Noninvasive markers in the assessment and management of autoimmune liver diseases

Analysis of Differentially Expressed Proteins Involved in Autoimmune Cirrhosis and Normal Serum by iTRAQ Proteomics

PURPOSE

In order to study the candidate biomarkers in autoimmune cirrhosis (AIC).

EXPERIMENTAL DESIGN

Isobaric tags are first implemented for relative and absolute quantitation technology on proteins prepared from serum obtained from AIC and normal controls. Proteins found to be differentially expressed are identified with liquid chromatography electrospray ionization tandem mass spectrometry by using a Q Exactive classic ion trap mass spectrometer.

RESULTS

108 proteins (32 upregulated and 76 downregulated proteins) are identified from AIC samples, compared with the normal controls. Gene Ontology enrichment analysis, KEGG pathway analysis, and protein-protein interaction map by STRING show that they associate with multiple functional groups, including ion binding activity, peptidase activity, and enzyme regulator activity. Finally, the von Willebrand factor, insulin-like growth factor-binding protein complex acid labile subunit, transthyretin, adiponectin proteins are identified with western blot as candidate biomarkers for AIC.

CONCLUSIONS AND CLINICAL RELEVANCE

These findings offer a comprehensive profile of the AIC proteome about candidate biomarkers and provide a useful basis for further analysis of the pathogenic mechanism of AIC.

18F-FAC PET Selectively Images Liver-Infiltrating CD4 and CD8 T Cells in a Mouse Model of Autoimmune Hepatitis

Immune cell-mediated attack on the liver is a defining feature of autoimmune hepatitis and hepatic allograft rejection. Despite an assortment of diagnostic tools, invasive biopsies remain the only method for identifying immune cells in the liver. We evaluated whether PET imaging with radiotracers that quantify immune activation (¹⁸F-FDG and ¹⁸F-1-(2'-deoxy-2'-fluoro-arabinofuranosyl)cytosine [¹⁸F-FAC]) and hepatocyte biology (¹⁸F-2-deoxy-2-fluoroarabinose [¹⁸F-DFA]) can visualize and quantify liver-infiltrating immune cells and hepatocyte inflammation, respectively, in a preclinical model of autoimmune hepatitis. Methods: Mice treated with concanavalin A (ConA) to induce a model of autoimmune hepatitis or vehicle were imaged with ¹⁸F-FDG, ¹⁸F-FAC, and ¹⁸F-DFA PET. Immunohistochemistry, digital autoradiography, and ex vivo accumulation assays were used to localize areas of altered radiotracer accumulation in the liver. For comparison, mice treated with an adenovirus to induce a viral hepatitis were imaged with ¹⁸F-FDG, ¹⁸F-FAC, and ¹⁸F-DFA PET. ¹⁸F-FAC PET was performed on mice treated with ConA and vehicle or with ConA and dexamethasone. Biopsy samples of patients with autoimmune hepatitis were immunostained for deoxycytidine kinase. Results: Hepatic accumulation of ¹⁸F-FDG and ¹⁸F-FAC was 173% and 61% higher, respectively, and hepatic accumulation of ¹⁸F-DFA was 41% lower, in a mouse model of autoimmune hepatitis than in control mice. Increased hepatic ¹⁸F-FDG accumulation was localized to infiltrating leukocytes and inflamed sinusoidal endothelial cells, increased hepatic ¹⁸F-FAC accumulation was concentrated in infiltrating CD4 and CD8 cells, and decreased hepatic ¹⁸F-DFA accumulation was apparent in hepatocytes throughout the liver. In contrast, viral hepatitis increased hepatic ¹⁸F-FDG accumulation by 109% and decreased hepatic ¹⁸F-DFA accumulation by 20% but had no effect on hepatic ¹⁸F-FAC accumulation (nonsignificant 2% decrease). ¹⁸F-FAC PET provided a noninvasive biomarker of the efficacy of dexamethasone for treating the autoimmune hepatitis model. Infiltrating leukocytes in liver biopsy samples from patients with autoimmune hepatitis express high levels of deoxycytidine kinase, a rate-limiting enzyme in the accumulation of ¹⁸F-FAC. Conclusion: Our data suggest that PET can be used to noninvasively visualize activated leukocytes and inflamed hepatocytes in a mouse model of autoimmune hepatitis.

Imaging of autoimmune hepatitis and overlap syndromes

Autoimmune hepatitis (AIH) is an uncommon, chronic inflammatory, and relapsing liver disease of unknown origin that may lead to liver cirrhosis, hepatocellular carcinoma, liver transplantation, or death. AIH occurs in all age groups and races but can frequently manifest as acute fulminant hepatitis. Clinical presentation of AIH can have features similar to primary sclerosing cholangitis (PSC) and primary biliary cirrhosis (PBC), and these diseases may coexist leading to overlap syndromes. Although histological diagnosis is necessary, imaging features often can demonstrate characteristics that may be helpful to distinguish these diseases. Imaging features of AIH are those of chronic liver disease, and imaging plays important role in detection of complications and ruling out other possible causes of chronic liver disease. Emerging techniques such as elastography provide non-invasive options for diagnosis of significant fibrosis and cirrhosis during clinical follow-up as well as assessment of response to treatment. In this study, we will describe imaging findings in AIH and overlap syndromes.

Clinical significance of serum Wisteria floribunda agglutinin positive Mac-2-binding protein level and high-sensitivity C-reactive protein concentration in autoimmune hepatitis

AIM

We aimed to examine the relationship between the Wisteria floribunda agglutinin positive Mac-2-binding protein (WFA(+) -M2BP) level and high-sensitivity C-reactive protein (hCRP) concentration and liver histological findings for patients with autoimmune hepatitis (AIH).

METHODS

A total of 84 AIH patients (median age, 64 years) were analyzed. We examined the effect of pretreatment WFA(+) -M2BP level and hCRP concentration on histological findings of liver fibrosis and liver inflammation activity comparing with other laboratory markers. Receiver-operator curve (ROC) analysis was performed for calculating the area under the ROC (AUROC).

RESULTS

The median WFA(+) -M2BP values in each fibrosis stage were: 1.5 cut-off index (COI) in F1, 2.1 in F2, 3.3 in F3 and 9.8 in F4 (P < 0.001). The median WFA(+) -M2BP values in each liver inflammation stage were: 1.6 COI in A1, 2.5 in A2 and 5.4 in A3 (P < 0.001). For predicting liver cirrhosis (F4), WFA(+) -M2BP yielded the highest AUROC (0.853). For predicting advanced liver fibrosis (F3 or F4), WFA(+) -M2BP, FIB-4 index and hyaluronic acid yielded the highest AUROC (0.747). For predicting severe liver inflammation activity (A3), WFA(+) -M2BP yielded the highest AUROC (0.739). The hCRP concentration in patients with A3 (median, 2230 ng/mL) was significantly higher than that in patients with A1 or A2 (median, 854.5 ng/mL) (P < 0.01). WFA(+) -M2BP level significantly correlated with hCRP concentration (rs  = 0.461, P < 0.001).

CONCLUSION

WFA(+) -M2BP can be a useful marker for assessing liver histological findings in AIH patients and it correlated well with hCRP concentration.