Elevated expression of IL2 is associated with increased infiltration of CD8+ T cells in biliary atresia

New insights in understanding biliary atresia from the perspectives on maternal microchimerism

Biliary atresia (BA) is a fibroinflammatory cholangiopathy and portal venopathy. It is of unknown etiology and is associated with systemic immune dysregulation, in which the first insult begins before birth. Maternal microchimerism is a naturally occurring phenomenon during fetal life in which maternal alloantigens promote the development of tolerogenic fetal regulatory T-cells in utero. However, maternal cells may alter the fetus's response to self-antigens and trigger an autoimmune response under certain histocompatibility combinations between the mother and the fetus. A recent report on a set of dizygotic discordant twins with BA, one of whose placentae showed villitis of unknown etiology, implies a certain immune-mediated conflict between the fetus with BA and the mother. Maternal chimeric cells persist postnatally for various time spans and can cause cholangitis, which ultimately leads to liver failure. In contrast, patients who eliminate maternal chimeric cells may retain their liver function.

ANKRD1 and SPP1 as diagnostic markers and correlated with immune infiltration in biliary atresia

The diagnosis of biliary atresia (BA) remains a clinical challenge, reliable biomarkers that can easily distinguish BA and other forms of intrahepatic cholestasis (IC) are urgently needed.Differentially expressed genes were identified by R software. The least absolute shrinkage and selection operator regression and support vector machine algorithms were used to filter the diagnostic biomarkers of BA. The candidate biomarkers were further validated in another independent cohort of patients with BA and IC. Then CIBERSORT was used for estimating the fractions of immune cell types in BA. Gene set enrichment analyses were conducted and the correlation between diagnostic genes and immune cells was analyzed.A total of 419 differentially expressed genes in BA were detected and 2 genes (secreted phosphoprotein 1 [SPP1] and ankyrin repeat domain [ANKRD1]) among them were selected as diagnostic biomarkers. The SPP1 yielded an area under the curve (AUC) value of 0.798 (95% confidence interval [CI]: 0.742-0.854) to distinguish patients with BA from those with IC, and ANKRD1 exhibited AUC values of 0.686 (95% CI: 0.616-0.754) in discriminating BA patients and those with IC. Further integrating them into one variable resulted in a higher AUC of 0.830 (95% CI: 0.777-0.879). The regulatory T cells, M2 macrophages cells, CD4 memory T cells, and dendritic cells may be involved in the BA process. The ANKRD1 and SPP1 was negatively correlated with regulatory T cells.In conclusion, the ANKRD1 and SPP1 could potentially provide extra guidance in discriminating BA and IC. The immune cell infiltration of BA gives us new insight to explore its pathogenesis.

Biliary atresia: pathology, etiology and pathogenesis

Biliary atresia is a progressive fibrosing obstructive cholangiopathy of the intrahepatic and extrahepatic biliary system, resulting in obstruction of bile flow and neonatal jaundice. Histopathological findings in liver biopsies include the expansion of the portal tracts, with edematous fibroplasia and bile ductular proliferation, with bile plugs in duct lumen. Lobular morphological features may include variable multinucleate giant cells, bilirubinostasis and hemopoiesis. The etiopathogenesis of biliary atresia is multifactorial and multiple pathomechanisms have been proposed. Experimental and clinical studies have suggested that viral infection initiates biliary epithelium destruction and release of antigens that trigger a Th1 immune response, which leads to further injury of the bile duct, resulting in inflammation and obstructive scarring of the biliary tree. It has also been postulated that biliary atresia is caused by a defect in the normal remodelling process. Genetic predisposition has also been proposed as a factor for the development of biliary atresia.

MicroRNA-499 Rs3746444 polymorphism and biliary atresia

BACKGROUND

Single nucleotide polymorphisms within microRNAs are known to affect the risk in development and prognosis of many diseases. This study was designed to investigate whether polymorphism of microRNA-499 (miR-499, rs3746444 A>G) is associated with risk to biliary atresia (BA).

METHODS

A hospital-based cases-control study was performed on a total of 507 Han Chinese (207 BA cases and 300 ethnically-matched healthy controls without any evidence of liver diseases) so as to analyze the association between miR-499 rs3746444 polymorphism and BA risk as well as liver function remission (LFR) after liver transplantation.

RESULTS

A significant higher frequency of the rs3746444 G alleles was found in the BA cases than the control group (odd ratio, 1.55, 95% confidence intervals [CIs], 1.15-2.10). This polymorphism was also observed to correlate with some clinic-pathological features of BA cases such as liver inflammatory. Further research found both higher levels of IL-6 (P<0.05) and TNF-α (P<0.05) in removed liver as well as in serum. What is more, the miR-499 rs3746444 polymorphism significantly affected the status of LFR (hazard ratio, 1.37; 95% CI, 1.08-1.83).

CONCLUSIONS

MiR-499 (rs3746444) gene polymorphisms may be genetic determinants for increased risk of BA and prolonged recovery of BA patients after liver transplantation in Han Chinese.

Significant hepatic expression of IL-2 and IL-8 in biliary atresia compared with other neonatal cholestatic disorders

OBJECTIVES

Although the exact etiology of biliary atresia (BA) is still elusive, inflammation plays a key role. Release of proinflammatory cytokines from activated immune cells perpetuates the injury and causes biliary destruction. We aimed to study interleukin (IL)-2 and IL-8 expression in liver tissue of BA patients compared with other neonatal cholestatic disorders.

METHODS

The study included 59 infants with neonatal cholestasis in two groups; BA group (n=31) and non-BA group (n=28) with cholestatic disorders other than BA as controls. Demographic, clinical, laboratory, and histopathological parameters were collected. IL-2 and IL-8 immunostaining was performed. Immunostaining in portal cellular infiltrate was scored as positive or negative and expressed as the mean cell count in three portal tracts.

RESULTS

The mean value of IL-2 and IL-8 positive inflammatory cells was significantly higher in BA than in non-BA group (P-values of 0.004 and 0.002 respectively). IL-2 correlated significantly with IL-8 immunostaining in both BA and non-BA group (P<0.0001 for both). Furthermore, both cytokines in both groups correlated significantly with inflammatory activity in liver biopsy while there was no significant correlation with the other studied parameters. Yet, there was a trend of increased expression of IL-2 and IL-8 with increasing stage of fibrosis in BA group. This trend was not observed in non-BA group.

CONCLUSION

The significantly higher expression of IL-2 and IL-8 in patients with BA compared to non-BA suggests a potential role for these cytokines in the pathogenesis in therapy of this devastating neonatal hepatic disorder.

The correlation between plasma cytokine levels in jaundice-free children with biliary atresia

BACKGROUND

T helper (Th) cell cytokines modulate inflammation and play a role in biliary atresia (BA). The aim of the study is a cross-sectional assessment of the levels of Th cytokines in the jaundice-free post Kasai procedure patients.

METHODS

There were 40 jaundice-free patients with BA and 28 normal controls enrolled. Patients were divided into 3 groups, including normal liver function, impaired liver function, and portal hypertension. Plasma concentration of Th1 [interferon-γ (INF-γ), interleukin (IL)-2], Th2 (IL-4, IL-10), Th3 [transforming growth factor-β1 (TGF-β1)], Th17 (IL-17) cytokines, and stromal cell-derived factor-1α (SDF-1α) were investigated.

RESULTS

The IFN-γ level was significantly higher in the BA patients with impaired liver function and portal hypertension than controls (P<0.0001 and P<0.0001, respectively). There was a significantly increase of TGF-ß1 in all BA groups compared with controls (P=0.003). The reduction of SDF-1α expression was found in BA groups (P<0.0001). IL-10 levels significantly correlated with aspartate aminotransferase to platelet ratio index (r=0.496, P=0.001). For the cytokine correlations, there were no correlations of Th1, Th2 and Th17 cytokine with the other measured cytokines, but TGF-ß1 was negatively correlated with SDF-1α levels (r=-0.327, P=0.039).

CONCLUSIONS

IFN-γ and IL-10 are likely to be involved in the disease progression in BA. Besides, TGF-β1 is found to be a suppression marker associated with SDF-1α levels and reduced production of TGF-β1 may be associated with the disease progression.

The inflammatory phenotype of the fibrous plate is distinct from the liver and correlates with clinical outcome in biliary atresia

Biliary atresia is an inflammatory cholangiopathy of still undetermined etiology. Correlations between histologic findings and clinical outcome in this disease have largely been based on evaluation of liver parenchyma. This study aimed to characterize the pattern of inflammation within the biliary remnant and identify associations between the type and degree of inflammation and clinical outcome as reflected by the transplant-free interval. The inflammation within the fibrous plates and livers of 41 patients with biliary atresia was characterized using immunohistochemical markers and the cell populations were digitally quantified. The type and quantity of cells within the infiltrate were then correlated with length of time from Kasai portoenterostomy until transplant. Histologic and immunohistochemical features of the biliary remnant allowed stratification of patients into "inflammatory plate" and "fibrotic plate" groups. Overall there was no significant difference in transplant-free interval between the two cohorts; however, there was a trend towards a longer time to transplant among patients in the "fibrotic plate" group. In addition, the composition of the inflammatory infiltrate in the fibrous plate was distinctly different from that present in the liver and only the characteristics of the inflammation in the fibrous plate, in particular the number of Foxp3+ T regulatory lymphocytes correlated with clinical outcome. The results of this study support the view of the extra-hepatic biliary tree as the primary site of injury in BA with the changes seen in the liver as secondary manifestations of outflow obstruction. The association between specific inflammatory cell subtypes within the fibrous plate and the length of transplant-free interval also supports the role of the immune system in the initial process of bile duct damage in biliary atresia.

Aetiology of biliary atresia: what is actually known?

Biliary atresia (BA) is a rare disease of unknown etiology and unpredictable outcome, even when there has been timely diagnosis and exemplary surgery. It has been the commonest indication for liver transplantation during childhood for the past 20 years. Hence much clinical and basic research has been directed at elucidating the origin and pathology of BA. This review summarizes the current clinical variations of BA in humans, its occasional appearance in animals and its various manifestations in the laboratory as an experimental model.

The effects of hyperbaric oxygen application against cholestatic oxidative stress and hepatic damage after bile duct ligation in rats

BACKGROUND

The aim of this study was to evaluate the preventive and therapeutic potential of hyperbaric oxygen therapy (HBO) on the liver tissue against bile duct ligation (BDL)-induced oxidative damage and fibrosis in rats.

MATERIALS AND METHODS

We divided 32 adult male Sprague Dawley rats into four groups: sham, sham plus HBO, BDL, and BDL plus HBO; each group contained eight animals. We placed the sham plus HBO and BDL plus HBO groups in an experimental hyperbaric chamber in which we administered pure oxygen at 2.5 atmospheres absolute 100% oxygen for 90 min on 14 consecutive days.

RESULTS

The application of BDL clearly increased the tissue malondialdehyde level, myeloperoxidase activity, and hydroxyproline content and decreased the antioxidant enzymes (superoxide dismutase and catalase activities) and glutathione level. Hyperbaric oxygen therapy treatment significantly decreased the elevated tissue malondialdehyde level, myeloperoxidase activity, and hydroxyproline content and increased the reduced superoxide dismutase and catalase activities and glutathione level in the tissues. The changes demonstrating the bile duct proliferation and fibrosis in expanded portal tracts include the extension of proliferated bile ducts into lobules, mononuclear cells, and neutrophil infiltration into the widened portal areas were observed in BDL group. Treatment of BDL with HBO attenuated alterations in liver histology. Alpha smooth muscle actin, cytokeratin-positive ductular proliferation, and the activity of terminal deoxynucleotidyl transferase 2'-deoxyuridine, 5'-triphosphate nick end labeling in the BDL decreased with HBO treatment.

CONCLUSIONS

The data indicate that HBO attenuates BDL-induced oxidative injury, hepatocytes damage, bile duct proliferation, and fibrosis. The hepatoprotective effect of HBO is associated with antioxidative potential.

Biliary atresia: a multidisciplinary approach to diagnosis and management

CONTEXT

Biliary atresia is an inflammatory cholangiopathy of infancy that results in progressive fibrosis and obliteration of bile ducts and represents the main indication for liver transplant in young children. In spite of extensive investigation, its etiology has remained poorly understood. Timely surgical intervention (Kasai procedure) may result in significant benefit to these patients and represents the final goal of an accurate diagnostic evaluation.

OBJECTIVE

To present an overview of biliary atresia, including clinical and surgical approaches to this disease, with emphasis on the histopathologic evaluation.

DATA SOURCES

Review of relevant literature indexed in PubMed (US National Library of Medicine).

CONCLUSION

A well-coordinated multidisciplinary approach is required in the assessment of suspected cases of biliary atresia. Pathologic examination of biopsy specimens is an integral part of the diagnostic algorithm and, therefore, plays a pivotal role in the diagnostic evaluation of this disease.

Susceptibility to experimental biliary atresia linked to different hepatic gene expression profiles in two mouse strains

AIM

To compare hepatic gene expression during the development of experimental biliary atresia (BA) in two different mouse strains.

METHODS

Balb/c mice and C57Black/6 (Black/6) mice were infected with rhesus rotavirus (RRV) postpartum, clinical signs of BA and survival were noted. Liver sections were assessed for cluster of differentiation antigen (CD) 3, CD4 and CD8 expression, and the hepatic virus load was determined. Second, mice of both strains were sacrificed three days after infection. Isolated hepatic RNA was subjected to gene expression analysis using Affymetrix Gene Chip MOE 430 2.0.

RESULTS

The incidence of BA was significantly lower in Black/6 mice compared to Balb/c mice (13.5% vs. 67%, P < 0.05). The mean virus titers were higher in mice with BA compared to mice without BA. Different gene profiles three days after virus infection were noted, with differential expression of 201 genes, including those regulating apoptosis, nucleic acid binding, transport function and particularly the immune response (chemokine C-C motif ligand 2, toll-like receptor 3, CD antigen 14, chemokine (C-X-C motif) ligands 10 and 11). This correlated with a significant increase of CD4 positive cells only in Balb/c mice with BA compared to healthy mice (13.5 vs. 5.0; P < 0.05). Black/6 mice did not exhibit any significant increase of CD3 or CD4 leukocytes despite cholestasis.

CONCLUSION

The different susceptibility to experimental BA was associated with an increase of CD4 T-cells in the liver of Balb/c mice, which is linked to different gene profiles at the onset of bile duct obstruction.

Biliary atresia: a new immunological insight into etiopathogenesis

Biliary atresia is an idiopathic neonatal cholestatic disease characterized by the destruction of both the intra- and extra-hepatic biliary ducts. There are two clinical manifestations of the disease: an embryonal subtype, which often presents at birth and is associated with congenital malformations, and a 'perinatal' subtype, which is probably an acquired disease due to unknown etiology. Over the last two decades, researchers have focused on activation of the cell-mediated immunity as the mechanism for biliary epithelial cell destruction for the latter subtype. A proposed trigger of this immune response is an initial viral infection, inducing biliary epithelial cells to become antigen-presenting cells and thus instigating immune-mediated destruction of the biliary tract. However, putative viruses have never been confirmed. More recently, a novel hypothesis - that maternal microchimerism may initiate a host immunologic response towards the bile duct epithelia - has been proposed. This paper discusses the etiology of biliary atresia in the context of the current research.

Maternal microchimerism in underlying pathogenesis of biliary atresia: quantification and phenotypes of maternal cells in the liver

OBJECTIVE

The goal was to examine whether microchimerism plays a crucial role in the pathogenesis of biliary atresia; we analyzed the localization of maternal microchimeric cells and their phenotypes.

METHODS

Liver biopsy specimens from 8 male infants with biliary atresia and 6 control subjects with other liver diseases were investigated for maternal chimeric cells and their phenotypes through double-staining fluorescence in situ hybridization and immunohistochemical analyses.

RESULTS

Significantly larger numbers of maternal XX+ cells were found in the portal area and sinusoids of patients with biliary atresia, in comparison with control patients. In phenotypic analyses of XX+ cells, CD8+ T cells, CD45+ cells, and cytokeratin-positive cells were found, and the numbers and proportions among total CD8+ T cells were significantly higher than those in control patients.

CONCLUSIONS

Significantly more maternal chimeric CD8+ T cells in the livers of patients with biliary atresia suggest that maternal immunologic insults represent the underlying pathogenesis in biliary atresia. The findings support the recently postulated mechanisms of alloautoimmune and/or autoalloimmune responses.

Randomized, double-blind, placebo-controlled trial of corticosteroids after Kasai portoenterostomy for biliary atresia

The objective of this study was to evaluate adjuvant corticosteroids after Kasai portoenterostomy for biliary atresia. The study consisted of a prospective, 2-center, double-blind, randomized, placebo-controlled trial of post-Kasai portoenterostomy corticosteroids (oral prednisolone: 2 mg/kg/day from day 7 to day 21 and 1 mg/kg/day from day 22 to day 28). The data were compared with chi2 or Mann-Whitney tests, as appropriate. Seventy-one postoperative infants with type 3 biliary atresia were randomized to receive either oral prednisolone (n = 36) or a placebo (n = 37). At 1 month, the median bilirubin level was lower in the steroid group (66 versus 92 micromol/L, P = 0.06), but no difference was evident at 6 (P = 0.56) or 12 (P = 0.3) months. The proportion of infants with a normal bilirubin level (<20 micromol/L) at 6 (47% versus 49%, P = 0.89) and 12 months (50% versus 40%, P = 0.35) was not significantly different. The need for transplantation by 6 (12% versus 13%, P = 0.99) and 12 months (26% versus 35%, P = 0.47) was not significantly different. The steroid effect was more pronounced in younger infants (less than 70 days at Kasai portoenterostomy, n = 51), with a reduced bilirubin level at 1 month (64 versus 117 micromol/L, P = 0.01) and with a greater proportion with a normal bilirubin level at 12 months (54% versus 37%, P = 0.22).

CONCLUSION

There was a beneficial effect on the rate of reduction of bilirubin in the early postoperative period (specifically in infants less than 70 days old at surgery), but this steroid regimen did not reduce the need for liver transplantation.

Serial circulating markers of inflammation in biliary atresia--evolution of the post-operative inflammatory process

Biliary atresia (BA) may be characterized as an occlusive cholangiopathy affecting both intra- and extra-hepatic parts of the biliary tree, together with a pronounced inflammatory response consisting of hepatic infiltration of (predominantly) CD4+ lymphocytes and macrophages. Soluble cellular adhesion molecules are also known to be raised at the time of portoenterostomy, presumably reflecting intrahepatic disease. We investigated this measurable inflammatory component longitudinally by studying a panel of cellular adhesion molecules (soluble intercellular adhesion molecule-1 [sICAM-1], soluble vascular cell adhesion molecule-1 [sVCAM-1]) and soluble proinflammatory mediators (T helper 1 [interleukin [IL]-2 and interferongamma] and T helper 2 [IL-4 and IL-10]) cytokines and macrophage markers (tumor necrosis factor [TNF] alpha and IL-18) in 21 consecutive infants with BA post-Kasai portoenterostomy (KP). The levels of all adhesion molecules and cytokines (except IL-10) increased progressively by 6 months post-portoenterostomy. The response was non-polarized but with 100-fold increases in IL-2, TNFalpha and IL-18 particularly but only modest elevations in IL-10. When proinflammatory profiles were related to outcome, we found poor discrimination if assessed as clearance of jaundice but markedly higher values for IL-2, interferongamma, IL-4, IL-10, TNFalpha and sICAM-1 for those who would be transplanted by 1 year. Using ROC curve analysis for sICAM-1 levels at 1 month post-KP, a cutoff level of 1,779 ng/ml was determined to predict the need for transplantation at 1 year with 92% specificity and 87% sensitivity.

CONCLUSION

The early circulating inflammatory process in BA is persistent, progressive and involves a non-polarized T cell, macrophage and cell adhesion molecule response only partially ameliorated by KP.

Hepatic damage in biliary-obstructed rats is ameliorated by leflunomide treatment

Cholestasis, or impaired bile flow, occurs in a wide variety of liver diseases and causes hepatic damage by retention and accumulation of toxic hydrophobic bile salts inducing persistent inflammation and oxidative stress. In the present research, we studied the effect of leflunomide, a novel immunosuppressive and anti-inflammatory agent against autoimmune disease, on hepatic damage produced by double ligature of the extrahepatic biliary duct in Wistar Albino rats. Cholestasis was done by double ligature and section of the extrahepatic biliary duct (BDL). Leflunomide was given i.g. 10 mg/kg/day. The severity of cholestasis and hepatic injury was determined by changes in the plasma enzyme activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and levels of direct bilirubin. Malondialdehyde (MDA), protein carbonyl (PC), nitric oxide (NO), catalase (CAT) and superoxide dismutase (SOD) were determined to the oxidative status in the liver tissue. Myeloperoxidase (MPO) activity and levels of tissue hydroxyproline (HPR) were determined to neutrophil activation and collagen accumulation, respectively. Further, histological changes were studied. Treatment with leflunomide markedly reduced serum transaminase activities as compared to BDL rats. At the same time leflunomide significantly inhibited increases in liver MDA, PC and NO levels and also attenuated the depletion of CAT and SOD in the liver after bile duct ligation. Similarly, increase in tissue MPO activity and HPR due to BDL was also attenuated by leflunomide treatment. These findings were supported by histopathological findings. These findings suggested that leflunomide can attenuate hepatic damage in extrahepatic cholestasis by prevention of oxidative stress and inflammatory process.