The Role of Growth Differentiation Factor 15 in Energy Metabolism

The implicated role of GDF15 in gastrointestinal cancer

BACKGROUND

Growth differentiation factor 15 (GDF15), a stress-responsive cytokine from transforming growth factor superfamily, is highly expressed in mammalian tissues, including pancreas, stomach and intestine under pathological conditions. In particular, elevated levels of GDF15 might play an important role in the development and progression of various gastrointestinal cancers (GCs), suggesting its potential as a promising target for disease prediction and treatment.

METHODS

In this review, systematic reviews addressing the role of GDF15 in GCs were updated, along with the latest clinical trials focussing on the GDF15-associated digestive malignancies.

RESULTS

The multiple cellular pathways through which GDF15 is involved in the regulation of physiological and pathological conditions were first summarized. Then, GDF15 was also established as a valuable clinical index, functioning as a predictive marker in diverse GCs. Notably, latest clinical treatments targeting GDF15 were also highlighted, demonstrating its promising potential in mitigating and curing digestive malignancies.

CONCLUSIONS

This review unveils the pivotal roles of GDF15 and its potential as a promising target in the pathogenesis of GCs, which may provide insightful directions for future investigations.

Biomarkers of disability worsening in inactive primary progressive multiple sclerosis

OBJECTIVE

To investigate serum biomarkers of progression in inactive primary progressive multiple sclerosis (PPMS).

METHODS

We measured protein biomarkers (growth differentiation factor-15 (GDF-15), dickkopf-1 (DKK-1), neuron specific enolase (NSE) and cathepsin-D) in serum samples from 39 patients with inactive PPMS included in a clinical trial enrolling people with PPMS (clinicaltrials.gov identifier NCT02913157) and investigated the association of these biomarker levels with clinical disability at baseline and during follow-up. We then performed a meta-analysis of publicly available transcriptomic datasets to investigate the gene expression of these biomarkers in the CNS in progressive MS.

RESULTS

When compared with healthy controls, people with PPMS had higher serum levels of GDF-15, DKK-1 and cathepsin-D at baseline. These findings match those in our meta-analysis which found increased expression of GDF-15 and cathepsin-D in the CNS in progressive MS. At baseline, elevated serum DKK-1 was associated with worse Expanded Disability Status Scale (EDSS) and nine-hole peg test (9HPT) scores. None of the other biomarkers levels significantly correlated with EDSS, Timed 25-Foot Walk Test (T25FWT), 9HPT, or cognitive measures. However, serum GDF-15 and cathepsin-D were higher at baseline in participants who developed worsening disability. Our receiver operating characteristic curve showed that higher serum GDF-15 and cathepsin-D at baseline significantly discriminated between participants who worsened in T25FWT and 9HPT and those who remained stable.

CONCLUSIONS

Patients with PPMS have altered levels of GDF-15, DKK-1 and cathepsin-D in serum, and GDF-15 and cathepsin-D may have predictive value in progression free of inflammatory activity in PPMS.

Growth differentiation factor-15 is an IFN-γ regulated mediator of infection-induced weight loss and the hepatic FGF21 response

Infections are often accompanied by weight loss caused by alterations in host behavior and metabolism, also known as sickness behaviors. Recent studies have revealed that sickness behaviors can either promote or impede survival during infections depending on factors such as the type of infectious pathogen. Nevertheless, we have an incomplete understanding of the underlying mechanisms of sickness behaviors. Furthermore, although the host immune responses to infections have long been known to contribute to the induction of sickness behaviors, recent studies have identified emerging cytokines that are also key regulators of host metabolism during infection and inflammation, such as growth differentiation factor 15 (GDF-15). GDF-15 is a distant member of the TGF-β superfamily that causes weight loss by suppressing appetite and food consumption and causing emesis. These effects require activation of neurons that express the only known GDF-15 receptor, the GFRAL receptor. GDF-15 also functions in the periphery including the induction of ketogenesis and immunoregulation. Nevertheless, the functions and regulation of GDF-15 during live infections is not yet known. Murine infection with avirulent Toxoplasma gondii is an established model to understand infection-induced weight loss. Past studies have determined that acute T. gondii infection causes weight loss due to diminished food consumption and increased energy expenditure through unknown mechanisms. Additionally, our lab previously demonstrated that T. gondii causes upregulation in serum GDF-15 in an IFN-γ-dependent manner during the post-acute phase of the infection. In this study, we interrogated the in-vivo functions and immune regulation of GDF-15 during Toxoplasma gondii infection. First, we found that in wild-type mice, acute T. gondii infection caused a significant weight loss that is preceded by elevation of serum levels of IFN-γ and GDF-15. To determine whether IFN-γ regulates GDF-15, we neutralized IFN-γ on days 5 and 6 and measured GDF-15 on day 7 and found that serum but not tissue levels of GDF-15 decreased after IFN-γ neutralization. Additionally, exogenous IFN-γ was sufficient to elevate serum GDF-15 in the absence of infection. Next, we compared the outcomes of T. gondii infection between WT and Gdf15-/- mice. We observed that the weight trajectories were declining in WT mice while they were increasing in Gdf15-/-mice during the acute phase of the infection. This difference in trajectories extended throughout the chronic infection resulting to an overall weight loss relative to initial weights in WT mice but not Gdf15-/-mice. Then, we determined that GDF-15 is not essential for survival and immunoregulation during T. gondii infection. We also demonstrated that GDF-15 is required for the induction of FGF21, stress-induced cytokine with prominent roles in regulating host metabolism. Finally, we discovered a cytokine cascade IFN-γ-GDF-15-FGF21 that is likely involved in the regulation of host metabolism. Overall, our study provides evidence that IFN-γ contributes to the regulation of host metabolism during infection by inducing GDF-15 and FGF21. GDF-15 orchestrates changes in host metabolism that supports the host immune response in clearing the infection. These physiological alterations induce FGF21, which in turn, orchestrates the adaptive responses to the effects of GDF-15, which can be detrimental when protracted.

Serum growth differentiation factor-15 (GDF-15) is a biomarker of cardiac manifestations in children with COVID-19

BACKGROUND

COVID-19 leads to severe overwhelming inflammation in some patients mediated by various cytokines (cytokine storm) that usually leads to severe illness accompanied by cardiovascular manifestations. Growth differentiation factor-15 is a cytokine induced by stress and is associated with inflammatory processes in the lung and heart. This study aimed to measure the level of serum growth differentiation factor (GDF-15) in children with COVID-19 and to correlate it with the disease severity, cardiac affection, and the outcome of COVID-19.

METHODS

A cross-sectional study was conducted on 144 children; 72 children diagnosed with COVID-19, and 72 healthy children. The severity of COVID-19 was assessed clinically, laboratory, and radiologically. Echocardiography was done within 48 h of admission for COVID-19 patients. Serum GDF-15 was measured by ELISA for both patients and controls.

RESULTS

Serum GDF-15 level was significantly higher in patients with COVID-19 than in controls (p < 0.01). In COVID-19 patients with severe clinical grading, those who were hospitalized in the PICU, and those who died, serum GDF-15 levels were greater. individuals with cardiac manifestations exhibited significantly higher serum GDF-15 levels than individuals without them. In children with COVID-19, increased GDF-15 was correlated to poorer ejection fraction and higher INR using multivariate linear regression analysis.

CONCLUSION

Serum GDF-15 is a promising biomarker of COVID-19, it can be used as a predictor of cardiac manifestations in children with COVID-19 and severe disease.

GDF15 enhances body weight and adiposity reduction in obese mice by leveraging the leptin pathway

GDF15 regulates its anorexic effects through the hindbrain area postrema (AP) and nucleus of the solitary tract (NTS) neurons where its receptor, glial-derived neurotrophic factor receptor alpha-like (GFRAL), is expressed. The actions of GDF15 may interact with other appetite regulators elevated in obesity, such as leptin. Here, we report that in mice with high-fat-diet-induced obesity (HFD), the combined infusion of GDF15 and leptin causes significantly greater weight and adiposity loss than either treatment alone, indicating potentiation between GDF15 and leptin. Furthermore, obese, leptin-deficient ob/ob mice are less responsive to GDF15, as are normal mice treated with a competitive leptin antagonist. GDF15 and leptin induce more hindbrain neuronal activation in HFD mice than either treatment alone does. We report extensive connections between GFRAL- and LepR-expressing neurons and find LepR knockdown in the NTS to reduce the GDF15-mediated activation of AP neurons. Overall, these findings suggest that leptin signaling pathways in the hindbrain increase GDF15's metabolic actions.

A long-acting GDF15 analog causes robust, sustained weight loss and reduction of food intake in an obese nonhuman primate model

Growth Differentiation Factor-15 (GDF15) is a circulating polypeptide linked to cellular stress and metabolic adaptation. GDF15's half-life is ~3 h and activates the glial cell line-derived neurotrophic factor family receptor alpha-like (GFRAL) receptor expressed in the area postrema. To characterize sustained GFRAL agonism on food intake (FI) and body weight (BW), we tested a half-life extended analog of GDF15 (Compound H [CpdH]) suitable for reduced dosing frequency in obese cynomolgus monkeys. Animals were chronically treated once weekly (q.w.) with CpdH or long-acting GLP-1 analog dulaglutide. Mechanism-based longitudinal exposure-response modeling characterized effects of CpdH and dulaglutide on FI and BW. The novel model accounts for both acute, exposure-dependent effects reducing FI and compensatory changes in energy expenditure (EE) and FI occurring over time with weight loss. CpdH had linear, dose-proportional pharmacokinetics (terminal half-life ~8 days) and treatment caused exposure-dependent reductions in FI and BW. The 1.6 mg/kg CpdH reduced mean FI by 57.5% at 1 week and sustained FI reductions of 31.5% from weeks 9-12, resulting in peak reduction in BW of 16 ± 5%. Dulaglutide had more modest effects on FI and peak BW loss was 3.8 ± 4.0%. Longitudinal modeling of both the FI and BW profiles suggested reductions in BW observed with both CpdH and dulaglutide were fully explained by exposure-dependent reductions in FI without increase in EE. Upon verification of the pharmacokinetic/pharmacodynamic relationship established in monkeys and humans for dulaglutide, we predicted that CpdH could reach double digit BW loss in humans. In summary, a long-acting GDF15 analog led to sustained reductions in FI in overweight monkeys and holds potential for effective clinical obesity pharmacotherapy.

Metformin and growth differentiation factor 15 (GDF15) in type 2 diabetes mellitus: A hidden treasure

Type 2 diabetes mellitus (T2DM) is a chronic endocrine disorder due to the reduction of insulin sensitivity and relative deficiency of insulin secretion. Growth differentiation factor 15 (GDF15) belongs to the transforming growth factor beta (TGF-β) superfamily and was initially identified as macrophage inhibitory cytokine-1 (MIC-1). GDF15 is considered a cytokine with an anti-inflammatory effect and increases insulin sensitivity, reduces body weight, and improves clinical outcomes in diabetic patients. GDF15 acts through stimulation of glial-derived neurotrophic factor (GDNF) family receptor α-like (GFRAL), which is highly expressed in the brain stem to induce taste aversion. Metformin belongs to the group of biguanides that are derived from the plant Galega officinalis. It is interesting to note that metformin is an insulin-sensitizing agent used as a first-line therapy for T2DM that has been shown to increase the circulating level of GDF15. Thus, the present review aims to determine the critical association of the GDF15 biomarker in T2DM and how metformin agents affect it. This review illustrates that metformin activates GDF15 expression, which reduces appetite and leads to weight loss in both diabetic and nondiabetic patients. However, the present review cannot give a conclusion in this regard. Therefore, experimental, preclinical, and clinical studies are warranted to confirm the potential role of GDF15 in T2DM patients.

The Potential Role of Growth Differentiation Factor 15 in COVID-19: A Corollary Subjective Effect or Not?

Coronavirus disease 2019 (COVID-19) is primarily caused by various forms of severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) variants. COVID-19 is characterized by hyperinflammation, oxidative stress, multi-organ injury (MOI)-like acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Different biomarkers are used in the assessment of COVID-19 severity including D-dimer, ferritin, lactate dehydrogenase (LDH), and hypoxia-inducible factor (HIF). Interestingly, growth differentiation factor 15 (GDF15) has recently become a potential biomarker correlated with the COVID-19 severity. Thus, this critical review aimed to determine the critical association between GDF15 and COVID-19. The perfect function of GDF15 remains not well-recognized; nevertheless, it plays a vital role in controlling cell growth, apoptosis and inflammatory activation. Furthermore, GDF15 may act as anti-inflammatory and pro-inflammatory signaling in diverse cardiovascular complications. Furthermore, the release of GDF15 is activated by various growth factors and cytokines including macrophage colony-stimulating factor (M-CSF), angiotensin II (AngII) and p53. Therefore, higher expression of GDF15 in COVID-19 might a compensatory mechanism to stabilize and counteract dysregulated inflammatory reactions. In conclusion, GDF15 is an anti-inflammatory cytokine that could be associated with the COVID-19 severity. Increased GDF15 could be a compensatory mechanism against hyperinflammation and exaggerated immune response in the COVID-19. Experimental, preclinical and large-scale clinical studies are warranted in this regard.

Investigating the combination of plasma amyloid-beta and geroscience biomarkers on the incidence of clinically meaningful cognitive decline in older adults

We investigated combining a core AD neuropathology measure (plasma amyloid-beta [Aβ] _42/40) with five plasma markers of inflammation, cellular stress, and neurodegeneration to predict cognitive decline. Among 401 participants free of dementia (median [IQR] age, 76 [73-80] years) from the Multidomain Alzheimer Preventive Trial (MAPT), 28 (7.0%) participants developed dementia, and 137 (34.2%) had worsening of clinical dementia rating (CDR) scale over 4 years. In the models utilizing plasma Aβ alone, a tenfold increased risk of incident dementia (nonsignificant) and a fivefold increased risk of worsening CDR were observed as each nature log unit increased in plasma Aβ levels. Models incorporating Aβ plus multiple plasma biomarkers performed similarly to models included Aβ alone in predicting dementia and CDR progression. However, improving Aβ model performance for composite cognitive score (CCS) decline, a proxy of dementia, was observed after including plasma monocyte chemoattractant protein 1 (MCP1) and growth differentiation factor 15 (GDF15) as covariates. Participants with abnormal Aβ, GDF15, and MCP1 presented higher CCS decline (worsening cognitive function) compared to their normal-biomarker counterparts (adjusted β [95% CI], - 0.21 [- 0.35 to - 0.06], p = 0.005). In conclusion, our study found limited added values of multi-biomarkers beyond the basic Aβ models for predicting clinically meaningful cognitive decline among non-demented older adults. However, a combined assessment of inflammatory and cellular stress status with Aβ pathology through measuring plasma biomarkers may improve the evaluation of cognitive performance.

Understanding the molecular basis of anorexia and tissue wasting in cancer cachexia

Cancer cachexia syndrome is a major cause of morbidity and mortality in cancer patients in the advanced stage. It is a devastating disorder characterized by nutritional impairment, weakness, and wasting, and it affects treatment success and quality of life. Two major symptoms of cancer cachexia are anorexia and weight loss. Weight loss in cachexia is not reversed through increased food intake, suggesting that anorexia and weight loss in cancer patients are regulated by independent molecular mechanisms. Although the wasting phenotype mostly occurs in skeletal muscle and adipose tissue, other organs, such as the brain, liver, pancreas, heart, and gut, are also involved in cachexia. Thus, cachexia is a multiorgan syndrome. Although the molecular basis of cancer cachexia-induced weight loss is known, the mechanism underlying anorexia is poorly understood. Here, we highlight our recent discovery of a new anorexia mechanism by which a tumor-derived humoral factor induces cancer anorexia by regulating feeding-related neuropeptide hormones in the brain. Furthermore, we elucidated the process through which anorexia precedes tissue wasting in cachexia. This review article aims to provide an overview of the key molecular mechanisms of anorexia and tissue wasting caused by cancer cachexia.

Tumors can release factors that cause anorexia and weight loss in cancer patients, negatively impacting quality of life and treatment success. Patients with this condition, known as cachexia, can lose their appetite and be unable to gain weight even if they eat more. Although cancer cachexia directly causes the death of up to 20% of cancer patients, the mechanisms are poorly understood. Eunbyul Yeom and Kweon Yu at The Korea Research Institute of Bioscience and Biotechnology, Daejon, South Korea have reviewed the causes of cancer cachexia, highlighting their recent discovery that tumors produce a signaling molecule that induces anorexia by disrupting hunger signaling in the brain. Improving our understanding of the mechanisms underlying cancer cachexia may help in development of treatments.

The Role of GDF15 as a Myomitokine

Growth differentiation factor 15 (GDF15) is a cytokine best known for affecting systemic energy metabolism through its anorectic action. GDF15 expression and secretion from various organs and tissues is induced in different physiological and pathophysiological states, often linked to mitochondrial stress, leading to highly variable circulating GDF15 levels. In skeletal muscle and the heart, the basal expression of GDF15 is very low compared to other organs, but GDF15 expression and secretion can be induced in various stress conditions, such as intense exercise and acute myocardial infarction, respectively. GDF15 is thus considered as a myokine and cardiokine. GFRAL, the exclusive receptor for GDF15, is expressed in hindbrain neurons and activation of the GDF15–GFRAL pathway is linked to an increased sympathetic outflow and possibly an activation of the hypothalamic-pituitary-adrenal (HPA) stress axis. There is also evidence for peripheral, direct effects of GDF15 on adipose tissue lipolysis and possible autocrine cardiac effects. Metabolic and behavioral outcomes of GDF15 signaling can be beneficial or detrimental, likely depending on the magnitude and duration of the GDF15 signal. This is especially apparent for GDF15 production in muscle, which can be induced both by exercise and by muscle disease states such as sarcopenia and mitochondrial myopathy.

The metabolic role of spermidine in obesity: Evidence from cells to community

Spermidine is a natural polyamine existing in all living cells known to play an important role in cellular functions. Recently, several studies have reported the effect of alterations in the spermidine pool on metabolic pathways. It has been shown that activation of spermidine/spermine N-1-acetyl-transferase (SSAT), the rate-limiting enzyme in polyamine catabolism, improved glucose and lipid metabolism. In addition, spermidine supplementation has been shown to protect against diet-induced obesity in animal models. However, some clinical studies demonstrated that polyamine levels are increased in childhood obesity and metabolic syndrome patients with type 2 diabetes (T2DM), while polyamine-rich food is associated with a lower incidence of cardiovascular disease (CVD). Therefore, this review aims to summarize and discuss the evidence from in vitro, in vivo and clinical studies on the possible roles of spermidine on metabolic pathways under physiological and obese conditions. All consistent and inconsistent findings are discussed and further studies aiming to fill any gaps in the knowledge are proposed.

Neurological & psychological aspects of Barth syndrome: Clinical manifestations and potential pathogenic mechanisms

Barth syndrome is a rare X-linked multisystem mitochondrial disease that is caused by variants in the tafazzin gene leading to deficient and abnormal cardiolipin. Previous research has focused on the cardiomyopathy and neutropenia in individuals with Barth syndrome, yet just as common are the least explored neurological aspects of Barth syndrome. This review focuses on the major neuropsychological and neurophysiological phenotypes that affect the quality of life of individuals with Barth syndrome, including difficulties in sensory perception and feeding, fatigue, and cognitive and psychological challenges. We propose selected pathogenetic mechanisms underlying these phenotypes and draw parallels to other relevant disorders. Finally, avenues for future research are also suggested.

Effects of Exercise Intervention on Mitochondrial Stress Biomarkers in Metabolic Syndrome Patients: A Randomized Controlled Trial

Metabolic syndrome (MetS) pathogenesis involves oxidative stress associated with mitochondrial dysfunction, which triggers integrated stress responses via various compensatory metabolic modulators like mitokines and hepatokines. However, the regulatory mechanisms underlying the exercise-derived benefits with respect to mitokines and hepatokines (potential MetS biomarkers) are unknown. Thus, we investigated the effects of exercise training on MetS biomarkers and their associations with clinical parameters. In this single-center trial, 30 women with MetS were randomly assigned to 12-week supervised exercise or control groups (1:1) and compared with 12 age-matched healthy volunteers. All participants completed the study except one subject in the control group. Expectedly, serum levels of the mitokines, fibroblast growth factor-21 (FGF21), growth differentiation factor-15 (GDF15), and the hepatokine, angiopoietin-like 6 (ANGPTL6), were higher in MetS patients than in healthy volunteers. Moreover, their levels were markedly attenuated in the exercise group. Further, exercise-mediated changes in serum FGF21 and GDF15 correlated with changes in the homeostasis model of assessment of insulin resistance (HOMA-IR) and appendicular lean mass (ALM), respectively. Additionally, changes in serum triglycerides and ANGPTL6 were correlated with changes in leptin. Aberrant mitokine and hepatokine levels can be rectified by relieving metabolic stress burden. Therefore, exercise training may reduce the need for the compensatory upregulation of MetS metabolic modulators by improving gluco-lipid metabolism.

GDF15/GFRAL Pathway as a Metabolic Signature for Cachexia in Patients with Cancer

Cachexia is a metabolic mutiny that directly reduces life expectancy in chronic conditions such as cancer. The underlying mechanisms associated with cachexia involve inflammation, metabolism, and anorexia. Therefore, the need to identify cachexia biomarkers is warranted to better understand catabolism change and assess various therapeutic interventions. Among inflammatory proteins, growth differentiation factor-15 (GDF15), an atypical transforming growth factor-beta (TGF-β) superfamily member, emerges as a stress-related hormone. In inflammatory conditions, cardiovascular diseases, and cancer, GDF15 is a biomarker for disease outcome. GDF15 is also implicated in energy homeostasis, body weight regulation, and plays a distinct role in cachexia. The recent discovery of its receptor, glial cell line-derived neurotrophic factor (GDNF) family receptor α-like (GFRAL), sheds light on its metabolic function. Herein, we critically review the mechanisms involving GDF15 in cancer cachexia and discuss therapeutic interventions to improve outcomes in people living with cancer.