GDF15: emerging biology and therapeutic applications for obesity and cardiometabolic disease

GDF15 promotes trophoblast invasion and pregnancy success via the BMPR1A/BMPR2/p-SMAD1 pathway: Implications for recurrent miscarriage

Insufficient invasion of extravillous trophoblasts (EVTs) is associated with adverse pregnancy outcomes, including recurrent miscarriage (RM). Dysregulated expression of growth differentiation factor 15 (GDF15) has been implicated in RM, but the underlying mechanism remains unclear. This study investigated the role of GDF15 in EVTs function and pregnancy outcomes. Spearman correlation analysis revealed a positive correlation between GDF15 and both BMPR1A and BMPR2 in EVTs. Furthermore, GDF15, BMPR1A, BMPR2, and phosphorylated SMAD1 (p-SMAD1) expression were significantly reduced in placental tissue from RM patients compared to Normal controls. Mechanistically, GDF15 activated the p-SMAD1 signaling pathway, inducing expression of its downstream targets, ID1 and Snail, and enhancing migratory and invasive activity in HTR-8/SVneo cells through interaction with the BMPR1A-BMPR2 receptor complex. Eriodictyol, a small molecule activator of BMPR2, was identified and shown to improve pregnancy outcomes in a mouse model of lipopolysaccharide (LPS)-induced early pregnancy loss (EPL). Eriodictyol can also enhance EVTs migration and invasion as well as activated the p-SMAD1 pathway by activating BMPR2. In conclusion, this study identifies BMPR1A as a receptor for GDF15 in EVTs and demonstrates that GDF15 promotes EVTs invasion and improves pregnancy outcomes via the BMPR1A/BMPR2/p-SMAD1 signaling axis. Eriodictyol, acting as a BMPR2 agonist, may offer a novel therapeutic strategy for preventing early pregnancy loss.

Plasma proteomic signatures for type 2 diabetes and related traits in the UK Biobank cohort

OBJECTIVE

The plasma proteome holds promise as a diagnostic and prognostic tool that can accurately reflect complex human traits and disease processes. We assessed the ability of proteins to predict type 2 diabetes and related traits.

STUDY DESIGN

We analyzed clinical, genetic, and proteomic data from three UK Biobank subcohorts for associations with truncal fat, estimated maximum oxygen consumption (VO2max), and type 2 diabetes. Using least absolute shrinkage and selection operator (LASSO) regression, we compared predictive performance of each trait between data types. The benefit of proteomic signatures (PSs) over the type 2 diabetes clinical risk score, QDiabetes was evaluated. Two-sample Mendelian randomization (MR) identified potentially causal proteins for each trait.

RESULTS

LASSO-derived PSs improved prediction of truncal fat and VO2max over clinical and genetic factors. We observed a modest improvement in type 2 diabetes prediction over the QDiabetes score when combining a PS derived for type 2 diabetes that was further augmented with fat- and fitness-associated PSs. Two-sample MR identified a few proteins as potentially causal for each trait.

CONCLUSION

Plasma PSs modestly improve type 2 diabetes prediction beyond clinical and genetic factors. Candidate causally associated proteins deserve further study as potential novel therapeutic targets for type 2 diabetes.

Super-resolution imaging informed scRNA sequencing analysis reveals the critical role of GDF15 in rejuvenating aged hematopoietic stem cells

Although changes in mitochondrial morphology consistently associated with the aging of hematopoietic stem cells (HSCs), the specific molecular and cellular mechanisms involved are partially unclear. Live-cell super-resolution (SR) microscopy has been used to identify distinct HSC subsets that characterized by mitochondria unique morphologies and spatial distributions. The integration of SR microscopy with single-cell RNA sequencing enabled the classification of approximately 200 HSCs from young and aged mice into 5 discrete clusters. These clusters displayed molecular profiles that corresponded to the observed mitochondria states. An integrated approach combining RNA biomarker analysis and potential regulon assessment revealed previously unrecognized roles of GDF15 in mediating mitochondrial signals and morphologies that influence HSC fate. Thus, combining SR imaging with a bioinformatics pipeline provides an effective method for identifying key molecular players in specific phases of cellular transition, even with a relatively small dataset.

HIIT may ameliorate inter-organ crosstalk between liver and hypothalamus of HFD-induced MAFLD rats; A two-phase study to investigate the effect of exercise intensity as a stressor

Previous studies demonstrate that GDF15 and its related signaling activators may be affected by exercise training, leading to the suppression of inflammatory factors and the promotion of immune-metabolic balance. Therefore, the purpose of the study was to evaluate the effect of high-intensity interval training (HIIT) on amelioration of inter-organ crosstalk between liver and hypothalamus of the high-fat diet (HFD)-induced metabolic dysfunction-associated fatty liver disease (MAFLD) rats in a two-phase study. In this regard, rats were initially divided into two groups, the normal diet-inactive (NS) and the HFD groups. HFD course lasted 12 weeks to induce MAFLD in the latter group. After ensuring the induction of MAFLD, 25 rats were divided into three groups: the HFD-inactive group (HS), the HFD-HIIT group (HH), as well as the HFD-aerobic group (HA). The training interventions were consistently applied over a period of eight weeks, five days a week, with each session lasting 40-60 min, and the duration of the whole research was 21 weeks. The results of this study displayed that HIIT intervention promotes hypothalamic Gdf15 gene expression and there were similar alterations in genes expression of Foxo1 and Akt2. Moreover, our results confirmed that HIIT ameliorated hypothalamic NFKB gene expression and there was a similar trend in genes expression of Tnfa and Il1b following both HIIT as well as aerobic training protocols. Taking these findings together, it is concluded that interventions, particularly exercise training, uniquely contribute to the reduction of hypothalamic-associated inflammatory responses that result in prolonged and chronic increases in GDF15.

Transcoronary study of biomarkers in patients with heart failure: Insights into intracardiac production

AIMS

Biomarkers are pivotal in the management of heart failure (HF); however, their lack of cardiac specificity could limit clinical utility. This study aimed to investigate the transcoronary changes and intracardiac production of these biomarkers.

METHODS

Transcoronary gradients for B-type natriuretic peptide (BNP) and five novel biomarkers-galectin-3 (Gal-3), soluble suppression of tumourigenicity 2 (sST2), tissue inhibitor of metalloproteinase 1 (TIMP-1), growth differentiation factor 15 (GDF-15) and myeloperoxidase (MPO)-were determined using femoral artery (FA) and coronary sinus (CS) samples from 30 HF patients and 10 non-HF controls. Intracardiac biomarker production was assessed in an HF canine model using real-time quantitative PCR (qPCR) and western blot (WB) analysis.

RESULTS

Compared with the control group, levels of all detected biomarkers were significantly elevated in the HF group, while transcoronary gradients were only observed for BNP, Gal-3 and TIMP-1 levels in the HF group (BNP: FA: 841.5 ± 727.2 ng/mL vs. CS: 1132.0 ± 959.1 ng/mL, P = 0.005; Gal-3: FA: 9.5 ± 3.0 ng/mL vs. CS: 19.7 ± 16.4 ng/mL, P = 0.002; and TIMP-1: FA: 286.7 ± 68.9 ng/mL vs. CS: 377.3 ± 108.9 ng/mL, P = 0.001). Real-time qPCR and WB analysis revealed significant elevation of BNP, Gal-3 and TIMP-1 in the cardiac tissues of the HF group relative to other groups.

CONCLUSIONS

This study provided evidence of transcoronary changes in BNP, Gal-3 and TIMP-1 levels in HF patients, offering insights into their intracardiac production. These findings enhance the understanding of the biology of these biomarkers and may inform their clinical application.

The immune system in cardiovascular diseases: from basic mechanisms to therapeutic implications

Immune system plays a crucial role in the physiological and pathological regulation of the cardiovascular system. The exploration history and milestones of immune system in cardiovascular diseases (CVDs) have evolved from the initial discovery of chronic inflammation in atherosclerosis to large-scale clinical studies confirming the importance of anti-inflammatory therapy in treating CVDs. This progress has been facilitated by advancements in various technological approaches, including multi-omics analysis (single-cell sequencing, spatial transcriptome et al.) and significant improvements in immunotherapy techniques such as chimeric antigen receptor (CAR)-T cell therapy. Both innate and adaptive immunity holds a pivotal role in CVDs, involving Toll-like receptor (TLR) signaling pathway, nucleotide-binding oligomerization domain-containing proteins 1 and 2 (NOD1/2) signaling pathway, inflammasome signaling pathway, RNA and DNA sensing signaling pathway, as well as antibody-mediated and complement-dependent systems. Meanwhile, immune responses are simultaneously regulated by multi-level regulations in CVDs, including epigenetics (DNA, RNA, protein) and other key signaling pathways in CVDs, interactions among immune cells, and interactions between immune and cardiac or vascular cells. Remarkably, based on the progress in basic research on immune responses in the cardiovascular system, significant advancements have also been made in pre-clinical and clinical studies of immunotherapy. This review provides an overview of the role of immune system in the cardiovascular system, providing in-depth insights into the physiological and pathological regulation of immune responses in various CVDs, highlighting the impact of multi-level regulation of immune responses in CVDs. Finally, we also discuss pre-clinical and clinical strategies targeting the immune system and translational implications in CVDs.

Effects of exercise conducted prior to phenylketonuria-type meal on appetite, satiety hormones and energy expenditure: a randomised cross-over trial

BACKGROUND/OBJECTIVES

Individuals with phenylketonuria (PKU) are at increased risk for obesity, possibly due to reduced satiety induced by a PKU diet that is low protein and high carbohydrate. It is unclear how exercise alters postprandial satiety after a PKU-like meal. The objective was to examine changes in postprandial satiety, satiety hormone concentrations, energy expenditure and substrate oxidation in response to acute treadmill exercise following a PKU-like meal.

SUBJECTS/METHODS

Sixteen males (mean age [±SD]: 26.5 ± 4.8 years; BMI: 23.7 ± 3.2 kg/m2) participated in a randomized cross-over trial with two conditions: exercise and control. Both trials involved consuming a PKU-like meal comprising naturally low-protein foods, a special low-protein food and a protein substitute. In the exercise trial, participants exercised at 60% of maximal oxygen uptake for 1 h before the meal; in the control trial, they rested. Satiety agents (peptide YY [PYY], glucagon-like peptide-1 [GLP-1] and growth differentiation factor-15 [GDF-15]), appetite, energy expenditure, fat oxidation and carbohydrate oxidation were measured.

RESULTS

Mean (±SE) appetite and postprandial PYY and GLP-1 concentrations were unaffected by exercise (P ≥ 0.279). However, GDF-15 was higher in the exercise trial (control: 288 ± 25 pg/mL vs. exercise: 322 ± 24 pg/mL; P = 0.002). Exercise increased fat oxidation (P = 0.013) and decreased carbohydrate oxidation post-meal (P = 0.022), with concomitantly lower RER (P = 0.005). Energy expenditure rose during exercise (P < 0.001), but no difference occurred postprandially (P = 0.543).

CONCLUSIONS

Acute exercise prior to a PKU-like meal does not affect postprandial GLP-1 and PYY concentrations compared to control but GDF-15 was increased and RER was reduced, potentially improving appetite regulation.

Age-Associated Increase in Growth Differentiation Factor 15 Levels Correlates With Central Arterial Stiffness and Predicts All-Cause Mortality in a Sardinian Population Cohort

BACKGROUND

Growth differentiation factor 15 (GDF-15) levels are emerging as a candidate biomarker of aging. The present study aimed to: (1) characterize the association of GDF-15 with the continuum of arterial stiffening, assessed as carotid-femoral pulse wave velocity, as age increases; (2) determine the predictive role of serum GDF-15 levels on mortality; and (3) identify genetic determinants of serum GDF-15 levels.

METHODS AND RESULTS

Serum levels of GDF-15 and established cardiovascular risk factors, including pulse wave velocity, were assessed in a large (4736 individual) Sardinian population. Serum levels of GDF-15, which can be reliably measured repeatedly over time, increase with age; are associated with a stiffer aorta; "mediate" a large proportion of the age-associated increase in arterial stiffness; pose risks because of their association with greater mortality; and are significantly associated with the variant rs11549407, which causes thalassemia major in homozygosity.

CONCLUSIONS

Because of its consistent ability to predict functional and clinical outcomes, including all-cause mortality, we conclude that GDF-15 serum levels serve as a robust biomarker for the continuum from health to the emergence of clinical disease during aging and, subsequently, to the likelihood of mortality.

Interpretable machine learning leverages proteomics to improve cardiovascular disease risk prediction and biomarker identification

BACKGROUND

Cardiovascular diseases (CVDs) rank amongst the leading causes of long-term disability and mortality. Predicting CVD risk and identifying associated genes are crucial for prevention, early intervention, and drug discovery. The recent availability of UK Biobank Proteomics data enables investigation of blood proteins and their association with a variety of diseases. We sought to predict 10 year CVD risk using this data modality and known CVD risk factors.

METHODS

We focused on the UK Biobank participants that were included in the UK Biobank Pharma Proteomics Project. After applying exclusions, 50,057 participants were included, aged 40-69 years at recruitment. We employed the Explainable Boosting Machine (EBM), an interpretable machine learning model, to predict the 10 year risk of primary coronary artery disease, ischemic stroke or myocardial infarction. The model had access to 2978 features (2923 proteins and 55 risk factors). Model performance was evaluated using 10-fold cross-validation.

RESULTS

The EBM model using proteomics outperforms equation-based risk scores such as PREVENT, with a receiver operating characteristic curve (AUROC) of 0.767 and an area under the precision-recall curve (AUPRC) of 0.241; adding clinical features improves these figures to 0.785 and 0.284, respectively. Our models demonstrate consistent performance across sexes and ethnicities and provide insights into individualized disease risk predictions and underlying disease biology.

CONCLUSIONS

In conclusion, we present a more accurate and explanatory framework for proteomics data analysis, supporting future approaches that prioritize individualized disease risk prediction, and identification of target genes for drug development.

Differential effects of bariatric surgery on circulating GDF15 and FGF21 levels: Implications for glycemic status and weight loss outcomes

BACKGROUND

Type 2 diabetes (T2D) is a comorbidity commonly associated with obesity. Elevated concentrations of growth differentiation factor 15 (GDF15) and fibroblast growth factor 21 (FGF21) are associated with these conditions, making both cytokines interesting candidates to combat them. This study aimed to analyse the relationship between changes in plasma GDF15 and FGF21 levels and the resolution of T2D or obesity improvements after bariatric surgery.

METHODS

Plasma samples from 104 patients (52 with obesity and normoglycemia and 52 with obesity and impaired glucose tolerance or T2D) were analysed before and after Roux-en-Y-gastric bypass surgery.

RESULTS

Plasma GDF15 levels increased significantly after bariatric surgery in patients with obesity and normoglycemia (p < 0.01), as well as in those with obesity and impaired glucose tolerance or T2D (p < 0.05). This increase was significant in patients analysed up to 8 months after surgery in both groups (p < 0.01) but not in those analysed between 8 to 15 months after surgery, suggesting that GDF15 concentrations exhibit an early increase after surgery but may return to baseline levels over time. In contrast, plasma FGF21 levels after bariatric surgery decreased significantly in patients with impaired glucose tolerance or T2D (p < 0.05). Pre-surgery FGF21 concentrations were negatively correlated with the percentage of excess weight loss and the percentage of fat loss.

CONCLUSIONS

GDF15 and FGF21 exhibit a different behaviour after Roux-en-Y-gastric bypass surgery, with FGF21 being more closely associated with glycemic status and weight loss. Elevated pre-surgery FGF21 concentrations could predict a higher difficulty in losing the excess weight after surgery.

Hepatic estrogen-related receptor gamma is a key regulator of GDF15 production in acute and chronic liver injury

AIMS

Growth differentiation factor 15 (GDF15) is a stress-induced hepatokine with emerging roles in liver injury. Estrogen-related receptor γ (ERRγ), a nuclear receptor regulating mitochondrial function and metabolic stress, has also been implicated in various liver injury conditions. However, the regulatory interplay between ERRγ and GDF15 remains unclear. This study investigates the molecular mechanisms underlying GDF15 expression and secretion in the liver, focusing on the role of ERRγ during acute and chronic liver injury.

MATERIALS AND METHODS

Wild-type and hepatocyte-specific ERRγ knockout (ERRγ-LKO) mice were administered with a single dose of carbon tetrachloride (CCl4) or fed an alcohol-containing diet for 4 weeks to establish acute or chronic liver injury models, respectively. ERRγ was overexpressed through an adenoviral construct (Ad-ERRγ). The ERRγ-specific inverse agonist GSK5182 was employed to inhibit the transactivation of ERRγ. The luciferase reporter assays were used to assess the binding of ERRγ protein to the regulatory region of GDF15 gene.

KEY FINDINGS

Hepatic ERRγ and GDF15 gene expression, and GDF15 protein secretion were significantly elevated in both acute and chronic liver injury. Adenovirus-mediated overexpression of ERRγ is sufficient to substantially increase hepatic GDF15 expression and secretion. Genetic ablation of ERRγ expression or pharmacological inhibition of ERRγ transactivation substantially inhibited the upregulation of hepatic GDF15 expression and production in both acute and chronic liver injury. Furthermore, reporter assays showed that ERRγ, but not ERRα or ERRβ, directly binds to and activates the GDF15 gene promoter.

SIGNIFICANCE

Our findings highlight the crucial role of ERRγ in transcriptional regulation of GDF15 gene expression and production in response to liver damage. Understanding the regulatory mechanisms of GDF15 expression could lead to new therapeutic targets for protecting the liver from various types of injuries and associated diseases.

Dual-responsive nanoparticles targeting ACE-II senescence for therapeutic mitigation of acute lung injury

Acute lung injury (ALI) is a life-threatening condition characterized by severe pulmonary dysfunction, with alveolar type II epithelial cell (ACE-II) senescence playing a pivotal role in its progression. In this study, we developed pH/reactive oxygen species (ROS) dual-responsive nanoparticles (GNPsanti-SP-C) for the targeted delivery of Growth Differentiation Factor 15 (GDF15) to counteract ACE-II senescence. These nanoparticles (NPs) effectively activate the AMP-activated protein kinase (AMPK)/Sirtuin 1 (SIRT1) signaling pathway, inducing the mitochondrial unfolded protein response (UPRmt) and reversing senescence-associated cellular dysfunction. GNPsanti-SP-C were systematically engineered and demonstrated robust pH/ROS sensitivity, efficient GDF15 release, and precise ACE-II targeting. In lipopolysaccharide (LPS)-induced ALI mouse model, GNPsanti-SP-C treatment significantly mitigated lung injury, reduced inflammatory responses, and enhanced pulmonary function, as evidenced by decreased inflammatory markers, lung edema, and improved histopathology. Single-cell transcriptomic and proteomic analyses revealed increased ACE-II cell populations, reduced expression of senescence markers, and upregulation of AMPK/SIRT1 signaling. In vitro studies further demonstrated that UPRmt activation is associated with the NPs' therapeutic effects, suggesting a potential role in their mechanism of action. These findings demonstrate the potential of GDF15-loaded dual-responsive NPs as an innovative strategy to address cellular senescence and alleviate ALI-associated pulmonary damage.

Human Plasma Proteomics Links Modifiable Lifestyle Exposome to Disease Risk

Environmental exposures influence disease risk, yet their underlying biological mechanisms remain poorly understood. We present the Human Exposomic Architecture of the Proteome (HEAP), a framework and resource integrating genetic, exposomic, and proteomic data to uncover how lifestyle influences disease through plasma proteins. Applying HEAP to 2,686 proteins in 53,014 UK Biobank participants, we identified over 11,000 exposure-protein associations across 135 lifestyle exposures. Exposures explained a substantial portion of proteomic variation, with 9% of proteins more influenced by lifestyle than genetics. Mediation analyses across 270 diseases revealed proteins linking exposures to disease risk; for instance, IGFBP1 and IGFBP2 mediated the effects of exercise and diet on type 2 diabetes. These findings were supported by concordant proteomic shifts in interventional studies of exercise and GLP1 agonists, underscoring therapeutic relevance. HEAP provides a resource for advancing disease prevention and precision medicine by revealing mechanisms through which lifestyle shapes human health.

Identification of growth differentiation factor 15 as an early predictive biomarker for metabolic dysfunction-associated steatohepatitis: A nested case-control study of UK Biobank proteomic data

AIMS

This study aims to determine the predictive capability for metabolic dysfunction-associated steatohepatitis (MASH) long before its diagnosis by using six previously identified diagnostic biomarkers for metabolic dysfunction-associated steatotic liver disease (MASLD) with proteomic data from the UK Biobank.

MATERIALS AND METHODS

A nested case-control study comprising a MASH group and three age- and sex-matched control groups (metabolic dysfunction-associated steatosis, viral hepatitis and normal liver controls) was conducted. Olink proteomics, anthropometric and biochemical data at baseline levels were obtained from the UK Biobank. The baseline levels of CDCP1, FABP4, FGF21, GDF15, IL-6 and THBS2 were analysed prospectively to determine their predictive accuracy for subsequent diagnosis with a mean lag time of over 10 years.

RESULTS

At baseline, GDF15 demonstrated the best performance for predicting MASH occurrence at 5 and 10 years later, with AUCs of 0.90 at 5 years and 0.86 at 10 years. A predictive model based on four biomarkers (GDF15, FGF21, IL-6 and THBS2) showed AUCs of 0.88 at both 5 and 10 years. Furthermore, a protein-clinical model that included these four circulating protein biomarkers along with three clinical factors (BMI, ALT and TC) yielded AUCs of 0.92 at 5 years and 0.89 at 10 years.

CONCLUSIONS

GDF15 at baseline levels outperformed other individual circulating protein biomarkers for the early prediction of MASH. Our data suggest that GDF15 and the GDF15-based model may be used as easy-to-implement tools to identify patients with high risks of developing MASH at a mean lag time of over 10 years.

Repression of oxidative phosphorylation by NR2F2, MTERF3 and GDF15 in human skin under high-glucose stress

Lifestyle factors such as a Western diet or metabolic diseases like diabetes disrupt glucose homeostasis and induce stress responses, yet their impact on skin metabolism and structural integrity remains poorly understood. Here, we performed multiomic and bioenergetic analyses of human dermal fibroblasts (HDFs), human equivalent dermis (HED), human reconstructed skin (HRS), and skin explants from diabetic patients. We found that 12 mM glucose stress represses oxidative phosphorylation (OXPHOS) through a dual mechanism: the glucose-dependent nuclear receptor NR2F2 activates mitochondrial transcription termination factor 3 (MTERF3) while inhibiting growth-differentiation factor 15 (GDF15). Promoter assays revealed that MTERF3 is regulated by NR2F2 and MYCN, whereas GDF15 is modulated by NR2F2 and FOS. Consequently, OXPHOS proteins and mitochondrial respiration were suppressed, and MTERF3 overexpression additionally interfered with collagen biosynthesis. In contrast, GDF15 supplementation fully rescued hyperglycemia-induced bioenergetic and metabolomic alterations, suggesting a pharmacological strategy to mitigate hyperglycemic damage in the skin. Finally, silencing GDF15 or TFAM impaired fibroblast haptotaxis and skin reconstruction, underscoring the crucial role of mitochondrial energetics in dermal structure and function. Collectively, these findings identify the NR2F2-MTERF3-GDF15 axis as a key mediator of OXPHOS suppression and highlight a potential therapeutic target to preserve skin integrity under hyperglycemic stress.

Research progress on the mechanism and treatment of cachexia based on tumor microenvironment

Cachexia is a prevalent multifactorial syndrome characterized by a substantial decrease in food intake, which results from processes such as proteolysis, lipolysis, inflammatory activation, and autophagy, ultimately leading to weight loss. In cancer patients, this condition is referred to as cancer-related cachexia (CRC) and affects over 50% of this population. A comprehensive understanding of the intricate interactions between tumors and the host organism is essential for the development of effective treatments for tumor cachexia. This review aims to elucidate the role of the tumor microenvironment (TME) in the pathogenesis of tumor-associated cachexia and to summarize the current evidence supporting treatment modalities that target the TME.

GDF15 links adipose tissue lipolysis with anxiety

Psychological stress changes both behaviour and metabolism to protect organisms. Adrenaline is an important driver of this response. Anxiety correlates with circulating free fatty acid levels and can be alleviated by a peripherally restricted β-blocker, suggesting a peripheral signal linking metabolism with behaviour. Here we show that adrenaline, the β3 agonist CL316,243 and acute restraint stress induce growth differentiation factor 15 (GDF15) secretion in white adipose tissue of mice. Genetic inhibition of adipose triglyceride lipase or genetic deletion of β-adrenergic receptors blocks β-adrenergic-induced increases in GDF15. Increases in circulating GDF15 require lipolysis-induced free fatty acid stimulation of M2-like macrophages within white adipose tissue. Anxiety-like behaviour elicited by adrenaline or restraint stress is eliminated in mice lacking the GDF15 receptor GFRAL. These data provide molecular insights into the mechanisms linking metabolism and behaviour and suggest that inhibition of GDF15-GFRAL signalling might reduce acute anxiety.

Chemical Affinity Capture of Plasma Extracellular Vesicles Enables Efficient and Large-Scale Proteomic Identification of Prostate Cancer Biomarkers

The serum prostate-specific antigen (PSA) testing is widely used for prostate cancer (PCa) screening but suffers from poor specificity, leading to unnecessary biopsies and overtreatment. The significant potential of extracellular vesicles (EVs) in cancer diagnosis has driven the development of efficient methods to isolate and identify EV biomarkers from large-scale clinical samples. Here, we systematically evaluate five commonly used EV isolation techniques through proteomic profiling of plasma-derived EVs, endorsing TiO2-based chemical affinity capture as a superior approach for analyzing EVs from complex clinical samples. This method demonstrates exceptional advantages in speed, throughput, reproducibility, and protein coverage. Using this optimized workflow, we analyzed plasma EVs from 80 patients with PCa and benign prostatic hyperplasia (BPH), identifying growth differentiation factor 15 (GDF15) as a compelling biomarker with a predictive power (AUC) of 0.908 for PCa. Extensive validation across independent cohorts comprising 457 samples, including plasma EVs and prostate tissues, confirmed GDF15's ability to distinguish PCa from BPH and stratify PCa stages. Notably, the combination of GDF15 with PSA further enhanced diagnostic efficiency, particularly for patients in the PSA diagnostic gray zone. This study establishes a robust workflow for EV protein analysis in large clinical cohorts and highlights EV-GDF15 as a promising biomarker for noninvasive PCa diagnosis.

Association of Circulating GDF-15 with Fetal Growth in Gestational Diabetes

Background/Objectives: Growth differentiation factor-15 (GDF-15) is a component of the transforming growth factor beta (TGF-β) family that may act as regulator of inflammation. A possible protective role of GDF-15 against glucose alterations has been hypothesized. The aim of this pilot study was to evaluate the relationship between a circulating concentration of GDF-15 and metabolic/inflammatory parameters, as well as with adverse perinatal outcomes in patients with gestational diabetes mellitus (GDM). Methods: Twenty-four (n = 24) patients with GDM and n = 29 age-matched pregnant women with normal glucose tolerance (NGT) were recruited at the third trimester of gestation. Clinical and biochemical parameters were collected. Serum levels of GDF-15, small dense low density lipoprotein cholesterol (sdLDL), interleukin 6 (IL-6), a Soluble Urokinase Plasminogen Activator Receptor (su-PAR) were measured by an enzyme-linked immunosorbent assay kit. Fetal ultrasound parameters, maternal, delivery, and perinatal outcomes, were assessed. Results: Serum GDF-15 did not differ between GDM and NGT (p = 0.286). However, in linear regression analysis, a significant negative association was observed between GDF-15 and fetal weight percentile at the third trimester, only in patients with GDM (p = 0.013), even after adjustment for age and pre-pregnancy BMI (p = 0.029). GDF-15 positively associated with IL-6, adjusting for pre-pregnancy BMI (p = 0.047). Pregnant women with adverse perinatal outcomes had higher levels of GDF-15 (p = 0.043). In the regression model, higher levels of GDF-15 were associated with an increased likelihood of adverse perinatal outcomes after adjustment for age and pre-pregnancy BMI (p = 0.044). Conclusions: Besides its action as regulator of inflammation, GDF-15 might have a possible protective role against hyperglycemia-related excessive fetal growth in GDM. GDF-15 circulating levels might also be related to adverse perinatal outcomes.

Crystal structure of Isthmin-1 and reassessment of its functional role in pre-adipocyte signaling

Isthmin-1 (ISM1) is a recently described adipokine with insulin-like properties that can control hyperglycemia and liver steatosis. Additionally, ISM1 is proposed to play critical roles in patterning, angiogenesis, vascular permeability, and apoptosis. A key feature of ISM1 is its AMOP (adhesion-associated domain in MUC4 (Mucin-4) and other proteins) domain which is essential for many of its functions. However, the molecular details of AMOP domains remain elusive as there are no descriptions of their structure. Here we determined the crystal structure of ISM1 including its thrombospondin type I repeat (TSR) and AMOP domain. Interestingly, ISM1's AMOP domain exhibits a distinct fold with similarities to bacterial streptavidin. When comparing our structure to predicted structures of other AMOP domains, we observed that while the core streptavidin-like barrel is conserved, the surface helices and loops vary greatly. Thus, the AMOP domain fold allows for structural plasticity that may underpin its diverse functions. Furthermore, and contrary to prior studies, we show that highly purified ISM1 does not stimulate AKT phosphorylation on 3T3-F442A pre-adipocytes. Rather, we find that co-purifying growth factors are responsible for this activity. Together, our data reveal the structure and clarify functional studies of this enigmatic protein.

Comprehensive Evaluation of Frailty and Sarcopenia Markers to Predict Survival in Glioblastoma Patients

BACKGROUND

Glioblastoma (GBM) is the most common primary malignant brain tumour in adults. Patients with GBM are particularly susceptible to moderate-to-high frail. Frailty status has been associated with the outcome of many types of cancer, including GBM, although there is still little consensus regarding the specific criteria for assessing frailty status. This study aimed to determine the predictive significance of the modified frailty score (mFS) in GBM patients using haematological and sarcopenia indicators.

METHODS

Between January 2016 and September 2022, we enrolled 309 adult GBM patients. Data on demographics, haematological examination, and temporal muscle thickness (TMT) were collected and assessed. The prognostic relevance of the frailty parameters was established using Kaplan-Meier and Cox proportional model. The scoring systems were created by integrating these indicators. Variables with independent prognostic values were used to construct the nomograms. Nomogram accuracy was evaluated using the calibration curve, Harrell's concordance index (C-index), and time-dependent receiver operating characteristic curves. Clinical practicality was assessed using decision curve analysis.

RESULTS

The baseline characteristics of the 309 participants revealed a median age of 59 years (interquartile range 52-66) with a predominance of male patients (58.58%). TMT (hazard ratio [HR] = 3.787, 95% confidence interval [CI] 2.576-5.566, p < 0.001), prognostic nutritional index (HR = 1.722, 95% CI 1.098-2.703, p = 0.018), and mean corpuscular volume (HR = 1.958, 95% CI 1.111-3.451, p = 0.020) were identified as independent prognostic markers. The constructed mFS, obtained by integrating these three indices, exhibited independent prognostic significance (HR = 2.461, 95% CI 1.751-3.457, p < 0.001). The patients in the low-risk group had a median overall survival (OS) of 13.9 months, while the patients in the high risk had a median OS of 5.8 months. Importantly, the mFS demonstrated significant independent prognostic value in the subgroup aged > 65 (HR = 1.822, 95% CI 1.011-3.284, p = 0.046). The nomogram, which included the mFS, demonstrated high accuracy, with a c-index of 0.781. The nomogram bootstrapped calibration plot also performed well compared to the ideal model. Nomograms showed promising discriminative potential, with time-dependent areas under the curves of 0.945, 0.835, and 0.820 for 0.5-, 1-, and 2-year overall survival prediction, respectively.

CONCLUSIONS

Preoperative mFS is a comprehensive frailty marker for predicting survival outcomes in patients with GBM. A dynamic nomogram incorporating the mFS may facilitate preoperative survival evaluation. Early and appropriate multimodal interventions, including nutritional support, rehabilitation, and psychological care, may help in the neurosurgical care of patients with GBM or other brain tumours.

Targeting senescent hepatocytes for treatment of metabolic dysfunction-associated steatotic liver disease and multi-organ dysfunction

Senescent hepatocytes accumulate in metabolic dysfunction-associated steatotic liver disease (MASLD) and are linked to worse clinical outcomes. However, their heterogeneity and lack of specific markers have made them difficult to target therapeutically. Here, we define a senescent hepatocyte gene signature (SHGS) using in vitro and in vivo models and show that it tracks with MASLD progression/regression across mouse models and large human cohorts. Single-nucleus RNA-sequencing and functional studies reveal that SHGS+ hepatocytes originate from p21+ cells, lose key liver functions and release factors that drive disease progression. One such factor, GDF15, increases in circulation alongside SHGS+ burden and disease progression. Through chemical screening, we identify senolytics that selectively eliminate SHGS+ hepatocytes and improve MASLD in male mice. Notably, SHGS enrichment also correlates with dysfunction in other organs. These findings establish SHGS+ hepatocytes as key drivers of MASLD and highlight a potential therapeutic strategy for targeting senescent cells in liver disease and beyond.

Current Prognostic Biomarkers for Peripheral Arterial Disease: A Comprehensive Systematic Review of the Literature

Background: Peripheral arterial disease (PAD) is a chronic atherosclerotic disease characterized by atheromatous plaque buildup within arteries of the lower limbs. It can lead to claudication, skin ulcerations, and, in severe cases, chronic limb-threatening ischemia, requiring amputation. There are several plasma protein biomarkers that have been suggested as prognostic markers for adverse events, including major adverse cardiovascular and limb events. However, the clinical benefit and ability to clinically adapt these biomarkers remains uncertain due to inconsistent findings possibly related to heterogenous study designs and differences in methodology. Objectives: This review aims to evaluate the current literature on the prognostic value of plasma protein biomarkers for PAD, their predictive ability for PAD-related adverse outcomes, and their potential roles in guiding PAD management. Methods: To address these challenges, we conducted a systematic review of MEDLINE, Embase, and Cochrane CENTRAL libraries of the current literature (2010-2024). Results: We found 55 studies that evaluated the prognostic value of 44 distinct plasma proteins across various pathophysiological processes. These included markers of immunity and inflammation, markers of metabolism, cardiac biomarkers, markers of kidney function, growth factors and hormones, markers of coagulation and platelet function, extracellular matrix and tissue remodeling proteins, and transport proteins. This review summarizes the existing evidence for prognostic protein plasma biomarkers for PAD and their association with adverse events related to PAD. Conclusions: With this review, we hope to provide a comprehensive list of the prognostic markers and their value as prognostic biomarkers to guide clinical decision making in these patients.

Comparative Analyses Between Vulnerability Biomarkers of Aging and Health Biomarkers in Middle-Aged and Older Female Adults

Biological aging is normally associated with greater physiological changes which predispose individuals to adverse outcomes. In this way, the evaluation of vulnerability biomarkers and their relationships with other health biomarkers could contribute to the promotion of interventions and the improvement of older adults' quality of life. Thereby, this study aimed to compare vulnerability biomarkers (Growth Differentiation Factor 15 (GDF-15), General Functional Fitness Index (GFFI), and frailty phenotype) and their influence on health markers (blood biochemistry, body composition, and hemodynamic variables) in middle-aged and older female adults. Methods: A cross-sectional observational study was conducted with community-dwelling females aged 54-84 with at least 6 months of experience with physical training. The participants were categorized based on functional fitness, frailty phenotype, and GDF-15 quartiles. The General Functional Fitness Index (GFFI) was assessed using the AAHPERD test battery, while frailty phenotype was determined using Fried's criteria. GDF-15 levels were measured through ELISA. Results: A higher training status (TS) showed better functional fitness and favorable biochemical profiles, including lower total cholesterol (p = 0.006, η2p = 0.253), LDL cholesterol (p = 0.001, η2p = 0.346), triglycerides (p = 0.048, η2p = 0.195), and systolic blood pressure (p = 0.001, η2p = 0.333). Individuals classified as robust (non-frail) had better physical performance and lower total cholesterol (p = 0.002, η2p = 0.306) and LDL cholesterol (p = 0.014, η2p = 0.216) compared to those classified as frail and pre-frail. The GDF-15 quartile did not present differences in health markers between groups. Conclusions: These findings suggest that GFFI may be considered a health biomarker for middle-aged and female older adults while highlighting the need for further research on the role of biomarkers of vulnerability and healthy aging.

Insomnia accelerates the epigenetic clocks in older adults

Insomnia is a common sleep disorder characterized mainly by poor sleep quality and insufficient sleep duration. It affects a significant proportion of the global population and is correlated with physical and mental consequences such as cognitive decline, anxiety, chronic fatigue, poor concentration, and memory impairment. Interestingly, it is also linked to ageing and age-related diseases (cardiovascular, metabolic, and neurodegenerative). On the other hand, as we age, DNA methylation patterns undergo significant changes. These have been used to develop the so-called epigenetic clocks that estimate the biological age linked to the environment and the risk of diseases. Few studies have evaluated the association between insomnia and epigenetic clocks, providing insight into the role of insomnia in ageing acceleration. Therefore, in the present study, we carried out an epigenetic analysis by using Illumina EPICv.2 array on 63 older adults (> 60 years old, n = 33 with insomnia vs. n = 30 control) to evaluate the relation between insomnia and epigenetic ages (HorvathAGE, HannumAGE, PhenoAGE, SkinBloodClock, GrimAGE, DunedinPACE, DNAmTL). As a result, we found an increased acceleration and correlation between GrimAGE and SkinBloodClock and a significant reduction in the DNAmTL in individuals with insomnia. An EWAS analysis showed a global pattern of hypomethylation and an enrichment of several proteostasis and oxidative pathways. In conclusion, our results suggest that insomnia increases GrimAGE and SkinBloodClock acceleration and may be participating in telomere shortening. Additionally, changes in DNA methylation patterns induced by insomnia impact proteostasis and oxidative stress.

Genetically supported targets and drug repurposing for brain aging: A systematic study in the UK Biobank

Brain age gap (BAG), the deviation between estimated brain age and chronological age, is a promising marker of brain health. However, the genetic architecture and reliable targets for brain aging remains poorly understood. In this study, we estimate magnetic resonance imaging (MRI)-based brain age using deep learning models trained on the UK Biobank and validated with three external datasets. A genome-wide association study for BAG identified two unreported loci and seven previously reported loci. By integrating Mendelian Randomization (MR) and colocalization analysis on eQTL and pQTL data, we prioritized seven genetically supported druggable genes, including MAPT, TNFSF12, GZMB, SIRPB1, GNLY, NMB, and C1RL, as promising targets for brain aging. We rediscovered 13 potential drugs with evidence from clinical trials of aging and prioritized several drugs with strong genetic support. Our study provides insights into the genetic basis of brain aging, potentially facilitating drug development for brain aging to extend the health span.

Mitochondrial damage in muscle specific PolG mutant mice activates the integrated stress response and disrupts the mitochondrial folate cycle

During mitochondrial damage, information is relayed between the mitochondria and nucleus to coordinate precise responses to preserve cellular health. One such pathway is the mitochondrial integrated stress response (mtISR), which is known to be activated by mitochondrial DNA (mtDNA) damage. However, the causal molecular signals responsible for activation of the mtISR remain mostly unknown. A gene often associated with mtDNA mutations/deletions is Polg1, which encodes the mitochondrial DNA Polymerase γ (PolG). Here, we describe an inducible, tissue specific model of PolG mutation, which in muscle specific animals leads to rapid development of mitochondrial dysfunction and muscular degeneration in male animals from ~5 months of age. Detailed molecular profiling demonstrated robust activation of the mtISR in muscles from these animals. This was accompanied by striking alterations to enzymes in the mitochondrial folate cycle that was likely driven by a specific depletion in the folate cycle metabolite 5,10 methenyl-THF, strongly implying imbalanced folate intermediates as a previously unrecognised pathology linking the mtISR and mitochondrial disease.

Skeletal muscle mitochondrial dysfunction is associated with increased Gdf15 expression and circulating GDF15 levels in aged mice

Growth differentiation factor-15 (GDF15) is a biomarker of multiple disease states and circulating GDF15 levels are increased during aging in both pre-clinical animal models and human studies. Accordingly, multiple stressors have been identified, including mitochondrial dysfunction, that lead to induction of Gdf15 expression downstream of the integrated stress response (ISR). For some disease states, the source of increased circulating GDF15 is evident based on the specific pathology. Aging, however, presents a less tractable system for understanding the source of increased plasma GDF15 levels in that cellular dysfunction with aging can be pleiotropic and heterogeneous. To better understand which organ or organs contribute to increased circulating GDF15 levels with age, and whether changes in metabolic and mitochondrial dysfunction were associated with these potential changes, we compared young 12-week-old and middle-aged 52-week-old C57BL/6 J mice using a series of metabolic phenotyping studies and by comparing circulating levels of GDF15 and tissue-specific patterns of Gdf15 expression. Overall, we found that Gdf15 expression was increased in skeletal muscle but not liver, white or brown adipose tissue, kidney or heart of middle-aged mice, and that insulin sensitivity and mitochondrial respiratory capacity were impaired in middle-aged mice. These data suggest that early changes in skeletal muscle mitochondrial function and metabolism contribute to increased circulating GDF15 levels observed during aging.

Growth and differentiation factor 15: An emerging therapeutic target for brain diseases

Growth and differentiation factor 15 (GDF15), a member of the transforming growth factor-βsuperfamily, is considered a stress response factor and has garnered increasing attention in recent years due to its roles in neurological diseases. Although many studies have suggested that GDF15 expression is elevated in patients with neurodegenerative diseases (NDDs), glioma, and ischemic stroke, the effects of increased GDF15 expression and the potential underlying mechanisms remain unclear. Notably, many experimental studies have shown the multidimensional beneficial effects of GDF15 on NDDs, and GDF15 overexpression is able to rescue NDD-associated pathological changes and phenotypes. In glioma, GDF15 exerts opposite effects, it is both protumorigenic and antitumorigenic. The causes of these conflicting findings are not comprehensively clear, but inhibiting GDF15 is helpful for suppressing tumor progression. GDF15 is also regarded as a biomarker of poor clinical outcomes in ischemic stroke patients, and targeting GDF15 may help prevent this disease. Thus, we systematically reviewed the synthesis, transcriptional regulation, and biological functions of GDF15 and its related signaling pathways within the brain. Furthermore, we explored the potential of GDF15 as a therapeutic target and assessed its clinical applicability in interventions for brain diseases. By integrating the latest research findings, this study provides new insights into the future treatment of neurological diseases.

Identifying proteins and pathways associated with multimorbidity in 53,026 adults

BACKGROUND AND AIMS

Multimorbidity, the coexistence of multiple chronic diseases, is a rapidly expanding global health challenge, carrying profound implications for patients, caregivers, healthcare systems, and society. Investigating the determinants and drivers underlying multiple chronic diseases is a priority for disease management and prevention.

METHOD

This prospective cohort study analyzed data from the 53,026 participants in the UK Biobank from baseline (2006 to 2010) across 13.3 years of follow-up. Using Cox proportional hazards regression model, we characterized shared and unique associations across 38 incident outcomes (31 chronic diseases, 6 system mortality and all-cause mortality). Furthermore, ordinal regression models were used to assess the association between protein levels and multimorbidity (0-1, 2, 3-4, or ≥ 5 chronic diseases). Functional and tissue enrichment analysis were employed for multimorbidity-associated proteins. The upstream regulators of above proteins were identified.

RESULTS

We demonstrated 972 (33.3 %) proteins were shared across at least two incident chronic diseases after Bonferroni correction (P < 3.42 × 10-7, 93.3 % of those had consistent effects directions), while 345 (11.8 %) proteins were uniquely linked to a single chronic disease. Remarkably, GDF15, PLAUR, WFDC2 and AREG were positively associated with 20-24 incident chronic diseases (hazards ratios: 1.21-3.77) and showed strong associations with multimorbidity (odds ratios: 1.33-1.89). We further identified that protein levels are explained by common risk factors, especially renal function, liver function, inflammation, and obesity, providing potential intervention targets. Pathway analysis has underscored the pivotal role of the immune response, with the top three transcription factors associated with proteomics being NFKB1, JUN and RELA.

CONCLUSIONS

Our results enhance the understanding of the biological basis underlying multimorbidity, offering biomarkers for disease identification and novel targets for therapeutic intervention.

Plasma proteomic signatures of social isolation and loneliness associated with morbidity and mortality

The biology underlying the connection between social relationships and health is largely unknown. Here, leveraging data from 42,062 participants across 2,920 plasma proteins in the UK Biobank, we characterized the proteomic signatures of social isolation and loneliness through proteome-wide association study and protein co-expression network analysis. Proteins linked to these constructs were implicated in inflammation, antiviral responses and complement systems. More than half of these proteins were prospectively linked to cardiovascular disease, type 2 diabetes, stroke and mortality during a 14 year follow-up. Moreover, Mendelian randomization (MR) analysis suggested causal relationships from loneliness to five proteins, with two proteins (ADM and ASGR1) further supported by colocalization. These MR-identified proteins (GFRA1, ADM, FABP4, TNFRSF10A and ASGR1) exhibited broad associations with other blood biomarkers, as well as volumes in brain regions involved in interoception and emotional and social processes. Finally, the MR-identified proteins partly mediated the relationship between loneliness and cardiovascular diseases, stroke and mortality. The exploration of the peripheral physiology through which social relationships influence morbidity and mortality is timely and has potential implications for public health.

Senescent alveolar type II epithelial cells-secreted GDF15 promotes silicosis progression via interfering intercellular communication

BACKGROUND

Silicosis is a chronic fibrotic pulmonary disease caused by consistent inhalation of respirable crystalline-free silica dust. The senescence of alveolar epithelial type II cells (ATII) is considered the initiation of pulmonary fibrosis. As a secreted protein, growth differentiation factor 15 (GDF15) was found intimately associated with the severity of lung diseases via senescence. Therefore, we speculate that GDF15 may involved in silica-induced pulmonary fibrosis.

METHODS

Co-culture was performed to observe the pro-fibrotic effect of GDF15, which is secreted from the silica-induced senescence ATII cells, on peripheral effector cells. We further explored GDF15-related signaling pathways via ChIP and IP assays. GDF15 siRNA lipid nanoparticles, anti-aging compound β-nicotinamide mononucleotide (NMN), and the Chinese traditional drug Bazibushen (BZBS) were used individually to intervene silicosis progress.

RESULTS

SiO2 and etoposide-stimulated MLE-12 cells showed senescence phenotype and secreted substantial GDF15, which is consistent with over-expressed GDF15 in lung tissues from silica-induced pulmonary fibrosis. The results further demonstrated that senescence ATII cells could facilitate co-cultured epithelial cell epithelial-mesenchymal transition (EMT) and fibroblast activation in a GDF15-dependent manner. Mechanistically, p53 regulates GDF15 transcription and secretion in senescence ATII cells. Moreover, secreted GFD15 performed its pro-fibrotic role by directly binding to TGF-βR via autocrine and paracrine manners. Also, lipid nanoparticles targeting GDF15 or cell senescence inhibitor NMN and BZBS showed efficient anti-fibrotic effects in vivo.

CONCLUSIONS

Our results elucidate that senescence ATII cell-secreted GDF15 plays a vital role in promoting silicosis by influencing surrounding cells, and provides scientific clues for the selection of potential therapeutic drugs for silicosis.

GDF15 inhibits early-stage adipocyte differentiation by enhancing HOP2 expression and suppressing C/EBPα expression

Excessive adipocyte differentiation and accumulation contribute to the development of metabolic disorders. Growth differentiation factor 15 (GDF15) plays an essential role in energy homeostasis and is considered an anti-obesity factor; however, elevated serum levels of endogenous GDF15 have been reported in certain individuals with obesity. In this study, to gain a better understanding of this complex relationship between GDF15 levels and obesity, we investigated GDF15 expression and function during adipogenesis. Compared with mice fed a normal diet, those fed a short-term high-fat diet exhibited a reduction in epididymal white adipose tissue and serum GDF15 expression. These results were confirmed in human adipose-derived stem cells that showed reduced GDF15 expression during adipogenesis differentiation. During adipogenesis, GDF15 was primarily degraded via the autophagy lysosomal pathway, and GDF15 overexpression in pre-adipocytes inhibited adipogenesis by suppressing CCAAT enhancer binding protein alpha (C/EBPα). Furthermore, whereas we detected a reduction in homologous-pairing protein 2 (HOP2) expression during adipogenesis, expression increased in response to an overexpression of GDF15. Furthermore, following knockdown of HOP2 during GDF15 overexpression, there was no suppression of C/EBPα expression. These findings indicate that GDF15 undergoes lysosomal degradation via an autophagic pathway and suppresses adipocyte differentiation via the HOP2-mediated inhibition of C/EBPα expression. Collectively, our findings indicate that GDF15 could serve as a potential therapeutic target for the treatment of metabolic disorders.

Skeletal muscle growth to combat diabetes and obesity: the potential role of muscle-secreted factors

As the prevalence of obesity and metabolic disease continues to climb, the need for effective therapeutic interventions remains high. The growth of skeletal muscle (SkM) greatly influences systemic metabolism across the whole body, making this tissue an important therapeutic target to combat the rise of metabolic dysfunction. Transgenic rodent models of targeted SkM growth exhibit profound improvements in various remote tissues, including adipose tissue and the liver. It is currently unclear how selective stimulation of SkM growth alters the metabolism of distant tissues; however, evidence suggests that muscle-secreted factors may be involved. Here, we aim to provide basic biomedical researchers with a summary of the current knowledge regarding various muscle-secreted factors regulated by anabolic pathways and proteins in SkM, as well as their systemic metabolic effects, to implicate them in the whole-body metabolic effects of SkM growth. In this review, we also identify several knowledge gaps in this field, future directions of investigation, and implications for therapeutic interventions such as resistance exercise and pharmacology.

Magnolol inhibits appetite and causes visceral fat loss through Growth/differentiation factor-15 (GDF-15) by activating transcription factor 4-CCAAT enhancer binding protein γ-mediated endoplasmic reticulum stress responses

Magnolol, a compound extracted from Magnolia officinalis, demonstrates potential efficacy in addressing metabolic dysfunction and cardiovascular diseases. Its biological activities encompass anti-inflammatory, antioxidant, anticoagulant, and anti-diabetic effects. Growth/differentiation factor-15 (GDF-15), a member of the transforming growth factor β superfamily, is considered a potential therapeutic target for metabolic disorders. This study investigated the impact of magnolol on GDF-15 production and its underlying mechanism. The research examined the pharmacological effect of magnolol on GDF-15 expression in vitro and in vivo, and determined the involvement of endoplasmic reticulum (ER) stress signaling in this process. Luciferase reporter assays, chromatin immunoprecipitation, and in vitro DNA binding assays were employed to examine the regulation of GDF-15 by activating transcription factor 4 (ATF4), CCAAT enhancer binding protein γ (CEBPG), and CCCTC-binding factor (CTCF). The study also investigated the effect of magnolol and ATF4 on the activity of a putative enhancer located in the intron of the GDF-15 gene, as well as the influence of single nucleotide polymorphisms (SNPs) on magnolol and ATF4-induced transcription activity. Results demonstrated that magnolol triggers GDF-15 production in endothelial cells (ECs), hepatoma cell line G2 (HepG2) and hepatoma cell line 3B (Hep3B) cell lines, and primary mouse hepatocytes. The cooperative binding of ATF4 and CEBPG upstream of the GDF-15 gene or the E1944285 enhancer located in the intron led to full-power transcription of the GDF-15 gene. SNP alleles were found to impact the magnolol and ATF4-induced transcription activity of GDF-15. In high-fat diet ApoE-/- mice, administration of magnolol induced GDF-15 production and partially suppressed appetite through GDF-15. These findings suggest that magnolol regulates GDF-15 expression through priming of promoter and enhancer activity, indicating its potential as a drug for the treatment of metabolic disorders.

Targeting GDF15 to enhance immunotherapy efficacy in glioblastoma through tumor microenvironment-responsive CRISPR-Cas9 nanoparticles

Despite the outstanding clinical success of immunotherapy, its therapeutic efficacy in glioblastoma (GBM) is still limited. To identify critical regulators of GBM immunity, we constructed a mouse single-guide RNA (sgRNA) library corresponding to all disease-related immune genes, and performed an in vivo CRISPR knockout (KO) screen in syngeneic GBM mouse models. We demonstrated that the deletion of GDF15 in GBM cells ameliorated the immunosuppressive tumor microenvironment (TME) and enhanced the antitumor efficacy of immune checkpoint blockade (ICB) response. Moreover, we designed unique nanoparticles for efficient encapsulation of CRISPR-Cas9, noninvasive brain delivery and tumor cell targeting, demonstrating an effective and safe strategy for GDF15 gene therapy. The CRISPR-Cas9 nanoparticles, known as ANPSS (Cas9/sgRNA), are easily created by enclosing a single Cas9/sgRNA complex in a polymer shell that is sensitive to glutathione. This shell also contains a dual-action ligand that aids in crossing the blood‒brain barrier, targeting tumor cells, and selectively releasing Cas9/sgRNA. Our encapsulating nanoparticles demonstrated promising GBM targeting, resulting in high GDF15 gene editing efficiency within brain tumors while showing minimal off-target gene editing in high-risk tissues. Treatment with ANPSS (Cas9/sgGDF15) effectively halted tumor growth, reversed immune suppression, and enhanced the efficacy of ICB therapy. These results emphasize the potential role of GDF15 in modulating the immune microenvironment and enhancing the effectiveness of current immunotherapy strategies for GBM.

A Growth Differentiation Factor 15 Receptor Agonist in Randomized Placebo-Controlled Trials in Healthy or Obese Persons

BACKGROUND

Growth differentiation factor 15 (GDF15), a divergent member of the TGF-β superfamily, signals via the hindbrain glial-derived neurotrophic factor receptor alpha-like and rearranged during transfection receptor co-receptor (GFRAL-RET) complex. In nonclinical species, GDF15 is a potent anorexigen leading to substantial weight loss. MBL949 is a half-life extended recombinant human GDF15 dimer.

METHODS

MBL949 was evaluated in multiple nonclinical species, and then in humans, in 2 randomized and placebo-controlled clinical trials. In the phase 1, first-in-human, single ascending dose trial, MBL949 or placebo was injected subcutaneously to overweight and obese healthy volunteers (n = 65) at doses ranging from 0.03 to 20 mg. In phase 2, MBL949 or placebo was administered subcutaneously every other week for a total of 8 doses to obese participants (n = 126) in 5 different dose regimens predicted to be efficacious based on data from the phase 1 trial.

RESULTS

In nonclinical species, MBL949 was generally safe and effective with reduced food intake and body weight in mice, rats, dogs, and monkeys. Weight loss was primarily from reduced fat, and metabolic endpoints improved. A single ascending dose study in overweight or obese healthy adults demonstrated mean terminal half-life of 18 to 22 days and evidence of weight loss at the higher doses. In the phase 2, weight loss was minimal following biweekly dosing of MBL949 for 14 weeks. MBL949 was safe and generally tolerated in humans over the dose range tested, adverse events of the gastrointestinal system were the most frequent observed.

CONCLUSION

The prolonged half-life of MBL949 supports biweekly dosing in patients. MBL949 had an acceptable safety profile. The robust weight loss observed in nonclinical species did not translate to weight loss efficacy in humans.

Berberine-induced browning and energy metabolism: mechanisms and implications

Obesity has become a global pandemic. The approaches researched to prevent it include decreasing energy intake and/or enhancing energy expenditure. Therefore, research on brown adipose tissue is of great importance. Brown adipose tissue is characterized by its high mitochondrial content. Mitochondrial uncoupling protein 1 (UCP1) releases energy as heat instead of chemical energy. Thermogenesis increases energy expenditure. Berberine, a phytochemical widely used in Asian countries, has positive effects on body weight control. While the precise mechanisms behind this effect remain unclear, the adenosine monophosphate-activated protein kinase (AMPK) pathway is known to play a crucial role. Berberine activates AMPK through phosphorylation, significantly impacting brown adipose tissue by enhancing lipolytic activity and increasing the expression of UCP1, peroxisome proliferator-activated receptor γ-co-activator-1α (PGC1α), and PR domain containing 16 (PRDM16). While investigating the mechanism of action of berberine, both the AMPK pathway is being examined in more detail and alternative pathways are being explored. One such pathway is growth differentiation factor 15 (GDF15), known for its appetite-suppressing effect. Berberine's low stability and bioavailability, which are the main obstacles to its clinical use, have been improved through the development of nanotechnological methods. This review examines the potential mechanisms of berberine on browning and summarizes the methods developed to enhance its effect.

Exploring the Effects of Metformin on the Body via the Urine Proteome

Metformin is the first-line medication for treating type 2 diabetes mellitus, with more than 200 million patients taking it daily. Its effects are extensive and play a positive role in multiple areas. Can its effects and potential mechanisms be explored through the urine proteome? In this study, 166 differential proteins were identified following the administration of 150 mg/(kg·d) of metformin to rats for five consecutive days. These included complement component C6, pyruvate kinase, coagulation factor X, growth differentiation factor 15, carboxypeptidase A4, chymotrypsin-like elastase family member 1, and L-lactate dehydrogenase C chain. Several of these proteins have been reported to be directly affected by metformin or associated with its effects. Multiple biological pathways enriched by these differential proteins, or proteins containing differentially modified peptides, have been reported to be associated with metformin, such as the glutathione metabolic process, negative regulation of gluconeogenesis, and the renin-angiotensin system. Additionally, some significantly changed proteins and enriched biological pathways, not yet reported to be associated with metformin's effects, may provide clues for exploring its potential mechanisms. In conclusion, the application of the urine proteome offers a comprehensive and systematic approach to exploring the effects of drugs, providing a new perspective on the study of metformin's mechanisms.

GDF15 Neutralization Ameliorates Muscle Atrophy and Exercise Intolerance in a Mouse Model of Mitochondrial Myopathy

BACKGROUND

Primary mitochondrial myopathies (PMMs) are disorders caused by mutations in genes encoding mitochondrial proteins and proteins involved in mitochondrial function. PMMs are characterized by loss of muscle mass and strength as well as impaired exercise capacity. Growth/Differentiation Factor 15 (GDF15) was reported to be highly elevated in PMMs and cancer cachexia. Previous studies have shown that GDF15 neutralization is effective in improving skeletal muscle mass and function in cancer cachexia. It remains to be determined if the inhibition of GDF15 could be beneficial for PMMs. The purpose of the present study is to assess whether treatment with a GDF15 neutralizing antibody can alleviate muscle atrophy and physical performance impairment in a mouse model of PMM.

METHODS

The effects of GDF15 neutralization on PMM were assessed using PolgD257A/D257A (POLG) mice. These mice express a proofreading-deficient version of the mitochondrial DNA polymerase gamma, leading to an increased rate of mutations in mitochondrial DNA (mtDNA). These animals display increased circulating GDF15 levels, reduced muscle mass and function, exercise intolerance, and premature aging. Starting at 9 months of age, the mice were treated with an anti-GDF15 antibody (mAB2) once per week for 12 weeks. Body weight, food intake, body composition, and muscle mass were assessed. Muscle function and exercise capacity were evaluated using in vivo concentric max force stimulation assays, forced treadmill running and voluntary home-cage wheel running. Mechanistic investigations were performed via muscle histology, bulk transcriptomic analysis, RT-qPCR and western blotting.

RESULTS

Anti-GDF15 antibody treatment ameliorated the metabolic phenotypes of the POLG animals, improving body weight (+13% ± 8%, p < 0.0001), lean mass (+13% ± 15%, p < 0.001) and muscle mass (+35% ± 24%, p < 0.001). Additionally, the treatment improved skeletal muscle max force production (+35% ± 43%, p < 0.001) and exercise performance, including treadmill (+40% ± 29%, p < 0.05) and voluntary wheel running (+320% ± 19%, p < 0.05). Mechanistically, the beneficial effects of GDF15 neutralization are linked to the reversal of the transcriptional dysregulation in genes involved in autophagy and proteasome signalling. The treatment also appears to dampen glucocorticoid signalling by suppressing circulating corticosterone levels in the POLG animals.

CONCLUSIONS

Our findings highlight the potential of GDF15 neutralization with a monoclonal antibody as a therapeutic avenue to enhance physical performance and mitigate adverse clinical outcomes in patients with PMM.

Neural pathways of nausea and roles in energy balance

Our internal sensory systems encode various gut-related sensations, such as hunger, feelings of fullness, and nausea. These internal feelings influence our eating behaviors and play a vital role in regulating energy balance. Among them, the neurological basis for nausea has been the least well characterized, which has hindered comprehension of the connection between these sensations. Single-cell sequencing, along with functional mapping, has brought clarity to the neural pathways of nausea involving the brainstem area postrema. In addition, the newly discovered nausea sensory signals have deepened our understanding of the area postrema in regulating feeding behaviors. Nausea has significant clinical implications, especially in developing drugs for weight loss and metabolism. This review summarizes recent research on the neural pathways of nausea, particularly highlighting their contribution to energy balance.

The metabolic basis of cancer-related fatigue

Although we are all familiar with the sensation of fatigue, there are still profound divergences on what it represents and its mechanisms. Fatigue can take various forms depending on the condition in which it develops. Cancer-related fatigue is considered a symptom of exhaustion that is often present at the time of diagnosis, increases in intensity during cancer therapy, and does not always recede after completion of treatment. It is usually attributed to the inflammation induced by damage-associated molecular patterns released by tumor cells during cancer progression and in response to its treatment. In this review, we argue that it is necessary to go beyond the symptoms of fatigue to understand its nature and mechanisms. We propose to consider fatigue as a psychobiological process that regulates the behavioral activities an organism engages in to satisfy its needs, according to its physical ability to do so and to the capacity of its intermediary metabolism to exploit the resources procured by these activities. This last aspect is critical as it implies that these metabolic aspects need to be considered to understand fatigue. Based on the findings we have accumulated over several years of studying fatigue in diverse murine models of cancer, we show that energy metabolism plays a key role in the development and persistence of this condition. Cancer-related fatigue is dependent on the energy requirements of the tumor and the negative impact of cancer therapy on the mitochondrial function of the host. When inflammation is present, it adds to the organism's energy expenses. The organism needs to adjust its metabolism to the different forms of cellular stress it experiences thanks to specialized communication factors known as mitokines that act locally and at a distance from the cells in which they are produced. They induce the subjective, behavioral, and metabolic components of fatigue by acting in the brain. Therefore, the targeting of mitokines and their brain receptors offers a window of opportunity to treat fatigue when it is no longer adaptive but an obstacle to the quality of life of cancer survivors.

Alterations in the proteomes of HepG2 and IHKE cells inflicted by six selected mycotoxins

Toxic fungal secondary metabolites, referred to as mycotoxins, emerge in moldy food and feed and constitute a potent but often underestimated health threat for humans and animals. They are structurally diverse and can cause diseases after dietary intake even in low concentrations. To elucidate cellular responses and identify cellular targets of mycotoxins, a bottom-up proteomics approach was used. We investigated the effects of the mycotoxins aflatoxin B1, ochratoxin A, citrinin, deoxynivalenol, nivalenol and penitrem A on the human hepatoblastoma cell line HepG2 and of ochratoxin A and citrinin on the human kidney epithelial cell line IHKE. Incubations were carried out at sub-cytotoxic concentrations to monitor molecular effects before acute cell death mechanisms predominate. Through these experiments, we were able to detect specific cellular responses that point towards the mycotoxins' mode of action. Besides very well-described mechanisms like the ribotoxicity of the trichothecenes, we observed not yet described effects on different cellular mechanisms. For instance, trichothecenes lowered the apolipoprotein abundance and aflatoxin B1 affected proteins related to inflammation, ribogenesis and mitosis. Ochratoxin A and citrinin upregulated the minichromosomal maintenance complex and nucleotide synthesis in HepG2 and downregulated histones in IHKE. Penitrem A reduced enzyme levels of the sterol biosynthesis. These results will aid in the elucidation of the toxicodynamic properties of this highly relevant class of toxins.

Senescence of endothelial cells promotes phenotypic changes in adventitial fibroblasts: possible implications for vascular aging

Aging is the most important risk factor for the development of cardiovascular diseases. Senescent cells release plethora of factors commonly known as the senescence-associated secretory phenotype, which can modulate the normal function of the vascular wall. It is currently not well understood if and how endothelial cell senescence can affect adventitial niche. The aim of this study was to characterize oxidative stress-induced endothelial cells senescence and identify their paracrine effects on the primary cell type of the adventitia, the fibroblasts. Human aortic endothelial cells (HAEC) were treated with hydrogen peroxide to induce premature senescence. Mass spectrometry analysis identified several proteomic changes in senescent HAEC with top upregulated secretory protein growth differentiation factor 15 (GDF-15). Treatment of the human adventitial fibroblast cell line (hAdv cells) with conditioned medium (CM) from senescent HAEC resulted in alterations in the proteome of hAdv cells identified in mass spectrometry analysis. Majority of differentially expressed proteins in hAdv cells treated with CM from senescent HAEC were involved in the uptake and metabolism of lipoproteins, mitophagy and ferroptosis. We next analyzed if some of these changes and pathways might be regulated by GDF-15. We found that recombinant GDF-15 affected some ferroptosis-related factors (e.g. ferritin) and decreased oxidative stress in the analyzed adventitial fibroblast cell line, but it had no effect on erastin-induced cell death. Contrary, silencing of GDF-15 in hAdv cells was protective against this ferroptotic stimuli. Our findings can be of importance for potential therapeutic strategies targeting cell senescence or ferroptosis to alleviate vascular diseases.

Associations between prenatal distress, mitochondrial health, and gestational age: findings from two pregnancy studies in the USA and Turkey

Objective

This study examined associations between mitochondrial markers-circulating cell-free mitochondrial DNA (cf-mtDNA) and Growth Differentiation Factor-15 (GDF15)-with maternal distress and pregnancy outcomes.

Method

Participants were drawn from two pregnancy studies, EPI (N=187, USA) and BABIP (N=198, Turkey). Plasma cf-mtDNA and GDF15 levels were quantified using qPCR and ELISA assays.

Results

Plasma cf-mtDNA levels did not significantly vary across pregnancy, while plasma GDF15 levels increased from early to late pregnancy and decreased postpartum. Late 2nd trimester plasma GDF15 was negatively correlated with pre-pregnancy BMI (p=0.035) and gestational age (p=0.0048) at birth. Early 2nd trimester maternal distress was associated with lower cf-mtDNA (p<0.05) and a trend for lower GDF15. Higher pre-pregnancy BMI and late-pregnancy maternal distress were linked to smaller postpartum GDF15 declines in EPI (p<0.05).

Conclusion

This study reveals distinct plasma cf-mtDNA and GDF15 patterns during the perinatal period, linking mitochondrial markers to maternal distress and pregnancy outcomes.

GDF15-mediated enhancement of the Warburg effect sustains multiple myeloma growth via TGFβ signaling pathway

The Warburg effect, characterized by the shift toward aerobic glycolysis, is closely associated with the onset and advancement of tumors, including multiple myeloma (MM). Nevertheless, the specific regulatory mechanisms of glycolysis in MM and its functional role remain unclear. In this study, we identified that growth differentiation factor 15 (GDF15) is a glycolytic regulator, and GDF15 is highly expressed in MM cells and patient samples. Through gain-of-function and loss-of-function experiments, we demonstrated that GDF15 promotes MM cell proliferation and inhibits apoptosis. Moreover, GDF15 enhances Warburg-like metabolism in MM cells, as evidenced by increased glucose uptake, lactate production, and extracellular acidification rate, while reducing oxidative phosphorylation. Importantly, the tumor-promoting effects of GDF15 in MM cells are fermentation-dependent. Mechanistically, GDF15 was found to promote the expression of key glycolytic genes, particularly the glucose transporter GLUT1, through the activation of the TGFβ signaling pathway. Pharmacological inhibition of the TGFβ signaling pathway effectively abrogated the oncogenic activities of GDF15 in MM cells, including cell proliferation, apoptosis, and fermentation. In vivo experiments using a subcutaneous xenotransplanted tumor model confirmed that GDF15 knockdown led to a significant reduction in tumor growth, while GDF15 overexpression promoted tumor growth. Overall, our study provides insights into the molecular mechanisms underlying MM pathogenesis and highlights the potential of targeting GDF15-TGFβ signaling -glycolysis axis as a therapeutic approach for future therapeutic interventions in MM.

Non-canonical Wnt signaling pathway activated NFATC3 promotes GDF15 expression in MASH: prospective analyses of UK biobank proteomic data

BACKGROUND

Our previous research demonstrated that growth differentiation factor 15 (GDF15) exhibited superior predictive capability for metabolic dysfunction-associated steatohepatitis (MASH) development with an AUC of 0.86 at 10 years before disease diagnosis. However, the specific pathways and molecular mechanisms associated with GDF15 expression during MASH development remain to be fully investigated in humans.

METHODS

A nested case-control study comprising a MASH group of 78 individuals and three age- and sex-matched control groups (156 metabolic dysfunction-associated steatosis, 78 viral hepatitis, and 156 normal liver controls) was conducted. The baseline levels of GDF15-related transcription factors and upstream signaling pathways associated with the identified transcription factors were analysed prospectively.

RESULTS

The significantly higher level of nuclear factor of activated T cells 3 (NFATC3), a transcription factor for GDF15, was identified in the circulation in MASH patients compared to controls. Expression of the non-canonical Wnt signaling pathway that is upstream of NFATC3, and its related proteins CTHRC1, FRZB, SFRP1, and SFRP4, were highest in the MASH group, suggesting a non-canonical Wnt signaling/NFATC3/GDF-15 cascade in MASH disease pathogenesis. A predictive model for MASH development based on four biomarkers (CTHRC1, FRZB, NFATC3, and GDF15) showed an AUC of 0.90 at 10 years. A protein-clinical model that included these four circulating proteins and BMI yielded an AUC of 0.93 at 10 years.

CONCLUSIONS

Non-canonical Wnt signaling pathway may activate NFATC3 to promote GDF15 expression in MASH disease pathogenesis. These molecular mechanisms provide novel insights for developing targeted therapies that could modulate the non-canonical Wnt/NFATC3/GDF15 cascade to prevent/treat MASH.

Association between inflammatory biomarkers and the cognitive response to a multidomain intervention: secondary longitudinal analyses from the MAPT study

The aim of this study is to evaluate the association of systemic inflammation measured by plasma biomarkers with the change in cognitive function among participants from the Multidomain Alzheimer Preventive Trial (MAPT) exposed to the multidomain intervention (MI). Secondary analysis of the MAPT longitudinal data. MAPT is a randomized, placebo-controlled trial with 3 interventional groups (omega-3 only, MI only, omega-3 plus MI) and a control group. We tested the association of the change in cognitive function with inflammatory biomarkers (tumoral necrosis factor receptor-1 (TNFR1), monocyte chemoattractant protein-1 (MCP1), Growth Differentiation Factor-15 (GDF15), Interleukin-6 (IL6) and C reactive protein (CRP)) using mixed-effects models. A subgroup analysis was performed in those exposed to the MI. The response to the MI was defined as the change in the composite cognitive score over the 2-year clinical follow-up period. by modeling the response to the intervention and identifying "good responders", i.e., those in the 5th quintile of response at the end of the intervention period (2 years after the measurement of inflammatory markers). We included 1,527 participants (mean age 75.3, SD = 4.4; 64% female). Higher levels of GDF15 and TNFR1 were associated with a worse trajectory in the cognitive composite score in adjusted models. "Good responders" had an estimated mean change in the composite score of 0.051 (SD 0.062) over two years of intervention, compared to -0.136 (SD = 0.111) for the "not-good responders". Higher IL6 levels were associated with a decreased likelihood of being a "good responder" (OR = 0.22, p = 0.018, 95% CI 0.06; 0.78), with similar results for CRP (OR = 0.48, p = 0.009, 95% CI 0.28; 0.84). Higher inflammation was associated with a worse cognitive trajectory among nondemented participants and a lower likelihood of being classified as a "good responder" in those receiving a MI. Further confirmation of these findings could lead to the use of systemic inflammation as inclusion or stratification criteria in prevention trials.

Therapeutic Effects of GDF6-Overexpressing Mesenchymal Stem Cells through Upregulation of the GDF15/SIRT1 Axis in Age-Related Hearing Loss

BACKGROUND

It has been reported the therapeutic effects of mesenchymal stem cells (MSCs) on hearing loss. This study explored the therapeutic effects of growth differentiation factor 6 (GDF6) overexpression-induced MSCs (MSCs-GDF6) on age-related hearing loss (ARHL) and its underlying mechanisms.

METHODS

Reverse transcription-quantitative PCR and western blotting were used to evaluate gene expression. Flow cytometry and immunofluorescence assays were performed for the detection of apoptosis and autophagy, respectively. Hearing function and loss of outer hair cells (HCs) in ARHL rats were measured using the auditory brainstem response and cochlear silver nitrate staining, respectively. MSC proliferation was evaluated with the Cell Counting Kit-8 assay.

RESULTS

Growth differentiation factor 15 (GDF15) and sirtuin 1 (SIRT1) expression was significantly decreased in hydrogen peroxide (H2O2)-induced House Ear Institute-Organ of Corti 1 (HEI-OC1) cells and the cochlea of ARHL rats. Elevated apoptosis and blocked autophagic flux were uncovered in H2O2-induced HEI-OC1 cells and ARHL rats. GDF15 overexpression inhibited apoptosis and restored autophagic flux in vitro and in vivo. Meanwhile, GDF15 positively regulated SIRT1 protein expression. MSCs-GDF6 not only upregulated GDF15 and SIRT1 expression but also suppressed apoptosis and restored autophagic flux to reduce loss of HCs and hearing loss in ARHL rats.

CONCLUSIONS

MSCs-GDF6 prevented loss of HCs to relieve ARHL by inhibiting apoptosis and restoring autophagic flux, likely in association with upregulation of the GDF15/SIRT1 axis.