Association of the Kynurenine Pathway of Tryptophan Metabolism With Human Immunodeficiency Virus-Related Gut Microbiota Alterations and Visceral Adipose Tissue Accumulation.

BACKGROUND: The aim of the study was to investigate the association between human immunodeficiency virus (HIV)-related gut microbiota changes, alterations in the kynurenine (Kyn) pathway of tryptophan (Trp) metabolism, and visceral adipose tissue in the context of HIV infection. METHODS: Three hundred eighty-three people with HIV (PWH) were included from the Copenhagen comorbidity in HIV infection (COCOMO) study. Gut microbiota composition was analyzed by 16S ribosomal ribonucleic acid sequencing. Plasma metabolites were analyzed by liquid chromatography-tandem mass spectrometry. Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) areas were measured by single-slice computed tomography (CT) scan (4th lumbar vertebra). RESULTS: The HIV-related gut microbiota alterations were associated with lower Trp (ß -.01; 95% confidence interval [CI], -0.03 to -0.00) and higher Kyn-to-Trp ratio (ß 0.03; 95% CI, 0.01-0.05), which in turn was associated with higher VAT-to-SAT ratio (ß 0.50; 95% CI, 0.10-0.90) and larger VAT area (ß 30.85; 95% CI, 4.43-57.28). In mediation analysis, the Kyn-to-Trp ratio mediated 10% (P = .023) of the association between the VAT-to-SAT ratio and HIV-related gut microbiota. CONCLUSIONS: Our data suggest HIV-related gut microbiota compositional changes and gut microbial translocation as potential drivers of high Kyn-to-Trp ratio in PWH. In turn, increased activity in the Kyn pathway of Trp metabolism was associated with larger visceral adipose tissue area. Taken together, our findings suggest a possible role for this pathway in the gut-adipose tissue axis in the context of HIV infection.

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.

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, QFDR = 0.24) at two weeks, mainly driven by Bifidobacterium (p = 0.06, QFDR = 0.69). At 12 weeks, we observed an increased abundance of Firmicutes (p = 0.02, QFDR = 0.09), mostly driven by Faecalibacterium (p = 0.01, QFDR = 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.

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.

Serological markers of extracellular matrix remodeling predict transplant-free survival in primary sclerosing cholangitis.

BACKGROUND: Primary sclerosing cholangitis is a progressive liver disease with a remarkably variable course. Biomarkers of disease activity or prognostic models predicting outcome at an individual level are currently not established. AIM: To evaluate the prognostic utility of four biomarkers of basement membrane and interstitial extracellular matrix remodeling in patients with primary sclerosing cholangitis. METHODS: Serum samples were available from 138 large-duct primary sclerosing cholangitis patients (of which 102 [74%] with IBD) recruited 2008-2012 and 52 ulcerative colitis patients (controls). The median follow-up time was 2.2 (range 0-4.3) years. Specific biomarkers of type III and V collagen formation (PRO-C3 and PRO-C5, respectively) and type III and IV collagen degradation (C3M and C4M, respectively) were assessed. The Enhanced Liver Fibrosis test, including procollagen type III N-terminal peptide, tissue inhibitor of metalloproteinase-1 and hyaluronic acid was assessed for comparison. RESULTS: All markers were elevated in primary sclerosing cholangitis compared to ulcerative colitis patients (P < 0.001). PRO-C3 showed the largest difference between the two groups with a threefold increase in primary sclerosing cholangitis compared to ulcerative colitis patients. Patients with high baseline serum levels of all markers, except C3M, had shorter survival compared to patients with low baseline serum levels (P < 0.001). Combining PRO-C3 and PRO-C5 the odds ratio for predicting transplant-free survival was 47 compared to the Enhanced Liver Fibrosis test's odds ratio of 11. CONCLUSIONS: Extracellular matrix remodeling is elevated in primary sclerosing cholangitis patients compared to ulcerative colitis patients. Furthermore, the interstitial matrix marker PRO-C3 was identified as a potent prognostic marker and an independent predictor of transplant-free survival in primary sclerosing cholangitis.

Recurrent attacks of acute hepatic porphyria: major role of the chronic inflammatory response in the liver.

BACKGROUND: Acute intermittent porphyria (AIP) is an inherited disorder of haem metabolism characterized by life-threatening acute neurovisceral attacks due to the induction of hepatic δ-aminolevulinic acid synthase 1 (ALAS1) associated with hydroxymethylbilane synthase (HMBS) deficiency. So far, the treatment of choice is hemin which represses ALAS1. The main issue in the medical care of AIP patients is the occurrence of debilitating recurrent attacks. OBJECTIVE: The aim of this study was to determine whether chronic hemin administration contributes to the recurrence of acute attacks. METHODS: A follow-up study was conducted between 1974 and 2015 and included 602 French AIP patients, of whom 46 had recurrent AIP. Moreover, we studied the hepatic transcriptome, serum proteome, liver macrophage polarization and oxidative and inflammatory profiles of Hmbs-/- mice chronically treated by hemin and extended the investigations to five explanted livers from recurrent AIP patients. RESULTS: The introduction of hemin into the pharmacopeia has coincided with a 4.4-fold increase in the prevalence of chronic patients. Moreover, we showed that both in animal model and in human liver, frequent hemin infusions generate a chronic inflammatory hepatic disease which induces HO1 remotely to hemin treatment and maintains a high ALAS1 level responsible for recurrence. CONCLUSION: Altogether, this study has important impacts on AIP care underlying that hemin needs to be restricted to severe neurovisceral crisis and suggests that alternative treatment targeting the liver such as ALAS1 and HO1 inhibitors, and anti-inflammatory therapies should be considered in patients with recurrent AIP.

HLA haplotypes in primary sclerosing cholangitis patients of admixed and non-European ancestry.

Primary sclerosing cholangitis (PSC) is strongly associated with several human leukocyte antigen (HLA) haplotypes. Due to extensive linkage disequilibrium and multiple polymorphic candidate genes in the HLA complex, identifying the alleles responsible for these associations has proven difficult. We aimed to evaluate whether studying populations of admixed or non-European descent could help in defining the causative HLA alleles. When assessing haplotypes carrying HLA-DRB1*13:01 (hypothesized to specifically increase the susceptibility to chronic cholangitis), we observed that every haplotype in the Scandinavian PSC population carried HLA-DQB1*06:03. In contrast, only 65% of HLA-DRB1*13:01 haplotypes in an admixed/non-European PSC population carried this allele, suggesting that further assessments of the PSC-associated haplotype HLA-DRB1*13:01-DQA1*01:03-DQB1*06:03 in admixed or multi-ethnic populations could aid in identifying the causative allele.

Serum metabolomic profiling highlights pathways associated with liver fat content in a general population sample.

BACKGROUND/OBJECTIVES: Fatty liver disease (FLD) is an important intermediate trait along the cardiometabolic disease spectrum and strongly associates with type 2 diabetes. Knowledge of biological pathways implicated in FLD is limited. An untargeted metabolomic approach might unravel novel pathways related to FLD. SUBJECTS/METHODS: In a population-based sample (n=555) from Northern Germany, liver fat content was quantified as liver signal intensity using magnetic resonance imaging. Serum metabolites were determined using a non-targeted approach. Partial least squares regression was applied to derive a metabolomic score, explaining variation in serum metabolites and liver signal intensity. Associations of the metabolomic score with liver signal intensity and FLD were investigated in multivariable-adjusted robust linear and logistic regression models, respectively. Metabolites with a variable importance in the projection >1 were entered in in silico overrepresentation and pathway analyses. RESULTS: In univariate analysis, the metabolomics score explained 23.9% variation in liver signal intensity. A 1-unit increment in the metabolomic score was positively associated with FLD (n=219; odds ratio: 1.36; 95% confidence interval: 1.27-1.45) adjusting for age, sex, education, smoking and physical activity. A simplified score based on the 15 metabolites with highest variable importance in the projection statistic showed similar associations. Overrepresentation and pathway analyses highlighted branched-chain amino acids and derived gamma-glutamyl dipeptides as significant correlates of FLD. CONCLUSIONS: A serum metabolomic profile was associated with FLD and liver fat content. We identified a simplified metabolomics score, which should be evaluated in prospective studies.

Altered gut microbiota profile in common variable immunodeficiency associates with levels of lipopolysaccharide and markers of systemic immune activation.

Common variable immunodeficiency (CVID) is the most common symptomatic primary immunodeficiency characterized by low immunoglobulin (Ig)G and IgA, and/or IgM. In addition to bacterial infections, a large subgroup has noninfectious inflammatory and autoimmune complications. We performed 16S ribosomal RNA-based profiling of stool samples in 44 CVID patients, 45 patients with inflammatory bowel disease (disease controls), and 263 healthy controls. We measured plasma lipopolysaccharide (LPS) and markers of immune cell activation (i.e., soluble (s) CD14 and sCD25) in an expanded cohort of 104 patients with CVID and in 30 healthy controls. We found a large shift in the microbiota of CVID patients characterized by a reduced within-individual bacterial diversity (alpha diversity, P<0.001) without obvious associations to antibiotics use. Plasma levels of both LPS (P=0.001) and sCD25 (P<0.0001) were elevated in CVID, correlating negatively with alpha diversity and positively with a dysbiosis index calculated from the taxonomic profile. Low alpha diversity and high dysbiosis index, LPS, and immune markers were most pronounced in the subgroup with inflammatory and autoimmune complications. Low level of IgA was associated with decreased alpha diversity, but not independently from sCD25 and LPS. Our findings suggest a link between immunodeficiency, systemic immune activation, LPS, and altered gut microbiota.

Characterization of Intestinal Microbiota in Ulcerative Colitis Patients with and without Primary Sclerosing Cholangitis.

BACKGROUND AND AIMS: There is an unexplained association between ulcerative colitis [UC] and primary sclerosing cholangitis [PSC], with the intestinal microbiota implicated as an important factor. The study aim was to compare the structure of the intestinal microbiota of patients with UC with and without PSC. METHODS: UC patients with PSC [PSC-UC] and without PSC [UC] were identified from biobanks at Oslo University Hospital, Foothills Hospital Calgary and Mount Sinai Hospital Toronto. Microbial DNA was extracted from colonic tissue and sequencing performed of the V4 region of the 16S rRNA gene on Illumina MiSeq. Sequences were assigned to operational taxonomic units [OTUs] using Quantitative Insights Into Microbial Ecology [QIIME]. Microbial alpha diversity, beta diversity, and relative abundance were compared between PSC-UC and UC phenotypes. RESULTS: In all, 31 PSC-UC patients and 56 UC patients were included. Principal coordinate analysis [PCoA] demonstrated that city of sample collection was the strongest determinant of taxonomic profile. In the Oslo cohort, Chao 1 index was modestly decreased in PSC-UC compared with UC [p = 0.04] but did not differ significantly in the Calgary cohort. No clustering by PSC phenotype was observed using beta diversity measures. For multiple microbial genera there were nominally significant differences between UC and PSC-UC, but results were not robust to false-discovery rate correction. CONCLUSIONS: No strong PSC-specific microbial associations in UC patients consistent across different cohorts were identified. Recruitment centre had a strong effect on microbial composition. Future studies should include larger cohorts to increase power and the ability to control for confounding factors.

Microbiota-dependent metabolite trimethylamine-N-oxide is associated with disease severity and survival of patients with chronic heart failure.

OBJECTIVES: Recent metabolomic, experimental and clinical studies have demonstrated that trimethylamine-N-oxide (TMAO), a microbiota-dependent metabolite from dietary phosphatidylcholine and carnitine, is a strong predictor of coronary artery disease (CAD). This finding suggests a link between the gut microbiota and atherosclerosis. The potential impact of TMAO in chronic heart failure (HF) is unknown. We hypothesized that TMAO levels would provide prognostic information about adverse outcomes in chronic HF. DESIGN: Prospective, observational study including 155 consecutive patients with chronic HF. In addition, 100 patients with stable CAD without HF and 33 matched healthy individuals were included as controls. Plasma levels of TMAO and its precursors choline and betaine were measured, and associations with symptoms, aetiology and transplant-free survival in the patients with HF were explored. RESULTS: Plasma levels of TMAO (P = 0.01), choline (P < 0.001) and betaine (P < 0.001) were elevated in patients with chronic HF compared to control subjects, with the highest levels in patients with New York Heart Association (NYHA) classes III and IV. Furthermore, TMAO levels were highest in individuals with ischaemic HF, followed by those with stable CAD and nonischaemic HF. TMAO, but not choline or betaine, was associated with reduced transplant-free survival: approximately 50% of patients in the upper tertile of TMAO levels died or received a heart transplant during 5.2 years of follow-up (unadjusted Cox-regression: hazard ratio 2.24, 95% confidence interval 1.28-3.92, P = 0.005). CONCLUSIONS: TMAO levels were elevated in patients with HF and associated with NYHA class, ischaemic aetiology and adverse outcomes. Future studies should focus on gut microbiota, dietary composition and intestinal dysfunction in relation to TMAO levels and clinical outcome in HF.

Agreement of a child's respiratory symptom diary with parental reports and peak expiratory flow.

OBJECTIVE: To assess the agreement of a self-completed diary to monitor respiratory symptoms in children aged 6-12 years with parental symptom reports and fluctuations in lung function. DESIGN: We created a text- and symbol-based questionnaire for daily completion by children at school. Using a screening questionnaire completed by the parents, we selected 101 children with lower respiratory symptoms in the last year or doctor-diagnosed asthma to complete the diary. We assessed the agreement with a parent-completed daily symptom diary and measurements of peak expiratory flow (PEF) over 5 weeks, estimating % agreement and the kappa statistic (kappa) for pairwise comparisons. RESULTS: Simple agreement between PEF variability, parent-reported and child-reported symptoms was moderate to high. Using kappa, agreement between children's and parents' reports of respiratory symptoms was only fair to moderate, and agreement with lung function measurements was poor for both parent- and child-reported symptoms. CONCLUSION: Agreement between children's and parents' reports on day-to-day respiratory symptoms was fair to moderate. The children's symptom diary agreed poorly with lung function measurements, but was neither worse nor better than the parent-completed diary.