Fluctuating biomarkers in primary sclerosing cholangitis: A longitudinal comparison of alkaline phosphatase, liver stiffness, and ELF

RNA-binding protein transcripts as potential biomarkers for detecting Primary Sclerosing Cholangitis and for predicting its progression to Cholangiocarcinoma

Primary Sclerosing Cholangitis (PSC) is a persistent inflammatory liver condition that affects the bile ducts and is commonly diagnosed in young individuals. Despite efforts to incorporate various clinical, biochemical and molecular parameters for diagnosing PSC, it remains challenging, and no biomarkers characteristic of the disease have been identified hitherto. PSC is linked with an uncertain prognosis, and there is a pressing need to explore multiomics databases to establish a new biomarker panel for the early detection of PSC's gradual progression into Cholangiocarcinoma (CCA) and for the development of effective therapeutic interventions. Apart from non-coding RNAs, other components of the Ribonucleoprotein (RNP) complex, such as RNA-Binding Proteins (RBPs), also hold great promise as biomarkers due to their versatile expression in pathological conditions. In the present review, an update on the RBP transcripts that show dysregulated expression in PSC and CCA is provided. Moreover, by utilizing a bioinformatic data mining approach, we give insight into those RBP transcripts that also exhibit differential expression in liver and gall bladder, as well as in body fluids, and are promising as biomarkers for diagnosing and predicting the prognosis of PSC. Expression data were bioinformatically extracted from public repositories usingTCGA Bile Duct Cancer dataset for CCA and specific NCBI GEO datasets for both PSC and CCA; more specifically, RBPs annotations were obtained from RBP World database. Interestingly, our comprehensive analysis shows an elevated expression of the non-canonical RBPs, FANCD2, as well as the microtubule dynamics regulator, ASPM, transcripts in the body fluids of patients with PSC and CCA compared with their respective controls, with the same trend in expression being observed in gall bladder and liver cancer tissues. Consequently, the manipulation of tissue expression of RBP transcripts might be considered as a strategy to mitigate the onset of CCA in PSC patients, and warrants further experimental investigation. The analysis performed herein may be helpful in the identification of non-invasive biomarkers for the early detection of PSC and for predicting its progression into CCA. In conclusion, future clinical research should investigate in more depth the full potential of RBP transcripts as biomarkers for human pathologies.

Intelligent Liver Function Testing (iLFT): An Intelligent Laboratory Approach to Identifying Chronic Liver Disease

The intelligent Liver Function Testing (iLFT) pathway is a novel, algorithm-based system which provides automated laboratory investigations and clinical feedback on abnormal liver function test (LFT) results from primary care. iLFT was introduced to NHS Tayside, Scotland, in August 2018 in response to vast numbers of abnormal LFTs, many of which were not appropriately investigated, coupled with rising mortality from chronic liver disease. Here, we outline the development and implementation of the iLFT pathway, considering the implications for the diagnostic laboratories, primary care services and specialist hepatology clinics. Additionally, we describe the utility, outcomes and evolution of iLFT, which was used over 11,000 times in its first three years alone. Finally, we will consider the future of iLFT and propose areas where similar 'intelligent' approaches could be used to add value to laboratory investigations.

Prognostic models and autoimmune liver diseases

Autoimmune liver diseases (AILDs) are complex diseases with unknown causes and immune-mediated pathophysiology. In primary biliary cholangitis (PBC) and autoimmune hepatitis (AIH) disease modifying drugs are available which improve patient quality and quantity of life. In primary sclerosing cholangitis (PSC) no medical therapy is available and the only accepted treatment is liver transplantation (LT). PBC, PSC and AIH possess features that describe the archetype of patients within each disorder. On the other hand, the classical disorders are not homogeneous, and patients within each diagnosis may present with a range of clinical, biochemical, serological, and histological findings. Singularly, they are considered rare diseases, but together, they account for approximately 20% of LTs in Europe and USA. Management of these patients is complex, as AILDs are relatively uncommon in clinical practice with challenges in developing expertise, disease presentation can be sneaky, clinical phenotypes and disease course are heterogeneous. Prognostic models are key tools for clinicians to assess patients' risk and to provide personalized care to patients. Aim of this review is to discuss challenges of the management of AILDs and how the available prognostic models can help. We will discuss the prognostic models developed in AILDs, with a special focus on the prognostic models that can support the clinical management of patients with AILDs: in PBC models based on ursodeoxycholic acid (UDCA) response and markers of liver fibrosis; in PSC several markers including biochemistry, disease stage and radiological semiquantitative markers; and finally in AIH, markers of disease stage and disease activity.

ANXA1 is identified as a key gene associated with high risk and T cell infiltration in primary sclerosing cholangitis

BACKGROUND

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease, with unclear pathogenesis. Although immune disorders, especially T cell infiltration, are thought to play a vital role in PSC, the specific pathogenesis mechanisms remain incompletely understood. This study evaluated the potential key gene associated with the PSC pathogenesis and analyzed the associations of the key gene with prognosis and immune cell infiltration by combining bioinformatics analysis and experimental verification.

METHODS

Transcriptome data of PSC and normal human liver tissues (GSE159676) were obtained from the gene expression omnibus database. Differentially expressed genes (DEGs) were identified, and differences in biological states were analyzed. A protein-protein interaction (PPI) network was constructed. Hub genes were identified, and their expression was verified using transcriptome data of mice fed 0.1% 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) and Mdr2-/- mice (GSE179993, GSE80776), as well as by immunohistochemistry staining on clinical samples. The correlations between the key gene and other factors were evaluated by Pearson's correlation coefficient. Immune cell infiltration into human liver (GSE159676) was analyzed by xCell and verified by immunofluorescence staining on PSC liver samples.

RESULTS

Of the 185 DEGs identified, 113 were upregulated and 72 were downregulated genes in PSC. Genes associated with immune cell infiltration and fibrosis were significantly enriched in PSC. PPI network showed close interactions among DEGs. A module strongly associated with immune infiltration was identified, with annexin A1 (ANXA1) being the core gene. High expression of ANXA1 in PSC was confirmed in two public datasets and by immunohistochemistry staining on clinical samples. High ANXA1 expression was strongly associated with high-risk score for PSC. Also, ANXA1 expression was positively associated with chemokines and chemokine receptors and with the infiltration of immune cells, especially T cells, into liver with PSC. Immune infiltration, fibrosis, and cancer-related processes were markedly enriched in PSC with high expression of ANXA1.

CONCLUSION

ANXA1 is a key gene associated with high risk and infiltration of immune cells, especially T cells, in PSC. These findings provide new insight into the key biomarker of PSC and suggest that targeting ANXA1 may be a valuable strategy for the treatment of PSC.

The role of serology, liver function tests and imaging in screening of primary sclerosing cholangitis: the HelPSCreen score

OBJECIVES

At present, no sensitive or specific screening test exists for primary sclerosing cholangitis (PSC). PSC screening is mainly based on elevated alkaline phosphatase (ALP) in patients with inflammatory bowel disease (IBD). We aimed to produce a screening score based on laboratory tests to predict the likelihood of PSC. Moreover, we evaluated the additional roles of liver histology and magnetic resonance cholangiopancreatography (MRCP) in the diagnosis of PSC.

MATERIALS AND METHODS

The data of 385 patients who came for their first endoscopic retrograde cholangiography (ERC) to confirm PSC diagnosis were retrieved from the PSC registry of the Helsinki University Hospital. Overall, 69 patients referred for ERC with suspected PSC, in whom PSC was excluded by ERC or liver biopsy and MRCP, served as controls. We included patients' demographics and 13 laboratory test results in the analysis. Variables with significant odds ratios were selected for multivariate logistic regression, which was used to create a novel scoring system for PSC. The presence of IBD, serum perinuclear anti-neutrophil cytoplasmic antibodies, and ALP levels demonstrated the highest predictive value for PSC. A score was assigned for each statistically significant predictor.

RESULTS

The optimal cut-off point for the score was ≥3, with an AUC of 0.83 (95%CI: 0.78-0.88). The addition of liver histology or MRCP findings to the score did not add a predictive value.

CONCUSIONS

In conclusion, we created a novel, simple scoring system to screen the probability of PSC. The HelPSCreen-score may help to assess the disease prevalence and to target further investigations in patients suspected of PSC.

Quantification of extracellular matrix remodeling for the non-invasive identification of graft fibrosis after liver transplantation

Detecting patients with early post-transplant fibrosis after liver transplantation (LT) is very important. Non-invasive tests are needed to avoid liver biopsies. We aimed to detect fibrosis in liver transplant recipients (LTR) using extracellular matrix (ECM) remodeling biomarkers. ECM biomarkers for type III (PRO-C3), IV (PRO-C4), VI (PRO-C6) and XVIII (PRO-C18L) collagen formation and type IV collagen degradation (C4M) were measured by ELISA in prospectively collected, cryopreserved plasma samples (n = 100) of LTR with paired liver biopsies from a protocol biopsy program. Fibrosis ≥ F2 was present in 29% of patients (median 44 months post-LT). APRI and FIB-4 neither identified significant fibrosis nor were correlated with histopathological fibrosis scores, while ECM biomarkers (AUCs 0.67-0.74) did. The median levels of PRO-C3 (15.7 vs. 11.6 ng/ml; p = 0.002) and C4M (22.9 vs. 11.6 ng/ml; p = 0.006) levels were elevated in T-cell-mediated rejection compared to normal graft function. The median levels of PRO-C4 (178.9 vs. 151.8 ng/ml; p = 0.009) and C4M (18.9 vs. 16.8 ng/ml; p = 0.004) levels were increased if donor-specific antibodies were present. PRO-C6 had the highest sensitivity (100%), NPV (100%) and negative likelihood-ratio (0) for graft fibrosis. To conclude, ECM biomarkers are helpful in identifying patients at risk of relevant graft fibrosis.

Noninvasive evaluation of fibrosis in adult biliary diseases

PURPOSE OF REVIEW

Liver fibrosis is highly associated with disease progression and clinical outcome in primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC), the major chronic biliary diseases in adults. Establishment of validated tools for the noninvasive evaluation of liver fibrosis in PBC and PSC for use in patient follow-up, and effect evaluation in clinical trials, has been a top research priority over recent years.

RECENT FINDINGS

Two studies in large PBC patient panels investigated liver stiffness measurement by vibration-controlled transient elastography (VCTE) and two studies in PSC demonstrated enhanced liver fibrosis (ELF) variation over time, confirming VCTE and ELF as good prognostic markers. Currently, magnetic resonance elastography (MRE), quantitative MRI mapping and novel serum extracellular matrix and extracellular vesicle markers show promising results for fibrosis and prognostic assessment in biliary diseases.

SUMMARY

In this article, we will briefly review recent studies supporting recommendations to assess liver fibrosis and prognosis using the ELF test and VCTE during clinical follow-up in both PBC and PSC. We will discuss emerging evidence for MRE and other imaging techniques, and novel serum fibrosis markers, for which sufficient data or availability is currently limited precluding recommendations for clinical use.

Factors other than fibrosis that increase measured shear wave velocity

Shear wave elastography (SWE) is now becoming an indispensable diagnostic tool in the routine examination of liver diseases. In particular, accuracy is required for shear wave propagation velocity measurement, which is directly related to diagnostic accuracy. It is generally accepted that the liver shear wave propagation velocity reflects the degree of fibrosis, but there are still few reports on other factors that increase the shear wave propagation velocity. In this study, we reviewed such factors in the literature and examined their mechanisms. Current SWE measures propagation velocity based on the assumption that the medium has a homogeneous structure, uniform density, and is purely elastic. Otherwise, the measurement is subject to error. The other (confounding) factors that we routinely experience are primarily: (1) Conditions that appear to increase the viscous component; and (2) Conditions that appear to increase tissue density. Clinically, the former includes acute hepatitis, congested liver, biliary obstruction, etc, and the latter includes diffuse infiltration of malignant cells, various storage diseases, tissue necrosis, etc. In any case, it is important to evaluate SWE in the context of the entire clinical picture.

Serological biomarkers for management of primary sclerosing cholangitis

Clinical manifestations and progression of primary sclerosing cholangitis (PSC) are heterogeneous, and its pathogenesis is poorly understood. The importance of gut-liver interactions in the pathogenesis has been clinically confirmed and highlighted in different theories. Recent advances regarding biomarkers of biliary-gut crosstalk may help to identify clinically relevant PSC subgroups assisting everyday clinical work-up (e.g., diagnosis, disease stratification, or surveillance) and the exploration of potential therapeutic targets. Alkaline phosphatase produced by the biliary epithelium is consistently associated with prognosis. However, its level shows natural fluctuation limiting its use in individual patients. Inflammatory, cell activation, and tissue remodeling markers have been reported to predict clinical outcome. Elevated immunoglobulin (Ig) G4 level is associated with a shorter transplantation-free survival. IgG type atypical perinuclear anti-neutrophil cytoplasmic antibodies (P-ANCAs) are non-specific markers of various autoimmune liver diseases and may reflect an abnormal B-cell response to gut microbial antigens. IgG type atypical P-ANCA identifies PSC patients with particular clinical and genetic (for human leukocyte antigens) characteristics. The presence of IgA type anti-F-actin antibody (AAA) may predict a progressive disease course, and it is associated with enhanced mucosal immune response to various microbial antigens and enterocyte damage. IgA type anti-glycoprotein 2 (GP2) antibodies identify patients with a severe disease phenotype and poor survival due to enhanced fibrogenesis or development of cholangiocarcinoma. Elevated soluble vascular adhesion protein-1 (sVAP-1) level is associated with adverse disease outcomes in PSC. High sVAP-1 levels correlate with mucosal addressin cell adhesion molecule-1 (MAdCAM-1) expression in the liver that contributes to gut activated T-cell homing to the hepatobiliary tract. In the present paper, we review the evidence on these possible serological markers that could potentially help address the unmet clinical needs in PSC.

Soluble Urokinase Plasminogen Activator Receptor Levels Are Associated with Severity of Fibrosis in Patients with Primary Sclerosing Cholangitis

The soluble urokinase-type plasminogen activator receptor (suPAR) has evolved as a useful biomarker for different entities of chronic liver disease. However, its role in patients with primary sclerosing cholangitis (PSC) is obscure. We analyzed plasma levels of suPAR in 84 patients with PSC and compared them to 68 patients with inflammatory bowel disease (IBD) without PSC and to 40 healthy controls. Results are correlated with clinical records. suPAR concentrations were elevated in patients with PSC compared to patients with IBD only and to healthy controls (p < 0.001). Elevated suPAR levels were associated with the presence of liver cirrhosis (p < 0.001) and signs of portal hypertension (p < 0.001). suPAR revealed a high accuracy for the discrimination of the presence of liver cirrhosis comparable to previously validated noninvasive fibrosis markers (area under the curve (AUC) 0.802 (95%CI: 0.702−0.902)). Further, we demonstrated that suPAR levels may indicate the presence of acute cholangitis episodes (p < 0.001). Finally, despite the high proportion of PSC patients with IBD, presence of IBD and its disease activity did not influence circulating suPAR levels. suPAR represents a previously unrecognized biomarker for diagnosis and liver cirrhosis detection in patients with PSC. However, it does not appear to be confounded by intestinal inflammation in the context of IBD.