Anesthesia and bariatric surgery gut preparation alter plasma acylcarnitines reflective of mitochondrial fat and branched-chain amino acid oxidation

Skin fibroblast metabolomic profiling reveals that lipid dysfunction predicts the severity of Friedreich's ataxia

Friedreich's ataxia (FRDA) is an autosomal recessive neurodegenerative disorder caused by a triplet guanine-adenine-adenine (GAA) repeat expansion in intron 1 of the FXN gene, which leads to decreased levels of the frataxin protein. Frataxin is involved in the formation of iron-sulfur (Fe-S) cluster prosthetic groups for various metabolic enzymes. To provide a better understanding of the metabolic status of patients with FRDA, here we used patient-derived fibroblast cells as a surrogate tissue for metabolic and lipidomic profiling by liquid chromatography-high resolution mass spectrometry. We found elevated HMG-CoA and β-hydroxybutyrate-CoA levels, implying dysregulated fatty acid oxidation, which was further demonstrated by elevated acyl-carnitine levels. Lipidomic profiling identified dysregulated levels of several lipid classes in FRDA fibroblast cells when compared with non-FRDA fibroblast cells. For example, levels of several ceramides were significantly increased in FRDA fibroblast cells; these results positively correlated with the GAA repeat length and negatively correlated with the frataxin protein levels. Furthermore, stable isotope tracing experiments indicated increased ceramide synthesis, especially for long-chain fatty acid-ceramides, in FRDA fibroblast cells compared with ceramide synthesis in healthy control fibroblast cells. In addition, PUFA-containing triglycerides and phosphatidylglycerols were enriched in FRDA fibroblast cells and negatively correlated with frataxin levels, suggesting lipid remodeling as a result of FXN deficiency. Altogether, we demonstrate patient-derived fibroblast cells exhibited dysregulated metabolic capabilities, and their lipid dysfunction predicted the severity of FRDA, making them a useful surrogate to study the metabolic status in FRDA.

The SGLT2 Inhibitor Dapagliflozin Increases the Oxidation of Ingested Fatty Acids to Ketones in Type 2 Diabetes

OBJECTIVE

To investigate the mechanism for increased ketogenesis following treatment with the SGLT2 inhibitor dapagliflozin in people with type 2 diabetes.

RESEARCH DESIGN AND METHODS

The design was a double-blind, placebo-controlled, crossover study with a 4-week washout period. Participants received dapagliflozin or placebo in random order for 4 weeks. After each treatment, they ingested 30 mL of olive oil containing [U-13C]palmitate to measure ketogenesis, with blood sampling for 480 min. Stable isotopes of glucose and glycerol were infused to measure glucose flux and lipolysis, respectively, at 450-480 min.

RESULTS

Glucose excretion rate was higher and peripheral glucose uptake lower with dapagliflozin than placebo. Plasma β-hydroxybutyrate (BOHB) concentrations and [13C2]BOHB concentrations were higher and glucose concentrations lower with dapagliflozin than placebo. Nonesterified fatty acids (NEFAs) were higher with dapagliflozin at 300 and 420 min, but lipolysis at 450-480 min was not different. Triacylglycerol at all time points and endogenous glucose production rate at 450-480 min were not different between treatments.

CONCLUSIONS

The increase in ketone enrichment from the ingested palmitic acid tracer suggests that meal-derived fatty acids contribute to the increase in ketones during treatment with dapagliflozin. The increase in BOHB concentration with dapagliflozin occurred with only minimal changes in plasma NEFA concentration and no change in lipolysis. This finding suggests a metabolic switch to increase ketogenesis within the liver.

Perioperative changes in the plasma metabolome of patients receiving general anesthesia for pancreatic cancer surgery

Background: Modern anesthesia strives to offer personalized concepts to meet the patient’s individual needs in sight of clinical outcome. Still, little is known about the impact of anesthesia on the plasma metabolome, although many metabolites have been shown to modulate the function of various immune cells, making it particularly interesting in the context of oncological surgery. In this study longitudinal dynamics in the plasma metabolome during general anesthesia in patients undergoing pancreatic surgery were analyzed.

Materials and Methods: Prospective, observational study with 10 patients diagnosed with pancreatic (pre-) malignancy and subjected to elective resection surgery under general anesthesia. Plasma metabolites (n = 630) were quantified at eight consecutive perioperative timepoints using mass spectrometry-based targeted metabolomics.

Results: 39 metabolites significantly changed during the perioperative period. Tryptophan concentrations decreased by 45% with the maximum decrease after anesthesia induction (p = 6.24E-07), while taurine synthesis increased (p = 1.46E-04). Triacylglycerides and lysophosphatidylcholines were significantly reduced with increased liberation of free monounsaturated fatty acids (p = 0.03). Carnitine levels decreased significantly (p = 9.30E-04).

Conclusions: The major finding of this study was perioperative tryptophan depletion and increased taurine synthesis. Both are essential for immune cell function and are therefore of significant interest for perioperative management. Further studies are needed to identify influencing anesthetic factors.

Metabolic Effects of Gastric Bypass Surgery: Is It All About Calories?

Bariatric surgery is an efficient method to induce weight loss and also, frequently, remission of type 2 diabetes (T2D). Unpaired studies have shown bariatric surgery and dietary interventions to differentially affect multiple hormonal and metabolic parameters, suggesting that bariatric surgery causes T2D remission at least partially via unique mechanisms. In the current study, plasma metabolite profiling was conducted in patients with (n = 10) and without T2D (n = 9) subjected to Roux-en-Y gastric bypass surgery (RYGB). Mixed-meal tests were conducted at baseline, after the presurgical very-low-calorie diet (VLCD) intervention, immediately after RYGB, and after a 6-week recovery period. Thereby, we could compare fasted and postprandial metabolic consequences of RYGB and VLCD in the same patients. VLCD yielded a pronounced increase in fasting acylcarnitine levels, whereas RYGB, both immediately and after a recovery period, resulted in a smaller but opposite effect. Furthermore, we observed profound changes in lipid metabolism following VLCD but not in response to RYGB. Most changes previously associated with RYGB were found to be consequences of the presurgical dietary intervention. Overall, our results question previous findings of unique metabolic effects of RYGB and suggest that the effect of RYGB on the metabolite profile is mainly attributed to caloric restriction.

Metabolomics Study Revealing the Potential Risk and Predictive Value of Fragmented QRS for Acute Myocardial Infarction

Patients with nonobstructive coronary artery disease (NOCAD) have high risk associated with acute myocardial infarction (AMI), and fragmented QRS (fQRS) has a predictive value of AMI after percutaneous coronary intervention (PCI). A cohort of 254 participants were recruited including 136 NOCAD and 118 AMI patients from Xi'an No. 1 Hospital. Comprehensive metabolomics was performed by UPLC-Q/TOF-MS with multivariate statistical analyses. Hazard ratios were measured to discriminate the prognostic in AMI after PCI between differential metabolites and fQRS. OPLS-DA separated metabolites from NOCAD and AMI in serum. A total of 23 differential metabolites were identified between NOCAD and AMI. In addition, four differential metabolites, namely, acetylglycine, threoninyl-glycine, glutarylglycine, and nonanoylcarnitine, were identified between fQRS and non-fQRS in AMI. The hazard ratios demonstrate that the metabolites were associated with the risk of cardiac death, recurrent angina, readmissions, and major adverse cardiovascular events, which may clarify the mechanism of fQRS as a predictor in the prognostic of AMI after PCI. This study identified novel differential metabolites to distinguish the difference from NOCAD to AMI and clarify the mechanism of fQRS in prognostic of AMI after PCI, which may provide novel insights into potential risks and prognostic of AMI.