Maralixibat in progressive familial intrahepatic cholestasis (MARCH-PFIC): a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial.

BACKGROUND: Progressive familial intrahepatic cholestasis (PFIC) is a group of autosomal recessive disorders, the most prevalent being BSEP deficiency, resulting in disrupted bile formation, cholestasis, and pruritus. Building on a previous phase 2 study, we aimed to evaluate the efficacy and safety of maralixibat-an ileal bile acid transporter inhibitor-in participants with all types of PFIC. METHODS: MARCH-PFIC was a multicentre, randomised, double-blind, placebo-controlled, phase 3 study conducted in 29 community and hospital centres across 16 countries in Europe, the Americas, and Asia. We recruited participants aged 1-17 years with PFIC with persistent pruritus (>6 months; average of ≥1·5 on morning Itch-Reported Outcome [Observer; ItchRO(Obs)] during the last 4 weeks of screening) and biochemical abnormalities or pathological evidence of progressive liver disease, or both. We defined three analysis cohorts. The BSEP (or primary) cohort included only those with biallelic, non-truncated BSEP deficiency without low or fluctuating serum bile acids or previous biliary surgery. The all-PFIC cohort combined the BSEP cohort with participants with biallelic FIC1, MDR3, TJP2, or MYO5B deficiencies without previous surgery but regardless of bile acids. The full cohort had no exclusions. Participants were randomly assigned (1:1) to receive oral maralixibat (starting dose 142·5 µg/kg, then escalated to 570 µg/kg) or placebo twice daily for 26 weeks. The primary endpoint was the mean change in average morning ItchRO(Obs) severity score between baseline and weeks 15-26 in the BSEP cohort. The key secondary efficacy endpoint was the mean change in total serum bile acids between baseline and the average of weeks 18, 22, and 26 in the BSEP cohort. Efficacy analyses were done in the intention-to-treat population (all those randomly assigned) and safety analyses were done in all participants who received at least one dose of study drug. This completed trial is registered with ClinicalTrials.gov, NCT03905330, and EudraCT, 2019-001211-22. FINDINGS: Between July 9, 2019, and March 4, 2022, 125 patients were screened, of whom 93 were randomly assigned to maralixibat (n=47; 14 in the BSEP cohort and 33 in the all-PFIC cohort) or placebo (n=46; 17 in the BSEP cohort and 31 in the all-PFIC cohort), received at least one dose of study drug, and were included in the intention-to-treat and safety populations. The median age was 3·0 years (IQR 2·0-7·0) and 51 (55%) of 93 participants were female and 42 (45%) were male. In the BSEP cohort, least-squares mean change from baseline in morning ItchRO(Obs) was -1·7 (95% CI -2·3 to -1·2) with maralixibat versus -0·6 (-1·1 to -0·1) with placebo, with a significant between-group difference of -1·1 (95% CI -1·8 to -0·3; p=0·0063). Least-squares mean change from baseline in total serum bile acids was -176 µmol/L (95% CI -257 to -94) for maralixibat versus 11 µmol/L (-58 to 80) for placebo, also representing a significant difference of -187 µmol/L (95% CI -293 to -80; p=0·0013). The most common adverse event was diarrhoea (27 [57%] of 47 patients on maralixibat vs nine [20%] of 46 patients on placebo; all mild or moderate and mostly transient). There were five (11%) participants with serious treatment-emergent adverse events in the maralixibat group versus three (7%) in the placebo group. No treatment-related deaths occurred. INTERPRETATION: Maralixibat improved pruritus and predictors of native liver survival in PFIC (eg, serum bile acids). Maralixibat represents a non-surgical, pharmacological option to interrupt the enterohepatic circulation and improve the standard of care in patients with PFIC. FUNDING: Mirum Pharmaceuticals.

Association Between MR Elastography Liver Stiffness and Histologic Liver Fibrosis in Children and Young Adults With Autoimmune Liver Disease.

BACKGROUND. Liver fibrosis is an important clinical endpoint of the progression of autoimmune liver disease (AILD); its monitoring would benefit from noninvasive imaging tools. OBJECTIVE. The purpose of this study was to assess the relationship between MR elastography (MRE) liver stiffness measurements and histologic liver fibrosis, as well as to evaluate the performance of MRE and biochemical-based clinical markers for stratifying histologic liver fibrosis severity, in children and young adults with AILD. METHODS. This retrospective study used an existing institutional registry of children and young adults diagnosed with AILD (primary sclerosing cholangitis [PSC], autoimmune sclerosing cholangitis [ASC], or autoimmune hepatitis [AIH]). The registry was searched to identify patients who underwent both a research abdominal 1.5-T MRI examination that included liver MRE (performed for registry enrollment) and a clinically indicated liver biopsy within 6 months of that examination. MRE used a 2D gradient-recalled echo sequence. One analyst measured mean liver shear stiffness (in kilopascals) for each examination. Laboratory markers of liver fibrosis (aspartate aminotransferase-to-platelet ratio index [APRI] and fibrosis-4 [FIB-4] score) were recorded. For investigational purposes, one pathologist, blinded to clinical and MRI data, determined histologic Metavir liver fibrosis stage. The Spearman rank order correlation coefficient was calculated between MRE liver stiffness and Metavir liver fibrosis stage. ROC analysis was used to evaluate diagnostic performance for identifying advanced fibrosis (i.e., differentiating Metavir F0-F1 from F2-F4 fibrosis), and sensitivity and specificity were calculated using the Youden index. RESULTS. The study included 46 patients (median age, 16.6 years [IQR, 13.7-17.8 years]; 20 female patients, 26 male patients); 12 had PSC, 10 had ASC, and 24 had AIH. Median MRE liver stiffness was 2.9 kPa (IQR, 2.2-4.0 kPa). MRE liver stiffness and Meta-vir fibrosis stage showed strong positive correlation (ρ = 0.68). For identifying advanced liver fibrosis, MRE liver stiffness had an AUC of 0.81, with sensitivity of 65.4% and specificity of 90.0%; APRI had an AUC of 0.72, with sensitivity of 64.0% and specificity of 80.0%; and FIB-4 score had an AUC of 0.71, with sensitivity of 60.0% and specificity of 85.0%. CONCLUSION. MRE liver stiffness measurements were associated with histologic liver fibrosis severity. CLINICAL IMPACT. The findings support a role for MRE in noninvasive monitoring of liver stiffness, a surrogate for fibrosis, in children and young adults with AILD. TRIAL REGISTRATION. ClinicalTrials.gov NCT03175471.

Accessible chromatin maps of inflammatory bowel disease intestine nominate cell-type mediators of genetic disease risk.

Inflammatory Bowel Disease ( IBD ) is a chronic and often debilitating autoinflammatory condition, with an increasing incidence in children. Standard-of-care therapies lead to sustained transmural healing and clinical remission in fewer than one-third of patients. For children, TNFα inhibition remains the only FDA-approved biologic therapy, providing an even greater urgency to understanding mechanisms of response. Genome-wide association studies ( GWAS ) have identified 418 independent genetic risk loci contributing to IBD, yet the majority are noncoding and their mechanisms of action are difficult to decipher. If causal, they likely alter transcription factor ( TF ) binding and downstream gene expression in particular cell types and contexts. To bridge this knowledge gap, we built a novel resource: multiome-seq (tandem single-nuclei ( sn )RNA-seq and chromatin accessibility ( snATAC )-seq) of intestinal tissue from pediatric IBD patients, where anti-TNF response was defined by endoscopic healing. From the snATAC-seq data, we generated a first-time atlas of chromatin accessibility (putative regulatory elements) for diverse intestinal cell types in the context of IBD. For cell types/contexts mediating genetic risk, we reasoned that accessible chromatin will co-localize with genetic disease risk loci. We systematically tested for significant co-localization of our chromatin accessibility maps and risk variants for 758 GWAS traits. Globally, genetic risk variants for IBD, autoimmune and inflammatory diseases are enriched in accessible chromatin of immune populations, while other traits (e.g., colorectal cancer, metabolic) are enriched in epithelial and stromal populations. This resource opens new avenues to uncover the complex molecular and cellular mechanisms mediating genetic disease risk.

Protein biomarkers GDF15 and FGF21 to differentiate mitochondrial hepatopathies from other pediatric liver diseases.

BACKGROUND: Mitochondrial hepatopathies (MHs) are primary mitochondrial genetic disorders that can present as childhood liver disease. No recognized biomarkers discriminate MH from other childhood liver diseases. The protein biomarkers growth differentiation factor 15 (GDF15) and fibroblast growth factor 21 (FGF21) differentiate mitochondrial myopathies from other myopathies. We evaluated these biomarkers to determine if they discriminate MH from other liver diseases in children. METHODS: Serum biomarkers were measured in 36 children with MH (17 had a genetic diagnosis); 38 each with biliary atresia, α1-antitrypsin deficiency, and Alagille syndrome; 20 with NASH; and 186 controls. RESULTS: GDF15 levels compared to controls were mildly elevated in patients with α1-antitrypsin deficiency, Alagille syndrome, and biliary atresia-young subgroup, but markedly elevated in MH (p<0.001). FGF21 levels were mildly elevated in NASH and markedly elevated in MH (p<0.001). Both biomarkers were higher in patients with MH with a known genetic cause but were similar in acute and chronic presentations. Both markers had a strong performance to identify MH with a molecular diagnosis with the AUC for GDF15 0.93±0.04 and for FGF21 0.90±0.06. Simultaneous elevation of both markers >98th percentile of controls identified genetically confirmed MH with a sensitivity of 88% and specificity of 96%. In MH, independent predictors of survival without requiring liver transplantation were international normalized ratio and either GDF15 or FGF21 levels, with levels <2000 ng/L predicting survival without liver transplantation (p<0.01). CONCLUSIONS: GDF15 and FGF21 are significantly higher in children with MH compared to other childhood liver diseases and controls and, when combined, were predictive of MH and had prognostic implications.

Longitudinal changes in quantitative magnetic resonance imaging metrics in children and young adults with autoimmune liver disease.

PURPOSE: To assess longitudinal changes in quantitative MRI metrics in pediatric and young adult patients with autoimmune liver disease (AILD). METHODS: This prospective, IRB-approved study included 20 children and young adults (median age = 15 years) with primary sclerosing cholangitis (PSC)/autoimmune sclerosing cholangitis (ASC) and 19 (median age = 17 years) with autoimmune hepatitis (AIH). At a field strength of 1.5-T, T2*-corrected T1 mapping (cT1), 3D fast spin-echo MRCP, and 2D gradient recalled echo MR elastography (MRE) were performed at baseline, one year, and two years. cT1 and quantitative MRCP were processed using LiverMultiScan and MRCP + , respectively (Perspectum Ltd, Oxford, UK). Linear mixed models were used to assess longitudinal changes in quantitative MRI metrics. Spearman rank-order correlation was used to assess relationships between changes in quantitative MRI metrics. RESULTS: Changes in quantitative MRI metrics greater than established repeatability coefficients were measured in six (cT1) and five (MRE) patients with PSC/ASC as well as in six patients (cT1 and MRE) with AIH, although linear mixed models identified no significant changes for the subgroups as a whole. For PSC/ASC, there were positive correlations between change in liver stiffness and changes in bile duct strictures (ρ = 0.68; p = 0.005) and bile duct dilations (ρ = 0.70; p = 0.004) between baseline and Year 2. CONCLUSION: On average, there were no significant changes in quantitative MRI metrics over a two-year period in children and young adults with AILD. However, worsening cholangiopathy was associated with increasing liver stiffness by MRE in patients with PSC/ASC.

Farnesoid X receptor antagonizes macrophage-dependent licensing of effector T lymphocytes and progression of sclerosing cholangitis.

Immune-mediated bile duct epithelial injury and toxicity of retained hydrophobic bile acids drive disease progression in fibrosing cholangiopathies such as biliary atresia or primary sclerosing cholangitis. Emerging therapies include pharmacological agonists to farnesoid X receptor (FXR), the master regulator of hepatic synthesis, excretion, and intestinal reuptake of bile acids. Unraveling the mechanisms of action of pharmacological FXR agonists in the treatment of sclerosing cholangitis (SC), we found that intestinally restricted FXR activation effectively reduced bile acid pool size but did not improve the SC phenotype in MDR2-/- mice. In contrast, systemic FXR activation not only lowered bile acid synthesis but also suppressed proinflammatory cytokine production by liver-infiltrating inflammatory cells and blocked progression of hepatobiliary injury. The hepatoprotective activity was linked to suppressed production of IL1ß and TNFα by hepatic macrophages and inhibition of TH1/TH17 lymphocyte polarization. Deletion of FXR in myeloid cells caused aberrant TH1 and TH17 lymphocyte responses in diethoxycarbonyl-1,4-dihydrocollidine-induced SC and rendered these mice resistant to the anti-inflammatory and liver protective effects of systemic FXR agonist treatment. Pharmacological FXR activation reduced IL1ß and IFNγ production by liver- and blood-derived mononuclear cells from patients with fibrosing cholangiopathies. In conclusion, we demonstrate FXR to control the macrophage-TH1/17 axis, which is critically important for the progression of SC. Hepatic macrophages are cellular targets of systemic FXR agonist therapy for cholestatic liver disease.

Impact of long-term administration of maralixibat on children with cholestasis secondary to Alagille syndrome.

There is growing interest in, but limited data about, intestinal bile acid transport inhibitors as treatment for cholestatic liver disease. The current analyses combine two similar randomized placebo-controlled trials with subsequent extension phases investigating the impact of maralixibat in children with severe cholestasis secondary to Alagille Syndrome (n = 57). The primary outcomes were measures of pruritus (ItchRO[Obs]) and clinician scratch scale (CSS), both increasing in severity from 0 to 4) and quality of life (QoL) (Parent PedsQL and Multidimensional Fatigue Scale module [MFS] scaled 0-100 with increased QoL) at week 48 of the extension phase relative to the baseline of the placebo-controlled trials (week 13). Secondary assessments included other clinical and biochemical parameters assessed in participants at week 72 or end of treatment (after week 48). At week 48, statistically and clinically significant least square mean (95% CI) improvements in pruritus and QoL were observed (ItchRO[Obs] -1.59 [-1.81, -1.36], CSS -1.36 [-1.67, -1.05], PedsQL +10.17 [4.48, 15.86], and multidimension fatigue [MFS] +13.97 [7.85, 20.08]). At week 48, serum bile acids, platelet count, and cholesterol decreased, whereas alanine aminotransferase (ALT) increased and total bilirubin (TB) and albumin were stable. Changes were durable at week 72 and end of treatment. There were no deaths; 2 participants underwent liver transplantation. Study drug was discontinued in 9 participants after treatment-emergent adverse events, 6 of which were events of increased ALT or TB. Conclusion: Maralixibat administration was associated with marked improvement in pruritus and QoL. Interpretation of these findings is complicated by the complex natural history of severe cholestasis in Alagille syndrome.

Associations Between Quantitative MRI Metrics and Clinical Risk Scores in Children and Young Adults With Autoimmune Liver Disease.

BACKGROUND. The Mayo risk score and SCOPE (Sclerosing Cholangitis Outcomes in Pediatrics) index are clinical risk scores for monitoring the progression of primary sclerosing cholangitis (PSC) and predicting clinically important endpoints. OBJECTIVE. The purpose of this study was to evaluate relationships between quantitative MRI measures of liver disease and clinical risk scores in children and young adults with autoimmune liver disease (AILD). METHODS. This prospective study included 58 patients (35 male and 23 female patients; mean age, 15.1 ± 1.1 [SD] years [range, 6-24 years]) with AILD (16 with PSC, 30 with autoimmune hepatitis, and 12 with autoimmune sclerosing cholangitis) who underwent research liver MRI examinations including MR elastography, T2*-corrected T1 (cT1), and quantitative MRCP measurements. Associations between quantitative MRI metrics and clinical risk scores were evaluated using Spearman rank-order correlation coefficients and multivariable regression analyses. RESULTS. The mean Mayo risk score was -1.1 ± 0.9 (SD) (range, -2.9 to 1.1); the mean SCOPE index was 2.7 ± 2.2 (range, 0-9). Mean liver stiffness was 2.8 ± 1.1 kPa, whole-liver mean cT1 was 874.7 ± 77.7 ms, and whole-liver cT1 interquartile range (IQR) was 150.8 ± 55.6 ms. The Mayo risk score was significantly correlated with liver stiffness (ρ = 0.56; p < .001), whole-liver mean cT1 (ρ = 0.31; p = .02), whole-liver cT1 IQR (ρ = 0.58; p < .001), and multiple quantitative MRCP measures (ρ = 0.36-0.45, p < .001). SCOPE index was significantly correlated with liver stiffness (ρ = 0.68; p < .001), whole-liver cT1 IQR (ρ = 0.51; p < .001), and multiple quantitative MRCP measures (ρ = 0.47-0.49; p < .001). Multivariable linear regression analyses identified liver stiffness, whole-liver cT1 IQR, and left hepatic duct maximum diameter as significant independent predictors of the Mayo risk score (adjusted R2 = 0.45), and liver stiffness, whole-liver cT1 IQR, maximum common bile duct (CBD) diameter, and median CBD diameter as significant independent predictors of the SCOPE index (adjusted R2 = 0.69). On logistic regression analysis, greater than low risk by SCOPE index was best predicted by liver stiffness [odds ratio [OR] = 49.6; 95% CI, 3.1-793.6) and maximum CBD diameter (OR = 2.5; 95% CI, 1.3-4.7). CONCLUSION. Increased liver stiffness, increased cT1 IQR, and larger bile duct diameters are independently associated with higher (worse) Mayo risk score and SCOPE index among children and young adults with AILD and may be surrogate markers of clinically meaningful endpoints. CLINICAL IMPACT. Multiparametric MRI of the liver incorporating quantitative metrics may serve as a noninvasive diagnostic and prognostic tool in pediatric AILD. TRIAL REGISTRATION. ClinicalTrials.gov: NCT03175471.

Associations between MRI T1 mapping, liver stiffness, quantitative MRCP, and laboratory biomarkers in children and young adults with autoimmune liver disease.

PURPOSE: Define relationships between quantitative magnetic resonance imaging (MRI) metrics and clinical/laboratory data in a pediatric and young adult cohort with autoimmune liver disease (AILD). MATERIALS AND METHODS: This prospective, cross-sectional study was institutional review board-approved. Patients enrolled in an institutional AILD registry were divided into groups: (1) autoimmune hepatitis (AIH) or (2) primary sclerosing cholangitis (PSC)/autoimmune sclerosing cholangitis (ASC). Participants underwent serum liver biochemistry testing and research MRI examinations, including 3D magnetic resonance cholangiopancreatography (MRCP), magnetic resonance elastography (MRE), and iron-corrected T1 mapping (cT1). MRCP + and LiverMultiScan (Perspectum Ltd., Oxford, UK) were used to post-process 3D MRCP and cT1 data. Multiple linear regression models were used to assess relationships. RESULTS: 58 patients, 35 male, median age 16 years were included; 30 in the AIH group, 28 in the PSC/ASC group. After statistical adjustments for patient age, sex, presence of inflammatory bowel disease (IBD), specific diagnosis (PSC/ASC vs. AIH), and time from diagnosis to MRI examination, left hepatic bile duct maximum diameter was a statistically significant predictor of whole liver mean cT1, cT1 interquartile range (IQR), and MRE liver stiffness (p = 0.01-0.04). Seven laboratory values were significant predictors of whole liver cT1 IQR (p < 0.0001-0.04). Eight laboratory values and right hepatic bile duct median and maximum diameter were significant predictors of liver stiffness (p < 0.0001-0.03). CONCLUSIONS: Bile duct diameters and multiple laboratory biomarkers of liver disease are independent predictors of liver stiffness and cT1 IQR in pediatric patients with AILD.

Association between liver diffusion-weighted imaging apparent diffusion coefficient values and other measures of liver disease in pediatric autoimmune liver disease patients.

BACKGROUND: Multiple quantitative magnetic resonance imaging (MRI) methods have been described to noninvasively detect and characterize liver fibrosis, including diffusion-weighted imaging (DWI). PURPOSE: To evaluate associations between liver MRI DWI apparent diffusion coefficient (ADC) values and clinical factors and other quantitative liver MRI metrics in pediatric patients with autoimmune liver disease (AILD). MATERIALS AND METHODS: Fifty-seven research liver MRI examinations performed from January 2017 to August 2018 for pediatric AILD registry participants were evaluated. Liver DWI ADC values, liver and spleen stiffness (kPa), and iron-corrected T1 (cT1; Perspectum Diagnostics) were measured at four anatomic levels. Participant age, sex, and laboratory data (alanine aminotransferase [ALT], total bilirubin, alkaline phosphatase, gamma-glutamyl transferase [GGT]) were recorded. Spearman's rank-order correlation (rho) and multiple linear regression were used to evaluate the associations between liver ADC values and predictor variables. RESULTS: Mean (SD) participant age was 14.8 (4.0) years, 45.6% (26/57) were girls. Mean liver DWI ADC value was 1.34 (0.14 × 10-3) mm2/s. Liver ADC values showed weak to moderate correlations with liver stiffness (r = - 0.42, p = 0.001), spleen stiffness (r = - 0.34; p = 0.015), whole-liver mean cT1 (r = - 0.39; p = 0.007), ALT (r = - 0.50; p = 0.0001), and GGT (r = - 0.48; p = 0.0004). Multiple linear regression showed liver stiffness (p = 0.0009) and sex (p = 0.023) to be independent predictors of liver ADC values. CONCLUSION: Liver DWI ADC values are significantly associated with liver and spleen stiffnesses, liver cT1, ALT, GGT, and participant sex, with liver stiffness and sex remaining significant at multivariable regression. Liver ADC ultimately may play a role in multi-parametric prediction of chronic liver disease/fibrosis severity.

Serum Matrix Metalloproteinase 7 Is a Diagnostic Biomarker of Biliary Injury and Fibrosis in Pediatric Autoimmune Liver Disease.

In autoimmune liver disease (AILD), including autoimmune hepatitis (AIH), primary sclerosing cholangitis (PSC), and overlap syndrome of AIH and PSC (ASC), the presence of biliary injury portends a worse prognosis. We studied serum matrix metalloproteinase 7 (sMMP7) as a biomarker for pediatric sclerosing cholangitis (SC). We prospectively enrolled 54 children (median age, 16 years) with AILD (AIH, n = 26; ASC, n = 16; and PSC, n = 12) at our center. The sMMP7 concentrations were higher in patients with SC compared to those without cholangiopathy (P < 0.001). An sMMP7 concentration >23.7 ng/mL had a sensitivity and specificity of 79% and 96%, respectively, and outperformed alkaline phosphatase (ALP) and gamma-glutamyltransferase (GGT) in segregating patients with SC. Serum concentrations correlated with liver gene expression levels for MMP7 (r = 0.70; P < 0.001). Using immunofluorescence, MMP7 was localized primarily to the cholangiocytes of patients with SC. In 46 subjects with liver biopsy available for blinded review, elevation in sMMP7 concentrations segregated with the presence of lymphocytic and neutrophilic cholangitis and periductal fibrosis and correlated with Ishak, Ludwig, and Nakanuma scoring systems. Liver stiffness measured by magnetic resonance elastography also correlated with sMMP7 concentrations (r = 0.56; P < 0.01). Using magnetic resonance cholangiopancreatography plus (MRCP+), sMMP7 in 34 patients correlated with the number of biliary dilatations (r = 0.54; P < 0.01) and strictures (r = 0.56; P < 0.01). MMP7 as a marker of biliary injury was validated in an independent cohort of children with ulcerative colitis. Higher sMMP7 concentrations also correlated with a history of SC-related complication. Conclusion: MMP7 is a promising biomarker for pediatric SC that diagnostically outperforms ALP and GGT. sMMP7 may directly reflect biliary injury and fibrosis, the main drivers of disease progression in SC.

Comparison of liver T1 relaxation times without and with iron correction in pediatric autoimmune liver disease.

BACKGROUND: Magnetic resonance imaging (MRI) T1 relaxometry (mapping) has been reported as a quantitative biomarker of liver injury due to inflammation and fibrosis. OBJECTIVE: To assess the relationship between liver MRI T1 relaxometry measurements obtained using a modified Look-Locker inversion recovery (MOLLI) pulse sequence without and with iron (T2*) correction (cT1) in pediatric autoimmune liver disease. MATERIALS AND METHODS: This cross-sectional study was institutional review board-approved, with informed consent obtained. MRI was acquired at 1.5 T in patients participating in an autoimmune liver disease registry. T1 relaxometry was performed using a MOLLI sequence with a 5(3)3-s acquisition strategy. A multi-echo gradient echo sequence was used to measure liver T2*. Non-iron-corrected native T1 (ms), calculated as the mean of four slices through the mid-liver, was measured using T1 parametric maps generated off-line. A proprietary T2* correction (Perspectum Diagnostics, Oxford, UK), blinded to native T1 values, calculated cT1 values. The relationship between native T1 and cT1 measurements was assessed using Spearman rank correlation and Bland-Altman analyses. RESULTS: Forty-eight patients with a mean (standard deviation [SD]) age of 15.2 (4.1) years were included. Mean (SD) liver native T1 was 651.2 (123.9) ms and mean (SD) cT1 was 919.5 (86.8) ms, with excellent positive correlation between values (r=0.91 [95% confidence interval (CI): 0.85-0.95]; P<0.0001). Mean bias between native T1 and cT1 measurements was 268.3 ms (95% limits of agreement: 131.9-404.7 ms). CONCLUSION: There is excellent positive correlation between liver native T1 and cT1 measurements in pediatric patients with autoimmune liver disease. This relationship brings into question the need to perform T1 iron correction in this patient population. T1 and cT1 measurements are not interchangeable, however, due to considerable systematic bias with cT1 values being considerably higher.

Relationship between magnetic resonance imaging spleen T1 relaxation and other radiologic and clinical biomarkers of liver fibrosis in children and young adults with autoimmune liver disease.

BACKGROUND: Little is known about the relationships between MRI splenic T1 relaxation measurements and other radiologic and clinical markers of chronic liver disease, including the presence of radiologic portal hypertension. OBJECTIVE: To evaluate the relationships between MRI splenic T1 relaxation and other radiologic and clinical biomarkers of liver fibrosis, including the presence of radiologic portal hypertension, in children and young adults with autoimmune liver diseases (AILD). MATERIALS AND METHODS: Research MRI examinations performed at 1.5 T from 63 AILD registry participants were identified. Spleen T1 and iron-corrected T1 (cT1) relaxation measurements, liver cT1, liver/spleen stiffness, splenic length percentile for age, and presence of radiologic portal hypertension were recorded, along with demographic and laboratory data. The Mann-Whitney U test was used to compare continuous data between groups; Spearman correlation was used to evaluate associations. Areas-under-the-receiver operating characteristic curve (AuROC) was used to assess diagnostic performance. RESULTS: Mean age was 15.2 ± 4.1 years. Mean splenic T1 and cT1 values for the study population were 1158.0 ± 70.9 ms and 1436.0 ± 68.9 ms, respectively. Splenic T1 and cT1 values positively correlated with APRI and FIBROSIS-4 scores, splenic length percentile, liver cT1 values, and liver and spleen stiffnesses (p-values < 0.05). There was no significant relationship between splenic T1/cT1 and age (p-values > 0.05). Splenic T1 and cT1 values were higher in participants with vs. without radiologic portal hypertension (n = 18) (1213.4 ± 69.6 vs. 1135.4 ± 58.5 ms; p = 0.0001, and 1488.2 ± 64.8 vs. 1415.1 ± 59.1 ms; p = 0.0002). Splenic T1 and cT1 both demonstrated an AuROC of 0.81 for discriminating patients without and with portal hypertension (p-values < 0.0001). CONCLUSION: Splenic T1 relaxation is associated with other radiologic and clinical biomarkers of liver fibrosis, including radiologic portal hypertension, in children and young adults with AILD.

Differentiating pediatric autoimmune liver diseases by quantitative magnetic resonance cholangiopancreatography.

PURPOSE: Autoimmune liver diseases (AILD), including primary sclerosing cholangitis (PSC), autoimmune sclerosing cholangitis (ASC), and autoimmune hepatitis (AIH), have overlapping clinical features but distinct management strategies and outcomes. The purpose of this study was to assess the diagnostic performance of quantitative magnetic resonance cholangiopancreatography (MRCP) parameters for distinguishing PSC/ASC from AIH in children and young adults. MATERIALS AND METHODS: This IRB-approved, cross-sectional study included participants from an institutional AILD registry that underwent baseline serum liver biochemistry testing and 3D fast spin-echo MRCP. The biliary tree was extracted and modeled from MRCP images using novel proprietary software (MRCP+ ™; Perspectum Diagnostics; Oxford, United Kingdom), and quantitative parameters were generated (e.g., biliary tree volume; number and length of bile ducts, strictures, and dilations; bile duct median/maximum diameters). Mann-Whitney U tests were performed to compare laboratory values and MRCP metrics between patient cohorts (clinical diagnosis of PSC/ASC versus AIH). Receiver operating characteristic (ROC) curves and multivariable logistic regression were used to assess diagnostic performance of serum biochemistry values and MRCP parameters for discriminating PSC/ASC from AIH. RESULTS: Thirty percent (14/47) of MRCP exams failed post-processing due to motion artifact. The remaining 33 patients included 20 males and 13 females, with a mean age of 15.1 ± 3.9 years. Eighteen patients were assigned the clinical diagnosis of PSC or ASC and 15 of AIH. All but one quantitative MRCP parameter were significantly different between cohorts (p < 0.05) and predictive of diagnosis (ROC p < 0.05), including numbers of bile duct strictures (area under curve [AUC] = 0.86, p < 0.0001) and dilations (AUC = 0.87, p < 0.0001) and total length of dilated ducts (AUC = 0.89, p < 0.0001). Laboratory values were not significantly different between cohorts (p > 0.05). The best multivariable model for distinguishing PSC/ASC from AIH included total length of dilated ducts (odds ratio [OR], 1.08; 95% CI 1.02-1.14) and maximum left hepatic duct diameter (OR, 1.21; 95% CI 0.57-2.56) [AUC = 0.92]. CONCLUSION: Quantitative MRCP parameters provide good discrimination of PSC/ASC from AIH.

Diagnostic performance of quantitative magnetic resonance imaging biomarkers for predicting portal hypertension in children and young adults with autoimmune liver disease.

BACKGROUND: Primary sclerosing cholangitis, autoimmune hepatitis and autoimmune sclerosing cholangitis are forms of chronic, progressive autoimmune liver disease (AILD) that can affect the pediatric population. OBJECTIVE: To determine whether quantitative MRI- and laboratory-based biomarkers are associated with conventional imaging findings of portal hypertension (radiologic portal hypertension) in children and young adults with AILD. MATERIALS AND METHODS: Forty-four patients with AILD enrolled in an institutional registry underwent a research abdominal MRI examination at 1.5 tesla (T). Five quantitative MRI techniques were performed: liver MR elastography, spleen MR elastography, liver iron-corrected T1 mapping, liver T2 mapping, and liver diffusion-weighted imaging (DWI, quantified as apparent diffusion coefficients). Two anatomical sequences were used to document splenomegaly, varices and ascites. We calculated aspartate aminotransferase (AST)-to-platelet ratio index (APRI) and fibrosis-4 (FIB-4) scores - laboratory-based biomarkers of liver fibrosis. We used receiver operating characteristic (ROC) curve analyses to establish the diagnostic performance of quantitative MRI and laboratory biomarkers for indicating the presence of radiologic portal hypertension. RESULTS: Twenty-three (52%) patients were male; mean age was 15.2±4.0 years. Thirteen (30%) patients had radiologic portal hypertension. Liver and spleen stiffness demonstrated the greatest diagnostic performance for indicating the presence of portal hypertension (area-under-the-ROC-curve [AUROC]=0.98 and 0.96, respectively). The APRI and FIB-4 scores also demonstrated good diagnostic performance (AUROC=0.87 and 0.88, respectively). CONCLUSION: MRI-derived measures of liver and spleen stiffness as well as laboratory-based APRI and FIB-4 scores are highly associated with imaging findings of portal hypertension in children and young adults with AILD and thus might be useful for predicting portal hypertension impending onset and directing personalized patient management.

Interleukin 2 Promotes Hepatic Regulatory T Cell Responses and Protects From Biliary Fibrosis in Murine Sclerosing Cholangitis.

In the multidrug resistance protein 2 (Mdr2)-/- mouse model, low phospholipid bile instigates biliary epithelial injury, sterile inflammation, and fibrosis, thereby recapitulating disease mechanisms implicated in biliary atresia (BA) and primary sclerosing cholangitis. We hypothesize that T lymphocytes contribute to the biliary injury and fibrosis in murine sclerosing cholangitis (SC) and that they are susceptible to suppression by regulatory T cells (Tregs). In juvenile Mdr2-/- mice, intrahepatic CD8+ lymphocytes were expanded, and contraction of intrahepatic Tregs coincided with rising serum alanine transferase and alkaline phosphatase (ALP) levels between days 14-30 of life. Antibody-mediated depletion of intrahepatic CD8+ lymphocytes during that time reduced ALP levels and the expression of osteopontin (Opn), a pro-fibrogenic cytokine. Depletion of intrahepatic Tregs with anti-CD25 antibody between days 7-30 increased intrahepatic CD8+ T cells, Opn expression, and fibrosis. Conversely, expansion of intrahepatic Tregs with interleukin 2/anti-interleukin 2 immune complexes (IL-2c) downregulated hepatic expression of Opn and Tnf, reduced frequency of intrahepatic CD8+ lymphocytes, and diminished biliary injury and fibrosis. Treatment with IL-2c upregulated hepatic Treg expression of CD39, an ectonucleotidase capable of hydrolyzing pro-inflammatory adenosine triphosphate. In vitro, Tregs expressing CD39 suppressed the proliferation of hepatic CD8+ lymphocytes from Mdr2-/- mice more efficiently than those lacking CD39. In infants with BA, infiltration of interlobular bile ducts with CD8+ cells was associated with biliary expression of Opn and its transcription was negatively correlated with mRNA expression of Treg-associated genes. Conclusion: Hepatic CD8+ T lymphocytes drive biliary injury and fibrosis in murine SC. Their proliferation is controlled by hepatic Tregs through the purinergic pathway, which is responsive to IL-2c, suggesting that Treg-directed low-dose Il-2 treatment may be considered as therapy for SC.

The dendritic cell-T helper 17-macrophage axis controls cholangiocyte injury and disease progression in murine and human biliary atresia.

Biliary atresia (BA) is a fibroinflammatory obstruction of the extrahepatic biliary tree in neonates. While intrahepatic bile duct proliferation is universal at diagnosis, bile duct paucity develops later. We hypothesized that polarized T helper lymphocyte responses orchestrate progression of intrahepatic biliary injury in this disease. Interleukin 17A (IL-17A)-green fluorescent protein, cluster of differentiation 11c (CD11c)/diphtheria toxin receptor, and IL-17 receptor A-/- mice were used to examine T-lymphocyte polarization, inflammatory leukocyte recruitment, and biliary injury in rhesus rotavirus-induced BA. Multiparameter flow cytometry and automated image analysis of immunostaining were applied to liver tissue samples from infants with BA. In the mouse model, activated CD4+ lymphocytes started to emerge in the liver on day 8 after viral challenge, while innate immune responses were waning. Plasma IL-17A levels rose concomitantly with hepatic accumulation of T helper 17 lymphocytes and myeloid dendritic cells. Targeted depletion of CD11c+ dendritic cells diminished hepatic IL-17A production and ameliorated intrahepatic bile duct injury. Recombinant IL-17A induced expression of chemokine (C-C motif) ligand 2 in neonatal cholangiocytes in vitro, and blockade of the corresponding chemokine (C-C motif) receptor 2 reduced recruitment of inflammatory macrophages to the liver in vivo. Genetic disruption of IL-17A signaling was associated with down-regulation of hepatic Ccl2/Ccr2 messenger RNA expression, reduced infiltration of the liver with inflammatory Ly6Chi macrophages, and improved survival. In the liver of infants with BA, cholangiocytes were found to express IL-17 receptor A, and the prevalence of IL-17A+ cells was positively correlated with the degree of CD68+ macrophage infiltration at diagnosis. Hepatic CD4+ lymphocytes were chief producers of IL-17A in patients with progressive disease undergoing liver transplantation. CONCLUSION: These findings identify the dendritic cell-T helper 17-macrophage axis as a target for the development of strategies to block progression of intrahepatic bile duct injury in patients with BA. (Hepatology 2017;65:174-188).

Two Case Reports of FGF23-Induced Hypophosphatemia in Childhood Biliary Atresia.

Cholestatic liver disease has long been associated with childhood rickets, secondary to impaired absorption of fat-soluble vitamin D. Elevated serum levels of fibroblast growth factor 23 (FGF23), secondary to genetic defects or tumor-induced osteomalacia, causes hypophosphatemic rickets in childhood. We present 2 infants with end-stage liver disease due to biliary atresia (BA) who developed hypophosphatemia with renal phosphate wasting. Serum FGF23 levels were elevated more than 8 times the upper limit of normal, and the older infant showed radiographic evidence of rickets. Both infants required large supplements of phosphate in addition to calcitriol. Following liver transplantation, FGF23 normalized in both patients and phosphate and calcitriol supplementation were discontinued. Immunohistochemistry revealed ectopic overexpression of FGF23 by hepatocytes in the BA liver. These observations highlight a unique cause of hypophosphatemic rickets in childhood and suggest the need for further investigation into the relationship between BA and other cholestatic disorders, and bone metabolism.