Roles and Regulation of Growth differentiation factor-15 in the Immune and tumor microenvironment

Growth differentiation factor 15 as a potential diagnostic biomarker for rheumatoid arthritis : a systematic review

Aims

This systematic review aimed to investigate the association between growth differentiation factor 15 (GDF-15) and rheumatoid arthritis (RA) disease activity, explore the differences at the genetic level, and evaluate the value of GDF-15 in diagnosing RA.

Methods

A comprehensive literature search was conducted using PubMed, Web of Science, Cochrane Library, and Embase on 23 August 2023. Methodological quality was independently assessed by using the Agency for Healthcare Research and Quality scale. The primary parameters analyzed were the serum GDF-15 concentration, disease activity, and diagnostic sensitivity and specificity.

Results

A total of 469 documents were retrieved, and five clinical studies were ultimately included. In the included studies, GDF-15 serum levels were found to be notably greater in RA patients than in healthy individuals, and these levels exhibited a positive correlation with disease severity. Furthermore, increased GDF-15 serum levels were associated with specific gene variations in RA patients, but varied according to ethnicity. In two included studies, GDF-15 showed high diagnostic sensitivity and specificity for highly active RA, demonstrating its utility as a diagnostic biomarker of RA.

Conclusion

GDF-15 expression is increased in RA patients and is associated with disease activity; thus, GDF-15 is potentially an effective diagnostic biomarker for RA. However, additional high-quality studies, especially randomized controlled trials and cohort studies with follow-up data, are needed to assess the role of GDF-15 in RA.

GDNF family receptor alpha-like (GFRAL) expression is restricted to the caudal brainstem

OBJECTIVE

Growth differentiation factor 15 (GDF15) acts on the receptor dimer of GDNF family receptor alpha-like (GFRAL) and Rearranged during transfection (RET). While Gfral-expressing cells are known to be present in the area postrema and nucleus of the solitary tract (AP/NTS) located in the brainstem, the presence of Gfral-expressing cells in other sites within the central nervous system and peripheral tissues is not been fully addressed. Our objective was to thoroughly investigate whether GFRAL is expressed in peripheral tissues and in brain sites different from the brainstem.

METHODS

From Gfral:eGFP mice we collected tissue from 12 different tissues, including brain, and used single molecule in-situ hybridizations to identify cells within those tissues expressing Gfral. We then contrasted the results with human Gfral-expression by analyzing publicly available single-cell RNA sequencing data.

RESULTS

In mice we found readably detectable Gfral mRNA within the AP/NTS but not within other brain sites. Within peripheral tissues, we failed to detect any Gfral-labelled cells in the vast majority of examined tissues and when present, were extremely rare. Single cell sequencing of human tissues confirmed GFRAL-expressing cells are detectable in some sites outside the AP/NTS in an extremely sparse manner. Importantly, across the utilized methodologies, smFISH, genetic Gfral reporter mice and scRNA-Seq, we failed to detect Gfral-labelled cells with all three.

CONCLUSIONS

Through highly sensitive and selective technologies we show Gfral expression is overwhelmingly restricted to the brainstem and expect that GDF15 and GFRAL-based therapies in development for cancer cachexia will specifically target AP/NTS cells.

GDF15/MIC-1: a stress-induced immunosuppressive factor which promotes the aging process

The GDF15 protein, a member of the TGF-β superfamily, is a stress-induced multifunctional protein with many of its functions associated with the regulation of the immune system. GDF15 signaling provides a defence against the excessive inflammation induced by diverse stresses and tissue injuries. Given that the aging process is associated with a low-grade inflammatory state, called inflammaging, it is not surprising that the expression of GDF15 gradually increases with aging. In fact, the GDF15 protein is a core factor secreted by senescent cells, a state called senescence-associated secretory phenotype (SASP). Many age-related stresses, e.g., mitochondrial and endoplasmic reticulum stresses as well as inflammatory, metabolic, and oxidative stresses, induce the expression of GDF15. Although GDF15 signaling is an effective anti-inflammatory modulator, there is robust evidence that it is a pro-aging factor promoting the aging process. GDF15 signaling is not only an anti-inflammatory modulator but it is also a potent immunosuppressive enhancer in chronic inflammatory states. The GDF15 protein can stimulate immune responses either non-specifically via receptors of the TGF-β superfamily or specifically through the GFRAL/HPA/glucocorticoid pathway. GDF15 signaling stimulates the immunosuppressive network activating the functions of MDSCs, Tregs, and M2 macrophages and triggering inhibitory immune checkpoint signaling in senescent cells. Immunosuppressive responses not only suppress chronic inflammatory processes but they evoke many detrimental effects in aged tissues, such as cellular senescence, fibrosis, and tissue atrophy/sarcopenia. It seems that the survival functions of GDF15 go awry in persistent inflammation thus promoting the aging process and age-related diseases.

Bitter-tasting drugs tune GDF15 and GLP-1 expression via bitter taste or motilin receptors in the intestine of patients with obesity

OBJECTIVE

Growth differentiation factor 15 (GDF15), a stress related cytokine, was recently identified as a novel satiety signal acting via the GFRAL receptor located in the hindbrain. Bitter compounds are known to induce satiety via the release of glucagon-like peptide 1 (GLP-1) through activation of bitter taste receptors (TAS2Rs, 25 subtypes) on enteroendocrine cells in the gut. This study aimed to investigate whether and how bitter compounds induce a stress response in intestinal epithelial cells to affect GDF15 expression in patients with obesity, thereby facilitating satiety signaling from the gut.

METHODS

The acute effect of oral intake of the bitter-containing medication Plaquenil (hydroxychloroquine sulfate) on plasma GDF15 levels was evaluated in a placebo-controlled, double-blind, randomized, two-visit crossover study in healthy volunteers. Primary crypts isolated from the jejunal mucosa from patients with obesity were stimulated with vehicle or bitter compounds, and the effect on GDF15 expression was evaluated using RT-qPCR or ELISA. Immunofluorescence colocalization studies were performed between GDF15, epithelial cell type markers and TAS2Rs. The role of TAS2Rs was tested by 1) pretreatment with a TAS2R antagonist, GIV3727; 2) determining TAS2R4/43 polymorphisms that affect taste sensitivity to TAS2R4/43 agonists.

RESULTS

Acute intake of hydroxychloroquine sulfate increased GDF15 plasma levels, which correlated with reduced hunger scores and plasma ghrelin levels in healthy volunteers. This effect was mimicked in primary jejunal cultures from patients with obesity. GDF15 was expressed in enteroendocrine and goblet cells with higher expression levels in patients with obesity. Various bitter-tasting compounds (medicinal, plant extracts, bacterial) either increased or decreased GDF15 expression, with some also affecting GLP-1. The effect was mediated by specific intestinal TAS2R subtypes and the unfolded protein response pathway. The bitter-induced effect on GDF15/GLP-1 expression was influenced by the existence of TAS2R4 amino acid polymorphisms and TAS2R43 deletion polymorphisms that may predict patient's therapeutic responsiveness. However, the effect of the bitter-tasting antibiotic azithromycin on GDF15 release was mediated via the motilin receptor, possibly explaining some of its aversive side effects.

CONCLUSIONS

Bitter chemosensory and pharmacological receptors regulate the release of GDF15 from human gut epithelial cells and represent potential targets for modulating metabolic disorders or cachexia.

Correlations between growth differentiation factor 15 (GDF-15) serum levels and gene polymorphism with type 2 diabetes mellitus

Purpose

To date, the relationship between Growth Differentiation Factor 15 (GDF-15) gene polymorphism and the risk of type 2 diabetes mellitus (T2DM) has not been clarified. Our study aims to explore the association between serum GDF-15 levels and related gene polymorphism with the risk of T2DM in a Chinese rural Yao population.

Methods

This was a 1:1 case-control study with 179 T2DM patients and 179 age- and sex-matched control participants. Serum GDF-15 levels were measured by enzyme-linked immunosorbent assay, and polymorphisms (rs1059519, rs1059369, rs1804826 and rs1054564) were genotyped by MassArray mass spectrometry.

Results

Serum GDF-15 (sGDF-15) levels were higher in patients with T2DM and glycosylated hemoglobin (HbA1c) ≥ 6.5 % compared to that in controls (p < 0.001). The area under the curve (AUC) corresponding to sGDF-15 levels was 0.626. Serum GDF-15 was positively correlated with fasting plasma glucose (FPG) (rs = 0.150, p < 0.001) and HbA1c (rs = 0.160, p < 0.001). The frequency of GDF-15 gene rs1054564 GC + CC genotype was significantly associated with increased risk of T2DM compared to GG genotype (OR = 1.724, 95CI: 1.046-2.841, p = 0.033). Frequencies of rs1804826 T allele (β additive = 113.318, p = 0.026) and rs1054564 C allele (β additive = 247.282, p = 0.001, β dominant = 286.109, p = 0.001) was significantly correlated with higher sGDF-15. The rs1059519 C allele was negatively correlated with FPG (β recessive = -0.607, p = 0.047) and HbA1c (β recessive = -0.456, p = 0.020).

Conclusion

Serum GDF-15 levels were positively correlated with FPG and HbA1c. The GDF-15 rs1054564 GC + CC genotype was associated with a significantly higher T2DM risk. The rs1059519 C allele was negatively correlated with FPG and HbA1c.

Role and Mechanism of Growth Differentiation Factor 15 in Chronic Kidney Disease

GDF-15 is an essential member of the transforming growth factor-beta superfamily. Its functions mainly involve in tissue injury, inflammation, fibrosis, regulation of appetite and weight, development of tumor, and cardiovascular disease. GDF-15 is involved in various signaling pathways, such as MAPK pathway, PI3K/AKT pathway, STAT3 pathway, RET pathway, and SMAD pathway. In addition, several factors such as p53, ROS, and TNF-α participate the regulation of GDF-15. However, the specific mechanism of these factors regulating GDF-15 is still unclear and more research is needed to explore them. GDF-15 mainly improves the function of kidneys in CKD and plays an important role in the prediction of CKD progression and cardiovascular complications. In addition, the role of GDF-15 in the kidney may be related to the SMAD and MAPK pathways. However, the specific mechanism of these pathways remains unclear. Accordingly, more research on the specific mechanism of GDF-15 affecting kidney disease is needed in the future. In conclusion, GDF-15 may be a therapeutic target for kidney disease.

Growth differentiation factor-15 may be a novel biomarker in pancreatic cancer: A review

Pancreatic cancer is a highly malignant and invasive gastrointestinal tumor that is often diagnosed at an advanced stage with a poor prognosis and high mortality. Currently, carbohydrate antigen199(CA199) is the only biomarker approved by the FDA for the diagnosis of pancreatic cancer, but it has great limitations. Growth differentiation factor-15 (GDF-15) is expected to be a novel biomarker for the diagnosis, efficacy prediction, and prognosis assessment of pancreatic cancer patients. In this paper, we searched the keywords GDF-15, macrophage inhibitory cytokine-1 (MIC-1), CA199, pancreatic cancer, and tumor markers in PubMed and Web of Science, searched related articles, and read and analyzed the retrieved papers. Finally, we systematically described the characteristics, mechanism of action, and clinical value of GDF-15, aiming to provide help for the detection and treatment of pancreatic cancer.

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.

Modelling the Sorafenib-resistant Liver Cancer Microenvironment by Using 3-D Spheroids

Liver cancer is the third leading cause of cancer-related mortality, and hepatocellular carcinoma (HCC) is the most common form of liver cancer, and it usually occurs in the setting of chronic liver disease and cirrhosis. For patients with advanced HCC, systemic treatment is the first choice - however, resistance occurs frequently. Sorafenib was the first tyrosine kinase inhibitor approved for advanced HCC, and resistance to the therapy is a serious concern. When sorafenib therapy fails in a patient, it can be challenging to decide whether they can undergo a second-line therapy, and to determine which therapy they will be able to tolerate. Thus, physiologically relevant in vitro preclinical models are crucial for screening potential therapies, and 3-D tumour spheroids permit studies of tumour pathobiology. In this study, a drug-resistant 3-D tumour spheroid model was developed, based on sorafenib-resistant hepatocellular carcinoma cells, LX2 stellate cells and THP-1 monocytes. Model tumour spheroids that were formed with the sorafenib-resistant cells demonstrated lower diffusion of doxorubicin and exhibited increased resistance to regorafenib. Moreover, in the sorafenib-resistant spheroids, there was increased presence of CD68-positive cells and a reduction in inflammatory marker secretion. The sorafenib-resistant cell line-derived spheroids also showed a higher expression of FGF-19, PDGF-AA and GDF-15, which are known to be involved in malignancies. This multi-cell type spheroid model represents a potentially useful system to test drug candidates in a microenvironment that mimics the drug-resistant tumour microenvironment in HCC.

Circulating GDF-15 in relation to the progression and prognosis of chronic kidney disease: A systematic review and dose-response meta-analysis

BACKGROUND

Patients with chronic kidney disease (CKD) typically exhibit circulating growth differentiation factor-15 (GDF-15) at high levels. This meta-analysis aimed to evaluate the potential value of GDF-15 in predicting CKD progression and prognosis. Furthermore, when sufficient information was provided, the dose-response correlation was studied.

METHODS

Studies were searched in Web of Science, Embase, and PubMed from inception until November 2022. By using random- or fixed-effects models, the pooled effect size was estimated in accordance with heterogeneity in existing research.

RESULTS

This study covered 14 studies from 12 articles with 7813 subjects participating in the research. CKD patients in the top GDF-15 tertile had notably higher risks of CKD progression (HR 2.60, 95% CI 2.06-3.27), all-cause mortality (HR 2.05, 95% CI 1.44-2.92), cardiovascular mortality (HR 2.82, 95% CI 1.85-4.30), and cardiovascular events (HR 2.74, 95% CI 2.21-3.40), as compared to CKD patients in the bottom tertile. In the dose-response study, the risks for CKD progression, all-cause death, cardiovascular death, and cardiovascular events were increased by 31% (HR 1.31, 95% CI 1.06-1.61), 44% (HR 1.44, 95% CI 1.08-1.92), 67% (HR 1.67, 95% CI 1.37-2.03), and 55% (HR 1.55, 95% CI 1.31-1.83), respectively, with per 1 ng/mL increase in GDF-15. The positive linear correlations between GDF-15 and CKD progression and prognosis in a certain GDF-15 concentration range of approximately 0-3 ng/mL were indicated by the dose-response curve.

CONCLUSIONS

Circulating GDF-15 independently predicted CKD progression and worse prognosis; however, the predicted correlations may fall into a specific range of GDF-15 concentrations.

Knockdown of growth differentiation factor-15 inhibited nonsmall cell lung cancer through inactivating PTEN/PI3K/AKT signaling pathway

BACKGROUND

Non-small cell lung cancer (NSCLC) is characterized by high morbidity and mortality in the world. Growth and differentiation factor 15 (GDF15) has been proved to play an important role in regulating tumor progression. However, the influence of GDF15 on NSCLC remains unclear.

OBJECTIVE

We aimed to investigate the regulatory role of GDF15 in NSCLC.

METHODS

The correlation between GDF15 expression and prognosis, stage of NSCLC was examined with bioinformatics method. The cell proliferation was detected with CCK8 and EdU staining. Wound healing, Transwell, flow cytometry assays were used to measure cell migration, invasion, and apoptosis, respectively.

RESULTS

High expression of GDF15 is correlated with worse survival and malignant progression of NSCLC. Knockdown of GDF15 restrained the proliferation, invasion, migration, but accelerated apoptosis of lung cancer cells through regulating PTEN/PI3K/AKT signaling pathway. sh-GDF15 suppressed epithelial mesenchymal transition (EMT) process and promoted the chemotherapy sensitivity of lung cancer cells.

CONCLUSION

GDF15 plays an important role in NSCLC progression. GDF15 mediated PTEN/PI3K/AKT signaling pathway might be the potential therapeutic targets for the prevention and treatment of GDF15.

The effect of acute acid exposure on immunomodulatory protein secretion, cell survival, and cell cycle progression in tumour cell lines

Cancer develops when multiple systems fail to suppress uncontrolled cell proliferation. Breast cancers and oesophageal squamous cell carcinoma (OSCC) are common cancers prone to genetic instability. They typically occur in acidic microenvironments which impacts on cell proliferation, apoptosis, and their influence on surrounding cells to support tumour growth and immune evasion. This study aimed to evaluate the impact of the acidic tumour microenvironment on the production of pro-tumorigenic and immunomodulatory factors in cancer cell lines. Multiple factors that may mediate immune evasion were secreted including IL-6, IL-8, G-CSF, IP-10, GDF-15, Lipocalin-2, sICAM-1, and myoglobin. Others, such as VEGF, FGF, and EGF that are essential for tumour cell survival were also detected. Treatment with moderate acidity did not significantly affect secretion of most proteins, whereas very low pH did. Distinct differences in apoptosis were noted between the cell lines, with WHCO6 being better adapted to survive at moderate acid levels. Conditioned medium from acid-treated cells stimulated increased cell viability and proliferation in WHCO6, but increased cell death in MCF-7. This study highlights the importance of acidic tumour microenvironment in controlling apoptosis, cell proliferation, and immune evasion which may be different at different anatomical sites. Immunomodulatory molecules and growth factors provide therapeutic targets to improve the prognosis of individuals with cancer.

Inclusion Body Myositis and Neoplasia: A Narrative Review

Inclusion body myositis (IBM) is an acquired, late-onset inflammatory myopathy, with both inflammatory and degenerative pathogenesis. Although idiopathic inflammatory myopathies may be associated with malignancies, IBM is generally not considered paraneoplastic. Many studies of malignancy in inflammatory myopathies did not include IBM patients. Indeed, IBM is often diagnosed only after around 5 years from onset, while paraneoplastic myositis is generally defined as the co-occurrence of malignancy and myopathy within 1 to 3 years of each other. Nevertheless, a significant association with large granular lymphocyte leukemia has been recently described in IBM, and there are reports of cancer-associated IBM. We review the pathogenic mechanisms supposed to be involved in IBM and outline the common mechanisms in IBM and malignancy, as well as the therapeutic perspectives. The terminally differentiated, CD8+ highly cytotoxic T cells expressing NK features are central in the pathogenesis of IBM and, paradoxically, play a role in some cancers as well. Interferon gamma plays a central role, mostly during the early stages of the disease. The secondary mitochondrial dysfunction, the autophagy and cell cycle dysregulation, and the crosstalk between metabolic and mitogenic pathways could be shared by IBM and cancer. There are intermingled subcellular mechanisms in IBM and neoplasia, and probably their co-existence is underestimated. The link between IBM and cancers deserves further interest, in order to search for efficient therapies in IBM and to improve muscle function, life quality, and survival in both diseases.

Growth Differentiation Factor-15 as a Biomarker for Sarcopenia in Patients With Chronic Obstructive Pulmonary Disease

Purpose

Sarcopenia is an important factor contributing to comorbidities in patients with chronic obstructive pulmonary disease (COPD) and is an independent risk factor for increased mortality. The diagnostic process for sarcopenia requires specific equipment and specialized training and is difficult procedurally. A previous study found that GDF15 levels are associated with skeletal muscle mass and function in patients with COPD. However, whether circulating GDF15 levels can be used for the prediction of sarcopenia in patients with COPD is unknown.

Methods

This study included 235 patients with stable COPD who were divided into a development set (n = 117) and a validation set (n = 118), and we followed the definition of sarcopenia as defined by the guidelines from the Asian Working Group for Sarcopenia. Serum concentrations of GDF15 were measured using an enzyme-linked immunosorbent assay (ELISA), and construction of a nomogram and decision curve analysis were performed using the R package “rms.”

Results

In this study, serum GDF15 levels were negatively associated with skeletal muscle mass (r = –0.204, p = 0.031), handgrip strength (r = –0.274, p = 0.004), quadriceps strength (r = –0.269, p = 0.029), and the thickness (r = –0.338, p < 0.001) and area (r = –0.335, p < 0.001) of the rectus femoris muscle in patients with COPD. Furthermore, the serum levels of GDF15 in patients with sarcopenia were significantly higher than those in controls. Importantly, serum levels of GDF15 could effectively predict sarcopenia in patients with COPD based on the development set (AUC = 0.827) and validation set (AUC = 0.801). Finally, a nomogram model based on serum GDF15 levels and clinical features showed good predictive ability (AUC > 0.89) in the development and validation sets.

Conclusion

Serum GDF15 levels could be used to accurately and easily evaluate sarcopenia in patients with COPD.

Activated endothelial cells induce a distinct type of astrocytic reactivity

Reactive astrogliosis is a universal response of astrocytes to abnormal events and injuries. Studies have shown that proinflammatory microglia can polarize astrocytes (designated A1 astrocytes) toward a neurotoxic phenotype characterized by increased Complement Component 3 (C3) expression. It is still unclear if inflammatory stimuli from other cell types may also be capable of inducing a subset of C3⁺ neurotoxic astrocytes. Here, we show that a subtype of C3⁺ neurotoxic astrocytes is induced by activated endothelial cells that is distinct from astrocytes activated by microglia. Furthermore, we show that endothelial-induced astrocytes have upregulated expression of A1 astrocytic genes and exhibit a distinctive extracellular matrix remodeling profile. Finally, we demonstrate that endothelial-induced astrocytes are Decorin-positive and are associated with vascular amyloid deposits but not parenchymal amyloid plaques in mouse models and AD/CAA patients. These findings demonstrate the existence of potentially extensive and subtle functional diversity of C3⁺-reactive astrocytes.

Injured endothelial cells are shown to induce an A1 phenotype in astrocytes, characterized by a genetic signature associated with extracellular matrix remodeling factors (e.g. decorin and vascular Aß deposits).

Growth Differentiation Factor-15 in Immunity and Aging

Aging increases susceptibility to and severity of a variety of chronic and infectious diseases. Underlying this is dysfunction of the immune system, including chronic increases in low-grade inflammation (inflammaging) and age-related immunosuppression (immunosenescence). Growth differentiation factor-15 (GDF-15) is a stress-, infection-, and inflammation-induced cytokine which is increased in aging and suppresses immune responses. This mini review briefly covers existing knowledge on the immunoregulatory and anti-inflammatory roles of GDF-15, as well as its potential importance in aging and immune function.

Association of Growth and Differentiation Factor 15 in Rheumatoid Arthritis

Purpose

Rheumatoid arthritis (RA) is an inflammatory rheumatic disease, which has been demonstrated to correlate with mutated genetics. Growth and differentiation factor 15 (GDF-15) is a member of the transforming growth factor-β superfamily and is expressed in different organs, tissues and immune cells. To date, limited studies have evaluated plasma levels of GDF-15 in RA patients, and whether GDF-15 gene polymorphisms correlate with RA risk in the Chinese Han population has not been clarified.

Patients and Methods

This case-control study recruited 910 age- and sex-matched RA patients and healthy controls. Plasma levels of GDF-15 were examined by enzyme linked immunosorbent assay, and polymorphisms (rs1055150, rs1058587, rs3787023, and rs4808793) were genotyped by KASP method.

Results

RA patients had higher levels of GDF-15 as compared to that in healthy controls. Patients with positive CRP also showed higher levels of GDF-15 when compared to that in patients with negative CRP. Levels of GDF-15 correlated with disease activity score. Frequencies of GG, GC, GG+GC genotypes and G allele in GDF-15 gene rs1058587 were significantly elevated in RA patients compared to controls. Frequencies of CC genotype and C allele in GDF-15 gene rs3787023 were higher in RA patients compared to controls. Other polymorphisms did not correlate with RA susceptibility. Moreover, the four polymorphisms were not correlated with levels of GDF-15.

Conclusion

Plasma levels of GDF-15 were elevated in RA patients and GDF-15 gene polymorphisms were related to RA risk in the Chinese Han population.