationships of native follistatin-315 (FST315).
Our data indicate that the intrinsic PK/PD properties of native FST315 are poorly suited for acting as a parentally administered biotherapeutic with broad systemic effects. Here, we leveraged protein engineering to modify the PK characteristics of the native molecule by fusing FST315 to a murine IgG(1) Fc and removing the intrinsic heparan sulfate-binding activity of follistatin. The engineered variant molecule had ~100- and ~1600-fold improvements in terminal half-life and exposure, respectively. In contrast to the native FST315, the variant showed a robust, dose-dependent pharmacological effect when administered subcutaneously on a weekly basis in mouse models of muscle atrophy and degeneration. These studies highlight the underappreciated and critical relationship between optimizing multiple physical and chemical properties of follistatin on its overall PK/PD profile. Moreover, our findings provide the first documented strategy toward the development of a follistatin therapeutic with potential use in patients affected with skeletal muscle diseases.
Muscle Nerve. 2009 Mar;39(3):283-96. doi: 10.1002/mus.21244.
Inhibition of myostatin with emphasis on follistatin as a therapy for muscle disease
1Center for Gene Therapy, Research Institute at Nationwide Children's Hospital, 700 Children's Drive, Columbus, Ohio 43205 USA.
In most cases, pharmacologic strategies to treat genetic muscle disorders and certain acquired disorders, such as sporadic inclusion body myositis, have produced modest clinical benefits. In these conditions, inhibition of the myostatin pathway represents an alternative strategy to improve functional outcomes. Preclinical data that support this approach clearly demonstrate the potential for blocking the myostatin pathway. Follistatin has emerged as a powerful antagonist of myostatin that can increase muscle mass and strength. Follistatin was first isolated from the ovary and is known to suppress follicle-stimulating hormone. This raises concerns for potential adverse effects on the hypothalamic-pituitary-gonadal axis and possible reproductive capabilities. In this review we demonstrate a strategy to bypass off-target effects using an alternatively spliced cDNA of follistatin (FS344) delivered by adeno-associated virus (AAV) to muscle. The transgene product is a peptide of 315 amino acids that is secreted from the muscle and circulates in the serum, thus avoiding cell-surface binding sites. Using this approach our translational studies show increased muscle size and strength in species ranging from mice to monkeys. Adverse effects are avoided, and no organ system pathology or change in reproductive capabilities has been seen. These findings provide the impetus to move toward gene therapy clinical trials with delivery of AAV-FS344 to increase size and function of muscle in patients with neuromuscular disease.
Zoolog Sci. 2009 May;26(5):315-20. doi: 10.2108/zsj.26.315.
Expression of myostatin and follistatin in Mdx mice, an animal model for muscular dystrophy
1Department of Anatomy, Tokyo Dental College, Chiba-City, Chiba, Japan.
Follistatin is a functional antagonist of several members of the TGF-beta family of secreted signaling factors, including myostatin, the most powerful inhibitor of muscle growth characterized to date. Myostatin inhibition offers a novel therapeutic strategy for muscular dystrophy by restoring skeletal muscle mass and suppressing the progression of muscle degeneration. To assess the potential benefits of follistatin in treating muscle degenerative diseases, we examined the expression of myostatin and follistatin in Mdx mice, a model for Duchenne muscular dystrophy, and in B10 mice as a control. Our results demonstrated a temporary and coincident expression of follistatin and myostatin in both mouse strains, but this expression was significantly higher in Mdx mice than in B10 mice. The maximum expression of follistatin and myostatin in the presence of restoring necrotic muscle was detected 4 weeks after birth in Mdx mice. Interestingly, during the stage of complete regeneration, the absence of myostatin and follistatin proteins and a marked decrease in the expression of both genes were observed 9 weeks after birth in both mouse strains. These findings suggest that follistatin not only blocks myostatin but also allows other activators to function in muscle development, emphasizing that follistatin could be a very potent molecule in combating muscle loss during dystrophies and muscle ageing, disuse, or denervation.
Eur J Clin Invest. 2008 Jul;38(7):531-8. doi: 10.1111/j.1365-2362.2008.01970.x.
Muscle myostatin signalling is enhanced in experimental cancer cachexia
1Department of Experimental Medicine and Oncology Università di Torino, Italy.
Myostatin belongs to the transforming growth factor-beta superfamily and negatively regulates skeletal muscle mass. Its deletion induces muscle overgrowth, while, on the contrary, its overexpression or systemic administration cause muscle atrophy. The present study was aimed at investigating whether muscle depletion as occurring in an experimental model of cancer cachexia, the rat bearing the Yoshida AH-130 hepatoma, is associated with modulations of myostatin signalling and whether the cytokine tumour necrosis factor-alpha may be relevant in this regard.
MATERIALS AND METHODS:
Protein levels of myostatin, follistatin (myostatin endogenous inhibitor) and the activin receptor type IIB have been evaluated in the gastrocnemius of tumour-bearing rats by Western blotting. Circulating myostatin and follistatin in tumour hosts were evaluated by immunoprecipitation, while the DNA-binding activity of the SMAD transcription factors was determined by electrophoretic-mobility shift assay.
In day 4 tumour hosts muscle myostatin levels were comparable to controls, yet follistatin was reduced, and SMAD DNA-binding activity was enhanced. At day 7, both myostatin and follistatin increased in tumour bearers, while SMAD DNA-binding activity was unchanged. To investigate whether tumour necrosis factor-alpha contributed to induce such changes, rats were administered pentoxifylline, an inhibitor of tumour necrosis factor-alpha synthesis that partially corrects muscle depletion in tumour-bearing rats. The drug reduced both myostatin expression and SMAD DNA-binding activity in day 4 tumour hosts and up-regulated follistatin at day 7.
These observations suggest that myostatin pathway should be regarded as a potential therapeutic target in cancer cachexia.
Acta Myol. 2008 Jul;27:14-8.
Myostatin inhibition by a follistatin-derived peptide ameliorates the pathophysiology of muscular dystrophy model mice
Division for Therapies against Intractable Diseases, Institute for Comprehensive Medical Science (ICMS), Fujita Health University, Toyoake, Aichi, Japan.
Gene-targeted therapies, such as adeno-associated viral vector (AAV)-mediated gene therapy and cell-mediated therapy using myogenic stem cells, are hopeful molecular strategies for muscular dystrophy. In addition, drug therapies based on the pathophysiology of muscular dystrophy patients are desirable. Multidisciplinary approaches to drug design would offer promising therapeutic strategies. Myostatin, a member of the transforming growth factor-beta superfamily, is predominantly produced by skeletal muscle and negatively regulates the growth and differentiation of cells of the skeletal muscle lineage. Myostatin inhibition would increase the skeletal muscle mass and prevent muscle degeneration, regardless of the type of muscular dystrophy. Myostatin inhibitors include myostatin antibodies, myostatin propeptide, follistatin and follistatin-related protein. Although follistatin possesses potent myostatin-inhibiting activity, it works as an efficient inhibitor of activins. Unlike myostatin, activins regulate the growth and differentiation of nearly all cell types, including cells of the gonads, pituitary gland and skeletal muscle. We have developed a myostatin-specific inhibitor derived from follistatin, designated FS I-I. Transgenic mice expressing this myostatin-inhibiting peptide under the control of a skeletal muscle-specific promoter showed increased skeletal muscle mass and strength. mdx mice were crossed with FS I-I transgenic mice and any improvement of the pathological signs was investigated. The resulting mdx/FS I-I mice exhibited increased skeletal muscle mass and reduced cell infiltration in muscles. Muscle strength was also recovered in mdx/FS I-I mice. Our data indicate that myostatin inhibition by this follistatin-derived peptide has therapeutic potential for muscular dystrophy.