The coupling between irradiance, growth, photosynthesis and prymnesin cell quota and production in two strains of the bloom-forming haptophyte, Prymnesium parvum

Prymnesium parvum causes harmful algal blooms worldwide that are often associated with massive fish-kills and subsequent economic losses. Most of our knowledge of the toxicity of P. parvum derives from bioassays since methods for the identification and quantification of their toxins have been lacking. Recently, a quantitation method was developed for the causative lytic toxins, the prymnesins. Here, we for the first time present data on the influence of irradiance on cellular content and production of prymnesins under nutrient replete conditions in two P. parvum strains, which both produce B-type prymnesins. Large differences were observed between the two strains with regard to the influence of irradiance on prymnesin cell quota and production rates. At the highest irradiance level (550 µmol photons m-2 s-1), the cellular prymnesin quota was thirty times higher in strain K-0081 strain than in K-0374. The cellular prymnesin quota and production rates were closely linked to rates of growth and photosynthesis in strain K-0081, while this was not the case for K-0374. Yet, growth rate did explain the differences in prymnesin quota in the two strains. Consequently, the maximum prymnesin production rate (414 attomol cell-1 d-1) was only about three times higher in strain K-0081 than in K-0374, and revealed an optimum at the same irradiance of 200 µmol photons m-2 s-1 in both strains. At low irradiance levels, the difference in production rates between both strains became smaller, with 41 and 49 attomol cell-1 d-1 for K-0081 and K-0374, respectively. The carbon content of prymnesins made up for ∼3% and <1% of the total cellular carbon content in strains K-0081 and K-0374, respectively. The fraction of extracellular dissolved prymnesins was measured for strain K-0081, where it accounted for 14-30% of total prymnesin concentration in the cultures, irrespective of irradiance. The concentrations of prymnesins released to the water by the K-0081 strain were not significantly influenced by irradiance. Overall, we observed comparable responses in growth and photosynthesis of both tested strains toward changes in irradiance. However, the effects of irradiance on prymnesin quota and production rates were remarkably different between the two strains.

Modified Lipids and Lipoproteins in Chronic Kidney Disease: A New Class of Uremic Toxins

Chronic kidney disease (CKD) is associated with an enhanced oxidative stress and deep modifications in lipid and lipoprotein metabolism. First, many oxidized lipids accumulate in CKD and were shown to exert toxic effects on cells and tissues. These lipids are known to interfere with many cell functions and to be pro-apoptotic and pro-inflammatory, especially in the cardiovascular system. Some, like F2-isoprostanes, are directly correlated with CKD progression. Their accumulation, added to their noxious effects, rendered their nomination as uremic toxins credible. Similarly, lipoproteins are deeply altered by CKD modifications, either in their metabolism or composition. These impairments lead to impaired effects of HDL on their normal effectors and may strongly participate in accelerated atherosclerosis and failure of statins in end-stage renal disease patients. This review describes the impact of oxidized lipids and other modifications in the natural history of CKD and its complications. Moreover, this review focuses on the modifications of lipoproteins and their impact on the emergence of cardiovascular diseases in CKD as well as the appropriateness of considering them as actual mediators of uremic toxicity.

The effects of orally administered Beta-glucan on innate immune responses in humans, a randomized open-label intervention pilot-study

Rationale

To prevent or combat infection, increasing the effectiveness of the immune response is highly desirable, especially in case of compromised immune system function. However, immunostimulatory therapies are scarce, expensive, and often have unwanted side-effects. β-glucans have been shown to exert immunostimulatory effects in vitro and in vivo in experimental animal models. Oral β-glucan is inexpensive and well-tolerated, and therefore may represent a promising immunostimulatory compound for human use.

Methods

We performed a randomized open-label intervention pilot-study in 15 healthy male volunteers. Subjects were randomized to either the β -glucan (n = 10) or the control group (n = 5). Subjects in the β-glucan group ingested β-glucan 1000 mg once daily for 7 days. Blood was sampled at various time-points to determine β-glucan serum levels, perform ex vivo stimulation of leukocytes, and analyze microbicidal activity.

Results

β-glucan was barely detectable in serum of volunteers at all time-points. Furthermore, neither cytokine production nor microbicidal activity of leukocytes were affected by orally administered β-glucan.

Conclusion

The present study does not support the use of oral β-glucan to enhance innate immune responses in humans.

Trial Registration

ClinicalTrials.gov NCT01727895

Mycosubtilin and surfactin are efficient, low ecotoxicity molecules for the biocontrol of lettuce downy mildew

The use of surfactin and mycosubtilin as an eco-friendly alternative to control lettuce downy mildew caused by the obligate pathogen Bremia lactucae was investigated. Preliminary ecotoxicity evaluations obtained from three different tests revealed the rather low toxicity of these lipopeptides separately or in combination. The EC50 (concentration estimated to cause a 50 % response by the exposed test organisms) was about 100 mg L(-1) in Microtox assays and 6 mg L(-1) in Daphnia magna immobilization tests for mycosubtilin and 125 mg L(-1) and 25 mg L(-1) for surfactin, respectively. The toxicity of the mixture mycosubtilin/surfactin (1:1, w/w) was close to that obtained with mycosubtilin alone. In addition, the very low phytotoxic effect of these lipopeptides has been observed on germination and root growth of garden cress Lepidium sativum L. While a surfactin treatment did not influence the development of B. lactucae on lettuce plantlets, treatment with 100 mg L(-1) of mycosubtilin produced about seven times more healthy plantlets than the control samples, indicating that mycosubtilin strongly reduced the development of B. lactucae. The mixture mycosubtilin/surfactin (50:50 mg L(-1)) gave the same result on B. lactucae development as 100 mg L(-1) of mycosubtilin. The results of ecotoxicity as well as those obtained in biocontrol experiments indicated that the presence of surfactin enhances the biological activities of mycosubtilin. Mycosubtilin and surfactin were thus found to be efficient compounds against lettuce downy mildew, with low toxicity compared to the toxicity values of chemical pesticides. This is the first time that Bacillus lipopeptides have been tested in vivo against an obligate pathogen and that ecotoxic values have been given for surfactin and mycosubtilin.

Yuwen02f1 suppresses LPS-induced endotoxemia and adjuvant-induced arthritis primarily through blockade of ROS formation, NFkB and MAPK activation

Phagocytes release inflammatory mediators to defense harmful stimuli upon bacterial invasion, however, excessive inflammatory reaction leads to tissue damage and manifestation of pathological states. Therefore, targeting on uncontrolled inflammation seems feasible to control numerous inflammation-associated diseases. Under the drug screening process of synthetic diphenylpyrazole derivatives, we discovered compound yuwen02f1 possesses anti-inflammatory effects in decreasing the release of pro-inflammatory cytokines including TNFα and IL-6, nitric oxide, reactive oxygen species (ROS) as well as inhibiting migration of LPS-stimulated phagocytes. In addition, we observed that the molecular mechanism of yuwen02f1-mediated anti-inflammation is associated with decreasing phosphorylation of MAPK molecules including ERK1/2, JNK and p38, and attenuating translocation of p47(phox) and p67(phox) to the cell membrane. Yuwen02f1 also reverses IκBα degradation and attenuates the expression of NFκB-related downstream inducible enzymes like iNOS and COX-2. Furthermore, we found that yuwen02f1 attenuates some pathological syndromes of LPS-induced sepsis and adjuvant-induced arthritis in mice, as evidenced by decreasing the cytokine production, reversing thrombocytopenic syndrome, protecting the mice from tissue injury in septic mice, and attenuating paw edema in arthritic mice as well. These results suggest that yuwen02f1 is a potential anti-inflammatory agent for alleviating syndromes of acute and chronic inflammatory diseases as evidenced by attenuating the generation of cytokines and down-regulating the expression of iNOS and COX-2 through the blockade of ROS generation and NADPH oxidase, NFκB and MAPK activation pathways in LPS-stimulated phagocytes.

Prymnesins: toxic metabolites of the golden alga, Prymnesium parvum Carter (Haptophyta)

Increasingly over the past century, seasonal fish kills associated with toxic blooms of Prymnesium parvum have devastated aquaculture and native fish, shellfish, and mollusk populations worldwide. Protracted blooms of P. parvum can result in major disturbances to the local ecology and extensive monetary losses. Toxicity of this alga is attributed to a collection of compounds known as prymnesins, which exhibit potent cytotoxic, hemolytic, neurotoxic and ichthyotoxic effects. These secondary metabolites are especially damaging to gill-breathing organisms and they are believed to interact directly with plasma membranes, compromising integrity by permitting ion leakage. Several factors appear to function in the activation and potency of prymnesins including salinity, pH, ion availability, and growth phase. Prymnesins may function as defense compounds to prevent herbivory and some investigations suggest that they have allelopathic roles. Since the last extensive review was published, two prymnesins have been chemically characterized and ongoing investigations are aimed at the purification and analysis of numerous other toxic metabolites from this alga. More information is needed to unravel the mechanisms of prymnesin synthesis and the significance of these metabolites. Such work should greatly improve our limited understanding of the physiology and biochemistry of P. parvum and how to mitigate its blooms.

Tolerization with BLP down-regulates HMGB1-a critical mediator of sepsis-related lethality

Tolerization with bacterial lipoprotein (BLP) affords a significant survival benefit in sepsis. Given that high mobility group box protein-1 (HMGB1) is a recognized mediator of sepsis-related lethality, we determined if tolerization with BLP leads to alterations in HMGB1. In vitro, BLP tolerization led to a reduction in HMGB1 gene transcription. This was mirrored at the protein level, as HMGB1 protein expression and release were reduced significantly in BLP-tolerized human THP-1 monocytic cells. BLP tolerance in vivo led to a highly significant, long-term survival benefit following challenge with lethal dose BLP in C57BL/6 mice. This was associated with an attenuation of HMGB1 release into the circulation, as evidenced by negligible serum HMGB1 levels in BLP-tolerized mice. Moreover, HMGB1 levels in peritoneal macrophages from BLP-tolerized mice were reduced significantly. Hence, tolerization with BLP leads to a down-regulation of HMGB1 protein synthesis and release. The improved survival associated with BLP tolerance could thus be explained by a reduction in HMGB1, were the latter associated with lethality in BLP-related sepsis. In testing this hypothesis, it was noted that neutralization of HMGB1, using anti-HMGB1 antibodies, abrogated BLP-associated lethality almost completely. To conclude, tolerization with BLP leads to a down-regulation of HMGB1, thus offering a novel means of targeting the latter. HMGB1 is also a mediator of lethality in BLP-related sepsis.

Physicochemical and biological analysis of synthetic bacterial lipopeptides: validity of the concept of endotoxic conformation

The importance of the biological function and activity of lipoproteins from the outer or cytoplasmic membranes of Gram-positive and Gram-negative bacteria is being increasingly recognized. It is well established that they are like the endotoxins (lipopolysaccharide (LPS)), which are the main amphiphilic components of the outer membrane of Gram-negative bacteria, potent stimulants of the human innate immune system, and elicit a variety of proinflammatory immune responses. Investigations of synthetic lipopeptides corresponding to N-terminal partial structures of bacterial lipoproteins defined the chemical prerequisites for their biological activity and in particular the number and length of acyl chains and sequence of the peptide part. Here we present experimental data on the biophysical mechanisms underlying lipopeptide bioactivity. Investigation of selected synthetic diacylated and triacylated lipopeptides revealed that the geometry of these molecules (i.e. the molecular conformations and supramolecular aggregate structures) and the preference for membrane intercalation provide an explanation for the biological activities of the different lipopeptides. This refers in particular to the agonistic or antagonistic activity (i.e. their ability to induce cytokines in mononuclear cells or to block this activity, respectively). Biological activity of lipopeptides was hardly affected by the LPS-neutralizing antibiotic polymyxin B, and the biophysical interaction characteristics were found to be in sharp contrast to that of LPS with polymyxin B. The analytical data show that our concept of "endotoxic conformation," originally developed for LPS, can be applied also to the investigated lipopeptide and suggest that the molecular mechanisms of cell activation by amphiphilic molecules are governed by a general principle.

Correlation between diverse cyclic lipopeptides production and regulation of growth and substrate utilization by Bacillus subtilis strains in a particular habitat

The two Bacillus subtilis strains (DM-03 and DM-04) were isolated from two extremely different habitats; one from the traditional fermented food and another one from a petroleum contaminated soil sample. These strains produced quantitatively and qualitatively different cyclic lipopeptides isoforms under laboratory culture conditions. MALDI-TOF mass spectral analysis revealed that lipopeptide profile varied according to the producing B. subtilis strains; iturins and surfactins isoforms were pre-dominant cyclic lipopeptides produced by B. subtilis DM-03 and DM-04 strains, respectively. A comparative study showed that these strains possessed distinct preferences for the carbon and nitrogen substrates, temperature and pH for optimal growth and biosurfactant production. Our study documented that the cyclic lipopeptide isoforms produced by the respective strains played an important role in the utilization of available hydrophobic substrate(s) from their natural habitats and conferred some kind of competitive advantage to the producing B. subtilis strains in their parent ecological niche.

Toxicological evaluation of micafungin ophthalmic solution in rabbit eyes

There have been no reports of the topical application of micafungin to the eye. The aim of this study was to evaluate the safety of topical instillation of 0.1% micafungin ophthalmic solution in rabbit eyes. In New Zealand white rabbits (n = 6), 50 microL of 0.1% micafungin solution was topically instilled to 1 eye, and 50 microL of sterile saline was applied to the other eye. Both eyedrops were administered hourly from 7 A.M. for 7 days. Measurements were conducted on corneal thickness, intraocular pressure, endothelial cell density, and lactate dehydrogenase (LDH) activity of tear samples. The eyes were examined slit-lamp biomicroscopically and histopathologically. Topical micafungin application for 1 week did not induce any changes in intraocular pressure, endothelial cell density, and tear LDH. Corneal thickness after instillation was slightly, but significantly, smaller in the micafungin group than in the control group (P = 0.0156, paired t test), but this difference disappeared within 24 hours after the final instillation. Biomicroscopy and histopathology revealed no significant toxic influence of micafungin application on the cornea. Topical instillation of micafungin solution had no apparent toxicity to the cornea. These results warrant future studies on the efficacy of micafungin ophthalmic solution against corneal fungal infection.

Pharmacokinetic and maximum tolerated dose study of micafungin in combination with fluconazole versus fluconazole alone for prophylaxis of fungal infections in adult patients undergoing a bone marrow or peripheral stem cell transplant

In this dose escalation study, 74 adult cancer patients undergoing bone marrow or peripheral blood stem cell transplantation received fluconazole (400 mg/day) and either normal saline (control) (12 subjects) or micafungin (12.5 to 200 mg/day) (62 subjects) for up to 4 weeks. The maximum tolerated dose (MTD) of micafungin was not reached, based on the development of Southwest Oncology Group criteria for grade 3 toxicity; drug-related toxicities were rare. Commonly occurring adverse events considered related to micafungin were headache (6.8%), arthralgia (6.8%), hypophosphatemia (4.1%), insomnia (4.1%), maculopapular rash (4.1%), and rash (4.1%). Pharmacokinetic profiles for micafungin on days 1 and 7 were similar. The mean half-life was approximately 13 h, with little variance after repeated or increasing doses. Mean maximum concentrations of the drug in serum and areas under the concentration-time curve from 0 to 24 h were approximately proportional to dose. There was no clinical or kinetic evidence of interaction between micafungin and fluconazole. Five of 12 patients (42%) in the control group and 14 of 62 (23%) in the micafungin-plus-fluconazole groups had a suspected fungal infection during treatment which resulted in empirical treatment with amphotericin B. The combination of micafungin and fluconazole was found to be safe in this high-risk patient population. The MTD of micafungin was not reached even at doses up to 200 mg/day for 4 weeks. The pharmacokinetic profile of micafungin in adult cancer patients with blood or marrow transplants is consistent with the profile in healthy volunteers, and the area under the curve is proportional to dose.

Biological activities of Bacteroides forsythus lipoproteins and their possible pathological roles in periodontal disease

Bacteroides forsythus is a gram-negative, anaerobic, fusiform bacterium and is considered to be an etiological agent in periodontal disease. A lipoprotein fraction prepared from B. forsythus cells by Triton X-114 phase separation (BfLP) activated human gingival fibroblasts and a human monocytic cell line, THP-1, to induce interleukin-6 production and tumor necrosis factor alpha production. BfLP was found to be capable of inducing nuclear factor-kappaB translocation in human gingival fibroblasts and THP-1 cells. By using Chinese hamster ovary K1 cells transfected with Toll-like receptor genes together with a nuclear factor-kappaB-dependent CD25 reporter plasmid, it was found that signaling by BfLP was mediated by Toll-like receptor 2 but not by CD14 or Toll-like receptor 4. BfLP induced apoptotic cell death in human gingival fibroblasts, KB cells (an oral epithelial cell line), HL-60 cells (a human myeloid leukemia cell line), and THP-1 cells but not in MOLT4 cells (a T-cell leukemia cell line). Caspase-8, an initiator caspase in apoptosis, was found to be activated in these cells in response to BfLP stimulation. Thus, this study suggested that BfLP plays some etiological roles in oral infections, especially periodontal disease, by induction of cell activation or apoptosis.

The Mycobacterium tuberculosis 19-kilodalton lipoprotein inhibits gamma interferon-regulated HLA-DR and Fc gamma R1 on human macrophages through Toll-like receptor 2

Mycobacterium tuberculosis survives in macrophages in the face of acquired CD4(+) T-cell immunity, which controls but does not eliminate the organism. Gamma interferon (IFN-gamma) has a central role in host defenses against M. tuberculosis by activating macrophages and regulating major histocompatibility complex class II (MHC-II) antigen (Ag) processing. M. tuberculosis interferes with IFN-gamma receptor (IFN-gamma R) signaling in macrophages, but the molecules responsible for this inhibition are poorly defined. This study determined that the 19-kDa lipoprotein from M. tuberculosis inhibits IFN-gamma-regulated HLA-DR protein and mRNA expression in human macrophages. Inhibition of HLA-DR expression was associated with decreased processing and presentation of soluble protein Ags and M. tuberculosis bacilli to MHC-II-restricted T cells. Inhibition of HLA-DR required prolonged exposure to 19-kDa lipoprotein and was blocked with a monoclonal antibody specific for Toll-like receptor 2 (TLR-2). The 19-kDa lipoprotein also inhibited IFN-gamma-induced expression of Fc gamma RI. Thus, M. tuberculosis, through 19-kDa lipoprotein activation of TLR-2, inhibits IFN-gamma R signaling in human macrophages, resulting in decreased MHC-II Ag processing and recognition by MHC-II-restricted CD4 T cells. These findings provide a mechanism for M. tuberculosis persistence in macrophages.

In vitro gene transfection in human glioma cells using a novel and less cytotoxic artificial lipoprotein delivery system

PURPOSE

To develop and evaluate a novel artificial lipoprotein delivery system for in vitro gene transfection in human glioma cells.

METHOD

Nanoemulsion was formulated with similar lipid compositions present in natural lipoproteins. The oil phase of nanoemulsion was composed of triolein (70%), egg phosphatidylcholine (22.7%), lysophosphatidylcholine (2.3%), cholesterol oleate (3.0%), and cholesterol (2.0%). To replace the surface protein as in natural lipoprotein, poly-L-lysine was modified to add palmitoyl chains at a basic condition and was incorporated onto the nanoemulsion particles through hydrophobic interaction. A model plasmid DNA, pSV-beta-Gal containing a reporter gene for beta-galactosidase was carried by the nanoemulsion/poly-L-lysine particles. The charge variation of soformed complex was examined by agarose gel electrophoresis and zeta potential measurement. In vitro transfection was conducted on human SF-767 glioma cell line using this new system. After standard X-Gal staining, transfected cells were observed under light microscope. The effect of chloroquine on the transfection was examined and, finally, the cytotoxicity of this new system was evaluated in comparison with commercial Lipofectamine gene transfection system.

RESULTS

The plasmid DNA was effectively carried by this artificial lipoprotein delivery system and the reporter gene was expressed in the glioma cells. Transfection efficiency was significantly increased by the treatment of chloroquine, indicating that endocytosis possibly was the major cellular uptake pathway. Compared to Lipofectamine system, this new delivery system demonstrated similar transfection efficiency but a much lower cytotoxicity. In the experiment, the cell viability showed up to 75% using this system compared to only 24% using Lipofectamine system.

CONCLUSION

A new artificial lipoprotein delivery system was developed for in vitro gene transfection in tumor cells. The new system showed similar transfection efficiency but a much lower cytotoxicity compared with commercial Lipofectamine system.

Extracellular ATP regulates cell death of lymphocytes and monocytes induced by membrane-bound lipoproteins of Mycoplasma fermentans and Mycoplasma salivarium

The cytotoxicities of lipoproteins of Mycoplasma fermentans and Mycoplasma salivarium to a lymphocytic cell line, MOLT-4, and a monocytic cell line, HL-60, was upregulated by ATP added extracellularly in a dose-dependent manner. These lipoproteins induced ATP release and plasma membrane permeability increase in these cell lines. In addition, periodate-oxidized ATP, an antagonist for P2X purinergic receptors, suppressed the cytotoxicity of the lipoproteins, suggesting the possibility that P2X receptors for ATP play crucial roles in the cytotoxicity. Activation of caspase-3 induced by the lipoproteins, which was assessed by the cleavage of the synthetic substrate DEVD-pNA and the endogenous substrate poly(ADP-ribose) polymerase, was also upregulated and downregulated by extracellular ATP and periodate-oxidized ATP, respectively. On the basis of these results, this study suggests that mycoplasmal lipoproteins induce the permeability increase in lymphocytes and monocytes, by which ATP is released, and the ATP regulates the cytotoxicities of the lipoproteins to the cells, possibly by interaction with ATP receptors such as P2X purinergic receptors.

Comparative antifungal activities and plasma pharmacokinetics of micafungin (FK463) against disseminated candidiasis and invasive pulmonary aspergillosis in persistently neutropenic rabbits

Micafungin (FK463) is an echinocandin that demonstrates potent in vitro antifungal activities against Candida and Aspergillus species. However, little is known about its comparative antifungal activities in persistently neutropenic hosts. We therefore investigated the plasma micafungin pharmacokinetics and antifungal activities of micafungin against experimental disseminated candidiasis and invasive pulmonary aspergillosis in persistently neutropenic rabbits. The groups with disseminated candidiasis studied consisted of untreated controls (UCs); rabbits treated with desoxycholate amphotericin B (DAMB) at 1 mg/kg of body weight/day; or rabbits treated with micafungin at 0.25, 0.5, 1, and 2 mg/kg/day intravenously. Compared with the UCs, rabbits treated with micafungin or DAMB showed significant dosage-dependent clearance of Candida albicans from the liver, spleen, kidney, brain, eye, lung, and vena cava. These in vivo findings correlated with the results of in vitro time-kill assays that demonstrated that micafungin has concentration-dependent fungicidal activity. The groups with invasive pulmonary aspergillosis studied consisted of UCs; rabbits treated with DAMB; rabbits treated with liposomal amphotericin B (LAMB) at 5 mg/kg/day; and rabbits treated with micafungin at 0.5, 1, and 2 mg/kg/day. In comparison to the significant micafungin dosage-dependent reduction of the residual burden (in log CFU per gram) of C. albicans in tissue, micafungin-treated rabbits with invasive pulmonary aspergillosis had no reduction in the concentration of Aspergillus fumigatus in tissue. DAMB and LAMB significantly reduced the burdens of C. albicans and A. fumigatus in tissues (P < 0.01). Persistent galactomannan antigenemia in micafungin-treated rabbits correlated with the presence of an elevated burden of A. fumigatus in pulmonary tissue. By comparison, DAMB- and LAMB-treated animals had significantly reduced circulating galactomannan antigen levels. Despite a lack of clearance of A. fumigatus from the lungs, there was a significant improvement in the rate of survival (P < 0.001) and a reduction in the level of pulmonary infarction (P < 0.05) in micafungin-treated rabbits. In summary, micafungin demonstrated concentration-dependent and dosage-dependent clearance of C. albicans from persistently neutropenic rabbits with disseminated candidiasis but not of A. fumigatus from persistently neutropenic rabbits with invasive pulmonary aspergillosis.

A two step model aimed at delivering antisense oligonucleotides in targeted cells

To be efficient in vivo antisense oligonucleotides must reach the targeted cells and then cross the cellular membrane. We propose a two step system where the oligonucleotide is first electrostatically bound to a peptide coupled to a ligand of a cellular receptor. A complex is formed which allows the oligonucleotide to be bound to the membrane of the targeted cells. These oligonucleotides are then delivered inside the cells by the subsequent use of a transfection agent. As a reductionist model of peptide coupled to a ligand we have used a lipopeptide and characterized by a filter elution assay the stoichiometry between the peptide and the oligonucleotide in the complexes. Using HeLa cultured cells we have shown that addition of these complexes to the cells triggers the oligonucleotide binding to the cell membrane. The subsequent addition of dendrimers allows these antisense oligonucleotides to inhibit a reporter gene inside the cells.

Bacterial wall products induce downregulation of vascular endothelial growth factor receptors on endothelial cells via a CD14-dependent mechanism: implications for surgical wound healing

INTRODUCTION

Vascular endothelial growth factor (VEGF) is a potent mitogenic cytokine which has been identified as the principal polypeptide growth factor influencing endothelial cell (EC) migration and proliferation. Ordered progression of these two processes is an absolute prerequisite for initiating and maintaining the proliferative phase of wound healing. The response of ECs to circulating VEGF is determined by, and directly proportional to, the functional expression of VEGF receptors (KDR/Flt-1) on the EC surface membrane. Systemic sepsis and wound contamination due to bacterial infection are associated with significant retardation of the proliferative phase of wound repair. The effects of the Gram-negative bacterial wall components lipopolysaccharide (LPS) and bacterial lipoprotein (BLP) on VEGF receptor function and expression are unknown and may represent an important biological mechanism predisposing to delayed wound healing in the presence of localized or systemic sepsis.

MATERIALS AND METHODS

We designed a series of in vitro experiments investigating this phenomenon and its potential implications for infective wound repair. VEGF receptor density on ECs in the presence of LPS and BLP was assessed using flow cytometry. These parameters were assessed in hypoxic conditions as well as in normoxia. The contribution of CD14 was evaluated using recombinant human (rh) CD14. EC proliferation in response to VEGF was quantified in the presence and absence of LPS and BLP.

RESULTS

Flow cytometric analysis revealed that LPS and BLP have profoundly repressive effects on VEGF receptor density in normoxic and, more pertinently, hypoxic conditions. The observed downregulation of constitutive and inducible VEGF receptor expression on ECs was not due to any directly cytotoxic effect of LPS and BLP on ECs, as measured by cell viability and apoptosis assays. We identified a pivotal role for soluble/serum CD14, a highly specific bacterial wall product receptor, in mediating these effects. The decreased VEGF receptor density on ECs accruing from the presence of bacterial wall products resulted in EC hyporesponsiveness to rhVEGF and significant abolition of VEGF-directed EC proliferation.

CONCLUSION

These findings suggest that the well-recognized relationship between bacterial sepsis and attenuated wound healing may be due, in part, to the directly suppressive effects of bacterial wall components on EC VEGF receptor expression and, consequently, EC proliferation.

Escherichia coli Braun lipoprotein induces a lipopolysaccharide-like endotoxic response from primary human endothelial cells

All bacteria contain proteins in which their amino-terminal cysteine residue is modified with N-acyl S-diacylglycerol functions, and peptides and proteins bearing this modification are immunomodulatory. The major outer membrane lipoprotein of Escherichia coli, the Braun lipoprotein (BLP), is the prototypical triacylated cysteinyl-modified protein. We find it is as active as LPS in stimulating human endothelial cells to an inflammatory phenotype, and a BLP-negative mutant of E. coli was less inflammatory than its parental strain. While the lipid modification was essential, the lipidated protein was more potent than a lipid-modified peptide. BLP associates with CD14, but this interaction, unlike that with LPS, was not required to elicit endothelial cell activation. BLP stimulated endothelial cell E-selectin surface expression, IL-6 secretion, and up-regulation of the same battery of cytokine mRNAs induced by LPS. Quantitative microarray analysis of 4400 genes showed the same 30 genes were induced by BLP and LPS, and that there was near complete concordance in the level of gene induction. We conclude that the lipid modification of at least one abundant Gram-negative protein is essential for endotoxic activity, but that the protein component also influences activity. The equivalent potency of BLP and LPS, and their complete concordance in the nature and extent of endothelial cell activation show that E. coli endotoxic activity is not due to just LPS. The major outer membrane protein of E. coli is a fully active endotoxic agonist for endothelial cells.

Toxic lactonic lipopeptide from food poisoning isolates of Bacillus licheniformis

Toxins from three Bacillus licheniformis strains connected to a fatal food poisoning were isolated and their structures elucidated. Toxins were purified from methanol extracts of the B. licheniformis biomass using boar sperm cells as the toxicity indicator. The HPLC purified toxins showed protonated masses m/z 1007, 1021 and 1035 in MALDI-TOF-MS. The toxins isolated from the strains of different origins contained the same three components of which and each had a same amino-acid residues L-Gln, L-Leu, D-Leu, L-Val, L-Asp, D-Leu and L-Ile in that order. Toxins were identified as lichenysin A, a cyclic lactonic heptalipopeptide in which the main 3-hydroxy fatty acids are 13-15 carbons in length. We showed that the toxins from food and food poisoning isolates of B. licheniformis were identical to lichenysin A both in the structure and in the toxic symptoms induced to boar spermatozoa. Confocal laser scanning microscopy showed that the acrosome and the plasma membrane of boar spermatozoa were the targets of lichenysin A toxicity.

Antillatoxin and kalkitoxin, ichthyotoxins from the tropical cyanobacterium Lyngbya majuscula, induce distinct temporal patterns of NMDA receptor-mediated neurotoxicity

Curacin-A, antillatoxin and kalkitoxin, natural products from the marine cyanobacterium Lyngbya majuscula, were tested for neurotoxicity in primary cultures of rat cerebellar granule neurons. Curacin-A was non-toxic, whereas antillatoxin and kalkitoxin produced concentration-dependent cytotoxicity with LC50 values of 20.1+/-6.4 and 3.86+/-1.91 nM, respectively. Antillatoxin neurotoxicity was produced acutely, whereas kalkitoxin caused a delayed neurotoxic response. The cytotoxicity produced by both antillatoxin and kalkitoxin was prevented by the non-competitive NMDA receptor antagonists dextrorphan and MK-801.

Bacterial lipoprotein and lipopolysaccharide act synergistically to induce lethal shock and proinflammatory cytokine production

Septic shock is a major cause of death in the world. Although much is known about the role of LPS in septic shock, little is known about the role of other bacterial components. Lipoprotein (LP) is a major component of bacteria in the family Enterobacteriaceae. LP purified from Escherichia coli was shown to induce TNF-alpha and IL-6 production in peritoneal exudate macrophages obtained from LPS-responsive (C3H/HeOuJ) and LPS-nonresponsive (C3H/HeJ) mice. LP and LPS acted synergistically to induce cytokine production not only in C3H/HeOuJ macrophages but also in C3H/HeJ macrophages. These results suggest that LPS can induce cellular signaling in C3H/HeJ macrophages, and that LPS and LP activate macrophages via different receptors and/or signaling pathways. The role LP plays in septic shock was investigated using the mouse D-galactosamine model. LP induced lethal shock and in vivo production of TNF-alpha and IL-6 in both LPS-responsive and LPS-nonresponsive mice. LPS failed to induce lethal shock or in vivo cytokine production in C3H/HeJ mice. However, LP and LPS acted synergistically in inducing lethal shock and in vivo cytokine production in both LPS-responsive and LPS-nonresponsive mice. Finally, a heat-killed preparation of an E. coli mutant strain that lacked LP was shown to be less efficient than heat-killed wild-type E. coli at inducing lethal shock in C3H/HeJ mice. Collectively, these results suggest that LP and LPS induce cytokine production via different mechanisms and that LP plays an important role in septic shock induced by bacteria in the family Enterobacteriaceae.

Experimental haemorrhagic effect of two-domain non-glycosylated tissue factor pathway inhibitor compared to low molecular weight heparin

The glycosylated multivalent three-domain Kunitz inhibitor TFPI is a natural inhibitor of tissue factor-FVIIa complex in the presence of FXa. TFPI has an experimental antithrombotic capacity indistinguishable from LMWH in a prophylactic dose, regardless of glycosylation and of the third domain. An inherited equilibrium between antithrombosis and haemorrhage exists. The aim of the study was to evaluate whether a two-domain non-glycosylated TFPI (117QTFPI1-161) has a bleeding potential in a rat gastric mucosa model. Groups; placebo, LMWH (tinzaparin) 60 and 250 anti-Xa IU/kg and 117 QTFPI1-161 1.0 and 10.0 mg/kg, given i.v. (bolus injection), randomised double dummy design. All actively treated groups significantly prolonged both the bleeding volume (493-984 microliters) and the bleeding time (10-20 min) compared to placebo (41 microliters, 2 min). It was not possible to distinguish a difference between the lower dose of LMWH and 117QTFPI1-161 in either parameter (p = 0.23-0.71). The two doses of 117QTFPI1-161 caused elevation of plasma-TFPI, 18 and 150 times baseline value. Both LMWH doses (0.6-3.2 anti-Xa IU/ml) and both 117QTFPI1-161 doses (0.2-2.7 anti-Xa IU/ml), caused significant effect in the anti-Xa assay, however 117QTFPI1-161 significantly less. Only the largest dose of 117QTFPI1-161 caused significant prolongation in the APTT assay (34 s). Both doses of LMWH caused significant prolongation (60-300 s). LMWH was the only substance to prolong the dilute-PT assay. Non-glycosylated two-domain 1.0 mg/kg TFPI, yielding supraphysiological plasma concentration, has an experimental haemorrhagic potential indistinguishable from LMWH in a prophylactic dose. The effect mediated by this type of TFPI could primarily be due to an inhibition of FXa.

Renal toxicity of albumin and other lipoproteins

Proteinuria may be an independent risk factor for nephrosclerosis. One potential mechanism has emerged with the finding that lipoproteins, including albumin, modulate the biology of mesangial cells and proximal tubular epithelial cells when internalized. Consequent alterations in renal-cell lipid metabolism may underlie some of these effects.

Outer membrane proteins of Pseudomonas aeruginosa as vaccine candidates

We tested the ability of recombinant outer membrane proteins of Pseudomonas aeruginosa to serve as a protective vaccine against this gram negative pathogen under two main pathophysiological events leading to P. aeruginosa sepsis. i) systemic infection during immunosuppression, and ii) bacterial translocation. A hybrid vaccine was cloned combining protective epitopes of outer membrane protein F (OprF) and outer membrane protein I (OprI). This vaccine proved to be highly protective against an intraperitoneal challenge with P. aeruginosa in immunosuppressed mice. Oral immunization of mice, with recombinant Salmonella dublin expressing OprI induced s-IgA antibodies in the gut mucosa against OprI and provided protection against translocation of P. aeruginosa in an immunosuppressed mouse model. To test whether OprI is safe for use in humans, recombinant OprI was purified and used for immunization of volunteers. Vaccination was well tolerated and no major side effects were observed. The induction of serum antibodies against OprI was found to be dose-dependent and was observed in total in 65% of the volunteers.

Antithrombotic effect of recombinant truncated tissue factor pathway inhibitor (TFPI1-161) in experimental venous thrombosis--a comparison with low molecular weight heparin

The aim was to investigate whether a truncated recombinant Tissue Factor Pathway Inhibitor (TFPI1-161), which lacked the third Kunitz-type domain and the basic c-terminal region, had an antithrombotic effect comparable to LMWH in a randomised double-dummy study. The experimental thrombosis was induced in jugular veins, in a total of 40 rabbits by a combination of destruction of the endothelium and restricted blood flow. Group 1: placebo, gr 2: LMWH 60 anti-FXa IU/kg, gr 3-5: 0.1, 1.0 and 10.0 mg/kg TFPI1-161. TFPI1-161 reduced the thrombus weights in all treated groups, significantly in doses of 1.0 and 10.0 mg/kg compared to placebo. The frequency of thrombosis and occlusive thrombosis were also significantly reduced in those doses. The antithrombotic properties of TFPI1-161 (1.0-10.0 mg/kg) measured as thrombus weight, frequency of thrombosis and frequency of occlusive thrombosis was equivalent to the anti-thrombotic properties of LMWH. In the anti-FXa, APTT and PT-assays TFPI1-161 displayed a dose dependent increase of activity. Recombinant-TFPI1-161 did not influence the anti-FIIa-assay. No haemorrhagic side effects were noted.

The interaction of liposomal amphotericin B and serum lipoproteins within the biological milieu

Previously, we have shown that liposomal amphotericin B (L-AmpB) is less nephrotoxic than and equally as effective as free AmpB as treatment of patients with systemic fungal infections; The mechanism of L-AmpB's enhanced therapeutic index, however, remains unknown. This review discusses AmpB's association with lipoproteins, predominantly high-density lipoproteins (HDL) and the biological relevance of transferring AmpB to HDL. We observed that AmpB was less toxic to pig kidney cells when associated with HDL but still remains toxic when associated with low-density lipoproteins (LDL). AmpB's association with HDL or LDL does not alter its antifungal activity. We further found that these kidney cells express high- and low-affinity LDL receptors but only low-affinity HDL receptors. The reduced renal cytotoxicity of HDL-associated AmpB may be due to its lack of interaction with the renal cells, since they have no HDL receptors. Since AmpB interacts with cholesteryl esters in serum, whose transfer between HDL and LDL is regulated by lipid transfer protein (LTP), we addressed the role of this protein on the distribution of AmpB between HDL and LDL. The addition of LTP altered the lipoprotein distribution of AmpB but not of L-AmpB. Furthermore L-AmpB, but not AmpB (except at 20 micrograms/ml), inhibited the LTP-mediated transfer of cholesterol esters from HDL to LDL. It appears therefore, that the decreased nephrotoxicity associated with L-AmpB administration is related to its predominant distribution to HDL, which is regulated by inhibiting of LTP-mediated cholesterol esters transfer activity.

Relation between the biologic activities and chemical structures of synthetic microbial lipopeptide analogs in mice

Mitogenicity, lethal toxicity, and antitumor activity against Meth A fibrosarcoma of chemically synthesized lipopeptide analogs, S-[2,3-bis(palmitoyloxy)-2R-propyl]-N-[(2,2,2)-tri- chloroethoxycarbonyl: Troc group]-cysteinyl-seryl-seryl-asparaginyl-alanine (compound KAB-2), which contain the amino acid sequence of lipopeptide in Escherichia coli, S-[2,3-bis(palmitoyloxy)- 2R-propyl]-N-(Troc- or amino-group)-cysteinyl-asparaginyl-seryl-glycyl-glycine (compound KAB-14 or -20), which is found in the amino acid sequence of lipopeptide in Streptomyces, and the compounds binding one to six amino acids, were examined. The analogs showed the mitogenic activity toward splenocytes of C3H/He mice. Low concentrations (0.4 and 2.0 micrograms/ml) of compounds KAB-20 and -21, which have five and six amino acids, respectively, increased the incorporation of [3H]thymidine better than a high concentration (50 micrograms/ml), suggesting that KAB compounds carrying amino groups exert better mitogenicity than KAB compounds carrying Troc group. The decrease of amino acid number in lipopeptide analogs appears to result in a lowering of mitogenicity at low concentrations. KAB-14 and KAB-2 did not exhibit the lethality at a high dose of 50 micrograms/mouse in galactosamine-loaded C57BL/6 mice. By twice intravenous injections of 50 micrograms against Meth A fibrosarcoma in BALB/c mice, KAB-2 showed a higher inhibitory effect than KAB-14. Based on these results, we concluded that the difference of amino acid sequence in the synthetic lipopeptides affects the potency of biologic activities.

A54145 a new lipopeptide antibiotic complex: microbiological evaluation

A54145 complex is made up of eight factors; A, A1, B, B1, C, D, E, and F which were active in vitro (MIC 0.25 approximately greater than 32 micrograms/ml) against Gram-positive aerobic organisms. The complex, factor B and B1 were found to be active against two strains of Clostridium perfringens. A calcium dependence study on some of the factors showed that their in vitro antibacterial activity was greatly enhanced by the presence of calcium (50 mg/liter) in the media. Resistance build-up was seen when Staphylococcus sp. and Streptococcus sp. were passed seven times in the presence of sublethal concentrations of A54145 antibiotics. This resistance disappeared immediately when the resistant organisms were passed in the absence of the antibiotics. Factor A was very effective against Staphylococcus aureus and Streptococcus pyogenes infections in mice (sc ED50s of 3.3 approximately 2.4 mg/kg x 2, respectively). Factor B was more active against S. pyogenes in vivo (sc ED50, 0.9 mg/kg x 2). Acute mouse toxicities were determined with these antibiotics. Semisynthetic derivatives were evaluated.

Lipolyzed hypertriglyceridemic serum and triglyceride-rich lipoprotein cause lipid accumulation in and are cytotoxic to cultured human endothelial cells. High density lipoproteins inhibit this cytotoxicity

The cytotoxic effect of hypertriglyceridemic (HTG) serum and triglyceride-rich lipoprotein (TG-rich lipoprotein) lipolyzed in vitro by purified lipoprotein lipase on cultured human umbilical vein endothelial cells (HUVECs) was studied. When confluent cultures of HUVECs (8.4 x 10(4)/cm2) were incubated in the presence of control (non-lipolyzed HTG serum) or lipolyzed HTG serum or TG-rich lipoprotein, the lipolyzed HTG serum or TG-rich lipoprotein was cytotoxic to the HUVECs as indicated by their detachment from the culture dish; the lipolyzed serum at 10% of the culture medium or lipolyzed TG-rich lipoprotein at 75 micrograms cholesterol/ml caused the detachment of all (100%) of the cells from the culture dish after a 24 h incubation. Control (non-lipolyzed) HTG serum or non-lipolyzed TG-rich lipoprotein at the same or higher concentration was not cytotoxic to the cells. The HUVECs incubated for 48 h with low (sublethal) doses of lipolyzed TG-rich lipoprotein (10-50 micrograms cholesterol/ml) contained massive lipid inclusions; no lipid inclusions were seen within the cells when the culture medium contained control non-lipolyzed TG-rich lipoproteins. Finally, when high density lipoprotein (HDL) was added to the culture medium at the same concentration as the cytotoxic lipolyzed TG-rich lipoprotein (75 micrograms cholesterol/ml), the cytotoxic effect of the lipolyzed TG-rich lipoprotein was inhibited. These data suggest that the interaction of endothelial cells with lipolytic remnants of TG-rich lipoprotein may play a role in the pathogenesis of atherosclerosis and that HDL may play an important role in inhibition of the endothelial cell injury produced by the lipolytic remnants of TG-rich lipoprotein.

Cytotoxicity of remnants of triglyceride-rich lipoproteins: an atherogenic insult?

None of more widely accepted theories of atherogenesis can explain all the more pertinent features of atherosclerosis: a) foam dell formation; b) endothelial cell stress/injury; c) protective effect of HDL; d) atherogenicity of triglyceride-rich lipoproteins; e) the vesicular nature of early lipid deposits in atherosclerosis, f) dissociation of diet risk from the risk due to elevation in plasma cholesterol; or g) correlation of postprandial lipemia with CAD risk. The data obtained from our studies provide a new theory of atherogenesis. This theory is that: a) lipolytic surface remnants of TG-rich lipoproteins may represent a major class of atherogenic lipoproteins which are exacerbated during postprandial hyperlipidemia; b) clearance of these surfaces remnants by HDL in vivo may be one important way that HDL prevents atherosclerosis; c) excess surface remnants may be linked to delayed clearance of potentially atherogenic core remnants, directly linked to atherogenicity via surface remnant-mediated cytotoxicity to cells of the artery wall and/or linked to the deposit of unesterified cholesterol-rich vesicles in early atherosclerosis. An appealing aspect of this hypothesis is that it can account for several unexplained features of atherosclerosis, such as anatomic differences in susceptibility to atherosclerosis in the vascular tree, the preference of early atherosclerosis in humans to the region of the coronary artery subjected to low hemodynamic shear stresses, and the vesicular nature of lipid deposits in early atherosclerosis.

[Histologic study of corneal lesions caused by the slime-GLP glycolipoprotein of Pseudomonas aeruginosa]

The Pseudomonas aeruginosa slime-glycolipoprotein (GLP) is considered as one of the principal pathogenetical factors of the bacterium. A single dose of 100 micrograms of the P. aeruginosa slime-GLP was injected in rabbit corneas intrastromally. Light microscopy showed that 4 hours after the injection, polymorphonuclear leucocytes (PMNs) began to infiltrate the anterior stroma. 24 hours after the intrastromal injection, PMNs had infiltrated full corneal thickness followed by multiple absceses formation, loss of epithelial and endothelial cells, disorganisation of normal collagen fibres and hyperplasy of fibroblasts. These morphological observations are very similar to those observed during experimental P. aeruginosa keratitis and show that the P. aeruginosa slime-GLP is at least in part responsible for the characteristic liquefaction necrosis of the keratitis induced by the P. aeruginosa.

The difficulty of cloning Streptococcus pneumoniae mal and ami loci in Escherichia coli: toxicity of malX and amiA gene products

Stability problems are frequently encountered when cloning pneumococcal DNA in Escherichia coli multicopy plasmid vectors such as derivatives of ColE1. In this paper, we report our investigations of these problems using the pneumococcal mal and ami regions. We offer evidence that, in both cases, promoters are not the primary cause of cloning problems. Indeed, successful cloning of mal and ami promoters has been achieved with standard vectors (devoid of transcriptional terminators flanking the insertion site). Moreover, we show that the entire mal fragment can be introduced into an E. coli strain harboring a chromosomal mutation that reduces plasmid copy number. The cause of the cloning problems has been traced to the malX and amiA structural genes. Overexpression of these genes, which probably encode lipoproteins, could have deleterious effects on E. coli hosts, possibly as a result of impairing the protein export machinery.

Macrophage uptake of a lipoprotein-sequestered toxicant: a potential route of immunotoxicity

An experimental system was chosen to investigate the bioactivity of a lipoprotein-sequestered toxicant at the cellular level based on recent studies demonstrating receptor-mediated uptake of lipoproteins by macrophages. Rat peritoneal exudate cell suspensions (PEC) were exposed to DDT and lipoprotein-sequestered DDT, followed by measurement of DDT uptake, metabolism, and cellular toxicity. In vitro uptake assays demonstrated that PEC suspensions treated for 10, 20, and 30 min with 2.5 microM lipoprotein-sequestered DDT had approximately a twofold increase over the amount of DDT associated with PEC treated with 2.5 microM free DDT. PEC were assayed for DDT metabolites to serve as a measure of the cellular internalization of the toxicant after treatment in vitro for 18 hr with either 1.5 microM DDT or lipoprotein-sequestered DDT. Evidence of DDT metabolism was only observed with PEC which had been treated with lipoprotein-sequestered DDT. These cells contained significantly higher amounts of DDT metabolites as compared to cells treated with unsequestered DDT (over an eightfold difference). Assays measuring macrophage phagocytic activity indicated that macrophages treated for 4.5 hr in vitro with 2.5 microM lipoprotein-sequestered DDT showed significant inhibition in their ability to phagocytize yeast particles. These results suggest that serum lipoproteins may facilitate the cellular uptake of lipoprotein-sequestered toxicants leading to altered cellular function (phagocytosis).

Biochemical alterations in the mouse induced by Pseudomonas aeruginosa and its slime glycolipoprotein

Mice, injected with either live cells of Pseudomonas aeruginosa, or its slime glycolipoprotein (GLP), developed similar lethal syndromes. Within 14 h, biochemical changes in the sera, such as increased urea, aspartate aminotransferase, alanine aminotransferase, and creatinine, as well as decreased glucose, albumin, total protein, uric acid, and alkaline phosphatase, indicated liver and renal dysfunction. These marked alterations were in contrast with the minimal histopathological changes that occurred in these organs. Either live cell or GLP challenge also induced haemolysis in vivo. Immunization with GLP protected mice against most biochemical changes when challenged with live cells but did not protect GLP-challenged mice against the biochemical alterations assayed in the sera.

Carbohydrate mediation of the biological activities of the glycolipoprotein of Pseudomonas aeruginosa

The glycolipoprotein (GLP) extracted from the surface slime of Pseudomonas aeruginosa produces effects in mice similar to those of the viable cell. The lethal activity has been located in the lipid moiety; however, degradation of the carbohydrate moiety with sodium metaperiodate reduced the antigenicity and abolished the lethality of the GLP. Similar degradation with a phage-induced polysaccharide depolymerase reduced the antigenicity only slightly but reduced the lethality over 60%. The neutral sugar composition of the isolated polysaccharide moiety was shown to be that of the parental GLP. Of the component neutral sugars, mannose and its derivatives were capable of inhibiting the agglutination of erythrocytes coated with GLP. Inhibition also occurred with a soluble mannose polymer from the cell walls of yeast. Antiserum to GLP and to its isolated polysaccharide moiety agglutinated yeast cells, whereas antiserum to a glycolipid fragment of the GLP lacking mannose did not. The lethality of the GLP was reduced by degradation with alpha-mannosidase or by blocking the mannose residues with concanavalin A, and the glycolipid fragment showed less lethality than the native GLP. We conclude that mannose, in addition to being an immunodominant sugar, is an effector sugar in the expression of GLP lethality.