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Myeloperoxidase (MPO) is a unique heme-containing peroxidase that can catalyze the formation of hypochlorous acid (HOCl). The strong interaction of MPO with low-density lipoproteins (LDL) promotes proatherogenic modification of LDL by HOCl. The MPO-modified LDL (Mox-LDL) accumulate in macrophages, resulting in the formation of foam cells, which is the pathognomonic symptom of atherosclerosis. A promising approach to prophylaxis and atherosclerosis therapy is searching for remedies that prevent the modification or accumulation of LDL in macrophages. Lactoferrin (LF) has several application points in obesity pathogenesis. We aimed to study LF binding to Mox-LDL and their accumulation in monocytes transformed into macrophages. Using surface plasmon resonance and ELISA techniques, we observed no LF interaction with intact LDL, whereas Mox-LDL strongly interacted with LF. The affinity of Mox-LDL to LF increased with the degree of oxidative modification of LDL. Moreover, an excess of MPO did not prevent interaction of Mox-LDL with LF. LF inhibits accumulation of cholesterol in macrophages exposed to Mox-LDL. The results obtained reinforce the notion of LF potency as a remedy against atherosclerosis. Key words: lactoferrin, low-density lipoproteins, myeloperoxidase, halogenative stress, cholesterol, atherosclerosis. La myeloperoxydase (MPO) est une peroxydase unique a heme qui peut catalyser la formation d'acide hypochloreux (HOCl). La forte interaction entre la MPO et les proteines de faible densite (LDL) favorise la modification proatherogene des LDL par le HOCl. Les LDL modifiees par la MPO (Mox-LDL) s'accumulent dans les macrophages donnant lieu a la formation de cellules spumeuses, ce qui est le symptome pathognomonique de l'atherosclerose. Une approche prometteuse de prophylaxie et de therapie de l'atherosclerose consiste a rechercher des remedes qui previennent la modification ou l'accumulation des LDL dans les macrophages. La lactoferrine (LF) offre plusieurs points d'intervention dans la pathogenese de l'obesite. Les auteurs avaient pour objectif d'etudier la liaison de la LF aux Mox-LDL et leur accumulation dans les monocytes transformes en macrophages. Ils n'ont observe aucune interaction entre la LF et les LDL intacts par resonance plasmonique de surface et ELISA, contrairement aux Mox-LDL qui interagissaient fortement avec la LF. L'affinite des Mox-LDL pour la LF augmentait avec le degre de modification oxydative des LDL. Qui plus est, un exces de MPO ne prevenait pas l'interaction entre les Mox-LDL et la LF. La LF inhibe l'accumulation de cholesterol dans les macrophages exposes aux Mox-LDL. Les resultats obtenus renforcent la notion de la capacite de la LF d'agir comme remede contre l'atherosclerose. [Traduit par la Redaction] Mots-cles : lactoferrine, lipoproteines de faible densite, myeloperoxydase, stress halogenant, cholesterol, atherosclerose., Introduction The role of immunologic factors in atherogenesis has been studied extensively in recent years. Atherosclerosis is now regarded as chronic immune inflammation. Meanwhile, the key role of excessive amounts [...]

Abstract: Cholesterol plays an important role in determining the biophysical properties of membranes in mammalian cells, and the concentration of cholesterol in membranes is tightly regulated. Cholesterol moves among membrane [...]

Abstract: Glycation of apolipoproteins is a major feature of the production of dysfunctional high-density lipoprotein (HDL), which is associated with the incidence of several metabolic diseases such as coronary artery [...]

In-vitro studies were performed to shed light on previous findings that showed increased uptake of cyclosporine A in the kidneys and liver of hyperlipidemic rats, and increased signs of kidney toxicity. Hepatocytes were obtained from rats, cultured, and exposed to a diluted serum from hyperlipidemic rats. Some cells were also exposed to lipid-lowering drugs. After washing out the rat serum or lipid-lowering drugs, cells were exposed to cyclosporine A embedded in serum lipoproteins. Pretreatment with hyperlipidemic serum and lipid-lowering drugs was associated with an increased uptake of cyclosporine A. As expected, atorvastatin caused an increase in low density lipoprotein receptor and a decrease in MDR1A mRNA in the hepatocytes. A decrease in NRK-52E rat renal tubular cellular viability caused by cyclosporine A was noted when cells were preincubated with diluted hyperlipidemic serum. This was matched with evidence of hyperlipidemic-serum-associated increases in the NRK-52E cellular uptake of cyclosporine A and rhodamine-123. The findings of these experiments suggested that in hyperlipidemia the expression and (or) the functional activity of P-glycoprotein was diminished, leading to greater hepatic and renal uptake of cyclosporine A, and renal cellular toxicity. Key words: hepatocytes, hyperlipidemia, lipoprotein receptors, NRK-52E cells, P-glycoprotein. Des etudes in vitro ont ete realisees afin de faire la lumiere sur des resultats obtenus precedemment, qui ont revele une captation accrue de cyclosporine A dans les reins et le foie de rats hyperlipidemiques ainsi que des signes accrus de toxicite renale. Des hepatocytes de rats ont ete isoles, cultives et exposes a du serum de rat hyperlipidemique dilue. Certaines cellules ont aussi ete exposees a des hypolipidemiants. Apres avoir rince les cellules du serum de rat ou des hypolipidemiants, elles ont ete exposees a la cyclosporine A enrobee dans des lipoproteines seriques. Le pretraitement au serum hyperlipidemique et aux hypolipidemiants etait associe a une captation accrue de cyclosporine A. Comme attendu, l'atorvastatine induisait une augmentation de l'expression du recepteur des lipoproteines de faible densite ainsi qu'une diminution de l'expression de l'ARNm de MDR1A dans les hepatocytes. Une diminution la viabilite des cellules de tubules renaux de rats NRK-52E induite par la cyclosporine A a ete notee lorsque les cellules etaient preincubees avec le serum hyperlipidemique dilue. Cela coincidait avec l'augmentation de la captation de cyclosporine A et de rhodamine-123 associee au serum hyperlipidemique dans les cellules NRK-52E. Les resultats de ces experiences suggerent qu'en situation d'hyperlipidemie, l'expression et (ou) l'activite fonctionnelle de la P-glycoproteine etait diminuee, conduisant a une captation accrue de clyclosporine A par le foie et les reins, ainsi qu'a une toxicite cellulaire renale. [Traduit par la Redaction] Mots-cles: hepatocytes, hyperlipidemie, recepteurs de lipoproteines, cellules NRK-52E, P-glycoproteine., Introduction In rats, experimental hyperlipidemia (HL) is associated with increased concentrations of the immunosuppressive agent, cyclosporine A (CyA) in the kidneys and liver (Aliabadi et al. 2006). This finding has [...]

Myeloperoxidase (MPO) and paraoxonase 1 (PON1) are high-density lipoprotein--associated (HDL-associated) proteins mechanistically linked to inflammation, oxidant stress, and atherosclerosis. MPO is a source of ROS during inflammation and can oxidize [...]

The effects of repeated administration of poloxamer 407 (P-407) on lipoprotein-cholesterol (LP-C) and lipoprotein-triglyceride (LP-TG) fractions and subtractions, as well as the effect on liver and heart proteases, were studied. Repeated administration of P-407 to male CBA mice resulted in a model of atherosclerosis with increased diastolic blood pressure; there was a drastic increase in total serum cholesterol and especially TG. A novel small-angle X-ray scattering method for the determination of the fractional and subfractional composition of LP-C and LP-TG was used. In chronically P-107-treated mice, P-107 significantly increased atherogenic low-density lipoprotein C (LDL-C) fractions, as well as intermediate-density lipoprotein C (IDL-C), and [LDL.sub.1-3]-C subfractions, and very-low-density lipoprotein-C (VLDL-C) fractions, as well as [VLDL.sub.1-2-C] and [VLDL.sub.3-5]-C subfractions), to a lesser extent, the total anti-atherogenic high-density lipoprotein C (HDL-C) fraction, as well as [HDL.sub.2]-C and [HDL.sub.3]-C subfractions. Additionally, we demonstrated an increase in the serum chitotriosidase activity, without significant changes in serum matrix metalloprotease (MMP) activity. Morphological changes observed in P-407-treated mice included atherosclerosis in the heart and storage syndrome in the liver macrophages. P-407 significantly increased the activity of cysteine, aspartate proteases, and MMPs in the heart, and only the activity of cathepsin B and MMPs in the liver of mice. Thus, repeated administration of P4-07 to mice induced atherosclerosis secondary to sustained dyslipidemia and formation of foamy macrophages in liver, and also modulated the activity of heart and liver proteases. Key words: lipoprotein fractions and subfractions, P-407-induced heart and liver injury, cathepsins B, L, and D, matrix metalloproteases, chitotriosidase. L'effet d'une administration repetee de poloxamer 407 (P-407) sur les fractions et les sous-fractions de lipoproteines-cholesterol (LP-C) et de lipoproteines-triglycerides (LP-TG) ainsi que son effet sur les proteases du foie et du coeur ont ete etudies. L'administration repetee de P-107 chez les souris produisait un modele d'atherosclerose caracterise par une pression sanguine diastolique accrue ; on observait une augmentation radicale du cholesterol total serique et particulierement des TG. Une nouvelle methode de dispersion de rayons-X a angle reduit a ete utilisee pour determiner la composition des fractions et des sous-fractions de LP-C et LP-TG. Lorsqu'administre de facon chronique a des souris, le P-107 augmentait significativement les lipoproteines de faible densite C (LDL-C) atherogenes (sous-fractions lipoproteines de densite intermediaire (IDL-C et [LDL.sub.1-3]-C) et les lipoproteines de tres faible densite-C (VLDL-C) (sous-fractions [VLDL.sub.1-2]-C et [VLDL.sub.3-5]-C) et, dans une moindre mesure, la fraction totale anti-atherogene des lipoproteines de haute densite (HDL-C: sous fractions [HDL.sub.2]-C et [HDL.sub.3]-C). De plus, une augmentation de Factivite chitotriosidase serique etait demontree, alors que l'activite metalloprotease de la matrice (MMP) du serum ne changeait pas significativement. Les changements morphologiques observes chez les souris traitees au P-407 incluaient l'atherosclerose du coeur et le syndrome de stockage des macrophages du foie. Le P4-07 augmentait significativement Factivite des proteases a cysteine, des proteases a aspartate et des MMP dans le coeur, et Factivite de la cathepsine B et des MMP seulement, dans le foie des souris. Ainsi, l'administration repetee de P-407 chez les souris induisait une atherosclerose secondaire a une dyslipemie prolongee et a la formation de macrophages spumeux dans le foie, ainsi qu'une modulation de l'activite des proteases du cour et du foie. Mots-cles : fractions et sous-fractions de lipoproteines, dommage cardiaque et hepatique induit par le P-407, cathepsines B, L et D, metalloproteases de la matrice, chitotriosidase. [Traduit par la Redaction], Introduction Recently, using a novel small-angle X-ray scattering (SAXS) method for the determination of fractional and subfractional composition of lipoproteins (LPs), we showed that a high dose of atorvastatin exerts [...]

Lipoprotein-associated cholesterol has been suggested to make a significant contribution to adrenal steroidogenesis in vivo. To determine whether lipoproteins indeed contribute to optimal adrenal steroidogenesis in mice, in the current study we have determined the effect of relative lipoprotein deficiency on adrenal steroidogenesis in C57BL/6 wild-type mice. Feeding C57BL/6 mice the lipid-lowering drug probucol (0.25% wt/wt) for 2 wk induced a 90% decrease in plasma high-density lipoprotein (HDL) cholesterol levels and a 77% reduction in low-density lipoprotein (LDL) cholesterol levels. Neutral lipid stores were depleted upon probucol treatment specifically in the glucocorticoid-producing zona fasciculata of the adrenal, leading to a 44% decreased plasma corticosterone level under basal conditions. Exposure to lipopolysaccharide (LPS) induced a 37% increase in the adrenal uptake of HDL cholesteryl esters. Probucol-treated mice could induce only a relatively minor corticosterone response upon a LPS challenge compared with controls, which coincided with an approximately twofold increased hepatic expression level of interleukin-6 and tumor necrosis factor (TNF)[alpha] and an 89% higher TNF[alpha] response in plasma. Furthermore, a compensatory two- to fivefold upregulation of LDL receptor (cholesterol uptake) and HMG-CoA reductase (cholesterol synthesis) expression was noticed in the adrenals of probucol-treated mice. In conclusion, we have shown that lipoprotein deficiency in mice as a result of probucol feeding is associated with decreased adrenal cortex cholesterol levels, a lower basal and stress-induced plasma glucocorticoid level, and an increased susceptibility to LPS-induced inflammation. Therefore, it is suggested that plasma lipoproteins are required for optimal adrenal steroidogenesis and protection against endotoxemia in mice. probucol; scavenger receptor BI; low-density lipoprotein receptor; hydroxylmethylglutaryl-coenzyme A reductase; lipopolysaccharide doi: 10.1152/ajpendo.00431.2010.

Obesity and type 2 diabetes are associated with insulin resistance (IR), increased circulating proinflammatory cytokines, and hypertriglyceridemia, the latter being caused by overproduction of hepatic very low density lipoprotein (VLDL). One cytokine strongly linked with development of hepatic IR is interleukin-6 (IL-6). Our objective was to evaluate IL-6 effects on hepatic apolipoprotein B (apoB) and VLDL secretion and to examine possible linkages between cytokine signaling and insulin-suppressive effects on lipoprotein secretion. Of the cytokines examined, only IL-6 stimulated secretion of apoB-containing lipoproteins in a dose-dependent manner. Both B100 and B48 secretion were significantly increased in VLDL and in lipoproteins with a density > 1.019 g/ml. The ability of insulin to suppress hepatic apoB secretion was maintained in hepatocytes treated with IL-6. Pulse-chase studies indicated that enhanced apoB synthesis was the primary mechanism for increased lipoprotein secretion, which corresponded with higher abundance of apoB mRNA. Because IL-6 did not alter the decay rate of apoB mRNA transcripts, results support that increased apoB mRNA levels are the result of enhanced apob gene transcription. Increased apoB-lipoprotein secretion was also detected with oncostatin M (OSM), supporting involvement of the signal-transducing protein, gpl30. Increased suppressor of cytokine signaling (SOCS) 3 expression negated IL-6 and OSM effects and significantly reduced cellular apoB mRNA abundance. We conclude that IL-6 favors secretion of apoB-containing lipoproteins by increasing availability of apoB through changes in apob gene transcription. These changes may contribute to hypersecretion of VLDL associated with obesity, particularly under conditions where SOCS3 is not overexpressed to an extent capable of overcoming IL-6-stimulated apob gene transcription. interleukin-6; suppressor of cytokine signaling 3 and hepatocyte lipoprotein secretion; very low density lipoprotein doi: 10.1152/ajpgi.00080.2010.

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen able to cause acute or chronic infections. Like all other Pseudomonas species, P. aeruginosa has a large genome, >6 Mb, encoding more than 5000 proteins. Many proteins are localized in membranes, among them lipoproteins, which can be found tethered to the inner or the outer membrane. Lipoproteins are translocated from the cytoplasm and their N-terminal signal peptide is cleaved by the signal peptidase II, which recognizes a specific sequence called the lipobox just before the first cysteine of the mature lipoprotein. A majority of lipoproteins are transported to the outer membrane via the LolCDEAB system, while those having an avoidance signal remain in the inner membrane. In Escherichia coil, the presence of an aspartate residue after the cysteine is sufficient to cause the lipoprotein to remain in the inner membrane, while in P. aeruginosa the situation is more complex and involves amino acids at position +3 and +4 after the cysteine. Previous studies indicated that there are 185 lipoproteins in P. aeruginosa, with a minority in the inner membrane. A reanalysis led to a reduction of this number to 175, while new retention signals could be predicted, increasing the percentage of inner-membrane lipoproteins to 20 %. About one-third (62 out of 175) of the lipoprotein genes are present in the 17 Pseudomonas genomes sequenced, meaning that these genes are part of the core genome of the genus. Lipoproteins can be classified into families, including those outer-membrane proteins having a structural role or involved in efflux of antibiotics. Comparison of various microarray data indicates that exposure to epithelial cells or some antibiotics, or conversion to mucoidy, has a major influence on the expression of lipoprotein genes in P. aeruginosa. DOI 10.1099/mic.0.040659-0

Bacterial infection and sepsis are associated with renal tubule dysfunction and dysregulation of systemic electrolyte balance but the underlying mechanisms are incompletely understood. Recently, we demonstrated that HC[O.sup.-.sub.3] absorption by the medullary thick ascending limb (MTAL) is inhibited by gram-negative bacterial LPS through activation of Toll-like receptor 4 (TLR4). Here, we examined whether MTAL transport is altered by activation of TLR2, the receptor predominantly responsible for recognizing gram-positive bacteria. Confocal immunofluorescence showed expression of TLR2 in the basolateral membrane domain of rat and mouse MTALs. The functional role of TLR2 was examined in perfused MTALs using [Pam.sub.3][CSK.sub.4], a bacterial lipoprotein analog that specifically activates TLR2. Adding [Pam.sub.3][CSK.sub.4] to the bath decreased HC[O.sup.-.sub.3] absorption by 25%. The inhibition by [Pam.sub.3][CSK.sub.4] was eliminated in MTALs from [TLR2.sup.-/-] mice. HC[O.sup.-.sub.3] absorption was also inhibited by the TLR2 agonists lipoteichoic acid and peptidoglycan, two cell wall components of gram-positive bacteria. The MEK/ERK inhibitor U0126 eliminated inhibition of HC[O.sup.-.sub.3] absorption by bath LPS but had no effect on inhibition by [Pam.sub.3][CSK.sub.4]. The inhibition by [Pam.sub.3][CSK.sub.4] was eliminated by the protein kinase C inhibitors chelerythrine Cl and bisindolylmaleimide. Moreover, the inhibition by [Pam.sub.3][CSK.sub.4], lipoteichoic acid, and peptidoglycan was additive to inhibition by LPS. Thus, agonists of basolateral TLR2 and TLR4 inhibit HC[O.sup.-.sub.3] absorption independently through distinct signaling pathways. We conclude that bacterial components act directly through TLRs to modify the transport function of renal tubules. During polymicrobial sepsis, gram-positive bacterial molecules acting through TLR2 and gram-negative LPS acting through TLR4 can function through parallel signaling pathways to impair MTAL transport. The inhibition of luminal acidification may impair the ability of the kidneys to correct systemic acidosis that contributes to sepsis pathogenesis. acid-base transport; sepsis; kidney; LPS; gram-positive bacteria doi: 10.1152/ajprenal.00108.2010.

The excess accumulation of lipids in islets is thought to contribute to the development of diabetes in obesity by impairing [beta]-cell function. However, lipids also serve a nutrient function in islets, and fatty acids acutely increase insulin secretion. A better understanding of lipid metabolism in islets will shed light on complex effects of lipids on [beta]-cells. Adipose differentiation-related protein (ADFP) is localized on the surface of lipid droplets in a wide range of cells and plays an important role in intracellular lipid metabolism. We found that ADFP was highly expressed in murine [beta]-cells. Moreover. islet ADFP was increased in mice on a high-fat diet (3.5-fold of control) and after fasting (2.5-fold of control), revealing dynamic changes in ADFP in response to metabolic cues. ADFP expression was also increased by addition of fatty acids in human islets. The downregulation of ADFP in MIN6 cells by antisense oligonucleotide (ASO) suppressed the accumulation of triglycerides upon fatty acid loading (56% of control) along with a reduction in the mRNA levels of lipogenic genes such as diacylglycerol O-acyltransferase-2 and fatty acid synthase. Fatty acid uptake, oxidation, and lipolysis were also reduced by downregulation of ADFP. Moreover, the reduction of ADFP impaired the ability of palmitate to increase insulin secretion. These findings demonstrate that ADFP is important in regulation of lipid metabolism and insulin secretion in [beta]-cells. MIN6 cells; oleic acid; palmitic acid; high-fat diet; fasting doi: 10.1152/ajpendo.00646.2009.

The objectives of this study were 1) to determine whether selection toward less subcutaneous fat thickness at constant intramuscular fat content in pigs is related to tissue-specific changes in the expression of lipogenic enzymes acetyl-CoA carboxylase (ACC), stearoyl-CoA desaturase (SCD), and A% desaturase ([DELTA]6d); and 2) to investigate tissue specific distribution of the porcine ACC, SCD, and [DELTA]6d. The study was conducted on 20 purebred Duroc barrows. Ten animals were from a group selected for decreased subcutaneous fat thickness at constant intramuscular fat content (experimental group). The other 10 animals were from the unselected (control) group. Distribution of ACC, SCD, and [DELTA]6d was investigated in semimembranosus muscle (SM), subcutaneous adipose tissue (SA), liver (L), kidney (K), heart (H), diaphragm (D), rectus capitis muscle (RCM), and abdominal fat (AF). The enzyme expression was studied in 10 animals in the case of SM and SA and in 4 animals in the case of other tissues. The following expression pattern was established for ACC: SM [less than or equal to] H = K [less than or equal to] D< RCM < L < AF = SA, whereas the expression patterns for SCD and [DELTA]6d proteins were SM < H < RCM < D < L < K < AF = SA and RCM = SM = D < L [less than or equal to] H < SA < K < AF, respectively. Expression of ACC and SCD proteins was less in subcutaneous adipose tissue of the experimental animals when compared with the control group (P < 0.001). However, no difference (P > 0.1) in ACC and SCD protein expression between the control and experimental groups was observed in SM. Expression of [DELTA]6d protein did not differ between the control and experimental groups for SA (P = 0.47) or SM (P = 0.31). There was a positive relationship between muscle SCD protein expression and intramuscular fat content (r = 0.48, P < 0.05). Intramuscular fat content did not correlate with ACC or [DELTA]6d protein expression (P = 0.23 and P = 0.80, respectively). We conclude that SCD might be an effective potential biomarker for intramuscular fat deposition. Key words: intramuscular fat, lipogenic enzyme expression, meat quality, pig, subcutaneous fat doi: 10.2527/jas.2009-2091

Deletion of the murein (Braun) lipoprotein gene, Ipp, attenuates the Yersinia pestis CO92 strain in mouse models of bubonic and pneumonic plague. In this report, we characterized the virulence of strains from which the plasminogen activating protease (pla)-encoding pPCP1 plasmid was cured from either the wild-type (WT) or the [DELTA]/pp mutant strain of Y. pestis CO92 in the mouse model of pneumonic infection. We noted a significantly increased survival rate in mice infected with the Y. pestis pPCP-/[DELTA]/pp mutant strain up to a dose of 5000 [LD.sub.50]. Additionally, mice challenged with the [pPCP.sup.-]/[DELTA]/pp strain had substantially less tissue injury and a strong decrease in the levels of most cytokines and chemokines in tissue homogenates and sera when compared with the WT-infected group. Importantly, the Y. pestis [pPCP.sup.-]/[DELTA]/pp mutant strain was detectable in high numbers in the livers and spleens of some of the infected mice. In the lungs of [pPCP.sup.-]/[DELTA]/pp mutant-challenged animals, however, bacterial numbers dropped at 48 h after infection when compared with tissue homogenates from 1 h post-infection. Similarly, we noted that this mutant was unable to survive within murine macrophages in an in vitro assay, whereas survivability of the [pPCP.sup.-] mutant within the macrophage environment was similar to that of the WT. Taken together, our data indicated that a significant and possibly synergistic attenuation in bacterial virulence occurred in a mouse model of pneumonic plague when both the Ipp gene and the virulence plasmid pPCP1 encoding the pla gene were deleted from Y. pestis. DOI 10.1099/mic.0.029124-0

Although Streptococcus agalactiae, the group B Streptococcus, is a leading cause of invasive neonatal disease worldwide the molecular basis of its virulence is still poorly understood. To investigate the role of lipoproteins in the physiology and interaction of this pathogen with host cells, we generated a mutant S. agalactiae strain (A909[DELTA]Lgt) deficient in the Lgt enzyme and thus unable to lipidate lipoprotein precursors (pro-lipoproteins). The loss of pro-lipoprotein lipidation did not affect the viability of S. agalactiae or its growth in several different media, including cation-depleted media. The processing of two well-characterized lipoproteins, but not a non-lipoprotein, was clearly shown to be aberrant in A909[DELTA]Lgt. The mutant strain was shown to be more sensitive to oxidative stress in vitro although the molecular basis of this increased sensitivity was not apparent. The inactivation of Lgt also resulted in changes to the bacterial cell envelope, as demonstrated by reduced retention of both the group B carbohydrate and the polysaccharide capsule and a statistically significant reduction (P=0.0079) in A909[DELTA]Lgt adherence to human endothelial cells of fetal origin. These data confirm that failure to process lipoproteins correctly has pleiotropic effects that may be of significance to S. agalactiae colonization and pathogenesis.

Atherosclerosis is a chronic inflammatory disease characterized by the accumulation of oxidized lipoproteins and apoptotic cells. Adaptive immune responses to various oxidation-specific epitopes play an important role in atherogenesis. However, accumulating evidence suggests that these epitopes are also recognized by innate receptors, such as scavenger receptors on macrophages, and plasma proteins, such as C-reactive protein (CRP). Here, we provide multiple lines of evidence that oxidation-specific epitopes constitute a dominant, previously unrecognized target of natural Abs (NAbs) in both mice and humans. Using reconstituted mice expressing solely IgM NAbs, we have shown that approximately 30% of all NAbs bound to model oxidation-specific epitopes, as well as to atherosclerotic lesions and apoptotic cells. Because oxidative processes are ubiquitous, we hypothesized that these epitopes exert selective pressure to expand NAbs, which in turn play an important role in mediating homeostatic functions consequent to inflammation and cell death, as demonstrated by their ability to facilitate apoptotic cell clearance. These findings provide novel insights into the functions of NAbs in mediating host homeostasis and into their roles in health and diseases, such as chronic inflammatory diseases and atherosclerosis., Introduction Although hypercholesterolemia is necessary for the initiation and progression of atherosclerosis, there is now abundant evidence that immune mechanisms are also central to all phases of lesion development (1), [...]

The uptake of lipoproteins by macrophages is a critical step in the development of atherosclerotic lesions. Cultured monocyte-derived macrophages take up large amounts of native LDL by receptor-independent fluid-phase pinocytosis, either constitutively or in response to specific activating stimuli, depending on the macrophage phenotype. We therefore sought to determine whether fluid-phase pinocytosis occurs in vivo in macrophages in atherosclerotic lesions. We demonstrated that fluorescent pegylated nanoparticles similar in size to LDL (specifically nontargeted Qtracker quantum dot and AngioSPARK nanoparticles) can serve as models of LDL uptake by fluid-phase pinocytosis in cultured human monocyte--derived macrophages and mouse bone marrow--derived macrophages. Using fluorescence microscopy, we showed that atherosclerosis-prone Apoe-knockout mice injected with these nanoparticles displayed massive accumulation of the nanoparticles within [CD68.sup.+] macrophages, including lipid-containing foam cells, in atherosclerotic lesions in the aortic arch. Similar results were obtained when atherosclerotic mouse aortas were cultured with nanoparticles in vitro. These results show that macrophages within atherosclerotic lesions can take up LDL-sized nanoparticles by fluid-phase pinocytosis and indicate that fluid-phase pinocytosis of LDL is a mechanism for macrophage foam cell formation in vivo., Introduction Macrophage uptake of lipoproteins, especially LDL, is considered a critical process in the development of atherosclerosis, causing transformation of the macrophages into foam cells, thus promoting cholesterol accumulation and [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.cell.2009.02.041 Byline: C. Mark Fletcher (1), Michael J. Coyne (1), Otto F. Villa (2), Maria Chatzidaki-Livanis (1), Laurie E. Comstock (1) Keywords: MICROBIO Abstract: The Bacteroides are a numerically dominant genus of the human intestinal microbiota. These organisms harbor a rare bacterial pathway for incorporation of exogenous fucose into capsular polysaccharides and glycoproteins. The infrequency of glycoprotein synthesis by bacteria prompted a more detailed analysis of this process. Here, we demonstrate that Bacteroides fragilis has a general O-glycosylation system. The proteins targeted for glycosylation include those predicted to be involved in protein folding, protein-protein interactions, peptide degradation as well as surface lipoproteins. Protein glycosylation is central to the physiology of B. fragilis and is necessary for the organism to competitively colonize the mammalian intestine. We provide evidence that general O-glycosylation systems are conserved among intestinal Bacteroides species and likely contribute to the predominance of Bacteroides in the human intestine. Author Affiliation: (1) Channing Laboratory, Brigham & Women's Hospital, Harvard Medical School, 181 Longwood Avenue, Boston, MA 02115, USA (2) Pulmonary Critical Care and Sleep Division, Department of Medicine, Mount Sinai School of Medicine, 1468 Madison Avenue, New York, NY 10029, USA Article History: Received 8 October 2008; Revised 31 December 2008; Accepted 19 February 2009 Article Note: (miscellaneous) Published: April 16, 2009

Mycoplasma penetrans has the ability to change its surface lipoprotein profiles frequently. The P35 family lipoproteins encoded by the mpl genes are key players in this profile variation. The M. penetrans HF-2 genome has 38 mpl genes that form three gene clusters. Most of these mpl genes have an invertible promoter sequence that is responsible for the ON/OFF switching of individual mpl gene expression. Here, we identified the recombinase that catalyses inversions of the mpl gene promoters. We focused on two open reading frames of the M. penetrans HF-2 genome, namely MYPE2900 and MYPE8180, which show significant homology to the tyrosine site-specific recombinase (Tsr) family proteins. Since genetic tools for M. penetrans are still not developed, we cloned the MYPE2900 and MYPE8180 genes and expressed them in Mycoplasma pneumoniae and Escherichia coll. The promoter regions of the mpl genes [p35 (MYPE6810) or p42 (MYPE6630) genes] were also introduced into M. pneumoniae and E. coil cells expressing MYPE2900 or MYPE8180. Inversion of these promoters occurred in the presence of the MYPE2900 gene but not in the presence of the MYPE8180 gene, indicating that the MYPE2900 gene product is the recombinase that catalyses mpl gene promoter inversions. We used a PCR-based method to detect mpl promoter inversion. This method also enabled us to detect inversions of 10 mpl gene promoters in M. penetrans HF-2 cells. All these promoter inversions occurred at the 12 bp inverted repeat (IR) sequences flanking the promoter sequence. The consensus sequence of these IRs was proposed as TAAYNNNDATTA (Y=C or T; D=A, G or T).

The role of lipoprotein diacylglyceryl transferase (Lgt) and lipoprotein signal peptidase (Lsp) responsible for processing lipoproteins was investigated in Streptococcus uberis, a common cause of bovine mastitis. In the absence of Lgt, three lipoproteins [MtuA (SUB0473), Hap (SUB1625) and an extracellular solute-binding protein (SUB0365)] were detected in extracellular locations. All were shown by Edman degradation analysis to be cleaved on the carboxy side of the LXXC lipobox. Detection of MtuA, a lipoprotein shown previously to be essential for infectivity and virulence, was used as a surrogate lipoprotein marker to locate and assess processing of lipoproteins. The absence of Lgt did not prevent location of MtuA to the cell membrane, its location in the wild-type strain but, in contrast to the situation with wild-type, did result in a widespread location of this protein. In the absence of both Lgt and Lsp, MtuA was similarly released from the bacterial cell. In such strains, however, the cell-associated MtuA represented the full-length gene product, indicating that Lsp was able to cleave non-lipidated (lipo)proteins but was not responsible for their release from this bacterium.

Enteroaggregative Escherichia coli (EAEC) is a pathogen implicated in several infant diarrhea or diarrheal outbreaks in areas of endemicity. Although multiple genes involved in EAEC pathogenesis have been identified, the overall mechanism of virulence is not well understood. Recently, a novel secretion system, called type VI secretion (T6S) system (T6SS), has been identified in EAEC and most animal or plant gram-negative pathogens. T6SSs are multicomponent cell envelope machines responsible for the secretion of at least two putative substrates, Hcp and VgrG. In EAEC, two copies of T6S gene clusters, called sci-1 and sci-2, are present on the pheU pathogenicity island. In this study, we focused our work on the sci-1 gene cluster. The Sci-I apparatus is probably composed of all, or a subset of, the 21 gene products encoded on the cluster. Among these subunits, some are shared by all T6SSs identified to date, including a ClpV-type AAA+ ATPase (SciG) and an IcmF (SciS) and an IcmH (SciP) homologue, as well as a putative lipoprotein (SciN). In this study, we demonstrate that sciN is a critical gene necessary for T6S-dependent secretion of the Hcp-like SciD protein and for biofilm formation. We further show that SciN is a lipoprotein, as shown by the inhibition of its processing by globomycin and in vivo labeling with [[sup.3]H]palmitic acid. SciN is tethered to the outer membrane and exposed in the periplasm. Sequestration of SciN at the inner membrane by targeting the +2 residue responsible for lipoprotein localization (Gly2Asp) fails to complement an sciN mutant for SciD secretion and biofilm formation. Together, these results support a model in which SciN is an outer membrane lipoprotein exposed in the periplasm and essential for the Sci-1 apparatus function.

The ultimate membrane localization and function of most of the 185 predicted Pseudomonas aeruginosa PAO1 lipoproteins remain unknown. We constructed a fluorescent lipoprotein, [CSFp.sup.OmlA]-ChFP, by fusing the signal peptide and the first four amino acids of the P. aeruginosa outer membrane lipoprotein OmlA to the monomeric red fluorescent protein mCherry (ChFP). When cells were plasmolyzed with 0.5 M NaCl, the inner membrane separated from the outer membrane and formed plasmolysis bays. This permits the direct observation of fluorescence in either the outer or inner membrane. [CSFP.sup.OmlA]-ChFP was shown to localize in the outer membrane by fluorescence microscopy and immunoblotting analysis of inner and outer membrane fractions. The site-directed substitution of the amino acids at positions +2, +3, and +4 in [CSFP.sup.OmlA]-ChFP was performed to test the effects on lipoprotein localization of a series of amino acid sequences selected from a panel of predicted lipoproteins. We confirmed [Asp.sup.+2] and [Lys.sup.+3] [Ser.sup.+4] function as inner membrane retention signals and identified four novel inner membrane retention signals: [CK.sup.+2] [V.sup.+3] [E.sup.+4], [CG.sup.+2] [G.sup.+3] [G.sup.+4], [CG.sup.+2] [D.sup.+3] [D.sup.+4], and [CQ.sup.+2] [G.sup.+3] [S.sup.+4]. These inner membrane retention signals are found in 5% of the 185 predicted P. aeruginosa lipoproteins. Full-length chimeras of predicted lipoproteins PA4370 and PA3262 fused to mCherry were shown to reside in the inner membrane and showed a nonuniform or patchy distribution in the membrane. The optical sectioning of cells producing [PA4370.sup.CGDD-ChFP] and [PA3262.sup.CDSQ]-ChFP by confocal microscopy improved the resolution and indicated a helix-like localization pattern in the inner membrane. The method described here permits the in situ visualization of lipoprotein localization and should work equally well for other membrane-associated proteins.

Small LDL and HDL particle size are characteristic of a proatherogenic lipoprotein profile. Aerobic exercise increases these particle sizes. Although visceral adipose tissue (VAT) has been strongly linked with dyslipidemia, the importance of intermuscular adipose tissue (IMAT) to dyslipidemia and exercise responses is less well understood. We measured exercise-associated changes in thigh IMAT and VAT and examined their relationships with changes in LDL and HDL particle size. Sedentary, dyslipidemic, overweight subjects (n = 73) completed 8-9 mo of aerobic training. Linear regression models were used to compare the power of IMAT change and VAT change to predict lipoprotein size changes. In men alone (n = 40), IMAT change correlated inversely with both HDL size change (r = -0.42, P = 0.007) and LDL size change (r = -0.52, P < 0.001). That is, reduction of IMAT was associated with a shift toward larger, less atherogenic lipoprotein particles. No significant correlations were observed in women. After adding VAT change to the model, IMAT change was the only significant predictor of either HDL size change (P = 0.034 for IMAT vs. 0.162 for VAT) or LDL size change (P = 0.004 for IMAT vs. 0.189 for VAT) in men. In conclusion, in overweight dyslipidemic men, exercise-associated change in thigh IMAT was inversely correlated with both HDL and LDL size change and was more predictive of these lipoprotein changes than was change in VAT. Reducing IMAT through aerobic exercise may be functionally related to some improvements in atherogenic dyslipidemia in men. aerobic training; visceral fat; adipose tissue; high-density lipoprotein size; low-density lipoprotein size

Fat-specific protein of 27 kDa (FSP27) is a highly expressed adipocyte protein that promotes triglyceride accumulation within lipid droplets. In this issue of the JCI, Nishino et al. show that FSP27 also helps to maintain the characteristically large unilocular lipid droplet structure within each white adipocyte (see the related article beginning on page 2808). Fragmentation of lipid droplets in white adipocytes from FSP27-KO mice caused both increased lipolysis and upregulation of genes enhancing mitochondrial oxidative metabolism. This increased energy expenditure in turn protected the mice from diet-induced obesity and insulin resistance. These new results highlight powerful mechanisms that tightly coordinate rates of triglyceride storage in lipid droplets with mitochondrial fatty acid oxidation in white adipocytes., The handling and disposal of large volumes of greasy cooking ingredients like lard and vegetable oils is a messy business as any restaurant manager will lament. Human physiology faces the [...]

Fish may use lipoproteins instead of albumin-bound fatty acids to fuel endurance exercise, but lipoprotein kinetics have never been measured in ectotherms. In vivo bolus injections of labeled very-low-density lipoproteins ([sup.3]H-VLDL labeled in vivo from donor fish) and continuous infusions of Intralipid ([sup.3]H-labeled artificial emulsion) were used to investigate the effects of prolonged exercise (6 h at 1.5 body length/s) and heparin (600 U/kg) on the turnover rate of circulating triacylglycerol (TAG) in rainbow trout. We hypothesized that swimming would stimulate TAG turnover rate to fuel working muscles and that heparin would reduce flux by releasing lipoprotein lipase (LPL) from endothelial cells. Results from both tracer methods show that the baseline TAG tumover rate of trout ranges from 24 to 49 [micro]mol TAG * [kg.sup.-1] * [min.sup.-1] and exceeds all values measured to date in endotherms. More important, this high resting turnover rate is not stimulated during swimming, because it can already cover several times the energy requirements of locomotion. The fact that heparin causes a 50% decrease in baseline TAG turnover rate suggests that fish LPL must be bound to the endothelium for normal tissue uptake of fatty acids supplied by lipoproteins, as in mammals. We propose that the high resting TAG turnover rate of rainbow trout could be needed by ectotherms for rapid restructuring of membrane phospholipids. The continuous tracer infusion method implemented here could be a versatile tool to investigate the potential role of lipoproteins in providing fatty acids for rapid homeoviscous adaptation. lipoproteins; lipoprotein lipase; prolonged exercise; oxidative fuel; fish metabolism; lipid kinetics; heparin; homeoviscous adaptation; tracer methodology; Oncorhynchus mykiss

Lipoprotein signal peptidase (lsp) is responsible for cleaving the signal peptide sequence of lipoproteins in gram-positive bacteria. Investigation of the role of Lsp in Streptococcus uberis, a common cause of bovine mastitis, was undertaken using the lipoprotein MtuA (a protein essential for virulence) as a marker. The S. uberis lsp mutant phenotype displayed novel lipoprotein processing. Not only was full-length (uncleaved) MtuA detected by Western blotting, but during late log phase, a lower-molecular-weight derivative of MtuA was evident. Similar analysis of an S. uberis double mutant containing insertions disrupting both lsp and eep (a homologne of the Enterococcus faecalis 'enhanced expression of pheromone' gene) indicated a role for eep in cleavage of lipoproteins in the absence of Lsp. Such a function may indicate a role for eep in maintenance of secretion pathways during disruption of normal lipoprotein processing.

OxyR controls [H.sub.2][O.sub.2]-dependent gene expression in Pseudomonas aeruginosa. Without OxyR, diluted (< [10.sup.7]/ml) organisms are easily killed by micromolar [H.sub.2][0.sub.2]. The goal of this study was to define proteins that contribute to oxyR mutant survival in the presence of [H.sub.2][O.sub.2]. We identified proteins in an oxyR mutant that were oxidized by using 2,4-dinitrophenylhydrazine for protein carbonyl detection, followed by identification using a two-dimensional gel/matrix-assisted laser desorption ionization--time of flight approach. Among these was the peptidoglycan-associated lipoprotein, OprL. A double oxyR oprL mutant was constructed and was found to be more sensitive to [H.sub.2][0.sub.2] than the oxyR mutant. Provision of the OxyR-regulated alkyl hydroperoxide reductase, AhpCF, but not AhpB or the catalase, KatB, helped protect this strain against [H.sub.2] [0.sub.2.] Given the sensitivity of oxyR oprL bacteria to planktonic [H.sub.2][0.sub.2], we next tested the hypothesis that the biofilm mode of growth might protect such organisms from [H.sub.2][0.sub.2] -mediated killing. Surprisingly, biofilm-grown oxyR oprL mutants, which (in contrast to planktonic cells) possessed no differences in catalase activity compared to the oxyR mutant, were sensitive to killing by as little as 0.5 mM [H.sub.2][0.sub.2]. Transmission electron microscopy studies revealed that the integrity of both cytoplasmic and outer membranes of oxyR and oxyR oprL mutants were compromised. These studies suggest that sensitivity to the important physiological oxidant [H.sub.2][0.sub.2] in the exquisitely sensitive oxyR mutant bacteria is based not only upon the presence and location of OxyR-controlled antioxidant enzymes such as AhpCF but also on structural reinforcement by the peptidoglycan-associated lipoprotein OprL, especially during growth in biofilms.

Increased baseline values of the acute-phase reactant C-reactive protein (CRP) are significantly associated with future cardiovascular disease, and some in vitro studies have claimed that human CRP (hCRP) has proatherogenic effects. In vivo studies in apolipoprotein E-deficient mouse models, however, have given conflicting results. We bred atherosclerosis-prone mice ([Apob.sup.100/100][Ldlr.sup.-/-]), which have human-like hypercholesterolemia, with hCRP transgenic mice ([hCRP.sup.+l0]) and studied lesion development at 15, 30, 40, and 50 weeks of age. Atherosclerotic lesions were smaller in [hCRP.sup.+/0] [Apob.sup.100/100][Ldlr.sup.-I-] mice than in [hCRP.sup.0/0][Apob.sup.100/100][Ldlr.sup.-/-] controls, as judged from the lesion surface areas of pinned-out aortas from mice at 40 and 50 weeks of age. In lesions from 40-week-old mice, mRNA expression levels of several genes in the proteasome degradation pathway were higher in [hCRP.sup.+/0][Apob.sup.100/100][Ldlr.sup.-l-] mice than in littermate controls, as shown by global gene expression profiles. These results were confirmed by real-time PCR, which also indicated that the activities of those genes were the same at 30 and 40 weeks in [hCRP.sup.+/0][Apob.sup.100/100][Ldlr.sup.-/-] mice but were significantly lower at 40 weeks than at 30 weeks in controls. Our results show that hCRP is not proatherogenic but instead slows atherogenesis, possibly through proteasome-mediated protein degradation. acute-phase protein | apolipoprotein B100 | coronary artery disease | low-density lipoprotein | plaques

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.tins.2006.09.002 Byline: Olav M. Andersen, Thomas E. Willnow Abstract: Lipoprotein receptors have important roles in pathological processes that lead to Alzheimer's disease (AD). Previously, they were believed to act mainly by modulating the neuronal metabolism of cholesterol and apolipoprotein E, major risk factors for spontaneous AD. However, recent findings point towards an unexpected new function for lipoprotein receptors in regulation of intracellular transport and processing of the amyloid precursor protein (APP) to give amyloid-[beta] peptide, the principal component of senile plaques. Here, we will discuss how lipoprotein receptors might modulate distinct steps in neuronal trafficking of APP, and how an intricate balance between opposing receptor activities might be a crucial determinant of APP processing, and of onset and progression of neurodegeneration. Author Affiliation: Max-Delbrueck-Center for Molecular Medicine, D-13125 Berlin, Germany

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.tibs.2006.08.002 Byline: Florence Y. Lee (1), Hans Lee (1), Melissa L. Hubbert (1), Peter A. Edwards (1)(2)(3), Yanqiao Zhang (1)(2) Abstract: The farnesoid X receptor (FXR) is a ligand-activated transcription factor and a member of the nuclear receptor superfamily. In the past six years, remarkable inroads have been made into determining the functional importance of FXR. This receptor has been shown to have crucial roles in controlling bile acid homeostasis, lipoprotein and glucose metabolism, hepatic regeneration, intestinal bacterial growth and the response to hepatotoxins. Thus, the development of FXR agonists might prove useful for the treatment of diabetes, cholesterol gallstones, and hepatic and intestinal toxicity. Author Affiliation: (1) Department of Biological Chemistry, University of California at Los Angeles, CA 90095, USA (2) Department of Medicine, David Geffen School of Medicine, University of California at Los Angeles, CA 90095, USA (3) The Molecular Biology Institute, University of California at Los Angeles, CA 90095, USA

The outer membrane of most Gram-negative bacteria is made up of LPS, and in nearly all bacteria that contain LPS it is essential for the life of the organism. The lipid portion of this molecule, lipid A, also known as endotoxin, is a potent activator of the innate immune response. More than 50 genes are required to synthesize LPS and assemble it at the cell surface. Enormous progress has been made in elucidating the structure and biosynthesis of LPS, but until recently the cellular components required for its transport from its site of synthesis in the inner membrane to its final cellular location at the cell surface remained elusive. Here we describe the identification of a protein complex that functions to assemble LPS at the surface of the cell. This complex contains two proteins: Imp, already identified as an essential outer-membrane protein implicated in LPS assembly; and another protein, RIpB, heretofore identified only as a rare lipoprotein. We show that RIpB is also essential for cell viability and that the Imp/RIpB complex is responsible for LPS reaching the outer surface of the outer membrane. essential lipoprotein | Gram-negative bacteria | outer-membrane biogenesis

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2004.05.018 Byline: Kevin J. McGraw, Geoffrey E. Hill, Robert S. Parker Abstract: Many sexually selected traits are thought to be costly to produce, which ensures that they communicate information honestly to conspecifics. Carotenoid pigmentation is classically considered as a costly sexual signal in many fish and birds. It is often argued that carotenoid colours are 'condition dependent', with an individual's nutritional or health state directly determining trait expression. However, few studies have investigated precisely how a compromised nutritional state affects an animal's capacity to develop these sexually attractive colours. Here, we studied the effect of food restriction on the ability of male American goldfinches to physiologically process carotenoids during the period of feather growth. We used high-performance liquid-chromatography to determine the types and amounts of carotenoids circulating in blood during moult as well as in newly grown colourful feathers. We show that nutritional deprivation affects the degree to which male goldfinches transport carotenoids through the bloodstream. Food-restricted males circulated significantly less blood carotenoids than controls. They also incorporated less carotenoids into feathers and grew less colourful plumage, but the decrease in plumage carotenoids did not significantly exceed the depressed amounts already present in blood. These results suggest that the means by which these yellow-coloured passerines either extract carotenoids from food (e.g. via lipoidal micelles) or transport them through blood (e.g. via lipoproteins) are more sensitive to changes in nutritional/energy state than are the mechanisms for metabolizing dietary pigments or depositing metabolites into feathers. Author Affiliation: (*) Department of Neurobiology and Behavior, Cornell University, U.S.A. (a ) Department of Biological Sciences, Auburn University,U.S.A. (a ) Division of Nutritional Sciences, Cornell University, U.S.A. Article History: Received 26 January 2004; Revised 7 April 2004; Accepted 13 May 2004 Article Note: (miscellaneous) MS. number: A9803R

Lipoprotein(a) [Lp(a)] is considered a risk factor for coronary heart disease, Our aim was to investigate the effect of individual fatty acids on postprandial plasma Lp(a) and its association with lipemia and tissue plasminogen activator (t-PA). Five test fats dominated by (approximately 43% g/kg) stearic (S), palmitic (P), oleic, C18:1 trans (T), or linoleic acid were produced by interesterification. Sixteen young healthy men were served the individual test fats incorporated into meals (1g fat/kg body wt) after a 12-h fast in random order on different days, separated by 3-wk washout periods. Blood samples were drawn before and 2, 4, 6, and 8 h after eating. There was a pronounced increase in Lp(a) concentrations after intake of the test meals, and the test fats resulted in a difference in Lp(a) response (P < 0.001 ; diet x time interaction). However, T fat did not change Lp(a) during the time course studied. T fat resulted in less area under the plasma Lp(a) concentration curve compared to S and P fat (P [less than or equal to] 0.003). Test fat with saturated fatty acids resulted in the highest Lp(a) and lowest plasma triacylglycerol (TAG) response, with the reversed situation for T fat. There was no association between Lp(a) and t-PA. In conclusion, intake of meals high in individual dietary fatty acids increased postprandial plasma Lp(a) differently. There seems to be a complex regulatory role of plasma TAG on nonfasting plasma Lp(a) concentrations. KEY WORDS: * lipoprotein(a) * postprandial lipemia * stearic acid * trans fatty acid * oleic acid

Although oxidatively damaged lipoproteins are implicated in vascular injury, there is little information regarding the role of high-density lipoprotein (HDL) oxidation in atherogenesis. One potential pathway involves hypochlorous acid (HOCl) produced by myeloperoxidase (MPO), a heme protein secreted by phagocytes. We previously showed that 3-chlorotyrosine is a specific product of HOCl. Therefore, to explore the role of oxidized HDL in the pathogenesis of vascular disease, we used MS to quantify 3-chlorotyrosine in HDL isolated from plasma and atherosclerotic tissue. HDL from human aortic atherosclerotic intima had an 8-fold higher level of 3-chlorotyrosine than plasma HDL Tandem MS analysis identified MPO as a component of lesion HDL, suggesting that the two interact in the artery wall. Moreover, immunohistochemical studies found that specific epitopes derived from HOCI colocalized with apolipoprotein A-I, the major protein of HDL. These observations strongly support the hypothesis that MPO promotes HDL oxidation in the human artery wall. Levels of 3-chlorotyrosine were elevated in HDL isolated from the blood of humans with established coronary artery disease, suggesting that circulating levels of oxidized HDL represent a unique marker for clinically significant atherosclerosis. HDL or lipid-free apolipoprotein A-I exposed to HOCl was less able to remove cholesterol from cultured cells by a pathway requiring the cell membrane transporter ATP-binding cassette transporter A1. The detection of 3-chlorotyrosine in HDL isolated from vascular lesions raises the possibility that MPO, by virtue of its ability to form HOCl, may promote atherogenesis by counteracting the established antiatherogenic effects of HDL and the ATP-binding cassette transporter A1 pathway.

Cells of Flavobacterium johnsoniae move rapidly over surfaces by gliding motility. The mechanism of this form of motility is not known. Six genes (gldA, gldB, gldD, gldF, gldG, and ftsX) that are required for gliding have been described. Tn4351 mutagenesis was used to identify another gene, gldH, which is required for cell movement. GldH mutants formed nonspreading colonies, and individual cells lacked the cell movements and ability to propel latex spheres along their surfaces that are characteristic of wild-type cells, gldH mutants also failed to digest chitin and were resistant to bacteriophages that infect wild-type cells. Introduction of pMM293, which carries wild-type gldH, restored to the gldH mutants colony spreading, cell motility, the ability to move latex spheres, phage sensitivity, and the ability to digest chitin, gldH encodes a predicted 141-amino-acid protein that localized to the membrane fraction. Labeling studies with [sup.3.H]palmitate demonstrated that GldH is a lipoprotein. GldB and GldD, which were previously described, also appear to be lipoproteins. GldH does not exhibit significant amino acid similarity to proteins of known function in the databases. Putative homologs of gldH of unknown function are found in motile (Cytophaga hutchinsonii) and apparently nonmotile (Bacteroides thetaiotaomicron, Bacteroides fragilis, Tannerella forsythensis, Porphyromonas gingivalis, and Prevotella intermedia) members of the Cytophaga-Flavobacterium-Bacteroides group.