Irisin and Cardiometabolic Disorders in Obesity: A Systematic Review

Background. Overweight and obesity are global health issues, impacting a significant portion of young adults. Obesity is a complex condition influenced by genetics and environmental factors, leading to increased susceptibility to cardiovascular diseases (CVDs), hypertension, dyslipidemia, and insulin resistance. Irisin, a protein derived from the cleavage of fibronectin type III domain-containing protein 5, may have relationship with these cardiometabolic diseases. Objective. This systematic review aims to examine the relationship between serum irisin levels and obesity, particularly in individuals predisposed to cardiovascular risk factors. Methods. A thorough literature search was conducted in multiple databases, including "Science Direct," "Scopus," "PubMed," and "Lilacs," from July 2020. Inclusion criteria encompassed subjects with metabolic disorders (with or without obesity, BMI >= 30 kg/m2), clinical trials, and observational studies published between 2010 and June 2020. Exclusion criteria were animal studies, meta-analyses, systematic reviews, studies evaluating only healthy subjects, and those investigating disorders beyond cardiometabolic diseases. Results. Out of 151 identified articles, 30 met the inclusion criteria. These studies, published between 2013 and 2020, assessed adults (>= 21 years) and included 26 observational studies and 4 clinical trials (n = 7585 subjects). All studies examined irisin's role in obesity and CVDs, often including associated diseases such as type 2 diabetes and hypertension. Despite varying sample sizes, the samples within the articles were homogeneous. Observational studies exhibited a low risk of bias in at least 60% of the evaluated domains. Clinical trials demonstrated a low risk of bias in at least 50% of the domains. Limitations. Although the systematic review provides valuable insights, it is limited by the available literature and the varying methodologies used across studies. Conclusion. The review suggests that irisin plays a significant role as both a preventive measure and a biomarker for comorbidities linked to obesity and cardiometabolic disorders. Future research should focus on standardized irisin measurement methods and diverse populations to further elucidate its mechanisms of action.