Serum β-klotho is a potential biomarker for diagnosing alcoholic liver disease and differentiating from nonalcoholic fatty liver disease

Abstract

Background: Alcoholic liver disease (ALD), with the control of infectious liver disease and the improvement in living standards, is emerging as a significant liver disease posing a threat to public health. Besides, ALD often overlaps or coexists with nonalcoholic fatty liver disease (NAFLD), however, due to the lack of specific non-invasive biomarkers and the fact that drinkers' self-reported alcohol consumption is often concealed, the identification of ALD and NAFLD is sometimes not easy. This study aims to explore a new specific serum biomarker to more easily diagnose ALD and differentiate it from NAFLD.

Subjects and methods: A total of 204 serum samples were collected, including 70 from ALD patients, 68 from NAFLD patients and 66 from healthy controls (HC). Serum β-klotho (sKLB) levels were measured using the enzyme-linked immunosorbent assay (ELISA). The diagnostic performance of potential biomarkers was evaluated using the area under the receive operating characteristic curve (AUROC).

Results: The levels of sKLB were significantly elevated (1,332.12 (410.40, 2,687.00) pg/mL, p < 0.001) in ALD patients and significantly reduced in NAFLD patients (47.82 (32.76, 77.11) pg/mL, p = 0.018) compared to the healthy controls. The AUROC for sKLB in diagnosing ALD is 0.927, which was higher than that for the aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratio (0.672) and γ-glutamyl transpeptidase (GGT) (0.891). The combined AUROC for sKLB + AST/ALT, sKLB + GGT, and AST/ALT ratio + GGT in diagnosing ALD were 0.924, 0.967 and 0.917, respectively.

Conclusion: sKLB is a potential biomarker for diagnosing ALD, and may aid in differentiating between ALD and NAFLD, when combined with GGT, sKLB offers enhanced diagnostic sensitivity and specificity for ALD.

Keywords: Alcoholic liver disease; Biomarker; Nonalcoholic fatty liver disease; Serum β-klotho.

Figure 1. The sKLB, GGT level and AST/ALT ratio expression in the difference groups.

(A) sKLB level expression in HC, NAFLD, and ALD groups, N = 66, 68, 70; (B) AST/ALT ratio expression in HC and ALD groups, N = 66, 70; (C) GGT level expression in HC and ALD groups, N = 66, 70; (D) sKLB level expression in AFLD, AC and ALF groups, N = 25, 25, 20. ALFD, alcoholic fatty liver disease; AC, alcoholic cirrhosis; ALF, alcoholic liver failure. Data are depicted as box-and-whisker plots, illustrating the distribution of values within each group. The central horizontal line within each box signifies the median. The upper and lower boundaries of the box denote the 75th and 25th percentiles (quartiles), respectively; the whiskers extend to the 10th and 90th percentiles and the dots represent the outliers. The median represents the middle value of the data, while the interquartile range represents the middle 50% of the data. *p < 0.05; **p < 0.01; ****p < 0.0001; ns, not significant.

Figure 2. Serum markers associated with ALD were used to construct a receiver operating characteristic (ROC) curve.

The ROC curve demonstrates the diagnostic performance of serum markers (sKLB, AST/ALT, and GGT) in ALD. (A) ALD of sKLB: AUROC (the areas under the ROC curve) = 0.927 (95% CI [0.886–0.968]), sensitivity = 80.0%, specificity = 87.9%; (B) ALD of AST/ALT ratio: AUROC = 0.658 (95% CI [0.577–0.767]), sensitivity = 61.4%, specificity = 78.8%; (C) ALD of GGT: AUROC = 0.867 (95% CI [0.838–0.946]), sensitivity = 75.7%, specificity = 90.9%.

Figure 3. Receiver operating characteristic curve for s KLB + AST/ALT, sKLB + GGT and AST/ALT + GGT in the ALD group.

(A) ALD of sKLB + AST/ALT ratio: AUROC = 0. 924 (95% CI [0.881–0.966]), sensitivity = 81.4%, specificity = 89.4%; (B) ALD of sKLB + GGT: AUROC = 0.967 (95% CI [0.943–0.992]), sensitivity = 90.0%, specificity = 92.4%; (C) ALD of AST/ALT ratio + GGT: AUROC = 0.917 (95% CI [0.870–0.964]), sensitivity = 84.3%, specificity = 87.9%.