Growth differentiation factor 15 (GDF15): A survival protein with therapeutic potential in metabolic diseases

Verbascoside attenuates myocardial ischemia/reperfusion-induced ferroptosis following heterotopic heart transplantation via modulating GDF15/GPX4/SLC7A11 pathway

Myocardial cold ischemia/reperfusion (I/R) injury is an inevitable consequence of heart transplantation, significantly affecting survival rates and therapeutic outcomes. Growth Differentiation Factor 15 (GDF15) has been shown to regulate GPX4-mediated ferroptosis, playing a critical role in mitigating I/R injury. Meanwhile, verbascoside (VB), an active compound extracted from the herbaceous plant, has demonstrated myocardial protective effects. In this study, heart transplantation was performed using a modified non-suture cuff technique, with VB administered at a dose of 20 mg/kg/day via intraperitoneal injection for 3 days in vivo. In vitro, cardiomyocytes were pretreated with 50 µg/ml VB for 24 h. VB treatment significantly reduced histopathological injury, decreased myocardial injury markers, and inhibited ferroptosis and oxidative stress during myocardial cold I/R injury in vivo. In vitro experiments further demonstrated that GDF15 alleviates ferroptosis induced by hypoxic reoxygenation by upregulating GPX4. Therefore, it is concluded that VB preconditioning can effectively reduce ferroptosis induced by myocardial cold I/R after heterotopic heart transplantation, possibly through up-regulation of GDF15/GPX4/SLC7A11 pathway.

GDF15 Analogues Acting as GFRAL Ligands

Growth differentiation factor 15 (GDF15) is a TGF-β superfamily member involved in diverse physiological and pathological processes. It is expressed in various tissues and its circulating levels rise during exercise, aging, pregnancy, and conditions such as cancer, cardiovascular disease, and infections. The biological activities of GDF15, including anorexia and cachexia, are primarily mediated through the GFRAL receptor, localized in the brainstem and functioning via RET co-receptor recruitment. This signaling is crucial for energy homeostasis and nausea induction. Recent studies suggest a broader GFRAL distribution, potentially explaining GDF15's distinct roles. These findings sparked interest in leveraging GDF15-GFRAL pathways for therapeutic development. Two primary strategies include GDF15 analogues as GFRAL agonists for obesity treatment and GDF15-derived peptides as antagonists to counteract cancer-induced cachexia and related disorders. This review highlights advancements in understanding GDF15-GFRAL signaling and its implications, summarizing bioactive GDF15-derived molecules, their pharmacological applications, and offering insights into novel treatment avenues for GDF15-associated conditions.

NAG-1/GDF15 as a tumor suppressor in colorectal cancer: inhibition of β-catenin and NF-κB pathways via interaction with EpCAM

NAG-1/GDF15, a tumor suppressor, is synthesized as a pro-form in colorectal cancer (CRC) cells and undergoes cleavage to generate its mature form. While the biological function of pro-NAG-1/GDF15 remains unclear, our study reveals its crucial role in suppressing oncogenic signaling. We demonstrate that pro-NAG-1/GDF15 is predominantly retained within cells, whereas its mature form is secreted into the media. The expression of NAG-1/GDF15, or uncleavable R193A mutant, inhibits β-catenin and NF-κB signaling, key pathways in CRC progression. Mechanistically, the pro-NAG-1/GDF15 interacts with EpCAM, preventing its cleavage and nuclear translocation, thereby reducing β-catenin and NF-κB activity. This inhibition correlates with decreased expression of oncogenic targets such as cyclin D1 and c-myc. In vivo, NAG-1/GDF15 expression significantly reduces tumor growth in cancer xenograft models, accompanied by decreased proliferation and increased apoptosis. Furthermore, analysis of public datasets suggests that high NAG-1/GDF15 expression is associated with improved CRC patient survival. These findings highlight NAG-1/GDF15 via the formation of pro-NAG-1/GDF15 as a promising therapeutic target for cancer, with potential applications in modulating tumorigenic signaling pathways.

Biomarkers of cellular senescence predict risk of mild cognitive impairment: Results from the lifestyle interventions for elders (LIFE) study

OBJECTIVES

Cellular senescence, characterized by a marked and multifactorial senescence-associated secretory phenotype (SASP), is a potential unifying mechanism of aging and chronic disease. Most studies of the SASP have focused on frailty and other functional outcomes. Senescent cells have been detected in the brains of patients with Alzheimer's disease, but few studies have examined associations between plasma SASP markers and cognition. The objective of this study was to examine the cross-sectional and longitudinal associations between plasma SASP markers and mild cognitive impairment among older adults at high risk of mobility disability.

DESIGN

The Lifestyle Interventions for Elders (LIFE) study was a randomized controlled trial of a group-based physical activity program compared to a "successful aging" health education program to assess effects on major mobility disability that was conducted from February 2010 to December 2013.

SETTING

Recruitment occurred at eight centers in the United States.

PARTICIPANTS

We included 1,373 participants enrolled in the study with baseline measures of 27 biomarkers of cellular senescence and adjudication of mild cognitive impairment (MCI) and dementia at baseline and 24-month follow-up. At baseline, participants were aged 70-80, sedentary, and at high risk of mobility disability.

MEASUREMENTS

A neuropsychological assessment was administered at baseline and 24 months post-randomization. At both timepoints, a clinical adjudication committee determined whether individuals had a diagnosis of cognitively normal, MCI, or dementia; individuals with dementia at baseline were excluded. The concentrations of 26 of the 27 plasma proteins identified as components of the SASP were measured with commercially available Luminex xMAP multiplex magnetic bead-based immunoassays analyzed on the MAGPIX System while 1 protein (Activin A) was measured using an enzyme-linked immunosorbent assay.

RESULTS

Logistic regression models were used to examine the associations of each senescence biomarker, in quartiles, with baseline or incident MCI. Models stratified by clinical site and adjusted for intervention assignment, age, gender, race, and education. Among 1,373 participants, 117 (8.5%) were diagnosed with MCI at baseline. Increasing quartiles of myeloperoxidase (MPO) was associated with higher odds of MCI compared to quartile 1 (Q2: OR = 1.34, 95% CI: 0.74-2.45; Q3: OR = 1.43, 95% CI: 0.80-2.59; Q4: OR = 1.79, 95% CI: 1.02-3.22). Additionally, matrix metalloproteinase 1 (MMP1) quartiles 2-4 had lower odds of MCI compared to quartile 1 (Q2: OR = 0.61, 95% CI: 0.35-1.02; Q3: OR = 0.58, 95% CI: 0.33-0.98; Q4: OR = 0.64, 95% CI: 0.37-1.08). Of the 1,256 cognitively unimpaired participants at baseline, 141 (11.2%) were diagnosed with incident MCI or dementia at the 24-month follow-up. Compared to quartile 1, increasing baseline quartiles of MPO (Q2: OR = 1.10, 95% CI: 0.63-1.92; Q3: OR = 1.36, 95% CI: 0.80-2.33; Q4: OR = 1.92, 95% CI: 1.16-3.25) and matrix metalloproteinase 7 (MMP7, Q2: OR = 0.88, 95% CI: 0.47-1.62; Q3: OR = 1.46, 95% CI: 0.85-2.55; Q4: OR = 2.14, 95% CI: 1.28-3.65) were associated with increased odds of MCI or dementia at 24 months.

CONCLUSIONS

Among older adults at high risk of mobility disability, high plasma MPO was cross-sectionally and, along with MMP7, longitudinally associated with increased odds of MCI and dementia. In contrast, high MMP1 was cross-sectionally associated with reduced odds of MCI.

Growth differentiation factor 15: a valuable biomarker for the diagnosis and prognosis of late-onset form of multiple Acyl-CoA dehydrogenation deficiency

BACKGROUND

Multiple acyl-CoA Dehydrogenation Deficiency (MADD) is a hereditary metabolic disorder affecting the metabolism of fatty acids, amino acids, and choline, typically presenting with fat accumulation and mitochondrial abnormalities in muscle pathology. Growth differentiation factor 15 (GDF15) is a stress-responsive cytokine implicated in energy metabolism. Therefore, this study aimed to assess the level of GDF15 in patients with late-onset MADD and to evaluate its potential as a reliable biomarker for diagnosing symptoms and determining the severity of late-onset MADD.

METHODS

In this study, consecutive patients with MADD mitochondrial diseases were recruited from the Neuromuscular Center of Qilu Hospital, Shandong University, between April 2015 and October 2021. We measured serum GDF15 levels in patients with late-onset MADD and healthy controls. Additionally, we analyzed the messenger RNA(mRNA) expression of GDF15 and integrated stress response (ISR)-related factors, including CHOP, ATF5, and TRIB3, in the muscles.

RESULTS

Serum GDF15 levels in patients with late-onset MADD were 18.8 times higher than those in healthy controls. GDF15 levels decreased as the disease progressed, and its elecated levels correlated with anorexia symptoms. The mRNA expression of GDF15 and ISR-related factors in the muscles was higher in patients with late-onset MADD than in controls.

CONCLUSION

GDF15 levels were significantly elevated in symptomatic patients with late-onset MADD, likely due to mitochondrial dysfunction activating the ISR pathway. These findings suggest that GDF15 is a valuable biomarker for monitoring disease severity and symptomatology in patients with late-onset MADD.

Mapping growth differentiation factor-15 (GDF15)-mediated signaling pathways in cancer: insights into its role across different cancer types

Growth differentiation factor-15 (GDF15) is a cytokine/growth factor that belongs to the Transforming growth factor-ß (TGF-ß) protein family. The expression of GDF15 is low in most human organs under normal conditions. GDF15 is a stress-responsive cytokine primarily produced by macrophages in response to inflammatory stimuli. The altered expression of GDF15 is associated with many cancers due to the inflammation caused by the disease. GDF15 triggers the activity through its receptor Glial-derived neurotrophic factor-family receptor α-like (GFRAL) and mediates multiple downstream signaling cascades, which are involved in the progression of cancers. Considering the biological importance of GDF15 in different cancers, we applied data mining techniques to systematically compile and analyze the signaling events associated with GDF15 using NetPath criteria. This resulted in constructing a detailed GDF15-mediated signaling pathway map, enhancing our understanding of its molecular mechanisms in cancer. Furthermore, proteins linked to colorectal and breast cancer identified in our pathway map were cross-referenced with established cancer pathway databases to identify unannotated proteins, highlighting gaps in the current annotations. To investigate potential therapeutic strategies, we performed molecular docking simulations and identified Vitisifuran B as a novel inhibitor that could block the GDF15-GFRAL interaction. These findings suggest that Vitisifuran B could effectively modulate GDF15 signaling, offering a promising avenue for cancer therapeutics. This study underscores the power of computational approaches, such as data mining and molecular docking, in enhancing our understanding of GDF15 signaling in cancer and identifying potential inhibitors for therapeutic development.

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.

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.

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.

The importance of growth differentiation factor 15 and interleukin 6 serum levels in inflammatory bowel diseases

There are only scarce recent reports about the role of growth differentiation factor 15 (GDF-15) and some more data about interleukin-6 (IL-6) in inflammatory bowel diseases (IBD). We assessed GDF-15 and IL-6 serum levels in patients with IBD and associations with their characteristics. We included 122 and 71 stored samples from patients with Crohn's disease (CD) and ulcerative colitis (UC), respectively, and regular follow-up and 44 samples from healthy controls. Data regarding epidemiologic and disease characteristics were recorded. In CD, both GDF-15 and IL-6 levels were higher in active disease or all patients than controls (P ≤ 0.020) as well as patients with elevated CRP (P ≤ 0.008), endoscopically active disease (P ≤ 0.017), age ≥ 40 years (P ≤ 0.005) and active smokers (P ≤ 0.050) and were positively correlated with hospitalization numbers (P ≤ 0.019). GDF-15 levels were also positively correlated with flares within year-1 (P < 0.001). In UC, both GDF-15 and IL-6 levels were higher in clinically active or all patients than controls (P < 0.001), but they shared no other association with patient characteristics except for positive correlation with CRP. Only IL-6 levels were higher in active than inactive UC either clinically (P = 0.047) or endoscopically (P < 0.001) and were positively correlated with stool calprotectin (P = 0.021). GDF-15 was positively correlated to IL-6 levels only in UC (rs=0.591, P < 0.001) but not in CD. In conclusion, in CD, GDF-15 and IL-6 levels could constitute indexes of activity and even offer a prognostic index of disease progression. In UC, IL-6 could also represent an activity index, but the role of GDF-15 needs further evaluation.

Palmitate potentiates the SMAD3-PAI-1 pathway by reducing nuclear GDF15 levels

Nuclear growth differentiation factor 15 (GDF15) reduces the binding of the mothers' against decapentaplegic homolog (SMAD) complex to its DNA-binding elements. However, the stimuli that control this process are unknown. Here, we examined whether saturated fatty acids (FA), particularly palmitate, regulate nuclear GDF15 levels and the activation of the SMAD3 pathway in human skeletal myotubes and mouse skeletal muscle, where most insulin-stimulated glucose use occurs in the whole organism. Human LHCN-M2 myotubes and skeletal muscle from wild-type and Gdf15-/- mice fed a standard (STD) or a high-fat (HFD) diet were subjected to a series of studies to investigate the involvement of lipids in nuclear GDF15 levels and the activation of the SMAD3 pathway. The saturated FA palmitate, but not the monounsaturated FA oleate, increased the expression of GDF15 in human myotubes and, unexpectedly, decreased its nuclear levels. This reduction was prevented by the nuclear export inhibitor leptomycin B. The decrease in nuclear GDF15 levels caused by palmitate was accompanied by increases in SMAD3 protein levels and in the expression of its target gene SERPINE1, which encodes plasminogen activator inhibitor 1 (PAI-1). HFD-fed Gdf15-/- mice displayed aggravated glucose intolerance compared to HFD-fed WT mice, with increased levels of SMAD3 and PAI-1 in the skeletal muscle. The increased PAI-1 levels in the skeletal muscle of HFD-fed Gdf15-/- mice were accompanied by a reduction in one of its targets, hepatocyte growth factor (HGF)α, a cytokine involved in glucose metabolism. Interestingly, PAI-1 acts as a ligand of signal transducer and activator of transcription 3 (STAT3) and the phosphorylation of this transcription factor was exacerbated in HFD-fed Gdf15-/- mice compared to HFD-fed WT mice. At the same time, the protein levels of insulin receptor substrate 1 (IRS-1) were reduced. These findings uncover a potential novel mechanism through which palmitate induces the SMAD3-PAI-1 pathway to promote insulin resistance in skeletal muscle by reducing nuclear GDF15 levels.

The clinical utility in hospital-wide use of growth differentiation factor 15 as a biomarker for mitochondrial DNA-related disorders

Clinical recognition of primary mitochondrial disorders (PMD) is difficult due to the clinical and genetic heterogeneity. Whereas lactate has low sensitivity and specificity, in structured clinical studies growth differentiation factor 15 (GDF15) has shown promise with elevations in mitochondrial DNA (mtDNA)-related PMD, but its specificity has been questioned. In a tertiary care hospital-wide study, medical records were retrospectively reviewed from 418 cases where GDF15 levels were obtained by clinicians. Patients were classified into patients with PMD due to mtDNA-related defects (mtDNA maintenance, mtDNA deletions, and mtDNA-encoded tRNA variants), PMD due to structural defects or other nuclear causes, and in non-mitochondrial disease. Patients with liver disease or systemic critical illness were excluded. GDF15 was assayed in a clinical laboratory with a cutoff of 750 ng/L. There were 38 mtDNA-related PMD (GDF15 >750 pg/mL in 76%), 35 other nuclear DNA-encoded PMD or structural subunits (31% elevated GDF15), 309 non-mitochondrial disorders (13% elevated GDF15). Based on the highest Youden J-index, the optimal cut-off value to identify these target mtDNA-related disorders was 815 pg/mL, with sensitivity 76%, specificity 88%, positive predictive value of 41% and negative predictive value of 97%. At this optimized cutoff level, mtDNA-encoded PMD patients had elevated GDF15 in 76%, nuclear DNA-encoded PMD in 26%, and non-mitochondrial disorders in 11% of patients. Thus, in a real-life clinical setting, after excluding abnormal liver function and critical illness, GDF15 had good clinical utility increasing the odds at predicting mtDNA-related primary mitochondrial disorders 14-fold, but not for structural or other nuclear-encoded primary mitochondrial disorders.

Plasma proteomics identify biomarkers and undulating changes of brain aging

Proteomics enables the characterization of brain aging biomarkers and discernment of changes during brain aging. We leveraged multimodal brain imaging data from 10,949 healthy adults to estimate brain age gap (BAG), an indicator of brain aging. Proteome-wide association analysis across 4,696 participants of 2,922 proteins identified 13 significantly associated with BAG, implicating stress, regeneration and inflammation. Brevican (BCAN) (β = -0.838, P = 2.63 × 10-10) and growth differentiation factor 15 (β = 0.825, P = 3.48 × 10-11) showed the most significant, and multiple, associations with dementia, stroke and movement functions. Dysregulation of BCAN affected multiple cortical and subcortical structures. Mendelian randomization supported the causal association between BCAN and BAG. We revealed undulating changes in the plasma proteome across brain aging, and profiled brain age-related change peaks at 57, 70 and 78 years, implicating distinct biological pathways during brain aging. Our findings revealed the plasma proteomic landscape of brain aging and pinpointed biomarkers for brain disorders.

Metformin inhibits migration and epithelial-to-mesenchymal transition in non-small cell lung cancer cells through AMPK-mediated GDF15 induction

The growth differentiation factor 15 (GDF15) may serve as a biomarker of metformin, which mediates the bodyweight lowering effect of metformin. However, whether GDF15 also serves as a molecular target of metformin to inhibit carcinogenesis remains largely unknown. This study examined the role and molecular mechanisms of GDF15 in the anticancer effects of metformin in non-small cell lung cancer (NSCLC) cells, which has never been reported before. We found that metformin significantly inhibited the migration of NSCLC A549 and NCI-H460 cells and reduced the expression of epithelial-to-mesenchymal transition (EMT)-related molecules, including neuro-cadherin (N-cadherin), matrix metalloproteinase 2 (MMP2), and the zinc finger transcription factor Snail, but increased epithelial cadherin (E-cadherin) expression. Furthermore, metformin increased GDF15 and its upstream transcription factors activated transcription factor 4 (ATF4) and C/EBP-homologous protein (CHOP) expressions and increased AMP-activated protein kinase (AMPK) phosphorylation in NSCLC cells. GDF15 siRNA partially reverses the inhibitory effect of metformin on NSCLC cell migration. Moreover, metformin-induced increases in GDF15, CHOP, and ATF4 expression and the inhibition of migration were partially reversed by treatment with Compound C, a specific AMPK inhibitor. Meanwhile, metformin significantly inhibited NCI-H460 xenograft tumor growth in nude mice, increased GDF15 expression, and regulated EMT- and migration-related protein expression in xenograft tumors. In conclusion, our results provide novel insights into revealing that GDF15 can serve as a potential molecular target of metformin owing to its anti-cancer effect in NSCLC, which is mediated by AMPK activation.

Proteomic Analysis of Microsomal Proteins Reveals That MVP Is Crucial for the Secretion of GDF-15, Which in Turn Promotes the Neuroendocrine Differentiation of PCa Cells

Neuroendocrine prostate cancer (NEPC) is an aggressive androgen-independent PCa (AIPC) that tends to resist treatment. Understanding its progression and resistance could improve survival outcomes. Previous studies on PCa cells highlighted microsomal proteins' role in PCa progression, but their role in the progression of NEPC remains unclear. Thus, we investigated microsomal proteins in in vitro differentiated NE-LNCaP cells and their role in NED of PCa. Microsomal proteomics revealed two cancer-associated proteins GDF-15 and MVP as elevated in NE-LNCaP cells with GDF-15 among the top 5 upregulated proteins. MVP is elevated in NE-LNCaP and is also increased in NCI-H660 microsomes compared to LNCaP. GO and protein network analysis showed that different molecular networks are affected by microsomal protein enrichment, and MVP and GDF-15 are mapped to functional subnetworks associated with cancer. Remarkably, GDF-15 and MVP are essential for LNCaP cell differentiation when stimulated with Forskolin. Interestingly, AKT and MAPK/ERK signaling pathways are significantly upregulated in NE-LNCaP and NCI-H660 cells with the direct involvement of GDF-15. In summary, we have uncovered that GDF-15 and MVP are involved in NED, with MVP being essential for GDF-15 secretion, promoting NED in PCa cells. These findings provide insights into NED mechanisms and suggest potential therapeutic targets or biomarkers for NEPC.

Diagnostic value of serum GDF-15 in patients with pseudomyxoma peritonei

BACKGROUND AND AIMS

Pseudomyxoma peritonei (PMP) is a rare malignancy that lacks a highly sensitive and specific biomarker for its diagnosis. Identifying reliable serum markers is crucial for improving the diagnostic accuracy and management of PMP. This study aims to explore the diagnostic value of serum growth differentiation factor 15 (GDF-15) in patients with PMP.

MATERIAL AND METHODS

We carried on a 1:1 matched case-control study. 44 patients with PMP hospitalized in Aerospace Center Hospital were recruited as cases, and 44 sex- and age-matched apparently healthy participants were selected as controls. The serum GDF-15 concentrations were tested using an ELISA method. The diagnostic value of GDF-15 in PMP patients was assessed by receiver operating characteristic (ROC) curve analysis.

RESULTS

The median serum GDF-15 level in PMP patients was 1192.77 (843.03-1879.06) pg/mL, notably higher than that in healthy controls [533.27 (410.46-641.47) pg/mL] (P<0.001). The area under the curve (AUC) of serum GDF-15 for PMP diagnosis was 0.907, the optimal diagnostic threshold value was 644.58 pg/mL, the sensitivity was 93.18 %, and the specificity was 77.27 %. The AUC of GDF-15 combined with carbohydrate antigen 125 (CA125) was larger than that of GDF-15 alone (P=0.027), and the sensitivity and specificity achieved 86.36 % and 95.45 %. GDF-15 levels showed a significant correlation with age (P=0.042), with younger PMP patients exhibiting notably lower concentrations of GDF-15 compared to older patients.

CONCLUSION

Serum GDF-15 could become a new marker for the PMP diagnosis. The combination of GDF-15 and CA125 demonstrated superior diagnostic performance for PMP compared to GDF-15 alone, achieving a sensitivity of 86.36% and a specificity of 95.45%.

Targeting the GDF15 Signalling for Obesity Treatment: Recent Advances and Emerging Challenges

The growth differentiation factor 15 (GDF15)-glial cell-derived neurotrophic factor family receptor alpha-like (GFRAL) pathway plays a crucial role in the regulation of metabolism, appetite and body weight control. Obesity is an increasingly prevalent chronic disease worldwide, necessitating effective treatment strategies. Recent preclinical and clinical studies have highlighted that targeting the GDF15-GFRAL signalling pathway is a promising approach for treating obesity, particularly because it has minimal impact on skeletal muscle mass, which is essential to preserve during weight loss. Given its distinctive mechanisms, the GDF15-GFRAL axis represents an attractive target for addressing various metabolic disorders, especially obesity. In this review, we will explore how the GDF15-GFRAL axis is regulated, its distribution in the body and its role in the regulation of metabolism, appetite and obesity. Additionally, we will discuss recent advances and potential challenges in targeting the GDF15-GFRAL axis for obesity treatment.

Hepatocyte-specific GDF15 overexpression improves high-fat diet-induced obesity and hepatic steatosis in mice via hepatic FGF21 induction

GDF15 and FGF21, stress-responsive cytokines primarily secreted from the liver, are promising therapeutic targets for metabolic dysfunction-associated steatotic liver disease (MASLD). However, the interaction between GDF15 and FGF21 remains unclear. We examined the effects of hepatocyte-specific GDF15 or FGF21 overexpression in high-fat diet (HFD)-fed mice for 8 weeks. Hydrodynamic injection of GDF15 or FGF21 sustained high circulating levels of GDF15 or FGF21, respectively, resulting in marked reductions in body weight, epididymal fat mass, insulin resistance, and hepatic steatosis. In addition, GDF15 treatment led to early reduction in body weight despite no change in food intake, indicating the role of GDF15 other than appetite loss. GDF15 treatment increased liver-derived serum FGF21 levels, whereas FGF21 treatment did not affect GDF15 expression. GDF15 promoted eIF2α phosphorylation and XBP1 splicing, leading to FGF21 induction. In murine AML12 hepatocytes treated with free fatty acids (FFAs), GDF15 overexpression upregulated Fgf21 mRNA levels and promoted eIF2α phosphorylation and XBP1 splicing. Overall, continuous exposure to excess FFAs resulted in a gradual increase of β-oxidation-derived reactive oxygen species and endoplasmic reticulum stress, suggesting that GDF15 enhanced this pathway and induced FGF21 expression. GDF15- and FGF21-related crosstalk is an important pathway for the treatment of MASLD.

Growth differentiation factor 15: Emerging role in liver diseases

Growth differentiation factor 15 (GDF15) is a cell stress-response cytokine within the transforming growth factor-β (TGFβ) superfamily. It is known to exert diverse effects on many metabolic pathways through its receptor GFRAL, which is expressed in the hindbrain, and transduces signals through the downstream receptor tyrosine kinase Ret. Since the liver is the core organ of metabolism, summarizing the functions of GDF15 is highly important. In this review, we assessed the relevant literature regarding the main metabolic, inflammatory, fibrogenic, tumorigenic and other effects of GDF15 on different liver diseases, including Metabolic dysfunction-associated steatotic liver disease(MASLD), alcohol and drug-induced liver injury, as well as autoimmune and viral hepatitis, with a particular focus on the pathogenesis of MASLD progression from hepatic steatosis to MASH, liver fibrosis and even hepatocellular carcinoma (HCC). Finally, we discuss the prospects of the clinical application potential of GDF15 along with its research and development progress. With better knowledge of GDF15, increasing in-depth research will lead to a new era in the field of liver diseases.

ATF4-dependent and independent mitokine secretion from OPA1 deficient skeletal muscle in mice is sexually dimorphic

Introduction

Reducing Optic Atrophy 1 (OPA1) expression in skeletal muscle in male mice induces Activation Transcription Factor 4 (ATF4) and the integrated stress response (ISR). Additionally, skeletal muscle secretion of Fibroblast Growth Factor 21 (FGF21) is increased, which mediates metabolic adaptations including resistance to diet-induced obesity (DIO) and glucose intolerance in these mice. Although FGF21 induction in this model can be reversed with pharmacological attenuation of ER stress, it remains to be determined if ATF4 is responsible for FGF21 induction and its metabolic benefits in this model.

Methods

We generated mice with homozygous floxed Opa1 and Atf4 alleles and a tamoxifen-inducible Cre transgene controlled by the human skeletal actin promoter to enable simultaneous depletion of OPA1 and ATF4 in skeletal muscle (mAO DKO). Mice were fed high fat (HFD) or control diet and evaluated for ISR activation, body mass, fat mass, glucose tolerance, insulin tolerance and circulating concentrations of FGF21 and growth differentiation factor 15 (GDF15).

Results

In mAO DKO mice, ATF4 induction is absent. Other indices of ISR activation, including XBP1s, ATF6, and CHOP were induced in mAO DKO males, but not in mOPA1 or mAO DKO females. Resistance to diet-induced obesity was not reversed in mAO DKO mice of both sexes. Circulating FGF21 and GDF15 illustrated sexually dimorphic patterns. Loss of OPA1 in skeletal muscle increases circulating FGF21 in mOPA1 males, but not in mOPA1 females. Additional loss of ATF4 decreased circulating FGF21 in mAO DKO male mice, but increased circulating FGF21 in female mAO DKO mice. Conversely, circulating GDF15 was increased in mAO DKO males and mOPA1 females, but not in mAO DKO females.

Conclusion

Sex differences exist in the transcriptional outputs of the ISR following OPA deletion in skeletal muscle. Deletion of ATF4 in male and female OPA1 KO mice does not reverse the resistance to DIO. Induction of circulating FGF21 is ATF4 dependent in males, whereas induction of circulating GDF15 is ATF4 dependent in females. Elevated GDF15 in males and FGF21 in females could reflect activation by other transcriptional outputs of the ISR, that maintain mitokine-dependent metabolic protection in an ATF4-independent manner.

Discovery of NFκB2-Coordinated Dual Regulation of Mitochondrial and Nuclear Genomes Leads to an Effective Therapy for Acute Myeloid Leukemia

Acute myeloid leukemia (AML) has a poor survival rate for both pediatric and adult patients due to its frequent relapse. To elucidate the bioenergetic principle underlying AML relapse, we investigated the transcriptional regulation of mitochondrial-nuclear dual genomes responsible for metabolic plasticity in treatment-resistant blasts. Both the gain and loss of function results demonstrated that NFκB2, a noncanonical transcription factor (TF) of the NFκB (nuclear factor kappa-light-chain-enhancer of activated B cells) family, can control the expression of TFAM (mitochondrial transcription factor A), which is known to be essential for metabolic biogenesis. Furthermore, genetic tracking and promoter assays revealed that NFκB2 is in the mitochondria and can bind the specific "TTGGGGGGTG" region of the regulatory D-loop domain to activate the light-strand promoter (LSP) and heavy-strand promoter 1 (HSP1), promoters of the mitochondrial genome. Based on our discovery of NFκB2's novel function of regulating mitochondrial-nuclear dual genomes, we explored a novel triplet therapy including inhibitors of NFκB2, tyrosine kinase, and mitochondrial ATP synthase that effectively eliminated primary AML blasts with mutations of the FMS-related receptor tyrosine kinase 3 (FLT3) and displayed minimum toxicity to control cells ex vivo. As such, effective treatments for AML must include strong inhibitory actions on the dual genomes mediating metabolic plasticity to improve leukemia prognosis.

Metabolic Crosstalk between Liver and Brain: From Diseases to Mechanisms

Multiple organs and tissues coordinate to respond to dietary and environmental challenges. It is interorgan crosstalk that contributes to systemic metabolic homeostasis. The liver and brain, as key metabolic organs, have their unique dialogue to transmit metabolic messages. The interconnected pathogenesis of liver and brain is implicated in numerous metabolic and neurodegenerative disorders. Recent insights have positioned the liver not only as a central metabolic hub but also as an endocrine organ, capable of secreting hepatokines that transmit metabolic signals throughout the body via the bloodstream. Metabolites from the liver or gut microbiota also facilitate a complex dialogue between liver and brain. In parallel to humoral factors, the neural pathways, particularly the hypothalamic nuclei and autonomic nervous system, are pivotal in modulating the bilateral metabolic interplay between the cerebral and hepatic compartments. The term "liver-brain axis" vividly portrays this interaction. At the end of this review, we summarize cutting-edge technical advancements that have enabled the observation and manipulation of these signals, including genetic engineering, molecular tracing, and delivery technologies. These innovations are paving the way for a deeper understanding of the liver-brain axis and its role in metabolic homeostasis.

Overview of growth differentiation factor 15 (GDF15) in metabolic diseases

GDF15 is a stress response cytokine and a distant member of the transforming growth factor beta (TGFβ) superfamily, its levels increase in response to cell stress and certain diseases in the serum. To exert its effects, GDF15 binds to glial-derived neurotrophic factor (GDNF) receptor alpha-like (GFRAL), which was firstly identified in 2017 and highly expressed in the brain stem. Many studies have demonstrated that elevated serum GDF15 is associated with anorexia and weight loss. Herein, we focus on the biology of GDF15, specifically how this circulating protein regulates appetite and metabolism in influencing energy homeostasis through its actions on hindbrain neurons to shed light on its impact on diseases such as obesity and anorexia/cachexia syndromes. It works as an endocrine factor and transmits metabolic signals leading to weight reduction effects by directly reducing appetite and indirectly affecting food intake through complex mechanisms, which could be a promising target for the treatment of energy-intake disorders.

Growth Differentiation Factor-15 and Clinical Outcomes in Lower Extremity Artery Disease

AIM

Lower extremity artery disease (LEAD) is an increasingly common health problem that is associated with high mortality due to thrombotic and bleeding events. Growth differentiation factor-15 (GDF15), a stress-response cytokine belonging to the transforming growth factor-beta superfamily, is associated with cardiovascular disease and its outcomes. The aim of the present study was to examine the effect of serum GDF15 levels on clinical outcomes in patients with LEAD.

METHODS

We measured serum GDF15 levels in 200 patients with LEAD before their initial endovascular therapy. The primary endpoint was the all-cause mortality rate. The secondary endpoints, on the other hand, were thrombotic and bleeding events, such as cerebral infarction, acute coronary syndrome, acute limb ischemia, and Bleeding Academic Research Consortium types 3 and 5.

RESULTS

The serum GDF15 levels increased with advancing Fontaine class. Kaplan-Meier analysis revealed that the high-GDF15 group (≥ 2,275 pg/mL) had higher rates of all-cause deaths and thrombotic and bleeding events than the low-GDF15 group (＜2,275 pg/mL). Multivariate Cox proportional-hazards regression analysis revealed that GDF15 was an independent predictor of all-cause mortality and thrombotic and bleeding events after adjusting for confounding risk factors. When the ABC-AF-bleeding score was substituted for GDF15, similar results were obtained.

CONCLUSION

Serum GDF15 levels were associated with all-cause mortality and thrombotic and bleeding events in patients with LEAD. Serum GDF15 is a potentially useful marker of clinical outcomes, specifically for tracking thrombotic and bleeding events in patients with LEAD.

Different roles of circulating and intramuscular GDF15 as markers of skeletal muscle health

Introduction

Growth Differentiation Factor 15 (GDF15) is a mitokine expressed in response to various stresses whose circulating levels increase with age and are associated with numerous pathological conditions, including muscle wasting and sarcopenia. However, the use of circulating GDF15 (c-GDF15) as a biomarker of sarcopenia is still debated. Moreover, the role of GDF15 intracellular precursor, pro-GDF15, in human skeletal muscle (SM-GDF15) is not totally understood. In order to clarify these points, the association of both forms of GDF15 with parameters of muscle strength, body composition, metabolism and inflammation was investigated.

Methods

the levels of c-GDF15 and SM-GDF15 were evaluated in plasma and muscle biopsies, respectively, of healthy subjects (HS) and patients with lower limb mobility impairment (LLMI), either young (<40 years-old) or old (>70 years-old). Other parameters included in the analysis were Isometric Quadriceps Strength (IQS), BMI, lean and fat mass percentage, Vastus lateralis thickness, as well as circulating levels of Adiponectin, Leptin, Resistin, IGF-1, Insulin, IL6, IL15 and c-PLIN2. Principal Component Analysis (PCA), Canonical Discriminant Analysis (CDA) and Receiving Operating Characteristics (ROC) analysis were performed.

Results

c-GDF15 but not SM-GDF15 levels resulted associated with decreased IQS and IGF-1 levels in both HS and LLMI, while only in LLMI associated with increased levels of Resistin. Moreover, in LLMI both c-GDF15 and SM-GDF15 levels were associated with IL-6 levels, but interestingly SM-GDF15 is lower in LLMI with respect to HS. Furthermore, a discrimination of the four groups of subjects based on these parameters was possible with PCA and CDA. In particular HS, LLMI over 70 years or under 40 years of age were discriminated based on SM-GDF15, c-GDF15 and Insulin levels, respectively.

Conclusion

our data support the idea that c-GDF15 level could be used as a biomarker of decreased muscle mass and strength. Moreover, it is suggested that c-GDF15 has a different diagnostic significance with respect to SM-GDF15, which is likely linked to a healthy and active state.

GDF15 ameliorates sepsis-induced lung injury via AMPK-mediated inhibition of glycolysis in alveolar macrophage

Growth differentiation factor 15 (GDF15) as a stress response cytokine is involved in the development and progression of several diseases associated with metabolic disorders. However, the regulatory role and the underlying mechanisms of GDF15 in sepsis remain poorly defined. Our study analyzed the levels of GDF15 and its correlations with the clinical prognosis of patients with sepsis. In vivo and in vitro models of sepsis were applied to elucidate the role and mechanisms of GDF15 in sepsis-associated lung injury. We observed strong correlations of plasma GDF15 levels with the levels of C-reactive protein (CRP), procalcitonin (PCT), lactate dehydrogenase (LDH), and lactate as well as Sequential Organ Failure Assessment (SOFA) scores in patients with sepsis. In the mouse model of lipopolysaccharide-induced sepsis, recombinant GDF15 inhibited the proinflammatory responses and alleviated lung tissue injury. In addition, GDF15 decreased the levels of cytokines produced by alveolar macrophages (AMs). The anti-inflammatory effect of glycolysis inhibitor 2-DG on AMs during sepsis was mediated by GDF15 via inducing the phosphorylation of the α-subunit of eukaryotic initiation factor 2 (eIF2α) and the expression of activating transcription factor 4 (ATF4). Furthermore, we explored the mechanism underlying the beneficial effects of GDF15 and found that GDF15 inhibited glycolysis and mitogen-activated protein kinases (MAPK)/nuclear factor-κB (NF-κB) signaling via promoting AMPK phosphorylation. This study demonstrated that GDF15 inhibited glycolysis and NF-κB/MAPKs signaling via activating AMP-activated protein kinase (AMPK), thereby alleviating the inflammatory responses of AMs and sepsis-associated lung injury. Our findings provided new insights into novel therapeutic strategies for treating sepsis.

Gastric GDF15 levels are regulated by age, sex, and nutritional status in rodents and humans

AIM

Growth differentiation factor 15 (GDF15) is a stress response cytokine that has been proposed as a relevant metabolic hormone. Descriptive studies have shown that plasma GDF15 levels are regulated by short term changes in nutritional status, such as fasting, or in obesity. However, few data exist regarding how GDF15 levels are regulated in peripheral tissues. The aim of the present work was to study the variations on gastric levels of GDF15 and its precursor under different physiological conditions, such as short-term changes in nutritional status or overfeeding achieved by HFD. Moreover, we also address the sex- and age-dependent alterations in GDF15 physiology.

METHODS

The levels of gastric and plasma GDF15 and its precursor were measured in lean and obese mice, rats and humans by western blot, RT-PCR, ELISA, immunohistochemistry and by an in vitro organ culture system.

RESULTS

Our results show a robust regulation of gastric GDF15 production by fasting in rodents. In obesity an increase in GDF15 secretion from the stomach is reflected with an increase in circulating levels of GDF15 in rats and humans. Moreover, gastric GDF15 levels increase with age in both rats and humans. Finally, gastric GDF15 levels display sexual dimorphism, which could explain the difference in circulating GFD15 levels between males and females, observed in both humans and rodents.

CONCLUSIONS

Our results provide clear evidence that gastric GDF15 is a critical contributor of circulating GDF15 levels and can explain some of the metabolic effects induced by GDF15.

Influence of Growth Differentiation Factor 15 on Intraocular Pressure in Mice

Growth differentiation factor 15 (GDF15), a stress-sensitive cytokine, and a distant member of the transforming growth factor β superfamily, has been shown to exhibit increased levels with aging, and in various age-related pathologies. Although GDF15 levels are elevated in the aqueous humor (AH) of glaucoma (optic nerve atrophy) patients, the possible role of this cytokine in the modulation of intraocular pressure (IOP) or AH outflow is unknown. The current study addresses this question using transgenic mice expressing human GDF15 and GDF15 null mice, and by perfusing enucleated mouse eyes with recombinant human GDF15 (rhGDF15). Treatment of primary cultures of human trabecular meshwork cells with a telomerase inhibitor, an endoplasmic reticulum stress-inducing agent, hydrogen peroxide, or an autophagy inhibitor resulted in significant elevation in GDF15 levels relative to the respective control cells. rhGDF15 stimulated modest but significant increases in the expression of genes encoding the extracellular matrix, cell adhesion proteins, and chemokine receptors (C-C chemokine receptor type 2) in human trabecular meshwork cells compared with controls, as deduced from the differential transcriptional profiles using RNA-sequencing analysis. There was a significant increase in IOP in transgenic mice expressing human GDF15, but not in GDF15 null mice, compared with the respective wild-type control mice. The AH outflow facility was decreased in enucleated wild-type mouse eyes perfused with rhGDF15. Light microcopy-based histologic examination of the conventional AH outflow pathway tissues did not reveal identifiable differences between the GDF15-targeted and control mice. Taken together, these results reveal the modest elevation of IOP in mice expressing human GDF15 possibly stemming from decreased AH outflow through the trabecular pathway.

Regenerative inflammation: When immune cells help to re-build tissues

Inflammation is an essential immune response critical for responding to infection, injury and maintenance of tissue homeostasis. Upon injury, regenerative inflammation promotes tissue repair by a timed and coordinated infiltration of diverse cell types and the secretion of growth factors, cytokines and lipids mediators. Remarkably, throughout evolution as well as mammalian development, this type of physiological inflammation is highly associated with immunosuppression. For instance, regenerative inflammation is the consequence of an in situ macrophage polarization resulting in a transition from pro-inflammatory to anti-inflammatory/pro-regenerative response. Immune cells are the first responders upon injury, infiltrating the damaged tissue and initiating a pro-inflammatory response depleting cell debris and necrotic cells. After phagocytosis, macrophages undergo multiple coordinated metabolic and transcriptional changes allowing the transition and dictating the initiation of the regenerative phase. Differences between a highly efficient, complete ad integrum tissue repair, such as, acute skeletal muscle injury, and insufficient regenerative inflammation, as the one developing in Duchenne Muscular Dystrophy (DMD), highlight the importance of a coordinated response orchestrated by immune cells. During regenerative inflammation, these cells interact with others and alter the niche, affecting the character of inflammation itself and, therefore, the progression of tissue repair. Comparing acute muscle injury and chronic inflammation in DMD, we review how the same cells and molecules in different numbers, concentration and timing contribute to very different outcomes. Thus, it is important to understand and identify the distinct functions and secreted molecules of macrophages, and potentially other immune cells, during tissue repair, and the contributors to the macrophage switch leveraging this knowledge in treating diseases.

Intellectual disability and autism in propionic acidemia: a biomarker-behavioral investigation implicating dysregulated mitochondrial biology

Propionic acidemia (PA) is an autosomal recessive condition (OMIM #606054), wherein pathogenic variants in PCCA and PCCB impair the activity of propionyl-CoA carboxylase. PA is associated with neurodevelopmental disorders, including intellectual disability (ID) and autism spectrum disorder (ASD); however, the correlates and mechanisms of these outcomes remain unknown. Using data from a subset of participants with PA enrolled in a dedicated natural history study (n = 33), we explored associations between neurodevelopmental phenotypes and laboratory parameters. Twenty (61%) participants received an ID diagnosis, and 12 of the 31 (39%) who were fully evaluated received the diagnosis of ASD. A diagnosis of ID, lower full-scale IQ (sample mean = 65 ± 26), and lower adaptive behavior composite scores (sample mean = 67 ± 23) were associated with several biomarkers. Higher concentrations of plasma propionylcarnitine, plasma total 2-methylcitrate, serum erythropoietin, and mitochondrial biomarkers plasma FGF21 and GDF15 were associated with a more severe ID profile. Reduced 1-13C-propionate oxidative capacity and decreased levels of plasma and urinary glutamine were also associated with a more severe ID profile. Only two parameters, increased serum erythropoietin and decreased plasma glutamine, were associated with ASD. Plasma glycine, one of the defining features of PA, was not meaningfully associated with either ID or ASD. Thus, while both ID and ASD were commonly observed in our PA cohort, only ID was robustly associated with metabolic parameters. Our results suggest that disease severity and associated mitochondrial dysfunction may play a role in CNS complications of PA and identify potential biomarkers and candidate surrogate endpoints.

Interplay between Senescence and Macrophages in Diabetic Cardiomyopathy: A Review of the Potential Role of GDF-15 and Klotho

Type 2 diabetes mellitus (T2DM) is a critical health problem, with 700 million diagnoses expected worldwide by 2045. Uncontrolled high blood glucose levels can lead to serious complications, including diabetic cardiomyopathy (DCM). Diabetes induces cardiovascular aging and inflammation, increasing cardiomyopathy risk. DCM is characterized by structural and functional abnormalities in the heart. Growing evidence suggests that cellular senescence and macrophage-mediated inflammation participate in the pathogenesis and progression of DCM. Evidence indicates that growth differentiation factor-15 (GDF-15), a protein that belongs to the transforming growth factor-beta (TGF-β) superfamily, is associated with age-related diseases and exerts an anti-inflammatory role in various disease models. Although further evidence suggests that GDF-15 can preserve Klotho, a transmembrane antiaging protein, emerging research has elucidated the potential involvement of GDF-15 and Klotho in the interplay between macrophages-induced inflammation and cellular senescence in the context of DCM. This review explores the intricate relationship between senescence and macrophages in DCM while highlighting the possible contributions of GDF-15 and Klotho.

Skin advanced glycation end-products as indicators of the metabolic profile in diabetes mellitus: correlations with glycemic control, liver phenotypes and metabolic biomarkers

INTRODUCTION

The production of advanced glycation end-products (AGEs) is a key pathomechanism related to the complications of diabetes mellitus. The measurement of HbA1c as one of the AGEs is widely used in the clinic, but also other proteins undergo glycation in the course of diabetes. Here, we measure skin AGEs (SAGEs) in patients with diabetes type 1 (DM1) and type 2 (DM2) and correlate them with metabolic markers as well as non-invasively measured liver fibrosis and steatosis.

PATIENTS AND METHODS

In this cross-sectional study, a total of 64 patients with either DM1 or DM2 and 28 healthy controls were recruited. SAGEs were measured using autofluorescence (AGE Reader). Liver fibrosis and steatosis were quantified using transient elastography, which determines liver stiffness measurement (LSM) and controlled attenuation parameter (CAP). FGF19, FGF21 and GDF-15 were measured in blood samples using ELISA.

RESULTS

SAGEs were elevated in both groups of patients with diabetes as compared to healthy controls (both p < 0.001) and were higher in patients with DM2 in comparison to DM1 (p = 0.006). SAGEs correlated positively with HbA1c (r = 0.404, p < 0.001), CAP (r = 0.260, p = 0.016) and LSM (r = 0.356, p < 0.001), and negatively with insulin growth factor binding protein 3 (p < 0.001). We also detected a positive correlation between GDF15 and SAGEs (r = 0.469, p < 0.001).

CONCLUSIONS

SAGEs are significantly elevated in patients with both DM types 1 and 2 and correlate with metabolic markers, including HbA1c and GDF15. They might also help to detect patients with advanced liver injury in the setting of diabetes.

Biomarkers of Cellular Senescence Predict the Onset of Mobility Disability and Are Reduced by Physical Activity in Older Adults

Studies in mice and cross-sectional studies in humans support the premise that cellular senescence is a contributing mechanism to age-associated deficits in physical function. We tested the hypotheses that circulating proteins secreted by senescent cells are (i) associated with the incidence of major mobility disability (MMD), the development of persistent mobility disability (PMMD), and decrements in physical functioning in older adults, and (ii) influenced by physical activity (PA). Using samples and data obtained longitudinally from the Lifestyle Interventions in Elders Study clinical trial, we measured a panel of 27 proteins secreted by senescent cells. Among 1 377 women and men randomized to either a structured PA intervention or a healthy aging (HA) intervention, we observed significant associations between several senescence biomarkers, most distinctly vascular endothelial growth factor A (VEGFA), tumor necrosis factor receptor 1 (TNFR1), and matrix metallopeptidase 7 (MMP7), and the onset of both MMD and PMMD. Moreover, VEGFA, GDF15, osteopontin, and other senescence biomarkers were associated with reductions in short physical performance battery scores. The change in senescence biomarkers did not differ between PA and HA participants. In the whole cohort, higher levels of PA were associated with significantly greater reductions in 10 senescence-related proteins at 12 and/or 24 months. These data reinforce cellular senescence as a contributing mechanism of age-associated functional decline and the potential for PA to attenuate this hallmark of aging. Clinical Trials Registration Number: NCT01072500.

GDF15 as a key disease target and biomarker: linking chronic lung diseases and ageing

Growth differentiation factor 15 (GDF15), a member of the transforming growth factor-beta superfamily, is expressed in several human organs. In particular, it is highly expressed in the placenta, prostate, and liver. The expression of GDF15 increases under cellular stress and pathological conditions. Although numerous transcription factors directly up-regulate the expression of GDF15, the receptors and downstream mediators of GDF15 signal transduction in most tissues have not yet been determined. Glial cell-derived neurotrophic factor family receptor α-like protein was recently identified as a specific receptor that plays a mediating role in anorexia. However, the specific receptors of GDF15 in other tissues and organs remain unclear. As a marker of cell stress, GDF15 appears to exert different effects under different pathological conditions. Cell senescence may be an important pathogenetic process and could be used to assess the progression of various lung diseases, including COVID-19. As a key member of the senescence-associated secretory phenotype protein repertoire, GDF15 seems to be associated with mitochondrial dysfunction, although the specific molecular mechanism linking GDF15 expression with ageing remains to be elucidated. Here, we focus on research progress linking GDF15 expression with the pathogenesis of various chronic lung diseases, including neonatal bronchopulmonary dysplasia, idiopathic pulmonary fibrosis, chronic obstructive pulmonary disease, and pulmonary hypertension, suggesting that GDF15 may be a key biomarker for diagnosis and prognosis. Thus, in this review, we aimed to provide new insights into the molecular biological mechanism and emerging clinical data associated with GDF15 in lung-related diseases, while highlighting promising research and clinical prospects.

Association of growth and differentiation factor-15 with coronary artery calcium score and ankle-brachial index in a middle-aged and elderly Caucasian population sample free of manifest cardiovascular disease

Growth and differentiation factor-15 (GDF-15) is a stress-associated cytokine of the transforming growth factor-β superfamily. The inflammatory and angiogenic effects of GDF-15 in atherosclerosis are controversial, and its correlation with the long asymptomatic phase of the disease is not well understood. Coronary artery calcium score (CACS) and ankle-brachial index (ABI) are sensitive markers of subclinical atherosclerosis. To date, only a few studies have examined the impact of GDF-15 on coronary artery calcification, and the association between GDF-15 and ABI has not been evaluated. Therefore, we aimed to investigate the possible relationship between serum GDF-15 concentrations and CACS and ABI in a Caucasian population sample of middle-aged (35-65 years) and elderly (> 65 years) people. In addition to recording demographic and anthropometric characteristics, atherosclerotic risk factors, and laboratory tests including serum HDL-cholesterol, LDL-cholesterol, hemoglobin A1c (HbA1c), high-sensitivity C-reactive protein, and N-terminal pro-B-type natriuretic peptide (NT-proBNP); GDF-15 level, cardiac computed tomography, and ABI measurements were also performed. A total of 269 asymptomatic individuals (men, n = 125; median age, 61.5 [IQR, 12.7] years) formed the basis of this study. Participants were divided into two groups according to their age (middle-aged, n = 175 and elderly, n = 94). Hypertension and diabetes mellitus were significantly more prevalent and CACS values and HbA1c, NT-proBNP, and GDF-15 levels were significantly higher (all p < 0.001) in the elderly group compared to the middle-aged group. Multivariate ridge regression analysis revealed a significant positive association between GDF-15 and CACS (middle-aged group: β = 0.072, p = 0.333; elderly group: β = 0.148, p = 0.003), and between GDF-15 and ABI (middle-aged group: β = 0.062, p = 0.393; elderly group: β = 0.088, p = 0.041) only in the elderly group. Our results show that GDF-15 is not only a useful biomarker of inflammation but can also predict early signs of asymptomatic atherosclerosis, especially in elderly people with chronic systemic inflammation associated with aging (inflammaging).

Growth differentiation factor-15 in patients with or at risk of heart failure but before first hospitalisation

OBJECTIVE

Identification of patients at risk of adverse outcome from heart failure (HF) at an early stage is a priority. Growth differentiation factor (GDF)-15 has emerged as a potentially useful biomarker. This study sought to identify determinants of circulating GDF-15 and evaluate its prognostic value, in patients at risk of HF or with HF but before first hospitalisation.

METHODS

Prospective, longitudinal cohort study of 2166 consecutive patients in stage A-C HF undergoing cardiovascular magnetic resonance and measurement of GDF-15. Multivariable linear regression investigated determinants of GDF-15. Cox proportional hazards modelling, Net Reclassification Improvement and decision curve analysis examined its incremental prognostic value. Primary outcome was a composite of first hospitalisation for HF or all-cause mortality. Median follow-up was 1093 (939-1231) days.

RESULTS

Major determinants of GDF-15 were age, diabetes and N-terminal pro-B-type natriuretic peptide, although despite extensive phenotyping, only around half of the variability of GDF-15 could be explained (R2 0.51). Log-transformed GDF-15 was the strongest predictor of outcome (HR 2.12, 95% CI 1.71 to 2.63) and resulted in a risk prediction model with higher predictive accuracy (continuous Net Reclassification Improvement 0.26; 95% CI 0.13 to 0.39) and with greater clinical net benefit across the entire range of threshold probabilities.

CONCLUSION

In patients at risk of HF, or with HF but before first hospitalisation, GDF-15 provides unique information and is highly predictive of hospitalisation for HF or all-cause mortality, leading to more accurate risk stratification that can improve clinical decision making.

TRIAL REGISTRATION NUMBER

NCT02326324.

Research progress of plant-derived natural products in thyroid carcinoma

Thyroid carcinoma (TC) is a prevalent malignancy of the endocrine system, with a notable rise in its detection rate in recent decades. The primary therapeutic approaches for TC now encompass thyroidectomy and radioactive iodine therapy, yielding favorable prognoses for the majority of patients. TC survivors may necessitate ongoing surveillance, remedial treatment, and thyroid hormone supplementation, while also enduring the adverse consequences of thyroid hormone fluctuations, surgical complications, or side effects linked to radioactive iodine administration, and encountering enduring physical, psychosocial, and economic hardships. In vitro and in vivo studies of natural products against TC are demonstrating the potential of these natural products as alternatives to the treatment of thyroid cancer. This therapy may offer greater convenience, affordability, and acceptability than traditional therapies. In the early screening of natural products, we mainly use a combination of database prediction and literature search. The pharmacological effects on TC of selected natural products (quercetin, genistein, apigenin, luteolin, chrysin, myricetin, resveratrol, curcumin and nobiletin), which hold promise for therapeutic applications in TC, are reviewed in detail in this article through most of the cell-level evidence, animal-level evidence, and a small amount of human-level evidence. In addition, this article explores possible issues, such as bioavailability, drug safety.

GDF15 Protects Insulin-Producing Beta Cells against Pro-Inflammatory Cytokines and Metabolic Stress via Increased Deamination of Intracellular Adenosine

It has been proposed that antidiabetic drugs, such as metformin and imatinib, at least in part, promote improved glucose tolerance in type 2 diabetic patients via increased production of the inflammatory cytokine GDF15. This is supported by studies, performed in rodent cell lines and mouse models, in which the addition or production of GDF15 improved beta-cell function and survival. The aim of the present study was to determine whether human beta cells produce GDF15 in response to antidiabetic drugs and, if so, to further elucidate the mechanisms by which GDF15 modulates the function and survival of such cells. The effects and expression of GDF15 were analyzed in human insulin-producing EndoC-betaH1 cells and human islets. We observed that alpha and beta cells exhibit considerable heterogeneity in GDF15 immuno-positivity. The predominant form of GDF15 present in islet and EndoC-betaH1 cells was pro-GDF15. Imatinib, but not metformin, increased pro-GDF15 levels in EndoC-betaH1 cells. Under basal conditions, exogenous GDF15 increased human islet oxygen consumption rates. In EndoC-betaH1 cells and human islets, exogenous GDF15 partially ameliorated cytokine- or palmitate + high-glucose-induced loss of function and viability. GDF15-induced cell survival was paralleled by increased inosine levels, suggesting a more efficient disposal of intracellular adenosine. Knockdown of adenosine deaminase, the enzyme that converts adenosine to inosine, resulted in lowered inosine levels and loss of protection against cytokine- or palmitate + high-glucose-induced cell death. It is concluded that imatinib-induced GDF15 production may protect human beta cells partially against inflammatory and metabolic stress. Furthermore, it is possible that the GDF15-mediated activation of adenosine deaminase and the increased disposal of intracellular adenosine participate in protection against beta-cell death.

Relation of Sleep Quality to a Panel of Plasma Cardiometabolic Markers in Airline Pilots: A Cross-Sectional Study

Background Insomnia and poor sleep are leading modifiable risk factors for cardiovascular disease. Given the high susceptibility of airline pilots (APs) to sleep disturbances, we sought to investigate the hypothesis that poor sleep in this professional group correlates with alterations in plasma biochemical markers that would reflect critical aspects in the pathophysiology of cardiometabolic disorders. Methods In this preliminary cross-sectional study, we examined the relation of poor sleep to fourteen plasma biomarkers reflecting multiple cardiometabolic pathways in a convenience sample of 117 male APs. The Pittsburgh Sleep Quality Index (PSQI) was used to categorize the participants into good sleepers (n = 70, 59.8%; PSQI scores from 0 to 4) and poor sleepers (n = 47, 40.2%; PSQI scores of 5 or higher). The concentrations of biomarkers were compared between the two groups using both univariable and multivariable analyses. Results Compared to good sleepers, APs identified as poor sleepers exhibited significantly different levels of four plasma cardiometabolic biochemical markers in univariable analysis. However, in multivariable-adjusted analysis, only three biomarkers, adiponectin, fibroblast growth factor (FGF)-21, and growth differentiation factor (GDF)-15, remained independently associated with poor sleep. Conclusion Poor sleep quality in APs correlates with lower plasma concentrations of adiponectin and elevated levels of FGF-21 and GDF-15. Further longitudinal studies are required to elucidate the role of these biomarkers in the link between sleep disturbances and cardiometabolic risk in this professional group.

GB18-06, a nanobody targeting GDF15, effectively alleviates weight loss and restores physical function in cachexia models

Cachexia is a complicated metabolic syndrome mainly associated with cancers, characterized by extreme weight loss and muscle wasting. It is a debilitating condition that negatively affects prognosis and survival. However, there is currently no effective pharmacological intervention that can reverse body weight loss and improve physical performance in patients with cachexia. Growth differentiation factor 15 (GDF15) can suppress appetite and regulate energy balance through binding to glial cell-derived neurotrophic factor receptor alpha-like (GFRAL). In order to develop a novel, effective treatment for cachexia, we generated a GDF15-targeting VHH nanobody, GB18-06, that was able to bind GDF15 with high affinity. In vitro, GB18-06 potently inhibited the GDF15-GFRAL signaling pathway, leading to a reduction of downstream ERK and AKT phosphorylation levels; in vivo, GB18-06 alleviated weight loss (>20%) in cancer and chemotherapy-induced cachexia models in mice. Compared with the control (phosphate-buffered saline) group, the ambulatory activity of mice in the GB18-06-treated group also increased 77%. Furthermore, GB18-06 exhibited desirable pharmacokinetic properties and an excellent developability profile. Our study has demonstrated a means of developing targeted treatment for cachexia with high efficacy, potentially leading to improved clinical outcomes and quality of life for patients with cachexia.

Protein biomarkers GDF15 and FGF21 to differentiate mitochondrial hepatopathies from other pediatric liver diseases

BACKGROUND

Mitochondrial hepatopathies (MHs) are primary mitochondrial genetic disorders that can present as childhood liver disease. No recognized biomarkers discriminate MH from other childhood liver diseases. The protein biomarkers growth differentiation factor 15 (GDF15) and fibroblast growth factor 21 (FGF21) differentiate mitochondrial myopathies from other myopathies. We evaluated these biomarkers to determine if they discriminate MH from other liver diseases in children.

METHODS

Serum biomarkers were measured in 36 children with MH (17 had a genetic diagnosis); 38 each with biliary atresia, α1-antitrypsin deficiency, and Alagille syndrome; 20 with NASH; and 186 controls.

RESULTS

GDF15 levels compared to controls were mildly elevated in patients with α1-antitrypsin deficiency, Alagille syndrome, and biliary atresia-young subgroup, but markedly elevated in MH (p<0.001). FGF21 levels were mildly elevated in NASH and markedly elevated in MH (p<0.001). Both biomarkers were higher in patients with MH with a known genetic cause but were similar in acute and chronic presentations. Both markers had a strong performance to identify MH with a molecular diagnosis with the AUC for GDF15 0.93±0.04 and for FGF21 0.90±0.06. Simultaneous elevation of both markers >98th percentile of controls identified genetically confirmed MH with a sensitivity of 88% and specificity of 96%. In MH, independent predictors of survival without requiring liver transplantation were international normalized ratio and either GDF15 or FGF21 levels, with levels <2000 ng/L predicting survival without liver transplantation (p<0.01).

CONCLUSIONS

GDF15 and FGF21 are significantly higher in children with MH compared to other childhood liver diseases and controls and, when combined, were predictive of MH and had prognostic implications.

Implication of serum growth differentiation factor-15 level in patients with renal diseases

BACKGROUND

The synthesis of growth differentiation factor-15 (GDF-15) is induced by inflammation, hypoxia, and oxidative stress and is receiving great interest as a predictive biomarker for cardiovascular disease. However, its detailed impact on patients with renal disease remains uncertain.

METHODS

Patients who underwent renal biopsy for evaluation of renal disease between 2012 and 2017 in our institute were prospectively included. Serum GDF-15 levels were measured and its association with baseline characteristics and its impact on the 3-year composites of renal prognosis (composites of > 1.5 folds of serum creatinine and renal replacement therapy) were investigated.

RESULTS

A total of 110 patients (64 [42, 73] years old, 61 men) were included. The median serum GDF-15 level at baseline was 1885 (998, 3496) pg/mL. A higher serum GDF-15 level was associated with comorbidities including diabetes mellitus, anemia, renal impairment, and pathologic features including crescent formation, hyaline degeneration, and interstitial fibrosis (p < 0.05 for all). Serum GDF-15 level was a significant predictor of 3-year composite renal outcomes with an odds ratio per 100 pg/mL of 1.072 (95% confidence interval 1.001-1.103, p = 0.036) after adjustment for potential confounders.

CONCLUSIONS

Serum GDF-15 levels were associated with several renal pathological features and renal prognosis in patients with renal diseases.

GDF15 is required for cold-induced thermogenesis and contributes to improved systemic metabolic health following loss of OPA1 in brown adipocytes

We previously reported that mice lacking the protein optic atrophy 1 (OPA1 BKO) in brown adipose tissue (BAT) display induction of the activating transcription factor 4 (ATF4), which promotes fibroblast growth factor 21 (FGF21) secretion as a batokine. FGF21 increases metabolic rates under baseline conditions but is dispensable for the resistance to diet-induced obesity (DIO) reported in OPA1 BKO mice (Pereira et al., 2021). To determine alternative mediators of this phenotype, we performed transcriptome analysis, which revealed increased levels of growth differentiation factor 15 (GDF15), along with increased protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK) levels in BAT. To investigate whether ATF4 induction was mediated by PERK and evaluate the contribution of GDF15 to the resistance to DIO, we selectively deleted PERK or GDF15 in OPA1 BKO mice. Mice with reduced OPA1 and PERK levels in BAT had preserved ISR activation. Importantly, simultaneous deletion of OPA1 and GDF15 partially reversed the resistance to DIO and abrogated the improvements in glucose tolerance. Furthermore, GDF15 was required to improve cold-induced thermogenesis in OPA1 BKO mice. Taken together, our data indicate that PERK is dispensable to induce the ISR, but GDF15 contributes to the resistance to DIO, and is required for glucose homeostasis and thermoregulation in OPA1 BKO mice by increasing energy expenditure.

Transcriptomic characterization of classical monocytes highlights the involvement of immuno-inflammation in bone erosion in Rheumatoid Arthritis

Introduction

Evidence-based data suggest that under inflammatory conditions, classical monocytes are the main source of osteoclasts and might be involved in bone erosion pathophysiology. Here, we analyze the transcriptomic profile of classical monocytes in erosive and non-erosive rheumatoid arthritis patients in order to better understand their contribution to bone erosion.

Methods

Thirty-nine premenopausal RA patients were consecutively enrolled and divided into two groups based on the presence of bone erosions on hand joints. Classical monocytes were isolated from peripheral blood through negative selection, and RNA-seq was performed using a poly-A enrichment kit and Illumina® platform. Classical monocytes transcriptome from healthy age-matched women were also included to identify differentially expressed genes (DEGs). Therefore, gene sets analysis was performed to identify the enriched biological pathways.

Results

RNA-seq analysis resulted in the identification of 1,140 DEGs of which 89 were up-regulated and 1,051 down-regulated in RA patients with bone erosion compared to those without bone erosions. Among up-regulated genes, there was a highlighted expression of IL18RAP and KLF14 related to the production of pro-inflammatory cytokines, innate and adaptive immune response. Genes related to collagen metabolism (LARP6) and bone formation process (PAPPA) were down-regulated in RA patients with erosions. Enriched pathways in patients with erosions were associated with greater activation of immune activation, and inflammation. Interestingly, pathways associated with osteoblast differentiation and regulation of Wnt signaling were less activated in RA patients with erosions.

Conclusion

These findings suggest that alterations in expression of monocyte genes related to the inflammatory process and impairment of bone formation might have an important role in the pathophysiology of bone erosions in RA patients.

The roles of FGF21 and GDF15 in mediating the mitochondrial integrated stress response

Various models of mitochondrial stress result in induction of the stress-responsive cytokines fibroblast growth factor 21 (FGF21) and growth differentiation factor 15 (GDF15). This is an adaptive mechanism downstream of the mitochondrial integrated stress response frequently associated with improvements in systemic metabolic health. Both FGF21 and GDF15 have been shown to modulate energy balance and glucose homeostasis, and their pharmacological administration leads to promising beneficial effects against obesity and associated metabolic diseases in pre-clinical models. Furthermore, endogenous upregulation of FGF21 and GDF15 is associated with resistance to diet-induced obesity (DIO), improved glucose homeostasis and increased insulin sensitivity. In this review, we highlight several studies on transgenic mouse models of mitochondrial stress and will compare the specific roles played by FGF21 and GDF15 on the systemic metabolic adaptations reported in these models.

Growth differentiation factor 15 (GDF-15) in endocrinology

Human growth differentiation factor 15 (GDF-15) is a widely distributed protein that has shown to play multiple roles in both physiological and pathological conditions. In healthy individuals, GDF-15 is mainly expressed in the placenta, followed by the prostate, although low levels of expression have also been detected in different organs. GDF-15 acts through a recently identified receptor called glial-derived neurotrophic factor (GDNF) receptor alpha-like (GFRAL) which signals through the rearranged during transfection (RET) tyrosine kinase receptor. The effects of GDF-15 are pleiotropic and include appetite regulation, and actions on metabolism, pregnancy, cell survival, immune response, and inflammation. GDF-15 also plays different roles in the pathophysiology of cardiovascular disease, autoimmunity, cancer-associated anorexia/cachexia, and diabetes. In recent years, several studies have reported a link between GDF-15 and the endocrine system. In this review, we up-date and summarize the relevant investigations of the relationships between GDF-15 and different endocrine conditions. We also assess the potential pathogenic role and potential therapeutic applications of GDF-15 in the field of endocrinology.

Proteomic basis of mortality resilience mediated by FOXO3 longevity genotype

FOXO3 is a ubiquitous transcription factor expressed in response to cellular stress caused by nutrient deprivation, inflammatory cytokines, reactive oxygen species, radiation, hypoxia, and other factors. We showed previously that the association of inherited FOXO3 variants with longevity was the result of partial protection against mortality risk posed by aging-related life-long stressors, particularly cardiometabolic disease. We then referred to the longevity-associated genotypes as conferring "mortality resilience." Serum proteins whose levels change with aging and are associated with mortality risk may be considered as "stress proteins." They may serve as indirect measures of life-long stress. Our aims were to (1) identify stress proteins that increase with aging and are associated with an increased risk of mortality, and (2) to determine if FOXO3 longevity/resilience genotype dampens the expected increase in mortality risk they pose. A total of 4500 serum protein aptamers were quantified using the Somalogic SomaScan proteomics platform in the current study of 975 men aged 71-83 years. Stress proteins associated with mortality were identified. We then used age-adjusted multivariable Cox models to investigate the interaction of stress protein with FOXO3 longevity-associated rs12212067 genotypes. For all the analyses, the p values were corrected for multiple comparisons by false discovery rate. This led to the identification of 44 stress proteins influencing the association of FOXO3 genotype with reduced mortality. Biological pathways were identified for these proteins. Our results suggest that the FOXO3 resilience genotype functions by reducing mortality in pathways related to innate immunity, bone morphogenetic protein signaling, leukocyte migration, and growth factor response.

Growth Differentiation Factor 15 and Clinical Outcomes in Japanese Patients With Heart Failure

BACKGROUND

Heart failure (HF) is an increasing health problem associated with a high mortality rate. Growth differentiation factor (GDF) 15, a stress response cytokine belonging to the transforming growth factor-β superfamily, is associated with poor clinical outcomes in a broad spectrum of cardiovascular diseases. However, the prognostic usefulness of GDF15 in Japanese patients with HF remains unclear.

METHODS AND RESULTS

We measured serum concentrations of GDF15 and B-type natriuretic peptide (BNP) in 1,201 patients with HF. All patients were prospectively followed for a median period of 1,309 days. In all, 319 HF-related events and 187 all-cause deaths occurred during the follow-up period. Kaplan-Meier analysis demonstrated that, among GDF15 tertiles, the highest tertile group had the greatest risk of HF-related events and all-cause mortality. Multivariate Cox proportional hazard regression analysis demonstrated that the serum GDF15 concentration was an independent predictor of HF-related events and all-cause deaths after adjusting for confounding risk factors. Serum GDF15 improved the prediction capacity for all-cause deaths and HF-related events with a significant net reclassification index and integrated discrimination improvement. Subgroup analysis in patients with HF with preserved ejection fraction also showed the prognostic usefulness of GDF15.

CONCLUSIONS

Serum GDF15 concentrations were associated with HF severity and clinical outcomes, indicating that GDF15 could provide additional clinical information to track the health status of patients with HF.

Biomarkers to predict disease progression and therapeutic response in isolated methylmalonic acidemia

Methylmalonic Acidemia (MMA) is a heterogenous group of inborn errors of metabolism caused by a defect in the methylmalonyl-CoA mutase (MMUT) enzyme or the synthesis and transport of its cofactor, 5'-deoxy-adenosylcobalamin. It is characterized by life-threatening episodes of ketoacidosis, chronic kidney disease, and other multiorgan complications. Liver transplantation can improve patient stability and survival and thus provides clinical and biochemical benchmarks for the development of hepatocyte-targeted genomic therapies. Data are presented from a US natural history protocol that evaluated subjects with different types of MMA including mut-type (N = 91), cblB-type (15), and cblA-type MMA (17), as well as from an Italian cohort of mut-type (N = 19) and cblB-type MMA (N = 2) subjects, including data before and after organ transplantation in both cohorts. Canonical metabolic markers, such as serum methylmalonic acid and propionylcarnitine, are variable and affected by dietary intake and renal function. We have therefore explored the use of the 1-13 C-propionate oxidation breath test (POBT) to measure metabolic capacity and the changes in circulating proteins to assess mitochondrial dysfunction (fibroblast growth factor 21 [FGF21] and growth differentiation factor 15 [GDF15]) and kidney injury (lipocalin-2 [LCN2]). Biomarker concentrations are higher in patients with the severe mut0 -type and cblB-type MMA, correlate with a decreased POBT, and show a significant response postliver transplant. Additional circulating and imaging markers to assess disease burden are necessary to monitor disease progression. A combination of biomarkers reflecting disease severity and multisystem involvement will be needed to help stratify patients for clinical trials and assess the efficacy of new therapies for MMA.