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

Meteorin-β: A Novel Biomarker and Therapeutic Target on Its Way to the Regulation of Human Diseases

The novel secreted protein Meteorin-β (Metrnβ) is a homologous protein of the neurotrophic regulator Meteorin, which is widely expressed in the skin, mucous membranes, and white adipose tissue upon stimulation by a variety of inflammatory mediators, including cytokines and chemokines, while, at the same time Metrnβ may also regulate the expression of these cytokines and chemokines. As a small secreted protein with low tissue specificity, Metrnβ plays vital roles in energy metabolism, insulin sensitivity regulation, neurodevelopment, white fat browning, and inflammatory response. Specifically, Metrnβ may act as an adipokine, myokine, neurotrophic factor, and cytokine, thereby being involved in the pathological and physiological processes of various human diseases, including metabolic, autoimmune and infectious/allergic diseases, and certain types of tumors. This review aims to systematically introduce the current research progress on Metrnβ, including its expression and distribution profiles, biological functions, and immunomodulatory roles in the process of human diseases. Additionally, we also discuss its potential as a biomarker, as well as a therapeutic/preventive agent for human diseases.

Meteorin-like protein (Metrnl): a key exerkine in exercise-mediated cardiovascular health

CONTEXT

Cardiovascular diseases (CVDs) remain a leading global cause of mortality, necessitating non‑pharmacological interventions such as exercise. Meteorin‑like protein (Metrnl), an exercise‑induced myokine and adipokine, has emerged as a critical mediator of exercise‑mediated cardiovascular benefits, though its specific mechanisms and clinical implications remain underexplored.

OBJECTIVE

This review synthesizes current evidence on Metrnl's role as a key exerkine in cardiovascular health, focusing on its exercise‑induced regulatory mechanisms, tissue‑specific effects, and therapeutic potential for CVD management.

METHODS

A comprehensive analysis of preclinical and clinical studies was conducted, encompassing molecular, metabolic, and anti‑inflammatory pathways linked to Metrnl. Literature from PubMed, Scopus, and Web of Science was systematically reviewed to evaluate Metrnl's role in exercise‑mediated cardiovascular adaptations.

RESULTS

Exercise‑induced Metrnl enhances endothelial function, vascular remodeling, and metabolic regulation via AMPK, PPARγ, and KIT receptor signaling. It promotes glucose/lipid metabolism, angiogenesis, and anti‑inflammatory responses, reducing atherosclerotic risks and improving cardiac repair post‑infarction. Clinically, Metrnl levels correlate with CVD severity, acting as a biomarker for risk stratification. Acute exercise elevates Metrnl, while chronic training effects vary by modality and population. Paradoxically, elevated plasma Metrnl in acute cardiac events predicts adverse outcomes, whereas reduced levels in chronic conditions (e.g., diabetes, heart failure) reflect metabolic dysregulation.

DISCUSSION

Metrnl bridges exercise benefits to cardiovascular health through inter‑organ crosstalk, yet discrepancies exist in its chronic exercise‑mediated regulation. Its dual role as a protective mediator and stress‑responsive biomarker underscores context‑dependent interpretations. Unresolved questions include receptor specificity, tissue autonomy, and therapeutic delivery strategies.

CONCLUSION

Metrnl is a pivotal exerkine with promising diagnostic and therapeutic potential for CVDs. Translating its exercise‑mediated benefits into clinical applications requires further human trials to validate mechanisms and optimize interventions. Harnessing Metrnl could revolutionize strategies for CVD prevention and rehabilitation, leveraging exercise's molecular advantages.

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.

Unraveling the Mystery of Insulin Resistance: From Principle Mechanistic Insights and Consequences to Therapeutic Interventions

Insulin resistance (IR) is a significant factor in the development and progression of metabolic-related diseases like dyslipidemia, T2DM, hypertension, nonalcoholic fatty liver disease, cardiovascular and cerebrovascular disorders, and cancer. The pathogenesis of IR depends on multiple factors, including age, genetic predisposition, obesity, oxidative stress, among others. Abnormalities in the insulin-signaling cascade lead to IR in the host, including insulin receptor abnormalities, internal environment disturbances, and metabolic alterations in the muscle, liver, and cellular organelles. The complex and multifaceted characteristics of insulin signaling and insulin resistance envisage their thorough and comprehensive understanding at the cellular and molecular level. Therapeutic strategies for IR include exercise, dietary interventions, and pharmacotherapy. However, there are still gaps to be addressed, and more precise biomarkers for associated chronic diseases and lifestyle interventions are needed. Understanding these pathways is essential for developing effective treatments for IR, reducing healthcare costs, and improving quality of patient life.

Skeletal muscle growth to combat diabetes and obesity: the potential role of muscle-secreted factors

As the prevalence of obesity and metabolic disease continues to climb, the need for effective therapeutic interventions remains high. The growth of skeletal muscle (SkM) greatly influences systemic metabolism across the whole body, making this tissue an important therapeutic target to combat the rise of metabolic dysfunction. Transgenic rodent models of targeted SkM growth exhibit profound improvements in various remote tissues, including adipose tissue and the liver. It is currently unclear how selective stimulation of SkM growth alters the metabolism of distant tissues; however, evidence suggests that muscle-secreted factors may be involved. Here, we aim to provide basic biomedical researchers with a summary of the current knowledge regarding various muscle-secreted factors regulated by anabolic pathways and proteins in SkM, as well as their systemic metabolic effects, to implicate them in the whole-body metabolic effects of SkM growth. In this review, we also identify several knowledge gaps in this field, future directions of investigation, and implications for therapeutic interventions such as resistance exercise and pharmacology.

Metrnl and Cardiomyopathies: From Molecular Mechanisms to Therapeutic Insights

Cardiomyopathies, a diverse group of diseases affecting the heart muscle, continue to pose significant clinical challenges due to their complex aetiologies and limited treatment options targeting underlying genetic and molecular dysregulations. Emerging evidence indicates that Metrnl, a myokine, adipokine and cardiokine, plays a significant role in the pathogenesis of various cardiomyopathies. Therefore, the objective of this review is to examine the role and mechanism of Metrnl in various cardiomyopathies, with the expectation of providing new insights for the treatment of these diseases.