Endotoxin rapidly induces changes in lipid metabolism that produce hypertriglyceridemia: low doses stimulate hepatic triglyceride production while high doses inhibit clearance

Role of HDL in cholesteryl ester metabolism of lipopolysaccharide-activated P388D1 macrophages

Infections share with atherosclerosis similar lipid alterations, with accumulation of cholesteryl esters (CEs) in activated macrophages and concomitant decrease of cholesterol-HDL (C-HDL). Yet the precise role of HDL during microbial infection has not been fully elucidated. Activation of P388D1 by lipopolysaccharide (LPS) triggered an increase of CEs and neutral lipid contents, along with a remarkable enhancement in 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate-HDL uptake. Similar results were found in human monocyte-derived macrophages and monocytes cocultured with phytohemagglutinin-activated lymphocytes. Inhibition of cholesterol esterification with Sandoz-58035 resulted in 80% suppression of CE biosynthesis in P388D1. However, only a 35% decrease of CE content, together with increased scavenger receptor class B member 1 (SR-B1) protein expression, was found after 72 h and thereafter up to 16 passages of continuous ACAT suppression. Chronic inhibition blunted the effect of LPS treatment on cholesterol metabolism, increased the ratio of free cholesterol/CE content and enhanced interleukin 6 secretion. These results imply that, besides de novo biosynthesis and acquisition by LDL, HDL contributes probably through SR-B1 to the increased CE content in macrophages, partly explaining the low levels of C-HDL during their activation. Our data suggest that in those conditions where more CEs are required, HDL rather than removing, may supply CEs to the cells.

Alteration of plasma phospholipid fatty acid profile in patients with septic shock

In septic shock patients, alterations of plasma phospholipid fatty acid profile have never been described. The purpose of this monocentric, non-interventional, observational prospective study was to describe this fatty acid profile in the early phase of septic shock in intensive care unit. Thirty-seven adult patients with septic shock were included after the first day of stay in intensive care unit, before any form of artificial nutritional support. Plasma phospholipid fatty acid composition was determined by gas chromatography. All biological data from patients with septic shock were compared with laboratory reference values. Patients presented hypocholesterolemia and hypertriglyceridemia. They had low concentrations of phospholipid fatty acids specifically n-6 and n-3 polyunsaturated fatty acids (PUFAs) with a high n-6/n-3 ratio. Plasma phospholipid PUFA concentrations were strongly correlated with cholesterolemia. PUFAs/SFAs (saturated fatty acids) and PUFAs/MUFAs (monounsaturated fatty acids) ratios were low because of low percentage of n-6 and n-3 PUFAs and high percentage of SFAs and MUFAs. Low levels of plasma long chain PUFAs (≥20 carbons) were significantly associated with mortality at 28th day. In conclusion, plasma phospholipid FA profile of septic patients is very characteristic, close to that of acute respiratory distress syndrome and mortality is associated with long chain PUFA decrease. This profile could be explained by numerous non-exclusive physio-pathological processes 1) an activation of hepatic de novo lipogenesis that could contribute to hepatic steatosis, 2) an elevated adipose tissue lipolysis, 3) an increased free radical attack of FA by oxidative stress, 4) an over-production of inflammatory lipid mediators.

Reciprocal interference of experimental dyslipidemia and food allergy in the evolution of both diseases

Background. Food allergies have been shown to reduce serum triacylglycerol, glucose, cholesterol, and free fatty acid levels in mice. In turn, dyslipidemias, especially dyslipidemias presenting with low levels of HDL cholesterol, are important risk factors for the development of atherosclerosis. However, the consequences of food allergies on dyslipidemia and atherosclerosis have not been fully investigated. Methods. Food allergy was induced using an egg white solution (EWS) in ovalbumin- (OVA-) sensitized C57BL/6 and low-density lipoprotein receptor knockout mice (LDLr^−/−) for 5 weeks and was confirmed by the high production of anti-OVA IgE and IgG1 antibodies in both mouse strains. Results. The allergic C57BL/6 mice exhibited EWS aversion that was associated with less visceral fat and high levels of anti-Ova IgE antibodies after 5 weeks of EWS intake compared to controls. However, LDLr^−/− allergic mice showed reduced anti-Ova IgE levels that were similar to the nonsensitized group. The LDLr^−/− allergic mice also demonstrated a reversal of food aversion and sustained visceral fat after 5 weeks of allergy. Although HDL cholesterol levels were reduced in both sensitized mouse strains, lipid deposition in thoracic and abdominal aorta as well as area and composition of atherosclerotic plaques as unaffected by chronic ingestion of EWS. Conclusion. LDLr^−/− mice develop an attenuated food allergy, as they showed a reversal of food aversion and lower IgE production after 5 weeks of induced allergy. The development of atherosclerosis, in turn, was not accelerated in the allergic LDLr^−/− group despite the more atherogenic lipid profile.

Increasing whole grain intake as part of prevention and treatment of nonalcoholic Fatty liver disease

In conjunction with the rise in rates of obesity, there has been an increase in the rate of nonalcoholic fatty liver disease (NAFLD). While NAFLD at least partially originates from poor diet, there is a lack of nutritional recommendations for patients with suspected or confirmed diagnosis of NAFLD, beyond eating a healthy diet, increasing physical activity, and emphasising weight loss. The limited current literature suggests that there may be opportunities to provide more tailored dietary advice for people diagnosed with or at risk of NAFLD. Epidemiological studies consistently find associations between whole grain intake and a reduced risk of obesity and related diseases, yet no work has been done on the potential of whole grains to prevent and/or be a part of the treatment for fatty liver diseases. In this review, we examine the potential and the current evidence for whole grains having an impact on NAFLD. Due to their nutrient and phytochemical composition, switching from consuming mainly refined grains to whole grains should be considered as part of the nutritional guidelines for patients diagnosed with or at risk for fatty liver disease.

Caspase-1 deficiency in mice reduces intestinal triglyceride absorption and hepatic triglyceride secretion

Caspase-1 is known to activate the proinflammatory cytokines IL-1β and IL-18. Additionally, it can cleave other substrates, including proteins involved in metabolism. Recently, we showed that caspase-1 deficiency in mice strongly reduces high-fat diet-induced weight gain, at least partly caused by an increased energy production. Increased feces secretion by caspase-1-deficient mice suggests that lipid malabsorption possibly further reduces adipose tissue mass. In this study we investigated whether caspase-1 plays a role in triglyceride-(TG)-rich lipoprotein metabolism using caspase-1-deficient and wild-type mice. Caspase-1 deficiency reduced the postprandial TG response to an oral lipid load, whereas TG-derived fatty acid (FA) uptake by peripheral tissues was not affected, demonstrated by unaltered kinetics of [(3)H]TG-labeled very low-density lipoprotein (VLDL)-like emulsion particles. An oral gavage of [(3)H]TG-containing olive oil revealed that caspase-1 deficiency reduced TG absorption and subsequent uptake of TG-derived FA in liver, muscle, and adipose tissue. Similarly, despite an elevated hepatic TG content, caspase-1 deficiency reduced hepatic VLDL-TG production. Intestinal and hepatic gene expression analysis revealed that caspase-1 deficiency did not affect FA oxidation or FA uptake but rather reduced intracellular FA transport, thereby limiting lipid availability for the assembly and secretion of TG-rich lipoproteins. The current study reveals a novel function for caspase-1, or caspase-1-cleaved substrates, in controlling intestinal TG absorption and hepatic TG secretion.

Growth and Development Symposium: Impacts of inflammation on cattle growth and carcass merit

Inflammation caused by bovine respiratory disease (BRD) continues to be one of the greatest challenges facing beef cattle producers and feedlot managers. Inflammation decreases DMI, ADG, and G:F in feedlot calves, decreasing growth rate and increasing days on feed, which results in economic losses during the feeding period. During the past decade, marketing of feedlot animals has changed from selling cattle on a live basis to a grid-based marketing system. When cattle are marketed on a live basis, the economic effects of BRD stop at increased health cost and decreased feedlot performance, carcass weight, and death loss. However, when cattle are marketed in a grid-based system, inflammation has the potential to also affect carcass cutability and quality. The effects of inflammation on feedlot cattle in regards to performance are well understood; however, specific effects on cattle growth and ultimately carcass merit are not as well described. Recent studies in feedlot cattle have indicated that the incidence of BRD decreases both HCW and marbling; however, mechanisms are not understood. Research in other species has demonstrated that during the acute phase response, pro-inflammatory cytokines promote skeletal muscle catabolism to supply AA and energy substrates for immune tissues. Further, during this early immune response, the liver changes its metabolic priorities to the production of acute phase proteins for use in host defense. Together these dramatic shifts in systemic metabolism may explain the detrimental effects on performance and carcass traits commonly associated with BRD in feedlot calves. Moreover, recent studies relative to human health have revealed complex multilevel interactions between the metabolic and immune systems, and highlighted inflammation as being a significant contributor to major metabolic diseases. The objective of this paper is to review data to help explain the economical and physiological effects of inflammation on cattle growth and carcass merit.

Nitric oxide, can it be only good? Increasing the antioxidant properties of nitric oxide in hepatocytes by YC-1 compound

The aim of the study was to evaluate the effect of Nitric oxide (NO) on redox changes and fat accumulation in hepatocytes. AML-12 hepatocytes were exposed to the NO donor Diethylenetriamine-NONOate (DETA-NO). DETA-NO led to a dose- and time-dependent increase in lipid accumulation in the cells, measured by Nile red fluorescence. Exposure of the cells to 1mM DETA-NO for 24h increased reactive oxygen species production, mainly peroxides. At the same time, NO induced elevation of reduced glutathione (GSH) and a mild activation of the antioxidant transcription factors Hypoxia-inducible factor 1α (HIF1α) and NF-E2 related factor 2 (Nrf-2). We used 100 μM YC-1 to inhibit HIF1α activity and induce activation of soluble Guanylate Cyclase (sGC). YC-1 alone did not affect fat accumulation, and only moderately increased the expression of Nrf-2-targeted genes Heme oxygenase 1 (Hmox1), NAD(P)H dehydrogenase (quinone 1) (Nqo1) and Glutathione S-transferase α1 (Gstα1). However, YC-1 abolished the negative effect of NO on fat accumulation when administered together. Strikingly, YC-1 potentiated the effect of NO on Nrf-2 activation, thus increasing dramatically the antioxidant properties of NO. Moreover, YC-1 intensified the effect of NO on the expression of peroxisome-proliferator-activated receptor-gamma co-activator 1α (PGC1α) and mitochondrial biogenesis markers. This study suggests that YC-1 may shift the deleterious effects of NO into the beneficial ones, and may improve the antioxidant properties of NO.

Effects of statins on liver cell function and inflammation in septic rats

BACKGROUND

Several studies suggest that the presence of statins may be beneficial during sepsis, but this idea is controversial. The aim of this study was to investigate the effects of long-term statin treatment in the livers of septic animals, focusing on its antioxidant, antiinflammatory, and metabolic properties.

MATERIALS AND METHODS

Male Wistar rats were treated orally with simvastatin, atorvastatin, or vehicle once a d. After 30 d, sepsis was induced by cecal ligation and puncture (CLP) in Control, Simvastatin-treated, and Atorvastatin-treated groups, while the Sham group underwent only laparotomy. The Basal Simvastatin and Basal Atorvastatin groups received only their respective drugs without surgery. Twenty-four h after CLP or laparotomy, samples were collected from anesthetized rats for evaluation of hepatic oxidative stress, liver histology, hepatic mitochondria enzyme activity, leukocyte counts in blood and peritoneal cavity, gene expression of hepatic superoxide dismutase and TNF-2, and plasma biochemistry.

RESULTS

Most parameters that we tested exhibited expected changes upon sepsis induction. However, statin treatment only improved liver mitochondrial enzymatic activity. In other parameters, simvastatin and atorvastatin failed to protect the liver against injuries incurred upon the CLP-induced polymicrobial sepsis model.

CONCLUSIONS

Pretreatment with simvastatin or atorvastatin alone before sepsis induction improved mitochondrial activity in the liver; however, this result was not reproduced in other biomarkers of liver function and leukocyte migration during sepsis. Future studies should be performed to evaluate whether statins can be combined with other drugs to increase the efficacy of sepsis therapy.

Targeted metabolomics for discrimination of systemic inflammatory disorders in critically ill patients

The occurrence of systemic inflammatory response syndrome (SIRS) remains a major problem in intensive care units with high morbidity and mortality. The differentiation between noninfectious and infectious etiologies of this disorder is challenging in routine clinical practice. Many biomarkers have been suggested for this purpose; however, sensitivity and specificity even of high-ranking biomarkers remain insufficient. Recently, metabolic profiling has attracted interest for biomarker discovery. The objective of this study was to identify metabolic biomarkers for differentiation of SIRS/sepsis. A total of 186 meta-bolites comprising six analyte classes were determined in 143 patients (74 SIRS, 69 sepsis) by LC-MS/MS. Two markers (C10:1 and PCaaC32:0) revealed significantly higher concentrations in sepsis. A classification model comprising these markers resulted in 80% and 70% correct classifications in a training set and a test set, respectively.This study demonstrates that acylcarnitines and glycerophosphatidylcholines may be helpful for differentiation of infectious from noninfectious systemic inflammation due to their significantly higher concentration in sepsis patients. Considering the well known pathophysiological relevance of lipid induction by bacterial components, metabolites as identified in this study are promising biomarker candidates in the differential diagnosis of SIRS and sepsis.

Inflammation and lipid signaling in the etiology of insulin resistance

Inflammation and lipid signaling are intertwined modulators of homeostasis and immunity. In addition to the extensively studied eicosanoids and inositol phospholipids, emerging studies indicate that many other lipid species act to positively and negatively regulate inflammatory responses. Conversely, inflammatory signaling can significantly alter lipid metabolism in the liver, adipose tissue, skeletal muscle, and macrophage in the context of infection, diabetes, and atherosclerosis. Here, we review recent findings related to this interconnected network from the perspective of immunity and metabolic disease.

Nutritional repletion of children with severe acute malnutrition does not affect VLDL apolipoprotein B-100 synthesis rate

VLDL apo B-100 is essential for the secretion of liver fat. It is thought that synthesis of this lipoprotein is impaired in childhood severe acute malnutrition (SAM), especially in the edematous syndromes, and that this contributes to the common occurrence of hepatic steatosis in this condition. However, to our knowledge, it has not been confirmed that VLDL apo B-100 synthesis is slower in edematous compared with nonedematous SAM and that it is impaired in the malnourished compared with the well-nourished state. Therefore, VLDL apo B-100 kinetics were measured in 2 groups of children with SAM (15 edematous and 7 nonedematous), aged 4-20 mo, at 3 stages during treatment. Measurements were done at 4 ± 1 d postadmission, mid- catch-up growth in weight, and at recovery (normal weight-for-length). VLDL apo B-100 synthesis was determined using stable isotope methodology to measure the rate of incorporation of (2)H(3)-leucine into its apoprotein moiety. The fractional and absolute synthesis of VLDL apo B-100 did not differ between the groups or from the initial malnourished stage to the recovery stage. Concentrations of VLDL apo B-100 were greater in the edematous than in the nonedematous group (P < 0.04) and did not differ from the initial stage to recovery. The data indicate that VLDL apo B-100 synthesis is not reduced when children develop either edematous or nonedematous SAM.

Cell walls of Saccharomyces cerevisiae differentially modulated innate immunity and glucose metabolism during late systemic inflammation

Background

Salmonella causes acute systemic inflammation by using its virulence factors to invade the intestinal epithelium. But, prolonged inflammation may provoke severe body catabolism and immunological diseases. Salmonella has become more life-threatening due to emergence of multiple-antibiotic resistant strains. Mannose-rich oligosaccharides (MOS) from cells walls of Saccharomyces cerevisiae have shown to bind mannose-specific lectin of Gram-negative bacteria including Salmonella, and prevent their adherence to intestinal epithelial cells. However, whether MOS may potentially mitigate systemic inflammation is not investigated yet. Moreover, molecular events underlying innate immune responses and metabolic activities during late inflammation, in presence or absence of MOS, are unknown.

Methods and Principal Findings

Using a Salmonella LPS-induced systemic inflammation chicken model and microarray analysis, we investigated the effects of MOS and virginiamycin (VIRG, a sub-therapeutic antibiotic) on innate immunity and glucose metabolism during late inflammation. Here, we demonstrate that MOS and VIRG modulated innate immunity and metabolic genes differently. Innate immune responses were principally mediated by intestinal IL-3, but not TNF-α, IL-1 or IL-6, whereas glucose mobilization occurred through intestinal gluconeogenesis only. MOS inherently induced IL-3 expression in control hosts. Consequent to LPS challenge, IL-3 induction in VIRG hosts but not differentially expressed in MOS hosts revealed that MOS counteracted LPS's detrimental inflammatory effects. Metabolic pathways are built to elucidate the mechanisms by which VIRG host's higher energy requirements were met: including gene up-regulations for intestinal gluconeogenesis (PEPCK) and liver glycolysis (ENO2), and intriguingly liver fatty acid synthesis through ATP citrate synthase (CS) down-regulation and ATP citrate lyase (ACLY) and malic enzyme (ME) up-regulations. However, MOS host's lower energy demands were sufficiently met through TCA citrate-derived energy, as indicated by CS up-regulation.

Conclusions

MOS terminated inflammation earlier than VIRG and reduced glucose mobilization, thus representing a novel biological strategy to alleviate Salmonella-induced systemic inflammation in human and animal hosts.

Is the gut microbiota a new factor contributing to obesity and its metabolic disorders?

The gut microbiota refers to the trillions of microorganisms residing in the intestine and is integral in multiple physiological processes of the host. Recent research has shown that gut bacteria play a role in metabolic disorders such as obesity, diabetes, and cardiovascular diseases. The mechanisms by which the gut microbiota affects metabolic diseases are by two major routes: (1) the innate immune response to the structural components of bacteria (e.g., lipopolysaccharide) resulting in inflammation and (2) bacterial metabolites of dietary compounds (e.g., SCFA from fiber), which have biological activities that regulate host functions. Gut microbiota has evolved with humans as a mutualistic partner, but dysbiosis in a form of altered gut metagenome and collected microbial activities, in combination with classic genetic and environmental factors, may promote the development of metabolic disorders. This paper reviews the available literature about the gut microbiota and aforementioned metabolic disorders and reveals the gaps in knowledge for future study.

Aspirin reduces hypertriglyceridemia by lowering VLDL-triglyceride production in mice fed a high-fat diet

Systemic inflammation is strongly involved in the pathophysiology of the metabolic syndrome, a cluster of metabolic risk factors that includes hypertriglyceridemia. Aspirin treatment lowers inflammation via inhibition of NF-κB activity but also reduces hypertriglyceridemia in humans. The aim of this study was to investigate the mechanism by which aspirin improves hypertriglyceridemia. Human apolipoprotein CI (apoCI)-expressing mice (APOC1 mice), an animal model with elevated plasma triglyceride (TG) levels, as well as normolipidemic wild-type (WT) mice were fed a high-fat diet (HFD) and treated with aspirin. Aspirin treatment reduced hepatic NF-κB activity in HFD-fed APOC1 and WT mice, and in addition, aspirin decreased plasma TG levels (-32%, P < 0.05) in hypertriglyceridemic APOC1 mice. This TG-lowering effect could not be explained by enhanced VLDL-TG clearance, but aspirin selectively reduced hepatic production of VLDL-TG in both APOC1 (-28%, P < 0.05) and WT mice (-33%, P < 0.05) without affecting VLDL-apoB production. Aspirin did not alter hepatic expression of genes involved in FA oxidation, lipogenesis, and VLDL production but decreased the incorporation of plasma-derived FA by the liver into VLDL-TG (-24%, P < 0.05), which was independent of hepatic expression of genes involved in FA uptake and transport. We conclude that aspirin improves hypertriglyceridemia by decreasing VLDL-TG production without affecting VLDL particle production. Therefore, the inhibition of inflammatory pathways by aspirin could be an interesting target for the treatment of hypertriglyceridemia.

Adipose-selective overexpression of ABHD5/CGI-58 does not increase lipolysis or protect against diet-induced obesity

Adipose triglyceride lipase (ATGL) catalyzes the first step of triacylglycerol hydrolysis in adipocytes. Abhydrolase domain 5 (ABHD5) increases ATGL activity by an unknown mechanism. Prior studies have suggested that the expression of ABHD5 is limiting for lipolysis in adipocytes, as addition of recombinant ABHD5 increases in vitro TAG hydrolase activity of adipocyte lysates. To test this hypothesis in vivo, we generated transgenic mice that express 6-fold higher ABHD5 in adipose tissue relative to wild-type (WT) mice. In vivo lipolysis increased to a similar extent in ABHD5 transgenic and WT mice following an overnight fast or injection of either a β-adrenergic receptor agonist or lipopolysaccharide. Similarly, basal and β-adrenergic-stimulated lipolysis was comparable in adipocytes isolated from ABHD5 transgenic and WT mice. Although ABHD5 expression was elevated in thioglycolate-elicited macrophages from ABHD5 transgenic mice, Toll-like receptor 4 (TLR4) signaling was comparable in macrophages isolated from ABHD5 transgenic and WT mice. Overexpression of ABHD5 did not prevent the development of obesity in mice fed a high-fat diet, as shown by comparison of body weight, body fat percentage, and adipocyte hypertrophy of ABHD5 transgenic to WT mice. The expression of ABHD5 in mouse adipose tissue is not limiting for either basal or stimulated lipolysis.

Fenofibrate, a PPAR{alpha} agonist, decreases atrogenes and myostatin expression and improves arthritis-induced skeletal muscle atrophy

Arthritis is a chronic inflammatory illness that induces cachexia, which has a direct impact on morbidity and mortality. Fenofibrate, a selective PPARα activator prescribed to treat human dyslipidemia, has been reported to decrease inflammation in rheumatoid arthritis patients. The aim of this study was to elucidate whether fenofibrate is able to ameliorate skeletal muscle wasting in adjuvant-induced arthritis, an experimental model of rheumatoid arthritis. On day 4 after adjuvant injection, control and arthritic rats were treated with 300 mg/kg fenofibrate until day 15, when all rats were euthanized. Fenofibrate decreased external signs of arthritis and liver TNFα and blocked arthritis-induced decreased in PPARα expression in the gastrocnemius muscle. Arthritis decreased gastrocnemius weight, which results from a decrease in cross-section area and myofiber size, whereas fenofibrate administration to arthritic rats attenuated the decrease in both gastrocnemius weight and fast myofiber size. Fenofibrate treatment prevented arthritis-induced increase in atrogin-1 and MuRF1 expression in the gastrocnemius. Neither arthritis nor fenofibrate administration modify Akt-FoxO3 signaling. Myostatin expression was not modified by arthritis, but fenofibrate decreased myostatin expression in the gastrocnemius of arthritic rats. Arthritis increased muscle expression of MyoD, PCNA, and myogenin in the rats treated with vehicle but not in those treated with fenofibrate. The results indicate that, in experimental arthritis, fenofibrate decreases skeletal muscle atrophy through inhibition of the ubiquitin-proteasome system and myostatin.

Inflammation inhibits the expression of phosphoenolpyruvate carboxykinase in liver and adipose tissue

Inhibition of adipocyte triglyceride biosynthesis is required for fatty acid mobilization during inflammation. Triglyceride biosynthesis requires glycerol 3-phosphate and phosphoenolpyruvate carboxykinase (PEPCK) plays a key role. We demonstrate that LPS, zymosan, and TNF-α decrease PEPCK in liver and fat. Turpentine decreases PEPCK in liver, but not in fat. The LPS-induced decrease in PEPCK does not occur in TLR4 deficient animals, indicating that this receptor is required. The LPS-induced decrease in hepatic PEPCK does not occur in TNF receptor/IL-1 receptor knockout mice, but occurs in fat, indicating that TNF-α/IL-1 is essential for the decrease in liver but not fat. In 3T3-L1 adipocytes TNF-α, IL-1, IL-6, and IFNγ inhibit PEPCK indicating that there are multiple pathways by which PEPCK is decreased in adipocytes. The binding of PPARγ and RXRα to the PPARγ response element in the PEPCK promoter is markedly decreased in adipose tissue nuclear extracts from LPS treated animals. Lipopolysaccharide and zymosan reduce PPARγ and RXRα expression in fat, suggesting that a decrease in PPARγ and RXRα accounts for the decrease in PEPCK. Thus, there are multiple cytokine pathways by which inflammation inhibits PEPCK expression in adipose tissue which could contribute to the increased mobilization of fatty acids during inflammation.

Protective effect of dietary tocotrienols against infection and inflammation-induced hyperlipidemia: an in vivo and in silico study

Currently used hypolipidemic drugs, Fluvastatin and Atorvastatin, act via inhibiting the rate-limiting enzyme 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase of the mevalonate pathway. The associated severe side-effects of these statins led us to explore the therapeutic potentials of naturally occurring Tocomin (mixture of dietary α-, β-, γ- and δ-tocotrienols). Tocomin (10 mg) was orally administered daily for 10 days before and 12 h after bacterial lipopolysaccharide (200 μg) or 24 h after zymosan (20 mg) or turpentine (0.5 mL) to Syrian hamsters. The data showed that Tocomin significantly reduced the levels of plasma and lipoprotein lipids, cholesterol, apoB, small dense (sd)-LDL as well as LDL in the hyperlipidemia-induced hamsters. Further, the mechanism of action of α-, β-, γ- and δ-tocotrienols was validated by docking studies with HMG-CoA reductase enzyme using the Molegro Virtual Docker. The inhibition of HMG-CoA reductase predicted in terms of MolDockScore and interaction energy suggest the comparative potential in the descending order: Atorvastatin > Fluvastatin ~ δ > γ > β > α. The results favor the daily intake of naturally occurring tocotrienols as dietary supplement in the prevention and treatment of infection/inflammation induced dyslipidemia compared with the hypolipidemic drugs.

Hepatocyte-specific IKK-β activation enhances VLDL-triglyceride production in APOE*3-Leiden mice

Low-grade inflammation in different tissues, including activation of the nuclear factor κB pathway in liver, is involved in metabolic disorders such as type 2 diabetes and cardiovascular diseases (CVDs). In this study, we investigated the relation between chronic hepatocyte-specific overexpression of IkB kinase (IKK)-β and hypertriglyceridemia, an important risk factor for CVD, by evaluating whether activation of IKK-β only in the hepatocyte affects VLDL-triglyceride (TG) metabolism directly. Transgenic overexpression of constitutively active human IKK-β specifically in hepatocytes of hyperlipidemic APOE*3-Leiden mice clearly induced hypertriglyceridemia. Mechanistic in vivo studies revealed that the hypertriglyceridemia was caused by increased hepatic VLDL-TG production rather than a change in plasma VLDL-TG clearance. Studies in primary hepatocytes showed that IKK-β overexpression also enhances TG secretion in vitro, indicating a direct relation between IKK-β activation and TG production within the hepatocyte. Hepatic lipid analysis and hepatic gene expression analysis of pathways involved in lipid metabolism suggested that hepatocyte-specific IKK-β overexpression increases VLDL production not by increased steatosis or decreased FA oxidation, but most likely by carbohydrate-responsive element binding protein-mediated upregulation of Fas expression. These findings implicate that specific activation of inflammatory pathways exclusively within hepatocytes induces hypertriglyceridemia. Furthermore, we identify the hepatocytic IKK-β pathway as a possible target to treat hypertriglyceridemia.

Endotoxin activates de novo sphingolipid biosynthesis via nuclear factor kappa B-mediated upregulation of Sptlc2

Sphingolipids are membrane components and are involved in cell proliferation, apoptosis and metabolic regulation. In this study we investigated whether de novo sphingolipid biosynthesis in macrophages is regulated by inflammatory stimuli. Lipopolysaccharide (LPS) treatment upregulated Sptlc2, a subunit of serine palmitoyltransferase (SPT), mRNA and protein in Raw264.7 and mouse peritoneal macrophages, but Sptlc1, another subunit of SPT, was not altered. SPT activation by LPS elevated cellular levels of ceramides and sphingomyelin (SM). Pharmacological inhibition of nuclear factor kappa B (NFκB) prevented LPS-induced upregulation of Sptlc2 while transfection of p65 subunit of NFκB upregulated Sptlc2 and increased cellular ceramide levels. In contrast, MAP kinases were not involved in regulation of sphingolipid biosynthesis. Analysis of Sptlc2 promoter and chromatin immunoprecipitation (ChIP) assay showed that NFκB binding sites are located in Sptlc2 promoter region. Our results demonstrate that inflammatory stimuli activate de novo sphingolipid biosynthesis via NFκB and may play a critical role in lipid metabolism in macrophages.

Endotoxin levels correlate positively with a sedentary lifestyle and negatively with highly trained subjects

Introduction

A sedentary lifestyle increases the risk of developing cardiovascular disease, obesity, and diabetes. This phenomenon is supported by recent studies suggesting a chronic, low-grade inflammation status. Endotoxin derived from gut flora may be key to the development of inflammation by stimulating the secretion of inflammatory factors. This study aimed to examine plasma inflammatory markers and endotoxin levels in individuals with a sedentary lifestyle and/or in highly trained subjects at rest. Methods: Fourteen male subjects (sedentary lifestyle n = 7; highly trained subjects n = 7) were recruited. Blood samples were collected after an overnight fast (~12 h). The plasmatic endotoxin, plasminogen activator inhibitor type-1 (PAI-1), monocyte chemotactic protein-1 (MCP1), ICAM/CD54, VCAM/CD106 and lipid profile levels were determined.

Results

Endotoxinemia was lower in the highly trained subject group relative to the sedentary subjects (p < 0.002). In addition, we observed a positive correlation between endotoxin and PAI-1 (r = 0.85, p < 0.0001), endotoxin and total cholesterol (r = 0.65; p < 0.01), endotoxin and LDL-c (r = 0.55; p < 0.049) and endotoxin and TG levels (r = 0.90; p < 0.0001). The plasma levels of MCP-1, ICAM/CD54 and VCAM/CD106 did not differ.

Conclusion

These results indicate that a lifestyle associated with high-intensity and high-volume exercise induces favorable changes in chronic low-grade inflammation markers and may reduce the risk for diseases such as obesity, diabetes and cardiovascular diseases.

Gene expression profiles characterize inflammation stages in the acute lung injury in mice

Acute Lung Injury (ALI) carries about 50 percent mortality and is frequently associated with an infection (sepsis). Life-support treatment with mechanical ventilation rescues many patients, although superimposed infection or multiple organ failure can result in death. The outcome of a patient developing sepsis depends on two factors: the infection and the pre-existing inflammation. In this study, we described each stage of the inflammation process using a transcriptional approach and an animal model. Female C57BL6/J mice received an intravenous oleic acid injection to induce an acute lung injury (ALI). Lung expression patterns were analyzed using a 9900 cDNA mouse microarray (MUSV29K). Our gene-expression analysis revealed marked changes in the immune and inflammatory response metabolic pathways, notably lipid metabolism and transcription. The early stage (1 hour–1.5 hours) is characterized by a pro-inflammatory immune response. Later (3 hours–4 hours), the immune cells migrate into inflamed tissues through interaction with vascular endothelial cells. Finally, at late stages of lung inflammation (18 hours–24 hours), metabolism is deeply disturbed. Highly expressed pro-inflammatory cytokines activate transcription of many genes and lipid metabolism. In this study, we described a global overview of critical events occurring during lung inflammation which is essential to understand infectious pathologies such as sepsis where inflammation and infection are intertwined. Based on these data, it becomes possible to isolate the impact of a pathogen at the transcriptional level from the global gene expression modifications resulting from the infection associated with the inflammation.

Nutritional and clinicopathological effects of post operative parenteral nutrition following small intestinal resection and anastomosis in the mature horse

REASONS FOR PERFORMING STUDY

There is an absence of data describing the nutritional requirements and nutritional status of horses following surgery for colic; furthermore, the potential effect of parenteral nutrition (PN) on improving nutritional status in such cases is unknown.

HYPOTHESIS

Post operative colic cases suffer from a potentially detrimental negative energy balance and the PN formulation developed in this study would lead to clinicopathologically detectable improvements in the subjects' nutritional status.

METHODS

Several clinicopathological variables, some known to be associated with nutritional status, were compared in 2 groups of horses in the post operative period following colic surgery; Group N (n = 15) were treated with PN and Group C (n = 15) were starved routinely.

RESULTS

Group N had significantly lower serum concentrations of triglycerides, total bilirubin, albumin and urea and significantly higher serum concentrations of glucose and insulin compared with Group C in the post operative period.

CONCLUSIONS

The control group of horses demonstrated significant clinicopathological evidence of starvation and the described PN protocol resulted in a demonstrably improved nutritional status in the treated horses.

POTENTIAL RELEVANCE

Further study is required to investigate clinical benefits and possible harmful side effects of post operative parenteral nutrition before the technique can be advocated for widespread use in practice.

Severe hypertriglyceridaemia in clinically ill horses: diagnosis, treatment and outcome

REASONS FOR PERFORMING STUDY

Sporadic measurement of serum triglycerides in depressed and inappetant clinically ill horses revealed severe hypertriglyceridaemia without visible evidence of lipaemia on several occasions, leading to the inclusion of serum triglyceride concentrations in the routine serum biochemistry evaluation of our hospital. Since then, more cases have been identified and treated for hypertriglyceridaemia, raising questions about the prevalence, predisposing factors and significance of these findings.

HYPOTHESES

1) Severe hypertriglyceridaemia without visible opacity of the serum occurs more commonly in clinically ill and inappetant horses than previously described and 2) appropriate treatment using i.v. dextrose and/or partial parenteral nutrition would decrease serum triglycerides to normal limits and might result in improved appetite and attitude of the patient.

METHODS

The laboratory computer database from 2000 and 2001 was searched for increased serum triglycerides (> 5.65 mmol/l) in any horse breed, ponies and miniature breeds excluded. Data analysed included subject details, diagnosis, clinical and laboratory parameters, treatment, response to treatment and outcome.

RESULTS

Severe hypertriglyceridaemia was identified in 13 horses, with serum triglyceride concentrations 6.17-18.29 mmol/l, while none showed visible lipaemia. All horses had clinical and laboratory findings consistent with systemic inflammatory response syndrome and all but one had an increased serum creatinine concentration. Treatment with i.v. dextrose and/or partial parenteral nutrition resulted in decrease of the serum triglycerides to normal limits.

CONCLUSIONS

Severe hypertriglyceridaemia occurs in inappetant and clinically ill horses without evidence of serum opacity more commonly than previously described. The presence of systemic inflammatory response syndrome might predispose horses to hypertriglyceridaemia, while the increased creatinine concentration might be a predisposing factor or result of the condition. Horses identified in our study readily responded to treatment and appetite and attitude improved coincident with decrease of the serum triglycerides to normal limits.

POTENTIAL RELEVANCE

Hypertriglyceridaemia could perpetuate inappetance and depression in clinically ill horses and potentially predispose to fatty infiltration of the liver and other organ systems.

Relationship between periodontitis and hepatic abnormalities in young adults

OBJECTIVE

Obesity has been implicated as a risk factor for periodontitis and non-alcoholic fatty liver disease (NAFLD). In NAFLD, elevated alanine aminotransferase (ALT) is associated with obesity. Although a possible interrelationship between liver function and periodontitis has been reported among the middle-aged population, the correlation in young adults is little known. This study was designed to investigate the relationship between ALT and the presence of periodontitis in university students in Japan.

MATERIAL AND METHODS

Medical and oral health data were collected in a cross-sectional examination conducted by the Health Service Center of Okayama University. Systemically healthy, non-smoking students aged 18 and 19 years old (n = 2225) were included. The protocol of the United States National Health and Nutrition Examination Survey was applied. Subjects with probing pocket depth >or= 4 mm were defined as having periodontitis. Logistic regression analysis was used to estimate the association between ALT, body mass index and periodontitis.

RESULTS

The number of subjects with periodontitis was 104 (4.7%). In males, having periodontitis was significantly associated with an increased level of ALT (>or= 41 IU/l) in logistic regression analysis (adjusted odds ratio 2.3; 95% confidence interval 1.0-5.2; p < 0.05). However, there was no significant association between periodontitis and ALT in female students.

CONCLUSIONS

Elevated ALT could be a potential risk indicator for periodontitis among young males. Monitoring hepatic abnormalities to prevent periodontitis must be better understood, even in the young adult population.

Choline or CDP-choline alters serum lipid responses to endotoxin in dogs and rats: involvement of the peripheral nicotinic acetylcholine receptors

We showed previously that choline administration protects dogs from endotoxin-induced multiple organ injury and platelet dysfunctions. Because sepsis/endotoxemia is associated with alterations in lipid metabolism, we have investigated whether choline or cytidine-5'-diphosphate choline, a choline donor, alters serum lipid responses to endotoxin in dogs and rats. In response to endotoxin, serum concentrations of triglycerides, choline-containing phospholipids, total cholesterol, and high-density lipoprotein cholesterol increased in a dose- and time-related manner. Administration of choline (20 mg/kg i.v. in dogs or 90 mg/kg i.p. in rats) or cytidine-5'-diphosphate choline (70 mg/kg i.v. in dogs) 5 min before and 4 and 8 h after endotoxin blocked or attenuated the increases in serum triglycerides, total cholesterol, and nonesterified fatty acids. Endotoxin-induced elevations in serum phospholipid levels did not change in rats and were enhanced in dogs by choline. In rats, serum lipid response to endotoxin was accompanied by severalfold elevations in serum levels of hepatorenal injury markers; their elevations were also blocked by choline. Pretreatment with hexamethonium blocked choline's effects on serum lipids and hepatorenal injury markers. Pretreatment with atropine blocked endotoxin-induced elevations in serum lipid and hepatorenal injury markers, but failed to alter choline's actions on these parameters. Choline treatment improved survival rate of rats in lethal endotoxin shock. In conclusion, these data show that choline treatment alters serum lipid responses to endotoxin and prevents hepatorenal injury during endotoxemia through a nicotinic acetylcholine receptor-mediated mechanism. Hence, choline and choline-containing compounds may have a therapeutic potential in the treatment of endotoxemia/sepsis.

Lipoprotein lipase is nitrated in vivo after lipopolysaccharide challenge

Lipopolysaccharide (LPS) administration down-regulates lipoprotein lipase (LPL) activity at the posttranscriptional level. Hypertriglyceridemia is the main metabolic consequence of this fall in LPL activity and is presumably involved in the innate immune response to infection. Nitric oxide (NO) has been implicated in LPS-induced down-regulation of LPL activity, but whether its effects are direct or indirect remains unclear. Here we examined the potential nitration of LPL in vivo in response to LPS challenge in rats. We found hypertriglyceridemia, iNOS expression, NO overproduction, and a generalized decrease in LPL activity in tissues 6 h after LPS administration. LPL sensitivity to nitration was first explored by in vitro exposure of bovine LPL to peroxynitrite, a reactive nitrogen species (RNS). Nitration was confirmed by anti-nitrotyrosine Western blot and subsequent identification of specific nitrotyrosine-containing LPL sequences by tandem mass spectrometry. Further analysis by targeted mass spectrometry revealed three in vivo-nitrated tyrosine residues in heart LPL from LPS-challenged rats. This is the first study to identify nitrated tyrosine residues in LPL, both in vitro and in vivo, and it demonstrates that LPL is a target for RNS in endotoxemia. These results indicate that LPL nitration may be a new mechanism of LPL activity regulation in vivo.

Effects of topical application of lipopolysaccharide and proteases on hepatic injury induced by high-cholesterol diet in rats

BACKGROUND AND OBJECTIVE

Topical application of lipopolysaccharide and proteases to the gingival sulcus induced not only periodontal inflammation but also detectable liver changes in rats fed a normal diet. However, these changes in the liver were not sufficient to induce pathological consequences. The purpose of the present study was to investigate whether gingival inflammation-induced liver change would have more dramatic pathological consequences in rats fed a high-cholesterol diet compared with the effect of the high-cholesterol diet alone.

MATERIAL AND METHODS

Twenty-four male Wistar rats were divided into four groups. During an 8 week experimental period, two groups were fed a normal diet and the other two were fed a high-cholesterol diet containing 1% cholesterol (w/w) and 0.5% cholic acid (w/w). Four weeks prior to the end of the experimental period, one of each of the dietary groups received daily topical application of lipopolysaccharide and proteases to the gingival sulcus, while the other was treated with pyrogen-free water.

RESULTS

In the rats without application of lipopolysaccharide and proteases, the serum level of hexanoyl-lysine, scores of steatosis and inflammation, and concentration of 8-hydroxydeoxyguanosine in liver of rats fed a high-cholesterol diet were higher than in those fed a normal diet. In rats fed a high-cholesterol diet, the scores of steatosis and inflammation and the concentration of 8-hydroxydeoxyguanosine in the liver of rats with application of lipopolysaccharide and proteases were higher than in those without.

CONCLUSION

In a rat model, application of lipopolysaccharide and proteases to the gingival sulcus augmented the effect of a high-cholesterol diet on steatosis, inflammation and oxidative damage in the liver.

Impairment of 8-iso-PGF(2ALPHA) isoprostane metabolism by dietary conjugated linoleic acid (CLA)

8-iso-PGF(2alpha) isoprostane (IP) is one of the most-used markers of lipid peroxidation in experimental models and humans. After its formation, it is promptly metabolized to 2,3 dinor (DIN) in peroxisomes. Conjugated linoleic acid (CLA) is preferentially beta-oxidized in peroxisomes which may compete with IP, and thereby may affect its metabolism. In order to verify whether CLA is able to influence IP formation and/or metabolism and to explain the mechanism, we challenged rats supplemented with CLA or with triolein (as a control fatty acid), with a single dose of carbon tetrachloride (CCl(4)) or of bacterial lipopolysaccharide (LPS). The results showed that IP and its precursor arachidonic acid hydroperoxide, as well as malondialdehyde (MDA), increase significantly in the liver of rats challenged with CCl(4), irrespective of the diet, while in LPS-treated rats only nitrites in liver and isoprostane in plasma increase. On the other hand, the peroxisomal beta-oxidation products of IP, the DIN, is significantly lower in the CLA group with respect to control and triolein groups. To further investigate whether this is due to competition between CLA and IP at the cellular level, we incubated human fibroblasts from healthy subjects or patients with adrenoleukodystrophy (ALD), with CLA and/or commercially available IP. The rationale of this approach is based on the deficient peroxisomal beta-oxidation of fibroblasts from ALD patients, leading to a reduced formation of DIN. In both normal and ALD cells, the presence of CLA significantly inhibits the formation of DIN from IP. We may conclude that both in vitro and in vivo studies strongly suggest that CLA may impair IP catabolism in peroxisomes. Consequently an increase of IP, as a sole result of CLA intake, cannot be considered as a marker of lipid peroxidation.

Kupffer cell products and interleukin 1beta directly promote VLDL secretion and apoB mRNA up-regulation in rodent hepatocytes

Plasma VLDL accumulation in Gram-negative sepsis is partly ascribed to an increased hepatic VLDL production driven by pro-inflammatory cytokines. We previously showed that hepatocytes of the Kupffer cell (KC)-rich periportal area are major contributors to enhanced VLDL production in lipopolysaccharide (LPS)-injected rats. However, it remains to be established whether KC generated products directly affect the number (apoB) and composition of secreted VLDL. Using rat primary cells, we show here that hepatocytes respond to stimulation by soluble mediators released by LPS-stimulated Kupffer cells with enhanced secretion of apoB and triglycerides in phospholipid-rich VLDL particles. Unstimulated KC products also augmented the secretion of normal VLDL, doubling apoB mRNA abundance. IL-1beta treatment resulted in concentration-dependent increases of hepatocyte apoB mRNA and protein secretion, increases that were greater, but not additive, when combined with IL-6 and TNF-alpha. Lipid secretion and MTP mRNA levels were unaffected by cytokines. In summary: (i) enhanced secretion of phospholipid-rich VLDL particles is a net hepatocyte response to LPS-stimulated KC products, which gives a clue about the local role of Kupffer cells in septic dyslipidemia induction; and (ii) pro-inflammatory cytokines act redundantly to enhance apoB secretion involving translational apoB up-regulation, but other humoral components or KC mediators are necessary to accomplish increased lipid association.

Bacterial endotoxin stimulates adipose lipolysis via toll-like receptor 4 and extracellular signal-regulated kinase pathway

Bacterial endotoxin/lipopolysaccharide elicits inflammatory responses and also elevates circulating levels of free fatty acids (FFAs) and impairs insulin sensitivity. Serum FFA elevation in acute endotoxemia has long been thought to be due to endotoxin dysregulating lipid disposal and counterregulatory hormones and cytokines. Here, we investigated the direct lipolysis effect of endotoxin in rodents and in isolated primary adipocytes. Endotoxin increases lipolysis in vivo in adipose tissues, elevates circulating FFA level, induces insulin resistance in rats, and directly stimulates chronic lipolysis in vitro in adipocytes. The lipolytic action of endotoxin is mediated via its lipid A moiety and is blocked by anti-endotoxin peptides. Neither adipocytokine secretion nor nuclear factor-kappaB activation is involved in endotoxin-induced lipolysis. Different from catecholamine, endotoxin stimulates lipolysis without elevating cAMP production and activating protein kinase A and protein kinase C. Instead, endotoxin induces phosphorylation of Raf-1, MEK1/2, and ERK1/2. Upon inhibition of ERK1/2 but not JNK and p38 MAPK, endotoxin-stimulated lipolysis ceases. Endotoxin causes perilipin down-regulation and phosphorylation and increases the activity and protein levels of hormone-sensitive lipase and adipose triglyceride lipase but does not induce hormone-sensitive lipase translocation to intracellular lipid droplets. In TLR4 (Toll-like receptor 4)-deficient mice and adipocytes, endotoxin fails to increase in vivo and in vitro lipolysis. These findings suggest that endotoxin stimulates lipolysis via TLR4 and ERK1/2 signaling in adipocytes. The lipolytic action of endotoxin liberates FFA efflux from adipocytes to the bloodstream, which is a possible basis for systemic FFA elevation and insulin resistance in endotoxemia or Gram-negative bacterial infection.

Effect of the orlistat on serum endotoxin lipopolysaccharide and adipocytokines in South Asian individuals with impaired glucose tolerance

BACKGROUND

Orlistat has been shown to increase adiponectin and reduce progression to type 2 diabetes in obese Caucasians. Some effects of orlistat are thought to be independent of weight loss by altering gut flora and the production of endotoxin lipopolysaccharide (LPS). We studied the effect of dietary treatment with and without orlistat in South Asian individuals with impaired glucose tolerance (IGT) on adiponectin and inflammatory markers including LPS.

METHODS

South Asian individuals were randomised to either dietary treatment with orlistat or dietary treatment alone. At the end of 12 months, a comparison was made between the two groups for differences in anthropomorphic measurements and serum markers.

RESULTS

Three hundred and five individuals underwent oral glucose tolerance test of whom 40 had IGT. Complete baseline and 1-year data was available for 31 patients. After 1 year, patients in the orlistat group demonstrated a greater but insignificant decrease in weight (4.5 +/- 0.1 kg), and a significant increase in adiponectin (6.73 +/- 3.2 microg/ml) and decrease in LPS (4.55 +/- 1.98 EU/ml) compared with- the diet-alone group. In the orlistat group the reduction in LPS was correlated with the increase in adiponectin (p < 0.005).

CONCLUSION

The increase in adiponectin levels in the orlistat group would suggest that orlistat may reduce the progression to type 2 diabetes in South Asian individuals by raising serum adiponectin. The finding that LPS levels are also reduced by orlistat and that this reduction correlates with the increase in adiponectin raises the possibility that the increase in adiponectin may be mediated via an effect on LPS levels.

LPS decreases fatty acid oxidation and nuclear hormone receptors in the kidney

Inflammation produces marked changes in lipid metabolism, including increased serum fatty acids (FAs) and triglycerides (TGs), increased hepatic TG production and VLDL secretion, increased adipose tissue lipolysis, and decreased FA oxidation in liver and heart. Lipopolysaccharide (LPS) also increases TG and cholesteryl ester levels in kidneys. Here we confirm these findings and define potential mechanisms. LPS decreases renal FA oxidation by 40% and the expression of key proteins required for oxidation of FAs, including FA transport protein-2, fatty acyl-CoA synthase, carnitine palmitoyltransferase-1, medium-chain acyl-CoA dehydrogenase, and acyl-CoA oxidase. Similar decreases were observed in peroxisome proliferator-activated receptor alpha (PPARalpha)-deficient mice. LPS also caused a reduction in renal mRNA levels of PPARalpha (75% decrease), thyroid hormone receptor alpha (TRalpha) (92% decrease), and TRbeta (84% decrease), whereas PPARbeta/delta and gamma were not altered. Expression of PGC1 alpha and beta, coactivators required for PPARs and TR, was also decreased in kidneys of LPS-treated mice, as were mitochondrial genes regulated by PGC1 (Atp5g1, COX5a, Idh3a, and Ndufs8). Decreased renal FA oxidation could be a by-product of the systemic coordinated host response to increase FAs and TGs available for host defense and/or tissue repair. However, the kidney requires energy to support its transport functions, and the inability to generate energy via FA oxidation might contribute to the renal failure seen in severe sepsis.

Infection induces a positive acute phase apolipoprotein E response from a negative acute phase gene: role of hepatic LDL receptors

Apolipoprotein E (apoE) plays important roles in lipid homeostasis, anti-inflammation, and host defense. Since tissue apoE mRNA levels have been reported to decrease during inflammatory responses, we were surprised to find that plasma apoE levels were significantly elevated during septic infections in both humans and mice. This apparent paradox was also observed during lipopolysaccharide-induced acute inflammation in mice: plasma levels of apoE increased up to 4-fold despite sharply decreased apoE gene expression in the liver, macrophages, and extrahepatic tissues. We hypothesized that apoE levels were augmented by decreased plasma clearance. Our analysis revealed that apoE associated principally with HDL in mice and that apoE was cleared from the circulation principally via LDL receptors. The acute inflammatory response decreased LDL receptor expression in the liver and significantly reduced the rate of apoE clearance. In contrast, the same inflammatory stimuli increased LDL receptor expression in macrophages. Our results define a novel acute phase mechanism that increases circulating apoE levels as apoE production decreases. Diminished hepatic LDL receptor expression may thus cooperate with elevated LDL receptor expression in macrophages to facilitate the forward transport of apoE and its associated lipids to these key defense cells.

Atherogenic lipoprotein parameters in patients with aggressive periodontitis

BACKGROUND AND OBJECTIVE

Certain types of chronic infection increase the plasma level of very-low-density lipoprotein, leading to formation of the particularly atherogenic low-density lipoprotein subclass, small dense low-density lipoprotein. In the present study, we examined whether aggressive forms of periodontitis are associated with these atherogenic lipoprotein parameters.

MATERIAL AND METHODS

Twelve healthy control subjects without periodontitis, 12 subjects with localized aggressive periodontitis and 12 subjects with generalized aggressive periodontitis were studied. Lipoprotein subclass levels were determined using nuclear magnetic resonance methodology.

RESULTS

Healthy control subjects, localized aggressive periodontitis subjects and generalized aggressive periodontitis subjects had progressively higher plasma levels of very-low-density lipoprotein and progressively smaller average low-density lipoprotein size (p < 0.05, one-way analysis of variance). In pairwise comparisons, differences were only significant between healthy controls and generalized aggressive periodontitis subjects (p < 0.05, Tukey's post test). After adjustment for body mass index, the mean periodontal pocket depth correlated positively with plasma very-low-density lipoprotein levels (p = 0.047). Very-low-density lipoprotein concentrations correlated positively with small dense low-density lipoprotein levels and negatively with average low-density lipoprotein size. Prevalence of the atherogenic lipoprotein pattern-B in healthy controls, localized aggressive periodontitis subjects and generalized aggressive periodontitis subjects was 8.3%, 33.3% and 66.6%, respectively.

CONCLUSION

These results indicate that periodontal infection is associated with elevated plasma levels of atherogenic lipoprotein species. This association may account for the increased risk of periodontitis patients for cardiovascular disease.

Infection and inflammation decrease apolipoprotein M expression

Inflammation can produce abnormalities that could increase the risk for atherosclerosis including alterations in lipid and lipoprotein metabolism. Apolipoprotein M is a recently described HDL-associated apoprotein expressed mainly in the liver and kidney with protective effects against atherosclerosis. In this study, we describe the regulation of apolipoprotein M during the acute phase response. Stimuli that produce systemic inflammation, LPS, zymosan, or turpentine, decrease apolipoprotein M mRNA levels in the liver and kidney. Treatment of Hep3B hepatoma cells with TNF or IL-1 also decreased apolipoprotein M mRNA levels. The decrease in apolipoprotein M mRNA leads to a decrease in apolipoprotein M secretion into the media in Hep3B cells and a decrease in mouse serum following LPS administration. Moreover, in humans with acute bacterial infections or chronic HIV infection, serum apolipoprotein M levels are decreased. Apolipoprotein M is a negative acute response protein that decreases during infection and inflammation. These results are consistent with the finding that infections and inflammatory disorders accompanied by systemic inflammation are associated with an increased risk of atherosclerosis.

Lipopolysaccharide induces adipose differentiation-related protein expression and lipid accumulation in the liver through inhibition of fatty acid oxidation in mice

BACKGROUND

In the present study, we examined the effect of lipopolysaccharide (LPS) on liver histopathology with special reference to lipid metabolism in mice.

METHODS

Mice were injected with LPS intraperitoneally, and its effect on the liver was investigated pathologically and biochemically.

RESULTS

Oil-red O staining and adipose differentiation-related protein (ADRP) immunohistochemistry demonstrated that injection of LPS transiently induced lipid accumulation and ADRP expression in hepatocytes, especially around the portal vein. Microscopic observation revealed that lipid accumulation started 12 h after LPS injection. Time-course studies showed that LPS rapidly, within 2 h, decreased hepatic expression of nuclear hormone receptors, including peroxisome proliferator-activated receptor (PPAR) alpha. LPS inhibited the expression of PPARalpha-target genes involved in fatty acid oxidation in the liver such as those coding for enoyl-CoA hydratase, acyl-CoA dehydrogenase, and carnitine palmitoyl transferase-1, whereas LPS also suppressed the expression of genes related to fatty acid synthesis such as those for fatty acid synthase, stearoyl-CoA desaturase, and acetyl-CoA carboxylase alpha.

CONCLUSIONS

LPS induces transient lipid accumulation and expression of ADRP in the liver through inhibition of fatty acid oxidation by downregulation of the PPARalpha-related transcriptional mechanism.

Apolipoprotein C-I is crucially involved in lipopolysaccharide-induced atherosclerosis development in apolipoprotein E-knockout mice

BACKGROUND

Lipopolysaccharide (LPS), which is released from gram-negative bacteria on multiplication or lysis, aggravates atherosclerosis in humans and rodents by inducing inflammation via toll-like receptors. Because apolipoprotein C-I (apoCI) enhances the LPS-induced inflammatory response in macrophages in vitro and in mice, we investigated the effect of endogenous apoCI expression on LPS-induced atherosclerosis in mice.

METHODS AND RESULTS

Twelve-week-old apoe-/- apoc1-/- and apoe-/- apoc1+/+ mice received weekly intraperitoneal injections of LPS (50 microg) or vehicle for a period of 10 weeks, and atherosclerosis development was assessed in the aortic root. LPS administration did not affect atherosclerotic lesion area in apoe-/- apoc1-/- mice but increased it in apoe-/- apoc1+/+ mice. In fact, apoCI expression increased the LPS-induced atherosclerotic lesion area by 60% (P<0.05), concomitant with an increase in LPS-induced plasma levels of fibrinogen and E-selectin. This indicated that apoCI increased the LPS-induced inflammatory state, both systemically (ie, fibrinogen) and at the level of the vessel wall (ie, E-selectin). In addition, both macrophage-derived apoCI and HDL-associated apoCI increased the LPS-induced tumor necrosis factor-alpha response by macrophages in vitro.

CONCLUSIONS

We conclude that apoCI is crucially involved in LPS-induced atherosclerosis in apoe-/- mice, which mainly relates to an increased inflammatory response toward LPS. We anticipate that apoCI plasma levels contribute to accelerated atherosclerosis development in individuals who have chronic infection.

Alterations in lipoprotein homeostasis during human experimental endotoxemia and clinical sepsis

Cell wall constituents of bacteria are potent endotoxins initiating inflammatory responses which may cause dramatic changes in lipid metabolism during the acute phase response. In this study, the sequential changes in lipoprotein composition and lipid transfer and binding proteins during clinical sepsis and during low-dose experimental endotoxemia were followed. In addition, the effect on (phospho)lipid homeostasis by administration of reconstituted HDL (rHDL) prior to low-dose LPS administration was investigated. Changes in (apo)lipoprotein concentrations typical of the acute phase response were observed during clinical sepsis and experimental endotoxemia with and without the rHDL intervention. During clinical sepsis negative correlations between the acute phase marker C-reactive protein (CRP) and lecithin:cholesterol acyltransferase (LCAT) and cholesterylester transfer protein (CETP) activities were seen, whereas positive correlations between plasma phospholipid transfer protein (PLTP) activity and acute phase markers such as CRP and LPS binding protein were observed. Plasma lipid changes upon rHDL/LPS infusion were comparable with the control group (low-dose LPS only). PLTP activity decreased upon LPS infusion and transiently increased during rHDL infusion, whereas LCAT activity slightly decreased upon both LPS infusion and LPS/rHDL infusion. However, long-lasting increases of circulating HDL cholesterol, apo A-I and a high initial processing of both phosphatidylcholine (PC) and lyso-PC, were indicative for extensive rHDL and LDL remodelling. Both sepsis and experimental endotoxemia lead to a disbalance of lipid homeostasis. Depending on the magnitude of the inflammatory stimulus, LCAT and PLTP activities reacted in divergent ways. rHDL infusion did not prevent the lipid alterations seen during the acute phase response. However profound changes in both HDL and LDL phospholipid composition occurred upon rHDL infusion. This may be explained, at least in part, by the fact that PLTP as a positive acute phase protein, can accelerate the alterations in (phospho)lipid homeostasis thereby playing a role in the attenuation of the acute phase response.

Changes in plasma LDL and HDL composition in patients undergoing cardiac surgery

Changes of lipoprotein composition have been mainly reported in conditions of sepsis. This study characterized compositional changes in LDL and HDL during the acute phase response following cardiac surgery with cardiopulmonary bypass. Twenty-one patients undergoing cardiac surgery were included in this study. Blood samples were drawn before operation and on day 2 post-surgery. In parallel to plasma lipids and antioxidant status, lipoproteins were analyzed for lipid, apolipoprotein (apo), hydroperoxide and alpha-tocopherol content. Beyond decreases in lipid concentrations and antioxidant defenses, cardiac surgery induced substantial modifications in plasma lipoproteins. ApoB decrease in LDL fraction (-46%; P < 0.0001) reflected a marked reduction in the circulating particle number. LDL cholesteryl ester content relative to apoB concentration remained unchanged post-surgery while triglyceride (+113%; P < 0.001), free cholesterol (+22%; P < 0.05) and phospholipid (+23%; P < 0.025) were raised relative to apoB indicating increased particle size. In HDL, an abrupt rise of apoSAA (P < 0.05) was observed together with a decrease of apoA1 (-22%; P < 0.005). Cholesteryl ester content in HDL fraction decreased in parallel to apoA1 concentration while triglycerides, free cholesterol and phospholipids increased relative to apoA1. In contrast to unchanged alpha-tocopherol content, hydroperoxide content was increased in LDL and HDL. By comparison to sepsis, cardiac surgery induces a comparable reduction in circulating LDL but a more limited decrease in HDL particles. Furthermore, in contrast, cardiac surgery induces an increase in polar and non-polar lipids, as well as of particle size in both LDL and HDL.

Beneficial Effects of Periodontal Treatment on Metabolic Control of Hypercholesterolemia

BACKGROUND

The authors aimed to evaluate whether local periodontal therapy may influence plasma lipid levels in patients with periodontitis.

METHODS

Fifty patients (31 females and 19 males, age 36-66 yr) were randomly assigned to the treatment and control groups. Lipid profile and dental variables were measured at baseline and at the end of the study in both groups.

RESULTS

In the third month, there was a significant decrease in total and low density lipoprotein (LDL) cholesterol levels of the treatment group compared with baseline values. Also, the reduction in bleeding on probing, pocket depth, attachment loss, plaque index and gingival index were statistically significant in the treatment group.

CONCLUSIONS

The present study indicates that periodontitis causes changes in total and LDL cholesterol levels and local periodontal treatment resulted in a significant decrease in these markers. These results suggest a potential effect of periodontitis-driven systemic inflammation on lipid metabolism.

Suppression of N-nitrosobis(2-oxopropyl)amine-induced pancreatic carcinogenesis in hamsters by pioglitazone, a ligand of peroxisome proliferator-activated receptor γ

Fat intake and obesity are positively correlated with pancreatic cancer in humans. N-nitrosobis(2-oxopropyl)amine (BOP) induces pancreatic ductal adenocarcinomas limited to Syrian golden hamsters, other rodents not being susceptible. In the present study, we found markedly high levels of serum triglycerides (TGs) and total cholesterol (TC) in Syrian golden hamsters, but not C57BL/6 mice, ICR mice, F344 rats and Wistar rats. Consistent with this, lipoprotein lipase (LPL) activities in the liver were lower in hamsters compared with mice and rats. To examine effects of pioglitazone, a peroxisome proliferator-activated receptor gamma (PPARgamma) ligand, on LPL expression, serum lipid levels and pancreatic cancer development, 6-week-old female Syrian golden hamsters were subcutaneously injected with BOP (10 mg/kg body wt) four times in a week and thereafter fed a diet containing 800 p.p.m. pioglitazone for 22 weeks. The treatment elevated LPL mRNA expression in the liver and significantly improved hyperlipidemia with serum levels of TG and TC being decreased to 62 and 71%, respectively, of the control values. Concurrently, the incidence and multiplicity of pancreatic ductal adenocarcinomas were significantly decreased by pioglitazone in comparison with the controls (38 versus 80%, P < 0.01 and 0.55 +/- 0.15 versus 1.37 +/- 0.22, P < 0.01, respectively). The suppression rates were greater in invasive adenocarcinomas than non-invasive ones. The incidence of cholangiocellular carcinomas was also reduced. Thus, suppression of pancreatic adenocarcinoma development by pioglitazone is possibly associated with improvement in the serum lipid profile, and hyperlipidemia could be an enhancing factor for development of pancreatic cancer in hamsters.