Primary biliary cirrhosis: a multi-faced interactive disease involving genetics, environment and the immune response

Conventional type 1 dendritic cells are essential for the development of primary biliary cholangitis

BACKGROUND & AIMS

Primary biliary cholangitis (PBC) is a progressive-cholestatic autoimmune liver disease. Dendritic cells (DC) are professional antigen-presenting cells and their prominent presence around damaged bile ducts of PBC patients are documented. cDC1 is a rare subset of DC known for its cross-presentation abilities and interleukin 12 production. Our aim was to assess the role of cDC1 in the pathogenesis of PBC.

METHODS

We utilized an inducible murine model of PBC and took advantage of the DC reporter mice Zbtb46gfp and the Batf3-/- mice that specifically lack the cDC1 subset. cDC1 cells were sorted from blood of PBC patients and healthy individuals and subjected to Bulk-MARS-seq transcriptome analysis.

RESULTS

Histopathology assessment demonstrated peri-portal inflammation in wild type (WT) mice, whereas only minor abnormalities were observed in Batf3-/- mice. Flow cytometry analysis revealed a two-fold reduction in hepatic CD8/CD4 T cells ratio in Batf3-/- mice, suggesting reduced intrahepatic CD8 T cells expansion. Histological evidence of portal fibrosis was detected only in the WT but not in Batf3-/- mice. This finding was supported by decreased expression levels of pro-fibrotic genes in the livers of Batf3-/- mice. Transcriptome analysis of human cDC1, revealed 78 differentially expressed genes between PBC patients and controls. Genes related to antigen presentation, TNF and IFN signalling and mitochondrial dysfunction were significantly increased in cDC1 isolated from PBC patients.

CONCLUSION

Our data illustrated the contribution the cDC1 subset in the pathogenesis of PBC and provides a novel direction for immune based cell-specific targeted therapeutic approach in PBC.

Microbiomes in pancreatic cancer can be an accomplice or a weapon

Recently, several investigations have linked the microbiome to pancreatic cancer progression. It is critical to reveal the role of different microbiomes in the occurrence, development, and treatment of pancreatic cancer. The current review summarizes the various microbiota types in pancreatic cancer while updating and supplementing the mechanisms of the representative gut, pancreatic, and oral microbiota, and their metabolites during its pathogenesis and therapeutic intervention. Several novel strategies have been introduced based on the tumor-associated microbiome to optimize the early diagnosis and prognosis of pancreatic cancer. The pros and cons involving different microbiomes in treating pancreatic cancer are discussed. The microbiome-related clinical trials for pancreatic cancer theranostics are outlined. This convergence of cutting-edge knowledge will provide feasible ideas for developing innovative therapies against pancreatic cancer.

A high bile acid environment promotes apoptosis and inhibits migration in pancreatic cancer

Bile acids, the main organic solutes in bile, have been established to play an important role at physiological concentrations in gastrointestinal metabolism. However, under pathological conditions, such as cholestatic disease, cholestasis can damage hepatocytes/biliary epithelial cells leading to apoptosis or necrosis. Clinically, pancreatic head cancer usually presents with obstructive jaundice and increased serum bile acid levels, suggesting that pancreatic cancer is intricately correlated with a high bile acid environment in the human body. An increasing body of evidence suggests that bile acids are toxic to normal human and colon cancer cells. Nonetheless, the effect of bile acids on the occurrence and development of pancreatic cancer remains a matter of debate. In the present study, to explore the direct effects of high serum concentrations of bile acids on pancreatic cancer and the possible related mechanisms, human pancreatic cancer (PANC-1) cells were subject to different concentrations of bile acid mixtures to assess cell viability and the migration and invasion ability. Besides, we found that a high bile acid environment could inhibit the proliferation and migration of pancreatic cancer cells through ROS(Reactive oxygen species) induction and the EMT(epithelial-mesenchymal transition) pathway, thereby promoting the apoptosis of pancreatic cancer cells.Abbreviations BAs: Bile Acids; EMT: epithelial-mesenchymal transition; FBS: fatal bovine serum;CCK-8: Cell-Counting-Kit-8; ROS: reactive oxygen species; CA: cholic acid; CDCA: chenodeoxycholic acid; GCDCA: Glycochenodeoxycholic acid; PVDF: Poly vinylidene fluoride.

The Critical Role of Chemokine (C-C Motif) Receptor 2-Positive Monocytes in Autoimmune Cholangitis

The therapy of primary biliary cholangitis (PBC) has lagged behind other autoimmune diseases despite significant improvements in our understanding of both immunological and molecular events that lead to loss of tolerance to the E2 component of pyruvate dehydrogenase, the immunodominant autoepitope of PBC. It is well known that Ly6C^hi monocytes are innate immune cells infiltrating inflammatory sites that are dependent on the expression of C–C motif chemokine receptor 2 (CCR2) for emigration from bone marrow. Importantly, humans with PBC have a circulating monocyte pro-inflammatory phenotype with macrophage accumulation in portal tracts. We have taken advantage of an inducible chemical xenobiotic model of PBC and recapitulated the massive infiltration of monocytes to portal areas. To determine the clinical significance, we immunized both CCR2-deficient mice and controls with 2OA-BSA and noted that CCR2 deficiency is protective for the development of autoimmune cholangitis. Importantly, because of the therapeutic potential, we focused on inhibiting monocyte infiltration through the use of cenicriviroc (CVC), a dual chemokine receptor CCR2/CCR5 antagonist shown to be safe in human trials. Importantly, treatment with CVC resulted in amelioration of all aspects of disease severity including serum total bile acids, histological severity score, and fibrosis stage. In conclusion, our results indicate a major role for Ly6C^hi monocytes and for CCR2 in PBC pathogenesis and suggest that inhibition of this axis by CVC should be explored in humans through the use of clinical trials.

A contemporary perspective on the molecular characteristics of mitochondrial autoantigens and diagnosis in primary biliary cholangitis

Primary biliary cholangitis (PBC) is an autoimmune hepatobiliary disease characterized by immune mediated destruction of the intrahepatic small bile ducts and the presence of antimitochondrial antibodies (AMAs). The mitochondrial autoantigens have been identified as the E2 subunits of the 2-oxo-acid dehydrogenase complex, including the E2 subunits of pyruvate dehydrogenase, branched-chain 2-oxo acid dehydrogenase complex, oxoglutarate dehydrogenase complex, E3 binding protein and PDC E1 alpha subunit. The AMA epitope is mapped within the E2 lipoic acid binding domain, which is particularly important for oxidative phosphorylation. In addition, lipoic acid, which serves as a swinging arm to capture electrons, is particularly susceptible to an electrophilic attack and may provide clues to the etiology of PBC. This review emphasizes the molecular characteristics of AMAs, including detection, immunochemistry and the putative role in disease. These data have significance not only specifically for PBC, but generically for autoimmunity.

Vitamin D in primary biliary cirrhosis, a plausible marker of advanced disease

Vitamin D immune-modulating effects were extensively studied, and low levels have been linked with autoimmune diseases. The associations of vitamin D with autoimmune diseases of the liver, and particularly primary biliary cirrhosis (PBC), are yet to be defined. Hence, in this study, serum levels of vitamin D were determined in 79 patients with PBC and 70 age- and sex-matched controls by the LIAISON chemiluminescent immunoassays (DiaSorin-Italy). Clinical and serological parameters of patients were analyzed with respect to vitamin D status. Mean levels of vitamin D were significantly lower among patients with PBC compared with controls (16.8 ± 9 vs. 22.1 ± 9 ng/ml; p = 0.029), and vitamin D deficiency (≤10 ng/ml) was documented in 33% of patients with PBC versus 7% of controls (p < 0.0001). Vitamin D levels inversely correlated with advanced liver damage and the presence of concomitant autoimmune diseases. In contrast, higher levels of vitamin D were observed among patients with PBC treated with ursodeoxycholic acid (UDCA). In conclusion, low vitamin D levels are common among patients with PBC and correlate with advanced disease, lack of UDCA therapy and autoimmune comorbidity. This alludes to the plausible roles of vitamin D as a prognostic marker of PBC severity, and as a potential player in this disease pathogenesis. While further studies are awaited, monitoring vitamin D in patients with PBC and use of supplements may be advisable.

Primary biliary cirrhosis is a generalized autoimmune epithelitis

Primary biliary cirrhosis (PBC) is a chronic progressive autoimmune cholestatic liver disease characterized by highly specific antimitochondrial antibodies (AMAs) and the specific immune-mediated injury of small intrahepatic bile ducts. Unique apoptotic feature of biliary epithelial cells (BECs) may contribute to apotope presentation to the immune system, causing unique tissue damage in PBC. Perpetuation of inflammation may result in senescence of BECs, contributing to irreversible loss of bile duct. In addition to the classic liver manifestations, focal inflammation and tissue damage are also seen in salivary glands and urinary tract in a significant proportion of PBC patients. These findings provide potent support to the idea that molecular mimicry may be involved in the breakdown of autoimmune tolerance and mucosal immunity may lead to a systematic epithelitis in PBC patients. Thus, PBC is considered a generalized epithelitis in clinical practice.

Predictors of liver failure in primary biliary cirrhosis

BACKGROUND

The disease progression of patients with primary biliary cirrhosis (PBC) varies significantly, and the prognostic markers that identify those patients who will develop liver failure have been scarcely studied from a Chinese cohort. Aims. We aimed to determine the predictive factors of liver failure in patients with PBC.

METHODS

Patients who were first diagnosed as PBC with hepatic compensation between January 2007 and December 2009 were enrolled in this cohort study.

RESULTS

Altogether 398 patients were finally included. Of these patients, 80% were women, 98% had positive antimitochondrial antibodies, and 45% had positive antinuclear antibodies (ANA). To December 2012, a total of 38 patients developed liver failure. According to the outcome, patients who developed liver failure had had higher serum concentration of baseline total bilirubin (TBil) (p = 0.013) and total bile acid (TBA) (p < 0.001), and lower concentrations of baseline total cholesterol (Tch) (p = 0.008), than patients who did not develop liver failure. Additionally, the proportion of ANA positivity was statistically different between the two groups (p = 0.009). In the established model for predicting liver failure in PBC, three variables were finally selected out, including Tch (odds ratio (OR) 0.552, 95% confidence interval (CI) 0.394-0.774, p < 0.001), TBA (OR 1.006, 95% CI 1.002-1.010, p = 0.002), and ANA (+ versus -, OR 5.518, 95% CI 1.155-26.376, p = 0.032).

CONCLUSIONS

ANA, Tch, and TBA are predictors of liver failure in PBC.

High frequency of antiphospholipid antibodies in primary biliary cirrhosis

AIM

To evaluate, retrospectively, the frequency of autoantibodies of antiphospholipid syndrome (APLS) in Tunisian patients with primary biliary cirrhosis (PBC).

PATIENTS AND METHODS

We analyzed 80 PBC sera and 80 sera from blood donors. ELISA was used to determine the frequency of antibodies against cardiolipin (aCL IgG, IgA, and IgM) and beta 2 glycoprotein I (aβ2GPI IgG, IgA, and IgM).

RESULTS

The frequency of antiphospholipid antibodies (aCL and/or aβ2GPI) was significantly higher in PBC patients than in controls (70 vs. 5%, P < 10(-6)). The frequency of aCL antibodies (IgG, IgA or IgM) was significantly higher in PBC patients than in the control group (23.7 vs. 3.7%, P = 0.0005). The frequencies of aCL IgA and aCL IgM in PBC patients' sera were significantly higher than those in the control group (10 vs. 0%, P = 0.003 and 20 vs. 2.5%, P = 0.001, respectively). Two patients of eighty (2.5%) had aCL IgG, aCL IgA and aCL IgM. The frequency of aβ2GPI antibodies (IgG, IgA, or IgM) was significantly higher in PBC patients than in the control group (70 vs. 1.2%, P < 10(-6)). The frequencies of aβ2GPI IgG, aβ2GPI IgA, and aβ2GPI IgM in PBC patients' sera were significantly higher in patients than in the control group (12.5 vs. 0%, P = 0.003; 62.5 vs. 1.2%, P < 10(-6); and 21.2 vs. 0%, P < 10(-4), respectively).

CONCLUSION

Autoantibodies related to APLS (aCL and aβ2GPI) were present in the majority of patients with PBC, reflecting the ability of these antibodies to engage mediators of damage.

Autoantibodies in primary biliary cirrhosis: Recent progress in research on the pathogenetic and clinical significance

Primary biliary cirrhosis (PBC) is a chronic progressive cholestatic liver disease characterized by immune-mediated destruction of the small- and medium-sized intrahepatic bile ducts and the presence of antimitochondrial antibodies (AMA) in the serum. AMA are detected in over 90% of patients with PBC, whereas their prevalence in the general population is extremely low, varying from 0.16% to 1%. Previous studies have shown that the unique characteristics of biliary epithelial cells undergoing apoptosis may result in a highly direct and very specific immune response to mitochondrial autoantigens. Moreover, recent studies have demonstrated that serum from AMA-positive PBC patients is reactive with a number of xenobiotic modified E2 subunits of the pyruvate dehydrogenase complex, which is not observed in the serum of normal individuals. These findings indicate that chemicals originating from the environment may be associated with a breakdown in the tolerance to mitochondrial autoantigens. While it is currently generally accepted that AMA are the most specific serological markers of PBC, more than 60 autoantibodies have been investigated in patients with PBC, and some have previously been considered specific to other autoimmune diseases. This review covers the recent progress in research on the pathogenetic and clinical significance of important autoantibodies in PBC. Determining the pathogenic role of those autoantibodies in PBC remains a priority of basic and clinical research.

Increased activated natural killer T cells in the liver of patients with advanced stage primary biliary cirrhosis

Although growing evidence suggests a major role for T cells in the pathogenesis of primary biliary cirrhosis (PBC), the roles of natural killer (NK) and natural killer T (NKT) cells, which predominate in the liver, in the pathogenesis of PBC remain unclear. We investigated the status of NK and NKT cells in the liver and peripheral blood samples obtained from 11 patients with asymptomatic PBC diagnosed as stage I or II (early PBC) and 7 patients with symptomatic PBC who underwent liver transplantation (advanced PBC) using flow cytometry and immunohistochemical staining. The proportions of NK and NKT cells were significantly decreased in the liver of patients with early PBC compared with normal donors. However, the proportion of CD56+ NKT cells was increased in the liver of patients with advanced PBC. Moreover, the proportion of activated Fas ligand (FasL)-positive NKT cells was significantly increased in the liver of patients with advanced PBC compared with early PBC (P=0.013). We also found increased expression of FasL on lymphocytes infiltrating around the injured bile duct in advanced PBC using immunohistochemical staining. Our results suggest that activated NKT cells may contribute to the biliary epithelial cell death resulting in the progression of PBC.

Mitochondrial haplogroup B4 may be a protective factor to oral lichen planus susceptibility in Chinese

OBJECTIVE

Oral lichen planus (OLP) is a common inflammatory disorder with a higher prevalence among women than men. The pathogenesis of OLP is still unclear, and its heredity is not well characterized. Maternal inheritance of mitochondrial DNA (mtDNA) indicates its importance in human ethnic group classification as well disease susceptibility. So, this study was conducted to find whether mtDNA haplogroup associates with OLP susceptibility in Chinese, and determine the influence of C-stretch structure of mtDNA on OLP susceptibility.

SUBJECTS AND METHODS

We sequenced three hypervariable regions of mtDNA from 242 patients with OLP and 237 healthy controls. The association between mtDNA haplogroups and OLP is tested by chi-square test.

RESULTS

Seventeen kinds of haplogroups were identified, and the frequency of haplogroup B4 was significantly higher in control group than that of the OLP group (P = 0.013, OR=0.429). In female samples, B4 declared even more significance (P = 0.003, OR=0.296). Meanwhile, the haplotypes of C-stretch in mtDNA did not have any significant difference between case-control groups.

CONCLUSIONS

Mitochondrial DNA haplogroup B4 might have a protective effect to OLP, and its protective effect resides predominantly in women. However, the association between C-stretch haplotype and OLP susceptibility still needs more patients for evaluation.