Causal relationship between primary biliary cholangitis and inflammatory bowel disease: a Mendelian randomization study

Background

Several studies indicated that inflammatory bowel disease (IBD) may contribute to increased susceptibility to primary biliary cholangitis (PBC). However, the causal relationship between IBD and PBC remains unclear.

Methods

The genetic variant data of patients with IBD and PBC were obtained from published genome-wide association studies (GWASs). The IBD data were further divided into a discovery dataset and a validation dataset depending on the data source. We conducted a two-sample Mendelian randomization (MR) analysis using the inverse variance weighting (IVW), MR-Egger, weighted median (WM), MR robust adjusted profile score (MR-RAPS), and maximum likelihood (ML) methods, with IVW being the main focus, to verify the causal relationship between IBD and PBC. Additionally, a series of sensitivity analyses were performed to ensure the reliability of the results.

Results

In the discovery cohort, the IVW analysis results (OR = 1.114, P = 0.011) indicated a significant association between IBD and PBC. The MR-RAPS (OR = 1.130, P = 0.007) and ML (OR = 1.115, P = 0.011) analyses yielded results consistent with those of IVW in confirming IBD as a risk factor for PBC. In the validation cohort, consistent findings were observed regarding the causal relationship between IBD and PBC using IVW, MR-RAPS, and ML analyses; all three methods identified IBD as a risk factor for developing PBC. By the IVW analysis, Crohn's disease (CD) emerged as the most prominent subtype of IBD associated with an increased risk of developing PBC in both the discovery cohort (OR = 1.068, P = 0.049) and the validation cohort (OR = 1.082, P = 0.019).

Conclusion

The results of the MR analysis suggest a causal relationship between IBD and PBC, highlighting the necessity for proactive PBC prevention in patients with IBD, particularly those with CD.

HSCs-derived exosomes regulate the levels of inflammatory cytokines in HIBECs through miR-122-5p mediated p38 MAPK signaling pathway

PBC is an autoimmune-mediated liver disease, and intrahepatic biliary epithelial cells (IBECs) are the target cells of early damage. Previous studies found that miRNAs and inflammation is closely related to PBC. In this study, we extracted exosomes from serum and human IBECs supernatant, and RNA-sequence analyzed the expression profiles of miRNAs. Elisa measured the levels of inflammatory cytokines. RT- qPCR and western blot detected the levels of miR-122-5p, p38 and p-p38. The results showed that 263 differentially expressed (DE) miRNAs were identified in serum exosomes of PBC patients. The levels of IL-1β, IL-6, IL-12, IL-17 A, IFN-γ, TNF-α and TGF-β1 in peripheral blood of PBC patients were higher than those of normal controls. According to the validation results and previous literature, exosomal miR-122-5p was finally selected as the study object, and correlated with inflammatory factors. In vitro experiments further found that exosomal miR-122-5p may derive from hepatic stellate cells (HSCs), and can be HIBECs intake, and influence HIBECs inflammatory factor levels though p38 MAPK signaling pathways. This may provide a new strategy for the treatment of PBC.

The Role of miRNA and Long Noncoding RNA in Cholestatic Liver Diseases

Cholestatic liver diseases encompass a range of organic damages, metabolic disorders, and dysfunctions within the hepatobiliary system, arising from various pathogenic causes. These factors contribute to disruptions in bile production, secretion, and excretion. Cholestatic liver diseases can be classified into intrahepatic and extrahepatic cholestasis, according to the location of occurrence. The etiology of cholestatic liver diseases is complex, and includes drugs, poisons, viruses, parasites, bacteria, autoimmune responses, tumors, and genetic metabolism. The pathogenesis of cholelstatic liver disease is not completely clarified; also, there is still a lack of effective therapy methods. It is urgent to clarify its mechanism to find more effective therapeutic targets and drugs. Increasing evidence demonstrates that miRNA and long noncoding RNA are involved in the progression of cholestatic liver diseases. This review provides a comprehensive summary of the research progress on the roles of miRNA and long noncoding RNA in cholestatic liver diseases. The aim is to enhance the understanding of their potential diagnostic, therapeutic, and prognostic value for patients with cholestasis.

Hirsutella sinensis mycelium polysaccharides attenuate the TGF-β1-induced epithelial-mesenchymal transition in human intrahepatic bile duct epithelial cells

Hirsutella sinensis is the anamorph of Ophiocordyceps sinensis, and its mycelia has been used to effectively treat a variety of hepatobiliary diseases in clinical practice. In the present study, we performed a systematic study on the composition and structure of its polysaccharides, and then employed a TGF-β1-induced human intrahepatic bile duct epithelial cell-epithelial-mesenchymal transition (HIBEC-EMT) model to investigate their effects on treating primary biliary cholangitis (PBC) based on hepatic bile duct fibrosis. Four polysaccharide fractions were obtained from H. sinensis mycelia by hot-water extraction, DEAE-cellulose column and gradient ethanol precipitation separation. HSWP-1a was an α-(1,4)-D-glucan; HSWP-1b and HSWP-1d mainly consisted of mannoglucans with a backbone composed of 1,4-linked α-D-Glcp and 1,4,6-linked α-D-Manp residues branched at O-6 of the 1,4-linked α-D-Glcp with a 1-linked α-D-Glcp as a side chain; and HSWP-1c mainly contained galactomannoglucans. These polysaccharide fractions protected HIBECs from a TGF-β1-induced EMT, according to HIBEC morphological changes, cell viability, decreased E-cadherin and ZO-1 expression, and increased vimentin and collagen I expression. Furthermore, the effects of the polysaccharides might be mediated by inhibiting the activation of the TGF-β/Smad signaling pathway, which attenuated hepatic bile duct fibrosis and potential PBC effects.

Targeting Interleukin-17 as a Novel Treatment Option for Fibrotic Diseases

Fibrosis is the end result of persistent inflammatory responses induced by a variety of stimuli, including chronic infections, autoimmune reactions, and tissue injury. Fibrotic diseases affect all vital organs and are characterized by a high rate of morbidity and mortality in the developed world. Until recently, there were no approved antifibrotic therapies. In recent years, high levels of interleukin-17 (IL-17) have been associated with chronic inflammatory diseases with fibrotic complications that culminate in organ failure. In this review, we provide an update on the role of IL-17 in fibrotic diseases, with particular attention to the most recent lines of research in the therapeutic field represented by the epigenetic mechanisms that control IL-17 levels in fibrosis. A better knowledge of the IL-17 signaling pathway implications in fibrosis could design new strategies for therapeutic benefits.

The causal effects of inflammatory bowel disease on primary biliary cholangitis: A bidirectional two-sample Mendelian randomization study

BACKGROUND

Observational studies have indicated that the incidence of primary biliary cholangitis (PBC) is higher in inflammatory bowel disease (IBD) patients than that in healthy people. However, whether the correlation is causal remains unclear.

METHODS

The genetic associations with IBD were obtained from publicly available genome-wide association studies (GWAS) of European ancestry with 31 665 cases and 33 977 controls, consisting of 17 897 Crohn's disease (CD) and 13 768 ulcerative colitis (UC) cases. The genetic associations with PBC were obtained from a European GWAS with 2764 cases and 10 475 controls. A bidirectional two-sample Mendelian randomization (MR) design was implemented to determine the causal relationship between IBD and PBC. In the forward MR, the IBD was treated as the exposure while the PBC was the exposure in the reverse MR. The inverse-variance-weighted (IVW) method was utilized as the main statistic method, and a series of sensitivity analyses were performed to detect heterogeneity and horizontal pleiotropy.

RESULTS

A total of 99 valid instrumental variables (IVs) were selected for IBD and the number of IVs for PBC was 18. The forward MR analysis indicated that genetically predicted IBD (UC and CD) was significantly associated with an increased risk of PBC (IVW OR = 1.343; 95% CI: 1.220-1.466). Similar casual associations were observed in UC (IVW OR = 1.244; 95% CI: 1.057-1.430) and CD (IVW OR = 1.269; 95% CI: 1.159-1.379). Such results were still consistent in multiple MR methods. The reverse MR analysis implicated that genetic susceptibility to PBC might not alter the risk of IBD (IVW OR = 1.070; 95% CI: 0.984-1.164).

CONCLUSION

Our study found that genetically predicted IBD can increase the risk of PBC while not vice versa in the European population, which may enlighten the aetiology of PBC, together with the IBD patient management.

The phenolic compounds tyrosol and hydroxytyrosol counteract liver fibrogenesis via the transcriptional modulation of NADPH oxidases and oxidative stress-related miRNAs

Liver fibrosis is the result of a chronic pathological condition caused by the activation of hepatic stellate cells (HSCs), which induces the excessive deposition of extracellular matrix. Fibrogenesis is sustained by an exaggerated production of reactive oxidative species (ROS) by NADPH oxidases (NOXs), which are overactivated in hepatic inflammation. In this study, we investigated the antifibrotic properties of two phenolic compounds of natural origin, tyrosol (Tyr) and hydroxytyrosol (HTyr), known for their antioxidant and anti-inflammatory effects. We assessed Tyr and HTyr antifibrotic and antioxidant activity both in vitro, by a co-culture of LX2, HepG2 and THP1-derived Mϕ macrophages, set up to simulate the hepatic microenvironment, and in vivo, in a mouse model of liver fibrosis obtained by carbon tetrachloride treatment. We evaluated the mRNA and protein expression of profibrotic and oxidative markers (α-SMA, COL1A1, NOX1/4) by qPCR and/or immunocytochemistry or immunohistochemistry. The expression of selected miRNAs in mouse livers were measured by qPCR. Tyr and HTyr reduces fibrogenesis in vitro and in vivo, by downregulating all fibrotic markers. Notably, they also modulated oxidative stress by restoring the physiological levels of NOX1 and NOX4. In vivo, this effect was accompanied by a transcriptional regulation of inflammatory genes and of 2 miRNAs involved in the control of oxidative stress damage (miR-181-5p and miR-29b-3p). In conclusion, Tyr and HTyr exert antifibrotic and anti-inflammatory effects in preclinical in vitro and in vivo models of liver fibrosis, by modulating hepatic oxidative stress, representing promising candidates for further development.

IL-17 Expression in the Perifollicular Fibrosis in Biopsies From Lichen Planopilaris

BACKGROUND

Lichen planopilaris (LPP) is a primary lymphocytic cicatricial alopecia for which therapy is often ineffective and there is no cure.

OBJECTIVES

Looking for a new targetable molecule in the treatment of LPP, we sought to verify whether IL-17 expression is increased in scalp biopsies from patients with active scalp lesions of LPP.

METHODS

Horizontal sections of hematoxylin and eosin-stained slides from 40 scalp biopsies of active LPP were retrospectively collected and stained with the monoclonal antibody against IL-17 (Abcam, Cambridge, MA; ab79056, dilution 1:100). Twenty biopsies from patients with chronic telogen effluvium served as controls because of their morphological resemblance to the normal scalp. Statistical analysis was performed using IBM SPSS Statistics for Windows (IBM Corporation, Armonk, NY).

RESULTS

The main finding was the positive cytoplasmic expression of IL-17 in the perifollicular fibrosis of the affected follicles in LPP which was statistically significant compared with the controls ( P < 0.0001). The labeled cells were identified as fibroblasts based on their spindle shape and fascicular concentric arrangement in tight perifollicular distribution. Although most of the LPP specimens (n = 35; 87.5%) also revealed cytoplasmic IL-17 expression in the lichenoid inflammatory infiltrate, the results were not statistically significant ( P = 0.1351).

CONCLUSION

Our immunohistochemistry results show that blocking the IL-17 inflammatory pathway may interfere with the progression of the perifollicular fibrosis and inflammation in LPP.

Roles of Non-Coding RNAs in Primary Biliary Cholangitis

Primary biliary cholangitis (PBC) is an autoimmune-mediated chronic cholestatic liver disease, fatigue, and skin itching are the most common clinical symptoms. Its main pathological feature is the progressive damage and destruction of bile duct epithelial cells. Non-coding RNA (NcRNA, mainly including microRNA, long non-coding RNA and circular RNA) plays a role in the pathological and biological processes of various diseases, especially autoimmune diseases. Many validated ncRNAs are expected to be biomarkers for the diagnosis or treatment of PBC. This review will elucidate the pathogenesis of PBC and help to identify potential ncRNA biomarkers for PBC.

Role of Interleukin-17A in the Pathomechanisms of Periodontitis and Related Systemic Chronic Inflammatory Diseases

Periodontitis is a chronic inflammatory and destructive disease caused by periodontal microbial infection and mediated by host immune response. As the main cause of loosening and loss of teeth in adults, it is considered to be one of the most common and serious oral diseases in the world. The co-existence of periodontitis and systemic chronic inflammatory diseases such as rheumatoid arthritis, psoriasis, inflammatory bowel disease, diabetes and so on is very common. It has been found that interleukin-17A (IL-17A) secreted by various innate and adaptive immune cells can activate a series of inflammatory cascade reactions, which mediates the occurrence and development of periodontitis and related systemic chronic inflammatory diseases. In this work, we review the role of IL-17A in the pathomechanisms of periodontitis and related systemic chronic inflammatory diseases, and briefly discuss the therapeutic potential of cytokine targeted agents that modulate the IL-17A signaling. A deep understanding of the possible molecular mechanisms in the relationship between periodontitis and systemic diseases will help dentists and physicians update their clinical diagnosis and treatment ideas.

Th17 cells in the liver: balancing autoimmunity and pathogen defense

In addition to carcinogenesis, T helper 17 (Th17) cells (a subtype of CD4 + T lymphocytes) are involved in the acute, chronic, and cirrhotic phases of liver diseases; however, their role in the development and progression of liver diseases remains unclear. It is difficult to elucidate the role of Th17 cells in liver diseases due to their dichotomous nature, i.e., plasticity in terms of pathogenic or host protective function depending on environmental and time phase factors. Moreover, insufficient depletion of Th17 cells by inhibiting the cytokines and transcription factors involved in their production causes difficulties in analyzing their specific role in vitro and in vivo murine models, partially due to complex interaction. This review summarizes the recent progress in understanding the plasticity and function of hepatic Th17 cells and type 3 cytokines.

The Th17/IL-17 Axis and Kidney Diseases, With Focus on Lupus Nephritis

Systemic lupus erythematosus (SLE) is a disease characterized by dysregulation and hyperreactivity of the immune response at various levels, including hyperactivation of effector cell subtypes, autoantibodies production, immune complex formation, and deposition in tissues. The consequences of hyperreactivity to the self are systemic and local inflammation and tissue damage in multiple organs. Lupus nephritis (LN) is one of the most worrying manifestations of SLE, and most patients have this involvement at some point in the course of the disease. Among the effector cells involved, the Th17, a subtype of T helper cells (CD4+), has shown significant hyperactivation and participates in kidney damage and many other organs. Th17 cells have IL-17A and IL-17F as main cytokines with receptors expressed in most renal cells, being involved in the activation of many proinflammatory and profibrotic pathways. The Th17/IL-17 axis promotes and maintains repetitive tissue damage and maladaptive repair; leading to fibrosis, loss of organ architecture and function. In the podocytes, the Th17/IL-17 axis effects include changes of the cytoskeleton with increased motility, decreased expression of health proteins, increased oxidative stress, and activation of the inflammasome and caspases resulting in podocytes apoptosis. In renal tubular epithelial cells, the Th17/IL-17 axis promotes the activation of profibrotic pathways such as increased TGF-β expression and epithelial-mesenchymal transition (EMT) with consequent increase of extracellular matrix proteins. In addition, the IL-17 promotes a proinflammatory environment by stimulating the synthesis of inflammatory cytokines by intrinsic renal cells and immune cells, and the synthesis of growth factors and chemokines, which together result in granulopoiesis/myelopoiesis, and further recruitment of immune cells to the kidney. The purpose of this work is to present the prognostic and immunopathologic role of the Th17/IL-17 axis in Kidney diseases, with a special focus on LN, including its exploration as a potential immunotherapeutic target in this complication.

MicroRNA-34a Promotes EMT and Liver Fibrosis in Primary Biliary Cholangitis by Regulating TGF-β1/smad Pathway

Background and Aims

Primary biliary cholangitis (PBC) is an autoimmune cholestatic liver disease. We found microRNA-34a (miR-34a), as the downstream gene of p53, was overexpressed in some of fibrogenic diseases. In this study, we sought to explore whether miR-34a plays a role in the fibrosis of PBC.

Methods

The peripheral blood of PBC patients and controls was collected to analyze the level of miR-34a. Human intrahepatic biliary epithelial cells (HIBEC) were cultured. The expression of miR-34a was regulated by miR-34a mimics and inhibitor. The biomarkers of epithelium-mesenchymal transition (EMT), fibrogenesis, inflammation, and transforming growth factor- (TGF-) β1/smad pathway were analyzed.

Results

We found that miR-34a was overexpressed in the peripheral blood in PBC patients. In vitro, overexpressed miR-34a increased the EMT and fibrogenesis activity of HIBEC. Transforming growth factor-beta type 1 receptor (TβR1), TGF-β1, and p-smad2/3 were upregulated by miR-34a. Inflammatory factors such as IL-6 and IL-17 were also upregulated. Finally, we showed that miR-34a promoted EMT and liver fibrosis in PBC by targeting the TGF-β1/smad pathway antagonist transforming growth factor-beta-induced factor homeobox 2 (TGIF2).

Conclusions

Our findings show that miR-34a plays an important role in the EMT and fibrosis of PBC through the TGF-β1/smad pathway by targeting TGIF2. This study suggests that miR-34a may be a new marker of fibrogenesis in PBC. Inhibition of miR-34a may be a promising strategy in treating PBC and improving the prognosis of the disease.

Novel Immune Subsets and Related Cytokines: Emerging Players in the Progression of Liver Fibrosis

Liver fibrosis is a pathological process caused by persistent chronic injury of the liver. Kupffer cells, natural killer (NK) cells, NKT cells, and dendritic cells (DCs), which are in close contact with T and B cells, serve to bridge innate and adaptive immunity in the liver. Meanwhile, an imbalanced inflammatory response constitutes a challenge in liver disease. The dichotomous roles of novel immune cells, including T helper 17 (Th17), regulatory T cells (Tregs), mucosa-associated invariant T cells (MAIT), and innate lymphoid cells (ILCs) in liver fibrosis have gradually been revealed. These cells not only induce damage during liver fibrosis but also promote tissue repair. Hence, immune cells have unique, and often opposing, roles during the various stages of fibrosis. Due to this heterogeneity, the treatment, or reversal of fibrosis through the target of immune cells have attracted much attention. Moreover, activation of hepatic stellate cells (HSCs) constitutes the core of fibrosis. This activation is regulated by various immune mediators, including Th17, Th22, and Th9, MAIT, ILCs, and γδ T cells, as well as their related cytokines. Thus, liver fibrosis results from the complex interaction of these immune mediators, thereby complicating the ability to elucidate the mechanisms of action elicited by each cell type. Future developments in biotechnology will certainly aid in this feat to inform the design of novel therapeutic targets. Therefore, the aim of this review was to summarize the role of specific immune cells in liver fibrosis, as well as biomarkers and treatment methods related to these cells.

Immunological abnormalities in patients with primary biliary cholangitis

Primary biliary cholangitis (PBC), an autoimmune liver disease occurring predominantly in women, is characterized by high titers of serum anti-mitochondrial antibodies (AMAs) and progressive intrahepatic cholestasis. The immune system plays a critical role in PBC pathogenesis and a variety of immune cell subsets have been shown to infiltrate the portal tract areas of patients with PBC. Amongst the participating immune cells, CD4 T cells are important cytokine-producing cells that foster an inflammatory microenvironment. Specifically, these cells orchestrate activation of other immune cells, including autoreactive effector CD8 T cells that cause biliary epithelial cell (BEC) injury and B cells that produce large quantities of AMAs. Meanwhile, other immune cells, including dendritic cells (DCs), natural killer (NK) cells, NKT cells, monocytes, and macrophages are also important in PBC pathogenesis. Activation of these cells initiates and perpetuates bile duct damage in PBC patients, leading to intrahepatic cholestasis, hepatic damage, liver fibrosis, and eventually cirrhosis or even liver failure. Taken together, the body of accumulated clinical and experimental evidence has enhanced our understanding of the immunopathogenesis of PBC and suggests that immunotherapy may be a promising treatment option. Herein, we summarize current knowledge regarding immunological abnormalities of PBC patients, with emphasis on underlying pathogenic mechanisms. The differential immune response which occurs over decades of disease activity suggests that different therapies may be needed at different stages of disease.

Progress in research of mechanism of biliary epithelial cell injury in primary biliary cholangitis

Primary biliary cholangitis (PBC) is an autoimmune liver disease characterized by chronic biliary cholestasis and progressive intrahepatic and small bile duct non- suppurative inflammation with early infiltration of inflammatory cells around biliary epithelial cells (BECs). BECs lining the bile duct express multiple receptors for pathogen-associated molecular patterns and can activate intracellular signaling pathways and participate in immune regulation. The etiology and pathogenesis of PBC are not fully understood yet, but the key step found in its pathogenesis is the targeted destruction of biliary cells. Since bile duct epithelial cells participate in a series of intrahepatic immune regulation processes, bile duct epithelial cell injury is an important mechanism involved in the development of intrahepatic inflammation in PBC. Therefore, understanding the mechanism of BEC injury can help us find some new targets for the treatment of PBC. This article briefly reviews the progress in the research of mechanism of biliary epithelial cell injury in PBC.

IL-17 and IL-17-producing cells and liver diseases, with focus on autoimmune liver diseases

The pro-inflammatory cytokine interleukin(IL)-17 and IL-17-producing cells are important players in the pathogenesis of many autoimmune / inflammatory diseases. More recently, they have been associated with liver diseases. This review first describes the general knowledge on IL-17 and IL-17 producing cells. The second part describes the in vitro and in vivo effects of IL-17 on liver cells and the contribution of IL-17 producing cells to liver diseases. IL-17 induces immune cell infiltration and liver damage driving to hepatic inflammation and fibrosis and contributes to autoimmune liver diseases. The circulating levels of IL-17 and the frequency of IL-17-producing cells are elevated in a variety of acute and chronic liver diseases. The last part focuses on the effects of IL-17 deletion or neutralization in various murine models. Some of these observed beneficial effects suggest that targeting the IL-17 axis could be a new therapeutic strategy to prevent chronicity and progression of various liver diseases.

Toll-like receptor 4 shRNA attenuates lipopolysaccharide-induced epithelial-mesenchymal transition of intrahepatic biliary epithelial cells in rats

BACKGROUND AND AIM

Intrahepatic biliary epithelial cells (IBECs) of the bile duct in liver tissue of patients with hepatolithiasis promoted the development of diseases through epithelial-mesenchymal transition (EMT). This study investigated whether lipopolysaccharide (LPS), a cell-wall constituent of gram-negative bacteria, could induce EMT of IBECs and toll-like receptor 4 (TLR4) had a regulatory role via activating the nuclear factor-κB (NF-κB)/Snail signaling pathway during this process in vivo.

METHODS

TLR4 short hairpin RNA (shRNA) adenovirus or negative control shRNA (NC shRNA) adenovirus (1 × 10⁹ plaque-forming unit (PFU), respectively) was injected into the caudal vein of rats. After 96 h, 1 mg/kg LPS was infused retrogradely into the common bile duct for 48 h per rat. The effects of TLR4 shRNA on LPS-induced EMT were determined by evaluating the histopathological changes in IBECs using hematoxylin and eosin staining and the changes in the levels of EMT markers, TLR4, NF-κB p65, pNF-κB p65, and Snail using real-time polymerase chain reaction and Western blot analysis.

RESULTS

Compared with normal saline treatment, a loss of epithelial cell markers (E-cadherin and cytokeratin 7) and a gain of mesenchymal cell markers (N-cadherin and matrix metalloproteinase 2) were revealed. The levels of TLR4, NF-κB phosphorylation, and Snail significantly increased after LPS treatment, whereas pretreatment with TLR4 shRNA inhibited the LPS-induced EMT by downregulating the NF-κB/Snail signaling pathway.

CONCLUSIONS

LPS induced the EMT of IBECs by activating TLR4. The RNAi-mediated knockdown of TLR4 suppressed EMT occurrence via downregulating the NF-κB/Snail signaling pathway, implicating TLR4 as a new target for human hepatolithiasis.

Deviations in Peripheral Blood Cell Populations are Associated with the Stage of Primary Biliary Cholangitis and Presence of Itching

To evaluate the role of Th17, Treg cells, activated T CD3⁺ and B CD19⁺ lymphocytes in primary biliary cholangitis (PBC) patients. 40 female patients with PBC and 20 healthy donors were enrolled in this study. The percentages and absolute counts of Th17, Treg, activated T CD3⁺, B CD19⁺, NK, NKT-like lymphocytes were measured by flow cytometry. Our research revealed significantly lower frequencies and absolute counts of CD4⁺CD25⁺FOXP3⁺ Treg cells (p < 0.0001), higher percentages and absolute counts of Th17 cells (IL-17A⁺CD3⁺CD4⁺; p < 0.0001 and p = 0.009, respectively), CD3⁻/CD16⁺CD56⁺ NK cells (p < 0.0001 and p = 0.039, respectively), CD3⁺/CD16⁺CD56⁺ NKT-like cells (p < 0.0001 and p = 0.048, respectively). There were also higher percentages and numbers of B CD19⁺ lymphocytes (p = 0.002 and p = 0.001, respectively) and higher percentages and absolute counts of activated B CD19⁺CD25⁺ cells (p = 0.007 and p = 0.002, respectively). Moreover, we observed a statistically significant correlation between the presence of itching and particular peripheral blood subpopulations in PBC patients. Absolute counts of both CD4⁺CD3⁺ cells (p = 0.0119) and CD3⁺CD25⁺ cells (p = 0.0329) were lower in patients with pruritus. A similar dependency was noted in reference to percentages of NKT-like cells (CD3⁺/CD16⁺CD56⁺; p = 0.0359) and (CD3⁺) T lymphocytes (p = 0.0302). Th17 and Treg cells are involved in the course of PBC. There is also the association between the pruritus and peripheral blood subpopulations.

MicroRNA-506 promotes primary biliary cholangitis-like features in cholangiocytes and immune activation

Primary biliary cholangitis (PBC) is a chronic cholestatic liver disease associated with autoimmune phenomena targeting intrahepatic bile duct cells (cholangiocytes). Although its etiopathogenesis remains obscure, development of antimitochondrial autoantibodies against pyruvate dehydrogenase complex E2 is a common feature. MicroRNA (miR) dysregulation occurs in liver and immune cells of PBC patients, but its functional relevance is largely unknown. We previously reported that miR-506 is overexpressed in PBC cholangiocytes and directly targets both Cl- / HCO3- anion exchanger 2 and type III inositol 1,4,5-trisphosphate receptor, leading to cholestasis. Here, the regulation of miR-506 gene expression and its role in cholangiocyte pathophysiology and immune activation was studied. Several proinflammatory cytokines overexpressed in PBC livers (such as interleukin-8 [IL8], IL12, IL17, IL18, and tumor necrosis factor alpha) stimulated miR-506 promoter activity in human cholangiocytes, as revealed by luciferase reporter assays. Experimental overexpression of miR-506 in cholangiocytes dysregulated the cell proteomic profile (by mass spectrometry), affecting proteins involved in different biological processes including mitochondrial metabolism. In cholangiocytes, miR-506 (1) induced dedifferentiation with down-regulation of biliary and epithelial markers together with up-regulation of mesenchymal, proinflammatory, and profibrotic markers; (2) impaired cell proliferation and adhesion; (3) increased oxidative and endoplasmic reticulum stress; (4) caused DNA damage; and (5) sensitized to caspase-3-dependent apoptosis induced by cytotoxic bile acids. These events were also associated with impaired energy metabolism in mitochondria (proton leak and less adenosine triphosphate production) and pyruvate dehydrogenase complex E2 overexpression. Coculture of miR-506 overexpressing cholangiocytes with PBC immunocytes induced activation and proliferation of PBC immunocytes.

CONCLUSION

Different proinflammatory cytokines enhance the expression of miR-506 in biliary epithelial cells; miR-506 induces PBC-like features in cholangiocytes and promotes immune activation, representing a potential therapeutic target for PBC patients. (Hepatology 2018;67:1420-1440).

Immunity and Fibrogenesis: The Role of Th17/IL-17 Axis in HBV and HCV-induced Chronic Hepatitis and Progression to Cirrhosis

Cirrhosis is a common final pathway for most chronic liver diseases; representing an increasing burden worldwide and is associated with increased morbidity and mortality. Current evidence has shown that, after an initial injury, the immune response has a significant participation in the ongoing damage, and progression from chronic viral hepatitis (CVH) to cirrhosis, driving the activation and maintenance of main fibrogenic pathways. Among immune deregulations, those related to the subtype 17 of T helper lymphocytes (Th17)/interleukin-17 (IL-17) axis have been recognized as key immunopathological and prognostic elements in patients with CVH. The Th17/IL-17 axis has been found involved in several points of fibrogenesis chain from the activation of stellate cells, increased expression of profibrotic factors as TGF-β, promotion of the myofibroblastic or epithelial–mesenchymal transition, stimulation of the synthesis of collagen, and induction of imbalance between matrix metalloproteinases and tissue inhibitors of metalloproteinases (TIMPs). It also promotes the recruitment of inflammatory cells and increases the expression of proinflammatory cytokines such as IL-6 and IL-23. So, the Th17/IL-17 axis is simultaneously the fuel and the flame of a sustained proinflammatory and profibrotic environment. This work aims to present the immunopathologic and prognostic role of the Th17/IL-17 axis and related pathways in fibrogenesis and progression to cirrhosis in patients with liver disease due to hepatitis B virus (HBV) and hepatitis C virus (HCV).