bluuebunny/crossref_metadata_2025 huggingface dataset:
Replacement therapy with hydrocortisone in catecholamine-dependent septic shock
Authors: Annane Djillali
Published: June 2007

Septic shock is one of the leading causes of death in intensive care units world-wide. Scientists have made great improvements in understanding mechanisms of inflammation, and the sequence of activation of the various pro- and anti-inflammatory markers is now well known. In contrast, physicians have failed to improve survival from septic shock despite the development of specific targets at various points in the cytokine cascade considered to have a key role in host survival in sepsis. Corticosteroids were among the first anti-inflammatory drugs to be tested in large randomized controlled trials. These trials showed that patients with septic shock did not benefit from a short course of large doses of steroids. More recent findings highlighting the role of the integrity of the hypothalamic—pituitary—adrenal axis to respond appropriately to a septic insult, have led to a re-appraisal of the use of steroids in septic shock. Several randomized controlled trials have evaluated the efficacy of a replacement therapy with hydrocortisone in severe sepsis. These trials strongly suggest that this replacement therapy reduces the morbidity of septic shock and may favorably affect survival from septic shock.
Coagulation and inflammation
Authors: van der Poll Tom
Published: June 2007

Severe infection induces both activation of the coagulation system and multiple other inflammatory mediator cascades. This concise review summarizes the current knowledge of mechanisms that are considered to contribute to the procoagulant response to sepsis. Furthermore, evidence is discussed that mediators traditionally involved in the regulation of the hemostatic balance may also influence other inflammatory pathways.
The role of immune activation in endotoxin-induced atherogenesis
Authors: Wiedermann Christian J. , Kiechl Stefan , Schratzberger Peter , Dunzendorfer Stefan , Weiss Günther , Willeit Johann
Published: June 2007

Some infectious agents may contribute to atherosclerosis by maintaining a heightened state of inflammatory response. Although the risk for atherosclerosis was associated with elevated plasma levels of endotoxin, it is difficult to firmly establish what place endotoxin assumes in the etiology of this disease. As the ability for endotoxin to promote disease may depend on its ability to initiate an inflammatory response, it may be controlled by additional regulatory factors. We measured plasma levels of endotoxin and serum levels of neopterin and soluble interleukin-2 receptor in a random population of 402 men and women, 50—79 years old at the 1990 baseline evaluation (Bruneck Study). End point of the prospective survey was incident (early) atherosclerosis in the carotid arteries as assessed with duplex ultrasound. Subjects with high endotoxin levels (90th percentile) in combination with low neopterin or soluble interleukin-2 receptor levels (below median) did not differ from those with low endotoxin in their risk of incident atherosclerosis. The risk associated with high endotoxin, however, was markedly elevated in subjects with high (above median) neopterin or soluble interleukin-2 receptor levels. The study provides epidemiological evidence that the atherogenic potential of endotoxemia is affected by concomitant immune activation.
Dual roles for HMGB1: DNA binding and cytokine
Authors: Czura Christopher J. , Haichao Wang  , Tracey Kevin J.
Published: June 2007

Effective therapies against overwhelming Gram-negative bacteremia, or sepsis, have eluded successful development. The discovery that tumor necrosis factor (TNF), a host-derived inflammatory mediator, was both necessary and sufficient to recapitulate Gram-negative sepsis raised cautious optimism for developing a targeted therapeutic. However, the rapid kinetics of the TNF response to infection defined an extremely narrow window of opportunity during which anti-TNF therapeutics could be successfully administered. HMGB1 was previously studied as a DNA-binding protein involved in DNA replication, repair, and transcription; and as a membrane-associated protein that mediates neurite outgrowth. A decade-long search has culminated in our identification of HMGB1 as a late mediator of endotoxemia. HMGB1 is released by macrophages upon exposure to endotoxin, activates many other proinflammatory mediators, and is lethal to otherwise healthy animals. Elevated levels of HMGB1 are observed in the serum of patients with sepsis, and the highest levels were found in those patients that died. The delayed kinetics of HMGB1 release indicate that it may be useful to target this toxic cytokine in the development of future therapies.
Invited review: Lipopolysaccharide recognition, internalisation, signalling and other cellular effects
Authors: Diks Sander H. , van Deventer Sander J.H. , Peppelenbosch Maikel P.
Published: June 2007

Despite the importance of bacterial lipopolysaccharide (LPS) in infection and inflammation, many aspects of LPS action remain poorly understood. Especially, the mechanisms by which cells recognise and react to endotoxins or endotoxin-containing particles and how cellular responses are translated into systemic effects have long remained obscure. However, the recent identification of Toll-like receptors as essential participants in endotoxin signal transduction has provided the first answers in clarifying cellular LPS responses. In this review, we discuss the consequences of the clarification of the cellular effects of LPS. Furthermore, for LPS to exert its effects, it has to be transported to its target cells and be recognised before signalling may be induced, and we shall review the current state of affairs with regard to these recognition processes. Finally, we shall investigate how current knowledge may explain endotoxin neutralisation and subsequent detoxification, either through LPS internalisation or via LPS immobilisation, or through the actions of LPS-binding molecules.
DNA diversity of the wla gene cluster among serotype HS:19 and non-HS:19 Campylobacter jejuni strains
Authors: Misawa Naoaki , Kawashima Kumiko , Kondo Fusao , Ban Mishu Allos  , Blaser Martin J.
Published: June 2007

Campylobacter jejuni infection is an important trigger of Guillain-Barré syndrome (GBS), and serotype HS:19 strains are over-represented among GBS-associated isolates. Structures in C. jejuni lipooligosaccharide (LOS) resemble human gangliosides, suggesting that molecular mimicry could be important in triggering the neural injury. We assessed the genetic diversity among 36 C. jejuni serotype HS:19 and non-HS:19 strains by analysis of PCR-based restriction fragment length polymorphism (RFLP) patterns of 12 LOS biosynthesis-related genes ( wla cluster). PCR amplification revealed that the size, order, and direction of each wla gene was identical among all strains tested. However, an additional ORF, located between wlaI and wlaK, was detected in 28 of the 36 isolates examined, and nucleotide sequence analysis revealed that the gene was identical to orfE in C. jejuni strain NCTC 11168. An inverted repeat motif was found downstream of the wlaI stop codon and upstream of the orfE stop codon, an organization allowing pairing of repeated sequences that could lead to deletion of the internal segment. Digestion of the PCR products with restriction endonuclease DdeI or AluI and cluster analysis of RFLP banding patterns showed that all HS:19 strains were closely related and distinct from non-HS:19 strains, consistent with earlier analyses, suggesting that HS:19 strains represent a highly clonal population. RFLP analysis of wla genes also may be useful for epidemiological studies.
Human models of innate immunity: local and systemic inflammatory responses
Authors: Fiuza Carmen , Suffredini Anthony F.
Published: June 2007

We review human studies where different body sites ( e.g. systemic — intravenous and local — skin or lung) are exposed to small amounts of bacterial components as a means to study innate immunity in vivo. Intravenous endotoxin administration is widely used to assess systemic inflammatory responses, and these have many similarities to those seen in early sepsis. While blood levels of cytokines, activated inflammatory cells, and stress hormones rise acutely, the alveolar space remains relatively protected from these inflammatory responses. Skin blister windows provide a means to study local neutrophil exudation without systemic inflammatory responses, and has been used to characterize defects in neutrophil transmigration. Recently, skin blister windows have been adapted to study phagocytic cell function in response to bacterial antigens in patients with cirrhosis. Inhalation of endotoxin leads to pulmonary inflammation with increases in broncho-alveolar lavage neutrophils and cytokines and mild systemic responses. Whole lung exposure to endotoxin provides a means to study the pathogenesis of occupational lung disease. These three models are important methods to study innate immune responses and their regulatory mechanisms in normal and diseased states.
The inhibitory action of quercetin on lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophage cells
Authors: Mya Mya Mu  , Chakravortty Dipshikha , Sugiyama Tsuyoshi , Koide Naoki , Takahashi Kazuko , Mori Isamu , Yoshida Tomoaki , Yokochi Takashi
Published: June 2007

The effect of quercetin on lipopolysaccharide (LPS)-induced nitric oxide (NO) production was studied. Quercetin pretreatment significantly inhibited NO production in an LPS-stimulated RAW 264.7 murine macrophage cell line. Post-treatment with quercetin partially inhibited NO production. The inhibitory action of quercetin was due to neither the cytotoxic action nor altered LPS binding. The expression of inducible-type NO synthase (iNOS) was markedly down-regulated by quercetin. Quercetin suppressed the release of free nuclear factor (NF)-κB by preventing degradation of IκB-α and IκB-β. Moreover, quercetin blocked the phosphorylation of extracellular signal regulated kinase 1/2 (Erk1/2), p38, and c-Jun NH2-terminal kinase/stress-activated protein kinase (JNK/SAPK) and, further, the activity of tyrosine kinases in LPS-stimulated RAW cells. Quercetin also inhibited interferon (IFN)-γ-induced NO production. Taken together, these results indicate that the inhibitory action of quercetin on NO production in LPS- and/or IFN-γ-stimulated macrophages might be due to abrogation of iNOS protein induction by impairment of a series of intracellular signal pathways.
Identification of genes involved in biosynthesis of Actinobacillus pleuropneumoniae serotype 1 O-antigen and biological properties of rough mutants
Authors: Labrie Josée , Rioux Stéphane , Wade Mary Margaret , Champlin Franklin R. , Holman Steven C. , Wilson W. William , Savoye Chantal , Kobisch Marylène , Sirois Marc , Galarneau Catherine , Jacques Mario
Published: June 2007

Actinobacillus pleuropneumoniae is an important pathogen of swine. Lipopolysaccharide (LPS) has been identified as the major adhesin of A. pleuropneumoniae and it is involved in adherence to porcine respiratory tract cells. We previously generated seven rough LPS mutants of A. pleuropneumoniae serotype 1 by using a mini-Tn 10 transposon mutagenesis system [Rioux S, Galarneau C, Harel J et al. Isolation and characterization of mini-Tn 10 lipopolysaccharide mutants of Actinobacillus pleuropneumoniae serotype 1. Can J Microbiol 1999; 45: 1017—1026]. The purpose of the present study was to characterize these mutants in order to learn more about LPS O-antigen biosynthesis genes and their organization in A. pleuropneumoniae, and to determine the surface properties and virulence in pigs of these isogenic mutants. By mini-Tn 10 insertions in rough mutants, four putative genes (ORF12, ORF16, ORF17, and ORF18) involved in O-antigen biosynthesis in A. pleuropneumoniae serotype 1 were found within a region of 18 ORFs. This region is homologous to the gene cluster of serotype-specific O-polysaccharide biosynthesis from A. actinomycetemcomitans strain Y4 (serotype b). Two mutants showed homology to a protein with identity to glycosyltransferases (ORF12); two others had the mini-Tn 10 insertion localized in genes encoding for two distinct proteins with identity to rhamnosyltransferases (ORF16 and ORF17) and three showed homology to a protein which is known to initiate polysaccharide synthesis (ORF18). These four ORFs were also present in A. pleuropneumoniae serotypes 9 and 11 that express an O-antigen that serologically cross-reacts with serotype 1. Evaluation of some biological properties of rough mutants seems to indicate that the absence of O-chains does not appear to have an influence on the virulence of the bacteria in pigs and on the overall surface hydrophobicity, charge and hemoglobin-binding activity, or on LAL activation. An acapsular mutant was included in the present study in order to compare the influence of O-chains and capsule polysaccharides on different cell surface properties. Our data suggest that capsular polysaccharides and not O-chains polysaccharides have a major influence on surface properties of A. pleuropneumoniae serotype 1 and its virulence in pigs.
Review: Endotoxin and the hypothalamo-pituitary-adrenal (HPA) axis
Authors: Beishuizen Albertus , Thijs Lambertus G.
Published: June 2007

Endotoxin is considered to be a systemic (immunological) stressor eliciting a prolonged activation of the hypothalamo-pituitary-adrenal (HPA) axis. The HPA-axis response after an endotoxin challenge is mainly due to released cytokines (IL-1, IL-6 and TNF-α) from stimulated peripheral immune cells, which in turn stimulate different levels of the HPA axis. Controversy exists regarding the main locus of action of endotoxin on glucocorticoid secretion, since the effect of endotoxin on this neuro-endocrine axis has been observed in intact animals and after ablation of the hypothalamus; however, a lack of LPS effect has been described at both pituitary and adrenocortical levels. The resulting increase in adrenal glucocorticoids has well-documented inhibitory effects on the inflammatory process and on inflammatory cytokine release. Therefore, immune activation of the adrenal gland by endotoxin is thought to occur by cytokine stimulation of corticosteroid-releasing hormone (CRH) production in the median eminence of the hypothalamus, which, in turn stimulates the secretion of ACTH from the pituitary. Acute administration of endotoxin stimulates ACTH and cortisol secretion and the release of CRH and vasopressin (AVP) in the hypophysial portal blood. During repeated endotoxemia, tolerance of both immune and HPA function develops, with a crucial role for glucocorticoids in the modulation of the HPA axis. A single exposure to a high dose of LPS can induce a long-lasting state of tolerance to a second exposure of LPS, affecting the response of plasma TNF-α and HPA hormones. Although there are gender differences in the HPA response to endotoxin and IL-1, these responses are enhanced by castration and attenuated by androgen and estrogen replacement. Estrogens attenuate the endotoxin-induced stimulation of IL-6, TNF-α and IL-1ra release and subsequent activation in postmenopausal women. There appears to be a temporal and functional relation between the HPA-axis response to endotoxin and nitric oxide formation in the neuro-endocrine hypothalamus, suggesting a stimulatory role for nitric oxide in modulating the HPA response to immune challenges.
Lps2: a new locus required for responses to lipopolysaccharide, revealed by germline mutagenesis and phenotypic screening
Authors: Hoebe Kasper , Xin Du  , Goode Jason , Mann Navjiwan , Beutler Bruce
Published: June 2007

Both forward and reverse genetic techniques have been used to define components of the mammalian lipopolysaccharide (LPS) receptor. TLR4, identified by a forward genetic approach as the product of the classical Lps locus, is the only known transmembrane component of the mammalian LPS receptor. Gene knockout work has also established that LPS signal transduction requires the integrity of CD14, MD-2, and, in part, MyD88, IRAK4, and TRAF-6. However, there is no reason to believe that these are the only proteins that make up the receptor/transducer apparatus. To examine the possibility that other proteins may be involved, we initiated a mutagenesis program, in which germline mutations are induced in mice using N-ethyl-N-nitrosourea (ENU), and macrophages from individual animals are screened for their competence to respond to LPS. We now report the existence of a new locus, Lps2, which is required for TNF production in response to LPS. The Lps2 mutation that we have identified is co-dominant, is similar in phenotypic effect to Lpsd, and does not represent a novel allele of any of the genes that are known to encode the `core' LPS signaling apparatus. The Lps2 mutation does not preclude signaling initiated by peptidoglycan or unmethylated DNA. Hence, genetic data suggest that there is at least one `missing' component of the LPS receptor complex that has yet to be found.
Purinergic receptor regulation of LPS-induced signaling and pathophysiology
Authors: Guerra Alma N. , Fisette Philip L. , Pfeiffer Zachary A. , Quinchia-Rios Beatriz H. , Prabhu Usha , Aga Mini , Denlinger Loren C. , Guadarrama Arturo G. , Abozeid Sara , Sommer Julie A. , Proctor Richard A. , Bertics Paul J.
Published: June 2007

Macrophages express several lipopolysaccharide (LPS) binding proteins and are potently activated by LPS to produce inflammatory mediators. Recent studies have shown that receptors for exogenous nucleotides (P2X and P2Y purinergic receptors) can modulate macrophage production of TNF-α , IL-1β and nitric oxide (NO) following LPS exposure. Macrophages and LPS-stimulated monocytes express elevated levels of P2Y1, P2Y2and P2X7mRNA, suggesting that both P2Y and P2X receptors can contribute to LPS-induced pathophysiology. In addition, oxidized-ATP treatment (which inhibits P2X7) of macrophages blocks LPS-induced NO production, NF-κB and ERK-1/2 activation. Also, an LPS-binding domain located in the P2X7C-terminus appears important for receptor trafficking/function. Moreover, the purinergic receptor ligand 2-MeS-ATP attenuates LPS-induced cytokine and NO production in vivo and ex vivo. These data suggest that P2X7and certain P2Ys are linked to LPS effects, although their relative contribution in vivo is unclear. Accordingly, we tested the capacity of several adenine nucleotides to modulate LPS-induced mortality in mice. We found that the P2X7-directed ligand BzATP was unable to prevent LPS-induced death, whereas 2-MeS-ATP and 2-Cl-ATP, which bind to multiple P2X and P2Y receptors were able to protect mice from LPS-induced death. These data suggest that the co-ordinate action of P2Y and P2X7receptors are critical for controlling LPS responses in vivo and that agents directed against both receptor classes may provide the greatest therapeutic advantage.
Role of interferons in LPS hypersensitivity
Authors: Freudenberg Marina A. , Kalis Christoph , Chvatchko Yolande , Merlin Thomas , Gumenscheimer Marina , Galanos Chris
Published: June 2007

The innate immune response to Gram-negative bacteria depends mainly on the ability of the host to respond to the LPS component. Consequently, the state of LPS sensitivity at the time of infection and the numbers of invading bacteria ( i.e. the amounts of LPS) are primary factors determining the innate responses provoked by Gram-negative pathogens. LPS sensitivity increases following treatment of mice with live or killed micro-organisms. Two types of sensitization have been recognized, strong, IFN-γ-dependent and moderate IFN-γ-independent. IL-12 and IL-18 are intimately involved in the induction of IFN-γ by bacteria. We showed that Gram-negative bacteria induce IFN-γ in mice also by an IFN-β-dependent pathway that requires IL-18 and is independent of IL-12 signaling. This pathway is STAT4 dependent, the activation of which is directly linked to IFN-β. Further, IFN-β can be replaced by IFN-α. While different components of Gram-negative bacteria induce IL-12 and IL-18, LPS seems to be the only component in these bacteria capable of inducing IFN-β. Therefore, the IFN-β pathway of IFN-γ induction, unlike the IL-12 pathway, proceeds only in LPS responder mice. The IFN-α/β-dependent pathway is expected to play a role whenever IFN-α or IFN-β, and IL-18 are produced concomitantly during infection.
The LPS receptor generates inflammatory signals from the cell surface
Authors: Latz Eicke , Visintin Alberto , Lien Egil , Fitzgerald Kate A. , Espevik Terje , Golenbock Douglas T.
Published: June 2007

Bacterial lipopolysaccharides (LPSs) are recognized in mammals by a receptor complex composed of CD14, Toll-like receptor 4 (TLR4), and MD-2. The mechanism of TLR4 function remains to be elucidated. We constructed chimeric TLR molecules C-terminally fused to fluorescent proteins and stably expressed these chimeric constructs in cells. Confocal microscopy revealed TLR4 to be expressed on the plasma membrane and the Golgi apparatus. Time-lapse confocal imaging showed rapid recycling of TLR4/CD14/MD-2 complexes between the Golgi and the plasma membrane. Membrane TLR4 engagement by antibody was sufficient to induce signaling and pharmacological disruption of the Golgi did not affect cellular responses to LPS. Thus, LPS signaling commences after LPS recognition by surface-expressed TLR4 independent of LPS trafficking to the Golgi.
Characteristic biological activities of lipopolysaccharides from Sinorhizobium and Mesorhizobium
Authors: Tsukushi Yasuyo , Kido Nobuo , Saeki Kazuhiko , Sugiyama Tsuyoshi , Koide Naoki , Mori Isamu , Yoshida Tomoaki , Yokochi Takashi
Published: June 2007

The biological actions of lipopolysaccharides (LPSs) from Sinorhizobium meliloti, Mesorhizobium loti and Escherichia coli were compared. In biological activities including lethality, production of tumor necrosis factor (TNF)-α and nitric oxide (NO), adjuvant action and Limulus activity, LPS from S. meliloti exhibited stronger actions than LPS from M. loti, but had a weaker action than LPS from E. coli. On the other hand, M. loti LPS showed a higher activity to activate human complement than S. meliloti LPS. Further, there was a significant difference in polymyxin B binding between S. meliloti LPS and M. loti LPS, suggesting a difference in the lipid A structure. LPSs from S. meliloti and M. loti seem to exhibit characteristic biological actions that may be dependent on the difference in the lipid A structure.
Butyrate enhances the production of nitric oxide in mouse vascular endothelial cells in response to gamma interferon
Authors: Morikawa Akiko , Sugiyama Tsuyoshi , Koide Naoki , Mori Isamu , Mya Mya Mu  , Yoshida Tomoaki , Hassan Ferdaus , Islam Shamima , Yokochi Takashi
Published: June 2007

The effect of butyrate, a natural bacterial product of colonic bacterial flora, on nitric oxide (NO) production in murine vascular endothelial cell line END-D in response to IFN-γ and/or LPS was studied. Butyrate significantly augmented NO production in END-D cells in response to IFN-γ or IFN-γ + LPS, but not LPS alone. The NO production was augmented by the addition of butyrate until 6 h after the stimulation with IFN-γ or IFN-γ + LPS. The augmentation was abolished by the removal of butyrate from the cultures. Butyrate enhanced the expression of inducible type NO synthase (iNOS) in the stimulated END-D cells. Furthermore, butyrate-enhanced NO production in the presence of various signal inhibitors down-regulating the signal pathways using nuclear factor (NF)-κB, mitogen-activated protein (MAP) kinases and Janus tyrosine kinase. The putative mechanism of butyrate-induced augmentation of NO production in response to IFN-γ or IFN-γ + LPS is discussed.
Fever onset is linked to the appearance of lipopolysaccharide in the liver
Authors: Zhonghua Li  , Blatteis Clark M.
Published: June 2007

To assess the relative contributions of different phagocytes to the febrile response of guinea pigs to intravenous (i.v.) and intraperitoneal (i.p.) bacterial endotoxic lipopolysaccharide (LPS), we injected fluorescein isothiocyanate (FITC)-labeled LPS at doses of 37.5, 75, 150, 300 and 900 μg/kg, and measured its distribution and corresponding core temperature (Tc) changes before and at 15, 30, 60, 90, and 120 min after injection. At all times, i.v. FITC-LPS appeared as granular fluorescent patches in circulating leukocytes and hepatic macrophages; its density was proportional to dose. At all doses, the density of i.v. FITC-LPS labeling decreased from its peak 15 min after injection at a rate commensurate with its dose. Intraperitoneal FITC-LPS was also present dose- and time-dependently in peritoneal macrophages, but it appeared later and accumulated more slowly except at the highest dose. Compared with i.v. FITC-LPS, its maximal appearance was always lower in density. No labeling was found at any time in brain and kidney following any dose of i.v. or i.p. FITC-LPS injection. The initiation of Tc rises was best correlated with the presence of FITC-LPS in liver, irrespective of its route of injection. Pretreatment with gadolinium chloride 3 days before LPS injection attenuated the febrile response and reduced FITC-LPS labels in liver. These results suggest that the Kupffer cells may be central to the initiation of the febrile response of guinea pigs to i.v. and i.p. LPS.
A new method for removing endotoxin from plasma using hemocompatible affinity chromatography technology, applicable for extracorporeal treatment of septic patients
Authors: Amoureux Marie-Claude , Hegyi Edit , Le Dzung , Grandics Peter , Tong Hung , Szathmary Susan
Published: June 2007

The pathogenesis of sepsis begins with the proliferation of micro-organisms at a site of infection, followed by invasion of the bloodstream and other organs. Gram-negative bacteria account for a large part of sepsis cases. The structural component of Gram-negative bacteria, endotoxin or lipopolysaccharide (LPS), induces the synthesis and release of endogenous mediators of sepsis. A growing number of investigations of the molecular mechanisms occurring in sepsis, point to endotoxin as a central mediator leading to multi-organ failure and death. In numerous clinical trials, attempts to target molecules downstream of endotoxin have been made, but have not been associated with improved survival. We describe an affinity-based system for the selective removal of endotoxin from plasma. The small-scale device, a 1.5 ml cartridge, contains beads that bind endotoxin with high specificity and efficiency. In addition, evidence is presented that this device does not affect plasma hemostasis, nor does it activate the complement system. Taken together, these results represent a proof of principle for endotoxin removal from plasma, which may be of clinical value to treat sepsis by extracorporeal circulation of the blood through a scaled-up version of this endotoxin-removing device.
TLR-independent pattern recognition receptors and anti-inflammatory mechanisms
Authors: Fraser Iain P. , Stuart Lynda , Ezekowitz R. Alan B.
Published: June 2007

Pattern recognition receptors recognize molecular patterns associated with the surfaces of microbes and apoptotic cells. These receptors act alone and in concert to bind, phagocytose, and transduce cellular signals derived from these molecular patterns. The outcome of these interactions is dependent on the nature of the ligands, and upon the nature and combination of the ligated receptors. Whereas much attention has been focused on the properties and activities of the Toll-like receptors (TLRs) in this process, many other pattern recognition molecules have been described. Here we review some of these non-TLR receptors and their ligands, and focus attention on the mannose binding lectin, a humoral pattern recognition molecule. In addition, we describe how recognition of apopotic cells via pattern recognition receptors appears to result in responses that differ from those elicited by microbial ligands.
Toll and Toll-9 in Drosophila innate immune response
Authors: Bettencourt Raul , Tanji Takahiro , Yagi Yoshimasa , Ip Y. Tony
Published: June 2007

In both insects and mammals, members of the Toll receptor family play important roles in the initial events leading to the activation of immunity genes. The prototypic Toll in Drosophila appears to be activated by a host protein ligand after microbial stimulation. The cellular events and the biological response after Toll activation, however, require further investigation. We used transgenic Drosophila strains expressing NF-κB and Toll proteins to investigate innate immune response in whole larvae and dissected larval fat bodies. Substantial activation of antimicrobial peptide genes was observed after septic injury. To circumvent the contribution of injury-induced response, we used dissected larval fat bodies to show that commercially available microbial compounds were able to alter the cellular distribution of Toll. The results also demonstrate that complex cellular events, including receptor trafficking, likely take place after stimulation of the larval immune tissue. By genome-wide expression analysis, we further show that Toll and Toll-9 may utilize the same signaling pathway in activating many immunity genes. Thus, the innate immune response in Drosophila is regulated by complex mechanisms, which involve Toll and other Toll-related proteins.
Toll-dependent and Toll-independent immune responses in Drosophila
Authors: Imler Jean-Luc , Ferrandon Dominique , Royet Julien , Reichhart Jean-Marc , Hetru Charles , Hoffmann Jules A.
Published: June 2007

The multifaceted response of the fruitfly Drosophila melanogaster to infection by a wide range of microbes is complex and remarkably efficient. Its most prominent aspect is the immune-inducible expression of a set of potent antimicrobial peptides. Genetic analysis of the regulation of the genes encoding these peptides has led to the identification of the receptor Toll as an essential component of the fly's host defense system. In addition, these studies have revealed that the response to Gram-negative bacterial infections involves Toll-independent mechanisms, and that the sensing of infection involves two structurally distinct sets of molecules — the PGRPs and the GNBPs/βGRPs.
Comparison of CpG s-ODNs, chromatin immune complexes, and dsDNA fragment immune complexes in the TLR9-dependent activation of rheumatoid factor B cells
Authors: Marshak-Rothstein Ann , Busconi Liliana , Lau Christina M. , Tabor Abigail S. , Leadbetter Elizabeth A. , Akira Shizuo , Krieg Arthur M. , Lipford Grayson B. , Viglianti Gregory A. , Rifkin Ian R.
Published: June 2007

Synthetic single-stranded oligodeoxynucleotides (15—30 bp) containing CpG motifs and phosphorothioate backbones (CpG s-ODN), immune complexes consisting of anti-nucleosome mAbs and mammalian chromatin (chromatin IC), and immune complexes consisting of anti-hapten mAbs and haptenated-double stranded DNA fragments (~600 bp) can all effectively stimulate transgenic B cells expressing a rheumatoid factor receptor by a TLR9-dependent process. However, differential sensitivity to both s-ODN and small molecule inhibitors suggests that stimulatory CpG sODN and chromatin IC may either access TLR9 via different routes or depend on discrete activation parameters. These data have important implications regarding the therapeutic application of TLR9 inhibitors to the treatment of systemic autoimmune diseases.
Influence of recombinant adenovirus on liver injury in endotoxicosis and its modulation by IL-10 expression
Authors: Oberholzer Caroline , Oberholzer Andreas , Tschoeke Sven K. , Minter Rebecca M. , Bahjat Frances R. , LaFace Drake , Hutchins Beth , Moldawer Lyle L.
Published: June 2007

Adenovirus-based gene therapy offers a unique opportunity to target gene expression to the liver by systemic delivery. However, systemic administration of a first generation adenoviral construct elicits an inflammatory response leading to TNF-α-dependent liver injury. The aim of this study was to evaluate whether the systemic administration of recombinant adenovirus exacerbates a subsequent TNF-α-dependent liver injury induced by D-galactosamine and lipopolysaccharide. Surprisingly, low-dose adenovirus administration (105 particles) protects, while high-dose adenovirus (1010 particles) is associated with an exaggerated hepatic inflammatory response from a subsequent D-galactosamine and lipopolysaccharide challenge. This exacerbation is TNF-α dependent, since treatment with a TNF inhibitor fully protects against the liver injury. Moreover, intravenous administration of an adenoviral construct expressing the anti-inflammatory protein interleukin-10 reduces TNF-α appearance and attenuates the increased hepatocyte injury. Taken together, this report demonstrates potential additive effects of TNF-α responses induced by adenovirus and other inflammatory signals, and suggests that the response can be mitigated by relative adenovirus particle dose or by inhibitors, such as TNF-binding protein or interleukin 10.
Interleukin-18 does not modulate the acute-phase response
Authors: Stuyt Rogier J.L. , Netea Mihai G. , Verschueren Ineke , Dinarello Charles A. , Kullberg Bart Jan , van der Meer Jos W.M.
Published: June 2007

IL-18 is a pro-inflammatory cytokine of the IL-1 family and it induces IL-1, TNF, and IL-6, all of which are endogenous pyrogens. The pyrogenic properties of recombinant IL-18 were studied in a rabbit model of fever. rIL-18 did not cause fever when injected intravenously into rabbits. Furthermore, the ability of rIL-18 to modulate other components of the acute-phase response was assessed. rIL-18 did not induce leukocytosis, or changes of circulating concentrations of lipoproteins and corticosterone in mice. In conclusion, rIL-18 is not able to induce a febrile response in rabbits and does not modulate the acute-phase response in mice.
Apolipoproteins modulate the inflammatory response to lipopolysaccharide
Authors: Berbee Jimmy F.P. , Havekes Louis M. , Rensen Patrick C.N.
Published: June 2007

An increasing body of evidence demonstrates a close interplay between lipoprotein metabolism and sepsis. Sepsis results in an increase of plasma triglycerides within VLDL as a consequence of an enhanced hepatic VLDL production and/or inhibited peripheral and hepatic VLDL clearance. In contrast, sepsis decreases plasma cholesterol within LDL and mainly HDL. The decrease in HDL is accompanied by a loss of mainly apoAI-containing particles, an almost total loss of apoCI, and an increase in apoE-containing HDL, as related to the effect of LPS on a wide range of apolipoproteins, plasma enzymes, lipid transfer factors, and receptors that are involved in HDL metabolism. Reciprocally, all lipoprotein classes have been shown to bind LPS and to attenuate the biological response to LPS in vitro and in rodents. Moreover, triglyceride-rich lipoproteins protect rodents against death from LPS and bacterial sepsis. Accumulating evidence indicates that apolipoproteins such as apoE and apoAI, and not the lipid moieties of the particles, may be responsible for these protective effects of lipoproteins. Therefore, to increase our understanding of the complex interaction between lipoprotein metabolism and sepsis, further studies that address the specific roles of apolipoproteins in sepsis are warranted.
Review: Lipopolysaccharide inner core oligosaccharide structure and outer membrane stability in human pathogens belonging to the Enterobacteriaceae
Authors: Frirdich Emilisa , Whitfield Chris
Published: June 2007

In the Enterobacteriaceae, the outer membrane is primarily comprised of lipopolysaccharides. The lipopolysaccharide molecule is important in mediating interactions between the bacterium and its environment and those regions of the molecule extending further away from the cell surface show a higher amount of structural diversity. The hydrophobic lipid A is highly conserved, due to its important role in the structural integrity of the outer membrane. Attached to the lipid A region is the core oligosaccharide. The inner core oligosaccharide (lipid A proximal) backbone is also well conserved. However, non-stoichiometric substitutions of the basic inner core structure lead to structural variation and microheterogeneity. These include the addition of negatively charged groups (phosphate or galacturonic acid), ethanolamine derivatives, and glycose residues (Kdo, rhamnose, galactose, glucosamine, N-acetylglucosamine, heptose, Ko). The genetics and biosynthesis of these substitutions is beginning to be elucidated. Modification of heptose residues with negatively charged molecules (such as phosphate in Escherichia coli and Salmonella and galacturonic acid in Klebsiella pneumoniae ) has been shown to be involved in maintaining membrane stability. However, the biological role(s) of the remaining substitutions is unknown.
MD-2 and Der p 2 — a tale of two cousins or distant relatives?
Authors: Manček Keber Mateja , Gradišar Helena , Jerala Roman
Published: June 2007

MD-2, an LPS-binding protein is essential for the recognition of LPS by TLR4. MD-2 belongs to the ML superfamily of lipid-binding proteins. The tertiary structure of mite allergen protein Der p 2 was identified as having the protein fold most compatible with the sequence of MD-2. Comparison of MD-2 and Der p 2 reveals that they have many common biochemical characteristics: they are both rich in β-structure and they are both very stable proteins as they both unfold only above 90°C. In Der p 2, six cysteine residues form three disulfide bridges. We determined one free cysteine residue per recombinant biologically active MD-2 molecule, supporting similar disulfide topology with three disulfides bridges as in Der p 2. MD-2 binds LPS with high affinity; however, only weak binding of LPS was detected with Der p 2. Comparison of electrostatic potentials of the structural model of MD-2 and Der p 2 indicates a region of high positive potential on MD-2 and its absence in Der p 2, which may be the reason for its weak binding of LPS. We suggest that Der p 2 and its homologues probably do not have a role in response to Gram-negative bacteria in insects and that MD-2 family members with their specific role in innate immunity probably evolved from an ML ancestor only in higher vertebrates.
RETRACTED: Low-dose endotoxin elicits variability in the inflammatory response in healthy volunteers
Authors: Stephens Robert C.M. , O'Malley Catherine M.N. , Frumento Robert J. , Mythen Michael G. , Bennett-Guerrero Elliott
Published: June 2007

At the request of the Editors and Robert C.M. Stephens, the following article has been retracted. Robert C.M. Stephens, Catherine M.N. OMalley, Robert J. Frumento, Michael G. Mythen, and Elliott Bennett-Guerrero Low-dose endotoxin elicits variability in the inflammatory response in healthy volunteers. Journal of Endotoxin Research August 2005 11: 207–212, doi:10.1177/09680519050110040401 It has been brought to the attention of the Editor and the Publisher that a research misconduct investigation was carried out by Columbia University into allegations made against Mr Robert J. Frumento regarding the data reported in above article. The investigation concluded that Mr Frumento had fabricated data for white cell counts, platelet counts, and CRP. Please note that Journal of Endotoxin Research was the former title of Innate Immunity.
Anti-endotoxin properties of cationic host defence peptides and proteins
Authors: Bowdish Dawn M.E. , Hancock Robert E.W.
Published: June 2007

The innate immune system of mammals contains a series of peptides with overall positive charge and an amphipathic structure which have a variety of important properties in host defences. Although these are often termed cationic antimicrobial peptides, they have numerous roles in innate defences in all complex species of life and thus we prefer to refer to them as host defence peptides. These roles include: (i) an ability to kill micro-organisms directly, ranging from bacteria to viruses, fungi, parasites and helminths; (ii) an adjuvant activity in the adaptive response; and (iii) a multiplicity of roles in modulating innate immunity, including an apparent ability to stimulate protective innate immunity while suppressing harmful inflammatory/septic responses. This latter property may be one of the more important activities of these peptides in vivo. Innate immunity is thought to be triggered by the interaction of conserved bacterial components with particular receptors including Toll-like receptors (TLRs) on host cells. However, the initiation of the innate immune response through this route may trigger a pro-inflammatory cascade that is the principle cause of harmful conditions such as sepsis. Since we are exposed to potentially dangerous pathogens on a daily basis, the host response must contain certain checks and balances. We propose that host defence peptides have a role in feed-back modulation of inflammation under normal (low-pathogen exposure) conditions. This review surveys the available information regarding the antiendotoxic/anti-inflammatory properties of host defence peptides, and will address whether this potential might be exploited for therapeutic benefit in sepsis.
Non-LPS targets and actions of LPS binding protein (LBP)
Authors: Schröder Nicolas W.J. , Schumann Ralf R.
Published: June 2007

LPS binding protein (LBP) was discovered about 20 years ago because of its ability to bind to bacterial lipopolysaccharide (LPS). We have shown that in addition to its complex function of transferring LPS to its cellular receptor into the cell or into lipoproteins, LBP also binds to other bacterial compounds and can modulate their ability to stimulate the host's innate immune system. The majority of compounds found to also interact with LBP are amphiphilic molecules such as glycolipids or lipoproteins. Lipoteichoic acid (LTA) of different Gram-positive bacteria is recognized by LBP and both its complexation with CD14 and biological activity towards immune cells is modulated by LBP. LTA-like glycolipids isolated from spirochetes are recognized by LBP and initiate signaling in the presence of LBP. Lipopeptides corresponding to lipoproteins present in spirochetes, Mycobacterium spp. and Gram-negative bacteria as well as Mycoplasma spp. are also recognized by LBP. Together with the growing number of related proteins of the BPI-PLUNC family, LBP apparently as soluble mediator has the important ability to recognize a variety of bacterial pathogens before cellular contact has been established. The different sources of LBP in tissues such as lung and intestine further support its role as an important defense molecule.
The response of ferritin to LPS and acute phase of Pseudomonas infection
Authors: Ong Derrick Sek Tong , Lihui Wang  , Yong Zhu  , Ho Bow , Jeak Ling Ding
Published: June 2007

Plasma ferritin is an important extracellular iron storage molecule, whose concentration increases drastically in cancer and infection. During infection, the pathogen usurps host iron for its survival and pathogenicity; hence, maintenance of the plasma ferritin level during infection is a crucial host defence mechanism. In this study, the horseshoe crab plasma ferritin complex was purified, characterized, and its involvement in innate immune defence was investigated. The plasma ferritin appears as a 21-kDa subunit on SDS-PAGE. Full-length ferritin-H cDNAs (CrFer-H1 and CrFer-H2) were cloned. Analysis of the 5′ UTR indicates the existence of a functional iron-response element, suggesting that both the CrFer-H genes may be post-transcriptionally regulated. Northern analysis shows that the CrFer-H is ubiquitously expressed. Within 3 h of lipopolysaccharide challenge, the gene is up-regulated by > 12-fold. In contrast, iron-loading did not result in any significant change. When challenged with Pseudomonas aeruginosa , the plasma ferritin disappeared between 6—48 h and re-appeared thereafter, suggesting that during infection, ferritin may be concealed intracellularly as it withholds iron from the invading pathogen. Taken together, these results provide insights into the importance of plasma ferritin as an evolutionarily conserved molecule for the iron-withholding strategy of innate immunity.
New insights into the post-translational modification of Toll-like receptor signaling molecules
Authors: Dunne Aisling , O'Neill Luke
Published: June 2007

Deregulation of Toll-like receptor (TLR) mediated responses can have devastating effects on the host if left unchecked. It is, therefore, critical that control is exerted at several levels. In this review, we discuss post-translational modification of TLRs and their associated signaling molecules as one such means of control. In particular, we focus on the phosphorylation, ubiquitination and de-ubiquitination of various components of TLR signaling pathways.
Liver argininosuccinate synthase binds to bacterial lipopolysaccharides and lipid A and inactivates their biological activities
Authors: Satoh Motonobu , Iwahori Tsuguya , Sugawara Naoki , Yamazaki Masatoshi
Published: June 2007

The liver is known to clear and detoxify circulating lipopolysaccharide (LPS). To characterize the molecules involved in this process in the liver, we attempted to purify mouse liver protein(s) that can interact with lipid A, a biologically active portion of LPS. By partially purifying the inactivating activity against a synthetic lipid A analog, we observed the enrichment of a 45-kDa protein in the active fractions. The internal amino acid sequences of the protein were identical with those of argininosuccinate synthase (EC 6.3.4.5). To examine whether argininosuccinate synthase can interact with lipid A, we purified the enzyme from mouse liver and found the co-elevation of the specific enzyme activity and specific lipid A-inactivating activity, indicating that argininosuccinate synthase is the major lipid A-interacting protein in liver. Argininosuccinate synthase also inhibited the biological activities (macrophage activation and Limulus test) of natural lipid A and rough-type LPS but not smooth-type LPS. The enzyme activity was inhibited by lipid A and rough-type LPS and also by smooth-type LPS. Native gel electrophoresis of a mixture of argininosuccinate synthase and LPS and immunoprecipitation of a mixture of argininosuccinate synthase and [3H]-LPS with anti-argininosuccinate synthase antiserum showed that argininosuccinate synthase stably bound lipid A and LPS. These findings, together, indicate that argininosuccinate synthase can effectively bind LPS in the liver.
Apoptosis induction in gastric mucous cells in vitro: lesser potency of Helicobacter pylori than Escherichia coli lipopolysaccharide, but positive interaction with ibuprofen
Authors: Durkin Emma , Moran Anthony P. , Hanson Peter J.
Published: June 2007

Non-steroidal anti-inflammatory drugs (NSAIDs) cause peptic ulcer disease, but whether they interact with Helicobacter pylori to promote damage is controversial. Moreover, the reported induction of apoptosis in gastric cells by H. pylori lipopolysaccharide (LPS) (10—9 g/ml) contrasts with studies showing low immunological potency of this LPS. Therefore, the effects of LPS from H. pylori NCTC 11637 and Escherichia coli O111:B4 on apoptosis in a primary culture of guinea-pig gastric mucous cells were investigated in the presence and absence of the NSAID, ibuprofen. Cell loss was estimated by a crystal violet assay, and apoptosis determined from caspase activity and from condensation and fragmentation of nuclei. Exposure to E. coli LPS for 24 h caused cell loss and enhanced apoptotic activity at concentrations ≥ 10—9 g/ml, but similar effects were only obtained with H. pylori LPS at concentrations ≥ 10— 6 g/ml. Although ibuprofen (250 µM) caused cell loss and apoptosis, addition of either E. coli or H. pylori LPSs further enhanced these effects. In conclusion, LPS and ibuprofen interact to enhance gastric cell loss and apoptosis. In such interactions, E. coli LPS is more potent than that of H. pylori. The low potency of H. pylori LPS may contribute to a chronic low-grade gastritis that can be enhanced by the use of NSAIDs.