Peripheral administration of brain-derived neurotrophic factor to Rett syndrome animal model: a possible approach for the treatment of Rett syndrome

Brain-Derived Neurotrophic Factor Secreting Human Mesenchymal Stem Cells Improve Outcomes in Rett Syndrome Mouse Models

Rett syndrome (RTT) is a severe X-linked dominant neurodevelopmental disorder caused by mutations in the methyl-CpG-binding protein 2 (MECP2) gene; MeCP2 regulates the expression of brain-derived neurotrophic factor (BDNF) and increasing BDNF levels ameliorates RTT symptoms. However, the clinical application of BDNF is limited, because of its short half-life and low penetrance across the blood-brain barrier. In this study, we generated BDNF-secreting mesenchymal stem cells (MSCs) from the human umbilical cord cells, using CRISPR-Cas9. We studied the effects of BDNF-MSCs in MECP2 knockout and MECP2-deficient mice. BDNF-MSCs upregulated the expression of BDNF, pAKT, and pERK1/2 and downregulated that of pp38, both in vitro and in vivo. In our in vivo experiments, BDNF-MSCs increased the body and brain weights in mice. BDNF-MSCs increased the neuronal cell numbers in the hippocampus, cortex, and striatum; in addition, they increased the number of synapses. BDNF-MSCs upregulated BDNF and the activity of BDNF downstream effectors, such as pAKT and pERK 1/2; this upregulation was persistent. In conclusion, BDNF-MSCs generated using CRISPR-Cas9 could be a therapeutic strategy for treating RTT.

FEASibility testing a randomized controlled trial of an exercise program to improve cognition for T2DM patients (the FEAST trial): A study protocol

While cognitive dysfunction is an important concern in persons with type 2 diabetes mellitus (T2DM), it has received little attention in the T2DM literature. Although it often remains unrecognized, cognitive dysfunction associated with T2DM can lead to severe consequences. Prior research studies have consistently shown that aerobic exercise enhances cognitive function among healthy subjects. However, very few studies have examined the effects of aerobic exercise on cognitive function in persons with T2DM. In addition, one important single-nucleotide polymorphism that influences cognition in humans is the brain-derived neurotrophic factor (BDNF) Val66Met variant. Despite strong evidence suggesting aerobic exercise has a beneficial effect on cognitive function, there is significant variability in individual response to exercise programs on cognitive outcomes among Val/Val versus Met carriers. However, the evidence on how the BDNF Val66Met variant influences cognitive outcomes following an aerobic exercise intervention among individuals with T2DM is currently lacking. Therefore, the purpose of this randomized controlled trial is to pilot-test a 3-month supervised exercise program to improve plasma BDNF levels and cognition, overall and according to genotypes of the BDNF Val66Met variant. A total of 81 patients with T2DM will be randomly assigned to either aerobic exercise group (n = 54) or attention control group (n = 27) for 3 months. Outcomes of interest include postintervention changes in plasma BDNF levels, fasting blood glucose, hemoglobin A1c, body mass index, executive function, memory, and processing speed. This study will provide further evidence on use of exercise as a non-pharmaceutical, low-cost intervention to improve cognition in this population.

Challenges of BDNF-based therapies: From common to rare diseases

Neurotrophins are a well-known family of neurotrophic factors that play an important role both in the central and peripheral nervous systems, where they modulate neuronal survival, development, function and plasticity. Brain-derived neurotrophic factor (BDNF) possesses diverse biological functions which are mediated by the activation of two main classes of receptors, the tropomyosin-related kinase (Trk) B and the p75 neurotrophin receptor (p75^NTR). The therapeutic potential of BDNF has drawn attention since dysregulation of its signalling cascades has been suggested to underlie the pathogenesis of both common and rare diseases. Multiple strategies targeting this neurotrophin have been tested; most have found obstacles that ultimately hampered their effectiveness. This review focuses on the involvement of BDNF and its receptors in the pathophysiology of Alzheimer's disease (AD), Amyotrophic Lateral Sclerosis (ALS) and Rett Syndrome (RTT). We describe the known mechanisms leading to the impairment of BDNF/TrkB signalling in these disorders. Such mechanistic insight highlights how BDNF signalling compromise can take various shapes, nearly disease-specific. Therefore, BDNF-based therapeutic strategies must be specifically tailored and are more likely to succeed if a combination of resources is employed.

The use of iPSC technology for modeling Autism Spectrum Disorders

Autism Spectrum Disorders (ASDs) are a group of neurodevelopmental disorders that influence social skills, involving communication, interaction, and behavior, usually with repetitive and restrictive manners. Due to the variety of genes involved in ASDs and several possible environmental factors influence, there is still no answer to what really causes syndromic and non-syndromic types of ASDs, usually affecting each individual in a unique way. However, we know that the mechanism underlying ASDs involves brain functioning. The human brain is a complex structure composed of close to 100 billion cells, which is a big challenge to study counting just with post mortem tissue investigation or genetic approaches. Therefore, human induced pluripotent stem cells (iPSC) technology has been used as a tool to produce viable cells for understanding a working brain. Taking advantage of patient-derived stem cells, researchers are now able to generate neurons, glial cells and brain organoids in vitro to model ASDs. In this review we report data from different studies showing how iPSCs have been a critical tool to study the different phenotypes of ASDs.

A Potential Life-Threatening Reaction to Glatiramer Acetate in Rett Syndrome

BACKGROUND

Rett syndrome is an X-linked dominant neurodevelopmental disorder manifesting with severe intellectual disability in females caused by various mutations in the MECP2 gene. Brain-derived neurotrophic factor (BDNF) is one of the main proteins regulated by the MECP2 protein; its overexpression in the MeCP2 mouse model partially corrects the Rett phenotype. Pharmacologic manipulations that lead to increased BDNF in individuals with Rett syndrome are expected to have a positive effect on the disorder. Glatiramer acetate, a well-known and safe multiple sclerosis immune modulator, increases BDNF levels in multiple sclerosis animal models and patients responding to treatment, as well as in Rett mouse models.

METHODS

Fourteen patients with mutation-proven Rett syndrome were recruited for a clinical trial with glatiramer acetate. Baseline data and follow-up data were collected during the trial, which had to be stopped because of a severe adverse event. Our objective is to describe this unexpected potentially life-threatening event in response to glatiramer in patients with Rett syndrome.

RESULTS

Four of 14 patients with Rett syndrome who were recruited and treated with daily injections of glatiramer acetate as part of an open-label clinical trial developed an exaggerated immediate postinjection response, which was experienced as life threatening in three of the patients, necessitating arrest of the trial.

CONCLUSION

Despite the known safety profile of glatiramer acetate in adult and pediatric patients with multiple sclerosis, its use in Rett syndrome should be cautiously reconsidered. The described severe adverse event can be related to these patients' primary autonomic nervous system dysfunction.

Antidiabetic Effect of Brain-Derived Neurotrophic Factor and Its Association with Inflammation in Type 2 Diabetes Mellitus

Brain-derived neurotrophic factor (BDNF) is a neurotrophin, which plays an important role in the central nervous system, and systemic or peripheral inflammatory conditions, such as acute coronary syndrome and type 2 diabetes mellitus (T2DM). BDNF is also expressed in several nonneuronal tissues, and platelets are the major source of peripheral BDNF. Here, we reviewed the potential role of BDNF in platelet reactivity in T2DM and its association with selected inflammatory and platelet activation mediators. Besides that, we focused on adipocytokines such as leptin, resistin, and adiponectin which are considered to take part in inflammation and both lipid and glucose metabolism in diabetic patients as previous studies showed the relation between adipocytokines and BDNF. We also reviewed the evidences of the antidiabetic effect of BDNF and the association with circulating inflammatory cytokines in T2DM.

Dysregulated brain immunity and neurotrophin signaling in Rett syndrome and autism spectrum disorders

Rett syndrome is a neurodevelopmental disorder, which occurs in about 1:15,000 females and presents with neurologic and communication defects. It is transmitted as an X-linked dominant linked to mutations of the methyl-CpG-binding protein (MeCP2), a gene transcription suppressor, but its definitive pathogenesis is unknown thus hindering development of effective treatments. Almost half of children with Rett syndrome also have behavioral symptoms consistent with those of autism spectrum disorders (ASDs). PubMed was searched (2005-2014) using the terms: allergy, atopy, brain, brain-derived neurotrophic factor (BDNF), corticotropin-releasing hormone (CRH), cytokines, gene mutations, inflammation, mast cells (MCs), microglia, mitochondria, neurotensin (NT), neurotrophins, seizures, stress, and treatment. There are a number of intriguing differences and similarities between Rett syndrome and ASDs. Rett syndrome occurs in females, while ASDs more often in males, and the former has neurologic disabilities unlike ASDs. There is evidence of dysregulated immune system early in life in both conditions. Lack of microglial phagocytosis and decreased levels of BDNF appear to distinguish Rett syndrome from ASDs, in which there is instead microglia activation and/or proliferation and possibly defective BDNF signaling. Moreover, brain mast cell (MC) activation and focal inflammation may be more prominent in ASDs than Rett syndrome. The flavonoid luteolin blocks microglia and MC activation, provides BDNF-like activity, reverses Rett phenotype in mouse models, and has a significant benefit in children with ASDs. Appropriate formulations of luteolin or other natural molecules may be useful in the treatment of Rett syndrome.

MeCP2 modulates the canonical Wnt pathway activation by targeting SFRP4 in rheumatoid arthritis fibroblast-like synoviocytes in rats

Rheumatoid arthritis (RA) is an autoimmune disease characterized by the rheumatoid factor and anti-citrullinated peptide antibody (ACPA) against common autoantigens that are widely expressed within and outside the joints. Many factors participate in the pathogenesis of RA, such as cytokine imbalance, Wnt pathway activation, matrix production, and osteoprotegerin on osteoclasts. Fibroblast-like synoviocytes (FLS) activation has an important role in RA pathogenesis. The methyl-CpG-binding protein (MeCP2) which promoted repressed chromatin structure was selectively detected in synovium of diseased articular in rats. Overexpression of this protein results in an up-regulation of global methylation levels and transcriptional suppression of specific genes. There were increased MeCP2 and decreased secreted frizzled-related protein 4 (SFRP4) in synovium as well as the FLS isolated from the synovium of RA rats. Knockdown of MeCP2 using siRNA technique enhanced SFRP4 expression in both mRNA and protein levels in FLS. These results indicated that epigenetic modification was involved in differential expression of SFRP4. To further explore the underlying molecular mechanisms, we hypothesized that the SFRP4 down-regulation in synovium was caused by DNA methylation. Treatment of FLS with DNA methylation inhibitor 5-Aza-2'-deoxycytidine (5-azadC) blocked the cell proliferation and increased the SFRP4 expression. Increased SFRP4 down-regulated the key gene β-catenin, the downstream effectors gene ccnd1 and fibronectin expression in canonical Wnt pathway at the same time. MeCP2 and DNA methylation may provide molecular mechanisms for canonical Wnt pathway activation in RA. Combination of 5-azadC and MeCP2 may be a promising treatment strategy for individuals with RA in which SFRP4 is inactivated.