The enigma of primary biliary cirrhosis

Detection of Anti-mitochondrial Antibodies Accompanied by Drug-induced Hepatic Injury due to Atorvastatin

A 44-year-old Japanese woman was admitted to our hospital with fatigue and an altered liver function. She had been receiving atorvastatin treatment for 10 months. Although no jaundice was seen, the patient's serum alkaline phosphatase and γ-glutamyl transpeptidase levels were markedly elevated. Based on the results of a drug-induced lymphocyte-stimulation test, her liver disease was diagnosed as atorvastatin-induced hepatic injury. Subsequently, anti-mitochondrial antibodies (AMAs) were detected in her serum; however, a liver biopsy specimen did not show the characteristic features of primary biliary cholangitis. We herein report the detection of AMAs accompanied by drug-induced hepatic injury caused by atorvastatin.

Altered expression of miR-92a correlates with Th17 cell frequency in patients with primary biliary cirrhosis

MicroRNAs (miRNAs or miRs) are small, non-coding RNA molecules that play significant roles in numerous diseases. However, there is limited information regarding the plasma expression of miRNAs in patients with primary biliary cirrhosis (PBC) as well as the potential role of miRNAs in the development of PBC. miRNA microarray analysis was performed using plasma obtaind from three patients with PBC and three healthy controls. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was performed to confirm the differential expression of miRNAs in the plasma and peripheral blood mononuclear cells (PBMCs) isolated from 20 patients with PBC, 20 patients with chronic hepatitis B (CHB) and 20 healthy controls. These miRNAs in PBMCs and plasma were validated by linear regression analyses. The T cell subset frequency was analyzed by flow cytometry. Correlations between altered miRNA expression and the frequency of the T cell subsets were determined by linear regression analyses. The co-expression of miRNAs and IL-17A was examined using fluorescence in situ hybridization (FISH) and immunohistochemistry. The microarray analysis identified sixteen miRNAs that were differentially expressed. Four miRNAs were validated by RT-qPCR. The expression pattern of miR-572 and miR-92a in the PBMCs correlated with the expression pattern in plasma. We also found that miR-92a expression closely correlated with the frequency of a subset of IL-17-producing T helper cells (Th17), and that miR-92a was co-expressed with IL-17A in patients with PBC. Taken together, these findings revealed that plasma from patients with PBC has a unique miRNA expression profile. Moreover, miR-92a may play an important role in the pathogenesis of PBC by regulating Th17 cell differentiation.

Association between cytotoxic T-lymphocyte antigen 4 gene polymorphisms and primary biliary cirrhosis in Chinese population: data from a multicenter study

BACKGROUND AND AIMS

The cytotoxic T-lymphocyte antigen 4 (CTLA4) gene polymorphisms have been shown to be associated with the risk of primary biliary cirrhosis (PBC). The study aimed to confirm the associations of CTLA4 gene polymorphisms with risk of PBC and patients' quality of life in Chinese population.

METHODS

A total of 312 female PBC patients from Chinese Han population were included as case, and 375 age-matched female healthy volunteers were included as control. Four single nucleotide polymorphisms (SNPs) including rs231775, rs3087243, rs231725, and rs5742909 were genotyped. The differences of genotype and allele distributions between PBC patients and healthy controls were assessed. The relationship between CTLA4 gene polymorphisms and healthy status of PBC patients were then investigated through comparisons of the domain scores of PBC-40 questionnaire between different genotype categories of each single nucleotide polymorphism.

RESULTS

The frequencies of G allele at rs231775 and A allele at rs231725 were both significantly increased in PBC patients when compared with normal controls (P < 0.001, odds ratio = 1.44, 95% confidence interval = 1.24-1.67 for rs231775; P < 0.001, odds ratio = 1.29, 95% confidence interval = 1.12-1.48 for rs231725). Besides, patients carrying A allele of rs3087243 had significantly lower score of fatigue domain than those carrying G allele (2.5 ± 0.8 vs 3.9 ± 1.3, P < 0.001).

CONCLUSIONS

This study revealed that CTLA4 gene polymorphism might be associated with susceptibility of PBC. G allele of rs231775 and A allele of rs231725 were significantly associated with the risk of PBC. In addition, patients carrying A allele of rs3087243 could have significantly better quality of life than those carrying G allele.

Autoimmunity and environment: am I at risk?

The complex interplay between environmental factors and genetic susceptibility plays an essential role in disease pathogenesis. This is especially true for autoimmunity, where clinical reports, genomic and epidemiological studies, as well as animal models have identified several environmental and genetic risk factors associated with autoimmune disease. The complexity of this relationship is demonstrated by the vast array of environmental factors that have now been implicated in the induction, and possibly the maintenance of autoimmune disease. The multitude of environmental factors implicated includes both infectious and non-infectious agents. Here, we review one specific autoimmune disease, primary biliary cirrhosis (PBC), as a model for environmental risk factors acting in concert with genetic susceptibility in the disease pathogenesis. PBC is an ideal model, as both infectious and non-infectious environmental agents have been identified as risk factors, and their study provides clues for unravelling the pathogenesis of the disease.

Th17 and regulatory T lymphocytes in primary biliary cirrhosis and systemic sclerosis as models of autoimmune fibrotic diseases

Fibrotic autoimmune diseases are characterized by an inflammatory process in which fibrogenic cytokines, such as TGFβ and IL6, have a major role. Interestingly, these cytokines are also involved in the generation and function of both an effector T lymphocyte subpopulation, the Th17 cells, and the regulatory T lymphocytes (Treg). These evidences raised the hypothesis that an unbalanced equilibrium induced by the overproduction of the fibrogenic cytokines may have pathogenic relevance in fibrotic autoimmune diseases. On this basis, this review analyzes the available data concerning Th17 and Treg generation and function in two representative fibrotic autoimmune diseases, primary biliary cirrhosis (PBC) and systemic sclerosis (SSc), as models for organ-specific and systemic diseases, respectively. With regard to the Th17 cells, their expansion was found to be a common feature associated with a relative contraction of Th1 immune responses. Concerning to the regulatory T cell compartment, quantitative and qualitative alterations were observed in both diseases. However, while PBC patients showed defects only in the CD8+ Treg subset, SSc patients demonstrated abnormalities regarding to both the CD4+CD25+ and the CD8+ Treg subpopulations. Hence, the CD8+ Treg subset seems to be the most involved in the pathogenic cascade leading to fibrotic disease onset and maintenance. Collectively, the reviewed data support the concept that altered homeostasis between effector and regulatory T cell circuits is present in fibrotic autoimmune diseases and that the major factors responsible for such disequilibrium are Th17 cells in the effector arm and CD8+ Treg in the regulatory arm.

Update on the epidemiology of primary biliary cirrhosis

The epidemiology of primary biliary cirrhosis was described as early as the 1970s, yet decades later the true frequency of this disease and its associated risk factors are still in question. There has been a wealth of data documenting the various incidence and prevalence rates across the world, demonstrating potential risk factors inherent to geographic differences. Studies that follow primary biliary cirrhosis in a set population over time have offered the most reliable picture of disease frequency. Analysis of clustering effects through region and time has offered valuable information on the complexity of the disease development. Improved epidemiologic surveillance of primary biliary cirrhosis around the world will be necessary to provide definitive evidence on the phenomenon of clustering and its associations with proposed risk factors in the literature.

Primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is an idiopathic chronic autoimmune liver disease that primarily affects women. It is believed that the aetiology for PBC is a combination between environmental triggers in genetically vulnerable persons. The diagnosis for PBC is made when two of the three criteria are fulfilled and they are: (1) biochemical evidence of cholestatic liver disease for at least 6 month's duration; (2) anti-mitochondrial antibody (AMA) positivity; and (3) histologic features of PBC on liver biopsy. Ursodeoxycholic acid (UDCA) is the only FDA-approved medical treatment for PBC and should be administered at a recommended dose of 13-15 mg/kg/day. Unfortunately despite adequate dosing of UDCA, approximately one-third of patients does not respond adequately and may require liver transplantation. Future studies are necessary to elucidate the role of environmental exposures and overall genetic impact not only in the development of PBC, but on disease progression and variable clinical response to therapy.

Serum inflammatory cytokines, complement components, and soluble interleukin 2 receptor in primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a chronic cholestatic autoimmune liver disease characterized by selective destruction of the intrahepatic bile ducts and highly specific serum anti-mitochondrial autoantibodies (AMA). Several studies have attempted to determine the cytokine pattern characterizing PBC, yet no definitive data have been gathered. The present study was designed to evaluate pro-inflammatory cytokines (IL-1beta, IL-6, TNFalpha), soluble IL-2 receptor (sIL-2R, e.g. soluble CD25), and complement components (C1q, C3, factor B, properdin) levels in sera from 84 patients with PBC and 41 controls. PBC was characterized by significantly higher levels of all pro-inflammatory cytokines when compared to controls; these included IL-1beta (433.3 +/- 13.2 vs. 316.6 +/- 14.7 pg/ml, P < 0.001), IL-6 (701 +/- 17.4 vs. 158 +/- 22.5 pg/ml, P < 0.001), TNFalpha (3.38 +/- 0.6 pg/ml vs. undetectable, P = 0.001), and sIL-2R (1527.1 +/- 106 vs. 566.4 +/- 28.7 U/ml, P < 0.001). Similarly, all complement components were also significantly higher in PBC compared to control sera. In conclusion, PBC sera manifest higher levels of sIL-2R and complement components and this may reflect a perpetuated immune activation. As expected, we also report that all major pro-inflammatory cytokine levels are enhanced in PBC. Further longitudinal analyses could demonstrate a correlation between these markers and disease stage or inflammatory activity, to predict histological staging, disease activity, and response to treatment.

Hepatic IL-17 responses in human and murine primary biliary cirrhosis

The emergence of new regulatory and pro-inflammatory immune cell subsets and cytokines dictates the need to re-examine the role of these subsets in various diseases involving the immune system. IL-17 has been recently identified as a key cytokine involved in numerous autoimmune processes. However, its role in liver autoimmune diseases remains unclear. Primary biliary cirrhosis (PBC) is characterized histologically by autoreactive CD4 and CD8 T cells surrounding damaged bile ducts. CD4(+) T cells are a major source of IL-17, which compose a distinct T helper subset (Th17). Thus we set out to determine the role of IL-17 in both human and a murine model of PBC in a liver-targeted manner. Our data demonstrate an increase in the frequency of IL-17(+) lymphocytic infiltration in liver tissues from PBC patients and those with other liver dysfunctions as compared to healthy livers. IL-2 receptor alpha knockout mice, a recently identified murine model of human PBC, also demonstrate marked aggregations of IL-17-positive cells within portal tracts and increased frequencies of Th17 cells in the liver compared to the periphery. Interestingly, CD4(+) T cells from livers of normal C57BL/6J mice also secreted higher levels of IL-17 relative to those from spleens, indicating a preferential induction of Th17 cells in liver tissues. Importantly, C57BL/6J cocultures of splenic CD4(+) T cells and liver non-parenchymal cells increased IL-17 production approximately 10-fold compared to T cells alone, suggesting a role of the liver microenvironment in Th17 induction in cases of liver autoimmunity and other liver inflammatory diseases.

Recent advances in the epidemiology of primary biliary cirrhosis

Since initial reports in the mid-1970s provided epidemiology data on primary biliary cirrhosis (PBC), many studies have characterized the variable frequency of this disease in diverse populations worldwide and sought to identify associated risk factors. Recent research confirms earlier work suggesting that the incidence and prevalence of PBC are on the rise, although geographic variation persists. Analysis of familial and geographic clustering supports the hypothesis that development and progression of the disease hinge on a complex interplay between genetic and environmental risk factors. International clinical data systems are needed to advance PBC epidemiologic research. Given this complexity, international clinical data systems are needed to advance PBC epidemiologic research.

Clinical epidemiology of primary biliary cirrhosis: incidence, prevalence, and impact of therapy

Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease of unknown etiology. It is typically characterized by a trio of criteria including cholestatic liver biochemistry tests for at least 6 month's duration, the presence of a positive serum antimitochondrial antibody, and histologic findings from liver biopsy that are compatible or diagnostic with PBC. Although no unifying mechanism of action has been described to explain the pathogenesis of PBC to date, the natural history of this condition is greatly influenced by several known and unknown risk factors. In turn, a number of publications have focused on describing the burden of disease and prognosis in patients with PBC, This review article will summarize the descriptive epidemiology of PBC including new insights on risk factors, prognosis, and the effect of medical therapy in contemporary patients.

Anti-mitochondrial antibodies and primary biliary cirrhosis in TGF-beta receptor II dominant-negative mice

Primary biliary cirrhosis (PBC) is an autoimmune disease of the liver, characterized by lymphocytic infiltrates in portal tracts, selective destruction of biliary epithelial cells, and anti-mitochondrial Abs (AMAs). The elucidation of early events in the induction of tissue inflammation and autoimmunity in PBC has been hampered by the cryptic onset of the disease, the practical limitations in accessing the target tissue, and the lack of a suitable animal model. We demonstrate in this study that a mouse transgenic for directed expression of a dominant-negative form of TGF-beta receptor type II (dnTGFbetaRII), under the direction of the CD4 promoter, mimics several key phenotypic features of human PBC, including spontaneous production of AMAs directed to the same mitochondrial autoantigens, namely PDC-E2, BCOADC-E2, and OGDC-E2. The murine AMAs also inhibit PDC-E2 activity. Moreover, there is lymphocytic liver infiltration with periportal inflammation analogous to the histological profile in human PBC. Additionally, the serum cytokine profile of affected mice mimics data in human PBC. The concomitant presence of these immunopathological features in the transgenic mice suggests that the TGF-betaRII pathway is implicated in the pathogenesis of PBC. Finally, these data point away from initiation of autoimmunity by mechanisms such as molecular mimicry and more toward activation of an intrinsically self-reactive T cell repertoire in which necessary regulatory T cell influences are lacking.