Adiponectin, Leptin, and IGF-1 Are Useful Diagnostic and Stratification Biomarkers of NAFLD

Figure 1. Leptin serum levels allow to distinguish NAFLD. (A) In the discovery cohort, leptin levels were significantly higher in NAFL and NASH patients compared with non-obese, healthy-liver controls, presenting an AUROC value of 0.88 when distinguishing controls (n = 13) from NAFLD patients (n = 36), with very high general accuracy and NPV. (B) In the validation cohort, the leptin levels did not show differences among healthy controls, non-obese or obese, and confirmed increased levels in NAFL and NASH. Leptin presented good performance assay results when distinguishing healthy controls (n = 31) from NAFLD (n = 194), with an AUROC value of 0.83 and overall accuracy of 0.60 when applied the cutoff value of >9.33 ng/ml leptin for NAFLD diagnosis established in the discovery cohort. (C) Main correlations found between leptin and other parameters in the validation cohort: BMI values (n = 199), hepatic TG evaluated by Folch method (n = 140; mg TG/g liver tissue), glucose (n = 198), HDL (n = 167), platelets (n = 172), and total bilirubin (n = 171). (D) Leptin levels increased with steatosis severity in the validation cohort. The x-axis represents the histological grade of steatosis, ranging…

Figure 2. Serum lipidomic signatures associated with higher circulating levels of leptin (dark gray) and adiponectin (light gray). Data presented as log2 of the lipid level fold change between patients with hormone levels higher than the median vs. lower than the median. Leptin median level = 39.61 ng/ml; higher, n = 99; lower, n = 99. Adiponectin median level = 4.84 μg/ml; higher, n = 95; lower, n = 99. Cer, ceramide; ChoE, cholesteryl ester; DG, diglyceride; FA, fatty acid; LPC, lysophosphatidylcholines; LPE, lysophosphatidylethanolamines; LPI, lysophosphatidylinositols; MUFA, monounsaturated FA; PC, phosphatidylcholines; PE, phosphatidylethanolamines; PI, phosphatidylinositols; PUFA, polyunsaturated FA; SFA, saturated FA; SM, sphingomyelins; ST, steroids; TG, triglycerides; 16:0, palmitic acid; 18:3, linolenic acid; 20:4, arachidonic acid; 22:6n-3, docosahexaenoic acid (DHA). *p < 0.05; **p < 0.01; ***p < 0.001.

Figure 3. Adiponectin serum levels differentiate NAFL and NASH, but PNPLA3 genotype may be a confounding factor. (A) In the discovery cohort, the adiponectin serum levels were significantly lower in NASH when compared to NAFL, presenting an AUROC value of 0.87 and very high sensitivity and NPV (non-obese control, n = 8; NAFL, n = 19; NASH, n = 12). (B) In the validation cohort, adiponectin distinguishes NAFL from NASH only within PNPLA3 CC allele carriers, with an AUROC value superior to 0.6 obese controls, n = 7; NAFL, n = 59, NASH, n = 47). (C) In the validation cohort, NAFLD patients with PNPLA3 GG genotype also showed increased levels of adiponectin. The x-axis represents the three possible genotypes for rs738409 polymorphism: CC allele, n = 117; CG allele, n = 55; GG allele, n = 16). (D) Correlations between adiponectin serum levels and several parameters: AST and ALT serum levels (both n = 199), HDL and LDL serum levels (both n = 167), total cholesterol levels (n = 168), and triglyceride serum levels (n = 168). (E) The adiponectin levels decreased with higher grades of steatosis. The x-axis represents the histological grade of steatosis, ranging from 0 to 3. There was a significant…

Figure 4. IGF-1 serum levels correlated with liver fibrosis score. (A) In the discovery cohort, the IGF-1 serum levels were slightly lower in NASH patients compared to NAFL and non-obese contros. (B) No significant differences in IGF-1 levels were found among controls and patients with NAFLD in the validation cohort. (C) In the validation cohort, NAFLD patients with advanced fibrosis presented significantly lower levels of IGF-1. The x-axis represents fibrosis score dichotomy: none to moderate fibrosis (F0-2; n = 184) and advanced fibrosis to cirrhosis (F3-4; n = 19). IGF-1 alone presents an AUROC value of 0.67 when distinguishing F0-2 vs. F3-4. (D) Serum lipidomic signature associated with higher IGF-1 circulating levels. Data presented as log2 of the fold change between higher vs. lower than the median IGF-1 level (103.65 ng/ml). Higher, n = 97; lower, n = 97. IGF-1 levels depicted as mean ± SEM. Cer, ceramide; ChoE, cholesteryl ester; CI, confidence interval; DAPC, diacylglycerophosphocholine; DG, diglyceride; FA, fatty acid; IGF-1, insulin-like growth factor 1; LPC, lysophosphatidylcholines; LPE, lysophosphatidylethanolamines; LPI, lysophosphatidylinositols; MAPE,…