Associations Between Klotho/FGF-Related Protein Expression in Peripheral Blood Mononuclear Cells, Inflammation, and Muscle Function in Middle-Aged Adults with Obesity: A Pilot Study

This pilot study aimed to investigate the role of the Klotho/FGF (fibroblast growth factor) system in biological features associated with premature aging, particularly inflammation and muscle dysfunction, focusing on its association with inflammatory markers, body composition, and muscle function in middle-aged adults. A total of 45 participants aged 50-60 years were enrolled, including 30 patients with obesity (22F/8M) and 15 healthy controls (11F/4M). Comprehensive assessments were conducted, including body composition analysis and muscle function tests. Evaluations of protein expression of Klotho, β-Klotho, FGF19, FGF21, FGF23, TFN-α and IL-10 were assessed in peripheral blood mononuclear cells (PBMCs). A Principal Component Analysis (PCA) was carried out to explore the relationships among variables. Significant differences were observed between the obese and control groups, with obese individuals exhibiting lower levels of Klotho and higher levels of TFN-α. The PCA revealed that higher Klotho levels were positively associated with better muscle function and lower inflammatory markers. These associations suggest that Klotho-related alterations may reflect biological processes linked to inflammation and muscle dysfunction in obesity. These findings suggest that alterations in the Klotho/FGF system may reflect biological pathways commonly associated with aging-related phenotypes in obesity, rather than direct measures of chronological aging. Given the exploratory design and limited sample size, these findings should be interpreted as hypothesis-generating rather than evidence of causal mechanisms.