Thijmen Visseren

Background/Objectives: Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease frequently requiring liver transplantation (LTx). The gut–liver axis, host genetics, and microbial dysbiosis are thought to contribute to disease progression and post-transplant outcomes. The FUT2 rs601338 polymorphism influences mucosal fucosylation, host–microbial interactions, and susceptibility to infection. This study aimed to investigate the association between FUT2 genotype, colonic mucosal microbiome composition, post-transplant bacteremia, and all-cause mortality in a retrospective single-center PSC cohort. Methods: This retrospective cohort study included PSC patients who underwent LTx at Erasmus MC University Medical Center (Rotterdam, The Netherlands) between 1987 and 2015. Pre-transplant archival formalin-fixed paraffin-embedded (FFPE) colonic biopsy specimens were available for microbiome analysis. Of 169 transplanted patients, FFPE tissue was available for 98 individuals, and FUT2 rs601338 genotyping was successfully performed in 87 patients. Patients were classified as FUT2 non-secretors (AA, n = 28) and secretors (GA/GG, n = 59). Post-transplant bacteremia was assessed based on clinically indicated blood cultures during follow-up. Colonic mucosal microbiome composition was analyzed using 16S rRNA gene sequencing. Results: FUT2 non-secretors showed a distinct colonic mucosal microbiome profile compared with secretors, characterized by differential abundance of selected taxa within Proteobacteria, Firmicutes, and Bacteroidetes. Post-transplant bacteremia occurred in 30 patients and was more frequent among non-secretors (43%) compared with secretors (15%). Both FUT2 non-secretor status and post-transplant bacteremia were associated with reduced all-cause post-transplant survival in Kaplan–Meier analysis and remained associated with mortality in multivariable regression models. Specific microbial taxa were also showed associations with bacteremia, mortality, and established prognostic scores, including the Amsterdam–Oxford Model and Mayo Risk Score. Conclusions: FUT2 genotype is associated with alterations in colonic mucosal microbiome composition, post-transplant bacteremia, and all-cause mortality in PSC patients undergoing liver transplantation. These findings suggest a potential interplay between host genetics, intestinal microbiota, and infectious complications after transplantation. Given the retrospective design, limited sample size, and use of archival FFPE tissue, all findings should be interpreted as exploratory and hypothesis-generating. Prospective multicenter studies using standardized sampling and high-resolution metagenomic approaches are warranted for validation.

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Background: Formalin-fixed paraffin embedded (FFPE) tissues may provide an exciting resource to study microbial associations in human disease, but the use of these low biomass specimens remains challenging. We aimed to reduce unintentional bacterial interference in molecular analysis of FFPE tissues and investigated the feasibility of conducting quantitative polymerase chain reaction (qPCR) and 16S rRNA amplicon sequencing using 14 colorectal cancer, 14 normal adjacent and 13 healthy control tissues. Results: Bacterial contaminants from the laboratory environment and the co-extraction of human DNA can affect bacterial analysis. The application of undiluted template improves bacterial DNA amplification, allowing the detection of specific bacterial markers (Escherichia coli and Faecalibacterium prausnitzii) by qPCR. Nested and non-nested PCR-based 16S rRNA amplicon sequencing approaches were employed, showing that bacterial communities of tissues and paired paraffin controls cluster separately at genus level on weighted Unifrac in both non-nested (R2 = 0.045; Pr(> F) = 0.053) and nested (R2 = 0.299; Pr(> F) = 0.001) PCR datasets. Nevertheless, considerable overlap of bacterial genera within tissues was seen with paraffin, DNA extraction negatives (non-nested PCR) or PCR negatives (nested PCR). Following mathematical decontamination, no differences in α- and β diversity were found between tumor, normal adjacent and control tissues. Conclusions: Bacterial marker analysis by qPCR seems feasible using non-normalized template, but 16S rRNA amplicon sequencing remains challenging. Critical evaluation of laboratory procedures and incorporation of positive and negative controls for bacterial analysis of FFPE tissues are essential for quality control and to account for bacterial contaminants.

Background Liver transplantation for primary sclerosing cholangitis (PSC) can be complicated by recurrence of PSC (rPSC). This may compromise graft survival but the effect on patient survival is less clear. We investigated the effect of post-transplant rPSC on graft and patient survival in a large European cohort. Methods Registry data from the European Liver Transplant Registry regarding all first transplants for PSC between 1980 and 2015 were supplemented with detailed data on rPSC from 48 out of 138 contributing transplant centres, involving 1,549 patients. Bayesian proportional hazards models were used to investigate the impact of rPSC and other covariates on patient and graft survival. Results Recurrence of PSC was diagnosed in 259 patients (16.7%) after a median follow-up of 5.0 years (quantile 2.5%-97.5%: 0.4–18.5), with a significant negative impact on both graft (HR 6.7; 95% CI 4.9–9.1) and patient survival (HR 2.3; 95% CI 1.5–3.3). Patients with rPSC underwent significantly more re-transplants than those without rPSC (OR 3.6, 95% CI 2.7–4.8). Conclusions PSC recurrence has a negative impact on both graft and patient survival, independent of transplant-related covariates. Recurrence of PSC leads to higher number of re-transplantations and a 33% decrease in 10-year graft survival.

Primary sclerosing cholangitis (PSC) is a common indication for liver transplantation (LT). Up to 25% of patients experience recurrence of PSC (rPSC) after LT, which is associated with significant morbidity and mortality. To date, it is not possible to predict which patients are at risk for rPSC. The aetiology of PSC is complex and is speculated to involve translocation of intestinal bacteria to the liver, because of its frequent co‐occurrence with inflammatory bowel diseases (IBD). Here, we investigate whether the mucosal intestinal microbiome of PSC patients (n=97) at time of first LT can identify those patients who will develop rPSC. 16S gene sequencing of bacterial DNA isolated from formalin fixed paraffin embedded biopsies showed that PSC patients with Crohn’s disease (n=15) have a reduced microbial diversity and that inflammation of the mucosa is associated with beta‐diversity changes and feature differences. No differences in alpha‐ or beta‐diversity were observed between patients with rPSC (n=14) and without rPSC (n=83). However, many over‐represented bacterial features were detected in patients with rPSC, while surprisingly, those without recurrence of disease were characterized by an increased presence of the Gammaproteobacteria Shigella . This pilot study warrants further investigation into bacterial differences between rPSC and non‐rPSC patients.

Sepsis has a high mortality. Early recognition and timely treatment are essential for patient survival. The aim of this study is to examine the factors that influence the knowledge and recognition of systemic inflammatory response syndrome (SIRS) criteria and sepsis by emergency department (ED) nurses. A prospective, multi-center study including 216 ED nurses from 11 hospitals and academic medical centers in The Netherlands was conducted in 2013. A validated questionnaire was used to evaluate ED nurses’ knowledge about SIRS and sepsis. Questions about demographic characteristics were also included, to investigate factors that may contribute to the knowledge about SIRS and sepsis. The mean total score was 15.9 points, with a maximum possible score of 29 points. ED nurses employed at hospitals with a level 3 intensive care unit (ICU) scored significantly higher than their colleagues employed at hospitals with a level 1 or 2 ICU. Recently completed education in sepsis was associated with a higher score. The employees in low ICU level hospitals who reported recent education did not score significantly lower than their ICU level 3 colleagues. ED nurses over the age of 50 scored significantly lower than their younger colleagues. The knowledge of ED nurses concerning SIRS and sepsis rises proportionally with the level of ICU in hospitals. Recent education in sepsis raises knowledge level as well. We recommend that when there is a low exposure rate to SIRS and sepsis, more emphasis should be placed on regular education.