BackgroundThe microbial metabolite Trimethylamine-N-oxide (TMAO) has been linked to adverse cardiovascular outcome and mortality in the general population.ObjectiveTo assess the contribution of TMAO to inflammation and mortality in chronic kidney disease (CKD) patients ranging from mild-moderate to end-stage disease and 1) associations with glomerular filtration rate (GFR) 2) effect of dialysis and renal transplantation (Rtx) 3) association with inflammatory biomarkers and 4) its predictive value for all-cause mortality.MethodsLevels of metabolites were quantified by a novel liquid chromatography/tandem mass spectrometry-based method in fasting plasma samples from 80 controls and 179 CKD 3–5 patients. Comorbidities, nutritional status, biomarkers of inflammation and GFR were assessed.ResultsGFR was the dominant variable affecting TMAO (β = -0.41; p<0.001), choline (β = -0.38; p<0.001), and betaine (β = 0.45; p<0.001) levels. A longitudinal study of 74 CKD 5 patients starting renal replacement therapy demonstrated that whereas dialysis treatment did not affect TMAO, Rtx reduced levels of TMAO to that of controls (p<0.001). Following Rtx choline and betaine levels continued to increase. In CKD 3–5, TMAO levels were associated with IL-6 (Rho = 0.42; p<0.0001), fibrinogen (Rho = 0.43; p<0.0001) and hsCRP (Rho = 0.17; p = 0.022). Higher TMAO levels were associated with an increased risk for all-cause mortality that remained significant after multivariate adjustment (HR 4.32, 95% CI 1.32–14.2; p = 0.016).ConclusionElevated TMAO levels are strongly associated with degree of renal function in CKD and normalize after renal transplantation. TMAO levels correlates with increased systemic inflammation and is an independent predictor of mortality in CKD 3–5 patients.

Our data does not support that TMAO is a significant link between gut dysbiosis and inflammation in HIV-1-infection. We propose that HIV-1, microbial composition and ART disparately confound TMAO levels, thus limiting its role as a cardiovascular risk marker in HIV-1-infected individuals.

Dysbiosis and a dysregulated gut immune barrier function contributes to chronic immune activation in HIV-1 infection. We investigated if nutritional supplementation with vitamin D and phenylbutyrate could improve gut-derived inflammation, selected microbial metabolites, and composition of the gut microbiota. Treatment-naïve HIV-1-infected individuals (n = 167) were included from a double-blind, randomized, and placebo-controlled trial of daily 5000 IU vitamin D and 500 mg phenylbutyrate for 16 weeks (Clinicaltrials.gov NCT01702974). Baseline and per-protocol plasma samples at week 16 were analysed for soluble CD14, the antimicrobial peptide LL-37, kynurenine/tryptophan-ratio, TMAO, choline, and betaine. Assessment of the gut microbiota involved 16S rRNA gene sequencing of colonic biopsies. Vitamin D + phenylbutyrate treatment significantly increased 25-hydroxyvitamin D levels (p < 0.001) but had no effects on sCD14, the kynurenine/tryptophan-ratio, TMAO, or choline levels. Subgroup-analyses of vitamin D insufficient subjects demonstrated a significant increase of LL-37 in the treatment group (p = 0.02), whereas treatment failed to significantly impact LL-37-levels in multiple regression analysis. Further, no effects on the microbiota was found in number of operational taxonomic units (p = 0.71), Shannon microbial diversity index (p = 0.82), or in principal component analyses (p = 0.83). Nutritional supplementation with vitamin D + phenylbutyrate did not modulate gut-derived inflammatory markers or microbial composition in treatment-naïve HIV-1 individuals with active viral replication.

Methicillin-resistant Staphylococcus aureus (MRSA) is resistant to all beta-lactam antibiotics and can cause severe infections that are difficult to treat. Eradication strategies with conventional antibiotics are not always effective and alternative approaches are warranted. Here, we tested the hypothesis that daily supplementation with vitamin D for 12 months would reduce MRSA carriage rates among a group of persistent carriers. This was a double-blind, placebo-controlled randomized trial with n = 65 persistent MRSA carriers with 25-hydroxy vitamin D3 (25OHD) < 75 nmol/L, who were followed up with bacterial cultures at baseline and every 3 months for 1 year. The primary endpoint was the decline in MRSA positivity during the study period. The study was conducted in two MRSA outpatient clinics at the Karolinska University Hospital, Stockholm, Sweden. In total, n = 65 persistent MRSA carriers were randomized and n = 3 were lost to follow-up. Only patients deficient in vitamin D (< 75 nmol/L) were included. Vitamin D (4000 IU) or placebo/day was administered for 12 months. The decline in MRSA positivity was equal in the vitamin D and placebo group during the study period (OR, 1.00; 95% CI, 0.97–1.03; p = 0.928) and approximately 40% in both groups were MRSA-negative after 12 months. The vitamin D group produced 103 positive cultures out of 318 cultures (32.4%) from nose, throat, and perineum over the study period, whereas the placebo group produced 135/393 positive cultures (34.0%) (Fisher’s exact test, p = 0.94). Vitamin D supplementation did not influence MRSA carriage. Thus, available data does not support vitamin D supplementation to persistent MRSA carriers.Trial registration: www.clinicaltrials.gov; NCT02178488.Electronic supplementary materialThe online version of this article (10.1007/s10096-018-3306-7) contains supplementary material, which is available to authorized users.

To study vitamin D (25OH D3) in relation to (i) microbial translocation (ii) systemic inflammation and (iii) blood lipid markers, in Caucasian, well-controlled HIV patients and healthy controls, plasma and serum samples from n = 97 male, HIV patients on HAART with immeasurable viral load (<20 copies/ml) since median 6.5 years and no concurrent inflammatory or infectious disease and n = 30 healthy controls were analysed for (i) LPS; (ii) sCD14, hsCRP, IL-4, IL-6, IL-10, IL-17, MCP-1 and IFN-γ; as well as (iii) blood lipids. Vitamin D levels were similarly distributed and equally low in both HIV patients and controls. There was no association between vitamin D levels and markers of microbial translocation, systemic inflammation or dyslipidemia. LPS levels were similar in both groups but HIV patients expressed higher levels of sCD14 and hsCRP, with HIV as an independent risk factor. HIV patients had higher cholesterol and Apo B levels. Notably, more HIV patients smoked and smoking was associated with lower vitamin D levels. In conclusion; these well-treated Caucasian HIV patients had similar vitamin D levels as healthy controls. However, despite perfect virological control, they exhibited slightly increased inflammatory markers and disturbed blood lipids. However, neither of these parameters were associated with low vitamin D levels but appeared to be linked to the HIV-disease per se. Thus, the rationale for vitamin D substitution as a way to improve microbial translocation and systemic inflammation is not fully supported in this HIV population.