Age-dependent impact of the major common genetic risk factor for COVID-19 on severity and mortality

BACKGROUND

There is considerable variability in COVID-19 outcomes amongst younger adults-and some of this variation may be due to genetic predisposition.

METHODS

We combined individual level data from 13,888 COVID-19 patients (N=7,185 hospitalized) from 17 cohorts in nine countries to assess the association of the major common COVID-19 genetic risk factor (chromosome 3 locus tagged by rs10490770) with mortality, COVID-19-related complications and laboratory values. We next performed meta-analyses using FinnGen and the Columbia University COVID-19 Biobank.

RESULTS

We found that rs10490770 risk allele carriers experienced an increased risk of all-cause mortality (HR 1.4, 95%CI 1.2-1.7). Risk allele carriers had increased odds of several COVID-19 complications: severe respiratory failure (OR 2.1, 95%CI 1.6-2.6), venous thromboembolism (OR 1.7, 95%CI 1.2-2.4), and hepatic injury (OR 1.5, 95%CI 1.2-2.0). Risk allele carriers ≤60 years had higher odds of death or severe respiratory failure (OR 2.7, 95%CI 1.8-3.9) compared to those >60 years (OR 1.5, 95%CI 1.2-1.8, interaction-p=0.038). Amongst individuals ≤60 years who died or experienced severe respiratory failure, 32.3% were risk variant carriers, compared to 13.9% of those not experiencing these outcomes. The genetic risk improved the prediction of death or severe respiratory failure similarly to, or better than, most established clinical risk factors.

CONCLUSIONS

The major common COVID-19 genetic risk factor is associated with increased risks of morbidity and mortality, which are more pronounced amongst individuals ≤60 years. The effect was similar in magnitude and more common than most established clinical risk factors, suggesting potential implications for future clinical risk management.

Gut microbiota depletion exacerbates cholestatic liver injury via loss of FXR signalling

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease of unknown aetiology for which there are no approved therapeutic options. Patients with PSC display changes in gut microbiota and in bile acid (BA) composition; however, the contribution of these alterations to disease pathogenesis remains controversial. Here we identify a role for microbiota-dependent changes in BA synthesis that modulates PSC pathophysiology. In a genetic mouse model of PSC, we show that loss of microbiota-mediated negative feedback control of BA synthesis results in increased hepatic BA concentrations, disruption of bile duct barrier function and, consequently, fatal liver injury. We further show that these changes are dependent on decreased BA signalling to the farnesoid X receptor, which modulates the activity of the rate-limiting enzyme in BA synthesis, CYP7A1. Moreover, patients with advanced stages of PSC show suppressed BA synthesis as measured by serum C4 levels, which is associated with poor disease prognosis. Our preclinical data highlight the microbiota-dependent dynamics of BA metabolism in cholestatic liver disease, which could be important for future therapies targeting BA and gut microbiome interactions, and identify C4 as a potential biomarker to functionally stratify patients with PSC and predict disease outcomes.

Downregulation of TGR5 (GPBAR1) in biliary epithelial cells contributes to the pathogenesis of sclerosing cholangitis

BACKGROUND & AIMS

Primary sclerosing cholangitis (PSC) is characterized by chronic inflammation and progressive fibrosis of the biliary tree. The bile acid receptor TGR5 (GPBAR1) is found on biliary epithelial cells (BECs), where it promotes secretion, proliferation and tight junction integrity. Thus, we speculated that changes in TGR5-expression in BECs may contribute to PSC pathogenesis.

METHODS

TGR5-expression and -localization were analyzed in PSC livers and liver tissue, isolated bile ducts and BECs from Abcb4^-/-, Abcb4^-/-/Tgr5^Tg and ursodeoxycholic acid (UDCA)- or 24-norursodeoxycholic acid (norUDCA)-fed Abcb4^-/- mice. The effects of IL8/IL8 homologues on TGR5 mRNA and protein levels were studied. BEC gene expression was analyzed by single-cell transcriptomics (scRNA-seq) from distinct mouse models.

RESULTS

TGR5 mRNA expression and immunofluorescence staining intensity were reduced in BECs of PSC and Abcb4^-/- livers, in Abcb4^-/- extrahepatic bile ducts, but not in intrahepatic macrophages. No changes in TGR5 BEC fluorescence intensity were detected in liver tissue of other liver diseases, including primary biliary cholangitis. Incubation of BECs with IL8/IL8 homologues, but not with other cytokines, reduced TGR5 mRNA and protein levels. BECs from Abcb4^-/- mice had lower levels of phosphorylated Erk and higher expression levels of Icam1, Vcam1 and Tgfβ2. Overexpression of Tgr5 abolished the activated inflammatory phenotype characteristic of Abcb4^-/- BECs. NorUDCA-feeding restored TGR5-expression levels in BECs in Abcb4^-/- livers.

CONCLUSIONS

Reduced TGR5 levels in BECs from patients with PSC and Abcb4^-/- mice promote development of a reactive BEC phenotype, aggravate biliary injury and thus contribute to the pathogenesis of sclerosing cholangitis. Restoration of biliary TGR5-expression levels represents a previously unknown mechanism of action of norUDCA.

LAY SUMMARY

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease-associated with progressive inflammation of the bile duct, leading to fibrosis and end-stage liver disease. Bile acid (BA) toxicity may contribute to the development and disease progression of PSC. TGR5 is a membrane-bound receptor for BAs, which is found on bile ducts and protects bile ducts from BA toxicity. In this study, we show that TGR5 levels were reduced in bile ducts from PSC livers and in bile ducts from a genetic mouse model of PSC. Our investigations indicate that lower levels of TGR5 in bile ducts may contribute to PSC development and progression. Furthermore, treatment with norUDCA, a drug currently being tested in a phase III trial for PSC, restored TGR5 levels in biliary epithelial cells.

Rifaximin or Saccharomyces boulardii in heart failure with reduced ejection fraction: Results from the randomized GutHeart trial

Background

The gut microbiota represents a potential treatment target in heart failure (HF) through microbial metabolites such as trimethylamine N-oxide (TMAO) and systemic inflammation. Treatment with the probiotic yeast Saccharomyces boulardii have been suggested to improve left ventricular ejection fraction (LVEF).

Methods

In a multicentre, prospective randomized open label, blinded end-point trial, we randomized patients with LVEF <40% and New York Heart Association functional class II or III, despite optimal medical therapy, to treatment (1:1:1) with the probiotic yeast Saccharomyces boulardii, the antibiotic rifaximin, or standard of care (SoC) only. The primary endpoint, the baseline-adjusted LVEF at three months, was assessed in an intention-to-treat analysis.

Findings

We enrolled a total of 151 patients. After three months’ treatment, the LVEF did not differ significantly between the SoC arm and the rifaximin arm (mean difference was -1•2 percentage points; 95% CI -3•2 - 0•7; p=0•22) or between the SoC arm and the Saccharomyces boulardii arm (mean difference -0•2 percentage points; 95% CI -2•2 - 1•9; p=0•87). We observed no significant between-group differences in changes in microbiota diversity, TMAO, or C-reactive protein.

Interpretation

Three months’ treatment with Saccharomyces boulardii or rifaximin on top of SoC had no significant effect on LVEF, microbiota diversity, or the measured biomarkers in our population with HF.

Funding

The trial was funded by the Norwegian Association for Public Health, the Blix foundation, Stein Erik Hagen's Foundation for Clinical Heart Research, Ada og Hagbart Waages humanitære og veldedige stiftelse, Alfasigma, and Biocodex.

A biliary immune landscape map of primary sclerosing cholangitis reveals a dominant network of neutrophils and tissue-resident T cells

The human biliary system, a mucosal barrier tissue connecting the liver and intestine, is an organ often affected by serious inflammatory and malignant diseases. Although these diseases are linked to immunological processes, the biliary system represents an unexplored immunological niche. By combining endoscopy-guided sampling of the biliary tree with a high-dimensional analysis approach, comprehensive mapping of the human biliary immunological landscape in patients with primary sclerosing cholangitis (PSC), a severe biliary inflammatory disease, was conducted. Major differences in immune cell composition in bile ducts compared to blood were revealed. Furthermore, biliary inflammation in patients with PSC was characterized by high presence of neutrophils and T cells as compared to control individuals without PSC. The biliary T cells displayed a CD103⁺CD69⁺ effector memory phenotype, a combined gut and liver homing profile, and produced interleukin-17 (IL-17) and IL-22. Biliary neutrophil infiltration in PSC associated with CXCL8, possibly produced by resident T cells, and CXCL16 was linked to the enrichment of T cells. This study uncovers the immunological niche of human bile ducts, defines a local immune network between neutrophils and biliary-resident T cells in PSC, and provides a resource for future studies of the immune responses in biliary disorders.

Associations of neopterin and kynurenine-tryptophan ratio with survival in primary sclerosing cholangitis

BACKGROUND AND AIMS

Biomarkers of inflammation may be of clinical utility in primary sclerosing cholangitis (PSC). We aimed to investigate the interferon gamma-related biomarkers neopterin and kynurenine-tryptophanratio (KT-ratio) in PSC.

METHODS

Circulating neopterin, tryptophan and kynurenine were measured with LC-MS/MS in multiple cross-sectional cohorts comprising in total of 524 PSC patients and 100 healthy controls from Norway, Germany and Sweden.

RESULTS

Neopterin and KT-ratio were significantly increased in PSC patients compared with controls in both a discovery and a validation cohort from Norway. Furthermore, high neopterin and KT-ratio levels were associated with a shorter transplantation-free survival in the PSC patients in the Norwegian discovery cohort and the German validation cohort. However, in the validation PSC cohort from Sweden, no relationship between neopterin and KT-ratio and liver transplantation-free survival was observed. The correlations between neopterin and KT-ratio were moderate to strong and similar in all cohorts (rho 0.50-0.67). Neopterin and KT-ratio also correlated with C-reactive protein (rho 0.17-0.63) and revised Mayo risk score (rho 0.23-0.42) in all cohorts.

CONCLUSIONS

Neopterin and KT-ratio were elevated in PSC and associated with liver transplantation-free survival in two independent PSC cohorts, highlighting a possible role of interferon gamma-driven inflammation in the pathogenesis. However, the lack of association with survival in one of the cohorts reduces the potential clinical value of neopterin and KT-ratioas biomarkers and highlights the need to validate new biomarkers in PSC in multiple cohorts.

Altered Gut Microbial Metabolism of Essential Nutrients in Primary Sclerosing Cholangitis

BACKGROUND & AIMS

To influence host and disease phenotype, compositional microbiome changes, which have been demonstrated in patients with primary sclerosing cholangitis (PSC), must be accompanied by functional changes. We therefore aimed to characterize the genetic potential of the gut microbiome in patients with PSC compared with healthy controls (HCs) and patients with inflammatory bowel disease (IBD).

METHODS

Fecal DNA from 2 cohorts (1 Norwegian and 1 German), in total comprising 136 patients with PSC (58% with IBD), 158 HCs, and 93 patients with IBD without PSC, were subjected to metagenomic shotgun sequencing, generating 17 billion paired-end sequences, which were processed using HUMAnN2 and MetaPhlAn2, and analyzed using generalized linear models and random effects meta-analyses.

RESULTS

Patients with PSC had fewer microbial genes compared with HCs (P < .0001). Compared with HCs, patients with PSC showed enrichment and increased prevalence of Clostridium species and a depletion of, for example, Eubacterium spp and Ruminococcus obeum. Patients with PSC showed marked differences in the abundance of genes related to vitamin B6 synthesis and branched-chain amino acid synthesis (Q_fdr < .05). Targeted metabolomics of plasma from an independent set of patients with PSC and controls found reduced concentrations of vitamin B6 and branched-chain amino acids in PSC (P < .0001), which strongly associated with reduced liver transplantation-free survival (log-rank P < .001). No taxonomic or functional differences were detected between patients with PSC with and without IBD.

CONCLUSIONS

The gut microbiome in patients with PSC exhibits large functional differences compared with that in HCs, including microbial metabolism of essential nutrients. Alterations in related circulating metabolites associated with disease course, suggesting that microbial functions may be relevant for the disease process in PSC.

Age-dependent impact of the major common genetic risk factor for COVID-19 on severity and mortality

BACKGROUND

There is considerable variability in COVID-19 outcomes amongst younger adults-and some of this variation may be due to genetic predisposition. We characterized the clinical implications of the major genetic risk factor for COVID-19 severity, and its age-dependent effect, using individual-level data in a large international multi-centre consortium.

METHOD

The major common COVID-19 genetic risk factor is a chromosome 3 locus, tagged by the marker rs10490770. We combined individual level data for 13,424 COVID-19 positive patients (N=6,689 hospitalized) from 17 cohorts in nine countries to assess the association of this genetic marker with mortality, COVID-19-related complications and laboratory values. We next examined if the magnitude of these associations varied by age and were independent from known clinical COVID-19 risk factors.

FINDINGS

We found that rs10490770 risk allele carriers experienced an increased risk of all-cause mortality (hazard ratio [HR] 1·4, 95% confidence interval [CI] 1·2-1·6) and COVID-19 related mortality (HR 1·5, 95%CI 1·3-1·8). Risk allele carriers had increased odds of several COVID-19 complications: severe respiratory failure (odds ratio [OR] 2·0, 95%CI 1·6-2·6), venous thromboembolism (OR 1·7, 95%CI 1·2-2·4), and hepatic injury (OR 1·6, 95%CI 1·2-2·0). Risk allele carriers ≤ 60 years had higher odds of death or severe respiratory failure (OR 2·6, 95%CI 1·8-3·9) compared to those > 60 years OR 1·5 (95%CI 1·3-1·9, interaction p-value=0·04). Amongst individuals ≤ 60 years who died or experienced severe respiratory COVID-19 outcome, we found that 31·8% (95%CI 27·6-36·2) were risk variant carriers, compared to 13·9% (95%CI 12·6-15·2%) of those not experiencing these outcomes. Prediction of death or severe respiratory failure among those ≤ 60 years improved when including the risk allele (AUC 0·82 vs 0·84, p=0·016) and the prediction ability of rs10490770 risk allele was similar to, or better than, most established clinical risk factors.

INTERPRETATION

The major common COVID-19 risk locus on chromosome 3 is associated with increased risks of morbidity and mortality-and these are more pronounced amongst individuals ≤ 60 years. The effect on COVID-19 severity was similar to, or larger than most established risk factors, suggesting potential implications for clinical risk management.

FUNDING

Funding was obtained by each of the participating cohorts individually.

Circulating Macrophage Activation Markers Predict Transplant-Free Survival in Patients With Primary Sclerosing Cholangitis

INTRODUCTION

Primary sclerosing cholangitis (PSC) is a progressive liver disease characterized by bile duct inflammation and fibrosis. The role of macrophages in PSC development and progression is less studied. Macrophage activation markers soluble (s)CD163 and mannose receptor (sMR) are associated with disease severity and outcome in other liver diseases, but not previously investigated in PSC. We evaluated sCD163 and sMR regarding disease severity and prognosis in patients with PSC.

METHODS

We investigated 2 independent PSC cohorts from Oslo (n = 138) and Helsinki (n = 159) and analyzed blood sCD163 and sMR levels. The Mayo score, Enhanced Liver Fibrosis Test, and Amsterdam-Oxford model were assessed for comparison.

RESULTS

Median (interquartile range) sCD163 was 3.32 (2.27-5.60) and 1.96 (1.47-2.70) mg/L in the Oslo and Helsinki cohorts, respectively, reflecting differences in disease severity between cohorts. Median sMR was similar in both cohorts, 0.28 (0.22-0.44) and 0.28 mg/L (0.20-0.36), respectively. In both cohorts, sCD163 and sMR levels raised with increasing disease severity (liver enzymes, Mayo score, and enhanced liver fibrosis test). Patients with high baseline levels of sCD163 had shorter transplant-free survival than patients with low baseline levels. Furthermore, sCD163 was associated with transplant-free survival in univariate cox-regression analyses. Both sCD163 and sMR performed better in the Oslo cohort of more severely diseased patients than those in the Helsinki cohort of more mildly diseased patients.

DISCUSSION

Macrophage activation markers are elevated according to disease severity suggesting an important role of macrophages in PSC. Furthermore, sCD163 was identified as a prognostic marker and predictor of transplant-free survival in PSC (see Visual Abstract, Supplementary Digital Content 4, http://links.lww.com/CTG/A516).

Inflammatory Bowel Disease-associated GP2 Autoantibodies Inhibit Mucosal Immune Response to Adherent-invasive Bacteria

Adherent-invasive Escherichia coli have been suggested to play a pivotal role within the pathophysiology of inflammatory bowel disease (IBD). Autoantibodies against distinct splicing variants of glycoprotein 2 (GP2), an intestinal receptor of the bacterial adhesin FimH, frequently occur in IBD patients. Hence, we aimed to functionally characterize GP2-directed autoantibodies as a putative part of IBD's pathophysiology. Ex vivo, GP2-splicing variant 4 (GP2#4) but not variant 2 was expressed on intestinal M or L cells with elevated expression patterns in IBD patients. The GP2#4 expression was induced in vitro by tumor necrosis factor (TNF)-α. The IBD-associated GP2 autoantibodies inhibited FimH binding to GP2#4 and were decreased in anti-TNFα-treated Crohn's disease patients with ileocolonic disease manifestation. In vivo, mice immunized against GP2 before infection with adherent-invasive bacteria displayed exacerbated intestinal inflammation. In summary, autoimmunity against intestinal expressed GP2#4 results in enhanced attachment of flagellated bacteria to the intestinal epithelium and thereby may drive IBD's pathophysiology.

Lipid antigens in bile from patients with chronic liver diseases activate natural killer T cells

Natural killer T (NKT) cells are an abundant subset of liver lymphocytes activated by lipid antigens presented on CD1d molecules that are expressed by cholangiocytes. We aimed to determine if bile from patients with chronic liver diseases contains antigenic lipids that can activate NKT cells. Using murine invariant (24.7, 24.8 and DN32.D3) and non-invariant (14S.6, 14S.7 and 14S.10) NKT hybridomas we investigated the presence of lipid antigens in bile collected from the gallbladder of patients undergoing liver transplantation due to end-stage liver disease. Biliary microbiota profiles were generated using 16S rRNA amplicon sequencing. We found that the patient bile samples contain antigens that activate both invariant and non-invariant NKT hybridomas (24.7, 24.8, DN32.D3, 14S.6, 14S.7 and 14S.10), as demonstrated by activation of at least one hybridoma by eight of 10 bile samples. Activation at high dilutions suggests that some antigens are highly potent. We used the non-invariant NKT hybridoma 14S.6 to screen 21 additional patient bile samples for NKT-reactivity and demonstrated that 12 of 21 bile samples resulted in activation, three of which gave a strong activation. Four of 12 activating bile samples contained microbial DNA. Our results reveal an immunological pathway that could be of critical importance in biliary immunology.

Genomewide Association Study of Severe Covid-19 with Respiratory Failure

BACKGROUND

There is considerable variation in disease behavior among patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (Covid-19). Genomewide association analysis may allow for the identification of potential genetic factors involved in the development of Covid-19.

METHODS

We conducted a genomewide association study involving 1980 patients with Covid-19 and severe disease (defined as respiratory failure) at seven hospitals in the Italian and Spanish epicenters of the SARS-CoV-2 pandemic in Europe. After quality control and the exclusion of population outliers, 835 patients and 1255 control participants from Italy and 775 patients and 950 control participants from Spain were included in the final analysis. In total, we analyzed 8,582,968 single-nucleotide polymorphisms and conducted a meta-analysis of the two case-control panels.

RESULTS

We detected cross-replicating associations with rs11385942 at locus 3p21.31 and with rs657152 at locus 9q34.2, which were significant at the genomewide level (P<5×10-8) in the meta-analysis of the two case-control panels (odds ratio, 1.77; 95% confidence interval [CI], 1.48 to 2.11; P = 1.15×10-10; and odds ratio, 1.32; 95% CI, 1.20 to 1.47; P = 4.95×10-8, respectively). At locus 3p21.31, the association signal spanned the genes SLC6A20, LZTFL1, CCR9, FYCO1, CXCR6 and XCR1. The association signal at locus 9q34.2 coincided with the ABO blood group locus; in this cohort, a blood-group-specific analysis showed a higher risk in blood group A than in other blood groups (odds ratio, 1.45; 95% CI, 1.20 to 1.75; P = 1.48×10-4) and a protective effect in blood group O as compared with other blood groups (odds ratio, 0.65; 95% CI, 0.53 to 0.79; P = 1.06×10-5).

CONCLUSIONS

We identified a 3p21.31 gene cluster as a genetic susceptibility locus in patients with Covid-19 with respiratory failure and confirmed a potential involvement of the ABO blood-group system. (Funded by Stein Erik Hagen and others.).

Gut Microbiota-Dependent Trimethylamine N-Oxide Associates With Inflammation in Common Variable Immunodeficiency

A substantial proportion of patients with common variable immunodeficiency (CVID) have inflammatory and autoimmune complications of unknown etiology. We have previously shown that systemic inflammation in CVID correlates with their gut microbial dysbiosis. The gut microbiota dependent metabolite trimethylamine N-oxide (TMAO) has been linked to several metabolic and inflammatory disorders, but has hitherto not been investigated in relation to CVID. We hypothesized that TMAO is involved in systemic inflammation in CVID. To explore this, we measured plasma concentrations of TMAO, inflammatory markers, and lipopolysaccharide (LPS) in 104 CVID patients and 30 controls. Gut microbiota profiles and the bacterial genes CutC and CntA, which encode enzymes that can convert dietary metabolites to trimethylamine in the colon, were examined in fecal samples from 40 CVID patients and 86 controls. Furthermore, a food frequency questionnaire and the effect of oral antibiotic rifaximin on plasma TMAO concentrations were explored in these 40 patients. We found CVID patients to have higher plasma concentrations of TMAO than controls (TMAO 5.0 [2.9-8.6] vs. 3.2 [2.2-6.3], p = 0.022, median with IQR). The TMAO concentration correlated positively with tumor necrosis factor (p = 0.008, rho = 0.26), interleukin-12 (p = 0.012, rho = 0.25) and LPS (p = 0.034, rho = 0.21). Dietary intake of meat (p = 0.678), fish (p = 0.715), egg (p = 0.138), dairy products (p = 0.284), and fiber (p = 0.767) did not significantly impact on the TMAO concentrations in plasma, nor did a 2-week course of the oral antibiotic rifaximin (p = 0.975). However, plasma TMAO concentrations correlated positively with gut microbial abundance of Gammaproteobacteria (p = 0.021, rho = 0.36). Bacterial gene CntA was present in significantly more CVID samples (75%) than controls (53%), p = 0.020, potentially related to the increased abundance of Gammaproteobacteria in these samples. The current study demonstrates that elevated TMAO concentrations are associated with systemic inflammation and increased gut microbial abundance of Gammaproteobacteria in CVID patients, suggesting that TMAO could be a link between gut microbial dysbiosis and systemic inflammation. Gut microbiota composition could thus be a potential therapeutic target to reduce systemic inflammation in CVID.

Alterations of the bile microbiome in primary sclerosing cholangitis

BACKGROUND

Patients with primary sclerosing cholangitis (PSC) display an altered colonic microbiome compared with healthy controls. However, little is known on the bile duct microbiome and its interplay with bile acid metabolism in PSC.

METHODS

Patients with PSC (n=43) and controls without sclerosing cholangitis (n=22) requiring endoscopic retrograde cholangiography were included prospectively. Leading indications in controls were sporadic choledocholithiasis and papillary adenoma. A total of 260 biospecimens were collected from the oral cavity, duodenal fluid and mucosa and ductal bile. Microbiomes of the upper alimentary tract and ductal bile were profiled by sequencing the 16S-rRNA-encoding gene (V1-V2). Bile fluid bile acid composition was measured by high-performance liquid chromatography mass spectrometry and validated in an external cohort (n=20).

RESULTS

The bile fluid harboured a diverse microbiome that was distinct from the oral cavity, the duodenal fluid and duodenal mucosa communities. The upper alimentary tract microbiome differed between PSC patients and controls. However, the strongest differences between PSC patients and controls were observed in the ductal bile fluid, including reduced biodiversity (Shannon entropy, p=0.0127) and increase of pathogen Enterococcus faecalis (FDR=4.18×10^-5) in PSC. Enterococcus abundance in ductal bile was strongly correlated with concentration of the noxious secondary bile acid taurolithocholic acid (r=0.60, p=0.0021).

CONCLUSION

PSC is characterised by an altered microbiome of the upper alimentary tract and bile ducts. Biliary dysbiosis is linked with increased concentrations of the proinflammatory and potentially cancerogenic agent taurolithocholic acid.

Low fibre intake is associated with gut microbiota alterations in chronic heart failure

AIMS

Recent reports have suggested that patients with heart failure (HF) have an altered gut microbiota composition; however, associations with diet remain largely uninvestigated. We aimed to explore differences in the gut microbiota between patients with HF with reduced ejection fraction and healthy controls, focusing on associations with diet and disease severity.

METHODS AND RESULTS

The microbiota composition of two cross-sectional cohorts (discovery, n = 40 and validation, n = 44) of patients with systolic HF and healthy controls (n = 266) was characterized by sequencing of the bacterial 16S rRNA gene. The overall microbial community (beta diversity) differed between patients with HF and healthy controls in both cohorts (P < 0.05). Patients with HF had shifts in the major bacterial phyla, resulting in a lower Firmicutes/Bacteroidetes (F/B) ratio than controls (P = 0.005). Patients reaching a clinical endpoint (listing for heart transplant or death) had lower bacterial richness and lower F/B ratio than controls (P < 0.01). Circulating levels of trimethylamine-N-oxide were associated with meat intake (P = 0.016), but not with gut microbiota alterations in HF. Low bacterial richness and low abundance of several genera in the Firmicutes phylum were associated with low fibre intake.

CONCLUSIONS

The gut microbiota in HF was characterized by decreased F/B ratio and reduced bacterial diversity associated with clinical outcome. The gut microbiota alterations in HF were partly related to low fibre intake, emphasizing the importance of diet as a covariate in future studies. Our data could provide a rationale for targeting the gut microbiota in HF with high-fibre diet.

Gut microbiota composition during a 12-week intervention with delayed-release dimethyl fumarate in multiple sclerosis - a pilot trial

Introduction

Patients with multiple sclerosis may have a distinct gut microbiota profile. Delayed-release dimethyl fumarate is an orally administered drug for relapsing-remitting multiple sclerosis, which has been associated with gastrointestinal side-effects in some patients.

Objectives

The purpose of this study was to determine if dimethyl fumarate alters the abundance and diversity of commensal gut bacteria, and if these changes are associated with gastrointestinal side-effects.

Methods

Thirty-six patients with relapsing-remitting multiple sclerosis received either dimethyl fumarate (n = 27) or an injectable multiple sclerosis disease-modifying therapy (glatiramer acetate or interferons, n = 9) for 12 weeks. Stool samples were collected at baseline, two and 12 weeks. We included 165 healthy individuals as controls.

Results

At baseline, 16 microbial genera were altered in multiple sclerosis patients compared with healthy controls. In the dimethyl fumarate-treated patients (n = 21) we observed a trend of reduced Actinobacteria (p = 0.03, Q_FDR = 0.24) at two weeks, mainly driven by Bifidobacterium (p = 0.06, Q_FDR = 0.69). At 12 weeks, we observed an increased abundance of Firmicutes (p = 0.02, Q_FDR = 0.09), mostly driven by Faecalibacterium (p = 0.01, Q_FDR = 0.48).

Conclusions

This pilot study did not detect a major effect of dimethyl fumarate on the gut microbiota composition, but we observed a trend towards normalization of the low abundance of butyrate-producing Faecalibacterium after 12 weeks treatment. The study was underpowered to link microbiota to gastrointestinal symptoms.

The gut microbial influence on cholestatic liver disease

Patients with cholestatic liver diseases like primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC) have a different gut microbiome composition than healthy controls. In contrast with PBC, PSC has a strong association with inflammatory bowel disease and is the prototypical disease of the gut-liver axis. Still, there are some distinct overlapping microbial features in the microbiome of patients with PSC and PBC suggesting similarities in cholestatic diseases, although the possible pathogenetic involvement of these shared microbial changes is unknown. Herein, we present an overview of the available data and discuss the relevance for potential disease relevant host-microbiota interactions. In general, the microbiome interacts with the host via the immunobiome (interactions between the host immune system and the gut microbiome), the endobiome (where the gut microbiome contributes to host physiology by producing or metabolizing endogenous molecules) and the xenobiome (gut microbial transformation of exogenous compounds, including nutrients and drugs). Experimental and human observational evidence suggest that the presence and functions of gut microbes are relevant for the severity and progression of cholestatic liver disease. Interestingly, the majority of new drugs that are currently being tested in PBC and PSC in clinical trials act on bile acid homeostasis, where the endobiome is important. In the future, it will be paramount to perform longitudinal studies, through which we can identify new intervention targets, biomarkers or treatment-stratifiers. In this way, gut microbiome-based clinical care and therapy may become relevant in cholestatic liver disease within the foreseeable future.

The carnitine-butyrobetaine-TMAO pathway after cardiac transplant: Impact on cardiac allograft vasculopathy and acute rejection

BACKGROUND

Alterations in the partly microbiota-dependent carnitine-γ-butyrobetaine (γBB)-trimethylamine N-oxide (TMAO) pathway have been linked to the progression of heart failure and atherosclerotic disease. We evaluated if circulating γBB, TMAO, and their common precursors carnitine and trimethyllysine (TML) were dysregulated after heart transplantation and associated with development of cardiac allograft vasculopathy (CAV) and acute rejection.

METHODS

We measured these metabolites in plasma from heart transplant recipients with everolimus-based (n = 32) and standard cyclosporine-based immunosuppression (n = 30) at different time-points and accompanied by assessment of CAV by intravascular ultrasound.

RESULTS

Baseline levels of carnitine, TMAO, and TML were elevated in heart transplant recipients compared with controls, and TML remained elevated throughout the observation period. The microbiota-dependent metabolite γBB increased steadily during 3 years of follow-up, with a similar decrease in its endogenous precursor TML. The increase in γBB and the change in TML were associated with a change in total atheroma volume from baseline to 3 years. Increases in γBB and carnitine levels from baseline to 1 year were associated with an increased frequency of acute rejection within the first year after heart transplant.

CONCLUSIONS

Our study reveals alterations of the carnitine-γBB-TMAO pathway after heart transplant, with increasing levels of γBB being associated with acute rejection and increase in total atheroma volume during 3 years of follow-up. Future studies should clarify whether interactions between dietary factors, immunosuppressive drugs, and the gut microbiota could influence acute rejection and CAV development to delineate mechanisms and potential novel treatment targets.

Autotaxin activity predicts transplant-free survival in primary sclerosing cholangitis

Autotaxin has been associated with liver disease severity and transplant-free survival. This study aimed to validate autotaxin as a biomarker in two cohorts of Norwegian large-duct PSC patients, one discovery panel (n = 165) and one validation panel (n = 87). Serum activity of autotaxin was measured in diluted sera by a fluorometric enzymatic assay. Patients reaching an end-point, liver transplantation or death, (discovery panel: n = 118 [71.5%]; validation panel: n = 35 [40.2%]), showed higher autotaxin activity compared with the other patients, P < 0.001 and P = 0.004, respectively. Kaplan-Meier survival analyses showed a strong association between increasing autotaxin activity and shorter liver transplant-free survival (discovery panel: P < 0.001, validation panel: P = 0.001). There was no relationship between autotaxin activity and the presence of inflammatory bowel disease or occurrence of hepatobiliary malignancy. In a multivariable analysis, high autotaxin activity was associated with an increased risk of liver transplantation or death (hazard ratio 2.03 (95% confidence interval 1.21–3.40), P < 0.01), independent from Mayo risk score, an in-house enhanced liver fibrosis score and interleukin-8 in serum. In conclusion, increased serum autotaxin activity is associated with reduced liver transplant-free survival independent from Mayo risk score and markers of inflammation and fibrosis.

Clinical response to fecal microbiota transplantation in patients with diarrhea-predominant irritable bowel syndrome is associated with normalization of fecal microbiota composition and short-chain fatty acid levels

Objectives: Irritable bowel syndrome (IBS) may be associated with disturbances in gut microbiota composition and functions. We recently performed a study of fecal microbiota transplantation (FMT) in diarrhea-predominant IBS (IBS-D) and found that IBS symptoms improved and the gut microbiota profile changed following FMT. We now aimed to explore the effects of FMT on the gut microenvironment in further detail by using 16S rRNA sequencing for more extended microbiota profiling and analyzing bacterial fermentation products (SCFAs: short chain fatty acids). Materials and methods: The study included 13 patients (four females and nine males) with IBS-D according to Rome III criteria and 13 healthy donors. Freshly donated feces were administered into duodenum via gastroscopy. The patients completed symptom and quality of life (QoL) questionnaires and delivered feces before and 1, 3, 12 and 20/28 weeks after FMT. Microbiota analysis was performed by sequencing 16S rRNA gene with Illumina Miseq technology. Fecal concentrations of SCFAs were analyzed by vacuum distillation followed by gas chromatography. Results: Several gut microbiota taxa and SCFAs were significantly different in the patients at baseline compared to their donors. These differences normalized by the third week following FMT in parallel with significant improvement in symptoms and QoL. Responders had different gut microbiota profile and SCFAs than nonresponders. Significant correlations were found between the gut microenvironment and IBS symptoms. No adverse effects were reported. Conclusions: FMT restores alterations of the gut microenvironment in IBS-D patients during the first 3 weeks and improves their symptoms for up to 28 weeks. ClinicalTrials.gov ID: NCT03333291.

Cholangiocarcinoma is associated with a raised enhanced liver fibrosis score independent of primary sclerosing cholangitis

BACKGROUND

Cholangiocarcinoma (CCA) complicates primary sclerosing cholangitis (PSC) in 10%-20% of cases, but current tools for prediction of a CCA diagnosis are inadequate. Recently, we demonstrated the utility of the enhanced liver fibrosis (ELF) test to stratify prognosis in PSC. We observed that patients with PSC + CCA had significantly higher ELF score than those with PSC alone. In this study, we aimed to investigate further this association in a larger cohort of PSC patients with CCA compared with patients with PSC or CCA alone.

MATERIALS AND METHODS

Stored sera from patients with PSC (n = 119), CCA without known chronic liver disease (n = 36) and PSC + CCA (n = 32) were tested for ELF. ELF score, gender, age, age at disease diagnosis, inflammatory bowel disease, PSC duration and severity, and CCA features were compared amongst the three cohorts. Factors related to an elevated ELF score were investigated.

RESULTS

Enhanced liver fibrosis score was significantly higher in patients with CCA without underlying chronic liver disease and in patients with PSC + CCA compared to those with PSC alone (P < 0.001). In multivariate analysis, elevated ELF score was associated with the diagnosis of CCA independently of age and PSC status (P < 0.001).

CONCLUSIONS

Enhanced liver fibrosis score was elevated in patients with CCA irrespective of the presence of PSC, and independently of liver disease stage. Our results indicate that the association between high ELF score and CCA may be related to the tumour's desmoplastic nature, independent of background liver fibrosis, suggesting that ELF score could be used to risk stratify for CCA in PSC.

Circulating markers of gut barrier function associated with disease severity in primary sclerosing cholangitis

BACKGROUND & AIMS

One important hypothesis in primary sclerosing cholangitis pathophysiology suggests that bacterial products from an inflamed leaky gut lead to biliary inflammation. We aimed to investigate whether circulating markers of bacterial translocation were associated with survival in a Norwegian primary sclerosing cholangitis cohort.

METHODS

Serum levels of zonulin, intestinal fatty acid binding protein, soluble CD14, lipopolysaccharide and lipopolysaccharide-binding protein were measured in 166 primary sclerosing cholangitis patients and 100 healthy controls.

RESULTS

Lipopolysaccharide-binding protein and soluble CD14 were elevated in primary sclerosing cholangitis compared with healthy controls (median 13 662 vs 12 339 ng/mL, P = 0.010 and 1657 vs 1196 ng/mL, P < 0.001, respectively). High soluble CD14 and lipopolysaccharide-binding protein (values >optimal cut-off using receiver operating characteristics) were associated with reduced liver transplantation-free survival (P < 0.001 and P = 0.005, respectively). The concentration of soluble CD14 was higher in patients with hepatobiliary cancer compared to other primary sclerosing cholangitis patients and healthy controls. Zonulin was lower in primary sclerosing cholangitis than controls, but when excluding primary sclerosing cholangitis patients with increased prothrombin time zonulin concentrations were similar in primary sclerosing cholangitis and healthy controls. Concomitant inflammatory bowel disease did not influence the results, while inflammatory bowel disease patients without primary sclerosing cholangitis (n = 40) had lower concentration of soluble CD14. In multivariable Cox regression, high soluble CD14 and high lipopolysaccharide-binding protein were associated with transplantation-free survival, independent from Mayo risk score (HR: 2.26 [95% CI: 1.15-4.43], P = 0.018 and HR: 2.00 [95% CI: 1.17-3.43], P = 0.011, respectively).

CONCLUSIONS

Primary sclerosing cholangitis patients show increased levels of circulating markers of bacterial translocation. High levels are associated with poor prognosis measured by transplantation-free survival, indicating that ongoing gut leakage could have clinical impact in primary sclerosing cholangitis.

Rifaximin alters gut microbiota profile, but does not affect systemic inflammation - a randomized controlled trial in common variable immunodeficiency

Common variable immunodeficiency (CVID) patients have reduced gut microbial diversity compared to healthy controls. The reduced diversity is associated with gut leakage, increased systemic inflammation and ten "key" bacteria that capture the gut dysbiosis (dysbiosis index) in CVID. Rifaximin is a broad-spectrum non-absorbable antibiotic known to reduce gut leakage (lipopolysaccharides, LPS) in liver disease. In this study, we explored as a 'proof of concept' that altering gut microbial composition could reduce systemic inflammation, using CVID as a disease model. Forty adult CVID patients were randomized, (1:1) to twice-daily oral rifaximin 550 mg versus no treatment for 2 weeks in an open-label, single-centre study. Primary endpoints were reduction in plasma/serum levels of soluble (s) CD14, sCD25, sCD163, neopterin, CRP, TNF, LPS and selected cytokines measured at 0, 2 and 8 weeks. Secondary endpoint was changes in intra-individual bacterial diversity in stool samples. Rifaximin-use did not significantly change any of the inflammation or gut leakage markers, but decreased gut microbial diversity compared with no treatment (p = 0.002). Importantly, the gut bacteria in the CVID dysbiosis index were not changed by rifaximin. The results suggest that modulating gut microbiota by rifaximin is not the chosen intervention to affect systemic inflammation, at least not in CVID.

The kinetics of gut microbial community composition in patients with irritable bowel syndrome following fecal microbiota transplantation

Background

Gut microbiota alterations are important in irritable bowel syndrome (IBS). The aim was to investigate the effect of fecal microbiota transplantation (FMT) on gut microbiota and the symptoms in patients with IBS.

Material and methods

The study included 13 IBS patients according to Rome III criteria and 13 healthy donors. Freshly donated feces were administered to the descending part of the duodenum via a gastroscope. Feces were collected from donors and patients before FMT, and from the patients at 1, 3 and 12 weeks and donors and patients at 20/28 weeks after FMT. Microbiota analysis was performed using GA-map Dysbiosis test (Genetic Analysis AS, Oslo, Norway). The patients completed the following questionnaires before and at the aforementioned weeks after FMT: IBS Symptom Questionnaire (IBS-SQ), IBS-Symptom Severity Scoring system (IBS-SSS), Short Form of Nepean Dyspepsia Index (SF-NDI), Bristol stool form scale, the Eysenck Personality Questionnaire-Neuroticism and Hospital Anxiety and Depression.

Results

Donors and IBS patients had significantly different bacterial strain signals before FMT (Ruminococcus gnavus, Actinobacteria and Bifidobacteria) that became non-significant after 3 weeks following FMT. The changes in gut microbiota were similar between donors and patients at 20/28 weeks after FMT. Thus, patients’ microbiota profiles became more-or-less similar to donors.

The scores of all the questionnaires were significantly improved at all time points following FMT. No reported adverse effects.

Conclusions

FMT was associated with a change in gut microbiota and improvement in IBS symptoms and quality of life lasting for up to 28 weeks.

Trial registration

ClinicalTrials.gov ID:NCT03333291