Phosphatidylcholine Metabolism Research Articles

Mutation of Serine 32 to Threonine in Peroxiredoxin 6 Preserves Its Structure and Enzymatic Function but Abolishes Its Trafficking to Lamellar Bodies

Peroxiredoxin 6 (Prdx6), a bifunctional protein with phospholipase A2 (aiPLA2) and GSH peroxidase activities, protects lungs from oxidative stress and participates in lung surfactant phospholipid turnover. Prdx6 has been localized to both cytosol and lamellar bodies (LB) in lung epithelium, and its organellar targeting sequence has been identified. We propose that Prdx6 LB targeting facilitates its role in the metabolism of lung surfactant phosphatidylcholine (PC). Ser-32 has been identified as the active site in Prdx6 for aiPLA2 activity, and this activity was abolished by the mutation of serine 32 to alanine (S32A). However, aiPLA2 activity was unaffected by mutation of serine 32 in Prdx6 to threonine (S32T). Prdx6 protein expression and aiPLA2 activity were normal in the whole lung of a "knock-in" mouse model carrying an S32T mutation in the Prdx6 gene but were absent from isolated LB. Analyses by proximity ligation assay in lung sections demonstrated the inability of S32T Prdx6 to bind to the chaperone protein, 14-3-3ϵ, that is required for LB targeting. The content of total phospholipid, PC, and disaturated PC in lung tissue homogenate, bronchoalveolar lavage fluid, and lung LB was increased significantly in Prdx6-S32T mutant lungs, whereas degradation of internalized [(3)H]dipalmitoyl-PC was significantly decreased. Thus, Thr can substitute for Ser for the enzymatic activities of Prdx6 but not for its targeting to LB. These results confirm an important role for LB Prdx6 in the degradation and remodeling of lung surfactant phosphatidylcholine.

Choline and its metabolites are differentially associated with cardiometabolic risk and cardio‐ and cerebro‐vascular disease

Considerable attention has recently been given to the potential role of choline in cardiovascular disease. While the main focus has been on the microbial metabolism of phosphatidylcholine and the production of a pro‐atherosclerotic metabolite trimethylamine‐N‐oxide, there are also a number of links between choline and cardiometabolic risk through its role in lipid and one‐carbon metabolism. Phosphatidylcholine, a metabolite of choline, is an essential component of lipoproteins, and its biosynthesis in the liver is critical for the synthesis and secretion of very‐low density lipoproteins. Choline is also a precursor of betaine, which is a methyl donor for the conversion of homocysteine (Hcy) to methionine. Some data suggest differing associations of plasma choline and betaine with components of the metabolic syndrome, with an unfavorable cardiovascular risk profile associated with higher choline and a more favorable one with higher betaine plasma concentrations. Whether this same relationship holds true for cerebrovascular disease has not yet been evaluated. In this study, we've evaluated the associations of plasma choline and choline‐related compounds with cardiometabolic risk factors, history of cardiovascular disease, and cerebrovascular pathology in a cross‐sectional analysis of 293 men and women (mean age = 75 years, sd = 8.6) from the Nutrition, Aging, and Memory in Elders (NAME) cohort who had undergone magnetic resonance imaging of the brain and anthropometric and blood pressure measurement, had archived fasting plasma, and who had been administered a health history questionnaire. Plasma concentrations of choline, phophatidylcholine, and betaine were measured using liquid chromatography‐stable isotope dilution‐multiple reaction monitoring –mass spectrometry. Multiple linear and logistic regression models were used to examine relationships of plasma measures with cardiometabolic risk factors, history of cardiovascular disease, and radiological evidence of cerebral large vessel and small vessel infarcts. We found that plasma concentrations of phosphatidylcholine were positively related to low‐density lipoprotein cholesterol (LDL), high density lipoprotein cholesterol (HDL), and triglycerides (TG) (p<0.0001 for all), while the ratio of plasma betaine to choline concentrations were positively related to HDL (p=0.02) and negatively related to TG and Hcy (p<0.0001 for both). Higher concentrations of both metabolites were associated with lower risk of hypertension (3rd vs 1st tertile, OR=0.42, 95% CI 0.18 – 0.99 for both). Participants in the third tertile of plasma choline concentrations had higher odds of having a history of cardiovascular disease (OR =3.26, 95% CI 1.67 – 6.36) and cerebral large vessel infarct (OR=4.19, 95% CI 1.2 – 13.58), but lower odds of cerebral small vessel infarct (OR=0.48, 95% CI 0.23 – 0.98). Our findings that choline and its metabolites had differential associations with cardiometabolic risk factors and subtypes of vascular disease suggest differing roles in the pathogenesis of cardiovascular and cerebral large vessel disease versus small vessel disease.Support or Funding InformationUSDA agreement No. 58‐1950‐0‐014; NIA AG21790‐01; NHLBIT32‐HL069772

Metformin Decouples Phospholipid Metabolism in Breast Cancer Cells.

IntroductionThe antidiabetic drug metformin, currently undergoing trials for cancer treatment, modulates lipid and glucose metabolism both crucial in phospholipid synthesis. Here the effect of treatment of breast tumour cells with metformin on phosphatidylcholine (PtdCho) metabolism which plays a key role in membrane synthesis and intracellular signalling has been examined.MethodsMDA-MB-468, BT474 and SKBr3 breast cancer cell lines were treated with metformin and [3H-methyl]choline and [14C(U)]glucose incorporation and lipid accumulation determined in the presence and absence of lipase inhibitors. Activities of choline kinase (CK), CTP:phosphocholine cytidylyl transferase (CCT) and PtdCho-phospholipase C (PLC) were also measured. [3H] Radiolabelled metabolites were determined using thin layer chromatography.ResultsMetformin-treated cells exhibited decreased formation of [3H]phosphocholine but increased accumulation of [3H]choline by PtdCho. CK and PLC activities were decreased and CCT activity increased by metformin-treatment. [14C] incorporation into fatty acids was decreased and into glycerol was increased in breast cancer cells treated with metformin incubated with [14C(U)]glucose.ConclusionThis is the first study to show that treatment of breast cancer cells with metformin induces profound changes in phospholipid metabolism.

Phosphatidylcholine kinetics in neonatal rat lungs and the effects of rhuKGF and betamethasone.

Surfactant, synthesized by type II pneumocytes (PN-II), mainly comprises phosphatidylcholine (PC) and is essential to prevent neonatal respiratory distress. Furthermore, PC is essential to lung tissue growth and maintenance as a membrane component. Recent findings suggest that the lung contributes to systemic lipid homeostasis via PC export through ABC-A1 transporter expression. Hence it is important to consider pharmacological interventions in neonatal lung PC metabolism with respect to such export. Five-day-old rats were treated with carrier (control), intraperitoneal betamethasone, subcutaneous recombinant human keratinocyte growth factor (rhuKGF), or their combination for 48 h. Animals were intraperitoneally injected with 50 mg/kg [D9-methyl]choline chloride 1.5, 3.0, and 6.0 h before death at day 7, and lung lavage fluid (LLF) and tissue were harvested. Endogenous PC, D9-labeled PC species, and their water-soluble precursors (D9-)choline and (D9-)phosphocholine were determined by tandem mass spectrometry. Treatment increased secreted and tissue PC pools but did not change equilibrium composition of PC species in LLF. However, all treatments increased specific surfactant components in tissue. In control rats, peak D9-PC in lavaged lung was reached after 3 h and was decreased at 6 h. Only 13% of this net loss in lavaged lung was found in LLF. Such decrease was not present in lungs treated with betamethasone and/or with rhuKGF. D9-PC loss at 3-6 h and PC synthesis calculated from D9 enrichment of phosphocholine indicated that daily synthesis rate is higher than total pool size. We conclude that lung tissue contributes to systemic PC homeostasis in neonatal rats, which is altered by glucocorticoid and rhuKGF treatment.

Higher plasma levels of lysophosphatidylcholine 18:0 are related to a lower risk of common cancers in a prospective metabolomics study.

BackgroundFirst metabolomics studies have indicated that metabolic fingerprints from accessible tissues might be useful to better understand the etiological links between metabolism and cancer. However, there is still a lack of prospective metabolomics studies on pre-diagnostic metabolic alterations and cancer risk.MethodsAssociations between pre-diagnostic levels of 120 circulating metabolites (acylcarnitines, amino acids, biogenic amines, phosphatidylcholines, sphingolipids, and hexoses) and the risks of breast, prostate, and colorectal cancer were evaluated by Cox regression analyses using data of a prospective case-cohort study including 835 incident cancer cases.ResultsThe median follow-up duration was 8.3 years among non-cases and 6.5 years among incident cases of cancer. Higher levels of lysophosphatidylcholines (lysoPCs), and especially lysoPC a C18:0, were consistently related to lower risks of breast, prostate, and colorectal cancer, independent of background factors. In contrast, higher levels of phosphatidylcholine PC ae C30:0 were associated with increased cancer risk. There was no heterogeneity in the observed associations by lag time between blood draw and cancer diagnosis.ConclusionChanges in blood lipid composition precede the diagnosis of common malignancies by several years. Considering the consistency of the present results across three cancer types the observed alterations point to a global metabolic shift in phosphatidylcholine metabolism that may drive tumorigenesis.Electronic supplementary materialThe online version of this article (doi:10.1186/s12916-016-0552-3) contains supplementary material, which is available to authorized users.

Metabolomic analysis of human synovial fluid and plasma reveals that phosphatidylcholine metabolism is associated with both osteoarthritis and diabetes mellitus

This study was to investigate how OA patients with metabolic syndrome (MetS) are different metabolically from OA patients without MetS components and healthy individuals. A two-stage case–control study design was utilized. Synovial fluid (SF) and plasma samples were collected from patients undergoing total knee joint replacement due to primary OA and healthy controls (only plasma) and metabolically profiled using UPLC-MS coupled with assay kit which measures 186 metabolites. Orthogonal projection to latent structure-discriminant analysis and linear regression were used to identify metabolic markers for discriminating OA patients with MetS components from those without and healthy individuals. 54 paired SF and plasma samples from knee OA patients and 30 plasma samples from healthy controls were included in the discovery stage, and 143 plasma samples (72 from knee OA patients and 71 from the age, sex, and BMI matched controls) were included in the validation stage. OA patients with MetS can be clearly discriminated from OA patients without MetS based on the metabolite profiles of both SF and plasma and the separation appeared to be driven by type 2 diabetes but not obesity, hypertension, or dyslipidemia. When compared with OA patients with diabetes, OA without diabetes, and healthy controls, phosphatidylcholine acyl-alkyl C34:3 (PC ae C34:3) and phosphatidylcholine acyl-alkyl C36:3 (PC ae C36:3) were identified and confirmed to be associated with the concurrence of OA and diabetes (all p < 0.003). The study demonstrated that altered phosphatidylcholine metabolism was associated with both OA and diabetes mellitus.

Metabolic disturbances in plasma as biomarkers for Huntington's disease

Huntington's disease (HD), caused by expanded CAG repeats encoding a polyglutamine tract in the huntingtin protein, presents with a predominant degeneration of neurons in the striatum and cortex. Although a few studies have identified substantial metabolite alterations in plasma, the picture of plasma metabolomics of HD has not been clearly depicted yet. Using a global metabolomics screening for plasma from 15 HD patients and 17 controls, HD patient group was separated from the control group by a panel of metabolites belonging to carnitine, amino acid and phosphatidylcholine species. The quantification of 184 related metabolites (including carnitine, amino acid and phosphatidylcholine species) in 29 HD patients, 9 presymptomatic HD carriers and 44 controls further showed one up-regulated (glycine) and 9 down-regulated metabolites (taurine, serotonin, valine, isoleucine, phosphatidylcholine acyl-alkyl C36:0 and C34:0 and lysophosphatidylcholine acyl C20:3). To understand the biosynthetic alterations of phosphatidylcholine in HD, we examined the expression levels and activities of a panel of key enzymes responsible for phosphatidylcholine metabolism. The results showed down-regulation of PCYT1A and increased activity of phospholipase A2 in HD leukocytes. These metabolic profiles strongly indicate that disturbed metabolism is involved in pathogenesis of HD and provide clue for the development of novel treatment strategies for HD.

Knockout of arsenic (+3 oxidation state) methyltransferase results in sex-dependent changes in phosphatidylcholine metabolism in mice

Knockout of arsenic (+3 oxidation state) methyltransferase results in sex-dependent changes in phosphatidylcholine metabolism in mice

Distinct urinary lipid profile in children with focal segmental glomerulosclerosis.

Focal segmental glomerulosclerosis (FSGS) accounts for the majority of new-onset end-stage renal disease (ESRD) during adolescence. FSGS treatment is a great challenge for pediatric nephrologists due to intertwined molecular pathways underlining its complex pathophysiology. There is emerging evidence showing that perturbed lipid metabolism plays a role in the pathophysiology of FSGS. We postulate that the nephrotic milieu in FSGS differs from minimal change disease (MCD) and that urinary lipidomics can be used as a tool for early diagnosis of FSGS. We explored the urinary lipid profile of patients with FSGS and MCD using an unbiased metabolomics approach. We discovered a unique lipid signature characterized by increased concentration of fatty acid (FA) and lysophosphatidylcholines (LPC) and a decrease in urinary concentration of phosphatidylcholine (PC) in patients with FSGS. These findings indicate increased metabolism of membrane phospholipid PC by phospholipase A2 (PLA2), resulting in higher urinary concentrations of LPC and FA. We propose that increased PC by-products can be used as a biomarker to diagnose FSGS and shed light on the mechanism of tubular and podocyte damage. Validation of identified urinary lipids as a biomarker in predicting the diagnosis and progression of FSGS in a larger patient population is warranted.

Blood metabolite markers of cognitive performance and brain function in aging

We recently showed that Alzheimer's disease patients have lower plasma concentrations of the phosphatidylcholines (PC16:0/20:5; PC16:0/22:6; and PC18:0/22:6) relative to healthy controls. We now extend these findings by examining associations between plasma concentrations of these PCs with cognition and brain function (measured by regional resting state cerebral blood flow; rCBF) in non-demented older individuals. Within the Baltimore Longitudinal Study of Aging neuroimaging substudy, participants underwent cognitive assessments and brain 15O-water positron emission tomography. Plasma phosphatidylcholines concentrations (PC16:0/20:5, PC16:0/22:6, and PC18:0/22:6), cognition (California Verbal Learning Test (CVLT), Trail Making Test A&B, the Mini-Mental State Examination, Benton Visual Retention, Card Rotation, and Fluencies—Category and Letter), and rCBF were assessed. Lower plasma phosphatidylcholine concentrations were associated with lower baseline memory performance (CVLT long delay recall task—PC16:0/20:5: −2.17–1.39−0.60 p = 0.001 (β with 95% confidence interval subscripts)) and lower rCBF in several brain regions including those associated with memory performance and higher order cognitive processes. Our findings suggest that lower plasma concentrations of PC16:0/20:5, PC16:0/22:6, and PC18:0/22:6 are associated with poorer memory performance as well as widespread decreases in brain function during aging. Dysregulation of peripheral phosphatidylcholine metabolism may therefore be a common feature of both Alzheimer's disease and age-associated differences in cognition.

Listening to Our Gut: Contribution of Gut Microbiota and Cardiovascular Risk in Diabetes Pathogenesis

What we understand about diabetes from decades of genetics research is now being supplemented with exciting new evidence based on a better understanding of how one of the biggest "environmental" factors the body is exposed to is influencing the pathogenesis of disease. The recent discovery that certain dietary nutrients possessing a trimethylamine (TMA) moiety (namely choline/phosphatidylcholine and L-carnitine) participate in the development of atherosclerotic heart disease has renewed attention towards the contributions of gut microbiota in the development of cardiovascular diseases. Collectively, animal and human studies reveal that conversion of these nutrient precursors to trimethylamine N-oxide (TMAO) depends on both microbial composition and host factors, and can be induced by dietary exposures. In addition, circulating TMAO levels are strongly linked to cardiovascular disease risks and various adverse cardio-renal consequences. Our group and others have further demonstrated that circulating TMAO levels are elevated in patients with type 2 diabetes mellitus compared to healthy controls and gut microbiota-dependent phosphatidylcholine metabolism has been implicated in metabolic dysregulation and insulin resistance in animal models. Therefore, preventive strategies to minimize adverse consequences associated with TMAO generation in the diabetic population are warranted.

Abstract 364: Pathological Effects of Trimethylamine N-oxide (TMAO) on Pressure Overload-induced Heart Failure

Rationale: Trimethylamine N-oxide (TMAO), a metabolite formed in the metabolism of dietary phosphatidylcholine, is elevated in the circulation of patients at increased risk for heart attack and adverse prognosis during heart failure. Objective: We investigated the effects of dietary choline and TMAO on the severity of heart failure following transverse aortic constriction (TAC). Methods and Results: Male C57Blk/6J mice were fed either control diet, a diet containing choline (1.2%) or a diet containing TMAO (0.12%) at 3 weeks prior to surgical TAC and were studied for 12 weeks. Left ventricular (LV) structure and function were monitored at 3 week intervals and myocardial tissue was collected at 12 weeks. Plasma TMAO levels were significantly (p &lt; 0.01) increased in the choline (28.64 ± 2.30 μM) and TMAO (28.18 ± 4.27 μM) compared to the control group (1.87 ± 0.26 μM). Left ventricular ejection fraction (LVEF) was significantly (p &lt; 0.05) worse in mice fed TMAO compared to control diet. LV end-diastolic and end-systolic diameters were significantly (p &lt; 0.05) increased in the TMAO group compared to control diet. Myocardial fibrosis as measured with Picrosirius Red staining was also significantly greater (p &lt; 0.01) in the TMAO and choline groups. Circulating BNP levels were significantly (p &lt; 0.05) increased in the TMAO and choline groups. Conclusions: These data demonstrate that heart failure severity is significantly enhanced in mice fed diets containing either TMAO or choline. Our results suggest that consumption of food high in dietary nutrients that increase TMAO levels such as phosphatidylcholine may increase heart failure severity.

Effect of Lactobacillus casei Shirota supplementation on trimethylamine-N-oxide levels in patients with metabolic syndrome: An open-label, randomized study.

Recent studies in animal models have shown a link between ingestion of dietary phosphatidylcholine (PC), choline, l-carnitine and cardiovascular risk. Intestinal microbiota-dependent metabolism of PC and l-carnitine is involved in formation of trimethylamine (TMA), which is further metabolized to the proatherogenic compound trimethylamine-N-oxide (TMAO). It has been suggested that changes in gut microbiota by supplementation of probiotic drinks might alter TMAO levels. Hence, the aim of this analysis was to investigate the impact of Lactobacillus casei Shirota (LcS) on formation of TMAO in subjects with metabolic syndrome. In a single-center, prospective, randomized-controlled study 30 subjects with metabolic syndrome were randomized to receive either 3 times daily 6.5 × 10(9) CFU (colony-forming units) LcS (probiotic group) or not (standard therapy group) for 12 weeks. TMAO plasma levels were quantified by means of liquid chromatography and tandem mass spectrometry. Thirteen patients in the probiotic group and 15 in the standard therapy group finished the study. Mean age was 52 ± 11 and 55 ± 9 years, respectively. TMAO levels decreased during the intervention period in both groups (from 4.66 ± 2.66 μM to 4.31 ± 2.04 μM in the probiotic group and from 4.64 ± 2.75 μM to 4.40 ± 2.14 μM in the control group). Changes in TMAO between subjects receiving LcS (-0.25 ± 2.39 μM) and controls (-0.34 ± 2.23 μM) were not significantly different (p = 0.510). In conclusion, intake of LcS for 12 weeks did not affect levels of TMAO in patients with metabolic syndrome.

LC–MS-based serum metabolomic analysis reveals dysregulation of phosphatidylcholines in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive cancers with poor prognosis. Here, we carried out liquid chromatography–quadrupole time-of-flight mass spectrometry (LC–Q–TOF-MS)-based untargeted metabolomic analysis of ESCC serum samples. Statistical analysis resulted in the identification of 652 significantly dysregulated molecular features in serum from ESCC patients as compared to the healthy subjects. Phosphatidylcholines were identified as a major class of dysregulated metabolites in this study suggesting potential perturbation of phosphocholine metabolism in ESCC. By using a targeted MS/MS approach both in positive and negative mode, we were able to characterize and confirm the structure of seven metabolites. Our study describes a quantitative LC–MS approach for characterizing dysregulated lipid metabolism in ESCC. Biological significanceAltered metabolism is a hallmark of cancer. We carried out (LC–MS)-based untargeted metabolomic profiling of serum from esophageal squamous cell carcinoma (ESCC) patients to characterize dysregulated metabolites. Phosphatidylcholine metabolism was found to be significantly altered in ESCC. Our study illustrates the use of mass spectrometry-based metabolomic analysis to characterize molecular alterations associated with ESCC. This article is part of a Special Issue entitled: Proteomics in India.

Reductions of docosahexaenoic acid-containing phosphatidylcholine levels in the anterior horn of an ALS mouse model

In this study, we analyzed the spatiotemporal alterations of phospholipid composition in the spinal cord of an amyotrophic lateral sclerosis (ALS) mouse model (G93A-mutated human superoxide dismutase 1 transgenic mice [SOD1G93A mice]) using imaging mass spectrometry (IMS), a powerful method to visualize spatial distributions of various types of molecules in situ. Using this technique, we deciphered the phospholipid distribution in the pre-symptomatic stage, early stage after disease onset, and terminal stages of disease in female SOD1G93A mouse spinal cords. These experiments revealed a significant decrease in levels of docosahexaenoic acid (DHA)-containing phosphatidylcholines (PCs), such as PC (diacyl-16:0/22:6), PC (diacyl-18:0/22:6), and PC (diacyl-18:1/22:6) in the L5 anterior horns of terminal stage (22-week-old) SOD1G93A mice. The reduction in PC (diacyl-16:0/22:6) level could be reflecting the loss of motor neurons themselves in the anterior horn of the spinal cord in ALS model mice. In contrast, other PCs, such as PC (diacyl-16:0/16:0), were observed specifically in the L5 dorsal horn gray matter, and their levels did not vary between ALS model mice and controls. Thus, our study showed a significant decrease in DHA-containing PCs, but not other PCs, in the terminal stage of ALS in model mice, which is likely to be a reflection of neuronal loss in the anterior horns of the spinal cords. Given its enrichment in dorsal sensory regions, the preservation of PC (diacyl-16:0/16:0) may be the result of spinal sensory neurons being unaffected in ALS. Taken together, these findings suggest that ALS spinal cords show significant alterations in PC metabolism only at the terminal stage of the disease, and that these changes are confined to specific anatomical regions and cell types.

Targeting Plasmodium falciparum Phosphethanolamine Methyltransferase for Malaria Therapy

Plasmodium falciparum, the causative agent of the deadliest form of malaria, multiplies asexually within human erythrocytes to produce up to 36 new daughter parasites per red blood cell, and undergoes gametocytogenesis to produce sexual forms, which are essential for successful malaria transmission. Available data suggest an essential role of phosphatidylcholine (PC) metabolism in these processes. PC synthesis is fueled by precursors such as choline, serine, ethanolamine and fatty acids scavenged from the host. Metabolic analyses suggest the presence of two pathways for the synthesis of PC in P. falciparum: the CDP-choline pathway from choline and the transmethylation (PMT) pathway from serine. Genetic and pharmacological studies demonstrated that the two pathways play distinct and essential functions in parasite development, survival and sexual differentiation. The limiting step in the PMT pathway is catalyzed by the phosphoethanolamine methyltransferase PfPMT. The PMT enzyme reaction does not occur in human cells, and no homologs of PfPMT are present in mammals, making it an ideal target for development of specific, selective and safe antimalarials. Equally important PMT orthologs are present primarily in Plasmodium species that infect humans thus making PMT activity a suitable target for drugs to kill different forms of human malaria.We have identified a set of highly active antimalarials using a yeast functional complementation assay. These compounds are potent inhibitors of P. falciparum development in vitro, show little to no toxicity in mammalian cells and display pharmacological properties suitable for further optimization. Biochemical, structural and functional analyses of these compounds and their mode of action will be presented.

Lysophosphatidylcholine acyltransferase1 overexpression promotes oral squamous cell carcinoma progression via enhanced biosynthesis of platelet-activating factor.

BackgroundThe relevance of lysophosphatidylcholine acyltransferase1 (LPCAT1), a cytosolic enzyme in the remodeling pathway of phosphatidylcholine metabolism, in oral squamous cell carcinoma (OSCC) is unknown. We investigated LPCAT1 expression and its functional mechanism in OSCCs.MethodsWe analyzed LPCAT1 mRNA and protein expression levels in OSCC-derived cell lines. Immunohistochemistry was performed to identify correlations between LPCAT1 expression levels and primary OSCCs clinicopathological status. We established LPCAT1 knockdown models of the OSCC-derived cell lines (SAS, Ca9-22) for functional analysis and examined the association between LPCAT1 expression and the platelet-activating factor (PAF) concentration and PAF-receptor (PAFR) expression.ResultsLPCAT1 mRNA and protein were up-regulated significantly (p<0.05) in OSCC-derived cell lines compared with human normal oral keratinocytes. Immunohistochemistry showed significantly (p<0.05) elevated LPCAT1 expression in primary OSCCs compared with normal counterparts and a strong correlation between LPCAT1-positive OSCCs and tumoral size and regional lymph node metastasis. In LPCAT1 knockdown cells, cellular proliferation and invasiveness decreased significantly (p<0.05); cellular migration was inhibited compared with control cells. Down-regulation of LPCAT1 resulted in a decreased intercellular PAF concentration and PAFR expression.ConclusionLPCAT1 was overexpressed in OSCCs and correlated with cellular invasiveness and migration. LPCAT1 may contribute to tumoral growth and metastasis in oral cancer.

Intestinal microbial metabolism of phosphatidylcholine: a novel insight in the cardiovascular risk scenario.

Intestinal microbiota is a "dynamic organ" influencing host metabolism, nutrition, physiology and immune system. Among its several interactions, the role of a phosphatidylcholine metabolite derived by gut flora activity, i.e., trimethylamine-N-oxide (TMAO), allows perceiving a novel insight in the cardiovascular risk scenario, being a strong predictor of this condition. Based on current reports, including the paper of Tang et al., we describe here: the possible role of intestinal microbiota in cardiovascular risk as well as potential interventions to reduce gut flora TMAO production by diet, probiotics and antibiotics. Finally, we highlight the possibility of evaluating, monitoring and modulating TMAO in order to use its serum levels as a marker of cardiovascular risk in the next future, when the need of controlled studies on large series will be satisfied.

Associations of Trimethylamine N-Oxide With Nutritional and Inflammatory Biomarkers and Cardiovascular Outcomes in Patients New to Dialysis

Trimethylamine N-oxide (TMAO) is a product of metabolism of phosphatidylcholine (lecithin) and carnitine by the intestinal microbiome. Elevated serum concentrations of TMAO have been linked to adverse cardiovascular outcomes in the general population. We examined correlates of serum TMAO and the relations among serum TMAO concentrations, all-cause mortality, and cardiovascular mortality and hospitalizations in a nationally derived cohort of patients new to hemodialysis (HD). We quantified serum TMAO by liquid chromatography and online tandem mass spectrometry and assessed nutritional and cardiovascular risk factors in 235 patients receiving HD and measured TMAO in pooled serum from healthy controls. We analyzed time to death and time to cardiovascular death or hospitalization using Cox proportional hazards regression. Serum TMAO concentrations of patients undergoing HD (median, 43μM/L; 25th-75th percentile, 28-67μM/L) were elevated compared with those with normal or near-normal kidney function (1.41±0.49μM/L). TMAO was directly correlated with serum albumin (Spearman rank correlation, 0.24; 95% CI, 0.12-0.35; P <.001), prealbumin (Spearman rank correlation, 0.19; 95% CI, 0.07-0.31; P=.003), and creatinine (Spearman rank correlation, 0.21; 95% CI, 0.08-0.33; P=.002) and inversely correlated with log C-reactive protein (Spearman rank correlation, -0.18; 95% CI, -0.30 to -0.06; P=.005). Higher serum concentrations of TMAO were not significantly associated with time to death (Spearman rank correlation, 0.84; CI, 0.65-1.09; P=.19) or time to cardiovascular hospitalization or cardiovascular death (Spearman rank correlation, 0.88; CI, 0.57-1.35; P=.55). Serum TMAO concentrations were markedly elevated and correlated directly with biochemical markers of nutritional status and inversely with markers of inflammation in patients receiving HD. There was no significant association between serum TMAO concentrations and all-cause mortality, cardiovascular death, or hospitalizations. In patients receiving dialysis-in contrast with the general population-adverse vascular effects of TMAO may be counterbalanced by associations with nutritional or inflammatory status.

Plasma Phosphatidylcholine Alterations in Cystic Fibrosis Patients: Impaired Metabolism and Correlation with Lung Function and Inflammation

Background: Liver impairment, ranging from steatosis to cirrhosis, is frequent in cystic fibrosis (CF) patients and is becoming increasingly significant due to their improved life expectancy. One aspect of hepatic alterations is caused by increased fecal loss of the essential nutrient choline, following enterohepatic bile phosphatidylcholine (PC) cycle impairment. Hepatic PC synthesis, both de novo and via phosphatidylethanolamine-N-methyl-transferase (PEMT), is essential for very low-density lipoprotein (VLDL) secretion. VLDL-PC in particular contributes to the organism's supply with polyunsaturated fatty acids (LC-PUFA), namely arachidonic (C20:4) and docosahexaenoic acid (C22:6). Consequently, choline deprivation and altered hepatic PC metabolism may affect plasma PC homeostasis and extrahepatic organ function. Objectives: To investigate relationships between altered plasma choline and PC homeostasis and markers of lung function and inflammation in CF. To assess alterations in hepatic choline and PC metabolism of CF patients. Design: Quantification of plasma/serum choline and PC species in adult CF patients compared to controls. Correlation of PC with forced expiratory vital capacity (FEV₁) and interleukin 6 (IL-6) concentrations. Analysis of choline and PC metabolism in CF compared to controls, using deuterated choline ([D₉-methyl]-choline) labeling in vivo. Results: Mean choline and PC concentrations in CF patients were lower than in controls. Choline and PC concentrations as well as fractions of C22:6-PC and C20:4-PC correlated directly with FEV₁, but inversely with IL-6. Plasma concentrations of deuterated PC were decreased for both pathways, whereas only in PC synthesized via PEMT precursor enrichment was decreased. Conclusion: In CF patients, hepatic and plasma homeostasis of choline and PC correlate with lung function and inflammation. Impaired hepatic PC metabolism, exemplarily shown in three CF patients, provides an explanation for such correlations. Larger studies are required to understand the link between hepatic PC metabolism and overall clinical performance of CF patients, and the perspective of choline substitution of these patients.