Małgorzata Knapp

Myocardium of type 2 diabetic and obese patients is characterized by alterations in sphingolipid metabolic enzymes but not by accumulation of ceramide

Data from animal experiments strongly suggest that ceramide is an important mediator of lipotoxicity in the heart and that accumulation of ceramide contributes to cardiomyocyte apoptosis associated with type 2 diabetes and obesity. However, it remains unknown whether a similar relationship is present also in the human heart. Therefore, we aimed to examine whether myocardial apoptosis in obese and type 2 diabetic patients is associated with elevated ceramide level. The study included 11 lean and 26 overweight or moderately obese subjects without (n = 11, OWT) or with (n = 15, T2D-OWT) a history of type 2 diabetes. Samples of the right atrial appendage were obtained from patients at the time of coronary bypass surgery. Compared with lean subjects, the extent of DNA fragmentation (a marker of apoptosis) was significantly higher in the myocardium of OWT patients and increased further in T2D-OWT subjects. However, the content of ceramide and sphingoid bases remained stable. Interestingly, the mRNA level of enzymes involved in synthesis and degradation of ceramide including serine palmitoyltransferase, sphingosine kinase 1, neutral sphingomyelinase, and ceramidases was markedly higher in the myocardium of OWT and T2D-OWT patients compared with lean subjects. Our results indicate that in the human heart, or at least in the atrium, ceramide is not a major factor in cardiomyocyte apoptosis associated with obesity and type 2 diabetes.

Altered sphingolipid metabolism in human endometrial cancer

There is a growing body of evidence indicating that bioactive sphingolipids play a key role in cancer development, progression and metastasis. However, sphingolipid metabolism in malignant tumors is poorly investigated. Therefore, the aim of the present study was to examine the content of selected intermediates of ceramide metabolism and the activity of key enzymes of ceramide de novo synthesis and sphingosine-1-phosphate (S1P) production in the endometrial cancer. The specimens of cancer tissue and healthy endometrium were obtained from women undergoing surgery because of the cancer (n=23) and because of myomas (n=18), respectively. The content of sphinganine, dihydroceramide, ceramide, sphingosine and S1P was measured using high pressure liquid chromatography. The activity of the enzymes was determined using radioactive substrates. It has been found that the content of each examined sphingolipid was markedly elevated in the cancer tissue compared with the healthy endometrium. Namely, sphinganine, sphingosine and dihydroceramide by 3-4.6-fold, ceramide and S1P by 1.9- and 1.6-fold, respectively. Interestingly, the ratio of S1P to ceramide remained stable. The activity of serine palmitoyltransferase and sphingosine kinase 1 was increased by 2.3- and 2.6-fold, respectively. We conclude that endometrial carcinoma is characterized by profound changes in sphingolipid metabolism that likely contribute to its progression and chemoresistance.

Decreased free sphingoid base concentration in the plasma of patients with chronic systolic heart failure

PURPOSE In recent years, the role of sphingolipids in pathophysiology of the heart attracted much attention. Ceramide was found to be involved in the pathogenesis of cardiac dysfunction in animal models of ischemia/reperfusion injury, type 2 diabetes and lipotoxic cardiomyopathy. On the other hand, sphingosine-1-phosphate (S1P), has been shown to possess potent cardioprotective properties. The aim of the present study was to examine plasma concentrations of major sphingolipids in patients with chronic heart failure (HF). MATERIAL AND METHODS The subjects were divided into two major groups: 1) with chronic systolic HF (n=47), and 2) healthy age-matched controls (n=15). Patients in the former group were further divided according to the underlying cause of HF (ischemic heart disease or idiopathic dilated cardiomyopathy, n=29 and 18, respectively). RESULTS Plasma concentrations of S1P, sphinganine-1-phosphate and ceramide observed in both groups of HF patients were very close to these noted in the healthy controls, and no statistically significant differences were found. However, the level of free sphingosine and sphinganine in the plasma of patients with HF decreased by 25 and 27%, respectively, as compared to the control subjects. This effect was independent from the underlying cause of HF as the mean concentrations of these sphingoid bases in patients with ischemic and idiopathic HF were virtually the same. CONCLUSIONS We conclude that chronic heart failure is associated with decreased concentration of free sphingoid bases in the plasma. However, despite lower availability of substrates required for synthesis of cardioprotective sphingoid base-1 phosphates, their plasma level remains stable.

Sustained decrease in plasma sphingosine-1-phosphate concentration and its accumulation in blood cells in acute myocardial infarction.

Sphingosine-1-phosphate (S1P) is a cardioprotective sphingolipid present at high concentration in plasma and blood cells. However, effect of the myocardial infarction on S1P metabolism in blood is poorly recognized. Therefore, we aimed to examine the dynamics of changes in concentration of sphingolipids in blood of patients with acute ST-segment elevation myocardial infarction (STEMI). The study was performed on two groups of subjects: healthy controls (n=32) and patients with STEMI (n=32). In the latter group blood was taken upon admission to intensive heart care unit, and then on the second, fifth and thirtieth day, and approximately two years after admission. STEMI patients showed decreased plasma S1P concentration and accumulation of free sphingoid bases and their 1-phosphates in erythrocytes. This effect was already present upon admission, and was maintained for at least thirty days after the infarction. Interestingly, two years post-infarction plasma S1P level recovered only partially, whereas the content of erythrocyte sphingolipids decreased to the values observed in the control subjects. The most likely reason for the observed reduction in plasma S1P level was its decreased release or increased degradation by vascular endothelial cells, as we did not find any evidence for downregulation of S1P synthesis or release by blood cells. We conclude that patients with STEMI are characterized by marked alterations in sphingolipid metabolism in blood which could be a consequence of the infarction itself, the antiplatelet treatment given or both. Our data suggest that cardioprotective action of S1P may be diminished in patients with acute myocardial infarction.

The value of apelin-36 and brain natriuretic peptide measurements in patients with first ST-elevation myocardial infarction☆

BACKGROUND We aimed to assess apelin-novel endogenous ligand for the angiotensin-like 1 receptor in patients with ST-elevation myocardial infarction (STEMI) and to compare its value with B-type natriuretic peptide (BNP). METHODS In 78 consecutive patients with first STEMI treated with primary PCI, plasma apelin-36 (RIA) and BNP (MEIA) concentrations were measured twice: on admission and on the fifth day of hospitalization. Left ventricle ejection fraction (LVEF) was assessed on admission and composite endpoint (CEP)-after 1 year follow-up. RESULTS During the 5-day interval median plasma BNP level significantly increased and median plasma apelin concentration significantly decreased. BNP, but not apelin, correlated with low LVEF (<50%). In ROC analysis only BNP measurements were diagnostic for low LVEF. In ANOVA test, in patients with CEP, a significant decrease in apelin (but not BNP) concentrations measured in 5-day interval was found. ROC analysis identified only second BNP measurement as significant to estimate adverse outcome 0.627 in the prediction of CEP (95% confidence interval=0.507-0.736). CONCLUSION Following STEMI there is a decrease of plasma apelin-36 concentration and an increase of plasma BNP concentration. BNP is better, than apelin diagnostic value for the detection of impaired LVEF. Both BNP and apelin have prognostic value, although both needs further evaluation.

Serum levels of CD163 and TWEAK in patients with pulmonary arterial hypertension

BACKGROUND Inflammation may play a pivotal role in the pathogenesis of pulmonary arterial hypertension (PAH). We evaluated the concentrations of serum sTWEAK, its scavenger receptor sCD163 and sTWEAK/sCD163 ratio in patients with PAH. DESIGN The study enrolled 26 stable patients with PAH confirmed by right heart catheterization and 24 healthy volunteers matched for age, sex and body weight. All patients underwent transthoracic echocardiography, cardiopulmonary exercise test, 6-min walk test, measurement of lung diffusing capacity for the carbon monoxide (DLCO) and venous blood tests. Concentrations of sTWEAK and sCD163 were determined using ELISA kits. RESULTS The PAH patients were characterized by significantly higher median serum sCD163 levels (1072 vs 890ng/ml, p=0.04) together with lower serum sTWEAK concentrations (200 vs 278.1pg/ml, p=0.003) comparing to control subjects. sTWEAK/sCD163 ratio was therefore significantly lower in PAH group (0.18 vs 0.33, p=0.0005). No correlation was found between sTWEAK and sCD163 concentrations in both groups. We observed statistically significant inverse correlation between peak VO2 consumption and sCD163 concentrations (r=-0.52, p<0.05) and positive with sTWEAK/sCD163 ratio (r=0.45, p<0.05) in PAH group. Moreover, sTWEAK/sCD163 ratio positively correlated with % of predicted values of DLCO (r=0.42, p<0.05). CONCLUSIONS Patients with PAH present altered serum sTWEAK and sCD163 levels. The sTWEAK/sCD163 ratio appears to be a better indicator of the severity of PAH as compared to sTWEAK or sCD163 alone. The exact role of sCD163 or interaction between CD163 and sTWEAK in the initiation or progression of PAH as well as their potential prognostic significance remains to be established.

Influence of atorvastatin on blood pressure control in treated hypertensive, normolipemic patients - An open, pilot study

Abstract Aims. The aim of the study was to determine whether a high dose of atorvastatin lowers blood pressure (BP) in normolipemic patients with well controlled primary arterial hypertension and if this effect is associated with alteration of biomarkers of endothelial function and oxidative stress. In this open-label study, normolipemic patients (n=56) were randomized in the proportion of 2:1 to receive atorvastatin 80 mg daily for 3 months (statin-treated, ST n=39), or to previous therapy (statin-free, SF). BP was measured using a 24-h ambulatory BP measurement device. Plasma levels of 6-keto-PGF1α (prostacyclin metabolite), serum nitric oxide (NO) and levels of autoantibodies immunoglobulin G against oxidatively modified low-density lipoprotein (ox-LDL) were measured. Major findings. The mean change in systolic BP and diastolic BP for ST was – 5.7 mmHg (95% CI –4.1 to –7.2 mmHg) and –3.9 mmHg (95% CI –2.7 to –5.0 mmHg), respectively. Hypotensive statin effect was independent of lipid lowering. No change of BP in SF patients was observed. In ST, prostacyclin metabolites and NO concentrations were not significantly increased and autoantibodies against ox-LDL concentrations did not change. In ST, the decrease in BP correlated with increase in NO and decrease in autoantibodies against ox-LDL. Principal conclusion. High-dose atorvastatin resulted in reduction of BP independently of lipid-lowering effect, changes in endothelial function and oxidative stress, but it was related to the increase in NO and decrease in autoantibodies against ox-LDL. However, because of the open design of the study, these results should be carefully debated.

Enhanced IL-6 trans-signaling in pulmonary arterial hypertension and its potential role in disease-related systemic damage.

BACKGROUND The role of IL-6 in pulmonary arterial hypertension (PAH) has been reported but the prevalence of soluble receptors for IL-6: sIL-6R and sgp130 and its potential role in PAH have not been studied.Our aim was to examine the IL-6 together with the soluble receptors and to assess its relationship with clinical status of PAH patients as well as to assess its potential prognostic significance. METHODS Serum concentrations of IL-6, sIL-6R and sgp130 were quantified by ELISA in 26 patients with PAH and 27 healthy controls and related to functional and biochemical parameters and clinical outcome in PAH group. The PAH patients were followed up for 1 year, noting the end point of clinical deterioration (WHO class change, the need for escalation of therapy) or death. RESULTS The PAH group was characterized by higher median serum IL-6 [2.38 (IQR 1.56-3.75) vs 0.87 (0.63-1.3) pg/ml, p=0.000003] and sIL-6R concentrations [69.7 (IQR 60.4-84.4 vs 45.7 (34.6-70.3) ng/ml, p=0.0036] compared to control subjects. Both groups did not differ in sgp130 concentrations. There were significant correlations in PAH group between IL-6 levels and uric acid, parameters of ventilatory efficiency in cardiopulmonary exercise testing: VE/VO2, VE/VCO2, VE/VCO2 slope and peak PetCO2. sIL-6R levels inversely correlated with LDL cholesterol. After 1 year the clinical deterioration occurred in 11 patients, 15 remained stable. Patients in whom the clinical deterioration occurred showed significantly higher baseline concentrations of IL-6 [3.25 (IQR 2.46-5.4) pg/ml vs 1.68 (1.38-2.78) pg/ml, p=0.004], but not sIL-6R. Median IL-6 ⩾ 2.3 pg/ml (91% sensitivity, 73% specificity) identified subjects with worse clinical course. In the univariate analysis, higher IL-6 level at baseline was associated with increased risk and earlier occurrence of clinical deterioration (HR 1.42, 95%CI 1.08-1.85, p=0.015). CONCLUSIONS IL-6 trans-signaling is enhanced in PAH. Elevated concentration of sIL-6R suggests its potential unfavorable role in systemic amplification of IL-6 signaling in PAH. Levels of IL-6 are associated with clinical indicators of disease severity as well as indirectly with systemic metabolic alterations. IL-6 shows prognostic value regarding predicting clinical deterioration.

Dose-dependent effect of aspirin on the level of sphingolipids in human blood

PURPOSE Aspirin is an antiplatelet drug which is commonly used in secondary prevention in ischemic heart disease and cerebrovascular events, and in newly diagnosed myocardial infarction. The aim of the present study was to examine effect of aspirin on the level of selected sphingolipid intermediates in plasma, erythrocytes and platelets. MATERIAL AND METHOD Forty two healthy volunteers participated in the study. They were divided into two groups. In one group aspirin was given orally, daily, for one week in a dose of 75 mg (n=25). The subjects from the second group received one 300 mg dose of the drug (n=17). In both groups the blood was taken 4h after the last dose of aspirin. The following sphingolipid intermediates were quantified using high-pressure liquid chromatography: sphinganine, sphingosine, sphingosine-1-phosphate (S1P), sphinganine-1-phosphate (SA1P) and ceramide. RESULTS It was found that lower dose of aspirin increased the level of S1P and ceramide in erythrocytes (by 23 and 37%, respectively) having no effect on plasma and platelet sphingolipid levels. Higher dose of the drug reduced S1P and SA1P concentration in the plasma (by 16 and 10%, respectively). CONCLUSION We conclude that aspirin interferes with sphingolipid metabolism in blood and that this effect depends on a dose of the drug. Since S1P is a potent cardioprotectant, the reduction in its plasma concentration after the loading dose of aspirin could be undesired side effect of the drug.

Activity of the kynurenine pathway and its interplay with immunity in patients with pulmonary arterial hypertension

Objective We evaluated blood concentrations of kynurenine pathway metabolites, natural and induced regulatory T cells (nTreg, iTreg), and Th17 cells in order to examine the activity of the kynurenine pathway and its relation to immune status in patients with pulmonary arterial hypertension (PAH). Methods Plasma concentrations of tryptophan, kynurenine, kynurenic acid, anthranilic acid, and 3-hydroxykynurenine were quantified in 26 patients with PAH (vs 30 healthy controls) at baseline and after 6 months, and assessed them in relation to clinical parameters, frequencies of lymphocyte subsets, and outcome. Results The PAH group presented higher concentrations of tryptophan (52.9 (IQR 46.3–57.5) vs 40.3 (35.2–46.3) µmol/L, p=0.00003), kynurenine 2.8 (2.4−3.4) vs 1.9 (1.5–2.3) µmol/L, p=0.000007), kynurenine/tryptophan ratio (0.051 (0.044–0.064) vs 0.043 (0.039–0.055), p=0.03), iTreg frequencies (10.5 (8.8–13.9)% vs 6.8 (5.2–9.5)%, p=0.002) and iTreg/Th17 (1.73 (1.2–2.8) vs 0.93 (0.61–1.27), p=0.003) together with lower ratios of kynurenic acid/kynurenine, 3-hydroxykynurenine/kynurenine, and anthranilic acid/kynurenine. Kynurenine concentrations and kynurenine/tryptophan ratio correlated positively with iTreg/Th17, and inversely with Th17 subsets, whereas kynurenic acid/kynurenine and anthranilic acid/kynurenine ratios correlated positively with Th17. Adverse outcomes occurred in 9 of 26 patients and they showed higher baseline concentrations of kynurenine (3.6 (2.8–4.3) vs 2.7 (2.1–3.2) µmol/L, p=0.033). Median kynurenine values ≥3.4 µmol/L (67% sensitivity, 94% specificity) identified patients with a worse clinical course. Conclusions PAH is characterised by upregulated tryptophan metabolism and enhanced biosynthesis of kynurenine. Elevated kynurenine concentration is associated with an adverse clinical course. Dysregulated immunity, delineated by Treg-Th17 imbalance, is directly related to diverse activation of the kynurenine pathway, indicating the potential interplay between kynurenines and the immune system in PAH.