Growth Differentiation Factor 15 Protein Research Articles

Mitochondrial dysfunction decreases cisplatin sensitivity in gastric cancer cells through upregulation of integrated stress response and mitokine GDF15.

Gastric neoplasm is a high-mortality cancer worldwide. Chemoresistance is the obstacle against gastric cancer treatment. Mitochondrial dysfunction has been observed to promote malignant progression. However, the underlying mechanism is still unclear. The mitokine growth differentiation factor 15 (GDF15) is a significant biomarker for mitochondrial disorder and is activated by the integrated stress response (ISR) pathway. The serum level of GDF15 was found to be correlated with the poor prognosis of gastric cancer patients. In this study, we found that high GDF15 protein expression might increase disease recurrence in adjuvant chemotherapy-treated gastric cancer patients. Moreover, treatment with mitochondrial inhibitors, especially oligomycin (a complex V inhibitor) and salubrinal (an ISR activator), respectively, was found to upregulate GDF15 and enhance cisplatin insensitivity of human gastric cancer cells. Mechanistically, it was found that the activating transcription factor 4-C/EBP homologous protein pathway has a crucial function in the heightened manifestation of GDF15. In addition, reactive oxygen species-activated general control nonderepressible 2 mediates the oligomycin-induced ISR, and upregulates GDF15. The GDF15-glial cell-derived neurotrophic factor family receptor a-like-ISR-cystine/glutamate transporter-enhanced glutathione production was found to be involved in cisplatin resistance. These results suggest that mitochondrial dysfunction might enhance cisplatin insensitivity through GDF15 upregulation, and targeting mitokine GDF15-ISR regulation might be a strategy against cisplatin resistance of gastric cancer.

Design and Synthesis of AMPK Activators and GDF15 Inducers.

Targeting growth differentiation factor 15 (GDF15) is a recent strategy for the treatment of obesity and type 2 diabetes mellitus (T2DM). Here, we designed, synthesized, and pharmacologically evaluated in vitro a novel series of AMPK activators to upregulate GDF15 levels. These compounds were structurally based on the (1-dibenzylamino-3-phenoxy)propan-2-ol structure of the orphan ubiquitin E3 ligase subunit protein Fbxo48 inhibitor, BC1618. This molecule showed a better potency than metformin, increasing GDF15 mRNA levels in human Huh-7 hepatic cells. Based on BC1618, structural modifications have been performed to create a collection of diversely substituted new molecules. Of the thirty-five new compounds evaluated, compound 21 showed a higher increase in GDF15 mRNA levels compared with BC1618. Metformin, BC1618, and compound 21 increased phosphorylated AMPK, but only 21 increased GDF15 protein levels. Overall, these findings indicate that 21 has a unique capacity to increase GDF15 protein levels in human hepatic cells compared with metformin and BC1618.

Hepatic glucuronyl C5-epimerase combats obesity by stabilising GDF15

Disturbed hepatic metabolism frequently results in excessive lipid accumulation in the adipose tissue. However, the specific role of the liver-adipose axis in maintaining lipid homeostasis, as well as the underlying mechanism, has not yet been fully elucidated. In this study, we investigated the role of hepatic glucuronyl C5-epimerase (Glce) in the progression of obesity. We determined the association between the expression of hepatic Glce and body mass index (BMI) in obese patients. Obesity models were established in hepatic Glce-knockout and wild-type mice fed a high-fat diet (HFD) to understand the effect of Glce on obesity development. The role of Glce in the progression of disrupted hepatokine secretion was examined via secretome analysis. Hepatic Glce expression was inversely correlated with BMI in obese patients. Moreover, Glce level was found to be decreased in the liver of a HFD murine model. Hepatic Glce deficiency led to impaired thermogenesis in adipose tissue and exacerbated HFD-induced obesity. Interestingly, decreased level of growth differentiation factor 15 (GDF15) was observed in the culture medium of Glce-knockout mouse hepatocytes. Treatment with recombinant GDF15 obstructed obesity progression derived from the absence of hepatic Glce, similar to the effect of Glce or its inactive mutant overexpressed both invitro and invivo. Furthermore, liver Glce deficiency led to diminished production and increased degradation of mature GDF15, resulting in reduced hepatic GDF15 secretion. Hepatic Glce deficiency facilitated obesity development, and decreased Glce expression further reduced hepatic secretion of GDF15, thereby perturbing lipid homeostasis invivo. Therefore, the novel Glce-GDF15 axis plays an important role in maintaining energy balance and may act as a potential target for combating obesity. Evidence suggests that GDF15 plays a key role in hepatic metabolism; however, the molecular mechanism for regulating its expression and secretion is largely unknown. Our work observes that hepatic Glce, as a key Golgi-localised epimerase, may work on the maturation and post-translational regulation of GDF15. Hepatic Glce deficiency reduces the production of mature GDF15 protein and facilitates its ubiquitination, resulting in the aggravation of obesity development. This study sheds light on the new function and mechanism of the Glce-GDF15 axis in lipid metabolism and provides a potential therapeutic target against obesity.

Association between growth differentiation factor 15 levels and gestational diabetes mellitus: A combined analysis.

Gestational diabetes mellitus (GDM) is a common glucose metabolism disease occurs in pregnancy that affects both maternal and neonatal health. Recently, increasing studies have attached importance to the relationship between growth differentiation factor 15 (GDF-15) and GDM, but the results were inconclusive. Therefore, we conducted a meta-analysis to examine the association between GDF-15 and GDM. A systematical search was performed in Gene Expression Omnibus (GEO), PubMed and Google Scholar till Oct 27, 2022. We first calculated the mean and standard deviation of GDF-15 expression levels from the included eligible datasets and articles. Then, a meta-analysis was conducted to depict the difference in GDF-15 mRNA or GDF-15 protein expression between case and control groups by using conservative random effect model. Moreover, the potential publication bias was checked with the aid of Begg's test and Egger's test. Finally, sensitivity analyses were performed by changing the inclusion criteria. In summary, 12 GEO datasets and 5 articles were enrolled in our study, including 789 GDM patients and 1202 non-GDM pregnant women. It was found that the expression levels of GDF-15 mRNA and GDF-15 protein in late pregnancy were significantly higher in GDM patients compared with non-GDM pregnant women, with the standard mean difference (SMD) and 95% confidence interval (95% CI) of 0.48 (0.14, 0.83) and 0.82 (0.32-1.33), respectively. Meanwhile, a slightly weakened association between GDF-15 protein levels and GDM was also observed in the middle pregnancy, with SMD (95% CI) of 0.53 (0.04-1.02). In all, our results suggested that the expression levels of GDF-15 were significantly higher in GDM patients compared with non-GDM pregnant women, especially in the late pregnancy.

Role of GDF-15 as an Immunohistochemical Marker in Follicular Neoplasms and Lesions of Thyroid

Introduction: A pre-therapeutic distinction between benign and malignant thyroid nodules is critical for deciding the therapeutic strategy, wherein fine-needle aspiration cytology plays a major role. However, there are grey-zone categories in the Bethesda system for reporting thyroid cytopathology, which is currently, the universally accepted pattern for reporting thyroid FNAC. Several immunomarkers studied in these ‘indeterminate’ lesions have proven to be of limited value. Recent molecular studies have shown the growth differentiation factor-15 (GDF-15) gene to be a promising marker in various malignancies; though, there is sparse literature regarding its use as a surrogate immunohistochemical marker, especially in thyroid neoplasms. The present (pilot) study explores its possible utility in the pre-therapeutic distinction of follicular-patterned lesions and neoplasms of the thyroid by testing it initially on histopathologic sections. Objective: To assess the utility of GDF-15 as an immunohistochemical marker in distinguishing common follicular-patterned thyroid neoplasms and lesions. Materials and Methods: GDF-15 immunohistochemistry was performed on 75 surgical specimens of thyroid lesions, comprising 19 adenomatous nodules or follicular hyperplasias, 10 nodular goitres, 17 follicular thyroid adenomas, 8 follicular thyroid carcinomas, 12 follicular variant of papillary thyroid carcinomas, and 9 conventional papillary thyroid carcinomas. All these cases were histologically proven, and their immunohistochemical interpretation was performed using the immunoreactive scoring system. Pearson’s analysis was performed for the immunohistochemical correlation among the study groups. Results: The findings were inconsistent; 16 follicular-patterned malignancies (5 follicular carcinomas and 11 cases of follicular variant of papillary carcinoma) and seven conventional papillary thyroid carcinomas revealed both cytoplasmic and membranous expression of GDF-15. All benign lesions were negative except one follicular adenoma and three follicular hyperplasias, which exhibited patchy or focal GDF-15 positivity. However, three follicular carcinomas, one follicular variant of papillary carcinoma, and two conventional papillary carcinomas were found to be GDF-15-negative. Conclusion: Though there is a literature backup supporting the use of GDF-15 gene analysis in differentiating various follicular-patterned neoplasms, the GDF-15 protein, as an immunohistochemical marker failed to distinguish not only between benign and malignant follicular-patterned neoplasms but also between follicular carcinoma and follicular variant of papillary carcinoma.

Growth differentiation factor 15 is required for triple-negative breast cancer cell growth and chemoresistance.

Growth differentiation factor 15 (GDF15) is a pleiotropic cytokine, which is involved in the cellular stress response following acute damage. However, the functional role of GDF15 in triple-negative breast cancer (TNBC) has not been fully elucidated. ELISA, Western blot, and PCR assays as well as bioinformatics analyses were conducted to observe the expression of GDF15. Cell Counting Kit-8, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and crystal violet staining assays were conducted to evaluate paclitaxel resistance and cell viability. Cell apoptosis was analyzed by Western blotting. Murine xenograft model assay was employed to evaluate tumor growth in vivo . Our data indicate that GDF15 is markedly elevated in paclitaxel-resistant TNBC cells, which is significantly associated with unfavorable prognosis. Silencing of GDF15 robustly inhibits the proliferation of tumor cells and increases their sensitivity to paclitaxel in vitro and in vivo , whereas the treatment of purified GDF15 protein confers breast cancer cells with chemoresistance ability. Moreover, GDF15 activates protein kinase B (AKT) /mammalian target of rapamycin (mTOR) signaling, inhibition of AKT or mTOR reverses the prosurvival effect of GDF15 and enhances the antitumor efficacy of paclitaxel in TNBC cells. Altogether, our study uncovers the role of GDF15 in tumor growth and paclitaxel resistance, implicating a potential therapeutic target for TNBC.

Atrial fibrillation in patients with obstructive sleep apnea and metabolic syndrome: the role of cytokines in the development of left atrial myocardial fibrosis

Objective. To determine the blood concentrations of biomarkers of fibrosis and inflammation in patients with metabolic syndrome (MS), atrial fibrillation (AF) and obstructive sleep apnea (OSA) and to establish their role in the formation of left atrial myocardial fibrosis. Design and methods. A cross-sectional case-control study included 286 patients aged 35 to 65 years: 78 patients with MS(+)/AF(+)/OSA(+), 79 patients with MS(+) / AF(+)/OSA(-), 73 patients with MS(+)/AF(-)/OSA(+) and 56 patients with MS(+)/AF(-)/OSA(-). Patients with AF and MS (n = 71) were assessed for the severity of left atrial myocardial fibrosis with electroanatomical mapping. Results. It was found that the concentration of profibrogenic biomarkers circulating in the blood of patients with MS(+)/AF(+)/OSA(+) is higher than in patients with MS(+)/AF(-)/OSA(+): galectin-3 (13,4 (8,5-17,6) and 8,4 (5,1-11,6) pg/ml, p < 0,0001), growth differentiation factor-15 (GDF-15) (1648,3 (775,32568,1) and 856,0 (622,5-1956,4) pg/ml, p < 0,0001), N-terminal peptide of type III procollagen (PIIINP) (95,6 (78,6-120,4) and 50,6 (38,9-68,3) ng/ml, p < 0,0001), N-terminal peptide of type I procollagen (PINP) (3459,4 (2167,1-4112,1) and 2355,3 (1925,0-3382,1) pg/ml, p < 0,0001). In the examined cohort of patients with OSA, positive correlations were found between galectin-3 and cardiotrophin-1 (r = 0,410, p = 0,00002), galectin-3 and GDF-15 (r = 0,430, p = 0,0003), galectin-3 and PIIINP (r = 0,451, p = 0,0001). Correlation analysis showed a strong positive relationship between the apnea/hypopnea index (AHI) and blood concentrations of GDF-15 (r = 0,661, p < 0,00001), galectin-3 (r = 0,519, p < 0,00001), interleukin 6 (r = 0,310, p = 0,0001) and C-reactive protein (CRP) (r = 0,361, p = 0,002). Negative correlations of the average level of SpO2 with CRP (r = -0,354, p = 0,001), galectin-3 (r = -0,451, p < 0,00001), GDF-15 (r = -0,637, p < 0,00001) were found. In patients with AF and OSA, fibrosis was more severe than in patients with AF without OSA (28,6 (23,6-36,6) and 13,5 (9,9-23,6) %, p = 0,0002). AHI positively correlated with the severity of fibrosis (r = 0,708, p < 0,00001). The patients with AF and OSA showed the strongest positive relationship between the severity of fibrosis and PINP (r = 0,572, p < 0,0001; в = 0,511, p < 0,0001) and galectin-3 (r = 0,449, p = 0,0009; в = 0,807, p < 0,0001). Conclusions. An increase in the concentration of fibrosis biomarkers in the blood is associated with an increase in the severity of left atrial myocardial fibrosis and probably has a pathogenetic role in increasing the risk of AF in patients with MS and OSA.

374-P: Identifying the Role and Mechanism by Which GDF15 Enhances the Counterregulatory Response to Hypoglycemia

Severe hypoglycemia is the leading acute mortality risk in patients with diabetes. The counterregulatory gluconeogenic and glycogenolytic response to hypoglycemia is the primary adaptive mechanism to enable survival. To better understand the hormonal response that orchestrates hypoglycemia counterregulation, we employed the insulin tolerance test (ITT) and hyperinsulinemic-hypoglycemic clamp to mimic the two common settings in which hypoglycemia can occur in patients: postprandial insulin overdose and elevated basal insulin infusion, respectively. We found that Growth Differentiation Factor 15 (GDF15) can be induced (33.5±2.1 vs. 172.4±29.2 pg/ml, P<0.in ITT and 46.2±11.6 vs. 2865±547.3 pg/ml, P<0.0in the clamp) . GDF15 mRNA and protein are upregulated in kidney, and the GDF15 tdTomato reporter mouse demonstrates the expression of GDF15 in the S3 segment of the proximal tubule. GDF15 increases hepatic gluconeogenesis (26.1±2.2 vs. 33.5±1.6 mg/kg/min, P<0.05) by increasing intrahepatic lipolysis in a beta-adrenergic receptor-2 (Adrb2) -dependent manner. To investigate the role of GDF15 counterregulation in diabetes, we utilized a streptozotocin (STZ) -induced type 1 diabetes (T1D) model. Mice with T1D exhibit impaired GDF15 production in an ITT. Additionally, we found that recurrent hypoglycemia impairs endogenous glucose production during hypoglycemia in mice (27.5±4 vs. 10.5±1.3 mg/kg/min, P<0.01) , which may result from lower GDF15 production (1372±248.2 vs. 648.5±71.3 pg/ml, P<0.05) . In humans, hypoglycemic clamps in healthy volunteers can induce GDF15 production (p=0.01) , although this induction was absent in patients with T1D. Conclusion: These data show the kidney can produce GDF15 in response to hypoglycemia, thereby increasing hepatic gluconeogenesis to enable survival. However, T1D patients are unable to initiate a functional GDF15 signaling pathway resulting in an impaired glucose counterregulatory response to hypoglycemia. Disclosure Z.Li: None. C.Zhang: None. R.Chang: None. J.J.Hwang: None. A.Wang: Research Support; NGM Biopharmaceuticals. R.J.Perry: None. X.Zhang: None. W.Zhu: None. Q.Xu: None. C.Yu: None. B.G.Costa lima: None. X.Li: None. K.Israni-winger: None. A.Nasiri: None. Funding National Institutes of Health (P30 DK045735) National Institutes of Health (R37 CA258271-01A1)

Effect of miR-488 on Colon Cancer Biology and Clinical Applications.

Objective To explore the expression levels of miR-488, miR-29c-3p, and growth differentiation factor 15 (GDF15) in colon cancer tissue and analyze their relationship with clinicopathological features in patients with colon cancer. Methods The study was conducted from November 2012 to November 2020. A total of 200 patients with colon cancer were treated in our hospital during this period. During the operation, the colon cancer tissues and the adjacent tissues whose distance from the cancer tissues were more than 5 cm were collected, and the expression levels of miR-488, miR-29c-3p, and GDF15 mRNA in colon cancer tissues were detected by qRT-PCR (real-time fluorescence quantitative). The relationship between them and the clinicopathological features and prognosis of patients with colon cancer were analyzed and discussed. Results The level of miR-488 in colon cancer tissues was lower than that in adjacent tissues, but the levels of miR-29c-3p and GDF15 mRNA in colon cancer tissues were higher than those in adjacent tissues (P < 0.05). Compared with paracancerous tissues, the expression rates of miR-29c-3p and GDF15 protein were higher in colon cancer tissues (P < 0.05). There was no difference in age, sex, tumor location, and tumor diameter between high expression of miR-488 group and low expression of miR-488 group (P > 0.05). The degree of differentiation, depth of invasion, TNM stage, lymph node metastasis, and other factors have a direct impact on the level of miR-488 and the expression of miR-29c-3p (P < 0.05). The depth of invasion, TNM stage, and lymph node metastasis could affect the expression of GDF15 in patients with colon cancer (P < 0.05). Conclusion miR-488, miR-29c-3p, and GDF15 in colon cancer tissue are related to the clinicopathological features of patients in varying degrees and may become markers after early warning of colon cancer, which can provide effective guidance for clinical diagnosis and treatment.

GDF-15 in tumor-derived exosomes promotes muscle atrophy via Bcl-2/caspase-3 pathway

Tumor-derived exosomes are emerging mediators of cancer cachexia, a kind of multifactorial syndrome characterized by serious loss of skeletal muscle mass and function. Our previous study had showed that microRNAs in exosomes of C26 colon tumor cells were involved in induction of muscle atrophy. Here, we focus on studying proteins in tumor-derived exosomes which might also contribute to the development of cancer cachexia. Results of comparing the protein profiles of cachexic C26 exosomes and non-cachexic MC38 exosomes suggested that growth differentiation factor 15 (GDF-15) was rich in C26 exosomes. Western blotting analysis confirmed the higher levels of GDF-15 in C26 cells and C26 exosomes, compared with that of MC38 cells. Results of animal study also showed that GDF-15 was rich in tumor tissues, serum exosomes, and gastrocnemius (GA) muscle tissues of C26 tumor-bearing mice. GDF-15 protein could directly induce muscle atrophy of cultured C2C12 myotubes via regulating Bcl-2/caspase-3 pathways. What’s more, overexpression of GDF-15 in MC38 cells could increase the potency of MC38 conditioned medium or exosomes in inducing muscle atrophy. Knockdown of GDF-15 in C26 cells decreased the potency of C26 conditioned medium or exosomes in inducing muscle atrophy. These results suggested that GDF-15 in tumor-derived exosomes could contribute to induction of muscle atrophy and also supported the possibility of targeting GDF-15 in treatment of cancer cachexia.

Abstract P330: Growth Differentiation Factor 15 Causes Cardiac Cachexia In Heart Failure

Background: Cachexia is wasting of normal body tissue and occurs in chronic medical diseases. It is a common complication of heart failure (HF) that is associated with very high mortality. Growth differentiation factor 15 (GDF15) regulates food intake and can cause cancer cachexia. GDF15 is a sensitive biomarker in humans, though its biologic function in HF is unknown. This study investigated the role of GDF15 in HF. Methods: We utilized a genetic mouse model of dilated cardiomyopathy (DCM) caused by a mutation in the phospholamban gene (PLN R9C ). PLN R9C mice have dysregulated cardiac calcium handling (a common feature of nearly all forms of HF) and develop progressive DCM that leads to HF and premature death. Q-PCR and ELISA were performed to assess expression, tissue distribution and circulating levels of GDF15 in PLN R9C and age-matched wild type (WT) mice. A double transgenic mouse was created by crossing our DCM model with a constitutive Gdf15 knock-out (KO). Using this novel model, we quantified food intake, and assessed fat and lean tissue mass by tissue weight at necropsy and by dual-energy X-ray absorptiometry (DXA). Cardiac function was assessed using echocardiography, and histochemistry performed to quantify cardiac fibrosis. Survival was assessed by Kaplan-Meier. Results: GDF15 mRNA (43-fold; p&lt;0.01) and protein (54-fold; p&lt;0.01) were increased in LV tissue, and circulating GDF15 was elevated (8.3-fold; p=0.03) in PLN R9C mice. Gdf15 was expressed at low levels and was not increased in other organs in PLN R9C mice. PLN R9C mice developed cachexia (reduced fat and lean mass by tissue weight, reduced fat mass by DXA vs. WT; p&lt;0.01 for all) and consumed less food (p&lt;0.01 vs. WT). Gdf15 KO in PLN R9C preserved fat and lean tissue mass and resulted in higher food intake (p≤0.01 for all). Gdf15 KO had no effect on cardiac structure or function by echocardiography and PLN R9C / Gdf15 KO mice displayed only a small reduction in cardiac fibrosis relative to PLN R9C mice (3%; p&lt;0.01). Despite this, Gdf15 KO prolonged survival in PLN R9C (29±3 vs. 25±3 weeks; p&lt;0.01). Conclusions: GDF15 is a novel cardiac hormone produced in HF that triggers anorexia and cachexia in HF by an extra-cardiac mechanism.

Chronic peripheral ghrelin injection exerts antifibrotic effects by increasing growth differentiation factor 15 in rat hearts with myocardial fibrosis induced by isoproterenol.

This study aimed to investigate the anti-fibrotic effects of ghrelin in isoproterenol (ISO)-induced myocardial fibrosis and the underlying mechanism. Sprague-Dawley rats were randomized to control, ISO, and ISO + ghrelin groups. ISO (2 mg/kg per day, subcutaneous) or vehicle was administered once daily for 7 days, then ghrelin (100 microg/kg per day, subcutaneous) was administered once daily for the next 3 weeks. Ghrelin treatment greatly improved the cardiac function of ISO-treated rats. Ghrelin also decreased plasma brain natriuretic peptide level and ratios of heart weight to body weight and left ventricular weight to body weight. Ghrelin significantly reduced myocardial collagen area and hydroxyproline content, accompanied by decreased mRNA levels of collagen type I and III. Furthermore, ghrelin increased plasma level of growth differentiation factor 15 (GDF15) and GDF15 mRNA and protein levels in heart tissues, which were significantly decreased with ISO alone. The phosphorylation of Akt at Ser473 and GSK-3beta at Ser9 was decreased with ISO, and ghrelin significantly reversed the downregulation of p-Akt and p-GSK-3beta. Mediated by GDF15, ghrelin could attenuate ISO-induced myocardial fibrosis via Akt-GSK-3beta signaling.

Serum GDF15, a Promising Biomarker in Obese Patients Undergoing Heart Surgery.

Background: Obesity is a risk factor that negatively impacts outcomes in patients undergoing heart surgery by mechanisms that are not well-defined nor predicated on BMI alone. This knowledge gap has fuelled a search for biomarkers associated with cardiovascular diseases that could provide clinical insight to surgeons. One such biomarker is growth differentiation factor15(GDF15), associated with inflammation, metabolism, and heart failure outcomes but not yet examined in the context of obesity and cardiac surgery outcomes.Methods: Patients undergoing open-heart surgery were consented and enrolled for blood and tissue (atria) sampling at the time of surgery. Biomarker analysis was carried out using ELISA and western blot/qPCR, respectively. Biomarker screening was classified by inflammation(NLR, GDF15, Galectin3, ST2, TNFR2), heart failure(HF)/remodeling(NT-proBNP) and metabolism(glycemia, lipid profile). Patients were categorized based on BMI: obese group (BMI ≥30.0) and non-obese group(BMI 20.0–29.9). Subsequent stratification of GDF15 high patients was conservatively set as being in the 75th percentile.Results: A total of 80 patients undergoing any open-heart surgical interventions were included in the study. Obese (mean BMI = 35.8, n = 38) and non-obese (mean BMI = 25.7, n = 42) groups had no significant differences in age, sex, or co-morbidities. Compared to other biomarkers, plasma GDF15 (mean 1,736 vs. 1,207 ng/l, p < 0.001) was significantly higher in obese patients compared to non-obese. Plasma GDF15 also displayed a significant linear correlation with BMI (R2 = 0.097; p = 0.0049). Atria tissue was shown to be a significant source of GDF15 protein and tissue levels significantly correlated with plasma GDF15 (R2 = 0.4, p = 0.0004). Obesity was not associated with early/late mortality at median follow-up >2years. However, patients with high GDF15 (>1,580 ng/l) had reduced survival (65%) compared to the remaining patients with lower GDF15 levels (95%) by Kaplan Meier Analysis (median >2 years; p = 0.007).Conclusions: Circulating GDF15 is a salient biomarker likely sourced from heart tissue that appears to predict higher risk obese patients for adverse outcomes. More importantly, elevated GDF15 accounted for more sensitive outcome association than BMI at 2 years post-cardiac surgery, suggesting it heralds links to pathogenicity and should be actively studied prospectively and dynamically in a post-operative follow-up.Trial number: NCT03248921.

50-OR: Beta Cell GDF15 Contributes to Diabetic Stress-Induced Beta-Cell Loss

Endoplasmic reticulum (ER) stress has been shown to play an important role in beta cell loss in diabetes. However, the factors involved in this process are still not fully understood. Growth differentiation factor 15 (GDF15), a member of the transforming growth factor beta (TGFβ) family, is a stress response gene and is involved in various diseases. GDF15 is expressed in adult human beta cells; however, its role in beta cells and diabetes had not been elucidated. Interestingly, we now have identified GDF15 as a key factor involved in ER stress-induced beta cell loss. We found that GDF15 mRNA, protein levels and promoter activity were significantly induced by ER stress in INS-1 cells, Akita beta cells, and primary human islets and we identified the transcription factor involved. Moreover, we discovered that overexpression of GDF15 exacerbated, while knockdown of GDF15 inhibited ER stress-induced beta cell apoptosis, at least in part by regulating the pro-apoptotic factor CHOP. Most importantly, we found that GDF15 knockout mice were protected from STZ-induced diabetes, maintained insulin producing beta cells and exhibited improved serum insulin levels. Taken together, our findings suggest that GDF15 plays an important role in ER stress-induced beta cell death and that inhibition of GDF15 may represent a novel strategy to reduce beta cell loss and treat diabetes. Disclosure G. Xu: None. S. Jo: None. J. Chen: None. T. Grayson: None. A. Shalev: None.

The myokine GDF-15 is a potential biomarker for myositis and associates with the protein aggregates of sporadic inclusion body myositis

BackgroundThe cytokine growth differentiation factor-15 (GDF-15) has been associated with inflammatory and mitochondrial disease, warranting exploration of its expression in myositis patients. MethodsGDF-15 protein levels are evaluated in 35 idiopathic inflammatory myopathy (IIM) serum samples using enzyme-linked immunosorbent assays, comparing with levels in samples from healthy individuals and from patients with genetically confirmed hereditary muscular dystrophies and mitochondrial disorders. Muscle tissue expression of GDF-15 protein is evaluated using immunofluorescent staining and Western blotting. ResultsGDF-15 protein levels are significantly higher in IIM sera (625 ± 358 pg/ml) than in that of healthy controls (326 ± 204 pg/ml, p = 0.01). Western blotting confirms increased GDF-15 protein levels in IIM muscle. In skeletal muscle tissue of IIM patients, GDF-15 localizes mostly to small regenerating or denervated muscle fibres. In patients diagnosed with sporadic inclusion body myositis, GDF-15 co-localizes with the characteristic protein aggregates within affected muscle fibres. ConclusionsWe describe for the first time that GDF-15 is a myokine upregulated in myositis and present the cytokine as a potential diagnostic serum biomarker.

GDF15 induced by compressive force contributes to osteoclast differentiation in human periodontal ligament cells

Orthodontic tooth movement (OTM) is initiated by mechanical force and featured as alveolar bone remodeling. Periodontal ligament cells (PDLCs) are one of the major cell components in periodontium and responsible for the signal transduction during OTM. Up to now, the mechanical stress-induced genetic alteration and mechanotransduction mechanisms in PDLCs still remain not fully understood. In this study, we identified a novel compressive force responsive gene, Growth differentiation factor 15 (GDF15), whose expression transcriptionally increased in human periodontal ligament cells (PDLCs) after exposure to the static compressive force in vitro. Functional analyses proved that GDF15 could promote osteoclast differentiation of the murine macrophage cell line RAW264.7 cells. Molecular investigation uncovered that GDF15 could promote the expression of several pro-inflammatory cytokines and RANKL/OPG ratio in PDLCs, while knockdown of GDF15 impaired their upregulation induced by compressive force. Additionally, administration of recombinant GDF15 protein stimulated the M1-like polarization of RAW264.7 cells and THP-1 induced macrophages. Mechanistically, siRNA-mediated suppression of GDF15 significantly disrupted the nuclear translocation of NF-κB and ERK phosphorylation in response to compressive force. Finally, Yes-associated protein (YAP) was demonstrated to be the upstream regulator of GDF15 in human PDLCs, implying a force-induced YAP-GDF15 regulation mechanism. Overall, these data suggested important roles of GDF15 in the functional modulation of both PDLCs and osteoclast progenitors in response to compressive force, providing novel insights into the molecular mechanism of mechanotransduction during OTM process.

Upregulation of Skeletal Muscle FGF-21 Is Linked to Weight Loss following a Lifestyle Intervention in Humans with Obesity

Skeletal muscle has emerged as an endocrine organ that is capable of secreting myokines that regulate metabolic function via interorgan crosstalk. Two of these myokines are fibroblast growth factor 21 (FGF-21) and growth differentiation factor 15 (GDF15). Both have been described as metabolic mediators that regulate energy homeostasis and insulin sensitivity, thus leading to increased weight loss in obese diabetic rodent models. We hypothesized that aerobic exercise would improve FGF-21 and GDF15 gene and protein expression in insulin resistant skeletal muscle. Older obese subjects (n=15; 66±1 years; 34±1 kg/m2) were recruited and participated in a 12-week supervised aerobic exercise training program (1h/d at ≈ 85% HRmax). Body composition, cardio-metabolic testing and vastus lateralis muscle biopsies were performed before and after the intervention; gene and protein expression were determined by quantitative-real time PCR and Western blot analysis, respectively. Lifestyle intervention increased clamp-derived insulin sensitivity, aerobic capacity (P&amp;lt;0.0001), and fat oxidation (P&amp;lt;0.05), and reduced body weight, BMI and fat mass (P≤0.0001). Exercise training increased expression of skeletal muscle myokines, FGF-21 (gene: P=0.05; protein: P=0.02) and GDF15 (gene: P=0.04). Changes in skeletal muscle FGF-21 were positively correlated with changes in GDF15 (r=0.61, P=0.02), as well as carnitine palmitoyl transferase 1B (r=0.54, P=0.03), and pyruvate dehydrogenase kinase 4 (r=0.52, P=0.05), enzymes important for lipid and glucose oxidation, respectively. The improvement in FGF-21 gene expression was negatively correlated with percent reduction in body weight (r=-0.63, P=0.009), BMI (r=-0.63, P=0.009) and fat mass (r=-0.61, P=0.02). We conclude that exercise training regulates FGF-21 and GDF15 myokine expression, and for FGF-21 this effect may contribute to loss of body fat, suggesting a novel role for FGF-21 in human adipose tissue metabolism. Disclosure A. Mulya: None. H. Zhang: None. J.P. Kirwan: None.

GDF15 Is a Contraction-Induced Myokine That Regulates Pancreatic ß-Cell Function

β-cell dysfunction plays a major role in the onset of type 2 diabetes (T2D). Exercise improves or restores β-cell function in both humans and rodents with T2D. The specific mechanism is unclear. We hypothesized that exercise-induced myokines engage in cross-talk with the pancreas to help regulate β-cell function and mass. To test our hypothesis, differentiated C2C12 myotubes were subjected to electrical pulse stimulation (EPS) to simulate in vivo exercise. EPS-conditioned media from the contracting myotubes significantly elevated glucose-stimulated insulin secretion (GSIS) in β-cells vs. non-EPS control conditions (P&amp;lt;0.05). RNA-sequencing and bioinformatic analysis enabled us to identify Growth Differentiation Factor 15 (GDF15) as a novel contraction-induced myokine that potentially communicates with β-cells. At the cellular level, recombinant GDF15 protein treatment upregulated the GSIS response in β-cells by 55% (P&amp;lt;0.05), with no effect on cellular apoptosis, cytotoxicity or proliferation. Furthermore, qRT-PCR analysis, ELISA, immunoblots, and intracellular assays demonstrated that GDF15 may regulate first-phase insulin secretion by increasing the intracellular ATP/ADP ratio, inhibiting K+ channels and increasing the intracellular Ca2+ without affecting insulin synthesis. Using translational approaches, we found a positive correlation between fasting plasma GDF15 and insulin secretion in prediabetic subjects (R=0.64, P&amp;lt;0.01, n=22). A 6 week supervised functional high-intensity exercise intervention increased fasting plasma GDF15 by 35% in adults with T2D (P&amp;lt;0.01, n=12) and, interestingly, the increase in GDF15 was positively correlated with an increase in the β-cell disposition index (R=0.72, P&amp;lt;0.01, n=12), providing further support that GDF15 may be involved in improving β-cell function. In summary, these findings expand our understanding of skeletal muscle as an endocrine organ and identify GDF15 as a potential myokine for T2D therapy. Disclosure H. Zhang: None. A. Mulya: None. S. Nieuwoudt: None. R. McDowell: None. J.P. Kirwan: None.

Overproduction of growth differentiation factor 15 promotes human rhinovirus infection and virus-induced inflammation in the lung

Human rhinovirus (HRV) is the most common virus contributing to acute exacerbations of chronic obstructive pulmonary disease (COPD) nearly year round, but the mechanisms have not been well elucidated. Recent clinical studies suggest that high levels of growth differentiation factor 15 (GDF15) protein in the blood are associated with an increased yearly rate of all-cause COPD exacerbations. Therefore, in the current study, we investigated whether GDF15 promotes HRV infection and virus-induced lung inflammation. We first examined the role of GDF15 in regulating host defense and HRV-induced inflammation using human GDF15 transgenic mice and cultured human GDF15 transgenic mouse tracheal epithelial cells. Next, we determined the effect of GDF15 on viral replication, antiviral responses, and inflammation in human airway epithelial cells with GDF15 knockdown and HRV infection. Finally, we explored the signaling pathways involved in airway epithelial responses to HRV infection in the context of GDF15. Human GDF15 protein overexpression in mice led to exaggerated inflammatory responses to HRV, increased infectious particle release, and decreased IFN-λ2/3 (IL-28A/B) mRNA expression in the lung. Moreover, GDF15 facilitated HRV replication and inflammation via inhibiting IFN-λ1/IL-29 protein production in human airway epithelial cells. Lastly, Smad1 cooperated with interferon regulatory factor 7 (IRF7) to regulate airway epithelial responses to HRV infection partly via GDF15 signaling. Our results reveal a novel function of GDF15 in promoting lung HRV infection and virus-induced inflammation, which may be a new mechanism for the increased susceptibility and severity of respiratory viral (i.e., HRV) infection in cigarette smoke-exposed airways with GDF15 overproduction.

The metabolic effects of GDF15 are mediated by the orphan receptor GFRAL

Growth/differentiation factor 15 (GDF15), also known as MIC-1, is a distant member of the transforming growth factor-β (TGF-β) superfamily and has been implicated in various biological functions, including cancer cachexia, renal and heart failure, atherosclerosis and metabolism. A connection between GDF15 and body-weight regulation was initially suggested on the basis of an observation that increasing GDF15 levels in serum correlated with weight loss in individuals with advanced prostate cancer. In animal models, overexpression of GDF15 leads to a lean phenotype, hypophagia and other improvements in metabolic parameters, suggesting that recombinant GDF15 protein could potentially be used in the treatment of obesity and type 2 diabetes. However, the signaling and mechanism of action of GDF15 are poorly understood owing to the absence of a clearly identified cognate receptor. Here we report that GDNF-family receptor α-like (GFRAL), an orphan member of the GFR-α family, is a high-affinity receptor for GDF15. GFRAL binds to GDF15 in vitro and is required for the metabolic actions of GDF15 with respect to body weight and food intake in vivo in mice. Gfral-/- mice were refractory to the effects of recombinant human GDF15 on body-weight, food-intake and glucose parameters. Blocking the interaction between GDF15 and GFRAL with a monoclonal antibody prevented the metabolic effects of GDF15 in rats. Gfral mRNA is highly expressed in the area postrema of mouse, rat and monkey, in accordance with previous reports implicating this region of the brain in the metabolic actions of GDF15 (refs. 4,5,6). Together, our data demonstrate that GFRAL is a receptor for GDF15 that mediates the metabolic effects of GDF15.