Insights in the regulation of trimetylamine N-oxide production using a comparative biomimetic approach suggest a metabolic switch in hibernating bears

Experimental studies suggest involvement of trimethylamine N-oxide (TMAO) in the aetiology of cardiometabolic diseases and chronic kidney disease (CKD), in part via metabolism of ingested food. Using a comparative biomimetic approach, we have investigated circulating levels of the gut metabolites betaine, choline, and TMAO in human CKD, across animal species as well as during hibernation in two animal species. Betaine, choline, and TMAO levels were associated with renal function in humans and differed significantly across animal species. Free-ranging brown bears showed a distinct regulation pattern with an increase in betaine (422%) and choline (18%) levels during hibernation, but exhibited undetectable levels of TMAO. Free-ranging brown bears had higher betaine, lower choline, and undetectable TMAO levels compared to captive brown bears. Endogenously produced betaine may protect bears and garden dormice during the vulnerable hibernating period. Carnivorous eating habits are linked to TMAO levels in the animal kingdom. Captivity may alter the microbiota and cause a subsequent increase of TMAO production. Since free-ranging bears seems to turn on a metabolic switch that shunts choline to generate betaine instead of TMAO, characterisation and understanding of such an adaptive switch could hold clues for novel treatment options in burden of lifestyle diseases, such as CKD.

Pro-neurotensin depends on renal function and is related to all-cause mortality in chronic kidney disease

BACKGROUND

Patients with chronic kidney disease (CKD) have a high risk of premature cardiovascular diseases (CVD) and show increased mortality. Pro-neurotensin (Pro-NT) was associated with metabolic diseases and predicted incident CVD and mortality. However, Pro-NT regulation in CKD and its potential role linking CKD and mortality have not been investigated, so far.

METHODS

In a central lab, circulating Pro-NT was quantified in three independent cohorts comprising 4715 participants (cohort 1: patients with CKD; cohort 2: general population study; and cohort 3: non-diabetic population study). Urinary Pro-NT was assessed in part of the patients from cohort 1. In a 4th independent cohort, serum Pro-NT was further related to mortality in patients with advanced CKD. Tissue-specific Nts expression was further investigated in two mouse models of diabetic CKD and compared to non-diabetic control mice.

RESULTS

Pro-NT significantly increased with deteriorating renal function (P < 0.001). In meta-analysis of cohorts 1-3, Pro-NT was significantly and independently associated with estimated glomerular filtration rate (P ≤ 0.002). Patients in the middle/high Pro-NT tertiles at baseline had a higher all-cause mortality compared to the low Pro-NT tertile (Hazard ratio: 2.11, P = 0.046). Mice with severe diabetic CKD did not show increased Nts mRNA expression in different tissues compared to control animals.

CONCLUSIONS

Circulating Pro-NT is associated with impaired renal function in independent cohorts comprising 4715 subjects and is related to all-cause mortality in patients with end-stage kidney disease. Our human and rodent data are in accordance with the hypotheses that Pro-NT is eliminated by the kidneys and could potentially contribute to increased mortality observed in patients with CKD.

P0714RELATIONSHIP BETWEEN BIOLOGICAL AGE ESTIMATED BY SKIN AUTOFLUORESCENCE, CHRONOLOGICAL AGE, AND MORTALITY IN CHRONIC KIDNEY DISEASE

Background and Aims

While chronological age associates with increased risk of death, there is a quest for markers of biological age in chronic kidney disease (CKD) that better reflect accumulation of tissue and cellular damage, which could contribute to shorter life span. Skin autofluorescence (SAF) is a biomarker for accumulation of advanced glycation end products in skin that associate with chronological age and with factors that may increase mortality risk. However, the predictive capacity of SAF for mortality has not been fully elucidated in CKD. We have investigated the relationship between biological age calculated by SAF, chronological age and all-cause mortality in patients with CKD stage 5.

Method

In a cohort of 199 CKD5 patients (non-dialysis CKD5, n=100, hemodialysis, n=27 and peritoneal dialysis, n=72; median age 66 years, 34% females, 21% diabetes (DM), 20% cardiovascular disease (CVD), and 34% malnourished), we calculated biological age by a formula based on SAF measurements using the AGE Reader. Framingham risk score, coronary artery calcium score, the heart rate-corrected augmentation index, body composition, nutritional status, handgrip strength, and various biochemical markers (hemoglobin, albumin, creatinine, intact-parathyroid hormone, triglyceride, cholesterol, HDL-cholesterol, high-sensitivity C-reactive protein (hsCRP), and interleukin (IL)-6) were recorded at baseline. During median follow-up of 38 months, 34 patients died, and 51 patients underwent renal transplantation. We analyzed spline curves showing sub-distribution hazard risk (sHR) for all-cause mortality with biological age calculated by SAF and chronological age by the Fine and Gray competing risk analysis.

Results

There was a significant association between biological age calculated by SAF and chronological age (rho=0.48; p&lt;0.001). IL-6 and hsCRP were positively associated both with biological age according to SAF measurement (IL-6: rho=0.34, p&lt;0.001; n=155 and hsCRP: rho=0.31, p&lt;0.001; n=199) and chronological age (IL-6: rho=0.47, p&lt;0.001; n=155 and hsCRP: rho=0.40, p&lt;0.001; n=199). The multivariate spline curve showing sHR for all-cause mortality associated positively with chronological age (sHR: 1.04, p=0.035) and biological age calculated by SAF (sHR: 1.01, p=0.048) when adjusted for sex, DM, CVD, nutritional status, 1-standard deviation increase of hsCRP, and CKD5 groups.

Conclusion

All-cause mortality risk increased linearly with higher chronological age and SAF-estimated biological age - and with similar magnitude of sHR for the two - suggesting that prediction of mortality risk based on SAF is not superior compared to chronological age in CKD. We conclude that biological age calculated by SAF and chronological age are equally robust predictors of clinical outcomes in CKD; however, both indices are influenced by the inflammatory status.

P0669HIGH ESTIMATED PHENOTYPIC AGE ASSOCIATES WITH WORSE CLINICAL OUTCOME IN CHRONIC KIDNEY DISEASE PATIENTS

Background and Aims

Ageing represents the greatest risk factor contributing to increased morbidity and mortality in most chronic diseases; it encompasses numerous biological changes resulting in declining physiological function and increasing burden of disease. Whether new biomarkers of ageing and risk scores for predicting physiological outcomes, including mortality, are applicable and more accurate than chronological age in patients with chronic kidney disease (CKD) is not clear. So far, the DNA methylation (DNAm) PhenoAge biomarker of ageing (Levine et al. Aging 2018) has not been tested in CKD. While we had no access to DNAm data, we applied the phenotypic age estimate proposed by Levine et al., which was included in their calculations of DNAm PhenoAge, and tested the relationship between estimated phenotypic age (ePhenoAge) and chronological age, respectively, with all-cause mortality in patients with CKD.

Method

In a cohort of 333 CKD patients (stage 1, n=78; stage 3-4, n=64; and stage 5, n=191) with median age 56 years, 43% females, 24% diabetes (DM), 25% cardiovascular disease (CVD), and 22% malnourished, we estimated age by ePhenoAge, using a formula with calculations based on nine biomarkers and chronological age, and compared this age index with chronological age. Framingham risk score, body composition, nutritional status, handgrip strength, and various biochemical markers (white blood cells, mean cell volume, hemoglobin, albumin, creatinine, glucose, calcium, alkaline phosphatase, intact-parathyroid hormone, triglyceride, cholesterol, HDL-cholesterol, high-sensitivity C-reactive protein (hsCRP), and interleukin (IL)-6) were recorded. During a median follow-up period of 52 months, 65 patients died, and 111 patients underwent renal transplantation. We used spline curve to illustrate sub-distribution hazard risk (sHR) for all-cause mortality versus increasing ePhenoAge and chronological age respectively as obtained by the Fine and Gray competing risk analysis.

Results

In univariate analyses, IL-6 (rho=0.49, p&lt;0.001; n=268) and hsCRP (rho=0.37, p&lt;0.001; n=333) were significantly correlated with ePhenoAge. The ePhenoAge remained significantly associated with hsCRP (p=0.02) when adjusted for sex, DM, CVD, nutritional status and CKD stages. The spline curves showing sHR for all-cause mortality derived from multivariate competing risk analysis and adjusted for sex, presence of DM and CVD, hsCRP, nutritional status and CKD stages, showed increased mortality risk with higher chronological age (sHR: 1.08, p&lt;0.001). In contrast, the association of mortality with higher ePhenoAge (sHR: 1.04, p=0.06) was of borderline statistical significance.

Conclusion

All-cause mortality risk was associated with increasing chronological age in competing risk analysis with adjustments of confounders. A similar trend was observed for ePhenoAge, a finding which to a large extent may be explained by the inflammatory status of the study subjects. However, contrary to expectations, ePhenoAge was not as powerful as chronological age in predicting mortality, underlining that our knowledge about factors influencing phenotypic age in CKD patients is still limited. This should motivate further study of the potential role of other estimates of biological age in CKD.

Oligoadenylate Synthetase 1 enhances DNA sensor cGAS translation to mediate WNV antiviral activity

Interferons inhibit virus replication through the expression of interferon stimulated genes (ISGs). We have found that a specific isoform of one such ISG, Oligoadenylate Synthetase 1 (OAS1) limits host susceptibility to West Nile Virus (WNV) infection through a non-canonical mechanism. This OAS1 isoform (OAS1 P46) in humans is generated due to an alternative splice acceptor site at the C-terminus of OAS1 gene. The SNP rs10774671 at this site has been associated with disease severity to WNV. We show that human OAS1-KO cells have lower basal levels of cGAS protein and can be rescued by OAS1 P46 independent of its enzyme activity. Additionally, through RNA-seq, SILAC, polysome profiling and radiolabeling experiments, we show that OAS1 does not regulate mRNA transcription but instead enhances protein translation of a select set of mRNAs, thereby increasing the steady state and induced levels of specific proteins with antiviral properties. Inducible expression of OAS1 P46 in cGAS-KO cells does not suppress WNV replication, suggesting that the antiviral activity of OAS1 is mediated through cGAS. We also have established functional equivalence between OAS1 P46 and a mouse ortholog, Oas1b (no enzyme activity), which similarly affects WNV susceptibility. Oas1b inhibits WNV infection and pathogenesis in vivo and inhibits WNV infection in vitro in cGAS-dependent manner. Through RNA-protein crosslinking experiments we have identified target mRNAs that bind to OAS1 and have demonstrated increased sensitivity of WNV in Oas1b RNA binding mutants. Our findings suggest a novel mechanism of OAS1 in which it binds to target mRNAs, enhances the translation of these RNAs and limits virus infection.

[Treatment mapping of lower urinary tract symptoms due to benign prostatic hyperplasia-an analysis of the Governing Body of German Prostate Centers]

BACKGROUND

Due to the high incidence and demographic development, there is an urgent need for healthcare research data on lower urinary tract symptoms due to benign prostatic hyperplasia (LTUS/BPH). Since 2005 the Governing Body of German Prostate Centers (DVPZ) has been collecting data from 22 prostate centers in order to determine the quality and type of cross-sectoral care in particular for LUTS/BPH patients.

OBJECTIVES

Presentation of the DVPZ database in general, as well as an investigation of treatment patterns for medical and instrumental therapies.

MATERIALS AND METHODS

The analysis is based on UroCloud data sets from 30 November 2017. In the UroCloud data on diagnostics, therapy and course of disease are recorded in a web-based manner.

RESULTS

A total of 29,555 therapies were documented for 18,299 patients (1.6/patient), divided into 48.5% instrumental, 29.2% medical treatment, and 18.0% "wait and see" (in 4.3% no assignment was possible). Patients treated with an instrumental therapy were oldest (median: 72 years, interquartile range: 66-77), had the largest prostate volumes (50 ml, 35-75 ml), and were mostly bothered by symptoms (International Prostate Symptom Score = 19/4). The majority of patients under medical treatment received alphablockers (56%); phytotherapeutics were used least frequently (3%). Instrumental therapies are dominated by transurethral resection (TUR) of the prostate (60.0%), open prostatectomy (9.4%) and laser therapy (5.0%), with laser therapy having the shortest hospital stay (5 days) and the lowest transfusion and re-intervention rates (1.0% and 4.6%, respectively).

CONCLUSIONS

The DVPZ certificate covers the complete spectrum of cross-sectoral care for LUTS/BPH patients and documents the use of the various therapies as well as their application and effectiveness in the daily routine setting.

Inflammation and Premature Ageing in Chronic Kidney Disease

Persistent low-grade inflammation and premature ageing are hallmarks of the uremic phenotype and contribute to impaired health status, reduced quality of life, and premature mortality in chronic kidney disease (CKD). Because there is a huge global burden of disease due to CKD, treatment strategies targeting inflammation and premature ageing in CKD are of particular interest. Several distinct features of the uremic phenotype may represent potential treatment options to attenuate the risk of progression and poor outcome in CKD. The nuclear factor erythroid 2-related factor 2 (NRF2)-kelch-like erythroid cell-derived protein with CNC homology [ECH]-associated protein 1 (KEAP1) signaling pathway, the endocrine phosphate-fibroblast growth factor-23-klotho axis, increased cellular senescence, and impaired mitochondrial biogenesis are currently the most promising candidates, and different pharmaceutical compounds are already under evaluation. If studies in humans show beneficial effects, carefully phenotyped patients with CKD can benefit from them.

The brown fat-secreted adipokine neuregulin 4 is decreased in human and murine chronic kidney disease

OBJECTIVE

Neuregulin 4 (NRG4) has recently been introduced as a novel brown adipose tissue (BAT)-secreted adipokine with beneficial metabolic effects in mice. However, regulation of Nrg4 in end-stage kidney disease (ESKD) and type 2 diabetes mellitus (T2DM) has not been elucidated, so far.

DESIGN/METHODS

Serum NRG4 levels were quantified by ELISA in 60 subjects with ESKD on chronic hemodialysis as compared to 60 subjects with an estimated glomerular filtration rate >50 mL/min/1.73 m2 in a cross-sectional cohort. Within both groups, about half of the patients had a T2DM. Furthermore, mRNA expression of Nrg4 was determined in two mouse models of diabetic kidney disease (DKD) as compared to two different groups of non-diabetic control mice. Moreover, mRNA expression of Nrg4 was investigated in cultured, differentiated mouse brown and white adipocytes, as well as hepatocytes, after treatment with the uremic toxin indoxyl sulfate.

RESULTS

Median serum NRG4 was significantly lower in patients with ESKD compared to controls and the adipokine was independently associated with a beneficial renal, glucose and lipid profile. In mice with DKD, Nrg4 mRNA expression was decreased in all adipose tissue depots compared to control mice. The uremic toxin indoxyl sulfate did not significantly alter Nrg4 mRNA expression in adipocytes and hepatocytes, in vitro.

CONCLUSIONS

Circulating NRG4 is independently associated with a preserved renal function and mRNA expression of -Nrg4 is reduced in adipose tissue depots of mice with DKD. The BAT-secreted adipokine is further associated with a beneficial glucose and lipid profile supporting NRG4 as potential treatment target in metabolic and renal disease states.

New Organic Electrode Materials for Ultrafast Electrochemical Energy Storage

Organic materials are both environmentally and economically attractive as potential electrode candidates. This Research News reports on a new class of stable and electrically conductive organic electrodes based on metal porphyrins with functional groups that are capable of electrochemical polymerization, rendering the materials promising for electrochemical applications. Their structural flexibility and the unique highly conjugated macrocyclic structure allows the produced organic electrodes to act as both cathode and anode materials giving access to fast charging as well as high cycling stability. The extreme thermal and chemical stability of the porphyrin-based organic electrodes and their chemical versatility suggest an important role for these molecular systems in the further development of novel electrochemical energy storage applications.

Circulating Pro-Neurotensin in gestational diabetes mellitus

BACKGROUND AND AIMS

Pro-Neurotensin (NT), a stable surrogate parameter of NT, has recently been introduced as a peptide predicting the development of obesity, diabetes mellitus, cardiovascular diseases, and cardiovascular mortality. However, regulation of Pro-NT in gestational diabetes mellitus (GDM) remains uninvestigated.

METHODS AND RESULTS

Pro-NT was quantified in 74 women with GDM, 74 healthy, gestational age-matched, pregnant controls, as well as in a second cohort comprising of 74 healthy, non-pregnant control women, using a chemiluminometric sandwich immunoassay. Pro-NT was correlated to measures of obesity, hypertension, glucose and lipid metabolism, renal function, and inflammation. Mean ± standard deviation of circulating Pro-NT levels were not significantly different in women with GDM (100.2 ± 75.7 pmol/l) as compared to healthy, pregnant controls (103.2 ± 37.4 pmol/l) and healthy, non-pregnant female controls (105.9 ± 38.9 pmol/l) (p = 0.661). Homeostasis model assessment of insulin resistance (HOMA-IR) and creatinine positively correlated with serum Pro-NT in multivariate regression analysis. In contrast, free fatty acids (FFA) were inversely correlated with circulating Pro-NT. Results sustained adjustment for pregnancy status.

CONCLUSIONS

Circulating Pro-NT is not independently associated with GDM, but is with HOMA-IR, creatinine, and FFA even after adjustment for pregnancy status.

Leptin decreases circulating inflammatory IL-6 and MCP-1 in mice

Leptin influences inflammation and immune response. Dose-dependent effects of leptin on biomarkers of inflammation have not been studied in vivo, so far. Leptin-deficient low-density lipoprotein receptor (LDLR) knockout (LDLR^-/- ;ob/ob) female mice were treated with three different leptin doses or saline for 12 weeks. The effect of leptin on plasma interleukin (IL)-6 and monocyte chemoattractant protein (MCP)-1 concentrations and Il-6 and Mcp-1 mRNA expression in vivo were assessed. Macrophage infiltration in epididymal adipose tissue (epiAT) after leptin treatment was determined by quantitative immunohistochemical analysis. Aortic root atherosclerotic lesions were analyzed by oil red O staining. Mean plasma IL-6 and MCP-1 decreased significantly in the 3.0 mg/kg BW/day group as compared to control mice (both P < 0.01). Messenger RNA expression of Il-6 and Mcp-1 was significantly down-regulated by leptin treatment in different adipose tissues in vivo. Characteristic crown-like structures formed by adipose tissue macrophages were significantly reduced by leptin treatment in epiAT. Recombinant leptin dose-dependently diminished plaque area in the aortic root. Leptin administration within the subphysiological to physiological range diminishes circulating pro-inflammatory IL-6 and MCP-1. Reduction of Il-6 and Mcp-1 gene expression in adipose tissue, as well as decreased adipose tissue macrophage infiltration might contribute. © 2018 BioFactors, 45(1):43-48, 2019.

The Pituitary-Thyroid Axis and Prolactin Secretion in Hemodialysis Patients in Two Endemic Regions of Eastern Germany

Introduction Endocrine disorders of the pituitary axes are frequent in patients with hemodialysis (CKD5D). The aim of this multicenter study (Leipzig (L), Quedlinburg and Blankenburg in the Harz region (Hz)) in CKD5D patients was to evaluate influences of CKD5D related factors, morphological and biochemical parameters, and serum iodine and prolactin concentrations on the pituitary-thyroid axis.

Patients and Methods 170 patients (L n=58; Hz n=112) were included in this prospective, non-interventional, cross-sectional study. Mann-Whitney-U-test and bivariate correlation analyses with Spearman-Rho test (r correlation coefficient) were used in statistical analysis.

Results TSH was higher in patients with prolactin concentrations>370 mIU/l (p=0.013), in patients with high flux membranes (p=0.0013) and in patients with longer dialysis vintage (p=0.04). Median iodine serum concentrations were slightly elevated in the Leipzig cohort (p=0.001) and correlated with fT4 (p<0.001, r=0.43) and albumin (p=0.001, r=0.245) but not with morphological signs. Albumin was correlated with fT3 (p<0.001, r=0.339) and fT4 (p<0.001, r=0.421). Prolactin was correlated with residual excretion rate (p=0.001, r=- 0.303) and thyroid volume (p=0.027, r=0.217).

Conclusions In the assessment of the thyroid status in CKD5D patients, the synopsis of the clinical and nutritional status, comorbidities, ultrasound of the thyroid gland and laboratory results is necessary for further intervention with hormone replacement. Standardized reference values of the pituitary-thyroid axis should be critically evaluated and are still lacking in CKD5D.

Relationship Between 12 Adipocytokines and Distinct Components of the Metabolic Syndrome

OBJECTIVE

Adipose tissue-derived signals potentially link obesity and adipose tissue dysfunction with metabolic and cardiovascular diseases. Although some adipocytokines have been closely related to metabolic and cardiovascular traits, it is unknown which adipocytokine or adipocytokine clusters serve as meaningful markers of metabolic syndrome (MS) components. Therefore, this study investigated the associations of 12 adipocytokines with components of the MS to identify the most relevant cytokines potentially related to specific metabolic profiles.

RESEARCH DESIGN AND METHODS

Twelve cytokines [adiponectin, adipocyte fatty acid-binding protein (AFABP), angiopoietin-related growth factor, chemerin, fibroblast growth factor (FGF) 19, FGF21, FGF23, insulin-like growth factor-1, interleukin 10, irisin, progranulin, and vaspin] were quantified in a cross-sectional cohort of 1046 subjects. Hypothesis-free cluster analysis, multivariate regression analyses with parameters of the MS, and discriminant analysis were performed to assess associations and the relative importance of each cytokine for reflecting MS and its components.

RESULTS

Among the studied adipocytokines, adiponectin, AFABP, chemerin, and FGF21 showed the strongest associations with MS and several MS components in discriminant analyses and multiple regression models. For certain metabolic components, these adipocytokines were better discriminators than routine metabolic markers. Other cytokines investigated in the present cohort are less able to distinguish between metabolically healthy and unhealthy subjects.

CONCLUSIONS

Adiponectin, AFABP, chemerin, and FGF21 showed the strongest associations with MS components in a general population, suggesting that adverse adipose tissue function is a major contributor to these metabolic abnormalities. Future prospective studies should address the question whether these adipocytokines can predict the development of metabolic disease states.

Effects of Sex Hormone Treatment on the Metabolic Syndrome in Transgender Individuals: Focus on Metabolic Cytokines

CONTEXT

Hormonal treatment in transgender persons affects many components of the metabolic syndrome (MS).

OBJECTIVE

To determine the role of direct hormonal effects, changes in metabolic cytokines, and body composition on metabolic outcomes.

DESIGN, SETTING, AND PARTICIPANTS

24 transwomen and 45 transmen from the European Network for the Investigation of Gender Incongruence were investigated at baseline and after 12 months of hormonal therapy.

OUTCOME MEASURES

Best predictors for changes in components of MS, applying least absolute shrinkage and selection operator regression.

RESULTS

In transwomen, a decrease in triglyceride levels was best explained by a decrease in fat mass and an increase in fibroblast growth factor 21 (FGF-21); the decrease in total and low-density lipoprotein cholesterol levels was principally due to a decrease in resistin. A decrease in high-density lipoprotein cholesterol depended on an inverse association with fat mass. In contrast, in transmen, an increase in low-density lipoprotein cholesterol was predicted by a decrease in FGF-21 and an increase in the waist/hip ratio; a decrease in the high-density lipoprotein/total cholesterol ratio depended on a decline in adiponectin levels. In transwomen, worsened insulin resistance and increased early insulin response seemed to be due to a direct treatment effect; however, improvements in hepatic insulin sensitivity in transmen were best predicted by a positive association with chemerin, resistin, and FGF-21 and were inversely related to changes in the waist/hip ratio and leptin and adipocyte fatty acid-binding protein levels.

CONCLUSIONS

The effects of hormonal therapy on different components of the MS are sex-specific and involve a complex interplay of direct hormonal effects, changes in body composition, and metabolic cytokine secretion.