Obesity and low-grade inflammation increase plasma follistatin-like 3 in humans

Proteomic Correlates and Prognostic Significance of Kidney Injury in Heart Failure With Preserved Ejection Fraction

BACKGROUND

Kidney disease is common in heart failure with preserved ejection fraction (HFpEF). However, the biologic correlates and prognostic significance of kidney injury (KI), in HFpEF, beyond the estimated glomerular filtration rate (eGFR), are unclear.

METHODS AND RESULTS

Using baseline plasma samples from the TOPCAT (Treatment of Preserved Cardiac Function Heart Failure With an Aldosterone Antagonist) trial, we measured the following KI biomarkers: cystatin-C, fatty acid-binding protein-3, Beta-2 microglobulin, neutrophil gelatinase-associated lipocalin, and kidney-injury molecule-1. Factor analysis was used to extract the common variability underlying these biomarkers. We assessed the relationship between the KI-factor score and the risk of death or HF-related hospital admission in models adjusted for the Meta-Analysis Global Group in Chronic Heart Failure risk score and eGFR. We also assessed the relationship between the KI factor score and ~5000 plasma proteins, followed by pathway analysis. We validated our findings among HFpEF participants in the Penn Heart Failure Study. KI was associated with the risk of death or HF-related hospital admission independent of the Meta-Analysis Global Group in Chronic Heart Failure risk score and eGFR. Both the risk score and eGFR were no longer associated with death or HF-related hospital admission after adjusting for the KI factor score. KI was predominantly associated with proteins and biologic pathways related to complement activation, inflammation, fibrosis, and cholesterol homeostasis. KI was associated with 140 proteins, which reproduced across cohorts. Findings regarding biologic associations and the prognostic significance of KI were also reproduced in the validation cohort.

CONCLUSIONS

KI is associated with adverse outcomes in HFpEF independent of baseline eGFR. Patients with HFpEF and KI exhibit a plasma proteomic signature indicative of complement activation, inflammation, fibrosis, and impaired cholesterol homeostasis.

FSTL3 is associated with prognosis and immune cell infiltration in lung adenocarcinoma

PURPOSE

FSTL3 expression is altered in various types of cancer. However, the role and mechanism of action of FSTL3 in lung adenocarcinoma development and tumor immunity are unknown. We investigated the association between FSTL3 expression and clinical characteristics and immune cell infiltration in lung adenocarcinoma samples from The Cancer Genome Atlas (TCGA) and a separate validation set from our hospital.

METHODS

Data on immune system infiltration, gene expression, and relevant clinical information were obtained by analyzing lung adenocarcinoma sample data from TCGA database. Using online tools like GEPIA, the correlations between FSTL3 expression and prognosis, clinical stage, survival status, and tumor-infiltrating immune cells were examined. In a validation dataset, immunohistochemistry was performed to analyze FSTL3 expression and its related clinical characteristics.

RESULTS

FSTL3 expression was markedly reduced in patients with lung adenocarcinoma. N stage, pathological stage, and overall survival were significantly correlated with FSTL3 expression. According to GSEA, FSTL3 is strongly linked to signaling pathways such as DNA replication and those involved in cell cycle regulation. Examination of TCGA database and TIMER online revealed a correlation between FSTL3 and B cell, T cell, NK cell, and neutrophil levels. The prognosis of patients with lung adenocarcinoma was significantly affected by six genes (KRT6A, VEGFC, KRT14, KRT17, SNORA12, and KRT81) related to FSTL3.

CONCLUSION

FSTL3 is significantly associated with the prognosis and progression of lung adenocarcinoma and the infiltration of immune cells. Thus, targeting FSTL3 and its associated genes in immunotherapy could be potentially beneficial for the treatment of lung adenocarcinoma.

Circulating Growth Differentiation Factors 11 and 8, Their Antagonists Follistatin and Follistatin-Like-3, and Risk of Heart Failure in Elders

BACKGROUND

Heterochronic parabiosis has identified growth differentiation factor (GDF)-11 as a potential means of cardiac rejuvenation, but findings have been inconsistent. A major barrier has been lack of assay specificity for GDF-11 and its homolog GDF-8.

METHODS

We tested the hypothesis that GDF-11 and GDF-8, and their major antagonists follistatin and follistatin-like (FSTL)-3, are associated with incident heart failure (HF) and its subtypes in elders. Based on validation experiments, we used liquid chromatography-tandem mass spectrometry to measure total serum GDF-11 and GDF-8, along with follistatin and FSTL-3 by immunoassay, in 2 longitudinal cohorts of older adults.

RESULTS

In 2 599 participants (age 75.2 ± 4.3) followed for 10.8 ± 5.6 years, 721 HF events occurred. After adjustment, neither GDF-11 (HR per doubling: 0.93 [0.67, 1.30]) nor GDF-8 (HR: 1.02 per doubling [0.83, 1.27]) was associated with incident HF or its subtypes. Positive associations with HF were detected for follistatin (HR: 1.15 [1.00, 1.32]) and FLST-3 (HR: 1.38 [1.03, 1.85]), and with HF with preserved ejection fraction for FSTL-3 (HR: 1.77 [1.03, 3.02]). (All HRs per doubling of biomarker.) FSTL-3 associations with HF appeared stronger at higher follistatin levels and vice versa, and also for men, Blacks, and lower kidney function.

CONCLUSIONS

Among older adults, serum follistatin and FSTL-3, but not GDF-11 or GDF-8, were associated with incident HF. These findings do not support the concept that low serum levels of total GDF-11 or GDF-8 contribute to HF late in life, but do implicate transforming growth factor-β superfamily pathways as potential therapeutic targets.

Follistatin and follistatin-like 3 in metabolic disorders

Follistatin (FST) is a glycoprotein which main role is antagonizing activity of transforming growth factor β superfamily members. Folistatin-related proteins such as follistatin-like 3 (FSTL3) also reveal these properties. The exact function of them has still not been established, but it can be bound to the pathogenesis of metabolic disorders. So far, there were performed a few studies about their role in type 2 diabetes, obesity or gestational diabetes and even less in type 1 diabetes. The outcomes are contradictory and do not allow to draw exact conclusions. In this article we summarize the available information about connections between follistatin, as well as follistatin-like 3, and metabolic disorders. We also emphasize the strong need of performing further research to explain their exact role, especially in the pathogenesis of diabetes and obesity.

FSTL3 is highly expressed in adipose tissue of individuals with overweight or obesity and is associated with inflammation

OBJECTIVE

This study aimed to investigate the expression of follistatin-like 3 (FSTL3) in adipose tissue in individuals with overweight or obesity and to explore the role of FSTL3 in human adipocytes, as well as the relationship between serum FSTL3 levels and fat distribution and inflammation.

METHODS

This study enrolled 236 individuals (171 with overweight or obesity; aged 18-67 years). Bulk transcriptome sequencing was performed on subcutaneous and visceral adipose tissue. The function of FSTL3 was studied in human adipocytes. Serum FSTL3 levels were measured using enzyme-linked immunosorbent assay.

RESULTS

Adipose FTSL3 expression was higher in individuals with overweight or obesity than in individuals with normal weight. FSTL3 was mainly expressed in mature adipocytes and stimulated by tumor necrosis factor alpha (TNFα). FSTL3 suppressed inflammatory responses in human adipocytes, whereas FSTL3 knockdown promoted inflammatory responses. Serum FSTL3 levels were correlated with adipose FTSL3 expression and obesity-related indicators (all p < 0.05). Multiple linear regression analysis showed that serum FSTL3 levels were independently associated with the visceral fat area and serum TNFα levels (both p < 0.05).

CONCLUSIONS

FSTL3 was highly expressed in adipose tissue in individuals with overweight or obesity and could suppress adipocyte inflammation. Serum FSTL3 levels might be considered as a biomarker of visceral obesity and inflammation.

Roles of follistatin-like protein 3 in human non-tumor pathophysiologies and cancers

Follistatin-like protein 3 (FSTL3) is a type of FSTLs. By interacting with a disintegrin and metalloproteinase 12 (ADAM12), transforming growth factor-β ligands (activin, myostatin and growth differentiation factor (GDF) 11), FSTL3 can either activate or inhibit these molecules in human non-tumor pathophysiologies and cancers. The FSTL3 gene was initially discovered in patients with in B-cell chronic lymphocytic leukemia, and subsequent studies have shown that the FSTL3 protein is associated with reproductive development, insulin resistance, and hematopoiesis. FSTL3 reportedly contributes to the development and progression of many cancers by promoting tumor metastasis, facilitating angiogenesis, and inducing stem cell differentiation. This review summarizes the current pathophysiological roles of FSTL3, which may be a putative prognostic biomarker for various diseases and serve as a potential therapeutic target.

Can Exercise Training Alter Human Skeletal Muscle DNA Methylation?

Skeletal muscle is highly plastic and dynamically regulated by the body’s physical demands. This study aimed to determine the plasticity of skeletal muscle DNA methylation in response to 8 weeks of supervised exercise training in volunteers with a range of insulin sensitivities. We studied 13 sedentary participants and performed euglycemic hyperinsulinemic clamps with basal vastus lateralis muscle biopsies and peak aerobic activity (VO2 peak) tests before and after training. We extracted DNA from the muscle biopsies and performed global methylation using Illumina’s Methylation EPIC 850K BeadChip. Training significantly increased peak aerobic capacity and insulin-stimulated glucose disposal. Fasting serum insulin and insulin levels during the steady state of the clamp were significantly lower post-training. Insulin clearance rates during the clamp increased following the training. We identified 13 increased and 90 decreased differentially methylated cytosines (DMCs) in response to 8 weeks of training. Of the 13 increased DMCs, 2 were within the following genes, FSTL3, and RP11-624M8.1. Of the 90 decreased DMCs, 9 were within the genes CNGA1, FCGR2A, KIF21A, MEIS1, NT5DC1, OR4D1, PRPF4B, SLC26A7, and ZNF280C. Moreover, pathway analysis showed an enrichment in metabolic and actin-cytoskeleton pathways for the decreased DMCs, and for the increased DMCs, an enrichment in signal-dependent regulation of myogenesis, NOTCH2 activation and transmission, and SMAD2/3: SMAD4 transcriptional activity pathways. Our findings showed that 8 weeks of exercise training alters skeletal muscle DNA methylation of specific genes and pathways in people with varying degrees of insulin sensitivity.

Follistatin-Like Proteins: Structure, Functions and Biomedical Importance

Main forms of cellular signal transmission are known to be autocrine and paracrine signaling. Several cells secrete messengers called autocrine or paracrine agents that can bind the corresponding receptors on the surface of the cells themselves or their microenvironment. Follistatin and follistatin-like proteins can be called one of the most important bifunctional messengers capable of displaying both autocrine and paracrine activity. Whilst they are not as diverse as protein hormones or protein kinases, there are only five types of proteins. However, unlike protein kinases, there are no minor proteins among them; each follistatin-like protein performs an important physiological function. These proteins are involved in a variety of signaling pathways and biological processes, having the ability to bind to receptors such as DIP2A, TLR4, BMP and some others. The activation or experimentally induced knockout of the protein-coding genes often leads to fatal consequences for individual cells and the whole body as follistatin-like proteins indirectly regulate the cell cycle, tissue differentiation, metabolic pathways, and participate in the transmission chains of the pro-inflammatory intracellular signal. Abnormal course of these processes can cause the development of oncology or apoptosis, programmed cell death. There is still no comprehensive understanding of the spectrum of mechanisms of action of follistatin-like proteins, so the systematization and study of their cellular functions and regulation is an important direction of modern molecular and cell biology. Therefore, this review focuses on follistatin-related proteins that affect multiple targets and have direct or indirect effects on cellular signaling pathways, as well as to characterize the directions of their practical application in the field of biomedicine.

The RNA landscape of the human placenta in health and disease

The placenta is the interface between mother and fetus and inadequate function contributes to short and long-term ill-health. The placenta is absent from most large-scale RNA-Seq datasets. We therefore analyze long and small RNAs (~101 and 20 million reads per sample respectively) from 302 human placentas, including 94 cases of preeclampsia (PE) and 56 cases of fetal growth restriction (FGR). The placental transcriptome has the seventh lowest complexity of 50 human tissues: 271 genes account for 50% of all reads. We identify multiple circular RNAs and validate 6 of these by Sanger sequencing across the back-splice junction. Using large-scale mass spectrometry datasets, we find strong evidence of peptides produced by translation of two circular RNAs. We also identify novel piRNAs which are clustered on Chr1 and Chr14. PE and FGR are associated with multiple and overlapping differences in mRNA, lincRNA and circRNA but fewer consistent differences in small RNAs. Of the three protein coding genes differentially expressed in both PE and FGR, one encodes a secreted protein FSTL3 (follistatin-like 3). Elevated serum levels of FSTL3 in pregnant women are predictive of subsequent PE and FGR. To aid visualization of our placenta transcriptome data, we develop a web application ( https://www.obgyn.cam.ac.uk/placentome/ ).

Safety and tolerability of repeated sessions of deep transcranial magnetic stimulation in obesity

PURPOSE

Repetitive Transcranial Magnetic Stimulation (rTMS) has been demonstrated to be effective in body weight control in individuals with obesity. Most clinical trials on rTMS provided a reassuring safety profile. In the present work, we present an extensive analysis on both severe and mild Adverse Events (AEs) in obese individuals treated with rTMS.

METHODS

We examined the intensity, duration, correlation with the treatment, up to 1 year after the end of rTMS treatment.

RESULTS

Descriptive analysis included a total of 63 subjects undergoing a 5-week deep rTMS experimental treatment for obesity (age 48.3 ± 10.4 years; BMI 36.3 ± 4.4 kg/m²): 31 patients were treated with high-frequency rTMS (HF), 13 with low-frequency rTMS (LF), and 19 were sham treated (Sham). Thirty-two subjects (50.8%) reported a total of 52 AEs, including mainly moderate (51.9%) events. The most frequently reported side effects were headaches of moderate intensity (40.4%) and local pain/discomfort (19.2%) and resulted significantly more frequent in HF group compared to other groups (p < 0.05). No significant differences among groups were found for the other reported AEs: drowsiness, insomnia, paresthesia, vasovagal reactions, hypertensive crisis. No AEs potentially related to the rTMS arised up to 1 year from the end of the treatment.

CONCLUSIONS

This is the first comprehensive safety analysis in obese patients treated with rTMS. The analysis did not reveal any unexpected safety concerns. Only headaches and local pain/discomfort have been significantly more frequent in the HF group, confirming the good tolerability of rTMS even in the obese population potentially more susceptible to side effects of brain stimulation.

FSTL3 Induces Lipid Accumulation and Inflammatory Response in Macrophages and Associates With Atherosclerosis

FSTL3 as adipokine takes part in dyslipidemia and inflammatory response, but the association of FSTL3 with atherosclerosis is unclear. This study indicated that FSTL3 showed significantly higher level (control: 7.68 ± 3.10 vs. AS: 9.29 ± 2.37 ng/mL; P < 0.001) in atherosclerosis, and FSTL3 expressed higher in plaque of ApoE knockout mice and located in macrophages. Oxidized low-density lipoproteins induced expression and secretion of FSTL3, meanwhile FSTL3 promoted lipid accumulation in macrophages. The advanced study found that FSTL3 upregulated CD36 and LOX-1 expression in a dose-dependent manner; however, FSTL3 also evoked interleukin 1-β (IL1-β), monocyte chemoattractant protein 1 (MCP-1), tumor necrosis factor-α, and matrix metalloproteinase-9 (MMP-9) secretion in macrophages. On the contrary, that downregulated FSTL3 attenuated expression of oxidized low-density lipoproteins induced CD36, LOX-1, and inflammatory cytokines expressing. All of these results demonstrated that FSTL3 as a novelty cytokine takes part in the process of atherosclerosis through increasing lipid accumulation and inflammation through regulating CD36 and LOX-1 expression.

Galectin-3 Is Associated With Stage B Metabolic Heart Disease and Pulmonary Hypertension in Young Obese Patients

Background

Obesity is a precursor to heart failure with preserved ejection fraction. Biomarkers that identify preclinical metabolic heart disease (MHD) in young obese patients would help identify high‐risk individuals for heart failure prevention strategies. We assessed the predictive value of GAL3 (galectin–3), FSTL3 (follistatin‐like 3 peptide), and NT‐proBNP (N‐terminal pro‐B‐type natriuretic peptide) to identify stage B MHD in young obese participants free of clinically evident cardiovascular disease.

Methods and Results

Asymptomatic obese patients (n=250) and non‐obese controls (n=21) underwent echocardiographic cardiac phenotyping. Obese patients were classified as MHD positive (MHD‐POS; n=94) if they had abnormal diastolic function or left ventricular hypertrophy and had estimated pulmonary artery systolic pressure ≥35 mm Hg. Obese patients without such abnormalities were classified as MHD negative (MHD‐NEG; n=52). Serum biomarkers timed with echocardiography. MHD‐POS and MHD‐NEG individuals were similarly obese, but MHD‐POS patients were older, with more diabetes mellitus and metabolic syndrome. Right ventricular coupling was worse in MHD‐POS patients (P<0.001). GAL3 levels were higher in MHD‐POS versus MHD‐NEG patients (7.7±2.3 versus 6.3±1.9 ng/mL, respectively; P<0.001). Both GAL3 and FSTL3 levels correlated with diastolic dysfunction and increased pulmonary artery systolic pressure but not with left ventricular mass. In multivariate models including all 3 biomarkers, only GAL3 remained associated with MHD (odds ratio: 1.30; 95% CI, 1.01–1.68; P=0.04).

Conclusions

In young obese individuals without known cardiovascular disease, GAL3 is associated with the presence of preclinical MHD. GAL3 may be useful in screening for preclinical MHD and identifying individuals with increased risk of progression to obesity‐related heart failure with preserved ejection fraction.

Targeted Analysis of Three Hormonal Systems Identifies Molecules Associated with the Presence and Severity of NAFLD

AIMS

To investigate circulating levels and liver gene expression of 3 hormonal pathways associated with obesity, insulin resistance, and inflammation to identify leads towards potential diagnostic markers and therapeutic targets in patients with nonalcoholic fatty liver disease (NAFLD).

METHODS

We compared circulating levels of (1) proglucagon-derived hormones (glucagon-like peptide [GLP]-1, GLP-2, glicentin, oxyntomodulin, glucagon, major proglucagon fragment [MPGF]), (2) follistatins-activins (follistatin-like [FSTL]3, activin B), (3) IGF axis (insulin-like growth factor [IGF]-1, total and intact IGF binding protein [IGFBP]-3 and IGFBP-4, and pregnancy-associated plasma protein [PAPP]-A) in 2 studies: (1) 18 individuals with early stage NAFLD versus 14 controls (study 1; early NAFLD study) and in (2) 31 individuals with biopsy proven NAFLD (15 with simple steatosis [SS] and 16 with nonalcoholic steatohepatitis [NASH]), vs 50 controls (24 lean and 26 obese) (study 2). Liver gene expression was assessed in 22 subjects (12 controls, 5 NASH, 5 NASH-related cirrhosis).

RESULTS

Patients in early stages of NAFLD demonstrate higher fasting MPGF and lower incremental increase of glicentin during oral glucose tolerance test than controls. In more advanced stages, FSTL3 levels are higher in NASH than simple steatosis and, within NAFLD patients, in those with more severe lobular and portal inflammation. The IGF-1/intact IGFBP-3 ratio is lower in patients with liver fibrosis. Genes encoding follistatin, activin A, activin B, and the IGF-1 receptor are higher in NASH.

CONCLUSION

MPGF and glicentin may be involved in early stages of NAFLD, whereas FSTL3 and IGF-1/intact IGFBP3 in the progression to NASH and liver fibrosis respectively, suggesting potential as diagnostic markers or therapeutic targets.

Association of follistatin-like 3 concentrations in serum and synovial fluid with the radiographic severity of knee osteoarthritis

OBJECTIVE

Follistatin-like 3 (FSTL3), a circulating glycoprotein, is correlated with obesity and inflammation, which are potential mechanisms of osteoarthritis (OA). This study aims to determine the correlation of FSTL3 concentrations in serum and synovial fluid (SF) with the radiographic severity of OA.

METHODS

This study consisted of 200 patients with knee OA and 148 healthy controls. The radiological grading of OA in the knee was performed in accordance with Kellgren-Lawrence (KL) grading system.

RESULTS

Knee OA patients had higher serum FSTL3 concentrations compared with healthy controls. Knee OA patients with KL grade 4 showed significantly elevated FSTL3 concentrations in serum and SF compared with those with KL grades 2 and 3. Moreover, knee OA patients with KL grade 3 had significantly higher FSTL3 concentrations in serum and SF compared with those with KL grade 2. FSTL3 concentrations in serum and SF of knee OA patients were significantly correlated with KL grading criteria.

CONCLUSIONS

FSTL3 concentrations in serum and SF are correlated with the radiographic severity of OA.