Individuals with Primary Sclerosing Cholangitis Have Elevated Levels of Biomarkers for Apoptosis but Not Necrosis.

BACKGROUND AND AIM: Hepatocyte apoptosis or necrosis from accumulation of bile salts may play an important role in the disease progression of primary sclerosing cholangitis (PSC). The aim of the current study was to measure serum markers of hepatocyte apoptosis (cytokeratin-18 fragments--K18) and necrosis (high-mobility group protein B1--HMGB1) in adults with PSC and examine the relationship with disease severity. METHODS: We measured serum levels of K18 and HMGB1 in well-phenotyped PSC (N = 37) and 39 control subjects (N = 39). Severity of PSC was assessed biochemically, histologically, and PSC Mayo risk score. Quantification of hepatocyte apoptosis was performed using TUNEL assay. RESULTS: The mean age of the study cohort was 49.7 ± 13.3 years and comprised of 67% men and 93% Caucasian. Serum K18 levels were significantly higher in the PSC patients compared to control (217.4 ± 78.1 vs. 157.0 ± 58.2 U/L, p = 0.001). However, HMGB1 levels were not different between the two groups (5.38 ± 2.99 vs. 6.28 ± 2.85 ng/mL, p = 0.15). Within the PSC group, K18 levels significantly correlated with AST (r = 0.5, p = 0.002), alkaline phosphatase (r = 0.5, p = 0.001), total bilirubin (r = 0.61, p ≤ 0.001), and albumin (r = -0.4, p = 0.02). Serum K18 levels also correlated with the level of apoptosis present on the liver biopsy (r = 0.8, p ≤ 0.001) and Mayo risk score (r = 0.4, p = 0.015). CONCLUSION: Serum K18 but not HMGB1 levels were increased in PSC and associated with severity of underlying liver disease and the degree of hepatocyte apoptosis.

Relationship between changes in serum levels of keratin 18 and changes in liver histology in children and adults with nonalcoholic fatty liver disease.

BACKGROUND & AIMS: Cross-sectional studies have associated serum levels of the keratin 18 (K18) fragment with histologic features of liver in individuals with nonalcoholic fatty liver disease (NAFLD). We investigated the relationship between changes in serum levels of K18 and changes in liver histology in adults and children with NAFLD. METHODS: We measured levels of K18 in stored serum samples collected at baseline and various time points from 231 adults with nonalcoholic steatohepatitis and 152 children with NAFLD who participated in 2 separate prospective randomized clinical trials. Liver biopsy specimens collected at baseline and week 96 were reviewed centrally. RESULTS: There were greater decreases in serum levels of K18 in adults with histologic improvement at week 96 than in those without histologic improvement at week 16 (decrease, 193 ± 293 vs 139 ± 467 U/L; P < .001), week 48 (decrease, 232 ± 360 vs 113 ± 425 U/L; P < .001), or week 96 (decrease, 269 ± 368 vs 97 ± 400 U/L; P < .001). There were greater decreases in serum levels of K18 in children with histologic improvements than in those without histologic improvements at week 48 (decrease, 197 ± 467 vs 47 ± 350 U/L; P = .005) and week 96 (decrease, 206 ± 432 vs 2 ± 474 U/L; P < .001). However, reductions in serum levels of K18 were not better than reductions in levels of alanine aminotransferase in identifying adults with histologic improvement (area under the receiver operator characteristic [AUROC], 0.71; 95% confidence interval [CI], 0.63-0.80; vs AUROC, 0.68; 95% CI, 0.61-0.79; P = .34) or children (AUROC, 0.72; 95% CI, 0.63-0.81; vs AUROC, 0.79; 95% CI, 0.70-0.87; P = .42). CONCLUSIONS: Decreases in serum levels of K18 are associated strongly with improved liver histologies in adults or children with NAFLD. However, reductions in K18 do not perform better than those in alanine aminotransferase level in identifying histologic changes in NAFLD.

Serum high mobility group box 1 protein levels are not associated with either histological severity or treatment response in children and adults with nonalcoholic fatty liver disease.

AIM: Serum high mobility group box 1 protein (HMGB1) is a proinflammatory molecule that could potentially serve as a biomarker for non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) due to its correlation with degree of liver fibrosis. The aim of the current study was to examine the cross-sectional and longitudinal relationships between serum HMGB1 levels and liver histology in adults and children with NAFLD participating in two large randomized controlled trials. METHODS: Serum HMGB1 levels were measured at various time points in adults and children with NAFLD, who participated in PIVENS and TONIC clinical trials respectively. PIVENS trial compared vitamin E or pioglitazone to placebo in adults whereas TONIC trial compared vitamin E or metformin to placebo in children. Participants had liver biopsies at baseline and the end of treatment (96 weeks), and liver histology was reviewed by a central committee of study pathologists. RESULTS: In the cross-sectional analyses (n = 205 for PIVENS and 109 for TONIC), there was no significant relationship between serum HMGB1 levels and histological features such as steatosis, ballooning, inflammation, fibrosis, or presence of steatohepatitis in either adults or children. Serum HMGB1 levels did not change significantly during treatment either with placebo, vitamin E therapy (P = 0.81) or pioglitazone (P = 0.09) in the PIVENS trial. Similarly, serum HMGB1 levels did not change significantly during treatment either with placebo, metformin (P = 0.15) or vitamin E (P = 0.23) in the TONIC trial. In the longitudinal analyses (n = 105 for PIVENS and 109 for TONIC), changes in serum HMGB1 levels did not correlate with histologic improvement or resolution of NASH in either adults or children. There was no relationship between serum HMGB1 and ALT levels in either adults or children with NAFLD. CONCLUSION: Serum HMGB1 levels were not associated with histological severity or treatment response in either children or adults with NAFLD.