Growth Differentiation Factor 11 Levels Research Articles

Targeted Approach to Distinguish and Determine Absolute Levels of GDF8 and GDF11 in Mouse Serum.

Growth differentiation factor 11 (GDF11) is a TGF-β superfamily circulating factor that regulates cardiomyocyte size in rodents, sharing 90% amino acid sequence identity in the active domains with myostatin (GDF8)-the major determinant of skeletal muscle mass. Conflicting data on age-related changes in circulating levels have been reported mainly due to the lack of specific detection methods. More recently, liquid chromatography tandem mass spectrometry (LC-MS/MS) based assay showed that the circulating levels of GDF11 do not change significantly throughout human lifespan, but GDF8 levels decrease with aging in men. Here a novel detection method is demonstrated based on parallel reaction monitoring LC-MS/MS assay combined with immunoprecipitation to reliably distinguish GDF11 and GDF8 as well as determine their endogenous levels in mouse serum. The data indicate that both GDF11 and GDF8 circulating levels significantly decline with aging in female mice.

Circulating Concentrations of GDF11 are Positively Associated with TSH Levels in Humans.

Growth differentiation factor 11 (GDF11) is a member of the transforming growth factor (TGF)-β superfamily which declines with age and has been proposed as an anti-aging factor with regenerative effects in skeletal muscle in mice. However, recent data in humans and mice are conflicting, casting doubts about its true functional actions. The aim of the present study was to analyze the potential involvement of GFD11 in energy homeostasis in particular in relation with thyroid hormones. Serum concentrations of GDF11 were measured by enzyme-linked immunosorbent assay (ELISA) in 287 subjects. A highly significant positive correlation was found between GDF11 and thyroid-stimulating hormone (TSH) concentrations (r = 0.40, p < 0.001). Neither resting energy expenditure (REE) nor REE per unit of fat-free mass (REE/FFM) were significantly correlated (p > 0.05 for both) with GDF11 levels. In a multiple linear regression analysis, the model that best predicted logGDF11 included logTSH, leptin, body mass index (BMI), age, and C-reactive protein (logCRP). This model explained 37% of the total variability of logGDF11 concentrations (p < 0.001), with only logTSH being a significant predictor of logGDF11. After segregating subjects by TSH levels, those within the low TSH group exhibited significantly decreased (p < 0.05) GDF11 concentrations as compared to the normal TSH group or the high TSH group. A significant correlation of GDF11 levels with logCRP (r = 0.19, p = 0.025) was found. GDF11 levels were not related to the presence of hypertension or cardiopathy. In conclusion, our results show that circulating concentrations of GDF11 are closely associated with TSH concentrations and reduced in subjects with low TSH levels. However, GDF11 is not related to the regulation of energy expenditure. Our data also suggest that GDF11 may be involved in the regulation of inflammation, without relation to cardiac function. Further research is needed to elucidate the role of GDF11 in metabolism and its potential involvement in thyroid pathophysiology.

1752-P: GDF11 Involved in Expressed MicroRNAs during GLP-1RA Inhibited Adipogenesis

Differentiation of bone marrow mesenchymal stem cells (BMSCs)is controlled by a vast array of mechanisms, with miRNAs-mRNAs regulation network identified widely recently. In this study, we aimed to specify the differentially expressed (DE) miRNAs after glucagon-like peptide-1 receptor agonist (GLP-1RA) administration during adipogenesis in BMSCs. MiRNAs extracted from three different groups, [the control group (C), the adipogenesis group (A), and the GLP-1RA administration group (GA)], were sent for high-throughput sequencing. We identified 5 DE miRNAs (miRNA-150-5p, miRNA-129-5p, miRNA-201-3p, miRNA-201-5p, and miRNA-214-5p) among groups. The expression of the 5 DE miRNAs were verified by the real-time RT-PCR analysis and consistent with the small-RNA sequencing data. Target genes were then predicted, and highly enriched GOs and KEGG pathway analyses indicated that they were involved in multiple biological processes concerning adipogenesis. Two of the target genes, growth differentiation factor 11 (GDF11) and cholecystokinin B receptor (CCKBR), were verified for functional study. Actually, the mRNA levels of GDF11, rather than CCKBR, was down-regulated by miRNA-150-5pand involved in GLP-1RA administration. Taken together, these results suggested for the first time that GDF11 was involved in differentially expressed microRNAs during GLP-1RA inhibited adipogenesis in primary BMSCs. Disclosure P. Xue: None. N. Wang: None. Z. Li: None. S. Li: None. L. Yukun: None. Funding Natural Science Foundation of Hebei Province (H2016206243); Department of Health of Hebei Province (361005)

Analysis of Cre-mediated genetic deletion of Gdf11 in cardiomyocytes of young mice.

Administration of active growth differentiation factor 11 (GDF11) to aged mice can reduce cardiac hypertrophy, and low serum levels of GDF11 measured together with the related protein, myostatin (also known as GDF8), predict future morbidity and mortality in coronary heart patients. Using mice with a loxP-flanked ("floxed") allele of Gdf11 and Myh6-driven expression of Cre recombinase to delete Gdf11 in cardiomyocytes, we tested the hypothesis that cardiac-specific Gdf11 deficiency might lead to cardiac hypertrophy in young adulthood. We observed that targeted deletion of Gdf11 in cardiomyocytes does not cause cardiac hypertrophy but rather leads to left ventricular dilation when compared with control mice carrying only the Myh6-cre or Gdf11-floxed alleles, suggesting a possible etiology for dilated cardiomyopathy. However, the mechanism underlying this finding remains unclear because of multiple confounding effects associated with the selected model. First, whole heart Gdf11 expression did not decrease in Myh6-cre; Gdf11-floxed mice, possibly because of upregulation of Gdf11 in noncardiomyocytes in the heart. Second, we observed Cre-associated toxicity, with lower body weights and increased global fibrosis, in Cre-only control male mice compared with flox-only controls, making it challenging to infer which changes in Myh6-cre;Gdf11-floxed mice were the result of Cre toxicity versus deletion of Gdf11. Third, we observed differential expression of cre mRNA in Cre-only controls compared with the cardiomyocyte-specific knockout mice, also making comparison between these two groups difficult. Thus, targeted Gdf11 deletion in cardiomyocytes may lead to left ventricular dilation without hypertrophy, but alternative animal models are necessary to understand the mechanism for these findings. NEW & NOTEWORTHY We observed that targeted deletion of growth differentiation factor 11 in cardiomyocytes does not cause cardiac hypertrophy but rather leads to left ventricular dilation compared with control mice carrying only the Myh6-cre or growth differentiation factor 11-floxed alleles. However, the mechanism underlying this finding remains unclear because of multiple confounding effects associated with the selected mouse model.

Circulating GDF11 levels are decreased with age but are unchanged with obesity and type 2 diabetes.

Growth differentiation factor 11 (GDF11) is a member of the transforming growth factor β (TGFβ) superfamily which declines with age and exerts anti-aging regenerative effects in skeletal muscle in mice. However, recent data in humans and mice are conflicting casting doubts about its true functional actions. The aim of the present study was to compare the circulating concentrations of GDF11 in individuals of different ages as well as body weight and glycemic status. Serum concentrations of GDF11 were measured by ELISA in 319 subjects. There was a significant increase in GDF11 concentrations in people in the 41-50 y group and a decline in the elder groups (61-70 and 71-80 y groups, P=0.008 for the comparison between all age groups). However, no significant correlation between fat-free mass index (FFMI), a formula used to estimate the amount of muscle mass in relation to height, and logGDF11 was observed (r=0.08, P=0.197). Moreover, no significant differences in circulating concentrations of GDF11 regarding obesity or glycemic status were found. Serum GDF11 concentrations in humans decrease in older ages being unaltered in obesity and T2D. Further studies should determine the exact pathophysiological role of GDF11 in aging.

GDF11 is increased in patients with aplastic anemia

ABSTRACTObject: To explore the critical role of growth differentiation factor 11 (GDF11) in the pathobiology of aplastic anemia (AA). Methods: We have examined the serum GDF11 levels for 79 AA patients and 30 healthy controls. A total of 79 AA patients, which included 29 new diagnosed (untreated) cases, 14 cases with no response, 21 partial remission (PR) cases and 15 complete remission (CR) cases after immunosuppressive therapy (IST). GDF11 serum levels were assessed by an enzyme-linked immunosorbent assay. GDF11 mRNA expression in peripheral blood mononuclear (PBMNC) was detected through real time polymerase chain reaction. The correlation between GDF11 expression and erythropoietic function was evaluated. Results: The serum GDF11 levels in untreated AA patients were higher than that of the control group. The serum GDF11 levels of PR patients or CR patients after IST was decreased, compared with untreated patients, but did not recover back to the normal levels. GDF11 levels had a negative correlation with hemoglobin (Hb) levels and reticulocyte counts in AA patients. GDF11 levels did not correlate with age, sex and severity of in AA patients. Conclusion: Serum GDF11 levels were increased and negatively correlated with Hb levels and reticulocyte counts in AA patients. This suggests an impaired GDF11 response contributing to anemia in AA patients.

Regenerative Capacity of Endogenous Factor: Growth Differentiation Factor 11; a New Approach of the Management of Age-Related Cardiovascular Events.

Aging is a complicated pathophysiological process accompanied by a wide array of biological adaptations. The physiological deterioration correlates with the reduced regenerative capacity of tissues. The rejuvenation of tissue regeneration in aging organisms has also been observed after heterochronic parabiosis. With this model, it has been shown that exposure to young blood can rejuvenate the regenerative capacity of peripheral tissues and brain in aged animals. An endogenous compound called growth differentiation factor 11 (GDF11) is a circulating negative regulator of cardiac hypertrophy, suggesting that raising GDF11 levels could potentially treat or prevent cardiac diseases. The protein GDF11 is found in humans as well as animals. The existence of endogenous regulators of regenerative capacity, such as GDF11, in peripheral tissues and brain has now been demonstrated. It will be important to investigate the mechanisms with therapeutic promise that induce the regenerative effects of GDF11 for a variety of age-related diseases.

GDF11 Decreases Pressure Overload-Induced Hypertrophy, but Can Cause Severe Cachexia and Premature Death.

Possible beneficial effects of GDF11 (growth differentiation factor 11) on the normal, diseased, and aging heart have been reported, including reversing aging-induced hypertrophy. These effects have not been well validated. High levels of GDF11 have also been shown to cause cardiac and skeletal muscle wasting. These controversies could be resolved if dose-dependent effects of GDF11 were defined in normal and aged animals as well as in pressure overload-induced pathological hypertrophy. To determine dose-dependent effects of GDF11 on normal hearts and those with pressure overload-induced cardiac hypertrophy. Twelve- to 13-week-old C57BL/6 mice underwent transverse aortic constriction (TAC) surgery. One-week post-TAC, these mice received rGDF11 (recombinant GDF11) at 1 of 3 doses: 0.5, 1.0, or 5.0 mg/kg for up to 14 days. Treatment with GDF11 increased plasma concentrations of GDF11 and p-SMAD2 in the heart. There were no significant differences in the peak pressure gradients across the aortic constriction between treatment groups at 1 week post-TAC. Two weeks of GDF11 treatment caused dose-dependent decreases in cardiac hypertrophy as measured by heart weight/tibia length ratio, myocyte cross-sectional area, and left ventricular mass. GDF11 improved cardiac pump function while preventing TAC-induced ventricular dilation and caused a dose-dependent decrease in interstitial fibrosis (in vivo), despite increasing markers of fibroblast activation and myofibroblast transdifferentiation (in vitro). Treatment with the highest dose (5.0 mg/kg) of GDF11 caused severe body weight loss, with significant decreases in both muscle and organ weights and death in both sham and TAC mice. Although GDF11 treatment can reduce pathological cardiac hypertrophy and associated fibrosis while improving cardiac pump function in pressure overload, high doses of GDF11 cause severe cachexia and death. Use of GDF11 as a therapy could have potentially devastating actions on the heart and other tissues.

Relationship between serum level of growth differentiation factors 8, 11 and bone mineral density in girls with anorexia nervosa.

Adolescents with anorexia nervosa (AN) have low body mass and low bone mineral density (BMD). Growth differentiation factor 8 (Myostatin, GDF8) and its homologue growth differentiation factor 11 (GDF11), members of the TGF-β super-family, play an important role in muscle regeneration and bone metabolism in healthy individuals. However, their association with BMD in AN is unknown. The present study was undertaken to investigate the relationship between GDF8, GDF11 and BMD in adolescent girls with AN. Serum GDF8, GDF11 and BMD were determined in 25 girls (12-16years old) with AN and 31 healthy girls (12-16years old). Growth differentiation factor 8 levels were lower in AN subjects. On the contrary, GDF11 levels were higher in AN subjects than controls. There was no relationship between GDF8 and BMD. A significant negative correlation between GDF11 and BMD was found. In multiple linear stepwise regression analysis, BMI, 25-hydroxyvitamin D, GDF11, or lean mass, but not fat mass and GDF8, were independent predictors of BMD in the AN and control groups separately. Growth differentiation factor 11 was independent predictor of BMD in girls with AN. It suggested that GDF11 exerts a negative effect on bone mass.

Relationship of muscle function to circulating myostatin, follistatin and GDF11 in older women and men

BackgroundMyostatin, its inhibitor follistatin, and growth/differentiation factor 11 (GDF11) have been proposed as factors that could potentially modify biological aging. The study aimed to test whether there is a relationship between these plasma circulating proteins and muscle strength, power and optimal shortening velocity (υopt) of older adults.MethodsThe cross-sectional study included 56 women and 45 men aged 60 years and older. Every participant underwent examination which included anthropometric and bioimpedance analysis measurements, functional and cognitive performance tests, muscle strength of upper and lower extremities, muscle power testing with two different methods and blood analyses.ResultsWomen had higher plasma levels of myostatin and GDF11 than men. Men had higher plasma level of follistatin than women. In women, plasma level of myostatin was negatively correlated with left handgrip strength and υopt. Follistatin was negatively correlated with maximum power output (Pmax), power relative to kg of body mass (Pmax∙kg− 1) (friction-loaded cycle ergometer) and power at 70% of the 1-repetition maximum (1RM) strength value (P70%) of leg press (Keiser pneumatic resistance training equipment), and positively correlated with the Timed Up & Go (TUG) test. GDF11 was negatively correlated with body mass, body mass index, waist circumference, fat mass and the percentage of body fat. In men, there were no significant correlations observed between circulating plasma proteins and muscle function measures.ConclusionsThe circulating plasma myostatin and follistatin are negatively associated with muscle function in older women. There is stronger relationship between these proteins and muscle power than muscle strength. GDF11 has a higher association with the body mass and composition than muscle function in older women.

Effect of GDF11 on proliferation and apoptosis of esophageal cancer cells

This study was aimed at investigating the effect of growth differentiation factor 11 (GDF11) on the proliferation and apoptosis of esophageal cancer cells. Serum levels of GDF11 in esophageal cancer patients were determined with ELISA kits, and the correlation between serum GDF11 and pathological features of esophageal cancer were determined. The effect of recombinant GDF11 on the growth of esophageal cancer cells was measured by CCK6 method. In order to investigate the effect of recombinant GDF11 on the proliferation and apoptosis of esophageal cancer cells, the expression of apoptosis-promoting protein Bax and proliferative-associated protein Bcl-2 in esophageal cancer cells were determined using western blot. Moreover, GDF11 was used to treat esophageal cancer cells, and its effect on proliferation and apoptosis was determined with MTT assay and flow cytometry, respectively. The serum content of GDF11 was much less in esophageal cancer patients than in the control group. Esophageal GDF II in cancer patients was correlated with cancer differentiation: the higher the degree of differentiation, the higher the content of GDF11. GDF11 inhibits proliferation and apoptosis of esophageal cancer cells.

Growth Differentiation Factor 11 Promotes Neurovascular Recovery After Stroke in Mice.

Background: Growth differentiation factor 11 (GDF11), a member of transforming growth factor-β (TGF-β) superfamily, was shown to rejuvenate cardiac and skeletal muscle function and to improve cerebral vasculature and neurogenesis in old mice. However, recent experimental data reported that raising GDF11 levels inhibited skeletal muscle regeneration and had no effect on cardiac hypertrophy. Our aim was to investigate the effects of GDF11 on brain repair during the recovery phase after stroke.Methods: Mice were subjected to distal middle cerebral artery occlusion, and recombinant GDF11 (rGDF11) was injected intraperitoneally once a day during days 7–13 after stroke. Neuronal precursor cells (NPCs) proliferation and angiogenesis were assayed at 14 days. Neuronal regeneration was assayed at 42 days. The beam-walking test and CatWalk were used to evaluate behavioral functions. Downstream pathways of GDF11 were also investigated.Results: GDF11 was upregulated in the ipsilateral peri-infarct cortex and subventricular zone (SVZ) at 14 days after stroke. Treatment with rGDF11 enhanced the number of newborn NPCs and endothelial cells, microvascular length and area, and brain capillary perfusion. Western blots showed that rGDF11 upregulated brain-derived neurotrophic factor (BDNF) and increased the levels of proangiogenic factor angiopoietin-2 (Ang-2) and phosphorylation of vascular endothelial growth factor receptor-2 (VEGFR-2). We also found that rGDF11 upregulated the transcription factors Smad2 and Smad3 phosphorylation, but these activations were blocked by a TGF-β receptor inhibitor SB431542. Moreover, rGDF11-induced angiogenic remodeling and NPCs proliferation were reversed by injection of SB431542, suggesting that GDF11 may exert its effect via the TGF-β/Smad2/3 signaling pathway. Finally, treating mice with rGDF11 resulted in a significant increase in neuronal regeneration and functional recovery.Conclusion: GDF11 promoted neurogenesis and angiogenesis and contributed to functional recovery after stroke in mice.

Reduced expression of growth differentiation factor 11 promoted the progression of chronic obstructive pulmonary disease by activating the AKT signaling pathway

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory lung disease, which is associated with significant mortality and costs. The molecular mechanisms underlying the roles of cigarette smoke (an accepted risk factor for COPD) and growth differentiation factor 11 (GDF11), which is reduced in patients with COPD, in the occurrence of COPD are unclear. The aim of the present study was to explore the function of GDF11 in the progression of COPD. Western blotting analysis was used to determine the expression levels of GDF11 in serum and primary lung mesenchymal cells from patients with COPD and the healthy people, and the effect of cigarette smoke extract (CSE) on the expression of AKT, p-AKT (Ser473), p-AKT (Thr308) and GDF11 was examined. The correlations between the expression level of GDF11 and the ratio of forced expiratory volume in one second (FEV1) and forced vital capacity (FVC), as well as GDF11 and p-AKT (Ser473 and Thr308) in vivo and in vitro were examined. GDF11 expression was decreased in COPD patients’ serum and cells when compared with that from the healthy people, and it was positively correlated with the FEV1/FVC ratio. Exposure to CSE reduced the expression of GDF11 but increased the expression of p-AKT (Ser473 and Thr308). Together, the results suggested that CSE promoted the progression of COPD by downregulating the expression of GDF11, which then activated the AKT signaling pathway. This study suggests that GDF11 may be a novel target for the diagnosis and treatment of COPD.

Modulation of GDF11 expression and synaptic plasticity by age and training.

The Growth Differentiation Factor 11 (GDF11) has been controversially involved in the aging/rejuvenation process. To clarify whether GDF11 is differently expressed during aging, we have evaluated GDF11 levels in skeletal muscles and hippocampi of young and old mice, sedentary or subjected to a 12-weeks triweekly training protocol. The results of real-time PCR and Western blot analyses indicate that skeletal muscles of sedentary old mice express higher levels of GDF11 compared to young animals (p < 0.05). Conversely, in hippocampi no significant differences of GDF11 expression are detected. Analysis of long-term potentiation, a synaptic plasticity phenomenon, reveals that population spikes in response to a tetanic stimulus are significantly higher in sedentary young mice than in old animals (p < 0.01). Training induces a significant improvement of long-term potentiation in both young and old animals (p < 0.05), an increase (p < 0.05) of skeletal muscle GDF11 levels in young mice and a reduction of GDF11 expression in hippocampi of old mice (p < 0.05). Overall, data suggest that GDF11 can be considered an aging biomarker for skeletal muscles. Moreover, physical exercise has a positive impact on long-term potentiation in both young and old mice, while it has variable effects on GDF11 expression depending on age and on the tissue analyzed.

Quantitation of circulating GDF-11 and β2-MG in aged patients with age-related impairment in cognitive function.

Growth differentiation factor 11 (GDF-11) has been implicated in reverse effects of ageing on the central nervous system of humans. β2-microglobulin (β2-MG) has been reported to negatively regulate cognition. However, there is a lot of controversy about the role of GDF-11 and β2-MG in ageing and cognitive regulation. To examine the involvement of GDF-11 and β2-MG in the ageing process and cognitive dysfunction, a total of 51 healthy subjects and 41 elderly patients with different degrees of age-related cognitive impairment participated in the study. We measured plasma GDF-11 and β2-MG levels using ELISA and immunoturbidimetry, respectively. The results were statistically analyzed to evaluate the associations between levels of GDF-11 and β2-MG, and ageing and cognitive impairments. Circulating GDF-11 levels did not decline with age or correlate with ageing in healthy Chinese males. We did not detect differences in circulating GDF-11 levels amongst the healthy advanced age and four cognitive impairment groups. β2-MG levels increased with age, but there was no significant difference between healthy elderly males and advanced age males. Increased levels of β2-MG were observed in the dementia group compared with the healthy advanced age group. Our results suggest that circulating GDF-11 may not exert a protective effect during the ageing process or on cognitive function, and β2-MG may play a role in ageing and cognitive impairment. However, it is possible that the relatively small sample size in the present study affected the quality of the statistical analysis, and future studies are needed to further validate our findings.

Exogenous GDF11 induces cardiac and skeletal muscle dysfunction and wasting.

Growth differentiation factor 11 (GDF11), a TGF-beta superfamily member, is highly homologous to myostatin and essential for embryonic patterning and organogenesis. Reports of GDF11 effects on adult tissues are conflicting, with some describing anti-aging and pro-regenerative activities on the heart and skeletal muscle while others opposite or no effects. Herein, we sought to determine the in vivo cardiac and skeletal muscle effects of excess GDF11. Mice were injected with GDF11 secreting cells, an identical model to that used to initially identify the in vivo effects of myostatin. GDF11 exposure in mice induced whole body wasting and profound loss of function in cardiac and skeletal muscle over a 14-day period. Loss of cardiac mass preceded skeletal muscle loss. Cardiac histologic and echocardiographic evaluation demonstrated loss of ventricular muscle wall thickness, decreased cardiomyocyte size, and decreased cardiac function 10days following initiation of GDF11 exposure. Changes in skeletal muscle after GDF11 exposure were manifest at day 13 and wereassociated with wasting, decreased fiber size, and reduced strength. Changes in cardiomyocytes and skeletal muscle fibers were associated with activation of SMAD2, the ubiquitin-proteasome pathway and autophagy. Thus,GDF11 over administration in vivo results in cardiac and skeletal muscle loss, dysfunction, and death. Here, serum levels of GDF11 by Western blotting were 1.5-fold increased over controls. Although GDF11 effects in vivo are likely dose, route, and duration dependent, its physiologic changes are similar to myostatin and other Activin receptors ligands. These data support that GDF11, like its other closely related TGF-beta family members, induces loss of cardiac and skeletal muscle mass and function.

Decrease in an anti-ageing factor, growth differentiation factor 11, in chronic obstructive pulmonary disease

RationaleCellular senescence is observed in the lungs of patients with COPD and may contribute to the disease pathogenesis. Growth differentiation factor 11 (GDF11) belongs to the transforming growth factor β...

Growth differentiation factor 11 (GDF11) - a promising anti-ageing factor - is highly concentrated in platelets.

Recent research suggests that growth differentiation factor 11 (GDF11) could reverse age-related diseases and that its blood concentration decreases with age. This poses plasma from young donors as a therapeutic GDF11 source to treat age-related diseases. In addition, the tissue source of circulating GDF11 remains unknown. We analysed GDF11 levels in paired samples of serum, plasma and platelet lysate (PL) from 23 volunteers. Plasma and PL were collected by plateletpheresis. Here, we show that GDF11 is highly concentrated in platelets and that the circulating levels reported in previous studies could be biased as a result of serum sample manipulation.

Transcutaneous auricular vagus nerve stimulation regulates expression of growth differentiation factor 11 and activin-like kinase 5 in cerebral ischemia/reperfusion rats

Growth differentiation factor 11 (GDF11), as a rejuvenation factor in heterochronic parabiosis, can increase proliferation of primary brain capillary endothelial cells (ECs). However, the angiogenic role of GDF11 in ischemia-induced brain injury is still unclear. There are no previous reports on the spatiotemporal expression of GDF11 in cerebral ischemia/reperfusion (I/R) rats. Our recent work has strongly suggested that transcutaneous auricular vagus nerve stimulation (ta-VNS) reduces infarct size and induces angiogenesis in focal cerebral I/R rats. This study focused on expression of GDF11 and activin-like kinase 5 (ALK5) and the effects of ta-VNS in a rat cerebral I/R model. For ta-VNS, electrical stimulation of the left cavum concha (1h duration) using percutaneous needles was initiated 30min after induction of ischemia. Expression of GDF11 was analyzed by enzyme-linked immunosorbent assay, immunohistochemistry, real-time polymerase chain reaction, and western blot 24h, 3d, and 7d after reperfusion. In addition, neurobehavioral function, EC proliferation, and expression of ALK5 in ECs in the peri-infarct cortex were measured. Results showed that levels of GDF11 were significantly elevated after cerebral I/R, both in plasma and the peri-infarct cerebral cortex. Interestingly, splenic GDF11 levels decreased after ischemia. ALK5 was expressed in ECs in the peri-infarct cerebral cortex where active vessel remodeling was noted. ta-VNS improved neurobehavioral recovery, upregulated cerebral GDF11 and downregulated splenic GDF11, indicating a brain-spleen communication during stroke. ta-VNS also increased expression of ALK5 in ECs and stimulated proliferation of ECs. These results suggest that, after cerebral ischemia, GDF11 redistributes and participates in angiogenesis as an angiogenic factor that acts at least in part through ALK5. GDF11/ALK5 may represent a new potential therapy target for stroke.

Serum Levels of Growth Differentiation Factor 11 Are Independently Associated with Low Hemoglobin Values in Hemodialysis Patients

Circulating levels of growth differentiation factor 11 (GDF11) have been shown to decrease with age in several mammalian species, and supplementation of GDF11 by heterochronic parabiosis or systemic administration reverses age-related organ damage. However, there is some controversy about the pathophysiological role of GDF11 in aging-associated organ damage. Since aging process is accelerated in uremia, we compared serum levels of GDF11 in hemodialysis (HD) patients with those in age-matched healthy controls, and then determined the independent clinical correlates of GDF11 in HD subjects. Sixty-two maintenance HD patients (34 male and 28 female; mean age, 52.6 years; mean duration of HD, 7.7 months) were enrolled in the present study. Twenty-nine age-matched subjects were used as a control. GDF11 was measured by a commercially available enzyme-linked immunosorbent assay kit. Serum GDF11 levels in HD patients were significantly higher than those in controls (9.4 ± 5.1 pg/mL vs. 7.3 ± 5.9 pg/mL). A statistical significance was demonstrated between GDF11 and hemoglobin (inversely). Multiple stepwise regression analysis revealed that hemoglobin (p < 0.001) was a sole independent correlate of GDF11 levels in HD patients (R2 = 0.168). Our present study suggests that kinetics and regulation of circulating GDF11 may differ between normal physiological aging process and accelerated pathological aging conditions, such as uremia. Given that GDF11 has been shown to inhibit erythroid maturation in mice, elevation of GDF11 levels may be involved in erythropoietin-resistant anemia in HD patients.