Primary Sclerosing Cholangitis and Inflammatory Bowel Disease: A Review

Bioinformatics analysis reveals shared molecular pathways for relationship between ulcerative colitis and primary sclerosing cholangitis

BACKGROUND

Inflammatory bowel disease (IBD) is a group of chronic inflammatory disorders, including ulcerative colitis (UC) and Crohn's disease, affecting the gastrointestinal tract and is associated with high morbidity and mortality. Accumulating evidence indicates that IBD not only impacts the gastrointestinal tract but also affects multiple extraintestinal organs, which may manifest prior to the diagnosis of IBD. Among these extraintestinal manifestations associated with IBD, primary sclerosing cholangitis (PSC) stands out as a prominent example. PSC is recognized as a progressive cholestatic disorder, characterized by the narrowing of bile ducts, eventual development of liver cirrhosis, end-stage liver disease, and the potential emergence of cholangiocarcinoma. This study aimed to identify the molecular contributors in UC-induced PSC by detecting the essential regulatory genes that are differentially expressed in both diseases.

MATERIALS AND METHODS

The common single-nucleotide polymorphisms (SNPs) and differentially expressed genes (DEGs) were detected using DisGeNET and GEO databases, respectively. Then, the top module and hub genes within the protein-protein interaction network were identified. Furthermore, the co-expression network of the top module was constructed using the HIPPIE database. Additionally, the gene regulatory network was constructed based on miRNAs and circRNAs. Finally, we searched the DGIdb database for possible interacting drugs with UC-PSC top module genes.

RESULTS

A total of 132 SNPs and their associated genes were found to be shared between UC and PSC. Gene expression analysis identified 56 common DEGs between the two diseases. Following functional enrichment analysis, 207 significant biological processes (BP), 48 molecular functions (MF), and 8 KEGG pathways, with notable enrichment in mRNA-related processes such as mRNA splicing and RNA binding, were defined. Particularly, the PTPN2 gene was the only gene common between UC and PSC at both the SNP level and the expression level. Additionally, the top cluster of PPI network analysis was consisted of PABPC1, SNRPA1, NOP56, NHP2L1, and HNRNPA2B1 genes. Finally, ceRNA network involving 4 mRNAs, 94 miRNAs, and 200 selected circRNAs was constructed.

CONCLUSION

The present study provides novel potential candidate genes that may be involved in the molecular association between ulcerative colitis and primary sclerosing cholangitis, resulting in the development of diagnostic tools and therapeutic targets to prevent the progression of PSC from UC.

Mycobiota and Antifungal Antibodies as Emerging Targets for the Diagnosis and Prognosis of Human Diseases

The human body is colonized by diverse microorganisms, with bacteria being the most extensively studied. However, fungi, collectively known as "the mycobiota," are increasingly recognized as integral components of the microbiota, inhabiting nearly all mucosal surfaces. Commensal fungi influence host immunity similarly to bacteria and contribute to other essential functions, including metabolism. This emerging understanding positions fungi as potential biomarkers for the diagnosis and prognosis of various diseases. In this review, we explore the dual roles of fungi as both commensals and pathogens, and the potential of antifungal antibodies to serve as diagnostic and prognostic tools, especially in chronic immune-inflammatory non-communicable diseases, including inflammatory bowel disease, rheumatoid arthritis, multiple sclerosis, and neurodegenerative disorders. Finally, we address current challenges and outline future perspectives for leveraging fungal biomarkers in clinical practice.

[Position statement of the Spanish Society of Primary Care Physicians (SEMERGEN) and Spanish Working Group on Crohn's Disease and Ulcerative Colitis (GETECCU) on the management of inflammatory bowel disease in Primary Care]

Primary Care is the first point of contact for most patients after the onset of symptoms of inflammatory bowel disease (IBD). Establishing an initial diagnostic process based on compatible symptoms and agreed criteria and referral pathways, depending on the degree of suspicion and the patient's situation, can reduce diagnostic delays. Once the patient is referred to the Digestive specialist and the diagnosis of IBD is established, a treatment and follow-up plan is structured. The management of the patient must be shared with the participation of the family practitioners in the diagnosis and treatment of concomitant or intercurrent pathologies, the recognition of flare-ups or complications (of IBD or treatments), education tasks or adherence control. With the purpose of developing a comprehensive guide on the management of IBD aimed at Primary Care doctors, we have developed this positioning document collaboratively between the Spanish Society of Primary Care Physicians (SEMERGEN) and the Spanish Working Group on Crohn's Disease and Ulcerative Colitis (GETECCU).

The causal impact of genetically predicted inflammatory bowel disease on extraintestinal manifestations: a mendelian randomization study

BACKGROUND

Extraintestinal manifestations (EIMs) significantly affect the life quality of people with inflammatory bowel disease (IBD) and are crucial factors impacting occurrence rates and mortality among IBD patients. This study performed a Mendelian randomization (MR) analysis to investigate the causal relationships between genetically predicted IBD and the development of EIMs, including erythema nodosum (EN), episcleritis, scleritis, uveitis, primary sclerosing cholangitis (PSC), and spondyloarthritis. To further investigate differences between subtypes, separate analyses were conducted for ulcerative colitis (UC) and Crohn's disease (CD).

METHODS

The study was conducted based on genome-wide association studies (GWAS) data. We carefully selected SNPs associated with both exposure and outcome by comparing and integrating data from GWAS and relevant literature, and prioritizing studies with large sample sizes, high quality, and as much population homogeneity as possible. The SNPs associated with IBD, UC and CD were extracted from the International Inflammatory Bowel Disease Genetics Consortium. And the SNPs associated with EIMs were extracted from the UK Biobank, the International PSC Study Group and the FinnGen study. A series of quality control steps were taken in our analysis to select eligible instrumental SNPs which were strongly associated with exposure. The causal effects were estimated using a primary analysis that employed inverse-variance weighting (IVW) and complementary analysis that utilized MR-Egger weighted by the median. A sensitivity analysis was conducted using the Cochran Q statistic, a funnel plot, the MR-Egger intercept, and a leave-one-out approach. Reverse causality analysis was also performed to ensure the robustness of the findings. Furthermore, a fixed-effects meta-analysis was employed to combine MR outcomes from various data origins, bolstering the strength and dependability of our findings.

RESULTS

Our findings indicated that genetically predicted IBD had a robust causal relationship with an increased risk of specific conditions, including EN (OR, 1.20; 95% CI, 1.09-1.32; p < 0.01), uveitis (OR, 1.15; 95% CI, 1.11-1.20; p < 0.01), PSC (OR, 1.21; 95% CI, 1.13-1.28; p < 0.01), and spondyloarthritis (OR, 1.19; 95% CI, 1.14-1.23; p < 0.01). In subgroup analyses, the causal effects of both UC and CD on EN, uveitis, PSC, and spondyloarthritis were also significant and robust. Additionally, no significant evidence of causality was observed between genetically predicted IBD, UC, and CD, and the occurrence of both episcleritis and scleritis. The results of reverse causality analysis indicated a robust causal association between genetically predicted PSC and the elevated risk of IBD (OR, 1.21; 95% CI, 1.15-1.29; p < 0.01), UC (OR, 1.27; 95% CI, 1.17-1.37; p < 0.01), and CD (OR, 1.10; 95% CI, 1.02-1.20; p < 0.01). Additionally, spondyloarthritis had a causal relationship with an increased risk of both IBD (OR, 1.03; 95% CI, 1.01-1.06; p < 0.01) and UC (OR, 1.05; 95% CI, 1.02-1.08; p < 0.01).

Assessing brodalumab in the treatment of primary sclerosing cholangitis (SABR-PSC pilot study): protocol for a single-arm, multicentre, pilot study

INTRODUCTION

Primary sclerosing cholangitis (PSC) is a rare immune-mediated hepatobiliary disease, characterised by progressive biliary fibrosis, cirrhosis, and end-stage liver disease. As yet, no licensed pharmacological therapy exists. While significant advancements have been made in our understanding of the pathophysiology, the exact aetiology remains poorly defined. Compelling evidence from basic science and translational studies implicates the role of T helper 17 cells (Th17) and the interleukin 17 (IL-17) pro-inflammatory signalling pathway in the pathogenesis of PSC. However, exploration of the safety and efficacy of inhibiting the IL-17 pathway in PSC is lacking.

METHODS AND ANALYSIS

This is a phase 2a, open-label, multicentre pilot study, testing the safety of brodalumab, a recombinant human monoclonal antibody that binds with high affinity to interleukin-17RA, in adults with PSC. This study will enrol 20 PSC patients across five large National Health Service tertiary centres in the UK. The primary outcome of the study relates to determining the safety and feasibility of administering brodalumab in early, non-cirrhotic PSC patients. Secondary efficacy outcomes include non-invasive assessment of liver fibrosis, changes in alkaline phosphatase values and other liver biochemical readouts, assessment of biliary metrics through quantitative MR cholangiography+, and quality of life evaluation on completion of follow-up (using the 5D-itch tool, the PSC-patient-reported outcome and PSC-specific Chronic Liver Disease Questionnaire).

ETHICS AND DISSEMINATION

Ethical approval for this study has been obtained from the London Bridge Research Ethics Committee (REC23/LO/0718). Written informed consent will be obtained from all trial participants prior to undertaking any trial-specific examinations or investigations. On completion of the study, results will be submitted for publication in peer-reviewed journals and presented at national and international hepatology meetings. A summary of the findings will also be shared with participants and PSC communities.

TRIAL REGISTRATION NUMBER

ISRCTN15271834.

Position statement of the Spanish Society of Primary Care Physicians (SEMERGEN) and Spanish Working Group on Crohn's Disease and Ulcerative Colitis (GETECCU) on the management of inflammatory bowel disease in Primary Care

Primary Care is the first point of contact for most patients after the onset of symptoms of inflammatory bowel disease (IBD). Establishing an initial diagnostic process based on compatible symptoms and agreed criteria and referral pathways, depending on the degree of suspicion and the patient's situation, can reduce diagnostic delays. Once the patient is referred to the Digestive specialist and the diagnosis of IBD is established, a treatment and follow-up plan is structured. The management of the patient must be shared with the participation of the family practitioners in the diagnosis and treatment of concomitant or intercurrent pathologies, the recognition of flare-ups or complications (of IBD or treatments), education tasks or adherence control. With the purpose of developing a comprehensive guide on the management of IBD aimed at Primary Care doctors, we have developed this positioning document collaboratively between the Spanish Society of Primary Care Physicians (SEMERGEN) and the Spanish Working Group on Crohn's Disease and Ulcerative Colitis (GETECCU).

Hepatobiliary and pancreatic manifestations in inflammatory bowel disease: an umbrella review of meta-analyses

Background

Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), can affect the hepatobiliary system and pancreas, substantially impacting the life quality of patients.

Objectives

To evaluate the quality of evidence and comprehensively assess the validity of associations of IBD with hepatobiliary and pancreatic diseases.

Design

We performed an umbrella review of existing meta-analyses in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) recommendations.

Data sources and methods

We systematically searched PubMed, Embase, and Web of Science from inception to April 2024, to identify and appraise meta-analyses examining IBD and risk of hepatobiliary and pancreatic manifestations. Methodologic quality was assessed with A Measurement Tool to Assess Systematic Reviews (AMSTAR 2) and the strength of evidence was graded according to prespecified criteria.

Results

A total of 14 meta-analyses of observational studies were included. The strongest-validity evidence suggested the significant associations between IBD and risk of gallstones (odds ratio (OR) = 1.72; 95% confidence interval (CI) = 1.40-2.12) and acute pancreatitis (OR = 3.11; 95% CI = 2.93-3.30). Highly suggestive evidence indicated a significantly increased risk of hepatobiliary cancer in UC (incidence rate ratio (IRR) = 2.05; 95% CI = 1.52-2.76) and CD (IRR = 2.31; 95% CI = 1.25-4.28). In addition, highly suggestive evidence indicated that IBD was associated with portal venous system thrombosis. Suggestive evidence showed a significantly higher prevalence of primary sclerosing cholangitis, non-alcoholic fatty liver disease, autoimmune hepatitis, and autoimmune pancreatitis in IBD patients than in the general population.

Conclusion

The associations between IBD and multiple hepatobiliary and pancreatic disorders showed varying levels of evidence and magnitude of risk. Further high-quality primary studies are needed to identify IBD patients who are more at risk and would benefit the most from screening and prevention programs.

Trial registration PROSPERO

CRD42023451461.

Clinical Impact of Primary Sclerosing Cholangitis on Outcomes of Inflammatory Bowel Disease Hospitalization: A Propensity Score Matching Analysis of the Nationwide Inpatient Sample

OBJECTIVE

We aimed to evaluate the effect of primary sclerosing cholangitis (PSC) on hospitalization outcomes of inflammatory bowel disease (IBD) patients.

METHODS

This retrospective study used data from the Nationwide Inpatient Sample (NIS) database from January 1, 2019, to December 31, 2020, including adults (≥ 18 years) admitted and diagnosed with IBD. Key outcomes included length of hospital stay (LOS), in-hospital mortality, hospitalization cost, and complications. The propensity score matching (PSM) analysis was used to balance characteristics between IBD patients with and without PSC, followed by logistic regression for analysis.

RESULTS

After PSM analysis, 4950 patients (PSC: 990; non-PSC: 3960) were analyzed. IBD patients with PSC showed higher odds of any complication (odds ratio [OR] 2.08, 95% confidence interval [CI] 1.80-2.39), including acute kidney injury (OR 1.31, 95% CI 1.10-1.55), septic shock (OR 1.84, 95% CI 1.33-2.54), liver cirrhosis (OR 18.19, 95% CI 14.23-23.25), and liver failure (OR 8.33, 95% CI 5.93-11.70) (all p < 0.05). These associations were consistently observed across subgroups with stronger associations in the Crohn's disease subgroup.

CONCLUSIONS

PSC significantly increases the risk of short-term complications in hospitalized IBD patients and the likelihood of chronic liver disease-related complications. These findings highlight the need for targeted management strategies for IBD patients with co-existing PSC.

The mediating role of primary sclerosing cholangitis in the association between ulcerative colitis and hepatobiliary cancer investigated through Mendelian randomization

This study explored the causal relationships among primary sclerosing cholangitis (PSC), ulcerative colitis (UC), and hepatobiliary cancer (HBC) by using bidirectional two-sample, two-step Mendelian randomization (MR) analysis. Genetic variants associated with PSC and UC from the FinnGen research database were used for instrumental variable-based analyses. Mediation analyses were conducted to examine the role of PSC and UC in HBC risk. The findings revealed a causal effect of genetic predisposition to UC on PSC risk (inverse-variance-weighted [IVW] analysis odds ratio [OR] 1.145, p < 0.001), whereas no reverse causality was observed. Although UC showed no direct causal effect on HBC risk, genetic susceptibility to PSC significantly increased the risk of HBC (IVW analysis OR = 1.855, p < 0.001). Mediation analysis further identified PSC as a significant mediator amplifying the causal effect of UC on HBC risk (effect size = 0.083). These results established a causal link between genetic susceptibility to UC and increased risk of PSC, and highlighted the critical role of PSC in mediating the impact of UC on HBC risk.

The Effectiveness of Oral Vancomycin on Inflammatory Bowel Disease in Patients With Primary Sclerosing Cholangitis: A Systematic Review

BACKGROUND

Approximately 70% of primary sclerosing cholangitis (PSC) patients have inflammatory bowel disease (IBD). The IBD therapies currently used to treat PSC-IBD patients have side effects and can be costly. Oral vancomycin (OV)-a safe, economical, and convenient therapy-has been reported to be a salvage therapy in refractory PSC-IBD patients. This systematic review aims to summarize the current literature regarding the effectiveness and safety of OV to treat IBD in PSC patients.

METHODS

A systematic literature review of Scopus, Embase, Web of Science, MEDLINE, and CINAHL was performed until March 2024. The Murad scale, Newcastle-Ottawa scale, and Cochrane Collaboration Risk of Bias Tool were used to determine the quality of the case reports and case series, cohort studies, and randomized controlled trial (RCT), respectively. The outcomes sought were response or remission across clinical, biochemical, endoscopic, and histological parameters.

RESULTS

Of the 1725 published studies, we identified 9 case reports, 7 case series, 3 cohort studies, and 1 RCT. Most studies reported an improvement in clinical IBD symptoms such as diarrhea and hematochezia. Fewer publications provided supporting objective data in the form of fecal calprotectin, endoscopic Mayo scores, and histology. There were no reports of vancomycin-resistant enterococci infections.

CONCLUSIONS

Oral vancomycin appears safe and effective to treat IBD in a subset of PSC patients. Future studies would benefit from prospective data collection incorporating standardized symptomatic, endoscopic, and histologic indices. Ultimately, a well-powered RCT is needed to better assess the effectiveness, safety, and durability of OV therapy.

Cilofexor in Patients With Compensated Cirrhosis Due to Primary Sclerosing Cholangitis: An Open-Label Phase 1B Study

INTRODUCTION

This proof-of-concept, open-label phase 1b study evaluated the safety and efficacy of cilofexor, a potent selective farnesoid X receptor agonist, in patients with compensated cirrhosis due to primary sclerosing cholangitis.

METHODS

Escalating doses of cilofexor (30 mg [weeks 1-4], 60 mg [weeks 5-8], 100 mg [weeks 9-12]) were administered orally once daily over 12 weeks. The primary endpoint was safety. Exploratory measures included cholestasis and fibrosis markers and pharmacodynamic biomarkers of bile acid homeostasis.

RESULTS

Eleven patients were enrolled (median age: 48 years; 55% men). The most common treatment-emergent adverse events (TEAEs) were pruritus (8/11 [72.7%]), fatigue, headache, nausea, and upper respiratory tract infection (2/11 [18.2%] each). Seven patients experienced a pruritus TEAE (one grade 3) considered drug-related. One patient temporarily discontinued cilofexor owing to peripheral edema. There were no deaths, serious TEAEs, or TEAEs leading to permanent discontinuation. Median changes (interquartile ranges) from baseline to week 12 (predose, fasting) were -24.8% (-35.7 to -7.4) for alanine transaminase, -13.0% (-21.9 to -8.6) for alkaline phosphatase, -43.5% (-52.1 to -30.8) for γ-glutamyl transferase, -12.7% (-25.0 to 0.0) for total bilirubin, and -21.2% (-40.0 to 0.0) for direct bilirubin. Least-squares mean percentage change (95% confidence interval) from baseline to week 12 at trough was -55.3% (-70.8 to -31.6) for C4 and -60.5% (-81.8 to -14.2) for cholic acid. Fasting fibroblast growth factor 19 levels transiently increased after cilofexor administration.

DISCUSSION

Escalating doses of cilofexor over 12 weeks were well tolerated and improved cholestasis markers in patients with compensated cirrhosis due to primary sclerosing cholangitis (NCT04060147).

Protective function of sclerosing cholangitis on IBD

OBJECTIVE

There is a strong clinical association between IBD and primary sclerosing cholangitis (PSC), a chronic disease of the liver characterised by biliary inflammation that leads to strictures and fibrosis. Approximately 60%-80% of people with PSC will also develop IBD (PSC-IBD). One hypothesis explaining this association would be that PSC drives IBD. Therefore, our aim was to test this hypothesis and to decipher the underlying mechanism.

DESIGN

Colitis severity was analysed in experimental mouse models of colitis and sclerosing cholangitis, and people with IBD and PSC-IBD. Foxp3+ Treg-cell infiltration was assessed by qPCR and flow cytometry. Microbiota profiling was carried out from faecal samples of people with IBD, PSC-IBD and mouse models recapitulating these diseases. Faecal microbiota samples collected from people with IBD and PSC-IBD were transplanted into germ-free mice followed by colitis induction.

RESULTS

We show that sclerosing cholangitis attenuated IBD in mouse models. Mechanistically, sclerosing cholangitis causes an altered intestinal microbiota composition, which promotes Foxp3+ Treg-cell expansion, and thereby protects against IBD. Accordingly, sclerosing cholangitis promotes IBD in the absence of Foxp3+ Treg cells. Furthermore, people with PSC-IBD have an increased Foxp3+ expression in the colon and an overall milder IBD severity. Finally, by transplanting faecal microbiota into gnotobiotic mice, we showed that the intestinal microbiota of people with PSC protects against colitis.

CONCLUSION

This study shows that PSC attenuates IBD and provides a comprehensive insight into the mechanisms involved in this effect.

Ketamine-Induced Sclerosing Cholangitis Associated With Early Inflammatory Bowel Disease During Chronic Topical Ketamine Use

Ketamine-induced sclerosing cholangitis has been described with chronic intranasal and intravenous use. Our case follows chronic topical use for peripheral neuropathy. It is also uniquely associated with early inflammatory bowel disease, a known complication of primary sclerosing cholangitis.

Investigating the shared genetic architecture between primary sclerosing cholangitis and inflammatory bowel diseases: a Mendelian randomization study

BACKGROUND

Several studies have found that primary sclerosing cholangitis (PSC) and inflammatory bowel disease (IBD) are closely associated. However, the direction and causality of their interactions remain unclear. Thus, this study employs Mendelian Randomization to explore whether there are causal associations of genetically predicted PSC with IBD.

METHODS

Genetic variants associated with the genome-wide association study (GWAS) of PSC were used as instrumental variables. The statistics for IBD, including ulcerative colitis (UC), and Crohn's disease (CD) were derived from GWAS. Then, five methods were used to estimate the effects of genetically predicted PSC on IBD, including MR Egger, Weighted median (WM), Inverse variance weighted (IVW), Simple mode, and Weighted mode. Last, we also evaluated the pleiotropic effects, heterogeneity, and a leave-one-out sensitivity analysis that drives causal associations to confirm the validity of the analysis.

RESULTS

Genetically predicted PSC was significantly associated with an increased risk of UC, according to the study (odds ratio [OR] IVW= 1.0014, P<0.05). However, none of the MR methods found significant causal evidence of genetically predicted PSC in CD (All P>0.05). The sensitivity analysis results showed that the causal effect estimations of genetically predicted PSC on IBD were robust, and there was no horizontal pleiotropy or statistical heterogeneity.

CONCLUSIONS

Our study corroborated a causal association between genetically predicted PSC and UC but did not between genetically predicted PSC and CD. Then, we identification of shared SNPs for PSC and UC, including rs3184504, rs9858213, rs725613, rs10909839, and rs4147359. More animal experiments and clinical observational studies are required to further clarify the underlying mechanisms of PSC and IBD.

Gastric metaplasia as a precursor of nonconventional dysplasia in inflammatory bowel disease

Gastric metaplasia in colonic mucosa with inflammatory bowel disease (IBD) develops as an adaptation mechanism. The association between gastric metaplasia and nonconventional and/or conventional dysplasia as precursors of colitis-associated colorectal cancer is unknown. To address this question, we retrospectively reviewed a series of 33 IBD colectomies to identify gastric metaplasia in 76 precursor lesions. We obtained 61 nonconventional and 15 conventional dysplasias. Among nonconventional dysplasia, 31 (50.8 %) were low-grade (LGD), 4 (6.5 %) were high-grade (HGD), 9 (14.8 %) had both LGD and HGD, and 17 (27.9 %) had no dysplasia (ND), while 14 (93 %) conventional dysplasias had LGD, and 1 (7 %) had LGD and HGD. Gastric metaplasia was assessed by concomitant immunoexpression of MUC5AC and loss of CDX2 staining. Expression of a p53-mut pattern was considered as a surrogate for gene mutation, and complete loss of MLH1 staining as presence of MLH1 hypermethylation. In nonconventional dysplasia, MUC5AC immunoexpression decreased as the degree of dysplasia increased, being 78 % in LGD and 39 % in HGD (p = 0.006). CDX2 was lost in epithelial glands with high expression of MUC5AC (p < 0.001). The p53-mut pattern was observed in 77 % HGD, 45 % LGD, and in 6 % with ND (p < 0.001). Neither nonconventional nor conventional dysplasia showed complete loss of MLH1 staining. Gastric metaplasia was also present in mucosa adjacent to nonconventional dysplasia with chronic changes or active inflammation. Our results show that gastric metaplasia appears in IBD-inflamed colon mucosa, it is the substrate of most nonconventional dysplasia and occurs prior to p53 alterations.

Bile Acids in Autoimmune Liver Disease: Unveiling the Nexus of Inflammation, Inflammatory Cells, and Treatment Strategies

As bile acids not solely play an essential role in nutrition absorption, but also in regulating metabolic functions as well as immune response, bile acids and their signaling pathways are increasingly acknowledged as potential therapeutic targets in the context of chronic liver diseases. Bile acid receptors such as G protein bile acid-activated receptor 1 and farnesoid X receptor are expressed in different immune cells engaged in innate immunity. Recently, a series of studies have revealed distinct functions of bile acids and bile acid receptors within the adaptive immune system. In addition, a variety of molecules targeting bile acid receptors and transporters are currently in advanced stages of clinical development. Autoimmune liver diseases including conditions like primary biliary cholangitis, primary sclerosing cholangitis, and autoimmune hepatitis can lead to chronic inflammation, fibrosis, and even cirrhosis and liver failure. In this review, we focus on the role of bile acids in the inflammatory aspects of autoimmune liver diseases.

Interaction between intratumoral microbiota and tumor mediates the response of neoadjuvant therapy for rectal cancer

Background

Previous observations have demonstrated that the response to neoadjuvant chemoradiotherapy (nCRT) is highly variable in patients with locally advanced rectal cancer (LARC). Recent studies focusing on the intratumoral microbiota of colorectal cancer have revealed its role in oncogenesis and tumor progression. However, limited research has focused on the influence of intratumoral microbiota on the nCRT of LARC.

Methods

We explored the microbial profiles in the tumor microenvironment of LARC using RNA-seq data from a published European cohort. Microbial signatures were characterized in pathological complete response (pCR) and non-pCR groups. Multi-omics analysis was performed between intratumor microbiomes and transcriptomes.

Results

Microbial α and β diversity were significantly different in pCR and non-pCR groups. Twelve differential microbes were discovered between the pCR and non-pCR groups, six of which were related to subclusters of cancer-associated fibroblasts (CAFs) associated with extracellular matrix formation. A microbial risk score based on the relative abundance of seven differential microbes had predictive value for the nCRT response (AUC = 0.820, p < 0.001).

Conclusion

Our study presents intratumoral microbes as potential independent predictive markers for the response of nCRT to LARC and demonstrates the underlying mechanism by which the interaction between intratumoral microbes and CAFs mediates the response to nCRT.

Updates in toxicities associated with immune checkpoint inhibitors

INTRODUCTION

Immune checkpoint inhibitors (ICIs) have become a pillar of treatment for numerous cancers with increasing use in combination with other ICIs and in earlier stages of disease treatment. Although effective, ICI use is accompanied by a milieu of potentially bothersome or even life-threatening toxicities known as immune-related adverse events (irAEs), necessitating careful monitoring and early intervention.

AREAS COVERED

In this review, we provide an overview of recent advances surrounding toxicity pathophysiology and treatment in the context of relevant organ systems. An emphasis on current treatments by toxicity, as well as updates on steroid-refractory toxicities, chronic toxicities, and biomarkers will be a focus of this update on the current understanding of irAEs.

EXPERT OPINION

ICI toxicities are a major limitation on the deployment of multi-agent ICI regimens and are thus a major priority to understand, treat, and prevent. Recent developments have led to greater understanding of the pathophysiology of these events, which may lead to improved prevention or mitigation strategies. Further, early studies have also suggested steroid-sparing approaches that may be useful. Ultimately, preventing and managing irAEs will be a key goal toward successful ICI treatment across a broader range of patients with cancer.

Association of serum IgG4 and disease outcomes in patients with inflammatory bowel disease

Background

The etiology of inflammatory bowel disease (IBD) is multifactorial and thought to be influenced by inappropriate activation of the gut mucosal immune system. As the only immunoglobulin G (IgG) subclass unable to activate the classical complement cascade, the role of IgG4 in IBD pathophysiology as an immunomodulator is controversial. This study aimed to determine the association of low, normal and high IgG4 levels with the outcomes of IBD patients.

Methods

This was a retrospective study of a multisite tertiary care center database evaluating patients with IBD who had an IgG4 level drawn between 2014 and 2021. Subjects were divided into low, normal, and high IgG4 level groups for evaluation of demographic and clinical indicators of IBD activity and severity.

Results

Of 284 patients with IBD, 22 had low (7.7%), 16 high (5.6%), and 246 (86.6%) normal IgG4 levels. There was no difference in IBD subtype, mean age, age at IBD diagnosis, or smoking between the 3 groups. There was no difference in number of hospitalizations (P=0.20), C-reactive protein levels, need for intestinal resection (P=0.85), or presence of primary sclerosing cholangitis (P=0.15), pancreatitis (P=0.70), or perianal disease (P=0.68) between the groups. Significantly more patients in the low IgG4 group had previous exposure to vedolizumab compared to the other groups and more patients in the low IgG4 group received vedolizumab (P=0.04), azathioprine (P=0.04) and prednisone (P=0.03) during the 5-year follow up.

Conclusion

In this study, a low serum IgG4 level was associated with higher rates of vedolizumab, azathioprine, and steroid use.

Primary sclerosing cholangitis (PSC) and inflammatory bowel disease (IBD): a condition exemplifying the crosstalk of the gut-liver axis

The close relationship between primary sclerosing cholangitis (PSC) and inflammatory bowel disease (IBD) provides a good opportunity to comprehend the gut-liver axis. The gut and the liver have reciprocal interactions, including how gut inflammation influences the liver through immune cells and the microbiota and how the microbiota in the gut modifies bile acids, which are produced and secreted from the liver. PSC-IBD shows distinct clinical findings from classical IBD. In addition, a distinct genetic predisposition and unique microbiota composition suggest that PSC-IBD is an independent disease entity. Understanding the pathogenesis of PSC-IBD helps to develop novel and effective therapeutic agents. Given the high risk of malignancies associated with PSC-IBD, it is critical to identify patients at high risk and implement appropriate surveillance and monitoring strategies. In this review, we provide an overview of PSC-IBD, which exemplifies the gut-liver axis.

The Impact of Concomitant Ulcerative Colitis on the Clinical Course in Patients with Primary Sclerosing Cholangitis: An Investigation Using a Nationwide Database in Japan

Introoduction

Primary sclerosing cholangitis (PSC) is a rare disease, especially in Asian countries. PSC often develops during ulcerative colitis (UC). Little is known about the severity of PSC in patients with UC. Thus, this study aimed to investigate the impact of concomitant UC on the clinical course of patients with PSC using a nationwide database in Japan.

Methods

We collected data on patients who were admitted for PSC using a nationwide database and divided eligible admissions according to concomitant UC (PSC-UC group vs. PSC-alone group). We conducted propensity score matching and compared the rates of liver transplantation, biliary drainage, and other clinical events between the two groups. We also conducted a multivariate analysis to identify the clinical factors that affect biliary drainage, cholangiocarcinoma, and liver transplantation.

Results

We enrolled 672 patients after propensity score matching. The rate of liver transplantation in the PSC-UC group was lower than that in the PSC-alone group (2.2 vs. 5.4%, p = 0.002), whereas the rate of biliary drainage did not differ between the two groups (38.1 vs. 33.8%, p = 0.10). On multivariate analysis, concomitant UC was identified as a clinical factor that decreased the risk of liver transplantation (odds ratio = 0.40, 95% confidence interval: 0.23-0.68, p = 0.0007).

Discussion

Concomitant UC in patients with PSC may decrease the risk of liver transplantation. The milder disease activity of PSC with UC is more likely compared to that of PSC without UC.

Role of intestinal flora in primary sclerosing cholangitis and its potential therapeutic value

Primary sclerosing cholangitis (PSC) is an autoimmune disease characterized by chronic cholestasis, a persistent inflammation of the bile ducts that leads to sclerotic occlusion and cholestasis. Gut microbes, consisting of microorganisms colonized in the human gut, play an important role in nutrient intake, metabolic homeostasis, immune regulation, and immune regulation; however, their presence might aid PSC development. Studies have found that gut-liver axis interactions also play an important role in the pathogenesis of PSC. Patients with PSC have considerably reduced intestinal flora diversity and increased abundance of potentially pathogenic bacteria. Dysbiosis of the intestinal flora leads to increased intestinal permeability, homing of intestinal lymphocytes, entry of bacteria and their associated metabolites, such as bile acids, into the liver, stimulation of hepatic immune activation, and promotion of PSC. Currently, PSC effective treatment is lacking. However, a number of studies have recently investigated the targeted modulation of gut microbes for the treatment of various liver diseases (alcoholic liver disease, metabolic fatty liver, cirrhosis, and autoimmune liver disease). In addition, antibiotics, fecal microbiota transplantation, and probiotics have been reported as successful PSC therapies as well as for the treatment of gut dysbiosis, suggesting their effectiveness for PSC treatment. Therefore, this review briefly summarizes the role of intestinal flora in PSC with the aim of providing new insights into PSC treatment.