Changes in Isthmin-1, Irisin, and the AGE–RAGE Axis Following LSG: A Prospective Single-Center Cohort Study

This prospective single-center cohort study evaluated changes in serum levels of novel adipokines and myokines, including isthmin-1 and irisin, as well as the advanced glycation end product (AGE)–soluble receptor for AGE (sRAGE) axis and monomeric C-reactive protein (mCRP) in patients with obesity before and 5 months after laparoscopic sleeve gastrectomy (LSG). The study included 38 patients with obesity (26 females and 12 males) with a median age of 42 years who underwent LSG. Laboratory parameters were assessed using commercially available immunoenzymatic assays. We observed a significant decrease in isthmin-1 concentration at the postoperative time point (Me = 2.10 ng/mL vs. Me = 1.93 ng/mL, p = 0.009). Moreover, a significant increase in irisin levels (Me = 7.33 µg/mL vs. Me = 10.64 µg/mL, p = 0.002) and AGEs (Me = 589.50 ng/mL vs. Me = 698.60 ng/mL, p = 0.015) was observed after LSG. A significant increase in AGE levels was also noted after normalization to total protein (Me = 8.34 ng/mg protein vs. Me = 10.37 ng/mg protein, p = 0.027). sRAGE levels were similar at both time points. Five months after LSG, mCRP levels were significantly lower (Me = 1.99 ng/mL vs. Me = 1.55 ng/mL, p = 0.020). Exploratory correlation analyses identified potential associations between AGEs and isthmin-1 (R = 0.37) and between sRAGE and irisin (R = −0.31) preoperatively. Five months after LSG, potential associations were observed between AGEs and irisin (R = 0.38) and between sRAGE and mCRP (R = −0.37). Our findings indicate a decrease in circulating isthmin-1 and mCRP, together with an increase in irisin and AGE concentrations following LSG, suggesting changes in selected metabolic and tissue-related biomarkers after surgery. Further studies are needed to determine the mechanisms underlying these changes and to clarify their potential clinical significance.