Apo A-IV: an update on regulation and physiologic functions

Hepatic Transcriptomics of Broilers with Low and High Feed Conversion in Response to Caloric Restriction

BACKGROUND

In broiler chickens, the efficient utilization of macro- and micronutrients is influenced by various metabolic pathways that are closely linked to feed efficiency (FE), a critical metric in poultry industry, with residual feed intake (RFI) as the preferred proxy. Feed restriction is considered an approach to address the underlying molecular mechanisms of feed conversion. We hypothesized that broiler chickens with divergent RFI subjected to quantitative feed restriction differ in their pattern of molecular pathways for efficient nutrient utilization in liver as post-absorptive tissue.

METHODS

Cobb 500FF broiler chickens divergent for RFI (n = 112) were feed-restricted from day 9 until market weight at day 33-37 post-hatch. Based on a previous trial, feed restriction levels were set at 92% (low-RFI birds) and 80% (high-RFI birds) relative to the control groups. Transcriptomic analyses of the liver were conducted.

RESULTS

Due to the interaction of the RFI group and feeding regimen, a total of 140 to 507 differentially expressed genes were identified for the respective contrasts, with implications for hepatic metabolism and cellular stress response. Although the broilers did not realize their full growth potential under restrictive feeding (12.4% reduced body weight vs. controls, p = 0.094), the gene expression patterns indicate a lower susceptibility to blood coagulation (KNG1, FGG, and FGB), suggesting that controlled and mild feed restriction could lead to health benefits in less feed-efficient broilers. Moreover, FE traits are shown to be linked to cellular detoxification processes (MGST3 and CYP2AC2) and triacylglycerol syntheses (MOGAT1 and LPIN1).

CONCLUSIONS

Divergent transcriptional profiles between broiler groups under varied caloric conditions indicate potential for optimizing nutritional management strategies.

Cholesterol transport and beyond: Illuminating the versatile functions of HDL apolipoproteins through structural insights and functional implications

High-density lipoproteins (HDLs) play a vital role in lipid metabolism and cardiovascular health, as they are intricately involved in cholesterol transport and inflammation modulation. The proteome of HDL particles is indeed complex and distinct from other components in the bloodstream. Proteomics studies have identified nearly 285 different proteins associated with HDL; however, this review focuses more on the 15 or so traditionally named "apo" lipoproteins. Important lipid metabolizing enzymes closely working with the apolipoproteins are also discussed. Apolipoproteins stand out for their integral role in HDL stability, structure, function, and metabolism. The unique structure and functions of each apolipoprotein influence important processes such as inflammation regulation and lipid metabolism. These interactions also shape the stability and performance of HDL particles. HDLs apolipoproteins have multifaceted roles beyond cardiovascular diseases (CVDs) and are involved in various physiological processes and disease states. Therefore, a detailed exploration of these apolipoproteins can offer valuable insights into potential diagnostic markers and therapeutic targets. This comprehensive review article aims to provide an in-depth understanding of HDL apolipoproteins, highlighting their distinct structures, functions, and contributions to various physiological processes. Exploiting this knowledge holds great potential for improving HDL function, enhancing cholesterol efflux, and modulating inflammatory processes, ultimately benefiting individuals by limiting the risks associated with CVDs and other inflammation-based pathologies. Understanding the nature of all 15 apolipoproteins expands our knowledge of HDL metabolism, sheds light on their pathological implications, and paves the way for advancements in the diagnosis, prevention, and treatment of lipid and inflammatory-related disorders.

Genetic determinants of inherited susceptibility to hypercholesterolemia - a comprehensive literature review

Hypercholesterolemia is a strong determinant of mortality and morbidity associated with cardiovascular diseases and a major contributor to the global disease burden. Mutations in four genes (LDLR, APOB, PCSK9 and LDLRAP1) account for the majority of cases with familial hypercholesterolemia. However, a substantial proportion of adults with hypercholesterolemia do not have a mutation in any of these four genes. This indicates the probability of having other genes with a causative or contributory role in the pathogenesis of hypercholesterolemia and suggests a polygenic inheritance of this condition. Here in, we review the recent evidence of association of the genetic variants with hypercholesterolemia and the three lipid traits; total cholesterol (TC), HDL-cholesterol (HDL-C) and LDL-cholesterol (LDL-C), their biological pathways and the associated pathogenetic mechanisms. Nearly 80 genes involved in lipid metabolism (encoding structural components of lipoproteins, lipoprotein receptors and related proteins, enzymes, lipid transporters, lipid transfer proteins, and activators or inhibitors of protein function and gene transcription) with single nucleotide variants (SNVs) that are recognized to be associated with hypercholesterolemia and serum lipid traits in genome-wide association studies and candidate gene studies were identified. In addition, genome-wide association studies in different populations have identified SNVs associated with TC, HDL-C and LDL-C in nearly 120 genes within or in the vicinity of the genes that are not known to be involved in lipid metabolism. Over 90% of the SNVs in both these groups are located outside the coding regions of the genes. These findings indicates that there might be a considerable number of unrecognized processes and mechanisms of lipid homeostasis, which when disrupted, would lead to hypercholesterolemia. Knowledge of these molecular pathways will enable the discovery of novel treatment and preventive methods as well as identify the biochemical and molecular markers for the risk prediction and early detection of this common, yet potentially debilitating condition.

ApoA-IV improves insulin sensitivity and glucose uptake in mouse adipocytes via PI3K-Akt Signaling

Insulin resistance is a risk factor for type 2 diabetes mellitus. We investigated the effect of ApoA-IV on glucose uptake in the adipose and muscle tissues of mice and cultured 3T3-L1 adipocytes. We found that treatment with ApoA-IV lowered fasting blood glucose in both WT and diabetic KKAy mice by increasing glucose uptake in cardiac muscle, white adipose tissue, and brown adipose tissue through a mechanism that was partially insulin independent. Cell culture experiments showed that ApoA-IV improved glucose uptake in adipocytes in the absence of insulin by upregulating GLUT4 translocation by PI3K mediated activation of Akt signaling pathways. Considering our previous finding that ApoA-IV treatment enhanced pancreatic insulin secretion, these results suggests that ApoA-IV acts directly upon adipose tissue to improve glucose uptake and indirectly via insulin signaling. Our findings warrant future studies to identify the receptor for ApoA-IV and the downstream targets of PI3K-Akt signaling that regulate glucose uptake in adipocytes as potential therapeutic targets for treating insulin resistance.

Blood-based immune-endocrine biomarkers of treatment response in depression

Antidepressant treatment for major depressive disorder remains suboptimal with response rates of just over 50%. Although treatment guidelines, algorithms and clinical keys are available to assist the clinician, the process of finding an effective pharmacotherapy to maximise benefit for the individual patient is largely by "trial and error" and remains challenging. This highlights a clear need to identify biomarkers of treatment response to help guide personalised treatment strategies. We have carried out the largest multiplex immunoassay based longitudinal study to date, examining up to 258 serum markers involved in immune, endocrine and metabolic processes as potential biomarkers associated with treatment response in 332 depression patients recruited from four independent clinical centres. We demonstrated for the first time that circulating Apolipoprotein A-IV, Endoglin, Intercellular Adhesion Molecule 1, Tissue Inhibitor of Metalloproteinases 1, Plasminogen Activator Inhibitor 1, Thrombopoietin, Complement C3, Hepatocyte Growth Factor and Insulin-like Growth Factor-Binding Protein 2 were associated with response to different antidepressants. In addition, we showed that specific sets of immune-endocrine proteins were associated with response to Venlafaxine (serotonin-norepinephrine reuptake inhibitor), Imipramine (tricyclic antidepressant) and other antidepressant drugs. However, we were not able to reproduce the literature findings on BDNF and TNF-α, two of the most commonly reported candidate treatment response markers. Despite the need for extensive validation studies, our preliminary findings suggest that a pre-treatment immune-endocrine profile may help to determine a patient's likelihood to respond to specific antidepressant and/or alternative treatments such as anti-inflammatory drugs, providing hope for future personalised treatment approaches.

Korean pine nut oil replacement decreases intestinal lipid uptake while improves hepatic lipid metabolism in mice

BACKGROUND/OBJECTIVES

Consumption of pine nut oil (PNO) was shown to reduce weight gain and attenuate hepatic steatosis in mice fed a high-fat diet (HFD). The aim of this study was to examine the effects of PNO on both intestinal and hepatic lipid metabolism in mice fed control or HFD.

MATERIALS/METHODS

Five-week-old C57BL/6 mice were fed control diets containing 10% energy fat from either Soybean Oil (SBO) or PNO, or HFD containing 15% energy fat from lard and 30% energy fat from SBO or PNO for 12 weeks. Expression of genes related to intestinal fatty acid (FA) uptake and channeling (Cd36, Fatp4, Acsl5, Acbp), intestinal chylomicron synthesis (Mtp, ApoB48, ApoA4), hepatic lipid uptake and channeling (Lrp1, Fatp5, Acsl1, Acbp), hepatic triacylglycerol (TAG) lipolysis and FA oxidation (Atgl, Cpt1a, Acadl, Ehhadh, Acaa1), as well as very low-density lipoprotein (VLDL) assembly (ApoB100) were determined by real-time PCR.

RESULTS

In intestine, significantly lower Cd36 mRNA expression (P < 0.05) and a tendency of lower ApoA4 mRNA levels (P = 0.07) was observed in PNO-fed mice, indicating that PNO consumption may decrease intestinal FA uptake and chylomicron assembly. PNO consumption tended to result in higher hepatic mRNA levels of Atgl (P = 0.08) and Cpt1a (P = 0.05). Significantly higher hepatic mRNA levels of Acadl and ApoB100 were detected in mice fed PNO diet (P < 0.05). These results suggest that PNO could increase hepatic TAG metabolism; mitochondrial fatty acid oxidation and VLDL assembly.

CONCLUSIONS

PNO replacement in the diet might function in prevention of excessive lipid uptake by intestine and improve hepatic lipid metabolism in both control diet and HFD fed mice.

Distinctive proteomic profiles among different regions of human carotid plaques in men and women

The heterogeneity of atherosclerotic tissue has limited comprehension in proteomic and metabolomic analyses. To elucidate the functional implications, and differences between genders, of atherosclerotic lesion formation we investigated protein profiles from different regions of human carotid atherosclerotic arteries; internal control, fatty streak, plaque shoulder, plaque centre, and fibrous cap. Proteomic analysis was performed using 2-DE with MALDI-TOF, with validation using nLC-MS/MS. Protein mapping of 2-DE identified 52 unique proteins, including 15 previously unmapped proteins, of which 41 proteins were confirmed by nLC-MS/MS analysis. Expression levels of 18 proteins were significantly altered in plaque regions compared to the internal control region. Nine proteins showed site-specific alterations, irrespective of gender, with clear associations to extracellular matrix remodelling. Five proteins display gender-specific alterations with 2-DE, with two alterations validated by nLC-MS/MS. Gender differences in ferritin light chain and transthyretin were validated using both techniques. Validation of immunohistochemistry confirmed significantly higher levels of ferritin in plaques from male patients. Proteomic analysis of different plaque regions has reduced the effects of plaque heterogeneity, and significant differences in protein expression are determined in specific regions and between genders. These proteomes have functional implications in plaque progression and are of importance in understanding gender differences in atherosclerosis.

Plaque stabilizing effects of apolipoprotein A-IV

BACKGROUND AND AIMS

Apolipoprotein (apo) A-IV, the third most abundant HDL-associated protein, is atheroprotective and shares similar properties as apoA-I. We have reported previously that apoA-I, the most abundant apolipoprotein in HDL, inhibits plaque disruption in a mouse model. We aimed at examining the effects of apoA-IV on markers of plaque stability in vivo.

METHODS

Plaques within brachiocephalic arteries of 16-week old apoE-knockout C57BL/6 mice were examined for changes in composition after 10 weeks on a high-fat diet (HFD). The animals received twice-weekly injections of human lipid-free apoA-IV (1 mg/kg, n = 31) or PBS (n = 32) during the 9th and 10th weeks of the HFD.

RESULTS

In the apoA-IV treated mice, there were significantly fewer hemorrhagic plaque disruptions (9/31 vs. 18/32, p < 0.05), thicker fibrous caps, smaller lipid cores, a lower macrophage:SMC ratio, less MMP-9 protein, more collagen, and fewer proliferating cells. In the plaques of mice given apoA-IV, MCP-1, VCAM-1, and inducible NOS were also significantly lower. Based on the percentage of cleaved PARP-positive and TUNEL-positive plaque nuclei, apoA-IV reduced apoptosis. in HMDMs, apoA-IV reduced MMP-9 mRNA expression by half, doubled mRNA levels of TIMP1 and decreased MMP-9 activity.

CONCLUSIONS

ApoA-IV treatment is associated with a more stable plaque phenotype and a reduced incidence of acute disruptions in this mouse model.

Acute phase plasma proteins are altered by electroconvulsive stimulation

Electroconvulsive therapy (ECT) is an effective antidepressant treatment, but its molecular mechanisms of action remain to be fully elucidated. To better understand the effects of ECT, we conducted a proteomic study to characterize global changes in plasma protein abundance induced by electroconvulsive stimulation (ECS) in the animal model equivalent of ECT. Male Sprague-Dawley rats were administered a single or repeat (10 sessions) course of ECS, and compared with sham-ECS administered animals. Quantitative differential protein expression analysis was performed, using 2-dimensional difference in gel electrophoresis (2D DiGE), on immunodepleted plasma. Proteins were selected for identification by liquid chromatography tandem mass spectrometry (LC-MS/MS): 150 protein spots were significantly altered following a single ECS and 178, following repeated ECS. In total, 18 proteins were identified by LC-MS/MS. Many of these were acute-phase response proteins, previously reported to be increased in depressed patients. Changes in the abundance of two proteins of interest were confirmed by other measures. Repeat ECS was found to significantly reduce plasma levels of haptoglobin and apolipoprotein A-IV, although these changes were no longer evident 4 weeks after the repeated ECS. Our results implicate the immune system-induced acute phase protein response in ECS action while identifying potential plasma biomarkers for ECS.

Specific expression of apolipoprotein A-IV in the follicle-associated epithelium of the small intestine

BACKGROUND

Peyer's patches (PPs), which are covered by specialized follicle-associated epithelium (FAE) including M cells, play a central role in immune induction in the gastrointestinal tract. This study is to investigate a new molecule to characterize PPs.

METHODS

We generated a monoclonal antibody (mAb 10-15-3-3) that specifically reacts to the epithelium of PPs and isolated lymphoid follicles. Target antigen was analyzed by immunoprecipitation and mass spectrometry. Localization and expression of target antigen were evaluated by immunofluorescence, in situ hybridization and real-time PCR.

RESULTS

Immunoprecipitation and mass spectrometry revealed that mAb 10-15-3-3 recognized apolipoprotein A-IV (ApoA-IV), a well-known lipid transporter; this finding was confirmed by the specific reactivity of mAb 10-15-3-3 to cells transfected with the murine ApoA-IV gene. Immunofluorescence using mAb 10-15-3-3 showed intestinal localization of ApoA-IV, in which strong expression of the ApoA-IV protein occurred throughout the entire intestinal epithelium during developing period before weaning but was restricted to the FAE in adult mice. In support of these findings, in situ hybridization showed strong expression of the ApoA-IV gene throughout the entire intestinal epithelium during developing period before weaning, but this expression was restricted to the FAE predominantly and the tips of villi to a lesser extent in adult mice. Deficiency of ApoA-IV had no effect on the organogenesis of PP in mice.

CONCLUSIONS

Our current results reveal ApoA-IV as a novel FAE-specific marker especially in the upper small intestine of adult mice.

The development of diet-induced obesity and glucose intolerance in C57BL/6 mice on a high-fat diet consists of distinct phases

High-fat (HF) diet-induced obesity and insulin insensitivity are associated with inflammation, particularly in white adipose tissue (WAT). However, insulin insensitivity is apparent within days of HF feeding when gains in adiposity and changes in markers of inflammation are relatively minor. To investigate further the effects of HF diet, C57Bl/6J mice were fed either a low (LF) or HF diet for 3 days to 16 weeks, or fed the HF-diet matched to the caloric intake of the LF diet (PF) for 3 days or 1 week, with the time course of glucose tolerance and inflammatory gene expression measured in liver, muscle and WAT. HF fed mice gained adiposity and liver lipid steadily over 16 weeks, but developed glucose intolerance, assessed by intraperitoneal glucose tolerance tests (IPGTT), in two phases. The first phase, after 3 days, resulted in a 50% increase in area under the curve (AUC) for HF and PF mice, which improved to 30% after 1 week and remained stable until 12 weeks. Between 12 and 16 weeks the difference in AUC increased to 60%, when gene markers of inflammation appeared in WAT and muscle but not in liver. Plasma proteomics were used to reveal an acute phase response at day 3. Data from PF mice reveals that glucose intolerance and the acute phase response are the result of the HF composition of the diet and increased caloric intake respectively. Thus, the initial increase in glucose intolerance due to a HF diet occurs concurrently with an acute phase response but these effects are caused by different properties of the diet. The second increase in glucose intolerance occurs between 12-16 weeks of HF diet and is correlated with WAT and muscle inflammation. Between these times glucose tolerance remains stable and markers of inflammation are undetectable.

The effect of colostrum intake on blood plasma proteome profile in newborn lambs: low abundance proteins

BACKGROUND

Colostrum intake by newborn lambs plays a fundamental role in the perinatal period, ensuring lamb survival. In this study, blood plasma samples from two groups of newborn lambs (Colostrum group and Delayed Colostrum group) at 2 and 14 h after birth were treated to reduce the content of high abundance proteins and analyzed using Two-Dimensional Differential in Gel Electrophoresis and MALDI MS/MS for protein identification in order to investigate low abundance proteins with immune function in newborn lambs.

RESULTS

The results showed that four proteins were increased in the blood plasma of lambs due to colostrum intake. These proteins have not been previously described as increased in blood plasma of newborn ruminants by colostrum intake. Moreover, these proteins have been described as having an immune function in other species, some of which were previously identified in colostrum and milk.

CONCLUSIONS

In conclusion, colostrum intake modified the low abundance proteome profile of blood plasma from newborn lambs, increasing the concentration of apolipoprotein A-IV, plasminogen, serum amyloid A and fibrinogen, demonstrating that colostrum is essential, not only for the provision of immunoglobulins, but also because of increases in several low abundance proteins with immune function.

Transcriptional regulation of apolipoprotein A-IV by the transcription factor CREBH

cAMP responsive element-binding protein H (CREBH) is an endoplasmic reticulum (ER) anchored transcription factor that is highly expressed in the liver and small intestine and implicated in nutrient metabolism and proinflammatory response. ApoA-IV is a glycoprotein secreted primarily by the intestine and to a lesser degree by the liver. ApoA-IV expression is suppressed in CREBH-deficient mice and strongly induced by enforced expression of the constitutively active form of CREBH, indicating that CREBH is the major transcription factor regulating Apoa4 gene expression. Here, we show that CREBH directly controls Apoa4 expression through two tandem CREBH binding sites (5'-CCACGTTG-3') located on the promoter, which are conserved between human and mouse. Chromatin immunoprecipitation and electrophoretic mobility-shift assays demonstrated specific association of CREBH with the CREBH binding sites. We also demonstrated that a substantial amount of CREBH protein was basally processed to the active nuclear form in normal mouse liver, which was further increased in steatosis induced by high-fat diet or fasting, increasing apoA-IV expression. However, we failed to find significant activation of CREBH in response to ER stress, arguing against the critical role of CREBH in ER stress response.

Acyl chain length, saturation, and hydrophobicity modulate the efficiency of dietary fatty acid absorption in adult humans

Intestinal fat absorption is known to be, overall, a highly efficient process, but much less is known about the efficiency with which individual dietary fatty acids (FA) are absorbed by the adult small intestine. We therefore measured the absorption efficiency of the major dietary FA using sucrose polybehenate (SPB) as a nonabsorbable marker and analyzed how it is modulated by acyl chain physicochemical properties and polymorphisms of proteins involved in chylomicron assembly. Dietary FA absorption efficiency was measured in 44 healthy subjects fed a standard diet containing 35% fat and 5% SPB. FA and behenic acid (BA) were measured in homogenized diets and stool samples by gas chromatography-mass spectroscopy, and coefficients of absorption for each FA were calculated as 1 - [(FA/BA)feces/(FA/BA)diet]. Absorption coefficients for saturated FA decreased with increasing chain length and hydrophobicity (mean ± SE) and ranged from 0.95 ± 0.02 for myristate (14:0), 0.80 ± 0.03 for stearate (18:0), to 0.26 ± 0.02 for arachidate (20:0). Absorption coefficients for unsaturated FA increased with increasing desaturation from 0.79 ± 0.03 for elaidic acid (18:1t), 0.96 ± 0.01 for linoleate (18:2), to near complete absorption for eicosapentaenoic (20:5) and docosahexaenoic (22:6) acids. Of several common genetic polymorphisms in key proteins involved in the chylomicron assembly pathway, only the intestinal fatty acid-binding protein-2 A54T allele (rs1799883) had any impact on FA absorption. We conclude that acyl chain length, saturation, and hydrophobicity are the major determinants of the efficiency with which dietary FA are absorbed by the adult small intestine.

Autophagosomes contribute to intracellular lipid distribution in enterocytes

Delivery of alimentary lipids induces immediate autophagic response in enterocytes. Forming autophagosomes are recruited to the ER membrane, where they capture nascent lipid droplets and later fuse with lysosomes, illustrating for the first time the role of autophagy in neutral-lipid distribution in enterocytes.

Enterocytes, the intestinal absorptive cells, have to deal with massive alimentary lipids upon food consumption. They orchestrate complex lipid-trafficking events that lead to the secretion of triglyceride-rich lipoproteins and/or the intracellular transient storage of lipids as lipid droplets (LDs). LDs originate from the endoplasmic reticulum (ER) membrane and are mainly composed of a triglyceride (TG) and cholesterol-ester core surrounded by a phospholipid and cholesterol monolayer and specific coat proteins. The pivotal role of LDs in cellular lipid homeostasis is clearly established, but processes regulating LD dynamics in enterocytes are poorly understood. Here we show that delivery of alimentary lipid micelles to polarized human enterocytes induces an immediate autophagic response, accompanied by phosphatidylinositol-3-phosphate appearance at the ER membrane. We observe a specific and rapid capture of newly synthesized LD at the ER membrane by nascent autophagosomal structures. By combining pharmacological and genetic approaches, we demonstrate that autophagy is a key player in TG targeting to lysosomes. Our results highlight the yet-unraveled role of autophagy in the regulation of TG distribution, trafficking, and turnover in human enterocytes.

Proteomic profiling of serum samples from chikungunya-infected patients provides insights into host response

BACKGROUND

Chikungunya is a highly debilitating febrile illness caused by Chikungunya virus, a single-stranded RNA virus, which is transmitted by Aedes aegypti or Aedes albopictus mosquito species. The pathogenesis and host responses in individuals infected with the chikungunya virus are not well understood at the molecular level. We carried out proteomic profiling of serum samples from chikungunya patients in order to identify molecules associated with the host response to infection by this virus.

RESULTS

Proteomic profiling of serum obtained from the infected individuals resulted in identification of 569 proteins. Of these, 63 proteins were found to be differentially expressed (≥ 2-fold) in patient as compared to control sera. These differentially expressed proteins were involved in various processes such as lipid metabolism, immune response, transport, signal transduction and apoptosis.

CONCLUSIONS

This is the first report providing a global proteomic profile of serum samples from individuals infected with the chikungunya virus. Our data provide an insight into the proteins that are involved as host response factors during an infection. These proteins include clusterin, apolipoproteins and S100A family of proteins.

Octreotide promotes weight loss via suppression of intestinal MTP and apoB48 expression in diet-induced obesity rats

OBJECTIVE

The goal of this study was to investigate the effect of octreotide on the expression of intestinal fat absorption-associated apolipoproteinB48 (apoB48), microsomal triglyceride transfer protein (MTP) and apolipoproteinAIV (apoAIV) in a high-fat diet-induced obesity rat model.

METHODS

Sprague-Dawley rats were placed into a control or high-fat diet group. Obese rats from the high-fat diet group were further divided into an obese group and an octreotide-treated group. Rats in the octreotide-treated group were subcutaneously injected with octreotide (40 μg/kg body weight) twice daily for 8 d. Body weight, fasting plasma glucose (FPG), fasting serum insulin, triglyceride (TG), total cholesterol (TC), and high density lipoprotein-cholesterol (HDL-C) were measured. Intestinal MTP, apoB48, and apoAIV expression levels were determined by real-time polymerase chain reaction, Western blot, or enzyme-linked immunosorbent assay analysis.

RESULTS

We found high-fat diet-induced obesity rats express more apoB, MTP, and apoAIV mRNA as well as apoB48 and MTP protein in the intestine than normal chow-fed rats. This observation occurred along with increased body weight, FPG, TG, TC, fasting serum insulin, and Homeostatic Model Assessment value. Octreotide intervention significantly decreased body weight and blood parameters, and down-regulated expression of apoB mRNA and apoB48 protein, as well as MTP mRNA and proteins. However, apoAIV mRNA was not significantly different between obese and octreotide-treated rats although it was decreased by 47%.

CONCLUSION

High-fat diet-induced obesity is associated with increased expression of apoB48, MTP, and apoAIV in the intestine. Octreotide intervention inhibited the overexpression of apoB48 and MTP, and consequently brought about reduced fat absorption and weight loss.

Circadian regulation of intestinal lipid absorption by apolipoprotein AIV involves forkhead transcription factors A2 and O1 and microsomal triglyceride transfer protein

We have shown previously that Clock, microsomal triglyceride transfer protein (MTP), and nocturnin are involved in the circadian regulation of intestinal lipid absorption. Here, we clarified the role of apolipoprotein AIV (apoAIV) in the diurnal regulation of plasma lipids and intestinal lipid absorption in mice. Plasma triglyceride in apoAIV(-/-) mice showed diurnal variations similar to apoAIV(+/+) mice; however, the increases in plasma triglyceride at night were significantly lower in these mice. ApoAIV(-/-) mice absorbed fewer lipids at night and showed blunted response to daytime feeding. To explain reasons for these lower responses, we measured MTP expression; intestinal MTP was low at night, and its induction after food entrainment was less in apoAIV(-/-) mice. Conversely, apoAIV overexpression increased MTP mRNA in hepatoma cells, indicating transcriptional regulation. Mechanistic studies revealed that sequences between -204/-775 bp in the MTP promoter respond to apoAIV and that apoAIV enhances expression of FoxA2 and FoxO1 transcription factors and their binding to the identified cis elements in the MTP promoter at night. Knockdown of FoxA2 and FoxO1 abolished apoAIV-mediated MTP induction. Similarly, knockdown of apoAIV in differentiated Caco-2 cells reduced MTP, FoxA2, and FoxO1 mRNA levels, cellular MTP activity, and media apoB. Moreover, FoxA2 and FoxO1 expression showed diurnal variations, and their expression was significantly lower in apoAIV(-/-) mice. These data indicate that apoAIV modulates diurnal changes in lipid absorption by regulating forkhead transcription factors and MTP and that inhibition of apoAIV expression might reduce plasma lipids.

Different protein expression patterns associated with polycystic ovary syndrome in human follicular fluid during controlled ovarian hyperstimulation

Polycystic ovary syndrome (PCOS) is one of the most common causes of anovulatory infertility, affecting 5-10% of females during their reproductive life. Currently the pathology of PCOS is largely unknown. To identify the differential protein expression in follicular fluids from PCOS and normal subjects during controlled ovarian hyperstimulation, we performed an initial proteomic study including two-dimensional gel electrophoresis (2DE) analysis and mass spectroscopy, and confirmed results by western blot. Thirty-two protein spots were shown to be significantly differentially expressed between PCOS and normal follicular fluids, of which 20 unique proteins were identified to be associated with cellular metabolism and physiological processes; 13 of these proteins were upregulated while seven were downregulated in PCOS follicular fluids. Western blotting analyses confirmed the differential expressions for three randomly selected proteins, i.e. upregulated α1-antitrypsin, apolipoprotein A-I and transferrin in follicular fluid from PCOS patients than normal controls. Furthermore, semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) analyses revealed that mRNA levels of serine palmitoyltransferase 2, serine/threonine-protein kinase male germ cell-associated kinase (MAK) and DNA damage-regulated autophagy modulator protein 2 decreased significantly in granulosa cells of PCOS patients compared with normal samples. These results increase our understanding of PCOS and the identified genes may serve as candidate biomarkers to develop diagnostic and therapeutic tools.

Serum Proteome Changes in Healthy Subjects with Different Genotypes of NOS1AP in the Chinese Population

Type 2 diabetes and its chronic complications have become a worldwide epidemic nowadays. However, its molecular mechanism is still unknown. We have previously identified a novel variant rs12742393 of NOS1AP for type 2 diabetes susceptibility in the Chinese population. In this study, we analyzed the total serum profiling among three genotypes of rs12742393 to discover potential crosstalk under the variant and the disease through proteomic analyses for the first time. We used OFFGEL peptide fractionation, LC-MS/MS analysis, and label-free quantification to profile the fasting human serum samples of the genotypes in rs12742393 (n = 4, for CC, AC, and AA, resp.). Four proteins were identified, including apoA4, alpha1-ACT, HABP2, and keratin 10, with blood levels changed significantly between CC and AA homozygotes of rs12742393. Compared with AA group, the levels of apoA4 increased (P = 0.000265), whereas the concentration of alpha1-ACT, HABP2, and keratin 10 decreased in CC group (P = 0.011116, 0.021175, and 0.015661, resp.). Then we selected additional fasting serum samples for ELISA and western blot validation. However, no significant differences were identified by neither ELISA nor western blot (P > 0.05). The protein profiling changes between the genotypes of rs12742393 indicated that this SNP might play a role in the development of type 2 diabetes.

TheAPOA4Thr347→Ser347Polymorphism Is Not a Major Risk Factor of Obesity

OBJECTIVE

The goal of this study was to assess the association between the APOA4 Thr(347)-->Ser(347) polymorphism and BMI and obesity.

RESEARCH METHODS AND PROCEDURES

Men and women (n = 3320), randomly recruited in three independent population surveys from the north, east, and south of France, were genotyped for the APOA4 Thr(347)-->Ser(347) polymorphism.

RESULTS

There were 1327 overweight (825 men, 502 women) and 611 obese (313 men, 298 women) subjects. The prevalences of subjects carrying at least one Ser(347) allele (*/Ser(347)) were 36.5%, 33.8%, and 34.3% in controls, overweight, and obese subjects, respectively (not significant), and those of the Ser(347)/Ser(347) genotype were 4.5%, 3.0%, and 2.2%, respectively (not significant). In both men and women, mean BMI and body weight were not significantly different among APOA4 genotypes. There was no evidence of heterogeneity among centers, smoking status, alcohol intake, physical activity, and educational level categories. In men, mean waist girth was lower in Ser(347)/Ser(347) (92.2 +/- 9.4 cm) than in Thr(347) carriers (95.9 +/- 10.9 cm; p = 0.01), and plasma triglycerides levels were lower in Ser(347) (1.41 +/- 1.04 mM) than in Thr(347)/Thr(347) carriers (1.55 +/- 1.23 mM; p = 0.01).

DISCUSSION

These results suggest that the APOA4 347Ser allele is not a major risk factor for obesity or overweight.

Potential biomarkers in psychiatry: focus on the cholesterol system

Measuring biomarkers to identify and assess illness is a strategy growing in popularity and relevance. Although already in clinical use for treating and predicting cancer, no biological measurement is used clinically for any psychiatric disorder. Biomarkers could predict the course of a medical problem, and aid in determining how and when to treat. Several studies have indicated that of candidate psychiatric biomarkers detected using proteomic techniques, cholesterol and associated proteins, specifically apolipoproteins (Apos), may be of interest. Cholesterol is necessary for brain development and its synthesis continues at a lower rate in the adult brain. Apos are the protein component of lipoproteins responsible for lipid transport. There is extensive evidence that the levels of cholesterol and Apos may be disturbed in psychiatric disorders, including autistic spectrum disorders (ASD). Here, we describe putative serum biomarkers for psychiatric disorders, and the role of cholesterol and Apos in central nervous system (CNS) disorders.

Plasma proteomics shows an elevation of the anti-inflammatory protein APOA-IV in chronic equine laminitis

Background

Equine laminitis is a devastating disease that causes severe pain in afflicted horses and places a major economic burden on the horse industry. In acute laminitis, the disintegration of the dermal-epidermal junction can cause the third phalanx to detach from the hoof wall, leaving the horse unable to bear weight on the affected limbs. Horses that survive the acute phase transition into a chronic form of laminitis, which is often termed “founder”. Some evidence suggests that chronic laminar inflammation might be associated with alterations in the endocrine and immune systems. We investigated this broad hypothesis by using DIGE to assess global differences in the plasma proteome between horses with chronic laminitis and controls.

Results

We identified 16 differentially expressed proteins; the majority of these were involved in the interrelated coagulation, clotting, and kininogen cascades. Clinical testing of functional coagulation parameters in foundered horses revealed a slight delay in prothrombin (PT) clotting time, although most other indices were within normal ranges. Upregulation of the intestinal apolipoprotein APOA-IV in horses with chronic laminitis was confirmed by western blot.

Conclusions

Our results support the hypothesis that localized laminar inflammation may be linked to systemic alterations in immune regulation, particularly in the gastrointestinal system. Gastrointestinal inflammation has been implicated in the development of acute laminitis but has not previously been associated with chronic laminitis.

The structure of dimeric apolipoprotein A-IV and its mechanism of self-association

Apolipoproteins are key structural elements of lipoproteins and critical mediators of lipid metabolism. Their detergent-like properties allow them to emulsify lipid or exist in a soluble lipid-free form in various states of self-association. Unfortunately, these traits have hampered high-resolution structural studies needed to understand the biogenesis of cardioprotective high-density lipoproteins (HDLs). We derived a crystal structure of the core domain of human apolipoprotein (apo)A-IV, an HDL component and important mediator of lipid absorption. The structure at 2.4 Å depicts two linearly connected 4-helix bundles participating in a helix swapping arrangement that offers a clear explanation for how the protein self-associates as well as clues to the structure of its monomeric form. This also provides a logical basis for antiparallel arrangements recently described for lipid-containing particles. Furthermore, we propose a "swinging door" model for apoA-IV lipid association.

Noticeable decreased expression of tenascin-X in calcific aortic valves

Calcification of aortic valves results in valvular aortic stenosis and is becoming a common valvular condition in elderly populations. An understanding of the molecular mechanisms of this valve lesion is important for revealing potential biomarkers associated with the development and progression of this disease. In order to identify proteins that are differentially expressed in calcific aortic valves (CAVs) compared with those in adjacent normal valvular tissues, comprehensive analysis of differentially expressed proteins in the tissues was done by a quantitative proteomic approach with isobaric tag for absolute and relative quantitation labeling followed by nanoliquid chromatography matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry. The proteomic analysis revealed 105 proteins differentially expressed in CAVs in contrast to adjacent normal valvular tissues with high confidence. Significantly increased expression (≥1.3-fold) was found in 34 proteins, whereas decreased expression (<0.77-fold) was found in 39 proteins in CAVs. Among them, α-2-HS-glycoprotein showed the greatest increase in expression (6.54-fold) and tenascin-X showed the greatest decrease in expression (0.37-fold). Numerous extracellular matrix proteins such as collagens were identified as proteins with significantly decreased expression. Panther pathway analysis showed that some of the identified proteins were linked to blood coagulation and integrin signaling pathways. Cluster analysis of the 105 proteins differentially expressed in CAVs based on the expression pattern revealed that tenascin-X was clustered with proteins controlling collagen structure and function, especially collagen fibrillogenesis, such as decorin and fibromodulin. We confirmed decreased levels of these proteins in CAVs by Western blot analyses. These results indicated that massive destruction of the extracellular matrix occurs in CAVs.

Apolipoprotein A-IV improves glucose homeostasis by enhancing insulin secretion

Apolipoprotein A-IV (apoA-IV) is secreted by the small intestine in response to fat absorption. Here we demonstrate a potential role for apoA-IV in regulating glucose homeostasis. ApoA-IV-treated isolated pancreatic islets had enhanced insulin secretion under conditions of high glucose but not of low glucose, suggesting a direct effect of apoA-IV to enhance glucose-stimulated insulin release. This enhancement involves cAMP at a level distal to Ca(2+) influx into the β cells. Knockout of apoA-IV results in compromised insulin secretion and impaired glucose tolerance compared with WT mice. Challenging apoA-IV(-/-) mice with a high-fat diet led to fasting hyperglycemia and more severe glucose intolerance associated with defective insulin secretion than occurred in WT mice. Administration of exogenous apoA-IV to apoA-IV(-/-) mice improved glucose tolerance by enhancing insulin secretion in mice fed either chow or a high-fat diet. Finally, we demonstrate that exogenous apoA-IV injection decreases blood glucose levels and stimulates a transient increase in insulin secretion in KKAy diabetic mice. These results suggest that apoA-IV may provide a therapeutic target for the regulation of glucose-stimulated insulin secretion and treatment of diabetes.

ApoA-IV modulates the secretory trafficking of apoB and the size of triglyceride-rich lipoproteins

Although the evidence linking apoA-IV expression and triglyceride (TG)-rich lipoprotein assembly and secretion is compelling, the intracellular mechanisms by which apoA-IV could modulate these processes remain poorly understood. We therefore examined the functional impact of apoA-IV expression on endogenous apoB, TG, and VLDL secretion in stably transfected McA-RH7777 rat hepatoma cells. Expression of apoA-IV modified with the endoplasmic reticulum (ER) retention signal KDEL (apoA-IV-KDEL) dramatically decreased both the rate and efficiency of endogenous apoB secretion, suggesting a presecretory interaction between apoA-IV-KDEL and apoB or apoB-containing lipoproteins. Expression of native apoA-IV using either a constitutive or tetracycline-inducible promoter delayed the initial rate of apoB secretion and reduced the final secretion efficiency by ∼40%. However, whereas apoA-IV-KDEL reduced TG secretion by 75%, expression of native apoA-IV caused a 20-35% increase in TG secretion, accompanied by a ∼55% increase in VLDL-associated apoB, an increase in the TG:phospholipid ratio of secreted d < 1.006 lipoproteins, and a 10.1 nm increase in peak VLDL(1) particle diameter. Native apoA-IV expression had a negligible impact on expression of the MTP gene. These data suggest that by interacting with apoB in the secretory pathway, apoA-IV alters the trafficking kinetics of apoB-containing TG-rich lipoproteins through cellular lipidation compartments, which in turn, enhances particle expansion and increases TG secretion.

Transcriptomic analyses of intestinal gene expression of juvenile Atlantic cod (Gadus morhua) fed diets with Camelina oil as replacement for fish oil

For aquaculture of marine species to continue to expand, dietary fish oil (FO) must be replaced with more sustainable vegetable oil (VO) alternatives. Most VO are rich in n-6 polyunsaturated fatty acids (PUFA) and few are rich in n-3 PUFA but Camelina oil (CO) is unique in that, besides high 18:3n-3 and n-3/n-6 PUFA ratio, it also contains substantial long-chain monoenes, commonly found in FO. Cod (initial mass ~1.4 g) were fed for 12 weeks diets in which FO was replaced with CO. Growth performance, feed efficiency and biometric indices were not affected but lipid levels in liver and intestine tended to increase and those of flesh, decrease, with increasing dietary CO although only significantly for intestine. Reflecting diet, tissue n-3 long-chain PUFA levels decreased whereas 18:3n-3 and 18:2n-6 increased with inclusion of dietary CO. Dietary replacement of FO by CO did not induce major metabolic changes in intestine, but affected genes with potential to alter cellular proliferation and death as well as change structural properties of intestinal muscle. Although the biological effects of these changes are unclear, given the important role of intestine in nutrient absorption and health, further attention should be given to this organ in future.

Intestinal gene expression in pigs: effects of reduced feed intake during weaning and potential impact of dietary components

The weaning transition is characterised by morphological, histological and microbial changes, often leading to weaning-associated disorders. These intestinal changes can partly be ascribed to the lack of luminal nutrition arising from the reduced feed intake common in pigs after weaning. It is increasingly becoming clear that changes in the supply with enteral nutrients may have major impacts on intestinal gene expression. Furthermore, the major dietary constituents, i.e. carbohydrates, fatty acids and amino acids, participate in the regulation of intestinal gene expression. However, nutrients may also escape digestion by mammalian enzymes in the upper gastrointestinal tract. These nutrients can be used by the microflora, resulting in the production of bacterial metabolites, for example, SCFA, which may affect intestinal gene expression indirectly. The present review provides an insight on possible effects of reduced feed intake on intestinal gene expression, as it may occur post-weaning. Detailed knowledge on effects of reduced feed intake on intestinal gene expression may help to understand weaning-associated intestinal dysfunctions and diseases. Examples are given of intestinal genes which may be altered in their expression due to supply with specific nutrients. In that way, gene expression could be modulated by dietary means, thereby acting as a potential therapeutic tool. This could be achieved, for example, by influencing genes coding for digestive or absorptive proteins, thus optimising digestive function and metabolism, but also with regard to immune response, or by influencing proliferative processes, thereby enhancing mucosal repair. This would be of special interest when designing a diet to overcome weaning-associated problems.

Impact of murine intestinal apolipoprotein A-IV expression on regional lipid absorption, gene expression, and growth

Apolipoprotein A-IV (apoA-IV) is synthesized by intestinal enterocytes during lipid absorption and secreted into lymph on the surface of nascent chylomicrons. A compelling body of evidence supports a central role of apoA-IV in facilitating intestinal lipid absorption and in regulating satiety, yet a longstanding conundrum is that no abnormalities in fat absorption, feeding behavior, or weight gain were observed in chow-fed apoA-IV knockout (A4KO) mice. Herein we reevaluated the impact of apoA-IV expression in C57BL6 and A4KO mice fed a high-fat diet. Fat balance and lymph cannulation studies found no effect of intestinal apoA-IV gene expression on the efficiency of fatty acid absorption, but gut sac transport studies revealed that apoA-IV differentially modulates lipid transport and the number and size of secreted triglyceride-rich lipoproteins in different anatomic regions of the small bowel. ApoA-IV gene deletion increased expression of other genes involved in chylomicron assembly, impaired the ability of A4KO mice to gain weight and increase adipose tissue mass, and increased the distal gut hormone response to a high-fat diet. Together these findings suggest that apoA-IV may play a unique role in integrating feeding behavior, intestinal lipid absorption, and energy storage.

The development and endocrine functions of adipose tissue

White adipose tissue is a mesenchymal tissue that begins developing in the fetus. Classically known for storing the body's fuel reserves, adipose tissue is now recognized as an endocrine organ. As such, the secretions from adipose tissue are known to affect several systems such as the vascular and immune systems and play major roles in metabolism. Numerous studies have shown nutrient or hormonal manipulations can greatly influence adipose tissue development. In addition, the associations between various disease states, such as insulin resistance and cardiovascular disease, and disregulation of adipose tissue seen in epidemiological and intervention studies are great. Evaluation of known adipokines suggests these factors secreted from adipose tissue play roles in several pathologies. As the identification of more adipokines and determination of their role in biological systems, and the interactions between adipocytes and other cells types continues, there is little doubt that we will gain a greater appreciation for a tissue once thought to simply store excess energy.

Localized expression of genes related to carbohydrate and lipid absorption along the crypt-villus axis of rat jejunum

BACKGROUND

Enterocytes of the jejunum express several genes related to digestion/absorption of nutrients and ions when these cells rapidly differentiate from crypt to villus cells. However, it is unknown whether the distribution of extensive gene expression along the villus-crypt axis of the jejunum is altered during differentiation.

METHODS

We investigated the changes in jejunal gene expression during differentiation from crypt to villus cells in rats using DNA microarray analysis on cryostat sections of the villus-crypt columns.

RESULTS

During differentiation, the expression of many genes related to cell growth rapidly decreased, while expression of genes related to digestion and absorption of nutrients and ions increased. Expression of a subset of genes related to the digestion and absorption of starch and sucrose was highest at the middle of the villi, whereas expression of genes related to dietary fat absorption was highest at the top of the villi. Several transcriptional factors such as Pdx1, Foxa2 and Thra were expressed in the crypt, whereas Klf15 was highly expressed during the crypt-villus transition. Expression of Klf4 and Pparg was highest at the top of the villi.

CONCLUSIONS

Subsets of genes related to the digestion and absorption of starch/sucrose and dietary fat as well as their transcriptional factors/co-factors are expressed in the specific locations along the crypt-villus axis.

GENERAL SIGNIFICANCE

The jejunum may absorb nutrients effectively by simultaneously expressing subsets of genes along the villus-crypt axis.

Plasma proteome analysis for anti-obesity and anti-diabetic potentials of chitosan oligosaccharides in ob/ob mice

Altered levels of adipokines, derived as a result of distorted adipocytes, are the major factors responsible for changing biochemical parameters in obesity that leads to the development of metabolic disorders such as insulin resistance and atherosclerosis. In our previous reports, chitosan oligosaccharides (CO) were proved to inhibit the differentiation of 3T3-L1 adipocytes. In the present study, an attempt was made to investigate the anti-obesity and anti-diabetic effect of CO on ob/ob mice, by means of differential proteomic analysis of plasma. This was followed by immunoblotting, and gene expression in adipose tissue to clarify the molecular mechanism. CO treatment showed reduced diet intake (13%), body weight gain (12%), lipid (29%) and glucose levels (35%). 2-DE results showed differential levels of five proteins namely RBP4, apoE, and apoA-IV by >2-fold down-regulation and by >2-fold of apoA-I and glutathione peroxidase (GPx) up-regulation after CO treatment. Immunoblotting studies of adiponectin and resistin showed amelioration in their levels in plasma. Furthermore, the results of gene expressions for adipose tissue specific TNF-alpha, and IL-6 secretary molecules were also down-regulated by CO treatment. Gene expressions of PPAR gamma in adipose tissue were in good agreement with the ameliorated levels of adipokines, thereby improving the pathological state. Taken together, CO might act as a potent down-regulator of obesity-related gene expression in ob/ob mice that may normalize altered plasma proteins to overcome metabolic disorders of obesity.

Hepatocyte nuclear factor 4alpha contributes to an intestinal epithelial phenotype in vitro and plays a partial role in mouse intestinal epithelium differentiation

Hepatocyte nuclear factor 4alpha (HNF4alpha) is a regulator of hepatocyte and pancreatic transcription. Hnf4alpha deletion in the mouse is embryonically lethal with severe defects in visceral endoderm formation. It has been concluded in the past that the role of Hnf4alpha in the developing colon was much less important than in the liver. However, the precise role of Hnf4alpha in the homeostasis of the small intestinal epithelium remains unclear. Our aim was to evaluate the potential of Hnf4alpha to support an intestinal epithelial phenotype. First, Hnf4alpha potential to dictate this phenotype was assessed in nonintestinal cell lines in vitro. Forced expression of Hnf4alpha in fibroblasts showed an induction of features normally restricted to epithelial cells. Combinatory expression of Hnf4alpha with specific transcriptional regulators of the intestine resulted in the induction of intestinal epithelial genes in this context. Second, the importance of Hnf4alpha in maintaining the homeostasis of the intestinal epithelium was investigated in mice. Mice conditionally deficient for intestinal Hnf4alpha developed normally throughout adulthood with an epithelium displaying normal morphological and functional structures with minor alterations. Subtle but statistical differences were observed at the proliferation and the cytodifferentiation levels. Hnf4alpha mutant mice displayed an increase in the number of goblet and enteroendocrine cells compared with controls. Given the fundamental role of this transcription factor in other tissues, these findings dispute the crucial role for this regulator in the maintenance of intestinal epithelial cell function at a period of time that follows cytodifferentiation but may suggest a functional role in instructing cells to become specific to the intestinal epithelium.

Activation of PXR induces hypercholesterolemia in wild-type and accelerates atherosclerosis in apoE deficient mice

The nuclear hormone receptor pregnane X receptor (PXR; also called SXR) functions as a xenobiotic sensor to coordinately regulate xenobiotic metabolism via transcriptional regulation of xenobiotic-detoxifying enzymes and transporters. Although many clinically relevant PXR ligands have been shown to affect cholesterol levels, the role of PXR in cholesterol homeostasis and atherosclerosis has not been thoroughly investigated. Here, we report that activation of PXR by feeding the PXR agonist pregnenolone 16alpha-carbonitrile (0.02%) for 2 weeks to wild-type (WT) mice significantly increased total cholesterol levels and atherogenic lipoproteins VLDL and LDL levels, but had no effect in PXR knockout (PXR(-/-)) mice. Chronic PXR activation in atherosclerosis prone apolipoprotein E deficient (ApoE(-/-)) mice was found to decrease HDL levels and increase atherosclerotic cross-sectional lesion area at both the aortic root and in the brachiocephalic artery by 54% (P < 0.001) and 116% (P < 0.01), respectively. PXR activation significantly regulated genes in the liver involved in lipoprotein transportation and cholesterol metabolism, including CD36, ApoA-IV, and CYP39A1, in both WT and ApoE(-/-) mice. Furthermore, PXR activation can increase CD36 expression and lipid accumulation in peritoneal macrophages of ApoE(-/-) mice. In summary, PXR activation in WT mice increases levels of the atherogenic lipoproteins VLDL and LDL, whereas in ApoE(-/-) mice, PXR increases atherosclerosis, perhaps by diminishing levels of the antiatherogenic ApoA-IV and increasing lipid accumulation in macrophages.

Afamin and apolipoprotein A-IV: novel protein markers for ovarian cancer

Comparative proteomics identified the vitamin E-binding plasma protein afamin as a potential novel tumor marker for ovarian cancer. In addition, we observed in a previous small study decreased plasma concentrations of apolipoprotein A-IV (apoA-IV) in preoperative patients with kidney cancer. The aim of this study was therefore to analyze afamin and apoA-IV in a large case-control study to evaluate the diagnostic utility of the two potential novel tumor markers in ovarian cancer patients. We measured plasma concentrations of afamin and apoA-IV by means of a specific sandwich-type ELISA using affinity-purified polyclonal and monoclonal antibodies in 181 ovarian cancer patients of various clinical stages, 399 patients with benign gynecologic diseases, including endometriosis, and 177 controls and compared results with those for the conventional ovarian cancer tumor marker cancer antigen 125 (CA125). Afamin concentrations decreased from a median of 70.7 mg/L (range, 34.6-116.1 mg/L) in healthy controls to 65.2 mg/L (range, 20.2-206.6 mg/L) in patients with benign gynecologic diseases to 56.0 mg/L (range, 4.7-96.0 mg/L) in ovarian cancer patients (P < 0.001 for all pairwise comparisons). Similar results were obtained with apoA-IV concentrations decreasing from 13.0 mg/dL (range, 5.5-34.0 mg/dL) in controls to 11.7 mg/dL (range, 2.0-32.3 mg/dL) in benign conditions to 9.4 mg/dL (range, 0.3-29.5 mg/dL) in ovarian cancer (all P < 0.001). Receiver operating characteristic analysis for differentiating ovarian cancer patients from healthy controls revealed for a specificity of 90% sensitivity values of 92.4%, 42.4%, and 40.8% for CA125, afamin, and apoA-IV, respectively. Afamin, but not apoA-IV, added independent diagnostic information to CA125 and age for differentiating ovarian cancer from benign and healthy samples; the odds ratio of ovarian cancer was reduced by 44% for each doubling of afamin (P = 0.032). The relatively low sensitivity, however, clearly indicates that afamin and apoA-IV alone are not sufficiently suitable as diagnostic markers for ovarian cancer. Afamin contributes, however, independent diagnostic information to CA125, thus establishing its potential as an adjunct marker to CA125.

The effect of trans-10, cis-12 conjugated linoleic acid on gene expression profiles related to lipid metabolism in human intestinal-like Caco-2 cells

We conducted an in-depth investigation of the effects of conjugated linoleic acid (CLA) on the expression of key metabolic genes and genes of known importance in intestinal lipid metabolism using the Caco-2 cell model. Cells were treated with 80 mumol/L of linoleic acid (control), trans-10, cis-12 CLA or cis-9, trans-11 CLA. RNA was isolated from the cells, labelled and hybridized to the Affymetrix U133 2.0 Plus arrays (n = 3). Data and functional analysis were preformed using Bioconductor. Gene ontology analysis (GO) revealed a significant enrichment (P < 0.0001) for the GO term lipid metabolism with genes up-regulated by trans-10, cis-12 CLA. Trans-10, cis-12 CLA, but not cis-9, trans-11 CLA, altered the expression of a number of genes involved in lipid transport, fatty acid metabolism, lipolysis, beta-oxidation, steroid metabolism, cholesterol biosynthesis, membrane lipid metabolism, gluconeogenesis and the citrate cycle. These observations warrant further investigation to understand their potential role in the metabolic syndrome.