Apoptosis ; Ceramides ; biosynthesis ; Sphingomyelins ; metabolism

Animals ; Antioxidants ; pharmacology ; Apoptosis ; drug effects ; Atherosclerosis ; prevention & control ; Ceramides ; analysis ; Dietary Fats ; administration & dosage ; Emodin ; pharmacology ; Lipids ; blood ; Male ; Rabbits ; Signal Transduction ; Sphingomyelin Phosphodiesterase ; metabolism ; Sphingomyelins ; metabolism

BACKGROUND: Niemann Pick disease (NP) is a rare, lysosomal storage disorder due to deficiency of the intra-lysosomal enzyme acid sphingomyelinase (ASM) resulting in intracellular accumulation of sphingomyelin. We evaluated a tandem mass spectrometry (MS/MS) method to analyze ASM activity in dried blood spots (DBS) that may be suitable for laboratory diagnosis of NP including high throughput screening of at-risk populations and potentially for newborn screening. METHODS: ASM activity was measured in 3.2 mm punches from DBS. The eluate was incubated with the ASM substrate (N-Hexanoyl-D-erythro-sphingosylphosphorylcholine [C6-sphingomyelin (C29H59N2O6P)]) and an internal standard (N-butyroyl-D-erythro-sphingosine [C4-ceramide (C22H43NO3)]). ASM product and IS were analyzed using MS/MS in multiple reaction monitoring mode for transitions m/z 370.6>264.3 (ASM internal standard) and m/z 398.6>264.3 (ASM product). RESULTS: ASM activities were stable for up to 2 months at or below 4degrees C. Position of the punch in the DBS and/or hematocrit of the DBS had a limited effect on ASM activities. Both intra- and inter-assay variability were below 10%. There was no carry-over. The median ASM activity in 2,085 newborn infants was 9.5 micromol/h/L (mean 10.6) with a SD of 5.06 micromol/h/L. Six of 2,085 (0.3%) infants were found to have ASM activities below the cut-off of 2.5 micromol/h/L. ASM activities were below the cut-off level in all 10 previously diagnosed cases with NP (range: 0.16 to 2.08 micromol/h/L). CONCLUSIONS: This MS/MS method for the measurement of ASM activity in DBS is robust and suitable for laboratory diagnosis of NP.
*Dried Blood Spot Testing ; Hematocrit ; Humans ; Infant, Newborn ; Reference Standards ; Sphingomyelin Phosphodiesterase/*analysis/standards ; Sphingomyelins/metabolism ; Substrate Specificity ; *Tandem Mass Spectrometry/standards

BACKGROUND: Niemann Pick disease (NP) is a rare, lysosomal storage disorder due to deficiency of the intra-lysosomal enzyme acid sphingomyelinase (ASM) resulting in intracellular accumulation of sphingomyelin. We evaluated a tandem mass spectrometry (MS/MS) method to analyze ASM activity in dried blood spots (DBS) that may be suitable for laboratory diagnosis of NP including high throughput screening of at-risk populations and potentially for newborn screening. METHODS: ASM activity was measured in 3.2 mm punches from DBS. The eluate was incubated with the ASM substrate (N-Hexanoyl-D-erythro-sphingosylphosphorylcholine [C6-sphingomyelin (C29H59N2O6P)]) and an internal standard (N-butyroyl-D-erythro-sphingosine [C4-ceramide (C22H43NO3)]). ASM product and IS were analyzed using MS/MS in multiple reaction monitoring mode for transitions m/z 370.6>264.3 (ASM internal standard) and m/z 398.6>264.3 (ASM product). RESULTS: ASM activities were stable for up to 2 months at or below 4degrees C. Position of the punch in the DBS and/or hematocrit of the DBS had a limited effect on ASM activities. Both intra- and inter-assay variability were below 10%. There was no carry-over. The median ASM activity in 2,085 newborn infants was 9.5 micromol/h/L (mean 10.6) with a SD of 5.06 micromol/h/L. Six of 2,085 (0.3%) infants were found to have ASM activities below the cut-off of 2.5 micromol/h/L. ASM activities were below the cut-off level in all 10 previously diagnosed cases with NP (range: 0.16 to 2.08 micromol/h/L). CONCLUSIONS: This MS/MS method for the measurement of ASM activity in DBS is robust and suitable for laboratory diagnosis of NP.
*Dried Blood Spot Testing ; Hematocrit ; Humans ; Infant, Newborn ; Reference Standards ; Sphingomyelin Phosphodiesterase/*analysis/standards ; Sphingomyelins/metabolism ; Substrate Specificity ; *Tandem Mass Spectrometry/standards

This study was to report the effect of Tangshen Formula on phospholipids metabolism in diabetic nephropathy patients. A normal phase-HPLC-TOF/MS method was used in this study for the determination of seven species of phospholipids in human plasma. Then, the concentration changes of potential phospholipids biomarkers were discussed in diabetic nephropathy phase III and phase IV patients among different groups, including before and 3, 6 months after administration of Tangshen Formula. Significant increases of PE750, PI885, PC792, PC826, PC830, PC854 and PC802 levels were observed 6 months after administration of Tangshen Formula and conventional western medicine, as well as a decrease of LPC540 level, when compared with those before medication. Concentrations of all the potential phospholipids biomarkers showed a tendency towards normal levels; however, both the improvement degree and onset time of these compounds were not same. Additionally, Tangshen Formula treatment based on conventional western medicine treatment was more efficient in adjusting the levels of these compounds when compared with western medicine treatment alone, especially for the phase IV patients. These results indicated that Tangshen Formula was capable in regulating and improving phospholipids metabolism in diabetic nephropathy patients, which may be related with the direct or indirect inhibition of protein kinase C pathway and the corresponding reduction of phospholipase A2 activity. Therefore, Tangshen Formula may be used as an effective drug for diabetic nephropathy therapy, at least as an adjunctive therapeutic drug.
Diabetic Nephropathies ; blood ; metabolism ; Double-Blind Method ; Drugs, Chinese Herbal ; isolation & purification ; pharmacology ; Glycerophospholipids ; blood ; Humans ; Lysophosphatidylcholines ; blood ; Phospholipases A2 ; metabolism ; Phospholipids ; blood ; classification ; Plants, Medicinal ; chemistry ; Protein Kinase C ; metabolism ; Signal Transduction ; Sphingomyelins ; blood

Because nerve growth factor (NGF) is elevated during inflammation, plays a causal role in the initiation of hyperalgesia, and is known to activate the sphingomyelin signalling pathway, we examined whether NGF and its putative second messenger, ceramide, could modulate the excitability of capsaicin-sensitive adult sensory neurons. Using the whole-cell patch-clamp recording technique, exposure of isolated sensory neurons to either 100 ng/mL NGF or 1 mmol/L N-acetyl sphingosine (C2-ceramide) produced a 3-4 fold increase in the number of action potentials (APs) evoked by a ramp of depolarizing current in a time-dependent manner. Intracellular perfusion with bacterial sphingomyelinase (SMase) also increased the number of APs suggesting that the release of native ceramide enhanced neuronal excitability. Glutathione, an inhibitor of neutral SMase, completely blocked the NGF-induced augmentation of AP firing, whereas dithiothreitol, an inhibitor of acidic SMase, was without effect. In the presence of glutathione and NGF, exogenous ceramide still enhanced the number of evoked APs, indicating that the sensitizing action of ceramide was downstream of NGF. To investigate the mechanisms of actions for NGF and ceramide, isolated membrane currents were examined. Both NGF and ceramide facilitated the peak amplitude of the TTX-resistant sodium current (TTX-R I(Na)) by approximately 1.5-fold and shifted the activation to more hyperpolarized voltages. In addition, NGF and ceramide suppressed an outward potassium current (I(K)) by ~35%. The inflammatory prostaglandin, PGE2, produced an additional suppression of I(K) after exposure to ceramide (~35%), suggesting that these agents might act on different targets. Based on the existing literature, it is not clear whether this NGF-induced sensitization is mediated by the high-affinity TrkA receptor or the low-affinity p75 neurotrophin receptor. Pretreatment with the p75 blocking antibody completely prevents the NGF-induced increase in the number of APs evoked by the current ramp. Although the sensitization by NGF was blocked, the antibody had no effect on the capacity of ceramide, a putative downstream signalling molecule, to enhance the excitability. Ceramide can be metabolized by ceramidase to sphingosine (Sph) and Sph to sphingosine 1-phosphate (S1P) by sphingosine kinase. It is well established that each of these products of sphingomyelin metabolism can act as intracellular signalling molecules. This raises the question as to whether the enhanced excitability produced by NGF was mediated directly by ceramide or required additional metabolism to Sph and/or S1P. Sph applied externally did not affect the neuronal excitability whereas internally perfused Sph augmented the number of APs evoked by the depolarizing ramp. Furthermore, internally perfused S1P enhanced the number of evoked APs. This sensitizing action of NGF, ceramide, and internally perfused Sph, were abolished by dimethylsphingosine (DMS), an inhibitor of sphingosine kinase. In contrast, internally perfused S1P enhanced the number of evoked APs in the presence of DMS. These observations support the idea that the metabolism of ceramide/Sph to S1P is critical for the sphingolipid-induced modulation of excitability. Thus, our findings indicate that the pro-inflammatory agent, NGF, can rapidly enhance the excitability of sensory neurons. This NGF-induced sensitization is mediated by activation of the sphingomyelin signalling pathway wherein intracellular S1P derived from ceramide, acts as an internal second messenger to regulate membrane excitability, however, the effector system whereby S1P modulates excitability remains undetermined.
Action Potentials ; Animals ; Cells, Cultured ; Ceramides ; pharmacology ; Lysophospholipids ; metabolism ; Nerve Growth Factor ; physiology ; Patch-Clamp Techniques ; Phosphotransferases (Alcohol Group Acceptor) ; metabolism ; Sensory Receptor Cells ; cytology ; Signal Transduction ; Sphingomyelins ; physiology ; Sphingosine ; analogs & derivatives ; metabolism

Plasma sphingomyelin (SM) has been shown to be an independent risk factor for coronary heart disease, and sphingomyelin synthase 2 (SMS2) contributes to de novo SM biosynthesis and plasma membrane SM levels. The aim of the present study is to evaluate the in vivo role of SMS2 deficiency in serum SM metabolism and atherosclerosis (AS) development. We used male SMS2 knockout (SMS2(-/-)) and C57BL/6J (wild-type, WT) mice as experimental and control groups, respectively. Each group was fed high-fat diet (1% cholesterol, 20% leaf fat), as well as bile salt for accelerating the atherosclerotic formation. After three months of feeding, the mice were killed to observe aortic arches and oil red-stained longitudinal sections of thoracoabdominal aortae. Fasting blood samples were taken from the tail vein before and after high-fat diet, and the serum lipid and SM levels were measured by using kits and enzymatic method respectively. Western blot was used to analyze the contents of nuclear factor-kappaB (NFkappaB) p65 subunit in peritoneal macrophages stimulated with lipopolysaccharide (LPS) after high-fat diet. The results showed that after high-fat diet, SMS2(-/-) mice presented decreased atherosclerotic lesions in aortic arch and thoracoabdominal aorta compared with WT mice. Regardless of whether high-fat diet were given or not, SMS2(-/-) mice showed a significant decrease in serum SM level (P<0.05), but no significant changes in serum lipid levels, compared with WT mice. The expressions of NFkappaB p65 were attenuated in macrophages from SMS2(-/-) mice in response to LPS stimulation compared with those of the WT mice. These results suggest that SMS2 deficiency decreases AS and inhibits inflammation in mice. Thus, SMS2 deficiency may be a potential therapeutic strategy.
Animals ; Aorta ; pathology ; Atherosclerosis ; metabolism ; physiopathology ; prevention & control ; Diet, High-Fat ; Dietary Fats ; administration & dosage ; Gene Knockout Techniques ; Inflammation ; prevention & control ; Macrophages, Peritoneal ; enzymology ; pathology ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; NF-kappa B ; metabolism ; Sphingomyelins ; blood ; Transferases (Other Substituted Phosphate Groups) ; genetics