Meteorin-like protein is associated with a higher risk profile and predicts a worse outcome in patients with STEMI

Higher serum Metrnl levels are associated with increased vascular calcification in hemodialysis patients

BACKGROUND

Meteorin-like (Metrnl) is a newly identified secreted protein that plays important roles in metabolic and inflammation-related diseases. Our study aimed to evaluate serum Metrnl levels and establish their relationship with vascular calcification (VC) in hemodialysis (HD) patients.

METHODS

In total, 313 HD patients and 41 healthy individuals, as controls, were included. Serum levels of Metrnl and other clinical and laboratory parameters were compared. VC was evaluated based on the abdominal aortic calcification (AAC) scores. HD patients were divided into a high-AAC score group (AAC score ≥ 4) and a low-AAC score group (AAC score < 4).

RESULTS

HD patients had higher serum Metrnl levels than the controls (0.52 ± 0.26 ng/ml vs. 0.24 ± 0.11 ng/ml, p < 0.001). Serum Metrnl concentrations were significantly higher in HD patients in the high-AAC score group than in those in the low-AAC score group (0.55 ± 0.27 vs. 0.49 ± 0.24 ng/ml, p = 0.041). Multivariate logistic regression revealed that serum Metrnl, age, diabetes mellitus, serum total carbon dioxide (tCO2) and serum intact parathyroid hormone (iPTH) were significant independent determinants of high AAC scores.

CONCLUSION

The results herein provide the first clinical evidence of the association between serum Metrnl and VC in HD patients. Higher Metrnl levels, older age, diabetes mellitus, and higher serum tCO2 and iPTH levels are independent determining factors for high AAC scores in HD patients.

Meteorin-like protein plasma levels are associated with worse outcomes in de novo heart failure

BACKGROUND AND AIMS

Meteorin-like protein (Metrnl) has been recently suggested as a new adipokine with protective cardiovascular effects. Its circulating levels in patients seem to be associated with heart failure (HF), although with contradictory results. Our aim was to ascertain whether this adipokine could estimate the prognosis of HF in de novo HF (DNHF) patients.

METHODS

Metrnl plasma levels of 400 patients hospitalized with DNHF (55% of patients with HF with reduced ejection fraction, 17.3% HF with mid-range ejection fraction, 27.8% HF with preserved ejection fraction) were measured by enzyme-linked immunosorbent assay. We performed both sex-pooled and sex-specific analyses. A 12-month follow-up was conducted, during which clinical outcomes such as all-cause mortality, cardiovascular death and re-hospitalization due to HF were collected.

RESULTS

After a 12-month follow up, higher plasma Metrnl levels were associated with an increased risk for all-cause death and cardiovascular death after adjusting by sex, age, LVEF, hypertension, diabetes, ischemic aetiology, chronic renal failure, NT-proBNP and troponin (hazard ratio [HR] = 1.003, 95% confidence interval [CI] = 1.000-1.005; p-value<.05 and HR = 1.004, 95% CI = 1.001-1.007, p-value<.05, respectively). In line with this, DNHF patients with increased levels of circulating Metrnl had a higher number of occurrences of cardiovascular events. Regarding Metrnl associations with parameters implicated in the development and progression of HF, we found that Metrnl circulating levels were positively correlated with age (r = .322, p-value<.0001), NT-proBNP (r = .281, p-value<.0001) and with the renal dysfunction markers urea (r = .322, p-value<.0001) and creatinine (r = .353, p-value<.0001) and higher in women than men (473.7 [385.9-594.0] pg/mL vs. 428.7 [349.1-561.3] pg/mL, p-value<.006). Finally, concerning the subtype of HF, Metrnl plasma levels were higher in HF with preserved ejection fraction.

CONCLUSION

Patients with higher Metrnl levels have a worse prognosis in DNHF. Our results reinforce the association of Metrnl plasma levels with HF progression and outcomes.

Metrnl as a secreted protein: Discovery and cardiovascular research

Secreted proteins have gained more and more attentions, since they can become therapeutic targets, drugs and biomarkers for prevention, diagnosis and treatment of disease and aging. In 2014, Metrnl (also named Meteorin-like, Cometin, Subfatin, Interleukin-39, Interleukin-41, Meteorin-β, and Metrn-β/Metrnβ), as a novel secreted protein released from a certain tissue, was reported by us and others. During the past decade, the number of articles on Metrnl has continued to increase. Different sources of Metrnl have been described with different functions, including Metrnl as an adipokine for insulin sensitization, a cardiokine against cardiac hypertrophy and dysfunction, an endothelium-derived factor against endothelial dysfunction and atherosclerosis, etc. Especially, we show that endothelial Metrnl is a major source for circulating Metrnl levels. Meanwhile, lots of clinical studies have investigated the relationship between blood Metrnl levels and metabolic, inflammatory and cardiovascular diseases. Metrnl appears a protective factor and a promising therapeutic target and/or drug against these diseases, given the relatively consistent conclusion from the preclinical studies. In addition to graphically demonstrating the role of Metrnl in various organs and diseases, this review will mainly describe the discovery of Metrnl, summarize the role of Metrnl in cardiovascular system that is a recently major progress in Metrnl research, and highlight several perspectives for future basic and translational research. Also, we suggest using one name Metrnl instead of other multiple names for the same protein.

Metrnl: a promising biomarker and therapeutic target for cardiovascular and metabolic diseases

Modern human society is burdened with the pandemic of cardiovascular and metabolic diseases. Metrnl is a widely distributed secreted protein in the body, involved in regulating glucose and lipid metabolism and maintaining cardiovascular system homeostasis. In this review, we present the predictive and therapeutic roles of Metrnl in various cardiovascular and metabolic diseases, including atherosclerosis, ischemic heart disease, cardiac remodeling, heart failure, hypertension, chemotherapy-induced myocardial injury, diabetes mellitus, and obesity.

Meteorin-like protein elevation post-exercise improved vascular inflammation among coronary artery disease patients by downregulating NLRP3 inflammasome activity

BACKGROUND

Coronary artery disease (CAD) has become the most common cause of death worldwide. However, the negative effects of CAD are able to be alleviated via exercises, possibly via increased production of meteorin-like protein (Metrnl). In this study, we aim to evaluate the connection between Metrnl production during exercise with lowered CAD risk and severity.

METHODS

Two age and gender-matched groups of 60 human patients, one with CAD, and one without were randomly recruited. The CAD group were subjected to continuous training exercises. Mice were exercised by using a treadmill, establishing an animal exercise model. ELISA was used to measure plasma Metrnl and inflammatory factors. To determine the impact of Metrnl on glucose metabolism, oxygen consumption and extracellular acid rates were taken for untreated, palmitic acid (PA)-treated, and PA+Metrnl co-treated human umbilical vein endothelial cells. Western blot was used to measure expression levels for the NLR family pyrin domain containing 3 inflammasome.

RESULTS

CAD patients had lower Metrnl levels compared to non-CAD controls. Furthermore, higher Metrnl levels post-exercise were inversely associated with LDL, inflammatory cytokines, and CAD severity, as well as being positively associated with HDL. Metrnl was able to counteract against PA-induced HUVEC glucose metabolic dysfunction via reducing ROS production, which in turn lowered NLRP3 inflammasome expression, thereby serving as the basis behind the inverse correlation between Metrnl and inflammatory cytokines.

CONCLUSIONS

Exercise was able to increase Metrnl production from skeletal muscle among CAD patients, and subsequently improve patient atherosclerosis via counteracting against endothelial metabolic dysfunction and pro-inflammatory activities.