Three unrelated AGS patients and seven children with PFIC were identified and consented for the study. The PFIC patients included four Amish children from the same family with FIC1 disease homozygous for the 923G>T (G308V) mutation in ATP8B1; and three unrelated children with BSEP disease that carried two ABCB11 mutations that would disrupt BSEP synthesis or function. The sequenced mutations included: patient 8 (611+1 G>A/890 A>G (heterozygote), E297G); patient 9 (IVS13del-13^-8/890 A>G (heterozygote), E297G) and patient 10 (1460 G>C (homozygote), R487P). The patients were 7.5 ± 6.4 years old (range 0.4 – 18) at the time of PEBD. The 3 AGS patients were older than the PFIC patients (15.2 ± 3.27 vs. 3.5 ± 2.49 years, p < 0.001), whereas FIC1 disease and BSEP disease patients received PEBD at similar ages (4.25 ± 2.8 vs. 2.53 ± 2.0 years). The follow-up bile samples were collected at 1.35 ± 0.75 years after PEBD (range 0.3–2.5 years).
Clinical criteria and response to PEBD
Patients had elevated serum ALT (97, 40 – 265 IU/L) and bilirubin (4.4, 1.2 – 10.8 mg/dL) concentrations, and marked pruritus before PEBD (Table ). All patients had elevated serum bile acid levels before PEBD (183, 58 – 485 μM/L) with PFIC patients having significantly higher levels (254, 97 – 485 μM/L) than AGS (81, 58 – 97 μM/L) (p = 0.01). Pruritus was slightly greater in AGS than PFIC patients. FIC1 and BSEP disease patients did not differ in regard to serum bilirubin, ALT, bile salts or level of pruritus. There was no difference in the pre-PEBD serum bilirubin level, ALT level, bile salt levels or degree of pruritus between patients who responded and those that did not respond.
Clinical Data OF Patients with AGS, FIC1 and BSEP Disease
Patients had a significant decrease in serum bilirubin (2.8, 0.3 – 6.9 mg/dL) and pruritus score (2, 1 – 4)) after PEBD. The serum bile acids post-PEBD were significantly lower with median 24 (21 – 488) μM/L, with the AGS group being median 24 (21 – 24) μM/L and PFIC group being median 62 (6 – 488) μM/L. In PFIC responders, the bile acid level was significantly lower (6.0, 6.0 – 32 μM/L) than both pre-PEBD levels and the post-PEBD levels of non-responders (119, 62 – 488 μM/L). AGS patients had a significant decrease in pruritus. The serum CDCA/CA ratio post-PEBD was not statistically different among diseases, or among responders versus non-responders.
Overall, three of the 4 FIC1 disease patients had successful clinical responses to PEBD. The oldest at PEBD (patient 7) did not respond; 1.7 years after PEBD he had no improvement in pruritus and had evidence of advancing liver disease with portal hypertension. One of the 3 BSEP disease patients responded to PEBD while the other two (patients 8 and 9) did not respond.
BSEP disease patients overall had the most aggressive histological changes with prominent pseudoacinar changes and portal fibrosis (Table ). Of the PFIC patients with portal fibrosis grade ≥ 3, one of three were responders, while of those with fibrosis grade <3, three of four were responders. Of the 3 BSEP disease patients, the responder had grade 2 portal fibrosis, whereas the two non-responders had grade 2 and 4 fibrosis. Only one AGS patient had undergone biopsy at the time of PEBD (patient 1).
Liver Histology prior to Partial External Biliary Diversion
Lipid composition of bile
The bile from PFIC patients had significantly lower concentrations of all biliary lipids (bile salts, cholesterol and phospholipids) and a lower ratio of chenodeoxycholic acid (CDCA) to cholic acid (CA) than AGS patients (Figure ), (p < 0.05). The ratio of taurine to glycine bile salt conjugates in bile and the hydrophobicity index was not different between PFIC and AGS patients.
Figure 1 Biliary lipid content in AGS and PFIC patients prior to Partial External Biliary Diversion (PEBD). Gallbladder bile was obtained from patients prior to PEBD and analyzed for bile salt, cholesterol and phospholipid content. AGS (n = 3), PFIC (n = 7). Mean (more ...)
Bile from FIC1 disease and BSEP disease patients were not different in regard to total bile salt, cholesterol and phospholipid content. They differed significantly, however, in the percent ursodeoxycholic acid enrichment and hydrophobicity. BSEP disease patients had median 37, range 29 to 60% ursodeoxycholic acid enrichment compared to median 2.29, range 0.9 to 4.2 in FIC1 disease patients (p = 0.05). As a result, the hydrophobicity index of bile was median -0.15, range -0.05 to -0.26 in BSEP disease patients vs. median 0.035, range 0.001 to 0.07 in FIC1 patients (p= 0.02). The pre-PEBD biliary lipid composition of PFIC patients who responded to PEBD was not significantly different from non-responders.
The data regarding the percent change in biliary lipid composition after PEBD are presented in Figure and the individual data in Figure . AGS patients showed no significant change in biliary lipid composition after PEBD. Patients with FIC1 disease showed a 4-fold increase in biliary phospholipid content after PEBD (median 1.3, range 0.3 to 2.6 mM, to median 4.9, range 0.9 to 6.0 mM, p = 0.05), and a trend towards an increased CDCA/CA ratio (median 0.00, range 0.00 to 0.07 to median 0.10, range 0.00 to 0.29, p = 0.10). BSEP patients had no significant increase in biliary lipids and had no detectable biliary CDCA post-PEBD, resulting in a decreased CDCA/CA ratio (median 0.00, 0.00 to 0.13 to median 0.0, range 0.0 to 0.0).
Figure 2 Change in lipid content of bile resulting from Partial External Biliary Diversion (PEBD). Bile was obtained from patients before and after PEBD and analyzed for bile salt, cholesterol and phospholipid content. The data is presented as the percent change (more ...)
Figure 3 Change in lipid content of bile after Partial External Biliary Diversion (PEBD) in Individual Patients. A = AGS, F = FIC1, B = BSEP. Bile was obtained from PFIC (n = 7) patients before and after PEBD who had been independently classified as Responders (more ...)
PFIC responders showed a trend toward increased bile salt concentration and CDCA/CA ratio in bile after PEBD, although these did not reach statistical significance (Figure ), but no increase in cholesterol and phospholipid content. In 2 of 3 PFIC non-responders there was a complete absence of CDCA in bile after 1 year of diversion. AGS patients continued to have higher biliary lipid concentrations after PEBD than PFIC patients, both responders and non-responders.
Long-term outcomes after successful PEBD
Patients 4 and 5 had the best outcomes, with relief of cholestasis and marked reduction in serum bilirubin levels. Patient 6 developed severe pancreatitis associated with multi-organ system failure and death 2 years after PEBD. Patient 7 died shortly after liver transplantation. Patient 8 underwent successful liver transplantation 2.5 years after PEBD for massive ostomy output, and patient 9 developed hepatocellular carcinoma 1.6 years post-PEBD and died (previously reported in reference 19). Thus, only two of this group of PFIC patients survived with PEBD to demonstrate long-term benefit. All three AGS patients have had good long-term outcome.