Impaired Fatty Acid Metabolism Research Articles

Impaired Long-Chain Fatty Acid Metabolism in Carnitine Palmitoyltransferase II Knockout Mouse Leads to Chronic Pancreatitis

Background: To support high rates of protein synthesis, pancreatic acinar cells must generate large quantities of ATP. Mitochondrial dysfunction and impaired energy metabolism play a significant role in the development of pancreatitis. Patients with elevated plasma triglycerides are at increased risk for development of severe acute pancreatitis. Carnitine palmitoyltransferase II (CPT2) is required for importing and thus metabolizing long-chain fatty acids (LCFAs) in mitochondria. To inhibit LCFA metabolism, we utilized the CPT2acinarKO mouse to probe the consequences of impaired LCFA import on pancreatic function. Hypothesis: Loss of CPT2 causes an accumulation of long-chain acylcarnitines and disruption of the tissue acylcarnitine/free carnitine ratio which is thought to alter cellular function. Given acinar cells’ high metabolic requirement, impaired LCFA utilization would reduce energy production, secretory function, and alter pancreatic lipid composition. Methods: We generated mice lacking CPT2 specifically in acinar cells (CPT2acinarKO) by crossing tamoxifen-inducible, Elastase-Cre mice with CPT2 floxed mice. Mice were fed a high fat (60% kcal fat), low fat (10% kcal fat), or chow (14% kcal fat) diet for 12 weeks. Analysis of fat accumulation, edema, and fibrosis was performed with H&E and picrosirius staining. Mass Spec. lipid profiling was performed in pancreas and serum. Acinar cells were isolated from wildtype, CPT2 floxed, and CPT2acinarKO mice to assess secretory function, ATP levels, and necrosis via lactate dehydrogenase (LDH) release. Results: Histologic examination revealed CPT2acinarKO mice on all three diets displayed pancreatic fat accumulation. Strikingly, CPT2acinarKO mice fed a chow or low fat diet developed chronic pancreatitis with a 25% loss in pancreatic weight, immune cell infiltration, edema, and fibrosis. As anticipated, long-chain acylcarnitines were significantly elevated in CPT2acinarKO pancreas. Assessment of secretion in 2 weeks post tamoxifen cells revealed significantly reduced maximal (10 pM) and supramaximal (1 nM) cholecystokinin (CCK) stimulated amylase release as a percent of total cellular amylase. Acini isolated at 4 weeks post tamoxifen revealed significantly increased basal secretion and reduced maximal and supramaximal CCK stimulated amylase release. When normalized to cellular DNA, secretion was similar between CPT2acinarKO and CPT2 floxed acinar cells indicating CPT2acinarKO cells had reduced amylase levels. Wildtype acinar cells treated with unsaturated and saturated free fatty acid concentrations as low as 100 μM for 3 hours caused significant necrosis. CPT2acinarKO pancreas had significantly decreased ATP levels indicative of mitochondrial dysfunction. Conclusion: Loss of CPT2 in the pancreatic acinar cells impairs LCFA import, reduces ATP levels, disrupts the secretory pathway, promoting chronic pancreatitis. In contrast to other CPT2 knockout models, pancreatitis occurs independent of high fat feeding in CPT2acinarKO mice. Further investigation is needed to identify metabolic alterations leading to acinar damage and mitochondrial dysfunction following the loss of CPT2. UW-Madison Comprehensive Diabetes Center Pilot Grant. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Aging-Induced Reduction in Safflower Seed Germination via Impaired Energy Metabolism and Genetic Integrity Is Partially Restored by Sucrose and DA-6 Treatment.

Seed storage underpins global agriculture and the seed trade and revealing the mechanisms of seed aging is essential for enhancing seed longevity management. Safflower is a multipurpose oil crop, rich in unsaturated fatty acids that are at high risk of peroxidation as a contributory factor to seed aging. However, the molecular mechanisms responsible for safflower seed viability loss are not yet elucidated. We used controlled deterioration (CDT) conditions of 60% relative humidity and 50 °C to reduce germination in freshly harvested safflower seeds and analyzed aged seeds using biochemical and molecular techniques. While seed malondialdehyde (MDA) and fatty acid content increased significantly during CDT, catalase activity and soluble sugar content decreased. KEGG analysis of gene function and qPCR validation indicated that aging severely impaired several key functional and biosynthetic pathways including glycolysis, fatty acid metabolism, antioxidant activity, and DNA replication and repair. Furthermore, exogenous sucrose and diethyl aminoethyl hexanoate (DA-6) treatment partially promoted germination in aged seeds, further demonstrating the vital role of impaired sugar and fatty acid metabolism during the aging and recovery processes. We concluded that energy metabolism and genetic integrity are impaired during aging, which contributes to the loss of seed vigor. Such energy metabolic pathways as glycolysis, fatty acid degradation, and the tricarboxylic acid cycle (TCA) are impaired, especially fatty acids produced by the hydrolysis of triacylglycerols during aging, as they are not efficiently converted to sucrose via the glyoxylate cycle to provide energy supply for safflower seed germination and seedling growth. At the same time, the reduced capacity for nucleotide synthesis capacity and the deterioration of DNA repair ability further aggravate the damage to DNA, reducing seed vitality.

Oat-based postbiotics ameliorate high-sucrose induced liver injury and colitis susceptibility by modulating fatty acids metabolism and gut microbiota

High-sucrose (HS) consumption leads to metabolic disorders and increases susceptibility to colitis. Postbiotics hold great potentials in combating metabolic diseases and offer advantages in safety and processability, compared with living probiotics. We developed innovative oat-based postbiotics and extensively explored how they could benefit in rats with long-term high-sucrose consumption. The postbiotics fermented with Lactiplantibacillus plantarum (OF-1) and OF-5, the one fermented with the optimal selection of five probiotics (i.e., L. plantarum, Limosilactobacillus reuteri, Lacticaseibacillus rhamnosus, Lactobacillus acidophilus, and Bifidobacterium lactis) alleviated HS induced liver injury, impaired fatty acid metabolism and inflammation through activating AMPK/SREBP-1c pathways. Moreover, oat-based postbiotics restored detrimental effects of HS on fatty acid profiles in liver, as evidenced by the increases in polyunsaturated fatty acids and decreases in saturated fatty acids, with OF-5 showing most pronounced effects. Furthermore, oat-based postbiotics prevented HS exacerbated susceptibility to dextran sodium sulfate caused colitis and reconstructed epithelial tight junction proteins in colons. Oat-based postbiotics, in particular OF-5 notably remodeled gut microbiota composition, e.g., enriching the relative abundances of Akkermansia, Bifidobacterium, Alloprevotella and Prevotella, which may play an important role in the liver-colon axis responsible for improvements of liver functions and reduction of colitis susceptibility. The heat-inactivated probiotics protected against HS-induced liver and colon damage, but such effects were less pronounced compared with oat-based postbiotics. Our findings emphasize the great value of oat-based postbiotics as nutritional therapeutics to combat unhealthy diet induced metabolic dysfunctions.

Cardiometabolic health in adults born with very low birth weight—a sibling study

BackgroundPreterm survivors have increased risk for impaired cardiometabolic health. We assessed glucose regulation and cardiometabolic biomarkers in adult very low birth weight (VLBW, <1500 g) survivors, using siblings as controls.MethodsVLBW-participants were matched with term-born, same-sex siblings. At mean age 29.2 years (SD 3.9), 74 VLBW-adults and 70 siblings underwent a 2-h 75 g oral glucose tolerance test and blood tests for assessment of cardiometabolic biomarkers.ResultsOf participants, 23 (31%) VLBW and 11 (16%) sibling-controls met World Health Organization criteria for impaired glucose regulation (OR adjusted for age and sex 2.5, 95% CI: 1.1 to 5.8).Adjusting for age and sex, VLBW-participants showed 9.2% higher 2-h glucose (95% CI: 0.4% to 18.8%) than their siblings. Also, fasting (13.4%, −0.3% to 29.0%) and 2-h free fatty acids (15.6%, −2.4% to 36.9%) were higher in VLBW-participants. These differences were statistically significant only after further adjusting for confounders. No statistically significant differences were found regarding other measured biomarkers, including insulin resistance, atherogenic lipid profiles or liver tests.ConclusionsVLBW-adults showed more impaired fatty acid metabolism and glucose regulation. Differences in cardiometabolic biomarkers were smaller than in previous non-sibling studies. This may partly be explained by shared familial, genetic, or environmental factors.ImpactAt young adult age, odds for impaired glucose regulation were 3.4-fold in those born at very low birth weight, compared to same-sex term-born siblings.Taking into consideration possible unmeasured, shared familial confounders, we compared cardiometabolic markers in adults born preterm at very low birth weight with term-born siblings.Prematurity increased risk for impaired glucose regulation, unrelated to current participant characteristics, including body mass index.In contrast to previous studies, differences in insulin resistance were not apparent, suggesting that insulin resistance may partially be explained by factors shared between siblings. Also, common cardiometabolic biomarkers were similar within sibling pairs.

Androgen receptor coordinates muscle metabolic and contractile functions.

Androgens are anabolic steroid hormones that exert their function by binding to the androgen receptor (AR). We have previously established that AR deficiency in limb muscles impairs sarcomere myofibrillar organization and decreases muscle strength in male mice. However, despite numerous studies performed in men and rodents, the signalling pathways controlled by androgens via their receptor in skeletal muscles remain poorly understood. Male ARskm-/y (n=7-12) and female ARskm-/- mice (n=9), in which AR is selectively ablated in myofibres of musculoskeletal tissue, and male AR(i)skm-/y , in which AR is selectively ablated in post-mitotic skeletal muscle myofibres (n=6), were generated. Longitudinal monitoring of body weight, blood glucose, insulin, lipids and lipoproteins was performed, alongside metabolomic analyses. Glucose metabolism was evaluated in C2C12 cells treated with 5α-dihydrotestosterone (DHT) and the anti-androgen flutamide (n=6). Histological analyses on macroscopic and ultrastructural levels of longitudinal and transversal muscle sections were conducted. The transcriptome of gastrocnemius muscles from control and ARskm-/y mice was analysed at the age of 9weeks (P<0.05, 2138 differentially expressed genes) and validated by RT-qPCR analysis. The AR (4691 peaks with false discovery rate [FDR]<0.1) and H3K4me2 (47225 peaks with FDR<0.05) cistromes in limb muscles were determined in 11-week-old wild-type mice. We show that disrupting the androgen/AR axis impairs in vivo glycolytic activity and fastens the development of type 2 diabetes in male, but not in female mice. In agreement, treatment with DHT increases glycolysis in C2C12 myotubes by 30%, whereas flutamide has an opposite effect. Fatty acids are less efficiently metabolized in skeletal muscles of ARskm-/y mice and accumulate in cytoplasm, despite increased transcript levels of genes encoding key enzymes of beta-oxidation and mitochondrial content. Impaired glucose and fatty acid metabolism in AR-deficient muscle fibres is associated with 30% increased lysine and branched-chain amino acid catabolism, decreased polyamine biosynthesis and disrupted glutamate transamination. This metabolic switch generates ammonia (2-fold increase) and oxidative stress (30% increased H2 O2 levels), which impacts mitochondrial functions and causes necrosis in <1% fibres. We unravel that AR directly activates the transcription of genes involved in glycolysis, oxidative metabolism and muscle contraction. Our study provides important insights into diseases caused by impaired AR function in musculoskeletal system and delivers a deeper understanding of skeletal muscle pathophysiological dynamics that is instrumental to develop effective treatment for muscle disorders.

Targeted metabolomics reveals plasma biomarkers and metabolic alterations of the aging process in healthy young and older adults.

With the exponential growth in the older population in the coming years, many studies have aimed to further investigate potential biomarkers associated with the aging process and its incumbent morbidities. Age is the largest risk factor for chronic disease, likely due to younger individuals possessing more competent adaptive metabolic networks that result in overall health and homeostasis. With aging, physiological alterations occur throughout the metabolic system that contribute to functional decline. In this cross-sectional analysis, a targeted metabolomic approach was applied to investigate the plasma metabolome of young (21-40y; n = 75) and older adults (65y + ; n = 76). A corrected general linear model (GLM) was generated, with covariates of gender, BMI, and chronic condition score (CCS), to compare the metabolome of the two populations. Among the 109 targeted metabolites, those associated with impaired fatty acid metabolism in the older population were found to be most significant: palmitic acid (p < 0.001), 3-hexenedioic acid (p < 0.001), stearic acid (p = 0.005), and decanoylcarnitine (p = 0.036). Derivatives of amino acid metabolism, 1-methlyhistidine (p = 0.035) and methylhistamine (p = 0.027), were found to be increased in the younger population and several novel metabolites were identified, such as cadaverine (p = 0.034) and 4-ethylbenzoic acid (p = 0.029). Principal component analysis was conducted and highlighted a shift in the metabolome for both groups. Receiver operating characteristic analyses of partial least squares-discriminant analysis models showed the candidate markers to be more powerful indicators of age than chronic disease. Pathway and enrichment analyses uncovered several pathways and enzymes predicted to underlie the aging process, and an integrated hypothesis describing functional characteristics of the aging process was synthesized. Compared to older participants, the young group displayed greater abundance of metabolites related to lipid and nucleotide synthesis; older participants displayed decreased fatty acid oxidation and reduced tryptophan metabolism, relative to the young group. As a result, we offer a better understanding of the aging metabolome and potentially reveal new biomarkers and predicted mechanisms for future study.

The Role of L-Carnitine in Kidney Disease and Related Metabolic Dysfunctions

Kidney disease is associated with a wide variety of metabolic abnormalities that accompany the uremic state and the state of dialysis dependence. These include altered L-carnitine homeostasis, mitochondrial dysfunctions, and abnormalities in fatty acid metabolism. L-carnitine is essential for fatty acid metabolism and proper mitochondrial function. Deficiency in kidney disease and dialysis is caused by a reduction in endogenous renal synthesis, impaired fatty acid metabolism, a lower intake due to dietary restrictions, and nonselective clearance by the dialysis procedure. Free carnitine levels &lt;40 µmol/L in dialysis patients can lead to dialysis-related complications, such as anemia that is hyporesponsive to erythropoietin therapy, intradialytic hypotension, cardiovascular disease, and skeletal muscle dysfunction manifested as muscle weakness and fatigue. L-carnitine deficiency is also seen in acute kidney injury (AKI) resulting from trauma and/or ischemia, drugs such as cisplatin, and from infections such as covid. A persistent state of L-carnitine deficiency can further damage kidneys and lead to multi-organ failure. Carnitine supplementation has been shown to be safe and effective in improving kidney disease-related complications resulting from drug-induced toxicity, trauma, ischemic injury, infection, and dialysis, by replenishing adequate carnitine levels and rebalancing carnitine homeostasis. In this review, we will examine the protective role of L-carnitine in reducing cellular oxidative damage and maintaining mitochondrial function together with the clinical evidence for its potential use in the management of kidney disease.

Increased circulating uric acid aggravates heart failure via impaired fatty acid metabolism

BackgroundIncreased circulating uric acid (UA) concentration may disrupt cardiac function in heart failure patients, but the specific mechanism remains unclear. Here, we postulate that hyperuremia induces sterol regulatory element binding protein 1 (SREBP1), which in turn activate hepatic fatty acid biosynthesis response, leading to cardiac dysfunction.Methods and resultsIncreased circulating uric acid was observed in heart failure patients and inversely correlated to cardiac function. Besides, uric acid correlated to circulating lipids profile based on metabolomics in heart failure patients. Using cultured human hepatoellular carcinomas (HepG2) and Tg(myl7:egfp) zebrafish, we demonstrated that UA regulated fatty acid synthase (FASN) via SREBP1 signaling pathway, leading to FFA accumulation and impaired energy metabolism, which could be rescued via SREBP1 knockdown. In ISO treated zebrafish, UA aggravated heart failure via increased cardiovascular cavity size, decreased heart beats, pericardial edema and long-stretched heart deformation.ConclusionsOur findings suggest that UA-SREBP1-FASN signaling exacerbates cardiac dysfunction during FFA accumulation. Identification of this mechanism may help in treatment and prevention of heart failure.

Nicotinamide riboside rescues dysregulated glycolysis and fatty acid β-oxidation in a human hepatic cell model of Citrin deficiency.

Citrin Deficiency (CD) is an inborn error of metabolism caused by loss-of-function of the mitochondrial aspartate/glutamate transporter, CITRIN, which is involved in both the urea cycle and malate aspartate shuttle. Patients with CD develop hepatosteatosis and hyperammonemia but there is no effective therapy for CD. Currently, there are no animal models that faithfully recapitulate the human CD phenotype. Accordingly, we generated a CITRIN knockout HepG2 cell line using CRISPR/Cas 9 genome editing technology to study metabolic and cell signaling defects in CD. CITRIN KO cells showed increased ammonia accumulation, higher cytosolic NADH/NAD+ ratio and reduced glycolysis. Surprisingly, these cells showed impaired fatty acid metabolism and mitochondrial activity. CITRIN KO cells also displayed increased cholesterol and bile acid metabolism resembling those observed in CD patients. Remarkably, normalizing cytosolic NADH:NAD+ ratio by nicotinamide riboside (NR) increased glycolysis and fatty acid oxidation but had no effect on the hyperammonemia suggesting the urea cycle defect was independent of the aspartate/malate shuttle defect of CD. The correction of glycolysis and fatty acid metabolism defects in CITRIN KO cells by reducing cytoplasmic NADH:NAD+ levels suggests this may be a novel strategy to treat some of the metabolic defects of CD and other mitochondrial diseases.

Impaired white adipose tissue fatty acid metabolism in mice fed a high-fat diet worsened by arsenic exposure, primarily affecting retroperitoneal adipose tissue

Fatty acid (FA) metabolism dysfunction of white adipose tissue (WAT) underlies obesity and insulin resistance in response to high calorie intake and/or endocrine-disrupting chemicals (EDCs), among other factors. Arsenic is an EDC that has been associated with metabolic syndrome and diabetes. However, the combined effect of a high-fat diet (HFD) and arsenic exposure on WAT FA metabolism has been little studied.FA metabolism was evaluated in visceral (epididymal and retroperitoneal) and subcutaneous WAT of C57BL/6 male mice fed control or HFD (12 and 40% kcal fat, respectively) for 16 weeks together with an environmentally relevant chronic arsenic exposure through drinking water (100 μg/L) during the second half of the study.In mice fed HFD, arsenic potentiated the increase of serum markers of selective insulin resistance in WAT and fatty acid re-esterification and the decrease of the lipolysis index. Retroperitoneal was the WAT most affected, where the combination of arsenic and HFD in contrast to HFD, generated higher adipose weight, larger adipocytes, increased triglyceride content, and decreased fasting stimulated lipolysis evidenced by lower phosphorylation of HSL and perilipin. At the transcriptional level, arsenic in mice fed either diet downregulated genes involved in fatty acid uptake (LPL, CD36), oxidation (PPARα, CPT1), lipolysis (ADRß3) and glycerol transport (AQP7 and AQP9). Additionally, arsenic potentiated hyperinsulinemia induced by HFD, despite a slight increase in weight gain and food efficiency.Thus, the second hit of arsenic in sensitized mice by HFD worsens fatty acid metabolism impairment in WAT, mainly retroperitoneal, along with an exacerbated insulin resistance phenotype.

Mitochondrial Fatty Acid Beta-Oxidation Disorders in Children: Literature Review

Congenital mitochondrial fatty acid beta-oxidation disorders are a heterogeneous group of metabolic disorders characterized by impaired fatty acid metabolism in mitochondria. It results in central nervous system, skeletal muscle, cardiovascular system, and liver damage, as well as the development of nonketotic hypoglycemia. The age of disease manifestation and its severity range from severe (neonatal) to milder myopathic (adult) forms. The extension of the mass screening program in Russian Federation allows to detect these diseases during the first weeks of life. The availability of effective therapy for mitochondrial fatty acid beta-oxidation disorders, especially during early diagnosis, enables timely stabilization of the patient's condition and prevention of severe complications. Awareness of pediatricians, neonatologists, neurologists, and cardiologists about such diseases is the urgent task of modern pediatrics.

Characterization of the Cafeteria Diet as Simulation of the Human Western Diet and Its Impact on the Lipidomic Profile and Gut Microbiota in Obese Rats.

The obesity pandemic has been strongly associated with the Western diet, characterized by the consumption of ultra-processed foods. The Western lifestyle causes gut dysbiosis leading to impaired fatty acid metabolism. Therefore, this study aimed to evaluate shifts in gut microbiota and correlate these with serum fatty acid profiles in male Wistar rats fed a cafeteria diet. Ten male rats were fed with standard diet (CTL, n = 5) and cafeteria diet (CAF, n = 5) for fifteen weeks. Body weight and food intake were recorded once and three times per week, respectively. At the end of the study, fresh fecal samples were collected, tissues were removed, and serum samples were obtained for further analyses. Gut microbiota was analyzed by sequencing the V3-V4 region of 16S rRNA gene. Serum fatty acid profiles were fractioned and quantified via gas chromatography. The CAF diet induced an obese phenotype accompanied by impaired serum fatty acids, finding significantly higher proportions of total saturated fatty acids (SFAs) and C20:3 n-6, and lower C18:1 n-7 and C18:3 n-3 in the phospholipid (PL) fraction. Furthermore, circulating C10:0, total n-3 and n-7 decreased and total monounsaturated fatty acids (MUFAs), including oleic acid C18:1 n-9, increased in the cholesterol ester (CE) fraction. The obesity metabotype may be mediated by gut dysbiosis caused by a cafeteria diet rich in C16:0, C18:0, C18:1 n-9 and C18:2 n-6 fatty acids resulting in a 34:1 omega-6/omega-3 ratio. Therefore, circulating C10:0 was associated with several genera bacteria such as Prevotella (positive) and Anaerotruncus (negative). Two classes of Firmicutes, Bacilli and Erysipelotrichi, were positively correlated with PL- C20:3 n-6 and CE- 18:1 n-9, respectively. TM7 and Bacteroidetes were inversely correlated with PL-SFAs and CE- 18:2 n-6, respectively.

Disrupted Lipid Homeostasis and Loss of IRF4 Impairs B-Cell and Plasma Cell Development in a Murine Model of Accelerated Aging

The aging immune system is characterized by increased bone marrow (BM) adiposity, myeloid skewing, impaired lymphocyte maturation, and loss of hematopoietic stem and progenitor cell (HSPC) regenerative capacity. Human systemic aging studies have found alterations in lipid and fatty acid metabolism, such as increased saturated fatty acid accumulation and decays in n-3 polyunsaturated fatty acid (PUFA) species leading to cellular membrane rigidity. However, the extent to which impaired fatty acid metabolism contributes to immune system aging and HSPC development is largely unexplored. In this study, we performed multi-omics studies to characterize BM aging phenotypes in a recently described mouse model that exhibits signs of accelerating aging in brain and eye tissues. This robust aging model expresses a mutant inactive form of the very long chain (VLC) PUFA elongation enzyme, Elongation of very long chain fatty acids protein 2 (ELOVL2), which is responsible for the elongation of 22-carbon PUFAs to 24-carbon PUFAs. These VLC-PUFAs are synthesized in vivo and are not readily available through dietary means. Previous studies using this mouse model demonstrated that Elovl2 DNA methylation-dependent and mutation-associated loss of function is a key driver of age-related defects in eye and brain tissues, however the hematopoietic system has not been characterized to date in this model. To investigate the extent to which impaired VLC-PUFA production in the setting of ELOVL2 enzymatic deficiency might also accelerate blood stem cell aging phenotypes, multi-omics studies were performed in murine BM samples from young (3 months old) and aged (18 months old) wild-type mice, compared with age-matched Elovl2 mutant mice. Total BM samples were subjected to lipidomics analyses, whole transcriptome RNA-sequencing (RNA-seq), and ATAC-seq analyses. Lipidomic profiling showed an almost complete depletion of direct and secondary products of ELOVL2 in BM isolated from mutant animals, suggesting significant changes in the biophysical properties of membranes in the cells. Gene set enrichment analyses (Reactome) of RNA-seq data revealed that pathways involving B cell receptor (BCR) signalling and immunoregulatory interactions between lymphoid and non-lymphoid cells were among the most differentially regulated in Elovl2 mutant mouse BM compared to age-matched controls. Key lymphoid lineage maturation markers (Cd19, Cd22, and Slamf7, among others) were downregulated in the BM of aged wild-type mice, and to a greater extent in Elovl2 mutant animals. This was accompanied by a significant downregulation of the lymphoid and plasma cell transcription factor, interferon-regulatory factor-4 (Irf4), in aged and Elovl2 mutant groups compared with young mice. In addition, phenotypic analyses of B cell lineage marker protein expression were performed by flow cytometry to confirm depletion of lymphoid cell populations and Irf4 expression in this model. Finally, ATAC-seq data revealed changes in DNA accessibility related to Elovl2 mutation, suggesting significant epigenetic changes in nuclear programs. These findings suggest that Elovl2 loss of function in a murine model of accelerated aging promotes diverse lipidomic, transcriptomic and chromatin alterations targeting lymphoid populations in murine BM, which may be mechanistically driven by a downregulation of Irf4. Together, these results provide insights into a functional link between disrupted lipid homeostasis and aging-related defects in lymphocyte maturation typified by loss of B-cell and plasma cell populations. Together, modulation of lipid catabolism pathways may provide a novel avenue for reversing a variety of age-related immune deficits including enhanced susceptibility to infection.

Signatures of Mitochondrial Dysfunction and Impaired Fatty Acid Metabolism in Plasma of Patients with Post-Acute Sequelae of COVID-19 (PASC).

Exercise intolerance is a major manifestation of post-acute sequelae of severe acute respiratory syndrome coronavirus infection (PASC, or "long-COVID"). Exercise intolerance in PASC is associated with higher arterial blood lactate accumulation and lower fatty acid oxidation rates during graded exercise tests to volitional exertion, suggesting altered metabolism and mitochondrial dysfunction. It remains unclear whether the profound disturbances in metabolism that have been identified in plasma from patients suffering from acute coronavirus disease 2019 (COVID-19) are also present in PASC. To bridge this gap, individuals with a history of previous acute COVID-19 infection that did not require hospitalization were enrolled at National Jewish Health (Denver, CO, USA) and were grouped into those that developed PASC (n = 29) and those that fully recovered (n = 16). Plasma samples from the two groups were analyzed via mass spectrometry-based untargeted metabolomics and compared against plasma metabolic profiles of healthy control individuals (n = 30). Observational demographic and clinical data were retrospectively abstracted from the medical record. Compared to plasma of healthy controls or individuals who recovered from COVID-19, PASC plasma exhibited significantly higher free- and carnitine-conjugated mono-, poly-, and highly unsaturated fatty acids, accompanied by markedly lower levels of mono-, di- and tricarboxylates (pyruvate, lactate, citrate, succinate, and malate), polyamines (spermine) and taurine. Plasma from individuals who fully recovered from COVID-19 exhibited an intermediary metabolic phenotype, with milder disturbances in fatty acid metabolism and higher levels of spermine and taurine. Of note, depletion of tryptophan-a hallmark of disease severity in COVID-19-is not normalized in PASC patients, despite normalization of kynurenine levels-a tryptophan metabolite that predicts mortality in hospitalized COVID-19 patients. In conclusion, PASC plasma metabolites are indicative of altered fatty acid metabolism and dysfunctional mitochondria-dependent lipid catabolism. These metabolic profiles obtained at rest are consistent with previously reported mitochondrial dysfunction during exercise, and may pave the way for therapeutic intervention focused on restoring mitochondrial fat-burning capacity.

Impaired fatty acid metabolism perpetuates lipotoxicity along the transition to chronic kidney injury.

Energy metabolism failure in proximal tubule cells (PTCs) is a hallmark of chronic kidney injury. We combined transcriptomic, metabolomic, and lipidomic approaches in experimental models and patient cohorts to investigate the molecular basis of the progression to chronic kidney allograft injury initiated by ischemia/reperfusion injury (IRI). The urinary metabolome of kidney transplant recipients with chronic allograft injury and who experienced severe IRI was substantially enriched with long chain fatty acids (FAs). We identified a renal FA-related gene signature with low levels of carnitine palmitoyltransferase 2 (Cpt2) and acyl-CoA synthetase medium chain family member 5 (Acsm5) and high levels of acyl-CoA synthetase long chain family member 4 and 5 (Acsl4 and Acsl5) associated with IRI, transition to chronic injury, and established chronic kidney disease in mouse models and kidney transplant recipients. The findings were consistent with the presence of Cpt2-Acsl4+Acsl5+Acsm5- PTCs failing to recover from IRI as identified by single-nucleus RNA-Seq. In vitro experiments indicated that ER stress contributed to CPT2 repression, which, in turn, promoted lipids' accumulation, drove profibrogenic epithelial phenotypic changes, and activated the unfolded protein response. ER stress through CPT2 inhibition and lipid accumulation engaged an auto-amplification loop leading to lipotoxicity and self-sustained cellular stress. Thus, IRI imprints a persistent FA metabolism disturbance in the proximal tubule, sustaining the progression to chronic kidney allograft injury.

Association of placental fatty acid desaturase 2 (FADS2) methylation with maternal fatty acid levels in women with preeclampsia

IntroductionBiosynthesis of long-chain polyunsaturated fatty acids requires sequential activities of desaturases and elongases for conversion of fatty acid precursors to products. The delta-6 desaturase enzyme, encoded by FADS2 gene, is a rate limiting enzyme in this pathway. Alterations in D6D enzyme activity can lead to altered fatty acid profiles. ObjectivesTo examine differences in placental DNA methylation (DNAm) and expression of FADS2 gene in preeclampsia women compared to normal women and their association with maternal variables (plasma fatty acids, desaturase enzyme index, blood pressure), placental weight and birth outcomes. MethodsDNAm and expression of FADS2 gene were examined in placentae of normotensive (n = 100) control and preeclampsia (n = 100) women using pyrosequencing and quantitative real-time PCR respectively. Women with preeclampsia included those delivering at term (n = 43, gestation ≥ 37 weeks; T-PE) or preterm (n = 57, gestation < 37 weeks; PT-PE). A total of 26 CpGs in FADS2 promoter and region around it, were analysed in two PCR reactions (region 1 and 2). ResultsOut of 13 CpGs in region 1, significant hypermethylation was noted at CpG3 in T-PE (p = 0.03) and of 13 CpGs in region 2, CpG2 (p = 0.008), CpG11 (p = 0.04), CpG12 (p = 0.001) were hypomethylated and CpG13 (p = 0.001) was hypermethylated in preeclampsia group, as compared to controls. FADS2 expression was lower in PT-PE as compared to controls (p = 0.04). DNAm at various CpGs in the FADS2 were associated with maternal plasma FADS2 enzyme index and also associated with maternal fatty acid levels. However, we did not observe any association of DNAm with maternal blood pressure, placental weight and birth outcomes. ConclusionsThis study for the first time reports differential methylation of FADS2 and its association with impaired maternal fatty acid metabolism in preeclampsia and provides a mechanistic basis to our earlier observations of altered maternal LCPUFA levels in women with preeclampsia.

Targeted Metabolomics Reveals Plasma Biomarkers and Metabolic Alterations of the Aging Process in Healthy Young and Older Adults

With the exponential rise in the older population for the coming years, many studies have aimed to further investigate potential solutions to the aging process. It has been well understood that age is the largest risk factor for chronic disease due to younger individuals possessing more prevalent and adaptive metabolic networks that result in overall health and homeostasis. During the lifecycle, several physiological alterations ensue throughout the metabolic system that attribute to functional decline. In this cross‐sectional analysis, a targeted metabolomic approach was applied to investigate the plasma metabolome of 151 young (n = 75) and older adults (n = 76). A corrected MANOVA model was generated, with such covariates as gender, BMI, and chronic condition score (CCS), to analyze the aging process of the two populations. Metabolites associated with impaired fatty acid metabolism were found to be most significant: palmitic acid (p &lt; 0.001), 3‐hexenedioic acid (p &lt; 0.001), stearic acid (p = 0.005), and decanoylcarnitine (p = 0.036). Derivatives of amino acid metabolism, 1‐methlyhistidine (p = 0.035) and methylhistamine (p = 0.027), were found to be increased in the younger population and several novel metabolites were identified, such as cadaverine (p = 0.034), 4‐ethylbenzoic acid (p = 0.029), and 3‐hexenedioic acid (p &lt; 0.001). Principal component analysis was conducted and highlighted a shift in the metabolome for both groups. Pathway and enrichment analyses uncovered several impacted pathways that elucidate the metabolic alterations in the older population and aid in further explanation of the aging process. As a result, we offer a better understanding of the aging metabolome and potentially reveal new biomarkers for future study.

A Floppy Infant with Facial Dysmorphism.

A Floppy Infant with Facial Dysmorphism.

Intrauterine growth restriction elevates circulating acylcarnitines and suppresses fatty acid metabolism genes in the fetal sheep heart.

At birth, the mammalian myocardium switches from using carbohydrates as the primary energy substrate to free fatty acids as the primary fuel. Thus, a compromised switch could jeopardize normal heart function in the neonate. Placental embolization in sheep is a reliable model of intrauterine growth restriction (IUGR). It leads to suppression of both proliferation and terminal differentiation of cardiomyocytes. We hypothesized that the expression of genes regulating cardiac fatty acid metabolism would be similarly suppressed in IUGR, leading to compromised processing of lipids. Following 10 days of umbilicoplacental embolization in fetal sheep, IUGR fetuses had elevated circulating long-chain fatty acylcarnitines compared with controls (C14: CTRL 0.012 ± 0.005nmol/ml vs. IUGR 0.018 ± 0.005nmol/ml, P < 0.05; C18: CTRL 0.027 ± 0.009nmol/mol vs. IUGR 0.043 ± 0.024nmol/mol, P < 0.05, n = 12 control, n = 12 IUGR) indicative of impaired fatty acid metabolism. Uptake studies using fluorescently tagged BODIPY-C12-saturated free fatty acid in live, isolated cardiomyocytes showed lipid droplet area and number were not different between control and IUGR cells. mRNA levels of sarcolemmal fatty acid transporters (CD36, FATP6), acylation enzymes (ACSL1, ACSL3), mitochondrial transporter (CPT1), β-oxidation enzymes (LCAD, HADH, ACAT1), tricarboxylic acid cycle enzyme (IDH), esterification enzymes (PAP, DGAT) and regulator of the lipid droplet formation (BSCL2) gene were all suppressed in IUGR myocardium (P < 0.05). However, protein levels for these regulatory genes were not different between groups. This discordance between mRNA and protein levels in the stressed myocardium suggests an adaptive protection of key myocardial enzymes under conditions of placental insufficiency. KEY POINTS: The fetal heart relies on carbohydrates in utero and must be prepared to metabolize fatty acids after birth but the effects of compromised fetal growth on the maturation of this metabolic system are unknown. Plasma fatty acylcarnitines are elevated in intrauterine growth-restricted (IUGR) fetuses compared with control fetuses, indicative of impaired fatty acid metabolism in fetal organs. Fatty acid uptake and storage are not different in IUGR cardiomyocytes compared with controls. mRNA levels of genes regulating fatty acid transporter and metabolic enzymes are suppressed in the IUGR myocardium compared with controls, while protein levels remain unchanged. Mismatches in gene and protein expression, and increased circulating fatty acylcarnitines may have long-term implications for offspring heart metabolism and adult health in IUGR individuals. This requires further investigation.

Serial change in perfusion\u2013metabolism mismatch after coronary artery bypass grafting

ObjectiveMyocardial ischemia is known to suppress fatty acid metabolism and favor glucose metabolism. However, changes in myocardial metabolism after coronary revascularization are not fully elucidated.MethodsThirty-eight patients with coronary artery disease were retrospectively enrolled. These patients had undergone stress perfusion single photon emission computed tomography (SPECT) and 123I-BMIPP SPECT in both the short-term (6.4 ± 4.7 months) and mid-term (29.9 ± 7.2 months) after isolated coronary artery bypass grafting. Tracer uptake was graded using a 17-segment, 5-point scoring model. Serial changes in SRS (summed rest score), SDS (summed difference score), the BMIPP score (total defect score of BMIPP), and the mismatch score (BMIPP score–SRS) were evaluated. In addition, persistent perfusion–metabolism mismatch (PM) was defined as mismatch score minus SDS of 3 or more during the mid-term postoperative period. The clinical parameters associated with PM were examined.ResultsFrom short- to mid-term postoperative period, the extent of infarcted myocardium (SRS) did not change significantly (7.8 ± 8.0 to 7.1 ± 7.0, P = 0.117). The extent of ischemic myocardium (SDS), the BMIPP score and the mismatch score, which reflects perfusion–metabolism mismatch, were significantly improved (2.0 ± 2.8 to 0.7 ± 1.0, P = 0.010; 12.2 ± 9.0 to 9.5 ± 7.9, P < 0.001; 4.4 ± 3.7 to 2.5 ± 2.6, P < 0.001; respectively). Remarkably, perfusion–metabolism mismatch persisted in 13 patients (34%) even in the mid-term postoperative period. eGFR and SYNTAX score were independent predictors of persistent perfusion–metabolic mismatch in multivariable analysis (OR = 0.951, 95% CI 0.898–0.985, P = 0.010 and OR = 1.126, 95% CI 1.011–1.254, P = 0.031, respectively). The mismatch score both in the short- and mid-term significantly correlated with SYNTAX score (r = 0.400 and r = 0.472, respectively).ConclusionsFatty acid metabolism disturbance improved from short- to mid-term postoperative period in patients with successful reperfusion by coronary artery bypass grafting. However, in patients with severe atherosclerosis, impaired fatty acid metabolism was sustained until the mid-term postoperative period, even though ischemia had resolved.