Małgorzata Żendzian-Piotrowska

Inhibition of ceramide de novo synthesis reduces liver lipid accumulation in rats with nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is an insulin resistance‐related hepatic disorder which can transform to cirrhosis. Insulin resistance deregulates hepatic lipid metabolism, leading to accumulation of cytotoxic lipids including ceramide and diacylglycerols. Myriocin, obtained from fungi traditionally used in Chinese medicine in an effort to attain eternal youth, is a potent pharmacological inhibitor of ceramide de novo synthesis. We examined whether inhibition of ceramide de novo synthesis with myriocin ameliorate hepatic lipid accumulation and reverse NAFLD.

Intrathecal increase of sphingosine 1-phosphate at early stage multiple sclerosis

Sphingosine 1-phosphate (S1P) is a pleiotropic mediator that is critically involved in the development of an inflammatory response in various pathological conditions. We hypothesize that during the course of multiple sclerosis (MS) development, chronic inflammation will result in the alteration of S1P levels in blood and cerebrospinal fluid (CSF). We evaluated S1P concentrations in blood and CSF obtained from 66 subjects, including 40 patients diagnosed with MS and 26 subjects of a control group that included patients diagnosed with idiopathic cephalgia and idiopathic (Bells) facial nerve palsy. HPLC techniques were used to determine S1P levels. We found that S1P concentrations in blood of the MS subject group (361.7+/-150.7 nM) did not differ from those of the control group (371.9+/-142.5 nM). However, S1P concentrations in CSF of the MS group were significantly higher (p<0.01) compared to the control group (2.2+/-2.7 versus 0.69+/-1.1 nM). The increase of S1P concentration in CSF of MS subjects suggests that this bioactive lipid is involved in chronic inflammation associated with MS and it may be useful to study S1P in a number of neurodegenerative diseases to provide better understanding of the mechanisms governing their development.

Plasma gelsolin modulates cellular response to sphingosine 1-phosphate.

Hypogelsolinemia is observed in patients with different states of acute or chronic inflammation such as sepsis, rheumatoid arthritis, and multiple sclerosis. In animal models of sepsis, repletion of plasma gelsolin reduces septic mortality. However, the functions of extracellular gelsolin and the mechanisms leading to its protective nature are poorly understood. Potential mechanisms involve gelsolins extracellular actin scavenging function or its ability to bind bioactive lipids or proinflammatory mediators, which would limit inflammatory responses and prevent tissue damage. Here we report that human plasma gelsolin binds to sphingosine 1-phosphate (S1P), a pleiotropic cellular agonist involved in various immune responses, and to its synthetic structural analog FTY720P (Gilenya). The fluorescence intensity of a rhodamine B-labeled phosphatidylinositol 4,5-bisphosphate binding peptide derived from gelsolin and the optical density of recombinant human plasma gelsolin (rhpGSN) were found to decrease after the addition of S1P or FTY720P. Gelsolins ability to depolymerize F-actin also decreased progressively with increasing addition of S1P. Transient increases in phosphorylation of extracellular signal-regulated kinase in bovine aortic endothelial cells (BAECs) after S1P treatment were inhibited by rhpGSN. The ability of S1P to increase F-actin content and the elastic modulus of primary astrocytes and BAECs was also prevented by rhpGSN. Evaluation of S1P and gelsolin levels in cerebrospinal fluid reveals a low concentration of gelsolin and a high concentration of S1P in samples obtained from patients suffering from lymphatic meningitis. These findings suggest that gelsolin-mediated regulation of S1P bioactivity may be important to maintain immunomodulatory balance at inflammatory sites.

High fat diet induces ceramide and sphingomyelin formation in rat's liver nuclei.

Obesity increases the risk for hepatic steatosis. Recent studies have demonstrated that high fat diet (HFD) may affect sphingolipid formation in skeletal muscles, heart, and other tissues. In this work we sought to investigate whether HFD feeding provokes changes in content and fatty acids (FAs) composition of sphingomyelin and ceramide at the level of liver and hepatic nuclei. Furthermore, we investigated whether the ceramide formation is related to the activity of either neutral sphingomyelinase (N-SMase) or acidic sphingomyelinase (A-SMase). Three weeks of HFD provision induced pronounced ceramide and sphingomyelin accumulation in both liver and hepatic nuclei, accompanied by increased activity of N-SMase but not A-SMase. Furthermore, a shift toward greater FAs saturation status in these sphingolipids was also observed. These findings support the conclusion that HFD has a major impact on sphingolipid metabolism not only in the liver, but also in hepatic nuclei.

Antibacterial activity of the human host defence peptide LL-37 and selected synthetic cationic lipids against bacteria associated with oral and upper respiratory tract infections

OBJECTIVES We aim to develop antibacterial peptide mimics resistant to protease degradation, with broad-spectrum activity at sites of infection. METHODS The bactericidal activities of LL-37, ceragenins CSA-13, CSA-90 and CSA-92 and the spermine-conjugated dexamethasone derivative D2S were evaluated using MIC and MBC measurements. Gingival fibroblast counting, interleukin-8 (IL-8) and lactate dehydrogenase (LDH) release from keratinocytes (HaCat) were used to determine effects on cell growth, pro-inflammatory response and toxicity. RESULTS All tested cationic lipids showed stronger bactericidal activity than LL-37. Incubation of Staphylococcus aureus with half the MIC of LL-37 led to the appearance of bacteria resistant to its bactericidal effects, but identical incubations with CSA-13 or D2S did not produce resistant bacteria. Cathelicidin LL-37 significantly increased the total number of gingival fibroblasts, but ceragenins and D2S did not alter gingival fibroblast growth. Cationic lipids showed no toxicity to HaCat cells at concentrations resulting in bacterial killing. CONCLUSIONS These data suggest that cationic lipids such as ceragenins warrant further testing as potential novel antibacterial agents.

Fatty acid transporters involved in the palmitate and oleate induced insulin resistance in primary rat hepatocytes.

To determine the presence and possible involvement of FAT/CD36, FABPpm and FATP‐2, transporters in (i) fatty acids movement across plasma membrane and (ii) an induction of insulin resistance by palmitic (PA) and oleic (OA) fatty acids in primary hepatocytes.

Effect of endurance training on the phospholipid content of skeletal muscles in the rat

Abstract Only few data are available on the effect of training on phospholipid metabolism in skeletal muscles. The aim of the present study was to examine the effect of 6 weeks of endurance training on the content of particular phospholipid fractions and on the incorporation of blood-borne [14C]-palmitic acid into the phospholipids in different skeletal muscles (white and red sections of the gastrocnemius, the soleus and the diaphragm) of the rat. Lipids were extracted from the muscles and separated using thin-layer chromatography into the following fractions: sphingomyelin, phosphatidylcholine, phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, cardiolipin and neutral lipids (this fraction being composed mostly of triacylglycerols). It was found that training did not affect the content of any phospholipid fraction in soleus muscle. It increased the content of sphingomyelin in white gastrocnemius muscle, cardiolipin and phosphatidylethanolamine in red gastrocnemius muscle and phosphatidylinositol in white gastrocnemius muscle and diaphragm. The total phospholipid content in red gastrocnemius muscle of the trained group was higher than in the control group. Training reduced the specific activity of sphingomyelin and cardiolipin in all muscles, phosphatidylcholine in soleus, red, and white gastrocnemius muscles, phosphatidylserine in all muscles, phosphatidylinositol in all except the soleus muscle, and phosphatidylethanolamine in hindleg muscles, but not in the diaphragm compared to the corresponding values in the sedentary group. It was concluded that endurance training affects skeletal muscle phospholipid content and the rate of incorporation of the blood-borne [14C]-palmitic acid into the phospholipid moieties.

Inhibition of ceramide de novo synthesis with myriocin affects lipid metabolism in the liver of rats with streptozotocin-induced type 1 diabetes.

Nowadays diabetes is one of the most common metabolic diseases. Sphingolipids, which are vitally important constituents of intracellular signal transduction pathways, may be among the most pathogenic lipid moieties intermingled in the origin and development of diabetes. It is now well established that inhibition of de novo ceramide synthesis with myriocin exerts positive effects on lipid metabolism and glucose homeostasis in type 2 diabetes mellitus animal models. However, its influence on type I diabetes still remains unknown. Therefore, the scope of this paper is to fulfill that particular gap in our knowledge.

Not only accumulation, but also saturation status of intramuscular lipids is significantly affected by PPARγ activation

Aim:  Intramuscular lipid accumulation has been associated with insulin resistance, and after thiazolidinediones (TZD) treatment, it was shown to be reduced in some, but not all, studies. This work was undertaken to investigate the relationships between intramuscular lipids [free fatty acids (FFA), diacylglycerols (DAG), triacylglycerol (TAG) and phospholipids] and plasmalemmal expression of fatty acid (FA) transporter [FAT/CD36 and FABPpm] in the muscles of varying oxidative capacity, after peroxisome proliferator–activated receptors gamma (PPARγ) activation (rosiglitazone) in an animal model of high‐fat‐diet‐induced insulin resistance. Endurance training was also included to further explore the differences in these relationships.

Impact of morbid obesity and bariatric surgery on antioxidant/oxidant balance of the unstimulated and stimulated human saliva.

OBJECTIVE There is no study evaluating the influence of morbid obesity and bariatric surgery on antioxidant/oxidant homeostasis of the unstimulated and stimulated human saliva. MATERIALS AND METHODS Salivary flow rate, total antioxidant status (TAS), total oxidant status (TOS), oxidative status index (OSI), the total amount of uric acid (UA), polyphenols (pPh), catalase (CAT), superoxide dismutase 2 (SOD2), specific activity of peroxidase (Px), as well as malondialdehyde (MDA), and advanced glycation end products (AGE) concentrations were determined in the unstimulated (UWS) and stimulated (SWS) whole saliva of patients with morbid obesity before and after bariatric surgery. RESULTS In both UWS and SWS, the total amount of TOS, OSI, SOD2, and MDA was statistically higher in patients with morbid obesity as compared to the healthy controls, as well as significantly lower in the patients treated surgically as compared to the obese patients. The median values of the total amount of TAS, CAT, UA, pPh, and specific activity of Px were significantly reduced in UWS and SWS in patients with morbid obesity as compared to the control group and also statistically elevated in patients after bariatric surgery as compared to the patients with morbid obesity. CONCLUSIONS In morbid obesity, reduced unstimulated and stimulated salivary flow can be observed. Bariatric surgery restored only unstimulated salivary flow to normal values. Disturbances in oxidant/antioxidant homeostasis may be observed in UWS and SWS of obese patients before and after treatment.