Expression of aminopeptidase N in bile canaliculi: a predictor of clinical outcome in biliary atresia and a potential tool to implicate the mechanism of biliary atresia

Risk Prediction Scoring System to Predict the Postsurgical Outcomes of Biliary Atresia

Aim

To find out association between liver function, liver histopathology and outcomes of biliary atresia (BA) following Kasai Portoenterostomy (KPE).

Materials and Methods

This is a retrospective study of children who underwent KPE at a single institute by single surgeon. The patient records analyzed and data of complete blood counts, liver function tests, coagulation profile and histopathology reports collected. The outcomes recorded as alive and jaundice free, alive but jaundiced, and deceased. Statistical analysis done using SPSS 23.

Observations

Total of 148 children operated during January 2000 to December 2018. Of these, 26 matched inclusion criteria. The parameters assessed were percentage of direct bilirubin, ratios of Aspartate transaminase (AST) to Alanine transaminase (ALT); Gamma glutamyl transferase (GGT) to AST; GGT to ALT and Aspartate transaminase to platelet ratio index (APRi). Among histopathology reports, fibrosis grade and bile ductular size noted. Among 26, 16 alive and ten are deceased. Among 16 alive, all are jaundice free. Of the parameters, ratio of AST to ALT, APRi and grade of fibrosis found statistically significant and further analysis showed if AST to ALT ratio < 2.1, APRi < 1.8 and grade of fibrosis < four, irrespective of age at surgery, had 96.2 % probability of successful KPE. Based on these observations, a scoring system and risk prediction model constructed based on Receiver operating characteristic (ROC) curves which are first in BA management.

Results and Conclusion

Although numbers are sufficient for statistical analysis, we further intend to validate the scoring system in a prospective trial. BA children can be subjected to risk prediction model and KPE performed in those who have a score less than seven and offered to those with score between eight and 16 out of 20.

Key Message

The scoring system and risk prediction model can guide in the management and post-operative follow up of children with biliary atresia.

Prevention of Cell Growth by Suppression of Villin Expression in Lithocholic Acid-Stimulated HepG2 Cells

Cholestasis is a condition wherein bile flow is interrupted and lithocholic acid is known to play a key role in causing severe liver injury. In this study, we performed in-depth analysis of the morphological changes in bile canaliculi and the biological role of villin in cholestasis using lithocholic acid-stimulated HepG2 human hepatocarcinoma cells. We confirmed disruption of the bile canaliculi in liver sections from a liver allograft patient with cholestasis. Lithocholic acid caused strong cytotoxicity in HepG2 cells, which was associated with abnormal morphology. Lithocholic acid reduced villin expression, which recovered in the presence of nuclear receptor agonists. Furthermore, villin mRNA expression increased following small interfering RNA (siRNA)-mediated knockdown of the nuclear farnesoid X receptor and pregnane X receptor. Villin knockdown using siRNA caused cell growth arrest in HepG2 cells. The effect of villin-knockdown on whole-genome expression in HepG2 cells was analyzed by DNA microarray. Our data suggest that lithocholic acid caused cell growth arrest by suppressing villin expression via farnesoid X receptor and pregnane X receptor in HepG2 cells.

A novel rat model simulating biliary atresia after a Kasai operation

PURPOSE

The mechanisms of liver fibrosis in biliary atresia (BA) after a Kasai operation deserve studying to improve the clinical outcomes. This study aimed to create a rat model simulating BA after a Kasai operation.

METHODS

We inserted a polyethylene tube (PE10) into the common hepatic duct (CHD) and ligated the common bile duct (CBD) in 30 newborn rats and injected 95% ethanol into IHD at postoperative week-one (POW-1). The PE10 was removed at POW-3. The rats were sacrificed at POW-5. The CBD cystojejunostomy was performed on another 10 rats at POW-5.

RESULTS

The IHD obliteration and CBD dilatation were noted at POW-3 cholangiography before removal of the PE tube. The gross findings at sacrifice in the rats without cystojejunostomy included biliary fibrosis, CBD cyst, and IHD obliteration. The microscopic findings of the liver were like BA. Seven of the 10 rats with CBD cystojejunostomy were jaundice-free at POW-8. The fibrosis grade at POW-8 of the rats with CBD cystojejunostomy was significantly lower in the jaundice-free rats (Ishak fibrosis score, 3.4 ± 0.9 and 1.5 ± 0.3 in the jaundiced rats and jaundice-free rats, respectively, p < .05).

CONCLUSION

Based on our study, CBD cystojejunostomy five weeks after CBD ligation with ethanol injection into the IHD in newborn rats can provide a model for investigating mechanisms and treatments of liver fibrosis in BA after a Kasai operation.

Significance of alanine aminopeptidase N (APN) in bile in the diagnosis of acute cellular rejection after liver transplantation

BACKGROUND

Allograft dysfunction after liver transplantation requires histopathologic examination for confirmation of the diagnosis, however, the procedure is invasive and its interpretation is not always accurate. The aim of this study was to find novel protein markers in bile for the diagnosis of acute cellular rejection (ACR) after liver transplantation.

MATERIALS AND METHODS

Quantitative proteomic analysis using the (18)O labeling method was used to search for bile proteins of interest. Nine recipients were selected who had liver dysfunction, diagnosed by liver biopsy, either with ACR (ACR group, n = 5) or without (LD group, n = 4). Donor bile samples were obtained from nine independent live liver donors. Enzyme activity in bile samples was assayed and liver biopsy specimens were immunostained for candidate protein of ACR.

RESULTS

The analysis identified 78 proteins, among which alanine aminopeptidase N (APN/CD13) was considered a candidate marker of ACR. Comparative analysis of the ACR and LD groups showed high APN enzyme activity in three (60%) of five cases of the ACR group, while it was as low as donor level in all patients of the LD group. APN enzyme activity in bile samples of liver dysfunction liver transplantation (LDLT) recipients of the ACR group collected within 3 d before biopsy-confirmed ACR (n = 10) was significantly higher (584 ± 434 U/g protein) than in those of recipients free of ACR (n = 96, 301 ± 271 U/g protein) (P = 0.004). APN overexpression along bile canaliculi was observed during ACR in all five cases of the ACR group.

CONCLUSION

APN in bile seems to be a useful and noninvasive biomarker of ACR after liver transplantation.

Identification of novel markers for liver fibrosis in HIV/hepatitis C virus coinfected individuals using genomics-based approach

OBJECTIVE

The degree of liver fibrosis is a determinant for initiation of therapy for hepatitis C virus. Liver biopsy is invasive, risky and costly, but is required to assess fibrosis. This study intended to identify novel noninvasive markers to accurately assess fibrosis in HIV/hepatitis C virus coinfection.

METHODS

Using 100 biopsies from 68 HIV/hepatitis C virus coinfected patients, we developed a predictive model consisting of six serum markers along with age and antiretroviral therapy experience. DNA microarray analysis of peripheral blood mononuclear cells associated with a subset of 51 biopsies obtained from 28 patients was performed and incorporated into a second model.

RESULTS

The eight-marker model yielded an area under the receiver operating characteristic curve of 0.904. Combined analysis of clinical and DNA microarray data in the 51-biopsy subset identified two genes (alanine amino peptidase-N and mitogen-activated protein kinase kinase-3) that predicted fibrosis with high significance. The four-marker model that included the two genes and two serum markers had an area under the receiver operating characteristic curve of 0.852, which did not differ significantly from the eight-marker model on this subset (area under the receiver operating characteristic curve = 0.856, P = 0.96).

CONCLUSION

Both models accurately predicted fibrosis with an accuracy of 87.9%, thereby sparing 83% of patients from obtaining a biopsy. DNA microarray analysis can be invaluable in identifying novel biomarkers of liver fibrosis.

Evaluation of matrix metalloproteinases and their endogenous tissue inhibitors in biliary atresia-associated liver fibrosis

BACKGROUND/PURPOSE

Matrix metalloproteinases (MMPs) and their endogenous tissue inhibitors (TIMPs) are major proteases responsible for remodeling the liver tissue, but their roles in biliary atresia (BA)--associated liver fibrosis are not clear.

METHODS

A DNA microarray containing complementary DNA clones of 10 MMPs and 4 TIMPs was used to compare the expression profiles of the liver cytokines among 3 patients with BA at the time of Kasai procedure (KP) with 3 at the time of liver transplantation (LT). Liver samples from 2 children without liver fibrosis were used as normal controls. Those genes that were differentially expressed by more than 2-fold between groups were further quantified with real time quantitative reverse transcription-polymerase chain reaction (QRT-PCR) and validated with gel electrophoresis.

RESULTS

In normal human liver, messenger RNAs (mRNAs) of TIMP-1, -2, and -3, but not of TIMP-4 and none of the 10 MMPs studied, were expressed in DNA microarray. With progression of liver fibrosis, only mRNA of MMP-7, but not other MMPs, was induced to express at a significantly higher level in the array. Despite its low level of expression, MMP-9 mRNA was significantly upregulated in KP but downregulated in LT, whereas MMP-2, which was not showed in the array, was significantly upregulated in LT than in KP and control in real time QRT-PCR. There was a more than 2-fold increase in TIMP-1 and TIMP-2 mRNA expression in LT over control in the array, which was confirmed in subsequent real time QRT-PCR. The expression of TIMP-3 mRNA was significantly downregulated in KP than in control.

CONCLUSIONS

This study verified differential expression of MMPs and TIMPs in different stages of BA, with emphasis on the role of TIMP-1, -2, and -3 as well as MMP-2, -7, and -9 transcripts in remodeling of liver tissue during the progress of BA-associated liver fibrosis.

Matrilysin (MMP-7) is a major matrix metalloproteinase upregulated in biliary atresia-associated liver fibrosis

Matrix metalloproteinases (MMPs) are the proteases responsible for tissue remodeling during liver fibrosis caused by various disorders including biliary atresia. However, information regarding the relative contribution of these proteases to liver fibrosis is still limited. We studied matrix metalloproteinase-2 (MMP-2), -7, -9 and -13 mRNA expressions in the liver tissue of early-stage biliary atresia at the time of Kasai's procedure, late-stage biliary atresia at the time of liver transplantation with advanced fibrosis and nondiseased control without liver fibrosis. The results of real-time quantitative reverse transcriptase-PCR analysis revealed that only MMP-2 and -7 expressions were significantly different between groups. MMP-2 was significantly higher in Liver Transplantation group than both in Control (P=0.010) and in Kasai's Procedure (P=0.001) groups, whereas the difference of MMP-2 expression between Control and Kasai's Procedure was not significant. However, the relative expression level of MMP-7 was sequentially elevated when comparing Control, Kasai's Procedure and Liver Transplantation groups, and there was significant (P=0.019) difference when comparing Control and Liver Transplantation groups. Moreover, the fold difference in MMP-7 mRNA was much higher than that in MMP-2 mRNA between groups. The expressions of MMP-7 were further confirmed by agarose gel electrophoresis and Western blotting. Immunohistochemical analysis revealed a significant positive correlation of the scores of MMP-7 immunostaining with the stages of liver fibrosis. In situ hybridization demonstrated that the bile ductular epithelial cells, Kupffer cells and hepatocytes were the major producers of matrix metalloproteinase-7 in the liver. Our results imply that MMP-7 is a major MMP associated with the tissue remodeling during the progression of liver fibrosis in biliary atresia.

Immunoglobulin deposits in liver tissue from infants with biliary atresia and the correlation to cytomegalovirus infection

PURPOSE

The aim of this report was to study the amount and distribution of immunoglobulin deposits in liver biopsies from infants with biliary atresia (BA) and correlate the results to the cytomegalovirus (CMV) infection status.

METHODS

Stored liver biopsies from 18 patients with BA and from 6 control patients without liver disease were immunohistochemically stained to detect IgG and IgM deposits. The intensity of the immunoglobulin staining was evaluated by a semiquantitative scoring scale. Ongoing CMV infection was defined as the detection of CMV-IgM in serum and/or the isolation of CMV in the urine and was noted in 9 of the patients with BA.

RESULTS

When analyzing the immunoglobulin deposits on the hepatocellular canalicular membrane the intensity score for IgM deposits was significantly higher in biopsies from patients with BA infected with CMV than in those without. No canalicular staining was detected in control biopsies.

CONCLUSIONS

The results support the possibility that immunologic mechanisms are of importance in the pathogenesis of BA and that a CMV infection may trigger such mechanisms.