The neuroprotective and neurorestorative effects of growth differentiation factor 11 in cerebral ischemic injury

Progress in the relationship between GDF11 and depression

Annually, the frequency of morbidity in depression has increased progressively in response to life stressors, and there is an increasing trend toward younger morbidity. The pathogenesis of depression is complicated and includes factors such as genetic inheritance and variations in physiological functions induced by various environmental factors. Currently, drug therapy has wide adaptability in clinical practice and plays an important role in the treatment of patients with mild depression. However, the therapeutic effects of most antidepressants are typically not significant and are associated with considerable adverse effects and addiction. Therefore, it is imperative to identify the deeper mechanisms of depression and search for alternative drug targets. Growth differentiation factor 11 (GDF11) is described as an anti-ageing molecule that belongs to a member of the transforming growth factor β family. Additionally, the latest research findings suggested that GDF11 positively regulates neurogenesis and enhances neuronal activity, thereby attenuating depression-like behaviours. Although an increasing number of studies have focused on the multiple functions of GDF11 in skeletal dysplasia and carcinogenesis, its precise mechanism of action in depression remains unknown. Thus, in this review, we discuss the role of GDF11 and its mechanistic pathways in the pathogenesis of depression to develop novel therapies for depression.

Growth differentiation factor 11: A new hope for the treatment of cardiovascular diseases

Growth differentiation factor 11 (GDF11) is a member of the transforming growth factor-β superfamily that has garnered significant attention due to its anti-cardiac aging properties. Many studies have revealed that GDF11 plays an indispensable role in the onset of cardiovascular diseases (CVDs). Consequently, it has emerged as a potential target and novel therapeutic agent for CVD treatment. However, currently, no literature reviews comprehensively summarize the research on GDF11 in the context of CVDs. Therefore, herein, we comprehensively described GDF11's structure, function, and signaling in various tissues. Furthermore, we focused on the latest findings concerning its involvement in CVD development and its potential for clinical translation as a CVD treatment. We aim to provide a theoretical basis for the prospects and future research directions of the GDF11 application regarding CVDs.

Hydrogen sulfide antagonizes formaldehyde-induced ferroptosis via preventing ferritinophagy by upregulation of GDF11 in HT22 cells

Formaldehyde (FA) has neurotoxic characteristics and causes neurodegenerative disease. Our previous study demonstrated the neuroprotective effects of hydrogen sulfide (H₂S) on FA-induced neurotoxicity in HT22 cells. Emerging evidence have supported that ferroptosis is involved in FA-induced neurotoxicity. To understand the mechanism of the protection of H₂S against FA-induced neurotoxicity, this study explored the regulatory effect of H₂S on FA-induced ferroptosis and the underlying mechanisms. The researcher found that H₂S (100, 200, and 400μM, 30min) reverses the ferroptosis induced by FA (100μM, 24h) in HT22 cells (a cell line of mouse hippocampal neurons), including decreases in free iron, reactive oxygen species (ROS), 4-hydroxy-2-trans-nominal (4-HNE), and malondialdehyde (MDA) contents, as well as an increase in glutathione (GSH) content. H₂S (100, 200, and 400μM, 30min) also inhibited ferritinaphagy in FA-exposed HT22 cells, as evidenced by the downregulation of the ferritinophagy receptor nuclear receptor coactivator 4 (NCOA4) and microtubule-associated protein 1 light chain-3B (LC3B) as well as the upregulation of the main iron storage protein ferritin heavy chain 1 (FTH1) and p62. We also found that H₂S (100, 200, and 400μM, 30min) up-regulated the expression of growth differentiation factor-11 (GDF11) in FA-exposed HT22 cells. Furthermore, knockdown of GDF11 in HT22 cells cancelled the beneficial effects of H₂S in FA-induced ferroptosis and ferritinaphagy. These data indicated that the protective mechanism underlying H₂S-prevented neurotoxicity of FA is involved in alleviating FA-induced ferroptosis via inhibiting ferritinaphagy by upregulation of GDF11.

Plasma growth differentiation factor - 8 / Myostatin level as prognostic biomarker of patients with ischemic stroke and acute revascularization therapy. PARADISE study

BACKGROUND

Identifying biological markers of ischemic stroke (IS) is an important research approach to develop innovative therapeutic strategies. This study aimed to assess the association between plasma Growth Differentiation Factor-8 (GDF-8)/Myostatin levels and outcome of IS patients.

METHODS

Consecutive patients with acute IS treated with either intravenous thrombolysis and/or mechanical thrombectomy at Dijon University Hospital, France were prospectively included. Clinical variables were recorded, and plasma GDF-8 was collected just after the revascularization procedure. Primary endpoint was functional outcome at 3 months assessed by the modified Rankin Scale (mRS) score. Secondary endpoints included mRS scores at 6 and 12 months, and overall mortality over 1-year of follow-up.

RESULTS

Among the 173 included patients (median age: 76 years, Interquartile range (IQR): 66-85; 49% women), median plasma GDF-8 levels at admission were significantly lower in those with a poor outcome at 3 months defined as a mRS score > 2 (2073 (IQR: 1564-2757) pg/mL versus 1471 (1192-2241) pg/mL, p < 0.001). Lower GDF-8 levels at admission were associated with higher 3-months mRS score in multivariable ordinal logistic regression analysis (OR = 0.9995; 95% CI: 0.9991-0.9999, p = 0.011). The association was also observed with 6- and 12-month mRS scores. Although mortality was higher in patients with lower GDF-8 levels, the association was not significant in multivariable Cox analysis.

CONCLUSION

Lower plasma GDF-8 levels were associated with a poorer functional outcome in IS patients treated with acute revascularization therapy. Underlying pathophysiological mechanisms involving GDF-8 in post-stroke outcome remain to be elucidated.

Overexpressed ski efficiently promotes neurorestoration, increases neuronal regeneration, and reduces astrogliosis after traumatic brain injury

Traumatic brain injury (TBI) survivors suffer from long-term disability and neuropsychiatric sequelae due to irreparable brain tissue destruction. However, there are still few efficient therapies to promote neurorestoration in damaged brain tissue. This study aimed to investigate whether the pro-oncogenic gene ski can promote neurorestoration after TBI. We established a ski-overexpressing experimental TBI mouse model using adenovirus-mediated overexpression through immediate injection after injury. Hematoxylin-eosin staining, MRI-based 3D lesion volume reconstruction, neurobehavioral tests, and analyses of neuronal regeneration and astrogliosis were used to assess neurorestorative efficiency. The effects of ski overexpression on the proliferation of cultured immature neurons and astrocytes were evaluated using imaging flow cytometry. The Ski protein level increased in the perilesional region at 3 days post injury. ski overexpression further elevated Ski protein levels up to 14 days post injury. Lesion volume was attenuated by approximately 36-55% after ski overexpression, with better neurobehavioral recovery, more newborn immature and mature neurons, and less astrogliosis in the perilesional region. Imaging flow cytometry results showed that ski overexpression elevated the proliferation rate of immature neurons and reduced the proliferation rate of astrocytes. These results show that ski can be considered a novel neurorestoration-related gene that effectively promotes neurorestoration, facilitates neuronal regeneration, and reduces astrogliosis after TBI.

Multifaceted Benefits of GDF11 Treatment in Spinal Cord Injury: In Vitro and In Vivo Studies

Traumatic spinal cord injury (SCI) initiates a series of cellular and molecular events that include both primary and secondary injury cascades. This secondary cascade provides opportunities for the delivery of therapeutic intervention. Growth differentiation factor 11 (GDF11), a member of the transforming growth factor-β (TGF-β) superfamily, regulates various biological processes in mammals. The effects of GDF11 in the nervous system were not fully elucidated. Here, we perform extensive in vitro and in vivo studies to unravel the effects of GDF11 on spinal cord after injury. In vitro culture studies showed that GDF11 increased the survival of both neuronal and oligodendroglial cells but decreased microglial cells. In stressed cultures, GDF11 effectively inhibited LPS stimulation and also protected neurons from ischemic damage. Intravenous GDF11 administration to rat after eliciting SCI significantly improved hindlimb functional restoration of SCI rats. Reduced neuronal connectivity was evident at 6 weeks post-injury and these deficits were markedly attenuated by GDF11 treatment. Furthermore, SCI-associated oligodendroglial alteration were more preserved by GDF11 treatment. Taken together, GDF11 infusion via intravenous route to SCI rats is beneficial, facilitating its therapeutic application in the future.

Spermidine inhibits high glucose-induced endoplasmic reticulum stress in HT22 cells by upregulation of growth differentiation factor 11

Hyperglycemia-induced neuronal endoplasmic reticulum (ER) stress is particularly important for the pathogenesis of diabetic encephalopathy. Spermidine (Spd) has neuroprotection in several nervous system diseases. Our current study to explore the potential protective role of Spd in hyperglycemia-induced neuronal ER stress and the underlying mechanisms. HT22 cells were treated with high glucose (HG) to establish an in-vitro model of hyperglycemia toxicity. The HT22 cells' activity was tested by cell counting kit-8 assay. RNA interference technology was used to silence the expression of growth differentiation factor 11 (GDF11) in HT22 cells. The GDF11 expression levels of mRNA were assessed using reverse transcription-PCR (RT-PCR). Western blotting analysis was applied to evaluate the expressions of GRP78 and cleaved caspase-12. Spd markedly abolished HG-exerted decline in cell viability as well as upregulations of GRP78 and cleaved caspase-12 in HT22 cells, indicating the protection of Spd against HG-induced neurotoxicity and ER stress. Furthermore, we showed that Spd upregulated the expression of GDF11 in HG-exposed HT22 cells. While, silenced GDF11 expression by RNA interference reversed the protective effects of Spd on HG-elicited neurotoxicity and ER stress in HT22 cells. These results indicated that Spd prevents HG-induced neurotoxicity and ER stress through upregulation of GDF11. Our findings identify Spd as a potential treatment for diabetic encephalopathy as well as ER stress-related neurologic diseases.

In situ slow-release recombinant growth differentiation factor 11 exhibits therapeutic efficacy in ischemic stroke

Systemic growth differentiation factor 11 (GDF11) treatment improves the vasculature in the hippocampus and cortex in mice in recent studies. However, systemic application of recombinant GDF11 (rGDF11) cannot cross the brain blood barrier (BBB). Thus, large doses and long-term administration are required, while systemically applied high-dose rGDF11 is associated with deleterious effects, such as severe cachexia. This study tested whether in situ low dosage rGDF11 (1 μg/kg) protects the brain against ischemic stroke and it investigated the underlying mechanisms. Fibrin glue mixed with rGDF11 was applied to the surgical cortex for the slow release of rGDF11 in mice after permanent middle cerebral artery occlusion (MCAO). In situ rGDF11 improved cerebral infarction and sensorimotor function by upregulating Smad2/3 and downregulating FOXO3 expression. In situ rGDF11 was associated with reductions in protein and lipid oxidation, Wnt5a, iNOS and COX2 expression, at 24 h after injury. In situ rGDF11 protected hippocampal neurons and subventricular neural progenitor cells against MCAO injury, and increased newborn neurogenesis in the peri-infarct cortex. Systematic profiling and qPCR analysis revealed that Pax5, Sox3, Th, and Cdk5rap2, genes associated with neurogenesis, were increased by in situ rGDF11 treatment. In addition, greater numbers of newborn neurons in the peri-infarct cortex were observed with in situ rGDF11 than with systemic application. Our evidence indicates that in situ rGDF11 effectively decreases the extent of damage after ischemic stroke via antioxidative, anti-inflammatory and proneurogenic activities. We suggest that in situ slow-release rGDF11 with fibrin glue is a potential therapeutic approach against ischemic stroke.

GDF-11 Protects the Traumatically Injured Spinal Cord by Suppressing Pyroptosis and Necroptosis via TFE3-Mediated Autophagy Augmentation

Spinal cord injury (SCI) refers to a major worldwide cause of accidental death and disability. However, the complexity of the pathophysiological mechanism can result in less-effective clinical treatment. Growth differentiation factor 11 (GDF-11), an antiageing factor, was reported to affect the development of neurogenesis and exert a neuroprotective effect after cerebral ischaemic injury. The present work is aimed at investigating the influence of GDF-11 on functional recovery following SCI, in addition to the potential mechanisms involved. We employed a mouse model of spinal cord contusion injury and assessed functional outcomes via the Basso Mouse Scale and footprint analysis following SCI. Using western blot assays and immunofluorescence, we analysed the levels of pyroptosis, autophagy, necroptosis, and molecules related to the AMPK-TRPML1-calcineurin signalling pathway. The results showed that GDF-11 noticeably optimized function-related recovery, increased autophagy, inhibited pyroptosis, and alleviated necroptosis following SCI. Furthermore, the conducive influences exerted by GDF-11 were reversed with the application of 3-methyladenine (3MA), an autophagy suppressor, indicating that autophagy critically impacted the therapeutically related benefits of GDF-11 on recovery after SCI. In the mechanistic study described herein, GDF-11 stimulated autophagy improvement and subsequently inhibited pyroptosis and necroptosis, which were suggested to be mediated by TFE3; this effect resulted from the activity of TFE3 through the AMPK-TRPML1-calcineurin signalling cascade. Together, GDF-11 protects the injured spinal cord by suppressing pyroptosis and necroptosis via TFE3-mediated autophagy augmentation and is a potential agent for SCI therapy.

GDF11 expressed in the adult brain negatively regulates hippocampal neurogenesis

Growth differentiation factor 11 (GDF11) is a transforming factor-β superfamily member that functions as a negative regulator of neurogenesis during embryonic development. However, when recombinant GDF11 (rGDF11) is administered systemically in aged mice, it promotes neurogenesis, the opposite of its role during development. The goal of the present study was to reconcile this apparent discrepancy by performing the first detailed investigation into the expression of endogenous GDF11 in the adult brain and its effects on neurogenesis. Using quantitative histological analysis, we observed that Gdf11 is most highly expressed in adult neurogenic niches and non-neurogenic regions within the hippocampus, choroid plexus, thalamus, habenula, and cerebellum. To investigate the role of endogenous GDF11 during adult hippocampal neurogenesis, we generated a tamoxifen inducible mouse that allowed us to reduce GDF11 levels. Depletion of Gdf11 during adulthood increased proliferation of neural progenitors and decreased the number of newborn neurons in the hippocampus, suggesting that endogenous GDF11 remains a negative regulator of hippocampal neurogenesis in adult mice. These findings further support the idea that circulating systemic GDF11 and endogenously expressed GDF11 in the adult brain have different target cells or mechanisms of action. Our data describe a role for GDF11-dependent signaling in adult neurogenesis that has implications for how GDF11 may be used to treat CNS disease.

GDF11 alleviates secondary brain injury after intracerebral hemorrhage via attenuating mitochondrial dynamic abnormality and dysfunction

Intracerebral hemorrhage (ICH) is a serious public health problem with high rates of death and disability. The neuroprotective effect of Growth Differentiation Factor 11 (GDF11) in ICH has been initially proved by our previous study. Oxidative stress (OS) plays crucial roles in mediating subsequent damage of ICH. However, whether and how mitochondrial dynamic events and function participated in ICH pathophysiology, and how mitochondrial function and OS interreacted in the neuroprotective process of GDF11 in ICH remains unclarified. Based on the rat model of ICH and in vitro cell model, we demonstrated that GDF11 could alleviate ICH induced neurological deficits, brain edema, OS status, neuronal apoptosis and inflammatory reaction. In addition, mitochondrial functional and structural impairments were obviously restored by GDF11. Treatment with antioxidant protected against erythrocyte homogenate (EH) induced cell injury by restoring OS status and mitochondrial fusion fission imbalance, which was similar to the effect of GDF11 treatment. Further, inhibition of mitochondrial division with Mdivi-1 attenuated mitochondrial functional defects and neuronal damages. In conclusion, our results for the first time proposed that GDF11 protected the post-ICH secondary injury by suppressing the feedback loop between mitochondrial ROS production and mitochondrial dynamic alteration, resulting in attenuated mitochondrial function and amelioration of neural damage.

Similar sequences but dissimilar biological functions of GDF11 and myostatin

Growth differentiation factor 11 (GDF11) and myostatin (MSTN) are closely related TGFβ family members that are often believed to serve similar functions due to their high homology. However, genetic studies in animals provide clear evidence that they perform distinct roles. While the loss of Mstn leads to hypermuscularity, the deletion of Gdf11 results in abnormal skeletal patterning and organ development. The perinatal lethality of Gdf11-null mice, which contrasts with the long-term viability of Mstn-null mice, has led most research to focus on utilizing recombinant GDF11 proteins to investigate the postnatal functions of GDF11. However, the reported outcomes of the exogenous application of recombinant GDF11 proteins are controversial partly because of the different sources and qualities of recombinant GDF11 used and because recombinant GDF11 and MSTN proteins are nearly indistinguishable due to their similar structural and biochemical properties. Here, we analyze the similarities and differences between GDF11 and MSTN from an evolutionary point of view and summarize the current understanding of the biological processing, signaling, and physiological functions of GDF11 and MSTN. Finally, we discuss the potential use of recombinant GDF11 as a therapeutic option for a wide range of medical conditions and the possible adverse effects of GDF11 inhibition mediated by MSTN inhibitors.