Systemic cytokine profiles in biliary atresia

Increased serum GM-CSF at diagnosis of biliary atresia is associated with improved biliary drainage

BACKGROUND

The immune heterogeneity of biliary atresia (BA) presents a challenge for development of prognostic biomarkers. This study aimed to identify early immune signatures associated with biliary drainage after Kasai Portoenterostomy (KPE).

METHODS

Serum samples, liver slides, and clinical data were obtained from patients enrolled in the NIDDK-supported Childhood Liver Disease Research Network. Serum cytokines and hepatic immune cell subsets were measured at diagnosis and compared among 3 groups: 38 infants with BA (20 with evidence of bile flow after KPE; 18 without) and 17 non-BA cholestatic infants.

RESULTS

BA participants had lower numbers of lipid associated macrophages (LAM), and increased serum levels of Eotaxin-3, interleukin (IL) 12p70, and IL-8 versus non-BA groups (p < 0.05 for all). Among BA participants, monocyte like macrophages and serum levels of granulocyte-macrophage colony stimulating factor (GM-CSF) were increased in BA participants with good biliary drainage (p = 0.004 and p < 0.001 respectively). Levels of GM-CSF, IL-16, c-reactive protein, TNF-β predicted successful biliary drainage with an area under the receiver operating curve of 0.84 (p < 0.001).

CONCLUSION

These findings suggest that distinct macrophage-associated immune networks at diagnosis may impact biliary drainage after KPE. Identification of early prognostic immune-modulatory markers has potential to improve patient stratification for medical and surgical therapies.

IMPACT STATEMENT

We identify serum cytokines, particularly GM-CSF, that are associated with future biliary drainage in patients with biliary atresia. Characterization of macrophage-associated immune networks provides novel insight into early disease mechanism that may impact patient outcomes. Early prognostic biomarkers markers in biliary atresia can help in patient stratification for medical and surgical therapies.

Interleukin 8-CXCR2-mediated neutrophil extracellular trap formation in biliary atresia associated with neutrophil extracellular trap-induced stellate cell activation

BACKGROUND AND AIMS

Biliary atresia (BA) entails an inflammatory sclerosing lesion of the biliary tree, with prominent fibrosis in infancy. Previous studies revealed that neutrophil-activating IL-8 and neutrophil extracellular traps (NETs) positively correlated with bilirubin and the risk of liver transplant. The aims of this study were to determine the mechanism of NET formation (NETosis) in BA and whether NETs induce stellate cell activation.

APPROACH AND RESULTS

BA and other liver disease control plasma and tissue were obtained at diagnosis and transplant. Elastase, NETs, and IL-8 were quantified by ELISA for plasma and by immunohistochemistry for liver tissue. FACS analysis of neutrophils co-cultured with BA or control plasma measured BA-specific NETosis. Stellate cell activation from co-culture studies of stellate cells with NETs was measured by real-time quantitative PCR, ELISA, and FACS. Liver neutrophils and NETs, and plasma elastase, NETs, and IL-8, were significantly increased in BA at diagnosis and transplant. Normal neutrophils co-cultured with BA plasma had increased NETosis and activation of CXCR2, an IL-8 receptor; CXCR2 inhibition decreased NET production. Immunohistochemistry identified increased NET expression of profibrogenic tissue factor and IL-17. NETs co-cultured with stellate cells resulted in stellate cell activation based on increased ACTA2 and COL1A1 mRNA, collagen protein, and cell surface expression of actin, collagen1A, and platelet-derived growth factor receptor-beta.

CONCLUSIONS

Patients with BA have persistent IL-8-CXCR2-mediated NETosis that correlates with biomarkers of injury and fibrosis, and NETs induce stellate cell activation, suggesting a role for NETs in the immunopathogenesis of disease. Future investigations should focus on therapeutic agents that inhibit NETs in BA.

Perinatal liver inflammation is associated with persistent elevation of CXCL10 and its canonical receptor CXCR3 on common myeloid progenitors

Biliary atresia (BA) is a leading cause of liver failure in infants. Despite effective surgical drainage, patients with BA exhibit attenuated immune responses to childhood vaccines, suggesting there are long-lasting alterations to immune function. The perinatal liver is home to hematopoietic stem and progenitor cells (HSPCs) and serves as the epicenter for rapidly progressive and significantly morbid inflammatory diseases like BA. We have previously established the role of neonatal myeloid progenitors in the pathogenesis of perinatal liver inflammation (PLI) and hypothesize that PLI leads to long-term changes to HSPCs in mice that recovered from PLI. To test this hypothesis, we compared the changes that occur to HSPCs and mature myeloid populations in the bone marrow of adult mice during homeostasis and during PLI. Our results demonstrate that HSPCs from animals that recover from PLI ("PLI-recovered") undergo long-term expansion with a reduced proliferative capacity. Notably, PLI leads to persistent activation of common myeloid progenitors through the involvement of CXCL10 and its canonical receptor, CXCR3. Our data suggests that the CXCR3-CXCL10 axis may mediate the changes in HSPCs that lead to altered immune function observed in BA, providing support for a targetable pathway to mitigate the detrimental long-term immune effects observed in patients with BA.

Neutrophil-to-lymphocyte ratio may predict complications and patency in bile duct injury repair

BACKGROUND

Bile duct injury (BDI) repair surgery is usually associated with morbidity/mortality. The neutrophil-to-lymphocyte ratio (NLR) easily assesses a patient's inflammatory status. The study aims to determine the possible relationship between preoperative NLR (pNLR) with postoperative outcomes in BDI repair surgery.

METHODS

Approved Ethics/Research Committee retrospective study, in patients who had a Bismuth-Strasberg type E BDI repair (2008-2023). Data registered was: morbidity, mortality, and long-term outcomes (primary patency and loss of primary patency) (Kaplan-Meier). Group comparison (U Mann-Whitney), receiver operator characteristic (ROC): area under curve [AUC]; cut-off value, and Youden index [J], and logistic regression analysis were used for pNLR evaluation.

RESULTS

Seventy-three patients were studied. Mean age was 44.4 years. E2 was the commonest BDI (38.4%). Perioperative morbidity/mortality was 31.5% and 1.4%. Primary patency was 95.9%. 8.2% have lost primary patency (3-year actuarial patency: 85.3%). Median pNLR was higher in patients who had any complication (4.84 vs. 2.89 p = 0.015), biliary complications (5.29 vs. 2.86 p = 0.01), and patients with loss of primary patency (5.22 vs. 3.1 p = 0.08). AUC's, cut-off values and (J) were: any complication (0.678, pNLR = 4.3, J = 0.38, p = 0.007), serious complication (0.667, pNLR = 4.3, J = 0.34, p = 0.04), biliary complications (0.712, pNLR = 3.64, J = 0.46, p = 0.001), and loss of primary patency (0.716, pNLR = 3.24, J = 0.52, p = 0.008). Logistic regression was significant in any complication (Exp [B]: 0.1, p = 0.002), serious complications (Exp [B]: 0.2, p = 0.03), and biliary complications (Exp [B]: 8.1, p = 0.003).

CONCLUSIONS

pNLR is associated with complications in BDI repair with moderate to acceptable predictive capacity. pNLR could potentially predict patency of a BDI repair.

In Utero Extrahepatic Bile Duct Damage and Repair: Implications for Biliary Atresia

Biliary atresia (BA) is a cholangiopathy affecting the extrahepatic bile duct (EHBD) of newborns. The etiology and pathophysiology of BA are not fully understood; however, multiple causes of damage and obstruction of the neonatal EHBD have been identified. Initial damage to the EHBD likely occurs before birth. We discuss how different developmental stages in utero and birth itself could influence the susceptibility of the fetal EHBD to damage and a damaging wound-healing response. We propose that a damage-repair response of the fetal and neonatal EHBD involving redox stress and a program of fetal wound healing could-regardless of the cause of the initial damage-lead to either obstruction and BA or repair of the duct and recovery. This overarching concept should guide future research targeted toward identification of factors that contribute to recovery as opposed to progression of injury and fibrosis. Viewing BA through the lens of an in utero damage-repair response could open up new avenues for research and suggests exciting new therapeutic targets.

Exploring causality with biliary atresia at different levels: two-sample Mendelian randomization study

Background

In recent years, Mendelian randomization (MR) has been widely used to infer causality of related disease risk exposures. However, this strategy has not been applied to biliary atresia (BA).

Methods

Genome-wide association studies (GWAS) data of 41 inflammatory cytokines, 731 immune cell traits, and 1400 metabolites were obtained from public databases as exposure factors. The outcome information was obtained from a GWAS meta-analysis of 499 children with BA and 1928 normal controls. Inverse variance weighting was the primary causality analysis. Cochran Q-test, MR-Egger intercept, MR pleiotropy residual sum and outlier, and 'leave-one-out' analyses were used for sensitivity analysis. Reverse MR, MR-Steiger, and Linkage Disequilibrium Score were used to exclude the effects of reverse causality, genetic association, and linkage disequilibrium.

Results

MR results showed that a total of seven traits had potential causal relationships with BA, including three inflammatory cytokines: eotaxin (odds ratio (OR)=1.45, 95% confidence interval (CI): 1.08 to 1.95, p FDR=0.18), G-CSF (OR=4.21, 95% CI: 1.75 to 10.13, p FDR=0.05) and MCP-1/MCAF (OR=1.53, 95% CI: 1.12 to 2.10, p FDR=0.14); three immune cell traits: CD8dim NKT/T cells ratio (OR=0.59, 95% CI: 0.45 to 0.77, p FDR=0.06), CD8dim NKT counts (OR=0.58, 95% CI: 0.43 to 0.78, p FDR=0.06), CD8dim NKT/lymphocyte ratio (OR=0.63, 95% CI: 0.49 to 0.81, p FDR=0.06); one metabolite: X-12261 levels (OR=2.86, 95% CI: 1.73 to 4.74, p FDR=0.06).

Conclusions

In this study, eotaxin, G-CSF, MCP-1/MCAF, and X-12261 levels were shown to be risk factors for BA. However, CD8dim NKT/T cells ratio, CD8dim NKT counts, and CD8dim NKT/lymphocyte ratio were protective factors for BA. These findings provided a promising genetic basis for the etiology, diagnosis, and treatment of BA.

Progress in Biomarkers Related to Biliary Atresia

Biliary atresia (BA) is a congenital cholestatic disease that can seriously damage children's liver function. It is one of the main reasons for liver transplantation in children. Early diagnosis of BA is crucial to the prognosis of patients, but there is still a lack of reliable non-invasive diagnostic methods. Additionally, as some children are in urgent need of liver transplantation, evaluating the stage of liver fibrosis and postoperative native liver survival in children with BA using a straightforward, efficient, and less traumatic method is a major focus of doctors. In recent years, an increasing number of BA-related biomarkers have been identified and have shown great potential in the following three aspects of clinical practice: diagnosis, evaluation of the stage of liver fibrosis, and prediction of native liver survival. This review focuses on the pathophysiological function and clinical application of three novel BA-related biomarkers, namely MMP-7, FGF-19, and M2BPGi. Furthermore, progress in well-known biomarkers of BA such as gamma-glutamyltransferase, circulating cytokines, and other potential biomarkers is discussed, aiming to provide a reference for clinical practice.

Elevated serum IL-34 is correlated with disease severity in patients with biliary atresia following Kasai portoenterostomy

BACKGROUND

Biliary atresia (BA) is a severe congenital disorder with progressive obstructive cholangiopathy in young children. The inflammatory process has been recognized as one of the pathological mechanisms driving bile duct injury. Since interleukin-34 (IL-34) has been reportedly linked to several pathological liver disorders, including inflammation, the current study aimed to analyze circulating IL-34 and the association of circulating IL-34 with hepatic deterioration and clinical outcomes in post-Kasai BA children.

METHODS

Circulating IL-34 levels were analyzed in 89 post-Kasai BA subjects and 45 healthy individuals using an ELISA. Liver stiffness (hardness) was measured by ultrasound elastography.

RESULTS

Circulating IL-34 was substantially higher in BA children than in control individuals, particularly those with unfavorable outcomes including hepatic dysfunction, jaundice, and portal hypertension. In BA group, circulating IL-34 was positively correlated with liver stiffness (r = 0.515, p < 0.001), AST (r = 0.403, p < 0.001), ALT (r = 0.279, p = 0.008), total bilirubin (r = 0.224, p = 0.03), ALP (r = 0.255, p = 0.016), and serum IL-6 (r = 0.590, p < 0.001) but inversely correlated with albumin (r = -0.417, p < 0.001). Kaplan-Meier survival analysis showed that higher circulating IL-34 levels were significantly associated with reduced survival rates in BA subjects (p = 0.002).

CONCLUSION

Higher circulating IL-34 values were directly associated with hepatic impairment and the BA severity, implicating thatserum IL-34 could be applied as a noninvasive marker for the monitoring of the severity in BA subjects following Kasai portoenterostomy and therapeutic efficacy.

Immune-mediated cholangiopathies in children: the need to better understand the pathophysiology for finding the future possible treatment targets

Cholangiopathies are defined as focal or extensive damage of the bile ducts. According to the pathogenetic mechanism, it may be immune-mediated or due to genetic, infectious, toxic, vascular, and obstructive causes. Their chronic evolution is characterized by inflammation, obstruction of bile flow, cholangiocyte proliferation, and progression toward fibrosis and cirrhosis. Immune-mediated cholangiopathies comprise primary sclerosing cholangitis (PSC), autoimmune cholangitis and IgG4-associated cholangitis in adults and biliary atresia (BA), neonatal sclerosing cholangitis (NSC) in children. The main purpose of this narrative review was to highlight the similarities and differences among immune-mediated cholangiopathies, especially those frequent in children in which cholangiocyte senescence plays a key role (BA, NSC, and PSC). These three entities have many similarities in terms of clinical and histopathological manifestations, and the distinction between them can be hard to achieve. In BA, bile duct destruction occurs due to aggression of the biliary cells due to viral infections or toxins during the intrauterine period or immediately after birth. The consequence is the activation of the immune system leading to severe inflammation and fibrosis of the extrahepatic biliary tract, lumen stenosis, and impairment of the biliary flow. PSC is characterized by inflammation and fibrosis of intra- and extrahepatic bile ducts, leading to secondary biliary cirrhosis. It is a multifactorial disease that occurs because of genetic predisposition [human leukocyte antigen (HLA) and non-HLA haplotypes], autoimmunity (cellular immune response, autoantibodies, association with inflammatory bowel disease), environmental factors (infections or toxic bile), and host factors (intestinal microbiota). NSC seems to be a distinct subgroup of childhood PSC that appears due to the interaction between genetic predisposition (HLA B8 and DR3) and the disruption of the immune system, validated by elevated IgG levels or specific antibodies [antinuclear antibody (ANA), anti-smooth muscle antibody (ASMA)]. Currently, the exact mechanism of immune cholangiopathy is not fully understood, and further data are required to identify individuals at high risk of developing these conditions. A better understanding of the immune mechanisms and pathophysiology of BA, NSC, and PSC will open new perspectives for future treatments and better methods of preventing severe evolution.

Development of liver inflammatory injury in biliary atresia: from basic to clinical research

Biliary atresia (BA) is a severe cholangiopathy in infants. It is characterized by inflammatory fibro-obliteration of the intra- and extrahepatic bile ducts. Although the restoration of bile flow can be successful after Kasai operation, the rapid progression of liver fibrosis can continue, leading to cirrhosis. It is believed that the progression of liver fibrosis in BA is exacerbated by complicated mechanisms other than the consequence of bile duct obstruction. The fibrogenic cascade in BA liver can be divided into three stages, including liver inflammatory injury, myofibroblast activation, and fibrous scar formation. Recent studies have revealed that the activation of an immune response following bile duct injury plays an important role in promoting the inflammatory process, the releasing of inflammatory cytokines, and the development of fibrogenesis in BA liver. In this article, we summarized the evidence regarding liver inflammatory injury and the possible mechanisms that explain the rapid progression of liver fibrosis in BA.