Characteristics of pulmonary artery strain assessed by cardiovascular magnetic resonance imaging and associations with metabolomic pathways in human ageing.

Background: Pulmonary artery (PA) strain is associated with structural and functional alterations of the vessel and is an independent predictor of cardiovascular events. The relationship of PA strain to metabolomics in participants without cardiovascular disease is unknown. Methods: In the current study, community-based older adults, without known cardiovascular disease, underwent simultaneous cine cardiovascular magnetic resonance (CMR) imaging, clinical examination, and serum sampling. PA global longitudinal strain (GLS) analysis was performed by tracking the change in distance from the PA bifurcation to the pulmonary annular centroid, using standard cine CMR images. Circulating metabolites were measured by cross-sectional targeted metabolomics analysis. Results: Among n = 170 adults (mean age 71 ± 6.3 years old; 79 women), mean values of PA GLS were 16.2 ± 4.4%. PA GLS was significantly associated with age (ß = -0.13, P = 0.017), heart rate (ß = -0.08, P = 0.001), dyslipidemia (ß = -2.37, P = 0.005), and cardiovascular risk factors (ß = -2.49, P = 0.001). Alanine (ß = -0.007, P = 0.01) and proline (ß = -0.0009, P = 0.042) were significantly associated with PA GLS after adjustment for clinical risk factors. Medium and long-chain acylcarnitines were significantly associated with PA GLS (C12, P = 0.027; C12-OH/C10-DC, P = 0.018; C14:2, P = 0.036; C14:1, P = 0.006; C14, P = 0.006; C14-OH/C12-DC, P = 0.027; C16:3, P = 0.019; C16:2, P = 0.006; C16:1, P = 0.001; C16:2-OH, P = 0.016; C16:1-OH/C14:1-DC, P = 0.028; C18:1-OH/C16:1-DC, P = 0.032). Conclusion: By conventional CMR, PA GLS was associated with aging and vascular risk factors among a contemporary cohort of older adults. Metabolic pathways involved in PA stiffness may include gluconeogenesis, collagen synthesis, and fatty acid oxidation.

Longitudinal aortic strain, ventriculo-arterial coupling and fatty acid oxidation: novel insights into human cardiovascular aging.

Aging-induced aortic stiffness has been associated with altered fatty acid metabolism. We studied aortic stiffness using cardiac magnetic resonance (CMR)-assessed ventriculo-arterial coupling (VAC) and novel aortic (AO) global longitudinal strain (GLS) combined with targeted metabolomic profiling. Among community older adults without cardiovascular disease, VAC was calculated as aortic pulse wave velocity (PWV), a marker of arterial stiffness, divided by left ventricular (LV) GLS. AOGLS was the maximum absolute strain measured by tracking the phasic distance between brachiocephalic artery origin and aortic annulus. In 194 subjects (71 ± 8.6 years; 88 women), AOGLS (mean 5.6 ± 2.1%) was associated with PWV (R = -0.3644, p < 0.0001), LVGLS (R = 0.2756, p = 0.0001) and VAC (R = -0.3742, p <0.0001). Stiff aorta denoted by low AOGLS <4.26% (25th percentile) was associated with age (OR 1.13, 95% CI 1.04-1.24, p = 0.007), body mass index (OR 1.12, 95% CI 1.01-1.25, p = 0.03), heart rate (OR 1.04, 95% CI 1.01-1.06, p = 0.011) and metabolites of medium-chain fatty acid oxidation: C8 (OR 1.005, p = 0.026), C10 (OR 1.003, p = 0.036), C12 (OR 1.013, p = 0.028), C12:2-OH/C10:2-DC (OR 1.084, p = 0.032) and C16-OH (OR 0.82, p = 0.006). VAC was associated with changes in long-chain hydroxyl and dicarboxyl carnitines. Multivariable models that included acyl-carnitine metabolites, but not amino acids, significantly increased the discrimination over clinical risk factors for prediction of AOGLS (AUC [area-under-curve] 0.73 to 0.81, p = 0.037) and VAC (AUC 0.78 to 0.87, p = 0.0044). Low AO GLS and high VAC were associated with altered medium-chain and long-chain fatty acid oxidation, respectively, which may identify early metabolic perturbations in aging-associated aortic stiffening. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02791139.

Plasma Tryptophan-Kynurenine Pathway Metabolites and Risk for Progression to End-Stage Kidney Disease in Patients With Type 2 Diabetes.

OBJECTIVE: We sought to study the associations between plasma metabolites in the tryptophan-kynurenine pathway and the risk of progression to end-stage kidney disease (ESKD) in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: Plasma tryptophan, kynurenine, 3-hydroxykynurenine, kynurenic acid, and xanthurenic acid concentrations were measured in discovery (n = 1,915) and replication (n = 346) cohorts. External validation was performed in Chronic Renal Insufficiency Cohort (CRIC) participants with diabetes (n = 1,312). The primary outcome was a composite of incident ESKD (progression to estimated glomerular filtration rate [eGFR] <15 mL/min/1.73 m2, sustained dialysis, or renal death). The secondary outcome was annual eGFR decline. RESULTS: In the discovery cohort, tryptophan was inversely associated with risk for ESKD, and kynurenine-to-tryptophan ratio (KTR) was positively associated with risk for ESKD after adjustment for clinical risk factors, including baseline eGFR and albuminuria (adjusted hazard ratios [HRs] 0.62 [95% CI 0.51, 0.75] and 1.48 [1.20, 1.84] per 1 SD). High levels of kynurenic acid and xanthurenic acid were associated with low risks of ESKD (0.74 [0.60, 0.91] and 0.74 [0.60, 0.91]). Consistently, high levels of tryptophan, kynurenic acid, and xanthurenic acid were independently associated with a slower eGFR decline, while a high KTR was predictive of a faster eGFR decline. Similar outcomes were obtained in the replication cohort. Furthermore, the inverse association between kynurenic acid and risk of ESKD was externally validated in CRIC participants with diabetes (adjusted HR 0.78 [0.65, 0.93]). CONCLUSIONS: Accelerated catabolism of tryptophan in the kynurenine pathway may be involved in progressive loss of kidney function. However, shunting the kynurenine pathway toward the kynurenic acid branch may potentially slow renal progression.

Lipidomics Workflow for Analyzing Lipid Profiles Using Multiple Reaction Monitoring (MRM) in Liver Homogenate of Mice with Non-alcoholic Steatohepatitis (NASH).

Non-alcoholic steatohepatitis (NASH) is a condition characterized by inflammation and hepatic injury/fibrosis caused by the accumulation of ectopic fats in the liver. Recent advances in lipidomics have allowed the identification and characterization of lipid species and have revealed signature patterns of various diseases. Here, we describe a lipidomics workflow to assess the lipid profiles of liver homogenates taken from a NASH mouse model. The protocol described below was used to extract and analyze the metabolites from the livers of mice with NASH by liquid chromatography-mass spectrometry (LC-MS); however, it can be applied to other tissue homogenate samples. Using this method, over 1,000 species of lipids from five classes can be analyzed in a single run on the LC-MS. Also, partial elucidation of the identity of neutral lipid (triacylglycerides and diacylglycerides) aliphatic chains can be performed with this simple LC-MS setup. Key features Over 1,000 lipid species (sphingolipids, cholesteryl esters, neutral lipids, phospholipids, fatty acids) are analyzed in one run. Analysis of liver lipids in non-alcoholic steatohepatitis (NASH) mouse model. Normal-phase chromatography coupled to a triple quadrupole mass spectrometer.

Gut-brain axis through the lens of gut microbiota and their relationships with Alzheimer's disease pathology: Review and recommendations.

Alzheimer's disease (AD) is a neurodegenerative disorder that affects millions of people worldwide. Growing evidence suggests that the gut microbiome (GM) plays a pivotal role in the pathogenesis of AD through the microbiota-gut-brain axis (MGB). Alterations in GM composition and diversity have been observed in both animal models and in human patients with AD. GM dysbiosis has been implicated in increased intestinal permeability, blood-brain barrier (BBB) impairment, neuroinflammation and the development of hallmarks of AD. Further elucidation of the role of GM in AD could pave way for the development of holistic predictive methods for determining AD risk and progression of disease. Furthermore, accumulating evidence suggests that GM modulation could alleviate adverse symptoms of AD or serve as a preventive measure. In addition, increasing evidence shows that Type 2 Diabetes Mellitus (T2DM) is often comorbid with AD, with common GM alterations and inflammatory response, which could chart the development of GM-related treatment interventions for both diseases. We conclude by exploring the therapeutic potential of GM in alleviating symptoms of AD and in reducing risk. Furthermore, we also propose future directions in AD research, namely fecal microbiota transplantation (FMT) and precision medicine.

The Utility of Amino Acid Metabolites in the Diagnosis of Major Depressive Disorder and Correlations with Depression Severity.

Major depressive disorder (MDD) is a highly prevalent and disabling condition with a high disease burden. There are currently no validated biomarkers for the diagnosis and treatment of MDD. This study assessed serum amino acid metabolite changes between MDD patients and healthy controls (HCs) and their association with disease severity and diagnostic utility. In total, 70 MDD patients and 70 HCs matched in age, gender, and ethnicity were recruited for the study. For amino acid profiling, serum samples were analysed and quantified by liquid chromatography-mass spectrometry (LC-MS). Receiver-operating characteristic (ROC) curves were used to classify putative candidate biomarkers. MDD patients had significantly higher serum levels of glutamic acid, aspartic acid and glycine but lower levels of 3-Hydroxykynurenine; glutamic acid and phenylalanine levels also correlated with depression severity. Combining these four metabolites allowed for accurate discrimination of MDD patients and HCs, with 65.7% of depressed patients and 62.9% of HCs correctly classified. Glutamic acid, aspartic acid, glycine and 3-Hydroxykynurenine may serve as potential diagnostic biomarkers, whereas glutamic acid and phenylalanine may be markers for depression severity. To elucidate the association between these indicators and clinical features, it is necessary to conduct additional studies with larger sample sizes that involve a spectrum of depressive symptomatology.

Adverse cardiovascular and metabolic perturbations among older women: 'fat-craving' hearts.

BACKGROUND: Despite known sex-based differences in cardiovascular aging, differences in aging biology are poorly understood. We hypothesize that circulating metabolites studied cross-sectionally with cardiac aging may be associated with cardiovascular changes that distinguish cardiac aging in women. METHODS: A population-based cohort of community men and women without cardiovascular disease from Singapore underwent detailed clinical and echocardiography examinations. Cross-sectional associations between cardiac functional characteristics and metabolomics profiles were examined. RESULTS: Five hundred sixty-seven adults (48.9% women) participated. Women were younger (72 ± 4.4 years vs 73 ± 4.3 years, p = 0.022), had lower diastolic blood pressures (71 ± 11.0 mmHg vs 76 ± 11.2 mmHg, p < 0.0001, and less likely to have diabetes mellitus (18.0% vs 27.6%, p = 0.013) and smoking (3.8% vs 34.5%, p < 0.001). Body mass indices were similar (24 ± 3.8 kg/m2 vs 24 ± 3.4 kg/m2, p = 0.29), but women had smaller waist circumferences (81 ± 10.1 cm vs 85 ± 9.2 cm, p < 0.001). Women had a significantly higher E/e' ratios (10.9 ± 3.4 vs 9.9 ± 3.3, p = 0.007) and mitral A peak (0.86 ± 0.2 m/s vs 0.79 ± 0.2 m/s, p < 0.001) than men. Among women, lower E/e' ratio was associated with higher levels of C16 (OR 1.019, 95%CI 1.002-1.036, p = 0.029), C16:1 (OR 1.06, 95%CI 1.006-1.118, p = 0.028), serine (OR 1.019, 95%CI 1.002-1.036, p = 0.025), and histidine (OR 1.045, 95%CI 1.013-1.078, p = 0.006). Lower mitral A peak was associated with higher levels of histidine (OR 1.039, 95%CI 1.009-1.070, p = 0.011), isoleucine (OR 1.013, 95%CI 1.004-1.021, p = 0.004), and C20 (OR 1.341, 95%CI 1.067-1.684, p = 0.012). CONCLUSION: Impairments in diastolic functions were more frequent among older women compared to men, despite lower prevalence of vascular risk factors and preserved cardiac structure. Cardiac aging in women correlated with metabolites involved in fatty acid oxidation and tricyclic acid cycle fuelling.

Sensitive ex vivo human skin transdermal assay testing method with mass spectrometric analysis for cosmetics application.

BACKGROUND: Cosmetics manufacturers are focused on cosmetic delivery systems into the skin, but the level of diffusion of the systems in the skin tissues is not well understood. The current methods, such as Franz diffusion, assess analyte diffusion in the whole skin or artificial membranes, which has limitations for understanding skin delivery systems. AIMS: Our study aimed to create a transdermal delivery method which is based on dermal-epidermal separation of human skin, allowing us to assess each layer of skin separately for its efficacy. MATERIALS AND METHODS: During the experiment, resveratrol was used as the target analyte by applying it to the skin and then separating it into dermis and epidermis. Each layer is treated individually and subjected to a high-resolution mass spectrometry analysis to detect resveratrol levels. As a result, the efficiency of resveratrol diffusion in the dermal and epidermal layers of the skin can be evaluated. RESULTS: We found that resveratrol was detected in both the dermal and epidermal layers using our method. CONCLUSIONS: Hence, we developed a sensitive method for transdermal delivery testing that can be used to evaluate skin delivery systems for cosmetic or pharmaceutical purposes.

Plasma acylcarnitines as metabolic signatures of declining health-related quality of life measure in community-dwelling older adults: a combined cross-sectional and longitudinal pilot study.

BACKGROUND: Health-related quality of life (HRQoL) measures are predictors of adverse health outcomes in older adults. Studies have demonstrated cross-sectional associations between HRQoL measures and blood-based biochemical markers. Acylcarnitines (ACs) are a class of metabolites generated in the mitochondria and are predictive of multiple geriatric syndromes. Changes in ACs reflect alterations in central carbon metabolic pathways. However, the prospective relationship between plasma acylcarnitines and declining HRQoL has not been examined. This study aimed to investigate both cross-sectional and longitudinal associations of baseline ACs with baseline and declining EuroQol-5 Dimension/ EuroQol Visual Analogue Scale (EQ-5D/ EQ-VAS) in community-dwelling older adults. METHODS: 120 community-dwelling older adults with EQ-5D/ EQ-VAS measurements at baseline and follow-up were included. We quantified ACs at baseline using targeted plasma metabolomics profiling. Multivariate regressions were performed to examine cross-sectional and longitudinal associations between the measures. RESULTS: Cross-sectionally, ACs showed no significant associations with either EQ-5D index or EQ-VAS scores. Longitudinally, multiple baseline short-chain ACs were significantly and inversely associated with declining EQ-5D index score, explaining up to 8.5% of variance in the decline. CONCLUSIONS: Within a cohort of community-dwelling older adults who had high HRQoL at baseline, we showed that short-chain acylcarnitines are independent predictors of declining HRQoL. These findings reveal a novel association between central carbon metabolic pathways and declining HRQoL. Notably, dysregulation in mitochondrial central carbon metabolism could be detected prior to clinically important decline in HRQoL, providing the first evidence of objective biomarkers as novel predictors to monitor HRQoL in non-pharmacological interventions and epidemiology.

Amino acid profile of skeletal muscle loss in type 2 diabetes: Results from a 7-year longitudinal study in asians.

AIMS: Little is known about pathophysiology of sarcopenia in diabetes. We aimed to study amino acid profile associated with skeletal muscle mass loss longitudinally in Type 2 Diabetes Mellitus (T2DM). METHODS: This is a prospective study of 1140 patients aged 56.6 ± 10.6 years from the SMART2D cohort. Skeletal muscle mass was measured using bio-impedance analysis at baseline and follow-up. Amino acids were measured by mass spectrometry. RESULTS: Over a period of up to 7.9 years, 43.9% experienced skeletal muscle mass loss. Lower baseline valine, leucine and isoleucine levels were associated with decreased skeletal muscle mass index (SMI) with corresponding coefficient 0.251(95 %CI 0.009 to 0.493), 0.298(95 %CI 0.051 to 0.544)) and 0.366(95 %CI 0.131 to 0.600). Higher baseline valine, leucine, isoleucine, alanine and tryptophan levels were associated with reduced odds of muscle mass loss with corresponding odds ratio (OR)0.797 (95 %CI 0.690 to 0.921), 0.825 (95 %CI 0.713 to 0.955), 0.826 (95 %CI 0.718-0.950), 0.847 (95 %CI 0.739-0.969) and 0.835 (95 %CI 0.720-0.979). CONCLUSION: The branched-chain amino acids valine, leucine and isoleucine were positively associated with change in SMI and reduced odds of muscle mass loss longitudinally. Further studies should be conducted to elucidate the pathophysiological mechanisms underlying the relationship between these amino acids and muscle mass loss in T2DM.

The Kynurenine Pathway in Acute Kidney Injury and Chronic Kidney Disease.

BACKGROUND: The kynurenine pathway (KP) is the major catabolic pathway for tryptophan degradation. The KP plays an important role as the sole de novo nicotinamide adenine dinucleotide (NAD+) biosynthetic pathway in normal human physiology and functions as a counter-regulatory mechanism to mitigate immune responses during inflammation. Although the KP has been implicated in a variety of disorders including Huntington's disease, seizures, cardiovascular disease, and osteoporosis, its role in renal diseases is seldom discussed. SUMMARY: This review summarizes the roles of the KP and its metabolites in acute kidney injury (AKI) and chronic kidney disease (CKD) based on current literature evidence. Metabolomics studies demonstrated that the KP metabolites were significantly altered in patients and animal models with AKI or CKD. The diagnostic and prognostic values of the KP metabolites in AKI and CKD were highlighted in cross-sectional and longitudinal human observational studies. The biological impact of the KP on the pathophysiology of AKI and CKD has been studied in experimental models of different etiologies. In particular, the activation of the KP was found to confer protection in animal models of glomerulonephritis, and its immunomodulatory mechanism may involve the regulation of T cell subsets such as Th17 and regulatory T cells. Manipulation of the KP to increase NAD+ production or diversion toward specific KP metabolites was also found to be beneficial in animal models of AKI. Key Messages: KP metabolites are reported to be dysregulated in human observational and animal experimental studies of AKI and CKD. In AKI, the magnitude and direction of changes in the KP depend on the etiology of the damage. In CKD, KP metabolites are altered with the onset and progression of CKD all the way to advanced stages of the disease, including uremia and its related vascular complications. The activation of the KP and diversion to specific sub-branches are currently being explored as therapeutic strategies in these diseases, especially with regards to the immunomodulatory effects of certain KP metabolites. Further elucidation of the KP may hold promise for the development of biomarkers and targeted therapies for these kidney diseases.

Integration of the Cortical Haemodynamic Response Measured by Functional Near-Infrared Spectroscopy and Amino Acid Analysis to Aid in the Diagnosis of Major Depressive Disorder.

BACKGROUND: Major depressive disorder (MDD) is a debilitating condition with a high disease burden and medical comorbidities. There are currently few to no validated biomarkers to guide the diagnosis and treatment of MDD. In the present study, we evaluated the differences between MDD patients and healthy controls (HCs) in terms of cortical haemodynamic responses during a verbal fluency test (VFT) using functional near-infrared spectroscopy (fNIRS) and serum amino acid profiles, and ascertained if these parameters were correlated with clinical characteristics. METHODS: Twenty-five (25) patients with MDD and 25 age-, gender-, and ethnicity-matched HCs were recruited for the study. Real-time monitoring of the haemodynamic response during completion of a VFT was quantified using a 52-channel NIRS system. Serum samples were analysed and quantified by liquid chromatography-mass spectrometry for amino acid profiling. Receiver-operating characteristic (ROC) curves were used to classify potential candidate biomarkers. RESULTS: The MDD patients had lower prefrontal and temporal activation during completion of the VFT than HCs. The MDD patients had lower mean concentrations of oxy-Hb in the left orbitofrontal cortex (OFC), and lower serum histidine levels. When the oxy-haemoglobin response was combined with the histidine concentration, the sensitivity and specificity of results improved significantly from 66.7% to 73.3% and from 65.0% to 90.0% respectively, as compared to results based only on the NIRS response. CONCLUSIONS: These findings demonstrate the use of combination biomarkers to aid in the diagnosis of MDD. This technique could be a useful approach to detect MDD with greater precision, but additional studies are required to validate the methodology.

Amino acid differences between diabetic older adults and non-diabetic older adults and their associations with cardiovascular function.

BACKGROUND: Ageing and insulin resistant states such as diabetes mellitus frequently coexist and increase the risk of cardiovascular disease development among older adults. Here we investigate metabolic differences in amino acid profiles between ageing and diabetes mellitus, and their associations with cardiovascular function. METHODS: In a group of community older adults we performed echocardiography, cardiac magnetic resonance imaging as well as cross sectional and longitudinal metabolomics profiling based on current and archived sera obtained fifteen years prior to examination. RESULTS: We studied a total of 515 participants (women 50%, n = 255) with a mean age 73 (SD = 4.3) years. Diabetics had higher alanine (562 vs 448, p < 0.0001), higher glutamate (107 vs 95, p = 0.016), higher proline (264 vs 231, p = 0.008) and lower arginine (107 vs 117, p = 0.043), lower citrulline (30 vs 38, p = 0.006) levels (µM) compared to non-diabetics. Over time, changes in amino acid profiles differentiated diabetic older adults from non-diabetic older adults, with greater accumulation of alanine (p = 0.002), proline (p = 0.008) and (non-significant) trend towards greater accumulation of glycine (p = 0.057) among the older diabetics compared to the older non-diabetics. However, independent of diabetes status, amino acids were associated with cardiovascular functions in ageing, [archived valine (p = 0.011), leucine (p = 0.011), archived isoleucine (p = 0.0006), archived serine (p = 0.008), archived glycine (p = 0.006) methionine (p = 0.003)] which were associated with impairments in E/A ratio. CONCLUSION: Markers of branched chain amino acids and one ­carbon metabolism pathways were associated with changes in cardiovascular function in older adults regardless of diabetes status. However, nitrogen handling pathways were specifically altered among older adults with diabetes. These findings broaden our understanding into specific amino acid pathways that may be altered between diabetic and non-diabetic older adults, and their relevance to cardiovascular function in ageing. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02791139.

Effects of Vitex trifolia L. leaf extracts and phytoconstituents on cytokine production in human U937 macrophages.

BACKGROUND: Dysregulation of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß) form the basis of immune-mediated inflammatory diseases. Vitex trifolia L. is a medicinal plant growing in countries such as China, India, Australia and Singapore. Its dried ripe fruits are documented in Traditional Chinese Medicine to treat ailments like rhinitis and dizziness. Its leaves are used traditionally to treat inflammation-related conditions like rheumatic pain. OBJECTIVE: This study aimed to investigate the effects of V. trifolia leaf extracts prepared by different extraction methods (Soxhlet, ultrasonication, and maceration) in various solvents on cytokine production in human U937 macrophages, and identify phytoconstituents from the most active leaf extract. METHODS: Fresh leaves of V. trifolia were extracted using Soxhlet, ultrasonication, and maceration in hexane, dichloromethane, methanol, ethanol or water. Each extract was evaluated for its effects on TNF-α and IL-1ß cytokine production by enzyme-linked immunosorbent assay in lipopolysaccharide-stimulated human U937 macrophages. The most active extract was analyzed and further purified by different chemical and spectroscopic techniques. RESULTS: Amongst 14 different leaf extracts investigated, extracts prepared by ultrasonication in dichloromethane and maceration in ethanol were most active in inhibiting TNF-α and IL-1ß production in human U937 macrophages. Further purification led to the isolation of artemetin, casticin, vitexilactone and maslinic acid, and their effects on TNF-α and IL-1ß production were evaluated. We report for the first time that artemetin suppressed TNF-α and IL-1ß production. Gas chromatography-mass spectrometry analyses revealed the presence of eight other compounds. To the best of our knowledge, this is the first report of butylated hydroxytoluene, 2,4-di-tert-butylphenol, campesterol and maslinic acid in V. trifolia leaf extracts. CONCLUSIONS: In conclusion, leaf extracts of V. trifolia obtained using different solvents and extraction methods were successfully investigated for their effects on cytokine production in human U937 macrophages. The findings provide scientific evidence for the traditional use of V. trifolia leaves (a sustainable resource) and highlight the importance of conservation of medicinal plants as resources for drug discovery. Our results together with others suggest further investigation on V. trifolia and constituents to develop novel treatment strategies in immune-mediated inflammatory conditions is warranted.