Anatomic variations of the intra-hepatic biliary tree in the Caribbean: A systematic review

BACKGROUND

In the classic descriptions of the human liver, the common hepatic duct forms at the confluence of left and right hepatic ducts. Many authors have documented variations in the intra-hepatic ductal system, but to the best of our knowledge there has been no report on bile duct variations in Caribbean populations.

AIM

To evaluate the variations in bile duct anatomy using magnetic resonance cholangiography (MRC) in unselected patients at a major hepatobiliary referral centre in the Eastern Caribbean. Knowledge of the intra-hepatic biliary anatomy is important to optimize service delivery for any physician treating liver and biliary disorders.

METHODS

This study was carried out at a tertiary referral hospital for hepatobiliary diseases in the Eastern Caribbean. We retrospectively evaluated magnetic resonance cholangiograms in 152 consecutive patients at this facility over a two-year period from April 1, 2017 to March 31, 2019. Two consultant radiologists experienced in MRC interpretation reviewed all scans and described biliary anatomy according to the Huang’s classification. A systematic review of published studies was performed and relevant data were extracted in order to calculate the global prevalence of each biliary variant. The variants in our population were compared to the global population.

RESULTS

There were 152 MRCs evaluated in this study in 86 males and 66 females. There were 109 (71.7%) persons with “classic” biliary anatomy (type A1) and variants were present in 43 (28.3%) persons. There was no statistical relationship between the presence of anatomic variants and gender or ethnicity. We encountered the following variants: 29 (19.1%) type A2, 7 (4.6%) type A3, 6 (3.95%) type A4, 0 type A5 and a single variant (quadrification) that did not fit the classification system. Compared to the global prevalence, our population had a significantly greater occurrence of A1 anatomy (71.7% vs 62.6%; P = 0.0227) and A2 trifurcations (19.1% vs 11.5%; P = 0.0069), but a significantly lower incidence of A3 variants (4.61% vs 11.5%; P = 0.0047).

CONCLUSION

There are significant differences in intra-hepatic biliary anatomy in this unselected Eastern Caribbean population compared to global statistics. Specifically, persons of Caribbean descent have a greater incidence of Huang A2 trifurcations and a lower incidence of Huang A3 variants.

CD4+ CXCR5+ T cells in chronic HCV infection produce less IL-21, yet are efficient at supporting B cell responses

BACKGROUND & AIMS

During chronic HCV infection, T cell dependent virus-specific antibodies are produced. However, the role of B-T cell interaction in chronic HCV is largely unknown. CD4(+)CXCR5(+) T follicular helper (TFH)-cells activate B cells and are important for clearance of various chronic viral infections. We investigated the function of TFH cells and B cells in liver and in peripheral blood of chronic HCV patients.

METHODS

T cells from chronic HCV patients and healthy individuals were analysed for expression of CXCR5, PD-1, ICOS, and IL-21 and IFN-γ production by flow cytometry. CD19(+) B cell subpopulations were identified on the basis of CD27 and IgD expression. In order to assess the frequency and function of T cells and B cells in liver follicles, immunohistochemistry was performed for CD3, CXCR5, Bcl6, IL-21, CD20, IgD, IgM, and IgG.

RESULTS

The frequency of IL-21-producing CXCR5(+)CD4(+) T cells in blood was lower in HCV patients compared to healthy individuals (p=0.002), which was reflected by lower serum IL-21 levels (p<0.001). Nonetheless, CXCR5(+)CD4(+) T cells from HCV patients and healthy individuals were equally capable to stimulate CD19(+)CD27(+) memory B cells into IgG and IgM-producing plasmablasts. Importantly, human intrahepatic TFH cells and their related function were identified by immunohistochemistry on liver biopsies for CD3, Bcl6, and CD20 within portal areas and follicles.

CONCLUSIONS

The specific localization of TFH cells and IgG and IgD/IgM-producing B cells suggests a functional B-T cell environment in liver follicles during HCV infection. The decreased frequency of IL-21-producing CXCR5(+)CD4(+) T cells and lower serum IL-21 levels in chronic HCV patients did not lead to an altered TFH-B cell interaction.

Comparable constitutive expression and activity of cytochrome P450 between the lobes of the porcine liver

Due to limited availability of human liver tissue for the study of cytochrome P450 (CYP450), porcine liver tissue has been suggested as an alternative source to prepare microsomes and hepatocytes. The porcine liver is made by four different lobes. The present study investigated the expression and activity of specific CYP450 isoforms in the four lobes, with the purpose to examine if one lobe of the porcine liver resembles the human more than others. Samples from the four major lobes were taken from female pigs and mRNA expression and activity of CYP1A, 2A, 2C, 2D, 2E and 3A determined. The results showed no differences in specific mRNA expression and activity of any of the investigated CYP450 isoforms. In conclusion, the study shows that all parts of the porcine liver are equally useful as model tissue.