Recent updates on progressive familial intrahepatic cholestasis types 1, 2 and 3: Outcome and therapeutic strategies

Molecular basis of progressive familial intrahepatic cholestasis 3. A proteomics study

Progressive familial intrahepatic cholestasis type 3 (PFIC3) is a severe rare liver disease that affects between 1/50,000 and 1/100,000 children. In physiological conditions, bile is produced by the liver and stored in the gallbladder, and then it flows to the small intestine to play its role in fat digestion. To prevent tissue damage, bile acids (BAs) are kept in phospholipid micelles. Mutations in phosphatidyl choline transporter ABCB4 (MDR3) lead to intrahepatic accumulation of free BAs that result in liver damage. PFIC3 onset usually occurs at early ages, progresses rapidly, and the prognosis is poor. Currently, besides the palliative use of ursodeoxycholate, the only available treatment for this disease is liver transplantation, which is really challenging for short-aged patients. To gain insight into the pathogenesis of PFIC3 we have performed an integrated proteomics and phosphoproteomics study in human liver samples to then validate the emerging functional hypotheses in a PFIC3 murine model. We identified 6246 protein groups, 324 proteins among them showing differential expression between control and PFIC3. The phosphoproteomic analysis allowed the identification of 5090 phosphopeptides, from which 215 corresponding to 157 protein groups, were differentially phosphorylated in PFIC3, including MDR3. Regulation of essential cellular processes and structures, such as inflammation, metabolic reprogramming, cytoskeleton and extracellular matrix remodeling, and cell proliferation, were identified as the main drivers of the disease. Our results provide a strong molecular background that significantly contributes to a better understanding of PFIC3 and provides new concepts that might prove useful in the clinical management of patients.

Simultaneous total internal biliary diversion during liver transplantation for progressive familial intrahepatic cholestasis type 1: Standard of care?

Patients post liver transplant (LT) with progressive familial intrahepatic cholestasis type 1 (PFIC-1) often develop progressive graft steatohepatitis, intractable diarrhea, and growth failure. A total internal biliary diversion (TIBD) during an LT may prevent or reverse these adverse events. Children with PFIC-1 who underwent an LT at our institute were divided into 2 groups, A and B based on the timeline where we started offering a TIBD in association with LT. Pre-LT parameters, intraoperative details, and posttransplant complications like graft steatosis and diarrhea were also analyzed between the 2 groups, and their growth velocity was measured in the follow-up period. Of 550 pediatric LT performed between 2011 and 2022, 13 children underwent LT for PFIC-1. Group A had 7 patients (A1-A7) and group B had 6 (B1-B6). Patients A1, A4, B4, and B5 had a failed partial internal biliary diversion before offering them an LT. Patients A1, A2, and A6 in group A died in the post-LT period (2 early allograft dysfunction and 1 posttransplant lymphoproliferative disorder) whereas A3, A4, and A5 had graft steatosis in the follow-up period. A4 was offered a TIBD 4 years after LT following which the graft steatosis fully resolved. In group B, B1, B2, B5, and B6 underwent TIBD during LT, and B3 and B4 had it 24 and 5 months subsequently for intractable diarrhea and graft steatosis. None of the patients in group B demonstrated graft steatosis or diarrhea and had good growth catch-up during follow-up. We demonstrate that simultaneous TIBD in patients undergoing LT should be a standard practice as it helps dramatically improve outcomes in PFIC-1 as it prevents graft steatosis and/or fibrosis, diarrhea, and improves growth catch-up.

Pediatric Cholestatic Diseases: Common and Unique Pathogenic Mechanisms

Cholestasis is the predominate feature of many pediatric hepatobiliary diseases. The physiologic flow of bile requires multiple complex processes working in concert. Bile acid (BA) synthesis and excretion, the formation and flow of bile, and the enterohepatic reuptake of BAs all function to maintain the circulation of BAs, a key molecule in lipid digestion, metabolic and cellular signaling, and, as discussed in the review, a crucial mediator in the pathogenesis of cholestasis. Disruption of one or several of these steps can result in the accumulation of toxic BAs in bile ducts and hepatocytes leading to inflammation, fibrosis, and, over time, biliary and hepatic cirrhosis. Biliary atresia, progressive familial intrahepatic cholestasis, primary sclerosing cholangitis, and Alagille syndrome are four of the most common pediatric cholestatic conditions. Through understanding the commonalities and differences in these diseases, the important cellular mechanistic underpinnings of cholestasis can be greater appreciated.

Outcomes of pediatric liver transplantation for progressive familial intrahepatic cholestasis

BACKGROUND

Progressive familial intrahepatic cholestasis (PFIC) is a heterogenous group of inherited hepatocellular disorders and the clinical aspects, role of liver transplantation (LT), and its outcomes remain largely unelucidated. We present our data of LT for each type of PFIC and compare their early, and long-term outcomes, highlighting their individual differences and management strategies.

METHODS

Prospectively collected data over a decade (2011-2022) of children with PFIC who underwent LT was analyzed. The groups (PFIC 1-4) were compared with regard to early and long-term outcomes including attainment of catch-up growth.

RESULTS

Of 60 children with PFIC who underwent LT, 13, 11, 31 & 5 were of PFIC 1, 2, 3 & 4, respectively. There were no significant differences in gender, PELD scores, BMI, type of grafts, cold and warm ischemia times, intraoperative blood loss, and morbidity among the groups. Post-LT chronic diarrhea was observed in 6 (46.1%) children with PFIC-I, and of them, 3 (23%) developed graft steatohepatitis. Three of these children underwent total internal biliary diversion (TIBD) and on 1-year follow-up, their graft steatosis resolved and they attained catch-up growth. Catch-up growth was significantly poorer in the PFIC1 group (44.4% vs. 88%, 90%, 100% p < .001). Overall 1- and 5-year patient survival of the four PFIC groups (1-4) were 69.2%, 81.8%, 96.8%, 100% & 69.2%, 81.8%, 96.8%, 100%, respectively.

CONCLUSION

Ours is the largest to-date series of LT for PFIC illustrating their short- and long-term outcomes. While the results for the whole cohort were excellent, those after LT for PFIC1 was relatively poorer as reflected by catch-up growth, graft steatosis, and post-LT diarrhea, which can be optimized by the addition of TIBD during LT.

Progressive Familial Intrahepatic Cholestasis: A Descriptive Study in a Tertiary Care Center

Background

Progressive familial intrahepatic cholestasis (PFIC) is a rare genetic disorder that results from defective mechanisms of bile secretion. We aim to describe different types of PFIC and their clinical features, treatment modalities, and outcomes in Saudi Arabia. Patients and Methods. This is a retrospective study of all patients diagnosed with PFIC at King Faisal Specialist Hospital and Research Center in Riyadh from January 1, 2002, to December 31, 2021. All relevant information was collected from patient charts and transferred into the REDcap® database for statistical analysis.

Results

A total of 79 patients were identified with PFIC, and PFIC type 3 was the most common (59.5%), followed by PFIC type 2 (34.2%), PFIC type 1 (5.1%), and PFIC type 4 (1.3%). Males and females were affected in 54.4% and 45.6%, respectively. Mutations in ATP8B1, ABCB11, and ABCB4 genes were observed in PFIC type 1, PFIC type 2, and PFIC type 3, and loss of function in a variant of TJP2 was detected in PFIC type 4, respectively. A total of 51 (64.6%) patients underwent liver transplantation: three patients (3/4) with PFIC type 1 (75%), twenty patients (20/27) with PFIC type 2 (74.1%), twenty-seven patients (27/47) with PFIC type 3 (57.4%), and one patient with PFIC type 4 (100%). The mean duration of disease before transplantation was 53.9 ± 67 months with a median of 30 months. Following liver transplantation, symptomatic control was achieved in 47 patients (92.2%). Recurrence after transplantation occurred in 4 patients (7.8%) within an average of 22.5 months and a median of 17 months.

Conclusion

PFIC is considered a rare disorder in Saudi Arabia; however, early recognition of the disease is important for appropriate management and early referral for liver transplantation evaluation. The overall rate of liver transplantation in our cohort was 64.6% with an excellent five-year survival rate.

Cholestasis: exploring the triangular relationship of gut microbiota-bile acid-cholestasis and the potential probiotic strategies

Cholestasis is a condition characterized by the abnormal production or excretion of bile, and it can be induced by a variety of causes, the factors of which are extremely complex. Although great progress has been made in understanding cholestasis pathogenesis, the specific mechanisms remain unclear. Therefore, it is important to understand and distinguish cholestasis from different etiologies, which will also provide indispensable theoretical support for the development of corresponding therapeutic drugs. At present, the treatment of cholestasis mainly involves several bile acids (BAs) and their derivatives, most of which are in the clinical stage of development. Multiple lines of evidence indicate that ecological disorders of the gut microbiota are strongly related to the occurrence of cholestasis, in which BAs also play a pivotal role. Recent studies indicate that probiotics seem to have certain effects on cholestasis, but further confirmation from clinical trials is required. This paper reviews the etiology of and therapeutic strategies for cholestasis; summarizes the similarities and differences in inducement, symptoms, and mechanisms of related diseases; and provides information about the latest pharmacological therapies currently available and those under research for cholestasis. We also reviewed the highly intertwined relationship between gut microbiota-BA-cholestasis, revealing the potential role and possible mechanism of probiotics in the treatment of cholestasis.

Clinical and genetic characterization of pediatric patients with progressive familial intrahepatic cholestasis type 3 (PFIC3): identification of 14 novel ABCB4 variants and review of the literatures

BACKGROUND

Progressive familial intrahepatic cholestasis type 3 (PFIC3) is an autosomal recessive disease caused by pathogenic variants of the gene ABCB4. This study aimed to investigate the ABCB4 genotypic and the clinical phenotypic features of PFIC3 patients.

METHODS

The clinical and molecular genetic data of 13 new pediatric patients with PFIC3 as well as 82 reported ones in the PubMed and CNKI databases were collected and analyzed.

RESULTS

The 13 new PFIC3 patients included six females and seven males, and the main presentations were hepatomegaly, splenomegaly, jaundice, and pruritus, as well as increased levels of gamma-glutamyl transpeptidase (GGT). Fourteen new ABCB4 variants were detected, including eight diagnosed to be likely-pathogenic and six, pathogenic. Among all the 95 PFIC3 cases, hepatomegaly was observed in 85.3% (81/95), pruritus in 67.4% (64/95), splenomegaly in 52.6% (50/95), jaundice in 48.4% (46/95), portal hypertension in 34.7% (33/95) and GGT elevation in 100% (88/88) of the patients. Positive responses at varied degrees to oral ursodeoxycholic acid (UDCA) treatment were observed in 66.1% (39/59) of the patients, among whom 38.5% (15/39) fully recovered in terms of the laboratory changes. Although the condition remained stable in 53 patients (58.9%, 53/90), the clinical outcomes were not promising in the rest 37 cases (41.1%, 37/90), including 7 died, 27 having undergone while another 3 waiting for liver transplantation. A total of 96 ABCB4 variants were detected in the 95 patients. PFIC3 patients with biallelic null variants exhibited earlier onset ages [10.5 (2, 18) vs. 19 (8, 60) months, p = 0.007], lower UDCA response rate [18.2% (2/11) vs. 77.1% (37/48), p = 0.001], and more unpromising clinical outcomes [80% (12/15) vs. 33.3% (25/75), p = 0.001], compared with those with non-biallelic null variants.

CONCLUSIONS

PFIC3 presented with hepatomegaly, pruritus, splenomegaly and jaundice with increased serum GGT level as a biochemistry hallmark. Although varying degrees of improvement in response to UDCA therapy were observed, 41.1% of PFIC3 patients exhibited unfavorable prognosis. ABCB4 genotypes of biallelic null variants were associated with severer PFIC3 phenotypes. Moreover, the 14 novel variants in this study expanded the ABCB4 mutation spectrum, and provided novel molecular biomarkers for diagnosis of PFIC3 patients.

Progressive Familial Intrahepatic Cholestasis Type 3 Homozygous Pathogenic Variant c.2906G>A in the ATP Binding Cassette Subfamily B Member 4 (ABCB4) Gene: A Case Report of an Unusual Presentation

Progressive familial intrahepatic cholestasis (PFIC) describes a heterogeneous group of autosomal-recessive childhood liver disorders in which cholestasis of hepatocellular origin frequently manifests during infancy or the first year of life and progresses to liver failure. We report a case of a five-year-old boy with homozygous pathogenic variant c.2906G>A in the ATP binding cassette subfamily B member 4 (ABCB4) gene presented with hepatosplenomegaly and cytopenia without a history of jaundice or itching; he had a history of Epstein-Barr virus infection and family history of liver disease. The patient was started on ursodeoxycholic acid and fat-soluble vitamins and referred to a liver transplant center.

Long-Term Results of Pediatric Liver Transplantation for Progressive Familial Intrahepatic Cholestasis

We analyzed the long-term survival rate and development of progressive familial intrahepatic cholestasis (PFIC) patients after liver transplantation (LT). From October 2007 to May 2019, 41 patients were diagnosed as PFIC (type I-III) and received LT in Ren Ji Hospital due to end-stage liver diseases. The median age at LT was 2.93 years, with 75.6% of patients receiving living donor liver transplantation (LDLT). The 5- and 10-year patient survival rates after LT were 92.7% and 92.7%, respectively, and no difference was found among the three subtypes of PFIC. Two PFIC type II patients received re-transplantation due to vascular complications. Liver function and bile acid metabolism returned to normal levels in all living recipients. Catch-up growth was recorded as the height and weight Z scores increased from −2.53 and −1.54 to −0.55 and −0.27 with a median follow-up time of 5.55 years. Improved psychomotor ability and age-appropriate study ability was also observed. A total of 72.4% of school-aged recipients exhibited average academic performance. Diarrhea was reported in all PFIC type I recipients but resolved after resin absorptive treatment. However, allograft steatosis occurred in one PFIC type I patient and exhibited a “remission–relapse circle” under the treatment of cholestyramine. In conclusion, LT is an effective treatment for end-stage PFIC patients with encouraging long-term survival rate and development. However, allograft steatosis should be closely monitored in PFIC type I patients even if diarrhea has been well treated.

Pediatric acute viral hepatitis with atypical variants: Clinical dilemmas and natural history

Classical acute viral hepatitis (AVH) has an uncomplicated outcome. Acute liver failure has a grave prognosis. Atypical manifestations of AVH are a group of disorders that causes significant morbidity and dilemmas in children. These include prolonged cholestasis, relapsing hepatitis, ascitic form of AVH, late-onset hepatic failure (LOHF), intravascular hemolysis, and provoking an autoimmune trigger leading to autoimmune hepatitis. These entities cause significant liver dysfunction or worsening and are often difficult to differentiate from chronic liver disease (CLD). Ascitic form of AVH, LOHF, decompensated CLD and acute-on-chronic liver failure have significant overlapping features that need to be carefully dissected out. In many cases, only on long-term follow-up, these clinical entities can be separately identified. Intravascular hemolysis is usually caused by associated glucose-6-phosphate dehydrogenase deficiency. Rarely CLD such as Wilson disease and autoimmune hepatitis can also present with hemolysis in the initial presentation, which can mimic AVH with hemolysis. Identifying deviations from typical manifestations aid in avoiding unnecessary investigations, allowing focused therapy and alleviating anxiety.

Gene Therapy for Acquired and Genetic Cholestasis

Cholestatic diseases can be caused by the dysfunction of transporters involved in hepatobiliary circulation. Although pharmacological treatments constitute the current standard of care for these diseases, none are curative, with liver transplantation being the only long-term solution for severe cholestasis, albeit with many disadvantages. Liver-directed gene therapy has shown promising results in clinical trials for genetic diseases, and it could constitute a potential new therapeutic approach for cholestatic diseases. Many preclinical gene therapy studies have shown positive results in animal models of both acquired and genetic cholestasis. The delivery of genes that reduce apoptosis or fibrosis or improve bile flow has shown therapeutic effects in rodents in which cholestasis was induced by drugs or bile duct ligation. Most studies targeting inherited cholestasis, such as progressive familial intrahepatic cholestasis (PFIC), have focused on supplementing a correct version of a mutated gene to the liver using viral or non-viral vectors in order to achieve expression of the therapeutic protein. These strategies have generated promising results in treating PFIC3 in mouse models of the disease. However, important challenges remain in translating this therapy to the clinic, as well as in developing gene therapy strategies for other types of acquired and genetic cholestasis.