The evaluation of curcumin effects on some acute phase proteins in aflatoxin B1 applied rats

This study was designed to determine the effects of curcumin on some acute phase proteins in rats treated with aflatoxin B1. In this study, healthy 38 male Wistar Albino rats were used. The animals in control group were given food and distilled water. The animals in DMSO group were orally given 1 ml 10% DMSO daily for 60 days, animals in Cur group was orally given 300mg/kg curcumin dissolved in 10% DMSO daily for 60 days. Animals in AFB1 group were orally given 250µg/kg aflatoxin B1 dissolved in 10% DMSO daily for 60 days. Animals in AFB1+Cur group was orally given 250µg/kg aflatoxin B1 dissolved in 10% DMSO and 300mg/kg curcumin dissolved in 10% DMSO daily for 60 days. In blood samples taken from all animals, fibrinogen, prothrombin, albumin and CRP levels were determined. In this study, fibrinogen, prothrombin and CRP levels with AFB1 group were found to be significantly higher than the control group (p<0.05). In the AFB1+Cur group, fibrinogen and CRP levels were lower than in the aflatoxin group (p<0.05). In the study, it was observed that albumin level in rats in AFB1 group significantly decreased compared to the control group (p<0.05) and this difference was found to be eliminated depend on the application of curcumin together with aflatoxin B1 (p<0.05). In conclusion, our findings regarding the ameliorating effects of curcumin on acute phase protein abnormalities caused by aflatoxicosis will contribute to future research.

Lipopolysaccharide-binding protein (LBP) can reverse the amyloid state of fibrin seen or induced in Parkinson's disease

The thrombin-induced polymerisation of fibrinogen to form fibrin is well established as a late stage of blood clotting. It is known that Parkinson's Disease (PD) is accompanied by dysregulation in blood clotting, but it is less widely known as a coagulopathy. In recent work, we showed that the presence of tiny amounts of bacterial lipopolysaccharide (LPS) in healthy individuals could cause clots to adopt an amyloid form, and this could be observed via scanning electron microscopy (SEM) or via the fluorescence of thioflavin-T. This could be prevented by the prior addition of lipopolysaccharide-binding protein (LBP). We had also observed by SEM this unusual clotting in the blood of patients with Parkinson's Disease. We hypothesised, and here show, that this too can be prevented by LBP in the context of PD. This adds further evidence implicating inflammatory microbial cell wall products as an accompaniment to the disease, and may be part of its aetiology. This may lead to novel treatment strategies in PD designed to target microbes and their products.

[A experiment research of beryllium oxide induced oxidative lung injury and the protective effects of LBP in rats]

OBJECTIVE

To explore beryllium oxide induced oxidative lung injury and the protective effects of LBP.

METHODS

Intoxication of animals were induced by once intratracheal injection and LBP intervention by intragastric administration. The content of HIF-1, VEGF and HO-1 of lung tissues were measured by kits. The pathological changes of lung tissue were showed by pathological section. The changes of lung ultrastructure were observed by electron microscope.

RESULTS

Pathological changes of the lung tissue in beryllium oxide exposure group rats were in line with the characteristics of beryllium disease in human. Compared with the control group, HO-1 was increased in beryllium oxide exposure 40 d group and low doses of LBP group, compared with the control group, HO-1 was increased in beryllium oxide exposure 80d group and LBP treatment groups (P < 0.05 or P < 0.01). Compared with the control group, HIF-1 was increased in beryllium oxide exposure 40 d group, LBP treatment groups, beryllium oxide exposure 60 d and 80 d groups (P < 0.05 or P < 0.01). Compared with the control group, VEGF was increased of all phases, especially in beryllium oxide exposure 40d and 80 groups, LBP treatment groups and beryllium oxide exposure 60 d (P < 0.05 or P < 0.01). The content of HO-1 of beryllium oxide exposure group was higher than the LBP treatment for 40d group but below LBP treatment for 80 d group (P < 0.05). The content of HIF1 of beryllium oxide exposure group was higher than high dose of LBP treatment for 60d group and LBP treatment for 80 d group (P < 0.01). The content of VEGF of beryllium oxide exposure group was higher than LBP treatment for 40 d group and high dose of LBP treatment for 60 d (P < 0.05 or P < 0.01).

CONCLUSIONS

BeO can cause abnormal expression of related genes of lung tissue in rats, LBP has protective effects on BeO caused lung injury.

Recombinant human lipocalin 2 acts as an antibacterial agent to prevent platelet contamination

BACKGROUND

Bacterial contamination of platelet products is the major infectious risk in blood transfusion medicine, which can result in life-threatening sepsis in recipient. Lipocalin 2 (Lcn2) is an iron-sequestering protein in the antibacterial innate immune response, which inhibit bacterial growth. This study was aimed to evaluate the antibacterial property of Lcn2 in preventing bacterial contamination of platelets.

METHODS

Recombinant Lcn2 was expressed in a eukaryotic expression system and following purification and characterization of the recombinant Lcn2, its minimum inhibitory concentration was determined. Then, platelet concentrates were inoculated with various concentrations of Staphylococcus epidermidis, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, and Enterococcus faecalis, and the antibacterial effects of Lcn2 was evaluated at 20-24 °C.

RESULTS

Results revealed that Lcn2 effectively inhibited the growth of 1.5 × 10(4) CFU/ml S. epidermidis, P. aeruginosa, K. pneumoniae, E. coli, and E. faecalis at 40 ng/ml. At this concentration, Lcn2 also inhibited the growth of 1.5 × 10(3) CFU/ml Staphylococcus aureus and Proteus mirabilis.

CONCLUSION

Recombinant Lcn2 inhibited growth of a variety of platelet-contaminating bacteria. Therefore, supplementation of platelet concentrates with Lcn2 may reduce bacterial contamination.

Neutrophil gelatinase-associated lipocalin increases HLA-G(+)/FoxP3(+) T-regulatory cell population in an in vitro model of PBMC

Background

Neutrophil gelatinase-associated lipocalin (NGAL) is emerging as a mediator of various biological and pathological states. However, the specific biological role of this molecule remains unclear, as it serves as a biomarker for many conditions. The high sensitivity of NGAL as a biomarker coupled with relatively low specificity may hide important biological roles. Data point toward an acute compensatory, protective role for NGAL in response to adverse cellular stresses, including inflammatory and oxidative stress. The aim of this study was to understand whether NGAL modulates the T-cell response through regulation of the human leukocyte antigen G (HLA-G) complex, which is a mediator of tolerance.

Methodology/Principal Findings

Peripheral blood mononuclear cells (PBMCs) were obtained from eight healthy donors and isolated by centrifugation on a Ficoll gradient. All donors gave informed consent. PBMCs were treated with four different concentrations of NGAL (40–320 ng/ml) in an iron-loaded or iron-free form. Changes in cell phenotype were analyzed by flow cytometry. NGAL stimulated expression of HLA-G on CD4+ T cells in a dose- and iron-dependent manner. Iron deficiency prevented NGAL-mediated effects, such that HLA-G expression was unaltered. Furthermore, NGAL treatment affected stimulation of regulatory T cells and in vitro expansion of CD4⁺ CD25⁺ FoxP3⁺ cells. An NGAL neutralizing antibody limited HLA-G expression and significantly decreased the percentage of CD4⁺ CD25⁺ FoxP3⁺ cells.

Conclusions/Significance

We provide in vitro evidence that NGAL is involved in cellular immunity. The potential role of NGAL as an immunomodulatory molecule is based on its ability to induce immune tolerance by upregulating HLA-G expression and expansion of T-regulatory cells in healthy donors. Future studies should further evaluate the role of NGAL in immunology and immunomodulation and its possible relationship to immunosuppressive therapy efficacy, tolerance induction in transplant patients, and other immunological disorders.

Parental transfer of the antimicrobial protein LBP/BPI protects Biomphalaria glabrata eggs against oomycete infections

Vertebrate females transfer antibodies via the placenta, colostrum and milk or via the egg yolk to protect their immunologically immature offspring against pathogens. This evolutionarily important transfer of immunity is poorly documented in invertebrates and basic questions remain regarding the nature and extent of parental protection of offspring. In this study, we show that a lipopolysaccharide binding protein/bactericidal permeability increasing protein family member from the invertebrate Biomphalaria glabrata (BgLBP/BPI1) is massively loaded into the eggs of this freshwater snail. Native and recombinant proteins displayed conserved LPS-binding, antibacterial and membrane permeabilizing activities. A broad screening of various pathogens revealed a previously unknown biocidal activity of the protein against pathogenic water molds (oomycetes), which is conserved in human BPI. RNAi-dependent silencing of LBP/BPI in the parent snails resulted in a significant reduction of reproductive success and extensive death of eggs through oomycete infections. This work provides the first functional evidence that a LBP/BPI is involved in the parental immune protection of invertebrate offspring and reveals a novel and conserved biocidal activity for LBP/BPI family members.

Vertebrate immune systems not only protect adult organisms against infections but also increase survival of offspring through parental transfer of innate and adaptive immune factors via the placenta, colostrum and milk or via the egg yolk. This maternal transfer of immunity is critical for species survival as embryos and neonates are immunologically immature and unable to fight off infections at early life stages. Parental immune protection is poorly documented in invertebrates and how the estimated 1.3 million of invertebrate species protect their eggs against pathogens remains an intriguing question. Here, we show that a fresh-water snail, Biomphalaria glabrata massively loads its eggs with a lipopolysaccharide binding protein/bactericidal permeability increasing protein (LBP/BPI) displaying expected antibacterial activities. Remarkably, this snail LBP/BPI also displayed a strong biocidal activity against water molds (oomycetes). This yet unsuspected activity is conserved in human BPI. Gene expression knock-down resulted in the reduction of snail reproductive success and massive death of eggs after water mold infections. This work reveals a novel and conserved biocidal activity for LBP/BPI family members and demonstrates that the snail LBP/BPI represents a major fitness-related protein transferred from parents to their clutches and protecting them from widespread and lethal oomycete infections.

Lipocalin-2 increases fat oxidation in vitro and is correlated with energy expenditure in normal weight but not obese women

OBJECTIVE

The role of lipocalin-2 (Lcn2) was determined in regulating metabolism in cell, animal, and human models.

DESIGN AND METHODS

Adipocytes were treated with recombinant lipocalin-2 (rLcn2) to determine the effect on lipid metabolism. rLcn2 was injected into mice to determine the effect on metabolism in vivo. To assess the relationship between Lcn2 and fat oxidation (FatOx) in humans, normal weight (NW) and obese (OB) women were given three separate high fat (HF) meals followed by indirect calorimetry. The relationship between postprandial Lcn2 with macronutrient metabolism and total energy expenditure (TEE) using Pearson correlations was determined.

RESULTS

Lcn2 increased expression of genes involved in β-oxidation including peroxisome proliferator-activated receptor-δ in adipocytes, as well as (3) H labeled oleate β-oxidation. Lcn2 injected into chow-fed mice directly increased TEE by 18% after the first dark cycle (232 ± 1.4 cal vs. 341 ± 1.4 cal; PBS vs. Lcn2) and remained significantly elevated by 10% after the second dark cycle (296 ± 1.4 cal vs. 326 ± 1.4 cal; PBS vs. Lcn2). Lcn2 was correlated with TEE in all three HF meal challenges in NW but not OB females.

CONCLUSIONS

Lipocalin-2 is a novel adipokine that promotes FatOx and TEE and its function may be impaired in obesity.

Siderocalin/Lcn2/NGAL/24p3 does not drive apoptosis through gentisic acid mediated iron withdrawal in hematopoietic cell lines

Siderocalin (also lipocalin 2, NGAL or 24p3) binds iron as complexes with specific siderophores, which are low molecular weight, ferric ion-specific chelators. In innate immunity, siderocalin slows the growth of infecting bacteria by sequestering bacterial ferric siderophores. Siderocalin also binds simple catechols, which can serve as siderophores in the damaged urinary tract. Siderocalin has also been proposed to alter cellular iron trafficking, for instance, driving apoptosis through iron efflux via BOCT. An endogenous siderophore composed of gentisic acid (2,5-dihydroxybenzoic acid) substituents was proposed to mediate cellular efflux. However, binding studies reported herein contradict the proposal that gentisic acid forms high-affinity ternary complexes with siderocalin and iron, or that gentisic acid can serve as an endogenous siderophore at neutral pH. We also demonstrate that siderocalin does not induce cellular iron efflux or stimulate apoptosis, questioning the role siderocalin plays in modulating iron metabolism.

Isolation and characterization of pharmaceutical grade human pentraxins, serum amyloid P component and C-reactive protein, for clinical use

The human pentraxin proteins, serum amyloid P component (SAP) and C‐reactive protein (CRP) are important in routine clinical diagnosis, SAP for systemic amyloidosis and CRP for monitoring the non‐specific acute phase response. They are also targets for novel therapies currently in development but their roles in health and disease are controversial. Thus, both for clinical use and to rigorously elucidate their functions, structurally and functionally intact, pharmaceutical grade preparations of the natural, authentic proteins are required. We report here the production from normal human donor plasma and the characterization of the first such preparations. Importantly, we demonstrate that, contrary to reports using recombinant proteins and less well characterized preparations, neither CRP nor SAP stimulate the release by human peripheral blood mononuclear cells in vitro of any TNFα, IL‐6 or IL‐8, nor does SAP cause release of IL‐1β or IL‐10. Furthermore neither of our preparations was pro‐inflammatory in mice in vivo.

A family of helminth molecules that modulate innate cell responses via molecular mimicry of host antimicrobial peptides

Over the last decade a significant number of studies have highlighted the central role of host antimicrobial (or defence) peptides in modulating the response of innate immune cells to pathogen-associated ligands. In humans, the most widely studied antimicrobial peptide is LL-37, a 37-residue peptide containing an amphipathic helix that is released via proteolytic cleavage of the precursor protein CAP18. Owing to its ability to protect against lethal endotoxaemia and clinically-relevant bacterial infections, LL-37 and its derivatives are seen as attractive candidates for anti-sepsis therapies. We have identified a novel family of molecules secreted by parasitic helminths (helminth defence molecules; HDMs) that exhibit similar biochemical and functional characteristics to human defence peptides, particularly CAP18. The HDM secreted by Fasciola hepatica (FhHDM-1) adopts a predominantly α-helical structure in solution. Processing of FhHDM-1 by F. hepatica cathepsin L1 releases a 34-residue C-terminal fragment containing a conserved amphipathic helix. This is analogous to the proteolytic processing of CAP18 to release LL-37, which modulates innate cell activation by classical toll-like receptor (TLR) ligands such as lipopolysaccharide (LPS). We show that full-length recombinant FhHDM-1 and a peptide analogue of the amphipathic C-terminus bind directly to LPS in a concentration-dependent manner, reducing its interaction with both LPS-binding protein (LBP) and the surface of macrophages. Furthermore, FhHDM-1 and the amphipathic C-terminal peptide protect mice against LPS-induced inflammation by significantly reducing the release of inflammatory mediators from macrophages. We propose that HDMs, by mimicking the function of host defence peptides, represent a novel family of innate cell modulators with therapeutic potential in anti-sepsis treatments and prevention of inflammation.

Lipocalin-2-induced cytokine production enhances endometrial carcinoma cell survival and migration

Lipocalin-2 (Lcn-2) is an acute-phase protein that has been implicated in diverse physiological processes in mice, including: apoptosis, ion transport, inflammation, cell survival, and tumorigenesis. This study characterized the biological activity of Lcn-2 in human endometrial carcinoma cells (RL95-2). Exposure of RL95-2 cells to Lcn-2 for >24 h reduced Lcn-2-induced cell apoptosis, changed the cell proliferation and up-regulated cytokine secretions, including: interleukin-8 (IL-8), inteleukin-6 (IL-6), monocyte chemotatic protein-1 (MCP-1) and growth-related oncogene (GRO). However, IL-8 mRNA and protein levels were dramatically increased in Lcn-2-treated RL95-2 cells. To determine the IL-8 effect on Lcn-2-treated RL95-2 cells was our major focus. Adding recombinant IL-8 (rIL-8) resulted in decreased caspase-3 activity in Lcn-2-treated cells, whereas the addition of IL-8 antibodies resulted in significantly increased caspase-3 activity and decreased cell migration. Data indicate that IL-8 plays a crucial role in the induction of cell migration. Interestingly, Lcn-2-induced cytokines, secretion from RL95-2 cells, could not show the potent cell migration ability with the exception of IL-8. We conclude that Lcn-2 triggered cytokine secretions to prevent RL95-2 cells from undergoing apoptosis and subsequently increased cell migration. We hypothesize that Lcn-2 increased cytokine secretion by RL95-2 cells, which in turn activated a cellular defense system. This study suggests that Lcn-2 may play a role in the human female reproductive system or in endometrial cancer.

An ancient molecule with novel function: Alanine aminotransferase as a lipopolysaccharide binding protein with bacteriocidal activity

Alanine aminotransaminase (ALT) has been identified from bacteria to plants to animals including humans. The increase in serum ALT is regarded as an index for clinical diagnosis of liver function in humans. However, ALT elevation is also reported in non-liver injury conditions and in apparently healthy people, suggesting it may play a fundamental role physiologically. Herein we isolated an alt homolog, Amphialt, from Branchiostoma japonicus, an intermediatary species from invertebrates to vertebrates, which encoded a polypeptide of 500 amino acids with more than 62 and 52% sequence identity to vertebrate and invertebrate ALT isoenzymes, respectively. It was constitutively expressed in many tissues including the hepatic caecum, the precursor of liver, and its expression in the caecum was significantly up-regulated by challenge with lipopolysaccharides (LPS). Strikingly, recombinant AmphiALT, with a specific activity of 0.114±0.02U/mg, was capable of specifically binding to the Gram-negative bacteria Escherichia coli and Aeromonas hydrophila and to their conserved molecule LPS, as well as inhibiting the growth of E. coli and causing its lysis. In contrast, AmphiALT did not bind to the Gram-positive bacteria Staphyloccocus aureus and Bacillus subtilis as well as their conserved molecule LTA. In addition, a high homology noted between amphioxus and mammalian ALT sequences suggested a functional conservation of ALT evolutionarily, hinting at the clue that mammalian ALT may also play an antibacterial role similar to that of AmphiALT. Taken together, it is proposed that AmphiALT is an immune-relevant molecule capable of identifying LPS and causing damage to Gram-negative bacteria like E. coli and A. hydrophila. It also bolsters the notion that the hepatic caecum of amphioxus is the precursor of vertebrate liver, acting as a major tissue in acute phase response.

Differential effects of alpha1-acid glycoprotein on bovine neutrophil respiratory burst activity and IL-8 production

During bacterial-mediated diseases, neutrophils (PMNs) play a critical role in defending the host against invading pathogens. PMN production of reactive oxygen species (ROS) contributes to the bactericidal capabilities of these cells. ROS are produced intracellularly and can be released extracellularly. The aberrant extracellular release of ROS, however, has been reported to induce injury to host tissues during mastitis and other inflammatory-mediated diseases of cattle. The acute phase response, which occurs shortly after infection or tissue injury, is characterized by the induction of a large number of plasma proteins referred to as acute phase proteins (APP). alpha1-Acid glycoprotein (AGP) is an APP that increases in response to infection or injury in cattle and humans. The precise function of AGP is unknown, but it has been reported to possess anti-inflammatory properties. The objective of this study was to evaluate the effects of bovine AGP on PMN pro-inflammatory responses, including respiratory burst activity and cytokine production. Bovine AGP dose-dependently inhibited zymosan-induced PMN extracellular release of superoxide anion and hydrogen peroxide without affecting the capacity of PMN to engulf and kill Staphylococcus aureus. Moreover, AGP exerted its effect on ROS production regardless of whether PMNs were exposed to AGP prior to or after activation. In contrast to respiratory burst activity, AGP enhanced PMN production of IL-8. The precise mechanism by which AGP regulates PMN functions remains unknown, but data presented in this study suggest that AGP may have a complex role by differentially regulating PMN pro-inflammatory activities.

Acute-phase protein alpha-1-acid glycoprotein mediates neutrophil migration failure in sepsis by a nitric oxide-dependent mechanism

The reduction of circulating neutrophil migration to infection sites is associated with a poor outcome of severe sepsis. alpha-1-Acid glycoprotein (AGP) was isolated from the sera of severely septic patients by HPLC and acrylamide gel electrophoresis and identified by mass spectrometry. Both the isolated protein and commercial AGP inhibited carrageenin-induced neutrophil migration into the rat peritoneal cavity when administered i.v. at a dose of 4.0 microg per rat (95 pmol per rat). Analysis by intravital microscopy demonstrated that both proteins inhibited the rolling and adhesion of leukocytes in the mesenteric microcirculation. The inhibitory activity was blocked by 50 mg/kg aminoguanidine, s.c., and was not demonstrable in inducible nitric oxide synthase (iNOS) knockout mice. Incubation of AGP with neutrophils from healthy subjects induced the production of NO and inhibited the neutrophil chemotaxis by an iNOS/NO/cyclic guanosine 3,5-monophosphate-dependent pathway. In addition, AGP induced the l-selectin shedding by neutrophils. The administration of AGP to rats with mild cecal ligation puncture sepsis inhibited neutrophil migration and reduced 7-day survival from approximately 80% to 20%. These data demonstrate that AGP, an acute-phase protein, inhibits neutrophil migration by an NO-dependent process and suggest that AGP also participates in human sepsis.

A dual role of lipocalin 2 in the apoptosis and deramification of activated microglia

Activated microglia are thought to undergo apoptosis as a self-regulatory mechanism. To better understand molecular mechanisms of the microglial apoptosis, apoptosis-resistant variants of microglial cells were selected and characterized. The expression of lipocalin 2 (lcn2) was significantly down-regulated in the microglial cells that were resistant to NO-induced apoptosis. lcn2 expression was increased by inflammatory stimuli in microglia. The stable expression of lcn2 as well as the addition of rLCN2 protein augmented the sensitivity of microglia to the NO-induced apoptosis, while knockdown of lcn2 expression using short hairpin RNA attenuated the cell death. Microglial cells with increased lcn2 expression were more sensitive to other cytotoxic agents as well. Thus, inflammatory activation of microglia may lead to up-regulation of lcn2 expression, which sensitizes microglia to the self-regulatory apoptosis. Additionally, the stable expression of lcn2 in BV-2 microglia cells induced a morphological change of the cells into the round shape with a loss of processes. Treatment of primary microglia cultures with the rLCN2 protein also induced the deramification of microglia. The deramification of microglia was closely related with the apoptosis-prone phenotype, because other deramification-inducing agents such as cAMP-elevating agent forskolin, ATP, and calcium ionophore also rendered microglia more sensitive to cell death. Taken together, our results suggest that activated microglia may secrete LCN2 protein, which act in an autocrine manner to sensitize microglia to the self-regulatory apoptosis and to endow microglia with an amoeboid form, a canonical morphology of activated microglia in vivo.

High-density lipoproteins (HDL) inhibit endotoxin-induced leukocyte adhesion on endothelial cells in rats: effect of the acute-phase HDL

High-density lipoprotein (HDL) plays an important role not only in protecting against atherosclerosis but also in innate immunity. Several lines of evidence showed that HDL could ameliorate the toxic effects of endotoxin or lipopolysaccharide (LPS). In this study, we examined whether HDL could inhibit LPS-induced leukocyte adhesion on endothelial cells in rats. Normal HDL and acute-phase HDL (AP-HDL) were purified from plasma of hamsters that received normal saline and LPS injection, respectively. Wistar rats were given LPS injection and the number of leukocytes adhering to endothelial cells of the mesenteric venules was determined using intravital fluorescence videomicroscopy. Intravenous injection of LPS enhanced leukocyte adhesion to the mesenteric venules. However, when LPS was preincubated with normal HDL, leukocyte adhesion on endothelial cells in response to LPS was significantly attenuated in a dose-dependent manner. AP-HDL was also able to significantly decrease LPS-induced leukocyte adhesion on endothelial cells. It appeared to be more effective than normal HDL since lower concentrations were required. This inhibitory effect of HDL was not due to HDL itself but it requires preincubation of HDL with LPS. When HDL was separated into protein and lipid fractions, it was found that lipid-free apoHDL was able to significantly inhibit LPS-induced leukocyte adhesion, whereas lipid component of HDL had no effect. In conclusion, HDL, both normal and acute-phase, could inhibit an inflammatory effect of LPS on endothelial cells in vivo. AP-HDL was more potent than normal HDL in inhibiting LPS-induced leukocyte adhesion, and this effect was attributed to the protein component of HDL.

A role for neutral sphingomyelinase activation in the inhibition of LPS action by phospholipid oxidation products

Previous studies from our laboratory and others presented evidence that oxidized 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphatidylcholine (OxPAPC) and oxidized 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphatidylethanolamine can inhibit lipopolysaccharide (LPS)-mediated induction of interleukin-8 (IL-8) in endothelial cells. Using synthetic derivatives of phosphatidylethanolamine, we now demonstrate that phospholipid oxidation products containing alpha,beta-unsaturated carboxylic acids are the most active inhibitors we examined. 5-Keto-6-octendioic acid ester of 2-phosphatidylcholine (KOdiA-PC) was 500-fold more inhibitory than OxPAPC, being active in the nanomolar range. Our studies in human aortic endothelial cells identify one important mechanism of the inhibitory response as involving the activation of neutral sphingomyelinase. There is evidence that Toll-like receptor-4 and other members of the LPS receptor complex must be colocalized to the caveolar/lipid raft region of the cell, where sphingomyelin is enriched, for effective LPS signaling. Previous work from our laboratory suggested that OxPAPC could disrupt this caveolar fraction. These studies present evidence that OxPAPC activates sphingomyelinase, increasing the levels of 16:0, 22:0, and 24:0 ceramide and that the neutral sphingomyelinase inhibitor GW4869 reduces the inhibitory effect of OxPAPC and KOdiA-PC. We also show that cell-permeant C6 ceramide, like OxPAPC, causes the inhibition of LPS-induced IL-8 synthesis and alters caveolin distribution similar to OxPAPC. Together, these data identify a new pathway by which oxidized phospholipids inhibit LPS action involving the activation of neutral sphingomyelinase, resulting in a change in caveolin distribution. Furthermore, we identify specific oxidized phospholipids responsible for this inhibition.

Effects of mouse and human lipocalin homologues 24p3/lcn2 and neutrophil gelatinase-associated lipocalin on gastrointestinal mucosal integrity and repair

BACKGROUND & AIMS

The lipocalin superfamily, including the mouse and human homologues 24p3/lcn2 and neutrophil gelatinase-associated lipocalin, show great functional diversity including roles in olfaction, transportation, and prostaglandin synthesis in mammals. Their potential role in maintaining gastrointestinal mucosal integrity and repair is, however, unclear.

METHODS

Changes in 24p3/lcn2 expression in the mouse gut in response to various noxious agents were examined using Northern blot, in situ hybridization, and immunohistochemistry. Effects of recombinant 24p3/lcn2 on proliferation ([3H]-thymidine uptake), and restitution (cell-wounding migration) were assessed using human colonic HT29 and HCT116 cells. In addition, the effects of recombinant 24p3/lcn2 on the amount of gastric damage were assessed in rats treated with indomethacin (20 mg/kg) and restraint.

RESULTS

Marked up-regulation of expression of 24p3/lcn2 was seen throughout the gut in response to indomethacin or dextran sodium sulfate treatment. Expression was increased particularly in the surface epithelial cells and infiltrating inflammatory cells. Proliferation and restitution assays in the presence of recombinant wild-type sequence neutrophil gelatinase-associated lipocalin, wild-type cys(98)-24p3/lcn2, and mutant ala98-24p3/lcn2 showed that all 3 peptides caused a 3- to 4-fold increase in promigratory activity (P < .01 vs control) but did not influence proliferation. The administration of wild-type cys98-, or mutant ala98-24p3/lcn2 (25 and 50 microg/kg/h, respectively), given via the subcutaneous route, both caused similar reductions in the rat gastric damage model (60% reduction at highest dose, P < .01 vs control), although oral administration was ineffective.

CONCLUSIONS

24p3/lcn2 facilitates mucosal regeneration by promoting cell migration.

LBP inhibitory peptide reduces endotoxin-induced macrophage activation and mortality

OBJECTIVE AND DESIGN

The aim of this study was to investigate whether P12, a lipopolysaccharide (LPS)-binding protein (LBP) inhibitory peptide could reduce LPS induced inflammation in vitro and in vivo.

MATERIAL AND METHODS

Human monocyte-like cell line (U937 cells) was grown in RPMI 1640 and stimulated with PMA in order to induce differentiation to the macrophage stage. A total of 70 Kunming mice (8-12 wk old) were used in our experiments. The effects of P12 on the binding of LPS to U937 cells and alveolar macrophages (AMs) were determined by flow cytometric analysis. Nuclear factor kappa B (NF-kappa B) translocation was evaluated with subunit P65 by Western blotting. The production of tumor necrosis factor-alpha (TNF-alpha), alanine transaminase (ALT), and nitric oxide (NO) as measured by ELISA, enzymatic activity assay, and enzymatic assay with nitrate reductase. Differences among groups were determined using one-way ANOVA test and Fisher exact test.

TREATMENT

U937 cells were treated with LPS, LBP, and indicated concentrations of P12. Mice were administered LPS intraperitoneally and P12 via the tail vein.

RESULTS

P12 inhibited the binding of FITC-conjugated LPS (FITC-LPS) to U937 cells and AMs. NF-kappa B translocation and the production of TNF-alpha, ALT, and NO induced by LPS was also significantly suppressed by P12. Furthermore P12 protected mice from LPS-induced death.

CONCLUSIONS

The results suggest that blockade of LBP at inflammation sites might attenuate LPS-induced circulatory shock. This results in a beneficial effect in a mouse model of endotoxemia.

On mouse and man: neutrophil gelatinase associated lipocalin is not involved in apoptosis or acute response

Neutrophil gelatinase-associated lipocalin (NGAL) is a siderphore binding molecule present in the specific granules of neutrophils and induced in a variety of epithelial cells during inflammation. Its mouse orthologue, 24p3, is also an acute phase protein synthesized in the liver and adipose tissue during inflammation. 24p3 has recently been implicated in apoptosis of myeloid cells. We investigated whether similar features are characteristics of NGAL. First, isolated normal myeloid bone marrow cells were incubated with NGAL for 6 and 24 hr and analyzed for apoptosis by annexin V binding and by propidium iodide labeling. We found no indication that NGAL induces significant apoptosis in myeloid cells. Second, a human sepsis model where normal volunteers were given endotoxin 2 ng/kg intravenously, showed no evidence that NGAL is an acute phase protein. The plasma level of NGAL reflected the number of circulating neutrophils and was completely different from the kinetics of C-reactive protein. We thus conclude that major differences exist between mouse and man with regards to the role of this lipocalin in myelopoiesis and inflammation.

Lipopolysaccharide-binding protein down-regulates the expression of interleukin-6 by human gingival fibroblast

BACKGROUND

Lipopolysaccharide-binding protein (LBP) participates in the interaction of lipopolysacchaide (LPS) with CD14 to modulate the expression of cytokines. Human gingival fibroblast may actively participate in LPS-induced immuno-inflammatory responses through CD14, toll-like receptor (TLR) superfamily, MD-2 and related adaptive proteins, leading to the expression of cytokines.

OBJECTIVES

The present in vitro study aimed to investigate the possible effect of LBP and E. coli LPS interaction on the expression of cellular LPS receptors and IL-6 by human gingival fibroblast.

METHODS

The mRNA expression of CD14, LBP, TLR-2, TLR-4, MD-2 and IL-6 in human gingival fibroblast explants was detected by reverse transcriptionpolymerase chain reaction (RT-PCR) in the presence or absence of E. coli LPS and recombinant human LBP (rhLBP), while IL-6 peptides were analyzed by ELISA and immunohistochemistry, respectively.

RESULTS

Human gingival fibroblast could constitutively express CD14, MD-2 and IL-6 mRNAs, but not TLR-2, TLR-4 and LBP mRNAs. E. coli LPS induced the messages expression of MD-2, TLR-2 and -4. The expression of both IL-6 message and peptide was up-regulated by E. coli LPS in a dose dependent manner. Whereas rhLBP could significantly down-regulate the expression of both mRNAs and peptides of CD14 and IL-6 but not MD-2 signals in the presence or absence of E. coli LPS. The up-regulated expression of TLR-2 and -4 by E. coli LPS no longer existed in the presence of rhLBP.

CONCLUSIONS

This study suggests that LBP may down-regulate the expression of IL-6 by human gingival fibroblast. Further studies are warranted to clarify the molecular mechanisms of LBP in regulation of cytokine expression by host cells and to elaborate the relevant clinical implications.

Potentiation of Lipopolysaccharide-Induced Chemokine and Adhesion Molecule Expression in Corneal Fibroblasts by Soluble CD14 or LPS-Binding Protein

PURPOSE

The detection of bacterial lipopolysaccharide (LPS) by human cells is facilitated by LPS-binding protein (LBP) and soluble (s)CD14. The effects of these proteins on chemokine release and adhesion molecule expression in cultured human corneal fibroblasts were examined.

METHODS

The release of chemokines into culture supernatants and the expression of the intercellular adhesion molecule (ICAM)-1 on the cell surface were determined by enzyme-linked immunosorbent assays. The intracellular abundance of chemokine and ICAM-1 mRNAs was quantitated by reverse transcription and real-time polymerase chain reaction analyses. The phosphorylation and degradation of IkappaB-alpha and the subcellular localization of NF-kappaB were examined by immunoblot and immunofluorescence analyses, respectively.

RESULTS

Neither sCD14 nor LBP alone affected the expression of chemokines or ICAM-1 in cultured human corneal fibroblasts. However, sCD14 or LBP enhanced the LPS-induced upregulation of ICAM-1 and the chemokines interleukin-8 and monocyte chemoattractant protein (MCP)-1 in these cells at the protein and mRNA levels. Combined stimulation with LPS and either sCD14 or LBP also induced the phosphorylation and degradation of IkappaB-alpha and the translocation of NF-kappaB from the cytoplasm to the nucleus of corneal fibroblasts.

CONCLUSIONS

LBP and sCD14 may play important roles in the defense of the cornea against bacterial infection, by facilitating the detection of LPS by corneal fibroblasts.

Normal rat hepatic stellate cells respond to endotoxin in LBP-independent manner to produce inhibitor(s) of DNA synthesis in hepatocytes

Endotoxin is implicated in the pathology of acute liver failure. The mechanisms of its actions on quiescent hepatic stellate cells (qHSCs) and their implications in hepatocyte injury are incompletely understood. We investigated effects of endotoxin (bacterial lipopolysaccharide; LPS) on qHSCs and subsequently on hepatocytes. After overnight culture following their isolation, qHSCs were incubated with or without endotoxin for 24 h. The cells and the culture supernatant were analyzed for cytokines and nitric oxide (NO) synthesis. The effects of qHSC-conditioned media on hepatocytes were then determined. LPS increased inducible NO synthase expression, stimulated NO synthesis, and inhibited DNA synthesis in qHSCs. qHSC-conditioned medium inhibited DNA synthesis in hepatocytes without affecting NO synthesis, while LPS (1-1,000 ng/ml)-conditioned qHSC medium stimulated NO synthesis and caused further inhibition of DNA synthesis and apoptosis. These effects of LPS were more pronounced when qHSCs were incubated with serum, but not with LPS-binding protein (LBP) although CD14 (a receptor for LPS-LBP complex) was found in qHSCs. LPS stimulated the synthesis of TNF-alpha, interleukin (IL)-6, and IL-1beta but not of TGF-beta in qHSCs. Individually or together, L-N(G)-monomethylarginine and antibodies to IL-1beta, IL-6, and TNF-alpha only partly reversed qHSC + LPS-conditioned medium-induced inhibition of DNA synthesis in hepatocytes. These results suggest that the effects of LPS on qHSCs are novel, occurring without the aid of LBP/CD14. They also indicate that other factors, in addition to NO, TGF-beta, TNF-alpha, IL-1beta, and IL-6 are involved in the mechanisms of the growth inhibitory effects of qHSCs on hepatocytes.

Altered Kupffer cell function in biliary obstruction

BACKGROUND

An altered Kupffer cell (KC) response is thought to be responsible for the characteristic phenotype observed after biliary obstruction: a phenotype marked by a defect in the hepatic reticuloendothelial system and a hypersensitivity to endotoxin. Few studies, however, have directly examined KC function. We have sought to define the specific alterations in function and phenotype that occur in the KC after biliary obstruction.

METHODS

KCs were isolated from female C57BL/6 mice 4 days after a sham or common bile duct ligation (CBDL) operation. Phagocytosis, oxidative burst potential, and intracellular bacterial killing were measured as markers of reticuloendothelial system function. The KC response to endotoxin was assessed by measuring tumor necrosis factor alpha and interleukin 6 levels in the media after stimulation with lipopolysaccharide (LPS) or with LPS plus LPS-binding protein (LBP).

RESULTS

CBDL KCs demonstrated a significant increase in phagocytic ability and significantly decreased baseline oxidative stress, compared with Shams. The oxidative burst potential, however, was equivalent or higher for CBDL KCs. CBDL KCs also demonstrated increased numbers of viable intracellular bacteria after infection; however, it is unclear if this finding represents impaired intracellular bacterial killing or increased phagocytosis of bacteria. With respect to the KC response to endotoxin, CBDL KCs were found to be less sensitive to the stimulatory effects of LPS alone but were exquisitely sensitive to the effects of LBP. LBP levels were found to be significantly elevated in CBDL animals, and CBDL KCs demonstrated a dose-dependent, exaggerated tumor necrosis factor alpha and interleukin 6 response to LPS administered with LBP.

CONCLUSIONS

KC function is clearly altered after biliary obstruction. Phagocytic ability is actually increased, although the ability of CBDL KCs to kill bacteria within the phagosome remains ill defined. CBDL KCs are exquisitely sensitive to the effects of LBP, and LBP levels are elevated after biliary obstruction. LBP may be responsible for the increased proinflammatory response observed after endotoxin challenge in animals with biliary obstruction.

A role for Rho and Rac in secretagogue-induced amylase release by pancreatic acini

The actin cytoskeleton has long been implicated in protein secretion. We investigated whether Rho and Rac, known regulators of the cytoskeleton, are involved in amylase secretion by mouse pancreatic acini. Secretagogues, including cholecystokinin (CCK) and the acetylcholine analog carbachol, increased the amount of GTP-bound RhoA and Rac1 and induced translocation from cytosol to a membrane fraction. Immunocytochemistry revealed the translocation of Rho and Rac within the apical region of the cell. Expression by means of adenoviral vectors of dominant-negative Rho (RhoN19), dominant-negative Rac (RacN17), and Clostridium Botulinum C3 exotoxin, which ADP ribosylates and inactivates Rho, significantly inhibited amylase secretion by CCK and carbachol; inhibiting both Rho and Rac resulted in a greater reduction. This inhibitory effect of RhoN19 on CCK-induced amylase secretion was apparent in both the early and late phases of secretion, whereas RacN17 was more potent on the late phase of secretion. None of these three affected the basal Ca2+or the peak intracellular Ca2+concentration stimulated by CCK. Latrunculin, a marine toxin that sequesters actin monomers, time-dependently decreased the total amount of filamentous actin (F-actin) and dose-dependently decreased secretion by secretagogues without affecting Ca2+signaling. These data suggest that Rho and Rac are both involved in CCK-induced amylase release in pancreatic acinar cell possibly through an effect on the actin cytoskeleton.

Lipopolysaccharide is transferred from high-density to low-density lipoproteins by lipopolysaccharide-binding protein and phospholipid transfer protein

Lipopolysaccharide (LPS), the major outer membrane component of gram-negative bacteria, is a potent endotoxin that triggers cytokine-mediated systemic inflammatory responses in the host. Plasma lipoproteins are capable of LPS sequestration, thereby attenuating the host response to infection, but ensuing dyslipidemia severely compromises this host defense mechanism. We have recently reported that Escherichia coli J5 and Re595 LPS chemotypes that contain relatively short O-antigen polysaccharide side chains are efficiently redistributed from high-density lipoproteins (HDL) to other lipoprotein subclasses in normal human whole blood (ex vivo). In this study, we examined the role of the acute-phase proteins LPS-binding protein (LBP) and phospholipid transfer protein (PLTP) in this process. By the use of isolated HDL containing fluorescent J5 LPS, the redistribution of endotoxin among the major lipoprotein subclasses in a model system was determined by gel permeation chromatography. The kinetics of LPS and lipid particle interactions were determined by using Biacore analysis. LBP and PLTP were found to transfer LPS from HDL predominantly to low-density lipoproteins (LDL), in a time- and dose-dependent manner, to induce remodeling of HDL into two subpopulations as a consequence of the LPS transfer and to enhance the steady-state association of LDL with HDL in a dose-dependent fashion. The presence of LPS on HDL further enhanced LBP-dependent interactions of LDL with HDL and increased the stability of the HDL-LDL complexes. We postulate that HDL remodeling induced by LBP- and PLTP-mediated LPS transfer may contribute to the plasma lipoprotein dyslipidemia characteristic of the acute-phase response to infection.

Lactoferrin works as a new LPS-binding protein in inflammatory activation of macrophages

Though lactoferrin (LF) is a glycoprotein that is involved in immunomodulation, its action mechanism has not been fully elucidated. Previous studies have suggested that lipopolysaccharide (LPS) activity is inhibited by direct binding between LPS and LF. However, here we show that when LPS and purified LF was mixed, and formed a complex (termed as LF-LPS), it was found to induce production of inflammatory mediators in macrophages to some extent, rather than inhibit LPS activity. Moreover, when macrophages were pretreated with LF-LPS, cells were rendered a tolerant state to LPS challenge. These macrophage-activating effects were mediated by Toll-like receptor 4 (TLR4)-NF-kappaB pathway. Comparative studies with C3H/HeN and C3H/HeJ mice demonstrated the strong dependency of the LF-LPS signal on TLR4. These findings suggest that the immunomodulatory properties of LF could be due, in part, to LPS binding.

Amelioration of ischemic acute renal injury by neutrophil gelatinase-associated lipocalin

Acute renal failure secondary to ischemic injury remains a common problem, with limited and unsatisfactory therapeutic options. Neutrophil gelatinase-associated lipocalin (NGAL) was recently shown to be one of the maximally induced genes early in the postischemic kidney. In this study, the role of NGAL in ischemic renal injury was explored. Intravenous administration of purified recombinant NGAL in mice resulted in a rapid uptake of the protein predominantly by proximal tubule cells. In an established murine model of renal ischemia-reperfusion injury, intravenous NGAL administered before, during, or after ischemia resulted in marked amelioration of the morphologic and functional consequences, as evidenced by a significant decrease in the histopathologic damage to tubules and in serum creatinine measurements. NGAL-treated animals also displayed a reduction in the number of apoptotic tubule cells and an increase in proliferating proximal tubule cells after ischemic injury. The results indicate that NGAL may represent a novel therapeutic intervention in ischemic acute renal failure, based at least in part on its ability to tilt the balance of tubule cell fate toward survival.

Lipopolysaccharide-binding protein modulates acetaminophen-induced liver injury in mice

Acetaminophen toxicity is the most common cause of acute liver failure in the United States and Europe. Although much is known about the metabolism of acetaminophen, many questions remain regarding the pathogenesis of liver injury. In this study, we examined the role of lipopolysaccharide-binding protein (LBP), a protein important in mediating cellular response to lipopolysaccharides, by using LBP wild-type and knockout (KO) mice. We found that LBP KO mice were protected from acetaminophen-induced hepatotoxicity. At 350 mg/kg of acetaminophen, LBP KO mice had significantly less liver injury and necrosis than wild-type mice. Repletion studies in LBP KO mice using an LBP-adenoviral construct resulted in significantly more hepatic injury and necrosis after acetaminophen exposure compared with mice receiving the control adenoviral construct. In conclusion, LBP KO mice are protected from toxicity with a decrease in hepatic necrosis following acetaminophen challenge. This suggests a novel role for LBP in modulating acetaminophen-induced liver injury. Supplementary material for this article can be found on the HEPATOLOGY website (http://interscience.wiley.com/jpages/O270-9139/suppmat/index.html).

Siderocalin (Lcn 2) Also Binds Carboxymycobactins, Potentially Defending against Mycobacterial Infections through Iron Sequestration

Siderocalin, a member of the lipocalin family of binding proteins, is found in neutrophil granules, uterine secretions, and at markedly elevated levels in serum and synovium during bacterial infection; it is also secreted from epithelial cells in response to inflammation or tumorigenesis. Identification of high-affinity ligands, bacterial catecholate-type siderophores (such as enterochelin), suggested a possible function for siderocalin: an antibacterial agent, complementing the general antimicrobial innate immune system iron-depletion strategy, sequestering iron as ferric siderophore complexes. Supporting this hypothesis, siderocalin is a potent bacteriostatic agent in vitro under iron-limiting conditions and, when knocked out, renders mice remarkably susceptible to bacterial infection. Here we show that siderocalin also binds soluble siderophores of mycobacteria, including M. tuberculosis: carboxymycobactins. Siderocalin employs a degenerate recognition mechanism to cross react with these dissimilar types of siderophores, broadening the potential utility of this innate immune defense.

LPS binding protein does not participate in the pharmacokinetics of E5564

E5564, a lipid A analogue, is a potent antagonist of lipopolysaccharide (LPS). Clinically, E5564 was developed as a possible therapy for treatment of sepsis and septic shock. Surface plasmon resonance (SPR) analysis indicates that E5564 binds to LPS binding protein (LBP), in a manner similar to LPS. Gel-filtration radioactive chromatograms of [(14)C]-E5564 in plasma revealed that E5564 initially distributes to the lipoprotein fractions, separated from high-density lipoprotein (HDL); the bound fraction is then released and binds to HDL. Similar results were obtained by heparin-manganese precipitation. At doses of E5564 relevant to its clinical use (i.e. 6 microg/ml), antibodies against LBP did not influence either the distribution of E5564 to non-HDL lipoprotein fractions or the transfer of E5564 from non-HDLs to HDL. Under these conditions, transfer of E5564 to HDL occurs similarly in the plasma of LBP knockout (KO) mice as in the plasma from wild-type mice. In addition, plasma clearance of E5564 in LBP KO mice is similar to that of wildtype mice. Thus, LBP binds E5564 in a manner similar to LPS, but does not play a role in E5564 redistribution/binding to lipoprotein and plasma clearance.

Interleukin-6 is responsible for drug resistance and anti-apoptotic effects in prostatic cancer cells

BACKGROUND

Interleukin (IL)-6-mediated anti-apoptotic effects and drug-resistance mechanisms in prostate cancer cells were investigated.

METHODS

IL-6 levels of PC-3 and LNCaP cells were studied by using ELISA. Protective effects of IL-6 on cytotoxic agent-induced apoptosis were studied by exogenous IL-6 in serum-starved PC-3 cells and by anti-sense IL-6 strategy. Western blotting and reverse transcription-polymerase chain reaction (RT-PCR) were used to determine IL-6 effects on Bcl-2 family proteins. Tetracycline-regulated Bcl-xL expression system and dominant negative STAT3 transfectants were used to study IL-6 signaling pathways and its anti-apoptosis effects.

RESULTS

Exogenous IL-6 and anti-sense IL-6 oligonucleotide treatment conferred resistance to cytotoxic agent-induced apoptosis. Among Bcl-2 family proteins, only Bcl-xL was evidently increased by IL-6 stimulation. The anti-apoptotic effect of IL-6 can be significantly attenuated by anti-sense bcl-xL transfection and partially abrogated in dominant negative STAT3 transfectants.

CONCLUSIONS

IL-6 is a survival factor against cytotoxic agent-induced apoptosis through both STAT3 and bcl-xL pathways in prostate cancer cells.

Sensing Environmental Lipids by Dendritic Cell Modulates Its Function

Because of its oxidative modification during the acute-phase response to an aggression, low density lipoprotein (LDL) can be regarded as a source of lipid mediators that can act both to promote and inhibit inflammation. This can be exemplified by the production of anti-inflammatory oxidized fatty acids and proinflammatory lysophosphatidylcholine (LPC) during LDL oxidation. We have shown previously that oxidized LDL (oxLDL) plays an active role at the interface between innate and adaptive immunity by delivering instructive molecules such as LPC, which promotes mature dendritic cell (DC) generation from differentiating monocytes. It is shown in this study that LPC affects the signaling pathway of peroxisome proliferator-activated receptors (PPARs). LPC-induced DC maturation is associated with complete inhibition of PPARgamma activity and up-regulation of the activity of an uncharacterized nuclear receptor that bind peroxisome proliferator response element. Oxidized fatty acids generated during LDL oxidation are natural ligands for PPARgamma and inhibit oxLDL- and LPC-induced maturation. Inhibition experiments with synthetic PPARgamma ligands suggested a PPARgamma-dependent and independent effect of LPC on DC maturation. Therefore, the relative amount of oxidized fatty acids and LPC influences the immunological functions of oxLDL on DC, in part by regulating the PPAR pathway. By sensing the biochemical composition of lipoprotein particles, the innate immune system may thus identify various endogenous signals that influence the immune response during the acute-phase reaction. The therapeutic emulsion intralipid also blocks LPC action on PPAR activity and DC maturation. Intralipid may thus be an alternative therapeutic strategy for some chronic inflammatory diseases.

Mouse lipocalin as an enhancer of spermatozoa motility

The 24p3 protein is a 25 kDa glycoprotein that is secreted into the uterine fluid during the proestrous phase of mice. We assessed the effects on spermatozoa motility and on the functions of mouse spermatozoa using the computer-assisted sperm analysis method, cytochemical staining and detection of the protein tyrosine phosphorylation pattern. Compared with the control cells, sperm motility was stimulated by the addition of 24p3 protein into the medium. Introducing 24p3 protein enhanced progressive motility but did not promote the appearance of hyperactivated movement. The presence of 24p3 protein in the medium did not allow the cells to undergo the capacitated protein tyrosine phosphorylation pattern and acrosome reaction. The tyrosine phosphorylation pattern shows phosphoproteins in the range of Mr 50,000-106,000 correlated with the sperm progressive motility after the addition of 24p3 protein into the medium. Using flow cytometry, we assessed the changes in the intracellular pH and measured the intracellular cAMP concentration with an immunodetection kit. The results indicated that the elevation in intracellular pH from 6.67 to 6.89, increase of intracellular cAMP accumulation, and protein tyrosine phosphorylation might be the factors in enhancement of sperm motility as the 24p3 protein bound to the spermatozoa. The 24p3 protein may have a role in regulating flagellar motility.

Platelet-derived endothelial cell growth factor mediates Rho-associated coiled-coil domain kinase messenger RNA expression and promotes cell motility

BACKGROUND

Platelet-derived endothelial cell growth factor (PD-ECGF), whose expression is increased in several cancers, is an endothelial cell mitogen and has chemotactic activity in vitro and angiogenic activity in vivo. Tumors with high PD-ECGF expression tend to have frequent lymph node metastasis and are associated with poor outcome.

METHODS

We screened genes transduced by PD-ECGF transfection to the colon cancer cell line DLD-1 by using a complementary DNA microarray. Cell motility was evaluated by in vitro migration assay. Actin fiber polymerization was visualized by immunofluorescent detection of phalloidin.

RESULTS

Rho-associated coiled-coil domain kinase (ROCK1) was found to be significantly overexpressed in PD-ECGF transfectants compared with mock cells. PD-ECGF transfectants showed higher cell motility than mock cells. The parental cell, DLD-1, with recombinant PD-ECGF showed higher cell motility than that without recombinant PD-ECGF, in which motility was blocked by the neutralizing antibody of PD-ECGF or Y-27632, a specific inhibitor of ROCK1. Moreover, the actin fiber polymerization, which is a marker of activation of ROCK1, was higher in PD-ECGF transfectants than in mock cells.

CONCLUSIONS

PD-ECGF expression may be associated with cancer cell migration via activation of ROCK1. This may explain one mechanism by which tumors with high expression of PD-ECGF show aggressive behavior.

[Acute-phase reaction]

The systemic changes induced by inflammation have been referred as the acute-phase response. The changes in the concentrations of acute-phase proteins are due largely to changes in their production by hepatocytes induced by pro-inflammatory cytokines. Because of its specificity, sensibility and short half-life, C-reactive protein is the most useful indicator among all the acute-phase proteins. The clinical strategy to deal with an acute-phase response is to search the aetiology: infections, neoplasms, auto-immune and allergic diseases. The treatment of an acute-phase response is the treatment of its aetiology.

The neutrophil lipocalin NGAL is a bacteriostatic agent that interferes with siderophore-mediated iron acquisition

First identified as a neutrophil granule component, neutrophil gelatinase-associated lipocalin (NGAL; also called human neutrophil lipocalin, 24p3, uterocalin, or neu-related lipocalin) is a member of the lipocalin family of binding proteins. Putative NGAL ligands, including neutrophil chemotactic agents such as N-formylated tripeptides, have all been refuted by recent biochemical and structural results. NGAL has subsequently been implicated in diverse cellular processes, but without a characterized ligand, the molecular basis of these functions remained mysterious. Here we report that NGAL tightly binds bacterial catecholate-type ferric siderophores through a cyclically permuted, hybrid electrostatic/cation-pi interaction and is a potent bacteriostatic agent in iron-limiting conditions. We therefore propose that NGAL participates in the antibacterial iron depletion strategy of the innate immune system.

Inhibition of apoptosis by ATFx: a novel role for a member of the ATF/CREB family of mammalian bZIP transcription factors

The mammalian ATF/CREB family of transcription factors comprises a large group of basic-region leucine zipper (bZIP) proteins whose members mediate diverse transcriptional regulatory functions. Here we report that expression of a specific mouse ATF gene, ATFx, is down-regulated in a variety of cells undergoing apoptosis following growth factor deprivation. When stably expressed in an interleukin 3 (IL-3)-dependent cell line, ATFx suppresses apoptosis resulting from cytokine deprivation. Conversely, a dominant-negative ATFx mutant induces apoptosis of cells cultured in the presence of growth factors. We also show that 24p3, a secreted lipocalin that induces apoptosis when added to hematopoietic cells, represses ATFx expression. However, constitutive expression of ATFx renders cells resistant to 24p3-mediated apoptosis. Collectively, our results indicate that ATFx is an anti-apoptotic factor, a novel role for an ATF protein.

Production of granulocyte colony-stimulating factor in the nonspecific acute phase response enhances host resistance to bacterial infection

Mice mounting an acute phase response, induced by sterile inflammation after a single s.c. injection of casein 24 h beforehand, were remarkably protected against lethal infection with Gram-positive or Gram-negative bacteria. This was associated with enhanced early clearance of bacteremia, greater phagocytosis and oxidative burst responses by neutrophils, and enhanced recruitment of neutrophils into tissues compared with control, nonacute phase mice. Casein-induced inflammation was also associated with increased concentrations of G-CSF in serum, and administration of neutralizing Ab to this cytokine completely abrogated protection against Escherichia coli infection after casein pretreatment. Injection of recombinant murine G-CSF between 3 and 24 h before infection conferred the same protection as casein injection. In contrast, the casein-induced acute phase response affected neither serum values of TNF-alpha, IL-1 beta, or IL-6 after E. coli infection nor susceptibility to LPS toxicity. Furthermore, protection against infection was unaffected in IL-1R knockout mice, which have deficient acute phase plasma protein responses, or after nonspecific inhibition of acute phase protein synthesis by D-galactosamine or specific depletion of complement C3 by cobra venom factor. Increased production of G-CSF in the acute phase response is thus a key physiological component of host defense, and pretreatment with G-CSF to prevent bacterial infection in at-risk patients now merits further study, especially in view of increasing bacterial resistance to antibiotics.

Induction of acute phase response genes in keratinocytes following exposure to oligodeoxynucleotides

Keratinocytes have the ability to take up oligodeoxynucleotides (ODN) and plasmid DNA probably by receptor-mediated endocytosis. Despite the use of DNA for antisense and gene therapy little is known about the regulation of genes following exposure to nucleic acids. To systematically identify gene regulation in keratinocytes upon exposure to ODN we screened human cytokine DNA arrays containing 383 different genes and found interleukin (IL) 1alpha, IL-1beta, integrin-beta(1), alpha-tubulin, and follistatin highly induced, while most genes were unaffected. The time course and concentration dependence for IL-1alpha and follistatin expression were analyzed by standard northern blot technique. ODN of different length and sequence induced comparable amounts of IL-1alpha and follistatin. Their induction was independent of negative charge and of several proinflammatory compounds such as lipopolysaccharides, IL-1beta, and interferon-gamma but was partly inhibited by activin A. In summary, our study revealed several genes of the acute phase protein family that are induced in a non-sequence-specific manner following the exposure of normal human keratinocytes to ODN. Therefore it is tempting to speculate that upon internalization ODN bind to an intracellular receptor (e.g., Toll-like receptor 9) which mediates signaling.

The tumor vascular targeting agent combretastatin A-4-phosphate induces reorganization of the actin cytoskeleton and early membrane blebbing in human endothelial cells

Combretastatin A-4-phosphate (CA-4-P) is a tubulin-binding compound currently in clinical trial as a tumor vascular-targeting agent. In endothelial cells, CA-4-P is known to cause microtubule depolymerization, but little is known about its subsequent effects on cell morphology and function. Here, we demonstrate that within minutes of endothelial cell exposure to CA-4-P, myosin light chain (MLC) was phosphorylated, leading to actinomyosin contractility, assembly of actin stress fibers, and formation of focal adhesions. These cytoskeletal alterations appeared to be a consequence of Rho activation, as they were abolished by either the Rho inhibitor C3 exoenzyme or Rho-kinase inhibitor Y-27632. In response to CA-4-P, some cells rapidly assumed a blebbing morphology in which F-actin accumulated around surface blebs, stress fibers misassembled into a spherical network surrounding the cytoplasm, and focal adhesions appeared malformed. Blebbing was associated with decreased cell viability and could be inhibited by Rho/Rho-kinase inhibitors or by blocking the CA-4-P-mediated activation of stress-activated protein kinase-2/p38. The extracellular-regulated kinases 1 and 2 (ERK-1/2) were shown to protect against blebbing since blebbing was attenuated on ERK-1/2 stimulation and was up-regulated by specific inhibition of ERK-1/2 activation. The use of MLC kinase (MLCK) and myosin adenosine triphosphatase inhibitors led us to propose a role for MLCK and myosin activity independent of MLC phosphorylation in regulating the blebbing process. CA-4-P-mediated contractility and blebbing were associated with a Rho-dependent increase in monolayer permeability to dextrans, suggesting that such functional changes may be important in the rapid response of the tumor endothelium to CA-4-P in vivo.

Lipopolysaccharide-binding protein increases toll-like receptor 4-dependent activation by nontypeable Haemophilus influenzae

Nontypeable Haemophilus influenzae (NTHi) is a common cause of respiratory tract infections. This study investigated the ability of NTHi to bind lipopolysaccharide-binding protein (LBP) derived from respiratory epithelial cells and the subsequent stimulation of transfected cells expressing membrane-bound CD14 and toll-like receptor 2 (TLR2) or TLR4. In the absence of LBP, NTHi at high concentrations (100 bacteria/epithelial cell) were required to induce signals through TLR2 and TLR4. Flow cytometry showed that NTHi in the stationary phase bound more LBP than did log-phase bacteria. Of interest, as few as 1 LBP-bearing bacterium/cell induced strong signaling through TLR4. In contrast, LBP bound to NTHi did not promote any increased signaling mediated by TLR2, compared with NTHi without LBP. These data suggest that, upon NTHi infection, low numbers of bacteria binding LBP may activate TLR4-bearing cells, such as alveolar macrophages, and consequently induce an inflammatory response.

Mitogenic effect of lipoproteins on human vascular smooth muscle cells: the impact of hydrolysis by gr II A phospholipase A(2)

Multifactorial interaction among lipoproteins, vascular wall cells, and inflammatory mediators has been recognized as the basis of atherogenesis. In the arterial wall high-density lipoprotein (HDL) and human secretory phospholipase A(2) (sPLA(2)) colocalize with vascular smooth muscle cells and concentrate in the atherosclerotic lesions. It has been shown that gr IIA sPLA(2) hydrolyzes lipoproteins, altering their structure and releasing active agents such as lyso-phosphatidylcholine (PtdCho) and free fatty acids. We investigated the impact of normal HDL(3) (NHDL(3)), acute phase HDL(3) (APHDL(3)), and low-density lipoprotein (LDL), both unhydrolyzed and sPLA(2)-hydrolyzed, and some products of hydrolysis, such as lyso-PtdCho, oleic and linoleic acid, on [(3)H] thymidine incorporation by DNA of cultured human vascular smooth muscle cells (VSMC). NHDL(3) markedly enhanced mitogenic activity of VSMC in a dose- and time-dependent manner. Doubling of thymidine incorporation was usually achieved by 40 microg/ml of NHDL(3) after 4 hours of incubation. APHDL(3) had invariably a stronger inducing effect on the mitogenic activity than NHDL(3); 40 microg/ml more than tripled [(3)H] thymidine incorporation after 4 hours of incubation. NHDL(3) preincubated with human apo serum amyloid A apolipoprotein-induced higher mitogenic activity in VSMC than NHDL(3) alone. Hydrolysis of NHDL(3), APHDL(3), or LDL by gr IIA sPLA(2) markedly enhanced mitogenic activity of VSMC as compared with unhydrolyzed lipoproteins. sPLA(2) concentrations that can be found in atherosclerotic vascular walls markedly enhanced lipoprotein-induced mitogenic activity of VSMC. sPLA(2) per se did not affect thymidine incorporation and VSMC did not release sPLA(2) into the medium. There was no evidence for hydrolysis of the wall of VSMC by gr IIA sPLA(2). The presence of the products of hydrolysis of lipoproteins such as oleic and linoleic acids and lyso-PtdCho or their combinations with NHDL(3) explains in part markedly enhanced mitogenic activity of VSMC. It is conceivable that sPLA(2,) which is known to colocalize with lipoproteins in the vascular wall in the domain of VSMC, is capable of induction of the mitogenic activity in these cells in vivo and should be considered as a proatherogenic enzyme.

Fetuin, a negative acute phase protein, attenuates TNF synthesis and the innate inflammatory response to carrageenan

Activation of the innate immune system, even by relatively innocuous stimuli, stimulates the release of cytokines (e.g. TNF) that can injure or kill the host. To maintain homeostasis, mammals have evolved a counter-regulatory response that suppresses the development of excessively robust inflammation. Fetuin, a 66-kD negative acute phase glycoprotein, was first identified in 1944. We recently discovered an anti-inflammatory role for fetuin, because it suppressed the release of TNF from lipopolysaccharide- (LPS) stimulated macrophages. Here the anti-inflammatory effects of fetuin were studied in vivo in an LPS-independent model of acute inflammation caused by administration of carrageenan. Administration of fetuin (5-500 mg/kg intraperitoneally) dose-dependently attenuated the development of paw edema as compared to either asialofetuin (500 mg/kg) or bovine albumin (500 mg/kg). TNF production in the carrageenan-injected paws was significantly inhibited by administration of fetuin (586+/-98 pg TNF/paw) as compared to either asialofetuin (1018+/-186 pg TNF/paw) or saline (1,005+/-172 pg TNF/paw). When specific anti-fetuin IgG was administered into the paw prior to the application of carrageenan, the development of edema formation was significantly increased as compared to irrelevant IgG, indicating that endogenous fetuin normally attenuates the inflammatory response. These results now reveal a previously unrecognized anti-inflammatory role of fetuin in counter-regulating the innate immune response, and suggest that it may be possible to use fetuin as an experimental anti-inflammatory agent.

Pancreatitis associated protein I (PAP-I) alters adhesion and motility of human melanocytes and melanoma cells

Pancreatitis associated protein I is a secretory stress protein first characterized in pancreas during pancreatitis but also expressed in several tissues including hepatic, gastric, and colon cancer. Its concentration in serum can be significant. The relationship of pancreatitis associated protein I to skin cancers was investigated in normal melanocytes, melanoma tumors, and melanoma cell lines. None of them expressed pancreatitis associated protein I, even after stress induction. Adenovirus-mediated pancreatitis associated protein I expression, however, reduced cell adhesion to laminin-1 and fibronectin with a loss of integrin participation. Pancreatitis associated protein I expression stimulated haptotactic and directed migrations of some melanoma cells, but only directed migration was activated in normal melanocytes. Importantly, directed migration and spreading on fibronectin of the responsive melanoma cells were also enhanced when purified rat pancreatitis associated protein I was added to the culture medium of noninfected cells. This indicates that effects in infected cells were elicited by pancreatitis associated protein I after its secretion. Exogenous pancreatitis associated protein I can therefore modify the adhesion and motility of normal and transformed melanocytes, suggesting a potential interaction with melanoma invasivity.

Cytokine hypothesis of overtraining: a physiological adaptation to excessive stress?

Overtraining syndrome (OTS) is a condition wherein an athlete is training excessively, yet performance deteriorates. This is usually accompanied by mood/behavior changes and a variety of biochemical and physiological alterations. Presently, there is no global hypothesis to account for OTS. The present paper will attempt to provide a unifying paradigm that will integrate previous research under the rubric of the cytokine hypothesis of overtraining. It is argued that high volume/intensity training, with insufficient rest, will produce muscle and/or skeletal and/or joint trauma. Circulating monocytes are then activated by injury-related cytokines, and in turn produce large quantities of proinflammatory IL-1beta, and/or IL-6, and/or TNF-alpha, producing systemic inflammation. Elevated circulating cytokines then co-ordinate the whole-body response by: a) communicating with the CNS and inducing a set of behaviors referred to as "sickness" behavior, which involves mood and behavior changes that support resolution of systemic inflammation: b) adjusting liver function, to support the up-regulation of gluconeogenesis, as well as de novo synthesis of acute phase proteins, and a concomitant hypercatabolic state; and c) impacting on immune function. Theoretically, OTS is viewed as the third stage of Selye's general adaptation syndrome, with the focus being on recovery/survival, and not adaptation, and is deemed to be "protective," occurring in response to excessive physical/physiological stress. Recommendations are made for potential markers of OTS, based on a systemic inflammatory condition.

Lipopolysaccharide potentiates the effect of hepatocyte growth factor on hepatocyte replication in rats by augmenting AP-1 activity

The liver regenerates by replication of differentiated hepatocytes after damage or removal of part of the liver. Although several growth factors and signaling pathways are activated during regeneration, it is unclear as to which of these are essential for hepatocyte replication. We show here that low- (1 mg/kg) and high- (10 mg/kg) dose hepatocyte growth factor (HGF) induced replication of 2.1% and 11.1% of hepatocytes in rats, respectively. Lipopolysaccharide (LPS), an inducer of the acute phase response, augmented hepatocyte replication in response to low- and high-dose HGF by 4- and 2-fold, respectively. HGF alone induced moderate levels of c-Jun-N-terminal kinase (JNK) and p44/p42 mitogen-activated protein kinase (MAPK), resulting in moderate levels of AP-1-DNA binding activity. The combination of LPS + HGF increased JNK and AP-1-DNA binding activity more than levels seen with LPS or HGF alone. The activation of Stat3 that was observed after administration of LPS + HGF, but not HGF alone, could contribute to increased transcription of AP-1 components. Because phosphorylation of the c-Jun component of AP-1 by JNK increases its ability to activate transcription, the AP-1 in hepatocytes from animals treated with LPS + HGF may be more active than in rats treated with LPS or HGF alone. LPS may contribute to hepatocyte replication by potentiating the effect of HGF on the activation of both AP-1-DNA binding and transcriptional activity.

Activation of caspases in lethal experimental hepatitis and prevention by acute phase proteins

Lethal hepatitis can be induced by an agonistic anti-Fas Ab in normal mice or by TNF in mice sensitized to d -(+)-galactosamine or actinomycin D. In all three models, we found that apoptosis of hepatocytes is an early and necessary step to cause lethality. In the three models, we observed activation of the major executioner caspases-3 and -7. Two acute-phase proteins, alpha1-acid glycoprotein and alpha1-antitrypsin, differentially prevent lethality: alpha1-acid glycoprotein protects in both TNF models and not in the anti-Fas model, while alpha1-antitrypsin confers protection in the TNF/d -(+)-galactosamine model only. The protection is inversely correlated with activation of caspase-3 and caspase-7. The data suggest that activation of caspase-3 and -7 is essential in the in vivo induction of apoptosis leading to lethal hepatitis and that acute phase proteins are powerful inhibitors of apoptosis and caspase activation. Furthermore, Bcl-2 transgenic mice, expressing Bcl-2 specifically in hepatocytes, are protected against a lethal challenge with anti-Fas or with TNF/d -(+)-galactosamine, but not against TNF/actinomycin D. The acute-phase proteins might constitute an inducible anti-apoptotic protective system, which in pathology or disturbed homeostasis prevents excessive apoptosis.

Pancreatitis-associated protein protects the lung from leukocyte-induced injury

BACKGROUND

Severe pancreatitis is often complicated by shock and acute lung failure. Little is known about the pathophysiologic impact of the 16.6-kD lectine, named pancreatitis-associated protein (PAP), which is expressed during pancreatitis and which reduces mortality in a rat model with severe pancreatitis. Therefore, the aim of this study was to investigate the effects of PAP on the pulmonary vasculature after leukocyte activation with N-formyl-Met-Leu-Phe (fMLP).

METHODS

The experiments were performed in buffer-perfused isolated rabbit lungs. Mean pulmonary artery pressure, weight gain, and thromboxane A2 synthesis of the lungs were monitored. PAP was obtained by affinity chromatography of pancreas juice from pancreatitic rats. The authors tested whether treatment with PAP (260 microg/l, n = 9; or 500 microg/l, n = 6) before fMLP injection (10(-6) M) influences mean pulmonary artery pressure and edema formation. Lungs that were treated only with fMLP (n = 6) served as controls. Additional experiments in which PAP was applied were performed to study whether PAP (260 microg/l, n = 3; 500 microg/l, n = 3; 1,000 microg/l, n = 3) itself effects lung vasculature.

RESULTS

Application of fMLP resulted in an increase of mean pulmonary artery pressure (+/- SD) from 8 +/- 2 mmHg up to 26 +/-13 mmHg (P < 0.01) at a flow of 150 ml/min. Pretreatment with PAP reduced the peak pressure developed after fMLP to 15 +/- 7 mmHg (PAP 260 microg/l; P < 0.05) and to 9 +/- 4 mmHg (PAP 500 microg/l), respectively. In addition, the fMLP-induced lung weight gain of 9 +/- 7 g in the controls was prevented by pretreatment with PAP after 150 min in either concentration. In parallel to the attenuated pressure increase, thromboxane A2 release was significantly suppressed in the 260-microg/l (200 +/- 220 pmol x ml(-1) x min(-1); P < 0.01) and 500-microg/l (285 +/- 70 pmol x m(-1) x min(-1); P < 0.05) PAP groups compared with controls (1,138 +/- 800 pmol x ml(-1) x mi(-1)). Treatment with PAP alone in either concentration did not induce any changes in mean pulmonary artery pressure, weight gain, or thromboxane A2 release.

CONCLUSION

Clinically relevant concentrations of PAP prevented fMLP-induced vasoconstriction and edema formation in the lung. These findings point toward a protective effect of PAP on polymorphonuclear neutrophil leukocyte-mediated lung injury.