Advances in the clinical use of collagen as biomarker of liver fibrosis

INTRODUCTION

Hepatic fibrosis is the excessive synthesis and deposition of extracellular matrix including collagen in the tissue. Chronic liver insult leads to progressive parenchymal damage, portal hypertension, and cirrhosis. Determination of hepatic collagen by invasive liver biopsy is the gold standard to estimate severity and stage of fibrosis. However, this procedure is associated with pain, carries the risk of infection and bleeding, and is afflicted with a high degree of sampling error. Therefore, there is urgent need for serological collagen-derived markers to assess collagen synthesis/turnover.

AREAS COVERED

Biochemical properties of collagens, cellular sources of hepatic collagen synthesis, and regulatory aspects in collagen expression. Markers are discussed suitable to estimate hepatic collagen synthesis and/or turnover. Discussed studies were identified through a PubMed search done in May 2020 and the authors' topic knowledge.

EXPERT OPINION

Hepatic fibrosis is mainly characterized by accumulation of collagen-rich scar tissue. Although traditionally performed liver biopsy is still standard in estimating hepatic fibrosis, there is evidence that noninvasive diagnostic scores and collagen-derived neo-epitopes provide clinical useful information. These noninvasive tests are less expensive than liver biopsy, better tolerated, safer, and more acceptable to patients. Therefore, these tests will lead to dramatic changes in diagnosis.

Evolving liver inflammation in biochemically normal individuals with anti-mitochondria antibodies

Background

Anti-mitochondria autoantibodies (AMA) occur in > 95% primary biliary cholangitis (PBC) patients. Biochemically normal AMA-positive (BN/AMA+) individuals, occasionally noticed by indirect immunofluorescence (IIF) on HEp-2 cells and confirmed in AMA-specific assays, may represent early stages of PBC. The Enhanced Liver Fibrosis (ELF) score is a surrogate marker for liver fibrosis. This prospective study investigated the ELF score in BN/AMA+ individuals and PBC patients, considering autoantibody avidity and serum levels along the years.

Methods

327 samples from 35 PBC and 59 BN/AMA+ were prospectively obtained in average 3.83 (range 0.50-7.40) years apart. Samples were tested by IIF on rat-kidney (IIF-AMA), western-blot for AMA (WB-AMA), and ELISA for antibodies against pyruvate-dehydrogenase (PDC-E2), gp210, sp100 and CENP-A/B. Anti-PDC-E2 avidity was determined by 6 M urea-elution ELISA. Alkaline phosphatase (ALP), gamma glutamyl transferase (ɣGT) and ELF score were measured by automated methods.

Results

Along the follow-up period BN/AMA+ subjects and PBC patients presented significant increase in serum anti-PDC-E2 (mean 10.45% and 8.86% per year; respectively), anti-PDC-E2 avidity (3.02% and 4.94%/year) and ELF score (3.24% and 2.71%/year). IIF-AMA and ɣGT increased in BN/AMA+ (6.59% and 2.36%) and decreased in PBC (- 4.89%/year and - 3.88%/year). In BN/AMA+ individuals there was positive correlation of ELF with IIF-AMA titer (r = 0.465; p < 0.001) and with anti-PDC-E2 levels (r = 0.239; p < 0.001). Expansion of autoantibody targets along time occurred in 39% BN/AMA+ and 49% PBC patients. The frequency of BN/AMA+ with high probability of having established PBC increased from 7 to 14%.

Conclusions

BN/AMA+ individuals present an orchestrated increase in ELF score and humoral autoimmune response over time, indicating an opportunity for early therapeutic intervention and prevention in autoimmunity.

Effects of hepato-preferential basal insulin peglispro on nuclear magnetic resonance biomarkers lipoprotein insulin resistance index and GlycA in patients with diabetes

AIM

To characterize the effects of hepato-preferential basal insulin peglispro (BIL) and insulin glargine on insulin resistance (lipoprotein insulin resistance index [LP-IR]) and inflammation (GlycA), and to explore the biological implications.

METHODS

This substudy included 847 patients with Type 1 diabetes (T1D) or Type 2 diabetes (T2D) in four cohorts of the BIL development program. LP-IR and GlycA were measured before and after insulin treatment. Correlations between LP-IR, GlycA, clinical parameters and liver biomarkers were assessed.

RESULTS

LP-IR and GlycA were higher in T2D than T1D. LP-IR increased in patients switched from basal insulins to BIL but not in insulin-naive patients. GlycA decreased in T2D patients treated with BIL and T1D patients treated with glargine.

CONCLUSION

These exploratory analyses help to characterize differences in biological effects between BIL and glargine treatment.

Association of fetuin B with markers of liver fibrosis in nonalcoholic fatty liver disease

OBJECTIVE

The liver-derived plasma protein fetuin B is associated with nonalcoholic fatty liver disease (NAFLD) and impaired glucose homeostasis in mice. However, its association with non-invasive ultrasound- and magnetic resonance (MR)-based markers of liver fibrosis and steatosis, the enhanced liver fibrosis (ELF) score, liver biopsy, as well as rs738409 in PNPLA3, has not been elucidated in NAFLD, so far.

DESIGN AND METHODS

The association of circulating fetuin B and transient elastography (TE), controlled attenuation parameter (CAP), ¹H-MR-spectroscopy, the ELF score, liver biopsy, as well as risk alleles in rs738409 in PNPLA3, was studied in 101 NAFLD patients as compared to 15 healthy controls.

RESULTS

Serum fetuin B levels did not differ between NAFLD patients and controls (p = 0.863). Fetuin B was independently and negatively associated with transient elastography liver stiffness measurement (LSM) (p = 0.002), but not with the steatosis markers CAP or ¹H-MR-spectroscopy. Fetuin B serum concentrations were significantly lower in individuals with LSM > 7.0 kPa as compared to patients with LSM < 7.0 kPa (p = 0.024). Furthermore, the ELF score and histologically proven fibrosis were independent and negative predictors of circulating fetuin B. Moreover, serum fetuin B significantly depended on number of rs738409 risk alleles (p = 0.026).

CONCLUSIONS

Fetuin B is independently and negatively associated with non-invasive markers of liver fibrosis and PNPLA3 status in NAFLD patients but does not show a correlation with the hepatic lipid content. Future studies need to elucidate the pathophysiological significance of fetuin B in NAFLD and its potential value as predictor for disease severity.

The Enhanced Liver Fibrosis (ELF) score: normal values, influence factors and proposed cut-off values

BACKGROUND & AIMS

Progressive fibrosis is a major cause of morbidity and mortality in chronic liver disease. To replace liver biopsy for disease staging, multiple serum markers are under evaluation with multiparametric panels yielding the most promising results. The Enhanced Liver Fibrosis (ELF) score is an ECM marker set consisting of tissue inhibitor of metalloproteinases 1 (TIMP-1), amino-terminal propeptide of type III procollagen (PIIINP) and hyaluronic acid (HA) showing good correlations with fibrosis stages in chronic liver disease.

METHODS

The ELF score was measured in 400 healthy controls and 79 chronic hepatitis C patients using an ADVIA Centaur automated system. The ELF score was calculated using the published algorithm combining TIMP-1, PIIINP and HA values. Patients' fibrosis stage was defined histologically. ROC analyses were performed to study marker validity. Reference values and influence factors for the ELF score were validated.

RESULTS

ELF score reference values ranged from 6.7 to 9.8 and were significantly higher for men vs. women (7.0-9.9 vs. 6.6-9.3, respectively). Afternoon values were slightly higher than morning values (6.7-9.9 vs. 6.6-9.5, respectively). Age was a notable influence factor. We identified three cut-off values: 7.7 for a high sensitivity exclusion of fibrosis, 9.8 for a high specificity identification of fibrosis (sensitivity 69%, specificity 98% for moderate fibrosis), and 11.3 to discriminate cirrhosis (sensitivity 83%, specificity 97%). ELF score validity was superior to the results of the single tests.

CONCLUSIONS

The ELF score can predict moderate fibrosis and cirrhosis. However, influence factors such as gender and age need to be taken into account.