Protective effects of sulforaphane on type 2 diabetes-induced cardiomyopathy via AMPK-mediated activation of lipid metabolic pathways and NRF2 function

BACKGROUND

AMP-activated protein kinase (AMPK), particularly AMPKα2 isoform, plays a critical role in maintaining cardiac homeostasis. It was reported that sulforaphane (SFN) prevented type 2 diabetes (T2D)-induced cardiomyopathy accompanied by the activation of AMPK; In this study, AMPK's pivotal role in SFN-mediated prevention against T2D-induced cardiomyopathy was tested using global deletion of AMPKα2 gene (AMPKα2-KO) mice.

METHODS AND RESULTS

T2D was established by feeding 3-month high-fat diet (HFD) to induce insulin resistance, followed by an intraperitoneal injection of streptozotocin (STZ) to induce mild hyperglycemia in both AMPKα2-KO and wild-type (WT) mice. Then both T2D and control mice were subsequently treated with or without SFN for 3 months while continually feeding HFD or normal diet. Upon completion of the 3-month treatment, five mice from each group were sacrificed as a 3-month time-point (3 M). The rest continued normal diet or HFD until terminating study at the sixth month (6 M) of diabetes. Cardiac function was examined with echocardiography before sacrifice at both 3 M and 6 M. SFN prevented T2D-induced progression of cardiac dysfunction, remodeling (hypertrophy and fibrosis), inflammation, and oxidative damage in wild-type diabetic mice, but not in AMPKα2-KO mice. Mechanistically, SFN prevented T2D-induced cardiomyopathy not only by improving AMPK-mediated lipid metabolic pathways, but also enhancing NRF2 activation via AMPK/AKT/GSK3β pathway. However, these improving effects of SFN were abolished in AMPKα2-KO diabetic mice.

CONCLUSIONS

AMPK is indispensable for the SFN-induced prevention of cardiomyopathy in T2D, and the activation of NRF2 by SFN is mediated by AMPK/AKT/GSK3β signaling pathways.

PPAR δ inhibition protects against palmitic acid-LPS induced lipidosis and injury in cultured hepatocyte L02 cell

Background: Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, and its pathogenesis and mechanism are intricate. In the present study, we aimed to evaluate the role of PPAR δ in LPS associated NAFLD and to investigate the signal transduction pathways underlying PPAR δ treatment in vitro. Material and Methods: L02 cells were exposed to palmitic acid (PA) and/or LPS in the absence or presence of PPAR δ inhibition and/or activation. Results: LPS treatment markedly increased lipid deposition, FFA contents, IL-6 and TNF-α levels, and cell apoptosis in PA treatment (NAFLD model). PPAR δ inhibition protects L02 cells against LPS-induced lipidosis and injury. Conversely, the result of PPAR δ activation showed the reverse trend. LPS+PA treatment group significantly decreases the relative expression level of IRS-1, PI3K, AKT, phosphorylation of AKT, TLR-4, MyD88, phosphorylation of IKKα, NF-κB, Bcl-2 and increases the relative expression level of Bax, cleaved caspase 3 and cleaved caspase 8, compared with the cells treated with NAFLD model. PPAR δ inhibition upregulated the related proteins' expression level in insulin resistance and inflammation pathway and downregulated apoptotic relevant proteins. Instead, PPAR δ agonist showed the reverse trend. Conclusion: Our data show that PPAR δ inhibition reduces steatosis, inflammation and apoptosis in LPS-related NAFLD damage, in vitro. PPAR δ may be a potential therapeutic implication for NAFLD.

Ectopic Lipid Deposition Is Associated With Insulin Resistance in Postmenopausal Women

CONTEXT

Menopause is associated with an increased incidence of insulin resistance and diabetes.

OBJECTIVE

The aim of this study was to explore the lipid deposition in liver and skeletal muscle and investigate the association with insulin sensitivity in postmenopausal and premenopausal women.

DESIGN AND SETTING

Single-center cross-sectional study of 55 healthy women between 45 and 60 years of age. We measured lipid deposition in the liver with magnetic resonance spectroscopy, intramuscular and intra-abdominal lipid deposition with MRI, body composition with a dual-energy X-ray absorptiometry scan, and insulin sensitivity with the composite Matsuda Index.

OUTCOME MEASURES

We studied the association between fat distribution, ectopic lipid deposition, and insulin sensitivity in pre- and postmenopausal women.

RESULTS

Postmenopausal women had an increased lipid deposition in the liver [0.68% (0.44 to 0.99) vs 0.49% (0.38 to 0.64), P = 0.01] and skeletal muscle [3% (2 to 4) vs 2% (1 to 3), P = 0.001] and had a 28% lower Matsuda insulin sensitivity index during an oral glucose tolerance test (6.31 ± 3.48 vs 8.78 ± 4.67, P = 0.05) compared with premenopausal women. Total fat mass and leg fat mass were stronger predictors of ectopic lipid deposition, and visceral fat mass was a stronger predictor of both ectopic lipid deposition and insulin resistance in postmenopausal women compared with premenopausal women.

CONCLUSIONS

For a given subcutaneous and visceral fat depot size, postmenopausal women show increased ectopic lipid deposition and insulin resistance compared with premenopausal women. It is suggested that lipid deposition in liver and skeletal muscle may represent important mechanistic links between the changes in fat depots and the increased incidence of insulin resistance seen after menopause.

Simvastatin ameliorates renal lipidosis through the suppression of renal CXCL16 expression in mice with adriamycin-induced nephropathy

AIMS

To investigate the roles of CXCL16 and ox-LDL in adriamycin (ADR)-induced nephropathy mice and to explore the mechanism of simvastatin on the renal protective effects of ADR nephropathy.

METHODS

Fifteen male Balb/c mice were randomly divided into normal control (NC), ADR nephropathy and simvastatin-treated ADR nephropathy (ADR-SIM) groups. ADR nephropathy was induced by a single intravenous injection of ADR into the tail vein. All mice were sacrificed at the end of the 7th week, with the blood, 24-h urine and kidneys collected. The levels of ox-LDL and total cholesterol in the serum, the serum CXCL16, ox-LDL and NF-κB expression were detected.

RESULTS

Compared with the NC group, the levels of serum total cholesterol and ox-LDL in the ADR and ADR-SIM groups were significantly higher, the level of serum albumin was significantly lower and the expression of CXCL16, ox-LDL and NF-κB in the renal tissue of ADR and ADR-SIM groups was significantly increased. Compared with the ADR group, the expressions of renal CXCL16, ox-LDL and NF-κB in the ADR-SIM group were significantly decreased. Levels of serum total cholesterol and ox-LDL were not significantly different between the two groups.

CONCLUSIONS

Simvastatin exerts a protective effect on renal function and structure in mice with ADR nephropathy. The beneficial effects of simvastatin might be related to the decreasing expression of CXCL16 in glomerular podocytes followed by the decreasing endocytosis of ox-LDL in podocytes and inhibition of NF-κB pathway activation.

[Collagen fiber pathology in atherosclerotic plaques of the coronary arteries in ischemic heart disease]

Structure-metabolic changes of collagen fibers (CF) in atherosclerosis plaques of the coronary arteries in the conditions of ischemic heart disease (IHD) have been studied. Segments of the coronary arteries were received from 68 men after a coronary artery bypass grafting. CF was study with using of the Van Gieson's and the Masson's methods. Histologic slices were studied by polarization microscopy. The atherosclerosis plaques with IHD were notable for lipidosis of CF. We've suspected lipidosis of CF is a crucial factor for the development of atherosclerosis plaques instability. Evident lipidosis of CF was attended with destructive changes probably resulted in accumulation of atheromatous mass in atherosclerosis plaques.

Lysosomal lipid storage diseases

Lysosomal lipid storage diseases, or lipidoses, are inherited metabolic disorders in which typically lipids accumulate in cells and tissues. Complex lipids, such as glycosphingolipids, are constitutively degraded within the endolysosomal system by soluble hydrolytic enzymes with the help of lipid binding proteins in a sequential manner. Because of a functionally impaired hydrolase or auxiliary protein, their lipid substrates cannot be degraded, accumulate in the lysosome, and slowly spread to other intracellular membranes. In Niemann-Pick type C disease, cholesterol transport is impaired and unesterified cholesterol accumulates in the late endosome. In most lysosomal lipid storage diseases, the accumulation of one or few lipids leads to the coprecipitation of other hydrophobic substances in the endolysosomal system, such as lipids and proteins, causing a "traffic jam." This can impair lysosomal function, such as delivery of nutrients through the endolysosomal system, leading to a state of cellular starvation. Therapeutic approaches are currently restricted to mild forms of diseases with significant residual catabolic activities and without brain involvement.

[Pathogenesis of lipid storage diseases]

Lipidoses are rare genetic disorders characterized by defects of the digestive system that impair the way the body uses dietary fat. When the body is unable to properly digest fats, lipids such as cholesterol, sphingolipids or glycolipids may accumulate in body tissues in abnormal amounts. It has been also suggested that molecular mechanisms leading to development of human diseases, including obesity, diabetes type II and atherosclerosis, consist of impaired transport and storage of lipids, as well as disturbed structure and function of lipid membrane microdomains. In this review we discuss probable mechanisms, including role of lipid membrane microdomains, which may participate in pathogenesis of lipid storage diseases such as Niemann-Pick type A/B and type C, as well as Gaucher type I diseases.

Amiodarone attenuates apoptosis, but induces phospholipidosis in rat alveolar epithelial cells

Amiodarone-induced pulmonary toxicity is a serious side-effect, but the underlying molecular mechanisms remain unclear. We examined phospholipidosis and apoptosis in rat alveolar epithelial cells after medium-term oral amiodarone treatment. Amiodarone (30 mg/kg daily, a dosage corresponding to that used clinically) or vehicle was administered by gavage in 33 Wistar rats for two weeks. Apoptosis was assessed by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labelling (TUNEL) and the expression of apoptosis- and phospholipidosis-related proteins was measured by immunohistochemistry. Amiodarone decreased phospholipase-C-γ1 and increased phosphatidylinositol-(4,5)-bisphosphate, resulting in phospholipidosis, evidenced by the appearance of intracellular inclusion bodies with a multi-lamellated interior. Amiodarone exerted two opposite effects on apoptosis; compared to controls, the expression of activated-caspase-8 was higher in treated rats, while the expression of apoptosis inhibitors survivin, Bcl-2 and c-Flip was lower. On the other hand, the expression of activated-caspase-3 was lower after treatment. Overall, amiodarone attenuated apoptosis, evidenced by fewer TUNEL-positive cells. Medium-term oral amiodarone administration induced phospholipidosis in rat alveolar epithelial cells. Although such treatment decreased anti-apoptotic proteins, apoptosis was attenuated via a decrease in the caspase-3 pathway. These findings improve current understanding on the mechanisms underlying amiodarone-induced pulmonary toxicity.

Protective effect of Chinese prescription Kangen-karyu and its crude drug Tanjin against age-related lipidosis in rats

We have investigated the effect of the Chinese prescription Kangen-karyu and its crude drug Tanjin against age-related lipidosis in-vivo in a rat model. The serum and hepatic triglyceride levels were remarkably elevated in 12-month-old compared with two-month-old rats. However, the administration of Kangen-karyu and Tanjin extracts significantly decreased these levels. This suggested a protective role against related pathological conditions as well as hyperlipidaemia. On the other hand, the reduction of the levels of adiponectin in serum with ageing did not show significant changes in rats given diets supplemented with Kangen-karyu and Tanjin extracts. Furthermore, the expression of transcription factors in nuclear hepatic tissue related to lipid metabolism was investigated. The decline in the expression of nuclear peroxisome proliferator-activated receptor α protein in hepatic tissue with age was ameliorated by the administration of Kangen-karyu and Tanjin supplements. On the other hand, the overexpression of sterol regulatory element-binding proteins (SREBP)-1 and SREBP-2 in old rats compared with young rats showed a tendency to decrease with Kangen-karyu and Tanjin administration. The decline of hepatic function with ageing was attenuated by Kangen-karyu and Tanjin, suggesting the beneficial role of Kangen-karyu and Tanjin on lipid metabolism through the improvement of hepatic function. This study has demonstrated that Kangen-karyu and Tanjin inhibited the accumulation of triglyceride with regulation of related protein expressions and they improved hepatic function. Evidence has been provided for the anti-ageing activity of Kangen-karyu and its crude drug Tanjin against age-related lipidosis.

Bis(monoacylglycero)phosphate, a peculiar phospholipid to control the fate of cholesterol: Implications in pathology

Bis(monoacylglycero)phosphate (BMP) is a structural isomer of phosphatidylglycerol that exhibits an unusual sn1:sn1' stereoconfiguration, based on the position of the phosphate moiety on its two glycerol units. Early works have underlined the high concentration of BMP in the lysosomal compartment, especially during some lysosomal storage disorders and drug-induced phospholipidosis. Despite numerous studies, both biosynthetic and degradative pathways of BMP remained not completely elucidated. More recently, BMP has been localized in the internal membranes of late endosomes where it forms specialized lipid domains. Its involvement in both dynamics and lipid/protein sorting functions of late endosomes has started to be documented, especially in the control of cellular cholesterol distribution. BMP also plays an important role in the late endosomal/lysosomal degradative pathway. Another peculiarity of BMP is to be naturally enriched in docosahexaenoic acid and/or to specifically incorporate this fatty acid compared to other polyunsaturated fatty acids, which may confer specific biophysical and functional properties to this phospholipid. This review summarizes and updates our knowledge on BMP with an emphasis on its possible implication in human health and diseases, especially in relation to cholesterol homeostasis.

Observations on lipid composition with particular reference to cardiolipin of rat heart after feeding rapeseed oil

The influence of dietary rapeseed oil on the lipid classes and fatty acid pattern of rat heart homogenate and mitochondria has been investigated after feeding a diet with 9.8 weight- % erucic acid for 10 days and 1.4 and 2.6% erucic acid for 28 days. The rats treated with 9.8% erucic acid showed a significant increase in the triglycerides of the heart mitochondria. This tendency was much less pronounced in rats treated with 1.4 resp. 2.6% erucic acid. These results confirm those of other investigators. A slight increase in the cholesterol esters of the mitochondria could be seen in all the treated rats. The total phospholipids were decreased in the experiment with 9.8% erucic acid and slightly increased in experiments with 1.4 and 2.6% erucic acid. The concentration of phosphatidylcholine showed a tendency to increase and the concentration of phosphatidylethanolamine to decrease in the experiment with 9.8% erucic acid in the diet. The concentration of cardiolipin was mainly unchanged. In all experiments the triglycerides of the heart mitochondria showed a high content of erucic acid. The fatty acids of the cholesterol esters of the heart mitochondria were also influenced of dietary rapeseed oil but to a less extent than the triglycerides. The fatty acids of phosphatidylcholine, phosphatidylethanolamine and cardiolipin were all influenced by the dietary rapeseed oil, but the erucic acid seemed to have a specific affinity to cardiolipin. Cardiolipin of rat heart mitochondria was isolated and identified with gas chromatography and mass spectrometry. The isolated cardiolipin was found to contain 12 per cent erucic acid after feeding 9.8% erucic acid as rapeseed oil for 10 days. Similar results were obtained after feeding glyceryl trierucate for 5 days to rats. The incorporation of erucic acid into cardiolipin was followed by a corresponding decrease of linoleic acid. This observation is of great interest because the molecular structure of fatty acids in lipid molecules has a profound influence of the packing of these molecules in a bilayer. Since cardiolipin is a component of the inner membrane of mitochondria its high affinity for erucic acid might influence the normal function of the inner membrane of heart mitochondria.

Studies of the mode of action of erucic acid on heart metabolism

The effects of erucic acid on the oxidative metabolism of rat-heart mitochondria have been investigated using intact animals, perfused beating heart, isolated mitochondria and mitochondrial extracts. Feeding rats with a diet containing erucic acid was found to lead to a diminished ability of the isolated heart mitochondria to oxidize various substrates, in accordance with previous reports (Houtsmuller et al., Biochim. Biophys. Acta 218 (1970) 564). This effect was almost pronounced with palmitylcarnitine as substrate, in which case the rate of oxidation was decreased by more than 50% at such a low erucic acid content in the diet as 1.4% given over 2-4 weeks. Oxidation of palmitylcarnitine was also found to be inhibited when erucylcarnitine was added to isolated heart mitochondria from control animals, in agreement with earlier observations (Christophersen and Bremer, FEBS Lett. 23 (1972) 230; Biochim. Biophys. Acta 280 (1972) 506). The inhibition was accompanied by a decrease in the rate and extent of reduction of mitochondrial flavoprotein. Experiments with perfused beating rat-heart likewise revealed an inhibition of flavoprotein reduction, as well as nicotinamide nucleotide reduction, when erucate was added to the perfusing medium of the beating heart respiring with oleate--but not with octanoate--as substrate. These data together with those earlier published in the literature indicate that erucic acid may interfere with the enzyme system involved in the mitochondrial oxidation of long-chain fatty acids, probably at the level of acyl-CoA dehydrogenase. Kinetic data supporting this conclusion, obtained with extracts of rat-heart mitochondria containing the acyl-CoA dehydrogenase and electron-transferring flavoprotein system, are presented. The possible implications of these results for the known effect of dietary erucic acid in causing an accumulation of fat in the heart are discussed.

Phenylacetylglycine, a putative biomarker of phospholipidosis: Its origins and relevance to phospholipid accumulation using amiodarone treated rats as a model

Amiodarone was given to male Sprague-Dawley rats at a dose of 150 mg kg(-1) day(-1) for 7 consecutive days to induce phospholipidosis in the lungs of treated rats. Amiodarone was given alone or concurrently with phenobarbitone. Animals given amiodarone had raised total phospholipid in serum, lung and lymphocytes, and elevated lyso(bis)phosphatidic acid (LBPA) in all tissues. Urinary and plasma phenylacetylglycine (PAG) and hepatic portal:aortal phenylacetate (PA) ratio were increased, whereas hepatic phenylalanine hydroxylase (PAH) activity and plasma phenylalanine:tyrosine ratio were not affected. Phenobarbitone treatment increased hepatic total P450 content and induced 7-pentoxyresorufin O-dealkylatian (PROD) activity, as expected, but had no effect on any other biochemical parameter. Plasma amiodarone concentration was reduced in rats co-administered both drugs and phospholipid accumulation in target tissues was attenuated compared with rats treated with amiodarone alone. However, phenobarbitone co-administration failed to alter the magnitude of response with regards to urinary PAG excretion and plasma concentration of its precursors after amiodarone treatment. Increased intestinal absorption of PAG precursors probably resulted in the raised urinary PAG after amiodarone treatment. Urinary PAG correlated weakly with serum, lymphocyte and lung phospholipids. However, urinary PAG excretion was similar in rats dosed solely with amiodarone or in combination with phenobarbitone, despite the fact that the degree of phospholipid accumulation was far less in rats given the combined treatment. Nevertheless, urinary PAG was raised only in animals exhibiting abnormal phospholipid accumulation in target tissues and may thus be useful as a surrogate biomarker for phospholipidosis.

Phospholipid membrane abnormalities and reduced niacin skin flush response in schizophrenia

OBJECTIVES

Reduced n-3 and n-6 polyunsaturated fatty acids (PUFAs) content in red blood cell (RBC) membranes and abnormal membrane phospholipid metabolism were repeatedly implicated in the etiology of schizophrenia.

FINDINGS

Prenatal and perinatal depletion of PUFAs interferes with normal brain development and function. The lack of docosahexaenoic acid - DHA in the brain is reflected in lower membrane DHA/AA (AA - arachidonic acid) ratio, increased activity of AA-metabolizing enzymes, and disturbance of downstream metabolic pathways involved in signaling, growth modulation, brain glucose uptake, immune functions, neurotransmission, synaptogenesis and neurogenesis. Preliminary high-throughput metabolomic studies revealed abnormal biochemical profile in patients with schizophrenia or brief psychotic disorder when compared to healthy controls. The results of both metabolomic and proteomic studies pointed to energy metabolism and lipid biosynthesis being impaired in schizophrenia. The usefulness of antipsychotic medication and supplementation with PUFAs in reverting to the normal metabolic state has been suggested in early treatment of the first psychotic episode. Abnormalities of phospholipid metabolism can be also detected as attenuated niacin skin flush response in the variety of neuropsychiatric disorders.

CONCLUSIONS

Disturbances of lipid homeostasis could represent biochemical markers in the preclinical phase of neuropsychiatric illnesses and could serve as triggers in genetically vulnerable individuals. The assessment of patients' lipid status may also help in monitoring the course of the disease and treatment response. In this regard, simple, cheap and fast niacin skin flush test might be valuable. It might help in diagnosis of adolescents and young adults with psychotic behaviour, or in defining the necessity for long-term antipsychotic therapy. Along with antipsychotic medication schizophrenic patients need specific medical nutrition therapies.

Neuronal and glial accumulation of alpha- and beta-synucleins in human lipidoses

A number of the lysosomal storage diseases that have now been characterized are associated with intra-lysosomal accumulation of lipids, caused by defective lysosomal enzymes. We have previously reported neuronal accumulation of both alpha- and beta-synucleins in brain tissue of a GM2 gangliosidosis mouse model. Although alpha-synuclein has been implicated in several neurodegenerative disorders including Parkinson's disease, dementia with Lewy bodies and multiple system atrophy, its functions remain largely unclear. In our present study, we have examined a cohort of human lipidosis cases, including Sandhoff disease, Tay-Sachs disease, metachromatic leukodystrophy, beta-galactosialidosis and adrenoleukodystrophy, for the expression of alpha- and beta-synucleins and the associated lipid storage levels. The accumulation of alpha-synuclein was found in brain tissue in not only cases of lysosomal storage diseases, but also in instances of adrenoleukodystrophy, which is a peroxisomal disease. alpha-synuclein was detected in both neurons and glial cells of patients with these two disorders, although its distribution was found to be disease-dependent. In addition, alpha-synuclein-positive neurons were also found to be NeuN-positive, whereas NeuN-negative neurons did not show any accumulation of this protein. By comparison, the accumulation of beta-synuclein was detectable only in the pons of Sandhoff disease cases. This differential accumulation of alpha- and beta-synucleins in human lipidoses may be related to functional differences between these two proteins. In addition, the accumulation of alpha-synuclein may also be a condition that is common to lysosomal storage diseases and adrenoleukodystrophies that show an enhanced expression of this protein upon the elevation of stored lipids.

Urinary metabolic fingerprinting for amiodarone-induced phospholipidosis in rats using FT-ICR MS

In the research and development for new therapeutic compounds, there has been a focus on detecting the changes of metabolites induced by drug administration and finding surrogate markers to assess its toxicity. We examined the suitability of urinary metabolic fingerprinting using Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) for toxicological assessment in the amiodarone (AMD)-induced phospholipidosis (PLD) rat model. There were more than 400 different ion peaks detected in the negative ion mode analysis with FT-ICR MS. About 20% of the detected ions were altered more than 1.5 fold by AMD-treatment. On the scores plot of principal component analysis (PCA), the ion profiles of the treated were separated time-dependently. The loading plot revealed that the metabolites causing PCA results were m/z 178.05101, 191.01979, 192.06676, 212.00239, 258.9944 and 283.0820. The ion at m/z 178.05101 is considered to be hippurate (HA), 192.06676 is phenylacetylglycine (PAG) and 212.00239 is indican (IDN). These results indicate that PAG, IDN and HA are biomarkers for AMD-induced PLD in urinary metabolic fingerprinting using FT-ICR MS. These markers may be useful for evaluation of chemicals, which have the potential to induce PLD.

Cell-based fluorescence assay for evaluation of new-drugs potential for phospholipidosis in an early stage of drug development

To evaluate new-drugs potential for phospholipidosis (PL), we developed a cell-based fluorescence assay using a fluorescent-labeled phospholipid analogue (NBD-PE). CHL/IU cells derived from newborn hamster lung were exposed to positive reference compounds (amiodarone, imipramine, chloroquine, propranolol, chlorpromazine and amantadine) in the presence of NBD-PE, and the level of PL, as indicated by accumulation of fluorescent inclusions in the cytoplasm, was evaluated using fluorescence microscopy and fluorometry. All positive reference compounds induced accumulation of fluorescent inclusions in a concentration-dependent manner with an increase in fluorescence intensity. Fluorescence microscopically, the positive dose of test compound was determined as the concentration with a grade equivalent to or above that of 3.13 microM of amiodarone. Based on this criterion, 8 of 20 test compounds including PL-positive or -negative compounds were judged positive that were concurrent with the pathological results from rat toxicity studies. Furthermore, a positive criterion for fluorometry was decided as equivalent to or above 25% of maximum intensity induced by 1.56-25.0 microM amiodarone. In comparison of fluorometry methods with fluorescence microscopy method, 19 of 20 compounds were judged same. From these findings, we concluded that the assay developed in this study is a rapid and reliable method to predict new-drugs potential for PL at an early stage of drug development.

In Vitro Detection of Drug-Induced Phospholipidosis Using Gene Expression and Fluorescent Phospholipid Based Methodologies

Phospholipidosis (PLD) is characterized by the excessive intracellular accumulation of phospholipids. It is well established that a large number of cationic amphiphilic drugs have the potential to induce PLD. In the present study, we describe two facile in vitro methods to determine the PLD-inducing potential of a molecule. The first approach is based on a recent study by (Sawada et al., 2005, Toxicol. Sci. 83, 282-292) in which 17 genes were identified as potential biomarkers of PLD in HepG2 cells. To confirm the utility of this gene panel, we treated HepG2 cells with PLD-positive and -negative compounds and then analyzed gene expression using real-time PCR. Our initial analysis, which used a single dose of each drug, correctly identified five of eight positive compounds and four of four negative compounds. We then increased the doses of the three false negatives (amiodarone, tamoxifen, and loratadine) and found that the changes in gene expression became large enough to correctly identify them as PLD-inducing drugs. Our results suggest that a range of concentrations should be used to increase the accuracy of prediction in this assay. Our second approach utilized a fluorescently labeled phospholipid (LipidTox) which was added to the media of growing HepG2 cells along with compounds positive and negative for PLD. Phospholipid accumulation was determined using confocal microscopy and, more quantitatively, using a 96-well plate assay and a fluorescent plate reader. Using an expanded set of compounds, we show that this assay correctly identified 100% of PLD-positive and -negative compounds. Dose-dependent increases in intracellular fluorescent phospholipid accumulation were observed. We found that this assay was less time consuming, more sensitive, and higher throughput than gene expression analysis. To our knowledge, this study represents the first validation of the use of LipidTox in identifying drugs that can induce PLD.

Bilateral severe progressive idiopathic lipid keratopathy

PURPOSE

To report a case with bilateral progressive lipid keratopathy.

METHODS

A 44-year-old healthy man without previous ocular disease presented with bilateral lipid keratopathy which was more severe in his right eye. Evidence of hyperlipidemia or clinical corneal neovascularization was not apparent.

RESULTS

Penetrating keratoplasty (PKP) was performed, initially in the right eye and four years later in the left eye. Histochemical examination showed focal stromal vascularization and staining for lipids. During the follow-up period, one episode of graft rejection occurred in each eye; both responded to systemic steroid therapy.

CONCLUSION

Severe bilateral progressive lipid degeneration can develop in previously healthy corneas in healthy patients without underlying pathology. The nature of the process remains unclear. When PKP is performed and neovascularization is identified in the removed corneal button, close follow-up is advisable because corneal grafts can be prone to rejection.

Determination of Phospholipidosis Potential Based on Gene Expression Analysis in HepG2 Cells

Phospholipidosis (PLD) is characterized by an intracellular accumulation of phospholipids in lysosomes and the concurrent development of concentric lamellar bodies. Recently, H. Sawada et al. (2005, Toxicol. Sci. 83, 282-292) identified 17 genes as potential biomarkers of PLD in HepG2 cells. The present study was undertaken to determine if this set of genes measured by quantitative PCR could be validated in the same cell line. The objective was also to investigate the dose-response relationship to further validate the assay and to select the concentrations to use for screening activities. In a first experiment (one concentration tested), out of the 17 genes, the best gene biomarkers of PLD (i.e., 11 genes) were selected for practical screening reasons. Based on these genes, 91.6% (i.e., 11 of 12) of the compounds known to induce PLD were identified as positive and all the negative compounds (i.e., five of five) were also confirmed. When the data obtained in the first experiment were compared to the data by Sawada et al., (2005) the coefficient of correlation calculated was slightly higher than 75%. In the second experiment (26 compounds [all 17 compounds from the first experiment plus 9 other compounds] tested at a minimum of three concentrations), 93.3% (14/15) of the compounds known to induce PLD were identified as such and all the negative controls (six compounds) were also confirmed. Three compounds likely to induce PLD were identified as positive in our assay. Finally, two compounds for which no data are available were also tested. When both experiments 1 and 2 were compared, the coefficient of correlation for 16 compounds tested at the same concentrations reached 87.7%. In conclusion, the present study further confirms the utility of gene expression in HepG2 cells to identify a potential to induce PLD. Finally, based on the data presented, researchers are encouraged to use a range of minimum three concentrations (e.g., 12.5, 25, and 50 microM) to screen for PLD in the human HepG2 cell line.

Demonstration of Lysosomal Localization for the Mammalian Ependymin-related Protein Using Classical Approaches Combined with a Novel Density Shift Method

Most newly synthesized soluble lysosomal proteins are delivered to the lysosome via the mannose 6-phosphate (Man-6-P)-targeting pathway. The presence of the Man-6-P post-translational modification allows these proteins to be affinity-purified on immobilized Man-6-P receptors. This approach has formed the basis for a number of proteomic studies that identified multiple as yet uncharacterized Man-6-P glycoproteins that may represent new lysosomal proteins. Although the presence of Man-6-P is suggestive of lysosomal function, the subcellular localization of such candidates requires experimental verification. Here, we have investigated one such candidate, ependymin-related protein (EPDR). EPDR is a protein of unknown function with some sequence similarity to ependymin, a fish protein thought to play a role in memory consolidation and learning. Using classical subcellular fractionation on rat brain, EPDR co-distributes with lysosomal proteins, but there is significant overlap between lysosomal and mitochondrial markers. For more definitive localization, we have developed a novel approach based upon a selective buoyant density shift of the brain lysosomes in a mutant mouse lacking NPC2, a lysosomal protein involved in lipid transport. EPDR, in parallel with lysosomal markers, shows this density shift in gradient centrifugation experiments comparing mutant and wild type mice. This approach, combined with morphological analyses, demonstrates that EPDR resides in the lysosome. In addition, the lipidosis-induced density shift approach represents a valuable tool for identification and validation of both luminal and membrane lysosomal proteins that should be applicable to high throughput proteomic studies.

Drug-induced phospholipidosis

Drug-induced phospholipidosis is characterized by intracellular accumulation of phospholipids with lamellar bodies, most likely from an impaired phospholipid metabolism of the lysosome. Organs affected by phospholipidosis exhibit inflammatory reactions and histopathological changes. Despite significant advances in the understanding of drug-altered lipid metabolism, the relationship between impaired phospholipid metabolism and drug-induced toxicity remains enigmatic. Here we review molecular features of inheritable lysosomal storage disorders as a molecular mimicry of drug-induced phospholipidosis for an improved understanding of adverse drug reaction.

Drug-induced phospholipidosis: issues and future directions

Numerous drugs containing a cationic amphiphilic structure are capable of inducing phospholipidosis in cells under conditions of in vivo administration or ex vivo incubation. The principal characteristics of this condition include the reversible accumulation of polar phospholipids in association with the development of unicentric or multicentric lamellated bodies within cells. There is an abundance of data providing an understanding of potential mechanisms for the induction of phospholipidosis; however, the process is likely to be complex and may differ from one drug to another. The functional consequences of the presence of this condition on cellular or tissue function are not well understood. The general consensus is that the condition is an adaptive response rather than a toxicological manifestation; however, additional studies to examine this question are needed. Until this issue is resolved, concerns about phospholipidosis will continue to exist at regulatory agencies. Procedures for the screening of potential phospholipogenic candidate compounds are available. In contrast, a clear need exists for the identification of valid biomarkers to assess the development of phospholipidosis in preclinical and clinical studies.

A clinical flow cytometric biomarker strategy: validation of peripheral leukocyte phospholipidosis using Nile red

Phospholipidosis, or intracellular accumulation of phospholipids, is caused by specific classes of xenobiotics. This phenomenon represents a challenge for risk assessment that could benefit from the use of biomarkers in the clinical development of new drug candidates. Flow cytometry, coupled with the lipophilic fluoroprobe Nile red, was correlated to histopathology, electron microscopy and inorganic phosphorus detection to validate the utility of this method for monitoring phospholipidosis in peripheral blood leukocytes. Replicate studies with model test compounds were conducted in which F344 rats were given 4 or 7 doses of either maprotiline hydrochloride, imipramine hydrochloride, tilorone dihydrochloride, amikacin hydrate or vehicle control. Transmission electron and light microscopy were used to examine peripheral blood smears and tissue samples for the presence of cytoplasmic vacuoles. Unstained and Nile red stained lysed peripheral blood samples were acquired for analysis using a FACScan flow cytometer. Inorganic phosphorus concentration in the liver was determined from extracted phospholipids and compared with flow cytometry and histological data. It was demonstrated that flow cytometric analysis of Nile red stained lysed whole blood can be used to detect drug-induced phospholipid accumulation in circulating peripheral leukocytes. Furthermore, clinically detectable leukocyte phospholipidosis may be a useful surrogate for coincident or premonitory detection of target organ phospholipidosis.

Validation of an in vitro screen for phospholipidosis using a high-content biology platform

Several cationic amphiphilic drugs cause local or systemic phospholipidosis (PLD) after chronic exposure in preclinical species. PLD is characterized by the accumulation of drug, phospholipid, and concentric lamellar bodies in cellular lysosomes. We have developed a fluorescence-based in vitro screen that is predictive of PLD using the Cellomics ArrayScan high-content screening platform, which captures and analyzes images from 96-well cell culture microtiter plates using multichannel fluorescence microscopy. I-13.35 adherent mouse spleen macrophage cells were cultured with drug and a fluorescently tagged phospholipid, N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (NBD-PE). Drug concentrations were used in a range from 1 to 100 micro mol/L. After 24 h incubations, the cells were fixed with formalin. NBD-PE uptake was quantified in controls and treated cells. Nuclei were identified by Hoechst 33258 staining and dead cells were identified using ethidium homodimer-2 incorporation. Thus, confounding accumulation of NBD-PE due to cytotoxicity that produces false-positive results at high concentrations was eliminated from quantitation by ethidium staining and employing cell gating (dead cell rejection). The assay was found to be both sensitive and selective in that 26 of 28 positive, phospholipidogenic controls and 8 of 8 negative, non-phospholipidogenic controls were correctly called.

Inhaled cationic amphiphilic drug-induced pulmonary phospholipidosis in rats and dogs: time-course and dose–response of biomarkers of exposure and effect

This study compares the pulmonary response to an inhaled highly soluble hydrochloride (CAD-HCl) with a low soluble sulphate salt (CAD-SO4) of a dicationic amphiphilic drug (CAD). These salts are known to accumulate in the lung. The bioavailability through gastrointestinal uptake is poor. Wistar rats and beagle dogs received repeated 1 h/day inhalation exposures over 1-4 weeks. The focus of this analysis is to appraise the correlation of markers of effects related to pulmonary phospholipidosis and cytotoxicity relative to the concentration of CAD in the lung tissue, alveolar macrophages and serum. Rats and dogs are known to experience remarkable differences in their respiratory minute volumes and respiratory patterns. In order to facilitate dosimetric comparisons, identical exposure paradigms and methodological procedures were selected. Over a wide range of cumulative dosages, the CADs bound to lung tissue and cells in bronchoalveolar lavage (BAL) paralleled, whilst no clear association existed in terms of plasma concentrations. This suggests that analysis of the fractional loading of BAL-cells (mainly alveolar macrophages) with CAD or CAD-surfactant complexes is amenable to monitor the accumulation of CADs in the lung. In terms of the comparative phospholipidosis-inducing potency, the CAD-HCl was more potent as compared to CAD-SO4. Following dosimetric adjustments, rats and dogs appeared to be equally susceptible to phospholipidosis. In summary, when exposed to equivalent concentrations of CADs, dogs did not demonstrate a markedly different susceptibility than rats. With regard to the relative intensity of changes, the increase of phospholipids in BAL-fluid and especially BAL-cells correlated with the cumulative exposure dose. Thus, with regard to probing the extent of CAD-induced 'overloading' of alveolar macrophages pharmacokinetic determinations in BAL-cells are considered superior to determinations in plasma. Additional advantages of using the alveolar macrophage as denominator to normalize pulmonary drug concentrations include comparisons across species, and exposure regimens are feasible based on almost readily available endpoints in both pre-clinical and selected clinical studies.

A comparative study of cytoplasmic granules imaged by the real-time microscope, Nile Red and Filipin in fibroblasts from patients with lipid storage diseases

Cytoplasmic granules in fibroblasts, visualized without stains, or labelled with Nile red, Filipin, or anti-LAMP-1 (lysosome-associated membrane protein 1), were imaged using the real-time microscope (RTM). New advances in light microscope technology were applied to detect cytoplasmic granules (RTM-visible granules) and characterize them by imaging contrast, size, shape, cellular distribution, composition, motion dynamics and quantity. Appearing as solid spheroids or ring structures, the majority of the RTM-visible granules contained Nile-red labelled neutral lipids. A smaller subpopulation, appearing dimmer, with less imaging contrast, contained Filipin-labelled free cholesterol. Most lipid storage granules have a diameter ranging from 0.3 mum to 0.6 mum, with a small population measuring up to 1 mum. They typically clustered in the perinuclear region and displayed relatively small oscillatory motion. Immunofluorescence based on LAMP-1 labelling highlighted granular structures that were distinct and separate from RTM-visible granules and other structures in the light modality of the microscope. RTM-visible granules were associated with disease phenotypes that have increased cellular neutral lipid stores corresponding to the Nile red-labelled droplets (e.g. triacylglycerides, cholesterol esters). As predicted, the fibroblast strains with a defect resulting in Wolman disease, when compared to control samples, consistently had RTM-visible granules, higher in imaging contrast and with larger diameters, that were labelled with Nile red, and also an increased frequency of Filipin-cholesterol complexes. By comparison, in fibroblasts where the lipid storage is less evident (Gaucher and Farber diseases) or from GM(1) gangliosidosis, where the primary storage substances are oligosaccharides, fewer and smaller RTM-visible granules were observed. In some cases, changes in contrast and morphology in the unstained cytoplasmic compartments were more evident than in the labelled structures. In summary, applying the RTM imaging system to fibroblasts enables differences between the various disease types to be seen and, in specific examples, a unique phenotype can be readily discerned.

Use of physicochemical calculation of pKa and CLogP to predict phospholipidosis-inducing potential: a case study with structurally related piperazines

Several cationic amphiphilic compounds are known to induce phospholipidosis, a condition primarily characterized by excessive accumulation of phospholipids in different cell types, giving the affected cells a finely foamy appearance. Excessive storage of lamellar membranous intralysosomal inclusion bodies is the hallmark for phospholipidosis on the electron microscopic level. In case of alveolar phospholipidosis, foamy macrophages accumulate within the alveolar spaces of the lung. Based on such findings in a one-year toxicity study with gepirone in rats, we studied the molecular properties of this compound and compounds suspected of being phospholipidosis inducers by means of physicochemical calculations. Physicochemical molecular calculations of molecular weight, ClogP (partition coefficient octanol/water), logD at pH 7.4, and pKa were performed, for the cationic amphiphilic compounds chlorpromazine, amiodarone, imipramine, propranolol and fluoxetine, and for the structurally related compounds 1-phenylpiperazine (1-PHP), gepirone (and its major metabolites, 3-OH-gepirone and 1-pyrimidinylpiperazine [1-PP]), and buspirone. ClogP and calculated pKa cluster differently for the amphiphilic drugs compared to the chemical series of piperazines. In line with this analysis, lamellar inclusion bodies were found in an in vitro validation experiment in the human monoblastoid cell line U-937, incubated for 96 h at 10 microg/mL with cationic amphiphilic drugs (amiodarone, imipramine, or propranolol). No such lamellar inclusion bodies were seen for any of the compounds from the chemical series of piperazines including gepirone and its metabolites. The data presented support the use of simple physicochemical calculations of ClogP and pKa to discriminate rapidly between compounds suspected of being phospholipidosis inducers. Finally, the discriminative power of these physicochemical ClogP and pKa calculations to predict phospholipidosis-inducing potential was further validated by extension of the set of compounds.

A toxicogenomic approach to drug-induced phospholipidosis: analysis of its induction mechanism and establishment of a novel in vitro screening system

Phospholipidosis is a lipid storage disorder in which excess phospholipids accumulate within cells. Some cationic amphiphilic compounds are known to have the potential to induce phospholipidosis. This study was undertaken to examine the molecular mechanisms that contribute to the development of phospholipidosis and to identify specific markers that might form the basis of an in vitro screening test. Specifically, we performed a large-scale gene expression analysis using DNA microarrays on human hepatoma HepG2 cells after they were treated with each of 12 compounds known to induce phospholipidosis. In electron microscopy, HepG2 cells developed lamellar myelin-like bodies in their lysosomes, the characteristic change of phospholipidosis, after treatment with these compounds for 72 h. DNA microarray analysis performed 6 and 24 h after treatment showed alterations in gene expression reflecting the inhibition of lysosomal phospholipase activity and lysosomal enzyme transport, and the induction of phospholipid and cholesterol biosynthesis. Seventeen genes that showed a similar expression profile following treatment were selected as candidate markers. Real-time PCR analysis confirmed that 12 gene markers showed significant concordance with lamellar myelin-like body formation. Furthermore, the average fold change values of these markers correlated well with the magnitude of this pathological change. In conclusion, microarray analysis revealed that factors such as alterations in lysosomal function and cholesterol metabolism were involved in the induction of phospholipidosis. Furthermore, comprehensive gene expression analysis enabled us to identify biomarkers of this condition that we then used to develop a rapid and sensitive in vitro screening test for drug-induced phospholipidosis.

Fluorescein angiographic monitoring of corneal vascularization in lipid keratopathy

The use of digital fluorescein corneal angiography to assist argon laser photocoagulation is reported. Photocoagulation was performed on the vascular supply of lipid keratopathy in the left eye of a 44-year-old woman.

Plasma lipids, lipoprotein composition and profile during induction and treatment of hepatic lipidosis in cats and the metabolic effect of one daily meal in healthy cats

Anorexia in obese cats may result in feline hepatic lipidosis (FHL). This study was designed to determine plasma lipids and lipoprotein profiles in queens at different stages during experimental induction of FHL (lean, obese, FHL), and after 10 weeks of treatment. Results were compared with those obtained from lean queens of same age fed the same diet but at a maintenance level, once a day. Hepatic lipidosis led to an increase in plasma triacylglycerol (TG), very low density lipoprotein (VLDL) and low density lipoprotein (LDL), and an enrichment of LDL with TG and of high density lipoprotein (HDL) with cholesterol, suggesting that VLDL secretion is enhanced, VLDL and LDL catabolism is lowered, and lipoprotein exchanges are impaired in FHL. This study also showed that cholesterolaemia is increased in cats fed at a dietary rhythm of one meal per day compared to ad libitum feeding.

[Degenerative neurological diseases of the central nervous system related to genetic neurolipidoses]

Genetic neurometabolic diseases in childhood are multisystemic. Surprisingly, these genetic diseases can manifest for the first time during adolescence and adulthood. In this case, the clinical presentation and evolutivity are very different. In childhood, many neurological systems are touched and their evolution is rapidly lethal. In the adult, their presentation may be that of a degenerative disease of the central nervous system and, according to the disease, the syndrome is very particular and very systematized. From our clinical and biological experience, we would like to suggest a decision tree.

Androgen biosynthesis from cholesterol to DHEA

Androgens and estrogens are made from dehydroepiandrosterone (DHEA), which is made from cholesterol via four steps. First, cholesterol enters the mitochondria with the assistance of the steroidogenic acute regulatory protein (StAR). Mutations in the StAR gene cause congenital lipoid adrenal hyperplasia. Second, within the mitochondria, cholesterol is converted to pregnenolone by the cholesterol side chain cleavage enzyme, P450scc. Third, pregnenolone undergoes 17alpha-hydroxylation by microsomal P450c17. Finally, 17-OH pregnenolone is converted to DHEA by the 17,20 lyase activity of P450c17. The ratio of the 17,20 lyase to 17alpha-hydroxylase activity of P450c17 determines the ratio of C21 to C19 steroids produced. This ratio is regulated post-translationally by at least three factors: the abundance of the electron-donating protein P450 oxidoreductase, the presence of cytochrome b(5), and the serine phosphorylation of P450c17. Study of these and related factors may yield important information about the pathophysiology of adrenarche and the polycystic ovary syndrome (PCOS).

Dietary L-carnitine supplementation in obese cats alters carnitine metabolism and decreases ketosis during fasting and induced hepatic lipidosis

This study was designed to determine whether dietary carnitine supplement could protect cats from ketosis and improve carnitine and lipid metabolism in experimental feline hepatic lipidosis (FHL). Lean spayed queens received a diet containing 40 (CL group, n = 7) or 1000 (CH group, n = 4) mg/kg of L-carnitine during obesity development. Plasma fatty acid, beta-hydroxybutyrate and carnitine, and liver and muscle carnitine concentrations were measured during experimental induction of FHL and after treatment. In control cats (CL group), fasting and FHL increased the plasma concentrations of fatty acids two- to threefold (P < 0.0001) and beta-hydroxybutyrate > 10-fold (from a basal 0.22 +/- 0.03 to 1.70 +/- 0.73 after 3 wk fasting and 3.13 +/- 0.49 mmol/L during FHL). In carnitine-supplemented cats, these variables increased significantly (P < 0.0001) only during FHL (beta-hydroxybutyrate, 1.42 +/- 0.17 mmol/L). L-Carnitine supplementation significantly increased plasma, muscle and liver carnitine concentrations. Liver carnitine concentration increased dramatically from the obese state to FHL in nonsupplemented cats, but not in supplemented cats, which suggests de novo synthesis of carnitine from endogenous amino acids in control cats and reversible storage in supplemented cats. These results demonstrate the protective effect of a dietary L-carnitine supplement against fasting ketosis during obesity induction. Increasing the L-carnitine level of diets in cats with low energy requirements, such as after neutering, and a high risk of obesity could therefore be recommended.

Antidepressant-induced lipidosis with special reference to tricyclic compounds

Cationic amphiphilic drugs, in general, induce phospholipid disturbances. Tricyclic, as well as other antidepressants belong to this group. In experimental animals, antidepressants induce lipid storage disorders in cells of most organs, a so-called generalized phospholipidosis. This disorder is conveniently detected by electron microscopic examination revealing myelin figures. Myelin figures or myeloid bodies are subcellular organelles containing unicentric lamellar layers. The lipidotic induction potency during in vivo is related to the apolarity of the compound. Metabolism of phospholipids takes place within the cell continuously. Several underlying mechanisms may be responsible for the induction of the phospholipid disturbance. For instance, it has been suggested that the compounds bind to phospholipids and such binding may alter the phospholipid's suitability as a substrate for phospholipases. Free TCA or metabolites thereof may also inhibit phospholipases directly, as has been demonstrated for sphingomyelinase in glioma and neuroblastoma cells. Both these mechanisms might result in phospholipidosis. Interaction between drug and phospholipid bilayer has been investigated by nuclear magnetic resonance technique. There seems to be large differences in the sensitivities amongst different organs. Steroid-producing cells of the adrenal cortex, testis and ovaries are in particular susceptible to drug-induced lipidosis. The so-called foam cells are lung macrophages located in the interstitium which become densely packed with myelin figures during TCA exposure. It requires about 3-6 weeks of treatment to develop this converted cell. In cell cultures however, phospholipidosis is demonstrated already after 24 h only. It appears that the cells that undergo TCA-induced lipidosis may recover after withdrawal of the drug. The time required to achieve complete recovery ranges from 3-4 weeks to several months, depending on the organ affected. Little is known about the functional significance of lipidosis. Even if TCA and other antidepressants show other effects, it has not been possible to exclusively relate it to phospholipidosis. However, few attempts have been made to correlate the physiological effects of TCAs in experimental animals to the morphological changes associated with phospholipidosis. There is an increasing evidence however, that cationic amphiphilic drugs may have effects on immune function, signal transduction and receptor-mediated events, effects that to some extent might be related to disturbances in phospholipid metabolism.

Matrix-assisted laser desorption ionization time-of-flight mass spectrometric analysis of glycosphingolipids including gangliosides

Long chain base compositions of gangliosides containing mainly stearic acid could be determined without any chemical modification by matrix-assisted laser desorption ionization time-of-flight mass spectrometry with delayed ion extraction (DE MALDI-TOF MS). The analytical results for the long chain base compositions of various samples of GM1 from the brain tissues of patients with different diseases at different ages confirmed that the proportion of d20:1 (icosasphingosine) and d20 (icosa-sphinganine) of the total sphingosine bases increased quickly until adolescent or adult age and then remained constant slightly exceeding 50%; this value was evidently higher than the proportion of d20:1 and d20 of GM1 in various adult mammalian brains. A long chain base composition of GM1 from the brain tissue of a patient with infantile type of GM1-gangliosidosis at 4y2m was abnormal and so was in two sibling patients with Spielmeyer-Vogt type of juvenile amaurotic idiocy at 19y and 21y in spite of that in the latter there was no accumulation of GM1 in the brain tissue. On the other hand, a patient with adult type of GM1 gangliosidosis at 66y showed a local accumulation of GM1 in the putamen and caudate nucleus, but its long chain base composition was found to be normal. It was of interest that the white matter of Eker rat with hereditary renal carcinoma contained a large amount of plasmalocerebroside as compared with the amount of cerebroside and sphingomyelin. The individual molecular species of plasmalocerebroside were identified by DE MALDI-TOF MS.

Betaine reduces hepatic lipidosis induced by carbon tetrachloride in Sprague-Dawley rats

Carbon tetrachloride-injected rats were given liquid diets with and without betaine for 7 d. Hepatic lipidosis was induced by 4 daily injections of carbon tetrachloride (CCl4). Animals were killed and their livers and blood taken for analysis of betaine, S-adenosylmethionine (SAM), betaine homocysteine methyltransferase (BHMT), triglyceride, alanine aminotransferase and aspartate aminotransferase. Liver samples were also processed and stained for histological examination. Supplemental betaine reduced triglyceride in the liver and centrilobular hepatic lipidosis induced by the CCl4 injections. In both the control and experimental groups receiving betaine, liver betaine, BHMT and SAM were significantly higher than in their respective groups not receiving betaine. This study provides evidence that betaine protects the liver against CCl4-induced lipidosis and may be a useful therapeutic and prophylactic agent in ameliorating the harmful effects of CCl4.

Protection against acetaminophen toxicity in CYP1A2 and CYP2E1 double-null mice

Acetaminophen (APAP) hepatotoxicity is due to its biotransformation to a reactive metabolite, N-acetyl-p-benzoquinone imine (NAPQI), that is capable of binding to cellular macromolecules. At least two forms of cytochrome P450, CYP2E1 and CYP1A2, have been implicated in this reaction in mice. To test the combined roles of CYP1A2 and CYP2E1 in an intact animal model, a double-null mouse line lacking functional expression of CYP1A2 and CYP2E1 was produced by cross-breeding Cyp1a2-/- mice with Cyp2e1-/- mice. Animals deficient in the expression of both P450s developed normally and exhibited no obvious phenotypic abnormalities. Comparison of the dose-response to APAP (200-1200 mg/kg) indicated that double-null animals were highly resistant to APAP-induced toxicity whereas the wild-type animals were sensitive. Administration of 600 to 800 mg/kg of this drug to male wild-type animals resulted in increased plasma concentrations of liver enzymes (alanine aminotransferase, sorbitol dehydrogenase), lipidosis, hepatic necrosis, and renal tubular necrosis. In contrast, when APAP of equivalent or higher dose was administered to the double-null mice, plasma levels of liver enzymes and liver histopathology were normal. However, administration of 1200 mg of APAP/kg to the double-null mice resulted in infrequent liver lipidosis and mild kidney lesions. Consistent with the protection from hepatotoxicity, the expected depletion of hepatic glutathione (GSH) content was significantly retarded and APAP covalent binding to hepatic cytosolic proteins was not detectable in the double-null mice. Likewise, in vitro activation of APAP by liver microsomes from the double-null mice was approximately one tenth of that in microsomes from wild-type mice. Thus, the protection against APAP toxicity afforded by deletion of both CYP2E1 and CYP1A2 likely reflects greatly diminished production of the toxic electrophile, NAPQI.

Four cholesterol-sensing proteins

What is the connection among the following three medical conditions: Niemann-Pick type C disease (a cause of mental retardation and early death), systemic lipidosis (in which an obscure side effect of numerous drugs transforms lysosomes into lamellar bodies), and holoprosencephaly (a catastrophe in embryonic development)? Recent evidence suggests that the pathogenesis in each use involves impaired sensing of cellular cholesterol.

Lipid composition of hepatic and adipose tissues from normal cats and from cats with idiopathic hepatic lipidosis

The purpose of this study was to characterize the lipid classes in hepatic and adipose tissues from cats with idiopathic hepatic lipidosis (IHL). Concentrations of triglyceride, phospholipid phosphorus, and free and total cholesterol were determined in lipid extracts of liver homogenates from 5 cats with IHL and 5 healthy control cats. Total fatty acid composition of liver and adipose tissue was also compared. Triglyceride accounted for 34% of liver by weight in cats with IHL (338 +/- 38 mg/g wet liver) versus 1% in control cats (9.9 +/- 1.0 mg/g wet liver, P < .001). The mass of cholesterol ester was significantly higher in triglyceride-free (TG-free) liver from cats with IHL (741 +/- 340 micrograms/g TG-free wet liver) compared to healthy cats (31 +/- 11 micrograms/g TG-free wet liver, P < .05). Total fatty acid composition of hepatic tissue in the 2 groups differed; palmitate was higher (19.5 +/- 1.1% of total fatty acids in cats with IHL versus 9.2 +/- 2.7% in controls, P < .05), stearate was lower (8.5 +/- 0.8% versus 16.8 +/- 1.1%, P < .05), oleate was higher (41.2 +/- 1.6% versus 31.1 +/- 1.8%, P < .05), and arachidonate was lower (1.2 +/- 0.2% versus 6.0 +/- 0.9%, P < .05). The total fatty acid composition of adipose tissue also differed between the 2 groups; palmitate was higher (26.2 +/- 1.2% in cats with IHL versus 21.3 +/- 0.6% in controls, P < .05), total monounsaturated fatty acids were higher (48.4 +/- 1.0% versus 45.0 +/- 0.8%, P < .05), linolenate was lower (13.3 +/- 1.6% versus 17.5 +/- 0.9%, P < .05), total (n-6) fatty acids were lower (13.8 +/- 1.38% versus 18.4 +/- 0.83%, P < .05), linolenate was lower (0.2 +/- 0.04% versus 0.7 +/- 0.06%, P < .06), and total (n-3) fatty acids were lower (0.3 +/- 0.02% versus 1.3 +/- 0.32%, P < .05). The fatty acid composition of both liver and adipose tissue was similar for stearate, oleate, linoleate, and linolenate in cats with IHL. These results support the hypothesis that the origin of hepatic triglyceride in cats with IHL is the mobilization of fatty acids from adipose tissue.

Nutrition and liver disease

Nutritional support is a key factor in the treatment of cats with hepatic disease. This is the only effective treatment in cats with hepatic lipidosis. The ideal diet would be one that fulfills all the basic energy and nutrient requirements of the patient, allows positive energy balance, provides all the nutrients necessary for liver regeneration, and prevents or aids the recovery from major complications of liver disease. Formulation of diets for cats with hepatobiliary diseases must also take into account their metabolic peculiarities. Anorexia is a common complication of liver disease and clinicians must take the necessary actions to ensure adequate energy and nutrient intake. No single diet will accommodate all patients and nutritional support must be adapted to each individual case based on the type of liver disease, extent of hepatic dysfunction, tolerance to dietary protein, and nutritional status.