A meta-analysis of the relationship between serums metrnl-like protein/subfatin and risk of type 2 diabetes mellitus and coronary artery disease

Meteorin-like/Metrnl, a novel secreted protein implicated in inflammation, immunology, and metabolism: A comprehensive review of preclinical and clinical studies

Meteorin-like, also known as Metrnl, Meteorin-β, Subfatin, and Cometin, is a novel secreted protein exerting pleiotropic effects on inflammation, immunology, and metabolism. Earlier research on this hormone focused on regulating energy expenditure and glucose homeostasis. Consequently, several studies attempted to characterize the molecule mechanism of Metrnl in glucose metabolism and obesity-related disorders but reported contradictory clinical results. Recent studies gradually noticed its multiple protective functions in inflammatory immune regulations and cardiometabolic diseases, such as inducing macrophage activation, angiogenesis, tissue remodeling, bone formation, and preventing dyslipidemias. A comprehensive understanding of this novel protein is essential to identify its significance as a potential therapeutic drug or a biomarker of certain diseases. In this review, we present the current knowledge on the physiology of Metrnl and its roles in inflammation, immunology, and metabolism, including animal/cell interventional preclinical studies and human clinical studies. We also describe controversies regarding the data of circulation Metrnl in different disease states to determine its clinical application better.

Meteorin-like protein (Metrnl): A metabolic syndrome biomarker and an exercise mediator

Metrnl is a secreted protein able to activate different intracellular signaling pathways in adipocytes, macrophages, myocytes and cardiomyocytes with physiological effects of the browning of white adipose tissue (BWT), insulin sensitivity, inflammation inhibition, skeletal muscle regeneration and heart protection. Shown to be regulated by obesity, diabetes, caloric restriction, weight loss and heart diseases, Metrnl is definitely involved in metabolic turbulences, and may play roles in metabolic syndrome (MetS). However, due to the conflicting data yielded, Metrnl is still far from clinical application as a diagnostic and/or a therapeutic agent or even a therapeutic target in MetS-related diseases such as type 2 diabetes (T2D) and obesity. Nevertheless, blood Metrnl levels as well as Metrnl as a cardiokine have been reported to play cardioprotective roles against heart diseases. Considering the established metabolic and anti-inflammatory hallmarks, exercise-induced Metrnl (as a myokine) is regarded as an exercise mediator in improving obesity-induced complications such as insulin resistance, T2D and inflammation. Besides, due to its healing role in muscle damage, Metrnl is also a potential therapeutic candidate to enhance regeneration with ageing or other inflammatory myopathies like Duchenne muscular dystrophy (DMD). Therefore, there are still many exercise-related questions unanswered on Metrnl, such as Metrnl-mediated fat browning in humans, exercise effects on heart Metrnl production and secretion and the effects of other exercise-induced skeletal muscle stressors like hypoxia and oxidative in Metrnl production other than exercise-induced muscle damage.

Subfatin concentration decreases in acute coronary syndrome

Introduction

We investigated the association of serum subfatin concentration and acute myocardial infarction (AMI) in patients with ST-elevation myocardial infarction (STEMI) and non-STEMI (NSTEMI).

Materials and methods

In this study, patients who presented with chest pain (STEMI, NSTEMI, or non-cardiac chest pain) were included, i.e. 49 patients with non-cardiac chest pain (control) and 66 patients hospitalised with AMI. In the AMI group, 35 patients had NSTEMI and 31 had STEMI. Serum subfatin concentrations were determined via enzyme-linked immunosorbent assay (ELISA). Descriptive data on the patients and their comorbidities were recorded, and subfatin concentrations were analysed.

Results

Subfatin concentrations were significantly different in the control, STEMI and NSTEMI groups (P = 0.002). In addition, subfatin concentrations were significantly lower in patients in the NSTEMI group than those in the control group (P < 0.001), but there was no significant difference between STEMI and the control group (P = 0.143). The receiver operating characteristic (ROC) analysis performed for differentiating the AMI and control groups found that subfatin had 64% sensitivity and 69% specificity, whereas troponin had 59% sensitivity and 95% specificity. In patients with AMI, the ROC analysis for differentiating NSTEMI from STEMI found that subfatin had 94% sensitivity and 41% specificity, while troponin had 65% sensitivity and 88% specificity.

Conclusions

Subfatin concentrations were lower in patients without STEMI than in patients with STEMI. Subfatin concentration is associated with NSTEMI.

Serum Metrnl levels are decreased in subjects with overweight or obesity and are independently associated with adverse lipid profile

BACKGROUND

Meteorin-like (Metrnl), a novel adipokine, is highly expressed in adipose tissue and has a beneficial effect on energy metabolism. However, data on circulating Metrnl levels in obesity are scarce and inconsistent. This study aimed to evaluate the serum levels of Metrnl in adults with obesity and its association with glucose and lipid metabolism.

METHODS

182 subjects were included in the cross-sectional study. The participants were divided into three groups according to BMI: normal (n = 95), overweight (n = 46), and obesity (n = 41). Serum Metrnl concentrations were measured by enzyme-linked immunosorbent assay.

RESULTS

Serum Metrnl levels in overweight or obese subjects were significantly lower than in the normal group. Circulating Metrnl levels were negatively correlated with TG, TC, LDL-C, and sdLDL and positively correlated with HDL-C before and after adjusting for age, sex, BMI, diabetes, HOMA-IR, and eGFR (all P < 0.05). Furthermore, logistic regression analysis indicated that compared with the highest tertile, the lowest tertile of Metrnl levels were significantly associated with the presence of hyper-TG, hyper-TC, and Hyper-LDL after full adjustment (all P for trend < 0.05).

CONCLUSIONS

Serum Metrnl levels were reduced in individuals with overweight or obesity and were independently associated with adverse lipid profile, suggesting that modifying circulating Metrnl levels may serve as a potential therapeutic target for atherogenic dyslipidemia.

New Discovered Adipokines Associated with the Pathogenesis of Obesity and Type 2 Diabetes

Obesity is defined as abnormal or excessive accumulation of adipose tissue, closely associated with the increased risk of various comorbidities, especially type 2 diabetes mellitus (T2DM). Adipose tissue is a complex structure responsible for not only fat storage but also releasing adipokines which may play roles in the pathogenesis and could be developed into biomarkers for diagnosis, treatment and prognosis of obesity-related metabolic diseases. This review aims to summarize several adipokines discovered recently that have promising functions in obesity and T2DM. Among them, the levels of FSTL1, WISP1 and Asprosin in subjects with obesity or diabetes are commonly higher than in normal controls, suggesting that they may be pathogenic. Inversely, SFRP5, Metrnl, NRG4 and FAM19A5 may serve as the protective factors.