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Thrombosis after liver transplantation substantially impairs graft‐ and patient survival. Inevitably, heritable disorders of coagulation originating in the donor liver are transmitted by transplantation. We hypothesized that genetic variants in donor thrombophilia genes are associated with increased risk of posttransplant thrombosis. We genotyped 775 donors for adult recipients and 310 donors for pediatric recipients transplanted between 1993 and 2018. We determined the association between known donor thrombophilia gene variants and recipient posttransplant thrombosis. In addition, we performed a genome‐wide association study (GWAS) and meta‐analyzed 1085 liver transplantations. In our donor cohort, known thrombosis risk loci were not associated with posttransplant thrombosis, suggesting that it is unnecessary to exclude liver donors based on thrombosis‐susceptible polymorphisms. By performing a meta‐GWAS from children and adults, we identified 280 variants in 55 loci at suggestive genetic significance threshold. Downstream prioritization strategies identified biologically plausible candidate genes, among which were AK4 (rs11208611‐T, p = 4.22 × 10−05) which encodes a protein that regulates cellular ATP levels and concurrent activation of AMPK and mTOR, and RGS5 (rs10917696‐C, p = 2.62 × 10−05) which is involved in vascular development. We provide evidence that common genetic variants in the donor, but not previously known thrombophilia‐related variants, are associated with increased risk of thrombosis after liver transplantation., A meta‐analysis of two genome‐wide association studies of adult and pediatric liver transplants identifies three common candidate risk loci in the donor, but not previously known thrombophilia‐related variants, were newly associated with increased risk of thrombosis after liver transplantation.

Organ transplantation is a life-saving treatment for patients with end-stage disease, but survival rates after transplantation vary considerably. There is now increasing evidence that the gut microbiome is linked to the survival of patients undergoing hematopoietic cell transplant, yet little is known about the role of the gut microbiome in solid organ transplantation. We analyzed 1370 fecal samples from 415 liver and 672 renal transplant recipients using shotgun metagenomic sequencing to assess microbial taxonomy, metabolic pathways, antibiotic resistance genes, and virulence factors. To quantify taxonomic and metabolic dysbiosis, we also analyzed 1183 age-, sex-, and body mass index–matched controls from the same population. In addition, a subset of 78 renal transplant recipients was followed longitudinally from pretransplantation to 24 months after transplantation. Our data showed that both liver and kidney transplant recipients suffered from gut dysbiosis, including lower microbial diversity, increased abundance of unhealthy microbial species, decreased abundance of important metabolic pathways, and increased prevalence and diversity of antibiotic resistance genes and virulence factors. These changes were found to persist up to 20 years after transplantation. Last, we demonstrated that the use of immunosuppressive drugs was associated with the observed dysbiosis and that the extent of dysbiosis was associated with increased mortality after transplantation. This study represents a step toward potential microbiome-targeted interventions that might influence the outcomes of recipients of solid organ transplantation.

Dysregulation of gut mucosal host–microbe interactions is a central feature of inflammatory bowel disease (IBD). To study tissue-specific interactions, we performed transcriptomic (RNA-seq) and microbial (16S-rRNA-seq) profiling of 696 intestinal biopsies derived from 353 patients with IBD and controls. Analysis of transcript-bacteria interactions identified six distinct groups of inflammation-related pathways that were associated with intestinal microbiota, findings we could partially validate in an independent cohort. An increased abundance of Bifidobacterium was associated with higher expression of genes involved in fatty acid metabolism, while Bacteroides was associated with increased metallothionein signaling. In fibrostenotic Crohn’s disease, a transcriptional network dominated by immunoregulatory genes associated with Lachnoclostridium bacteria in non-stenotic tissue. In patients using TNF-α-antagonists, a transcriptional network dominated by fatty acid metabolism genes associated with Ruminococcaceae. Mucosal microbiota composition was associated with enrichment of specific intestinal cell types. Overall, we identify multiple host–microbe interactions that may guide microbiota-directed precision medicine.

ObjectiveInflammatory bowel disease (IBD) is a multifactorial immune-mediated inflammatory disease of the intestine, comprising Crohn’s disease and ulcerative colitis. By characterising metabolites in faeces, combined with faecal metagenomics, host genetics and clinical characteristics, we aimed to unravel metabolic alterations in IBD.DesignWe measured 1684 different faecal metabolites and 8 short-chain and branched-chain fatty acids in stool samples of 424 patients with IBD and 255 non-IBD controls. Regression analyses were used to compare concentrations of metabolites between cases and controls and determine the relationship between metabolites and each participant’s lifestyle, clinical characteristics and gut microbiota composition. Moreover, genome-wide association analysis was conducted on faecal metabolite levels.ResultsWe identified over 300 molecules that were differentially abundant in the faeces of patients with IBD. The ratio between a sphingolipid and L-urobilin could discriminate between IBD and non-IBD samples (AUC=0.85). We found changes in the bile acid pool in patients with dysbiotic microbial communities and a strong association between faecal metabolome and gut microbiota. For example, the abundance ofRuminococcus gnavuswas positively associated with tryptamine levels. In addition, we found 158 associations between metabolites and dietary patterns, and polymorphisms nearNAT2strongly associated with coffee metabolism.ConclusionIn this large-scale analysis, we identified alterations in the metabolome of patients with IBD that are independent of commonly overlooked confounders such as diet and surgical history. Considering the influence of the microbiome on faecal metabolites, our results pave the way for future interventions targeting intestinal inflammation.

Background and Aims Crohn’s disease [CD] is characterised by chronic intestinal inflammation and dysbiosis in the gut. Riboflavin [vitamin B2] has anti-inflammatory, antioxidant and microbiome-modulatory properties. Here, we analysed the effect of riboflavin on oxidative stress, markers of inflammation, clinical symptoms, and faecal microbiome in patients with CD. Methods In this prospective clinical intervention study, patients received 100 mg riboflavin [DSM, Nutritional Products Ltd] daily for 3 weeks. Clinical disease activity [Harvey-Bradshaw Index: HBI], serum biomarkers of inflammation and redox status [plasma free thiols], and faecal microbiome taxonomical composition and functionality [fluorescent in situ hybridisation: FISH; and metagenomic shotgun sequencing: MGS], were analysed before and after riboflavin intervention. Results In total, 70 patients with CD with varying disease activity were included. Riboflavin supplementation significantly decreased serum levels of inflammatory markers. In patients with low faecal calprotectin [FC] levels, IL-2 decreased, and in patients with high FC levels, C-reactive protein [CRP] was reduced and free thiols significantly increased after supplementation. Moreover, HBI was significantly decreased by riboflavin supplementation. Riboflavin supplementation led to decreased Enterobacteriaceae in patients with low FC levels as determined by FISH; however, MGS analysis showed no effects on diversity, taxonomy, or metabolic pathways of the faecal microbiome. Conclusions Three weeks of riboflavin supplementation resulted in a reduction in systemic oxidative stress, mixed anti-inflammatory effects, and a reduction in clinical symptoms [HBI]. FISH analysis showed decreased Enterobacteriaceae in patients with CD with low FC levels, though this was not observed in MGS analysis. Our data demonstrate that riboflavin supplementation has a number of anti-inflammatory and anti-oxidant effects in CD.

More than 240 genetic risk loci have been associated with inflammatory bowel disease (IBD), but little is known about how they contribute to disease development in involved tissue. Here, we hypothesized that host genetic variation affects gene expression in an inflammation-dependent way, and investigated 299 snap-frozen intestinal biopsies from inflamed and non-inflamed mucosa from 171 IBD patients. RNA-sequencing was performed, and genotypes were determined using whole exome sequencing and genome wide genotyping. In total, 28,746 genes and 6,894,979 SNPs were included. Linear mixed models identified 8,881 independent intestinal cis-expression quantitative trait loci (cis-eQTLs) (FDR < 0.05) and interaction analysis revealed 190 inflammation-dependent intestinal cis-eQTLs (FDR < 0.05), including known IBD-risk genes and genes encoding immune-cell receptors and antibodies. The inflammation-dependent cis-eQTL SNPs (eSNPs) mainly interact with prevalence of immune cell types. Inflammation-dependent intestinal cis-eQTLs reveal genetic susceptibility under inflammatory conditions that can help identify the cell types involved in and the pathways underlying inflammation, knowledge that may guide future drug development and profile patients for precision medicine in IBD., Inflammatory bowel diseases are heterogeneous, and little is known about how underlying genetic variation can affect their development. Here, the authors report that intestinal inflammation modulates the effect of host genetics on the gut mucosal expression of 190 genes in the context of inflammatory bowel diseases.

Organ transplantation is a life-saving treatment for patients with end-stage disease, but survival post-transplantation varies considerably. There is now increasing evidence that the gut microbiome is linked to the survival of hematopoietic cell transplant patients, yet little is known about the role of the gut microbiome in solid organ transplantation. We analyzed 1,370 fecal samples from liver and renal transplant recipients using shotgun metagenomic sequencing to assess microbial taxonomy, metabolic pathways, antibiotic resistance genes and virulence factors. To quantify taxonomic and metabolic dysbiosis, we analyzed 1,183 age-, sex- and BMI-matched subjects from the same population. A subset of patients were also followed longitudinally from pre- to post-transplantation. Our data show that transplant recipients suffer from gut dysbiosis—including lower microbial diversity, increased abundance of unhealthy microbial species, decreased abundance of important metabolic pathways, and increased prevalence and diversity of antibiotic resistant genes and virulence factors—that persist up to 20 years post-transplantation. Finally, we demonstrate that the use of immunosuppressive drugs is significantly associated with the observed dysbiosis and that the extent of dysbiosis is associated with increased post-transplant mortality.

Background and Aims The human gastrointestinal tract harbours distinct microbial communities essential for health. Little is known about small intestinal communities, despite the small intestine playing a fundamental role in nutrient absorption and host-microbe immune homeostasis. We aimed to explore the small intestine microbial composition and metabolic potential, in the context of inflammatory bowel disease [IBD]. Methods Metagenomes derived from faecal samples and extensive phenotypes were collected from 57 individuals with an ileostomy or ileoanal pouch, and compared with 1178 general population and 478 IBD faecal metagenomes. Microbiome features were identified using MetaPhAn2 and HUMAnN2, and association analyses were performed using multivariate linear regression. Results Small intestinal samples had a significantly lower bacterial diversity, compared with the general population and, to a lesser extent, IBD samples. Comparing bacterial composition, small intestinal samples clustered furthest from general population samples and closest to IBD samples with intestinal resections. Veillonella atypica, Streptococcus salivarius, and Actinomyces graevenitzii were among the species significantly enriched in the small intestine. Predicted metabolic pathways in the small intestine are predominantly involved in simple carbohydrate and energy metabolism, but also suggest a higher pro-inflammatory potential. Conclusions We described the bacterial composition and metabolic potential of the small intestinal microbiota. The colonic microbiome of IBD patients, particularly with intestinal resections, showed resemblance to that of the small intestine. Moreover, several features characterising the small intestinal microbiome have been previously associated with IBD. These results highlight the importance of studying the small intestinal microbiota to gain new insight into disease pathogenesis.

The gut microbiome is associated with diverse diseases, but the universal signature of an (un)healthy microbiome remains elusive and there is a need to understand how genetics, exposome, lifestyle and diet shape the microbiome in health and disease. To fill this gap, we profiled bacterial composition, function, antibiotic resistance and virulence factors in the gut microbiomes of 8,208 Dutch individuals from a three-generational cohort comprising 2,756 families. We then correlated this to 241 host and environmental factors, including physical and mental health, medication use, diet, socioeconomic factors and childhood and current exposome. We identify that the microbiome is primarily shaped by environment and cohousing. Only ~13% of taxa are heritable, which are enriched with highly prevalent and health-associated bacteria. By identifying 2,856 associations between microbiome and health, we find that seemingly unrelated diseases share a common signature that is independent of comorbidities. Furthermore, we identify 7,519 associations between microbiome features and diet, socioeconomics and early life and current exposome, of which numerous early-life and current factors are particularly linked to the microbiome. Overall, this study provides a comprehensive overview of gut microbiome and the underlying impact of heritability and exposures that will facilitate future development of microbiome-targeted therapies.

Intestinal fibrosis is a common complication of inflammatory bowel disease. So far, there is no safe and effective drug for intestinal fibrosis. Pirfenidone is an anti-fibrotic compound available for the treatment of idiopathic pulmonary fibrosis. Here, we explored the anti-proliferative and anti-fibrotic properties of pirfenidone on primary human intestinal fibroblasts (p-hIFs). p-hIFs were cultured in the absence and presence of pirfenidone. Cell proliferation was measured by a real-time cell analyzer (xCELLigence) and BrdU incorporation. Cell motility was monitored by live cell imaging. Cytotoxicity and cell viability were analyzed by Sytox green, Caspase-3 and Water Soluble Tetrazolium Salt-1 (WST-1) assays. Gene expression of fibrosis markers was determined by quantitative reverse transcription PCR (RT-qPCR). The mammalian target of rapamycin (mTOR) signaling was analyzed by Western blotting and type I collagen protein expression additionally by immunofluorescence microscopy. Pirfenidone dose-dependently inhibited p-hIF proliferation and motility, without inducing cell death. Pirfenidone suppressed mRNA levels of genes that contribute to extracellular matrix production, as well as basal and TGF-&beta, 1-induced collagen I protein production, which was associated with inhibition of the rapamycin-sensitive mTOR/p70S6K pathway in p-hIFs. Thus, pirfenidone inhibits the proliferation of intestinal fibroblasts and suppresses collagen I production through the TGF-&beta, 1/mTOR/p70S6K signaling pathway, which might be a novel and safe anti-fibrotic strategy to treat intestinal fibrosis.

Background Mucosal healing is the ultimate treatment goal in inflammatory bowel disease (IBD). Endoscopic examination is the gold standard to determine disease activity in IBD, as routine activity measures, such as C-reactive protein (CRP), faecal calprotectin and clinical disease indices are inconsistent in representing luminal disease activity. Therefore, there is a great need for non-invasive biomarkers to assess mucosal inflammation. The aim of this study was to build an accurate prediction model of endoscopic disease activity in patients with quiescent and active IBD, based on a combination of serum inflammatory biomarkers. Methods Serum concentrations of 10 inflammatory biomarkers were analysed in 118 IBD patients (64 Crohn’s disease (CD), 54 ulcerative colitis (UC)) prior to biological treatment and 20 healthy controls. In 71 IBD patients, endoscopic disease activity was assessed by the Simple Endoscopic Score for CD (SES-CD) and Mayo endoscopic subscore for UC. Nonparametric ROC estimation with bootstrap inference was used to establish the best combination of inflammatory biomarkers predicting endoscopic disease activity. Results Six (6) inflammatory biomarkers (serum amyloid A (SAA), Eotaxin-1, IL-6, IL-8, IL-17A and TNF-α) all individually showed better prediction of IBD disease activity compared with routine measures (CRP, faecal calprotectin and HBI/SCCAI scores). The best combination of predictive inflammatory biomarkers consisted of serum SAA, IL-6, IL-8 and Eotaxin-1, showing an optimism-adjusted area under the ROC curve of 0.84 (95% CI: 0.73–0.94, P < 0.0001), which predicted significantly better (P = 0.002) than serum CRP levels with an AuROC of 0.57 (95% CI: 0.43–0.72, P = 0.32). The resulting combined calculated probability had a maximum sensitivity of 90.7% and specificity of 68.4% in correctly classifying IBD patients into the low and high endoscopic disease activity category (Youden’s J statistic = 0.58). Conclusions The combination of SAA, IL-6, IL-8 and Eotaxin-1 is superior over routine measures in predicting endoscopic disease activity in IBD. Serum inflammatory biomarkers are valuable tools for monitoring intestinal inflammation and guiding therapeutic decisions.