P-Selectin (CD62P) Expression in Liver Tissue of Biliary Atresia: A New Perspective in Etiopathogenesis

Advances in understanding of biliary atresia pathogenesis and progression - a riddle wrapped in a mystery inside an enigma

INTRODUCTION

Biliary atresia is a potentially fatal condition of the bile ducts - both intra- and extrahepatic, for which we have no cure. Though principally a cholestatic condition, much of its pathology stems from its tendency to aggressively induce liver fibrosis and ultimately cirrhosis, only partially restrained by the portoenterostomy.

AREAS COVERED

This review is based on the current literature exploring the heterogeneous nature of biliary atresia. Thus, there are various phenotypes or variants of biliary atresia, each potentially with different etiological backgrounds caused by a number of hypothetical pathological mechanisms thought to be important in the genesis of the condition. Search methodology: the review (Oct. - Nov. 2022) is based on a search of PubMed (NLM) using main keyword 'biliary atresia' with supplementary searches using 'fibrosis'; 'inflammation'; 'BASM'; 'genetics'; 'surgery'; 'experimental'; 'etiology'; 'virology'; 'cases'; and 'syndromes.'

EXPERT OPINION

Future developments will be made on matching clinical variants with a more distinct pathophysiological discrimination and those pathways linking the initial cholestatic phase of biliary atresia to the early stages of fibrosis.

Update on Etiology and Pathogenesis of Biliary Atresia

Biliary atresia is a rare inflammatory sclerosing obstructive cholangiopathy that initiates in infancy as complete choledochal blockage and progresses to the involvement of intrahepatic biliary epithelium. Growing evidence shows that biliary atresia is not a single entity with a single etiology but a phenotype resulting from multifactorial events whose common path is obliterative cholangiopathy. The etiology of biliary atresia has been explained as resulting from genetic variants, toxins, viral infection, chronic inflammation or bile duct lesions mediated by autoimmunity, abnormalities in the development of the bile ducts, and defects in embryogenesis, abnormal fetal or prenatal circulation and susceptibility factors. It is increasingly evident that the genetic and epigenetic predisposition combined with the environmental factors to which the mother is exposed are potential triggers for biliary atresia. There is also an indication that a progressive thickening of the arterial middle layer occurs in this disease, suggestive of vascular remodeling and disappearance of the interlobular bile ducts. It is suggested that the hypoxia/ischemia process can affect portal structures in biliary atresia and is associated with both the extent of biliary proliferation and the thickening of the medial layer.

Variant etiologies of neonatal cholestasis and their outcome: a Middle East single-center experience

Aim of the study

Neonatal cholestasis (NC) constitutes a large proportion of pediatric liver disorders. Nevertheless, awareness of the variant etiologies and how to manage them appropriately are lacking. So, out of a few specialized centers, many cases pass without appropriate management. This study aimed to present our tertiary level center’s experience in NC that could increase the pediatrician’s awareness of handling this problematic and common medical morbidity efficiently.

Material and methods

It is a retrospective study in which we analyzed the NC cases admitted to the inpatient department within three years. For all recruited patients, the available data were retrieved and recorded.

Results

A total of 412 patients were reviewed with 20 different etiologies diagnosed. The most common cause was biliary atresia (n = 151, 37%), followed by progressive familial intrahepatic cholestasis (n = 51, 12%), neonatal sepsis (n = 39, 9%), and cytomegalovirus (n = 33, 8%). Of the 412 patients, 394 (81%) had follow-up ranging from 1 to 36 months. A total of 173 patients improved with supportive and/or specific therapy, while 108 patients died at a median age of 6 months. The commonest cause of death was liver failure (40.7%), followed by pneumonia (28.7%), sudden death (13%), septicemia (6.5%), and hepatorenal syndrome (5.5%).

Conclusions

NC constitutes more than one-third of the inpatient admissions of all pediatric liver disorders and has a high rate of mortality. Awareness of the variety of etiologies and a rapid stepwise approach to diagnosis could have an impact on the outcome of this devastating disease.

CD62P (P-selectin) expression as a platelet activation marker in patients with liver cirrhosis with and without cholestasis

AIM OF THE STUDY

P-selectin (CD62P) is a platelet activation marker that was claimed to mediate the accumulation of platelets induced by cholestasis. The nature of platelet dysfunction and hemostasis abnormalities in cholestatic liver disease needs to be more explored. The aim of this study was to assess platelet CD62P expression in cirrhotic patients with and without cholestasis, and to evaluate its relationship with a bleeding tendency.

MATERIAL AND METHODS

150 patients were included in this case-control study. Participants were divided into 84 patients with liver cirrhosis (group I), 44 of whom had cholestasis (Group Ia) and 40 patients were without cholestasis (group Ib); 36 patients who were cholestatic without liver cirrhosis (group II); and 30 healthy subjects who formed the control group (group III). Platelet CD62P expression was assessed by a flow cytometer.

RESULTS

Platelets expressing CD62P were significantly increased in all patient groups compared to controls (p < 0.001). Platelets expressing CD62P were significantly increased in gastrointestinal (GIT) bleeders compared to non-bleeders in cirrhotic and cholestatic groups (p < 0.001 each). Among group I patients at cut-off > 12.4, up-regulation of platelet CD62P yielded 72% sensitivity and 44.1% specificity to discriminate bleeders from non-bleeders (p = 0.01), while among group II at cut-off > 12.9, it yielded 90% sensitivity and 80.8% specificity (p < 0.001). In cirrhotic patients, platelet CD62P expression was significantly increased in patients with an advanced Child-Pugh class (p < 0.001). Platelet expressing CD62P was shown as an independent risk factor for bleeding among cirrhotic cases with an odds ratio of 1.07 and CI 0.99-1.15.

CONCLUSIONS

Up-regulation of platelet CD62P expression can serve as a GIT bleeding predictor in liver cirrhosis.

Preoperative Serum IL-12p40 Is a Potential Predictor of Kasai Portoenterostomy Outcome in Infants with Biliary Atresia

The standard-of-care treatment for biliary atresia (BA) is surgical restoration of bile flow by Kasai portoenterostomy. We aimed to study serum interleukin- (IL-) 12p40, a natural antagonist for the proinflammatory IL-12p70, and its relation to surgical outcomes of BA. The study included 75 infants with neonatal cholestasis: BA group (n = 25), non-BA cholestasis group (n = 30), and neglected BA group (n = 20), in addition to thirty healthy neonates serving as controls. IL-12p40 was measured by ELISA in all individuals and a second assessment was performed 3 months postoperatively in the BA group. The surgical outcomes were classified as successful (bilirubin ≤ 2 mg/dl) or failed (bilirubin > 2 mg/dl). IL-12p40 was higher in BA compared to that in the non-BA and control groups (P values were 0.036 and <0.0001, resp.) but comparable to that in the neglected BA group. Preoperative IL-12p40 levels in BA patients were significantly higher in successful Kasai compared with failed Kasai and a cutoff level of 547.47 pg/ml could predict the successful outcome with 87.5% sensitivity and 82.4% specificity. Three-month postoperative IL-12p40 tended to decrease in both the successful and failed groups. In conclusion, preoperative serum IL-12p40 is a potential predictor of Kasai outcome. Serial postoperative measurements may anticipate the failure of an initially successful operation, hence the need for liver transplantation.

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.