Lipopolysaccharide: neutralization by polymyxin B shuts down the signaling pathway of nuclear factor kappaB in peripheral blood mononuclear cells, even during activation

A key protein from Borrelia burgdorferi could stimulate cytokines in human microglial cells and inhibitory effects of Cucurbitacin IIa

Lyme neuroborreliosis (LNB) is an infectious disease of the nervous system caused by Borrelia burgdorferi (Bb) infection. However, its pathogenesis is not fully understood. We used recombinant BmpA (rBmpA) to stimulate human microglia cell HMC3, then collected the culture supernatant and extracted total RNA from cells, and used the supernatant for cytokine chip, then ELISA and qPCR technology were used to validate the results from cytokine chip. After rBmpA stimulation of microglia, 24 inflammation-related cytokines showed elevated expression. Among them, six cytokines (IL-6, IL-8, CCL2, CCL5, CXCL1, and CXCL10) increased significantly in mRNA transcription, three cytokines (IL-6, IL-8, and CXCL10) concentrations in the cell supernatant increased significantly after the rBmpA stimulation, and CuIIa could inhibit expression of these cytokines. The BmpA can stimulate human microglia to produce large amounts of cytokines, leading to the occurrence of inflammation, which may be closely related to the development of LNB. CuIIa can inhibit BmpA-induced cytokine production in microglia, which may have potential therapeutic effects on LNB.

Interaction of Lipopolysaccharide-Spiked Blood with Anti-Fouling Polymyxin B-Modified Glass

Bacterial endotoxin, also known as lipopolysaccharide (LPS), plays a major role in the initiation of sepsis, a severe inflammatory condition. Removal of the toxin from blood is one accepted method of patient treatment. Polymyxin B (PMB)-modified columns have been employed successfully for this purpose via extra-corporeal blood-flow systems that incorporate a cartridge for toxin removal. Herein we demonstrate that PMB-modified glass beads are able to reduce the presence of LPS competitively with the equivalent fiber column used in a commercial cartridge. Analysis by gas chromatography-mass spectrometry and ELISA of released fatty acids from the toxin indicates that PMB does not physically capture or significantly remove LPS from the blood samples. In reality, interaction between the surface-bound PMB and the toxin may lead to disaggregation or monomerization of LPS aggregates. As aggregates are the bioactive form of LPS, it is possible that the monomerization of these entities may be the mechanism by which their toxicity is reduced. Moreover, this work indicates that LPS monomers are stabilized subsequent to disaggregation induced by PMB.

The Effect of C-Phycocyanin on Microglia Activation Is Mediated by Toll-like Receptor 4

The blue-green alga Spirulina platensis is rich in phycocyanins, that exhibit a wide range of pharmacological actions. C-phycocyanin (C-PC), in particular, possesses hepatoprotective, nephroprotective, antioxidant, and anticancer effects. Furthermore, several studies have reported both anti- and proinflammatory properties of this pigment. However, the precise mechanism(s) of action of C-PC in these processes remain largely unknown. Therefore, here we explored the C-PC effect in in vitro microglia activation. The effect of C-PC on the expression and release of IL-1β and TNF-α and the activation of NF-κB was examined in primary microglia by real-time PCR, ELISA, and immunofluorescence. Treatment with C-PC up-regulated the expression and release of IL-1β and TNF-α. C-PC also promoted the nuclear translocation of the NF-κB transcription factor. Then, to elucidate the molecular mechanisms for the immunoregulatory function of C-PC, we focused on investigating the role of Toll-like receptor 4 (TLR4). Accordingly, several TLR4 inhibitors have been used. Curcumin, ciprofloxacin, L48H37, and CLI-095 that suppresses specifically TLR4 signaling, blocked IL-1β and TNF-α. Overall, these results indicate the immunomodulatory effect of C-PC in microglia cultures and show for the first time that the molecular mechanism implicated in this effect may involve TLR4 activation.

Bacteria-targeting liposomes for enhanced delivery of cinnamaldehyde and infection management

PURPOSE

Drug-resistant gram-negative bacteria have emerged as a global crisis. Therefore, novel antibiotics and novel anti-infection strategies are urgently needed. Current antibiotics remain unsatisfactory due to poor targeting efficiency and poor drug penetration through the bacterial cell wall. Thus, targeted delivery of antibiotics into gram-negative bacteria should be a promising approach. Moreover, gram-negative bacteria can release lipopolysaccharide (LPS) to induce inflammatory response and septic shock, further increasing the disease burden. Hence, it is also promising to neutralize LPS while delivering antibiotics. This study aims to develop a multifunctional bacteria-targeting liposome that could enhance the delivery of antibiotics and adsorb LPS.

METHODS

A polymyxin B (PMB)-modified liposomal system (P-Lipo) was developed as novel carrier of cinnamaldehyde (CA) by using a thin-film evaporation method. Liposome morphology, size, zeta potential, stability, entrapment efficiency, and in vitro release were systematically evaluated. The bacteria-targeting effect and LPS-neutralizing capacity of P-Lipo were evaluated both in vitro and in vivo. The antibacterial effect of CA-loaded P-Lipo was assessed in Escherichia coli (E. coli) O157:H7 and Pseudomonas aeruginosa (P. aeruginosa). Ultimately, the therapeutic effect of P-CA-Lipo was investigated in E. coli O157:H7-infected mice.

RESULTS

P-Lipo was successfully synthesized and encapsulated with CA, which was well characterized. Both in vivo and in vitro experiments demonstrated that P-Lipo could efficiently target the E. coli after modification with PMB. Compared with free CA, CA-Lipo, and P-Lipo, P-CA-Lipo exhibited a significantly enhanced inhibitory effect on E. coli and P. aeruginosa. Further analysis demonstrated that P-CA-Lipo improved the bacterial uptake of CA and enhanced its antibacterial effect. It was also confirmed that P-Lipo could neutralize the LPS to avoid the inflammatory responses and inhibit the release of proinflammatory cytokines in both macrophages and mice. Finally, P-CA-Lipo inhibited E. coli-induced skin damage and death in mice and showed good biocompatibility.

CONCLUSION

The P-Lipo could target E. coli by binding with LPS and enhancing the delivery and internalization of CA. In addition, P-Lipo could adsorb free LPS synergistically, thus promoting the infection management. We believe that this strategy can provide innovative insights into antibacterial agent delivery for the treatment of persistent and severe bacterial infections.

Inhibition of lipopolysaccharide-induced suppression of luteal function in isolated perfused bovine ovaries

Recently, we observed that lipopolysaccharide (LPS) suppresses corpus luteum (CL) function in isolated perfused ovaries. It remained unclear if this suppression was due to increased luteal PGF_2α secretion or LPS-induced apoptosis. Therefore, possible impacts of PGF_2α and LPS were inhibited by a non-steroidal anti-inflammatory drug (flunixin) and an endotoxin-binding agent (polymyxin B), respectively. Bovine ovaries with a mid-cycle CL were collected immediately after slaughter and perfused for 240 min. After 50 min of equilibration, either flunixin or polymyxin B (5 μg/ml of each) were added to the perfusion medium of six ovaries, respectively. All ovaries (n = 12) were treated with E.coli LPS (0.5 μg/ml) 60 min after the onset of perfusion, and received 500 I.U. of hCG after 210 min of perfusion. Progesterone and PGF_2α were measured in the effluent perfusate every 10 and 30 min, respectively. Biopsies of the CL were collected every 60 min to determine the mRNA expression of the cytokine TNFA and factors of apoptosis (CASP3, -8). Flunixin-treatment inhibited the increase of PGF_2α after LPS-challenge that was observed in the polymyxin B-treated (PX-LPS) ovaries. After hCG-stimulation, progesterone secretion increased (P< 0.05) in group PX-LPS but not in the flunixin-treated (F-LPS) ovaries. Compared to initial values before LPS-challenge, luteal mRNA expression of TNFA and CASP3 was increased (P< 0.05) in group F-LPS at 120 and 180 min, respectively, and those of CASP8 was decreased (P< 0.05) in PX-LPS at 60 and 120 min after LPS-treatment. In conclusion, although flunixin managed to inhibit PGF_2α, it did not suffice to successfully prevent LPS-induced apoptosis. However, endotoxin-binding polymyxin B resulted in luteal responsiveness to hCG after LPS-challenge.

The multifaceted nature of antimicrobial peptides: current synthetic chemistry approaches and future directions

Bacterial infections caused by 'superbugs' are increasing globally, and conventional antibiotics are becoming less effective against these bacteria, such that we risk entering a post-antibiotic era. In recent years, antimicrobial peptides (AMPs) have gained significant attention for their clinical potential as a new class of antibiotics to combat antimicrobial resistance. In this review, we discuss several facets of AMPs including their diversity, physicochemical properties, mechanisms of action, and effects of environmental factors on these features. This review outlines various chemical synthetic strategies that have been applied to develop novel AMPs, including chemical modifications of existing peptides, semi-synthesis, and computer-aided design. We will also highlight novel AMP structures, including hybrids, antimicrobial dendrimers and polypeptides, peptidomimetics, and AMP-drug conjugates and consider recent developments in their chemical synthesis.

Regulation of Bone Cell Differentiation and Activation by Microbe-Associated Molecular Patterns

Gut microbiota has emerged as an important regulator of bone homeostasis. In particular, the modulation of innate immunity and bone homeostasis is mediated through the interaction between microbe-associated molecular patterns (MAMPs) and the host pattern recognition receptors including Toll-like receptors and nucleotide-binding oligomerization domains. Pathogenic bacteria such as Porphyromonas gingivalis and Staphylococcus aureus tend to induce bone destruction and cause various inflammatory bone diseases including periodontal diseases, osteomyelitis, and septic arthritis. On the other hand, probiotic bacteria such as Lactobacillus and Bifidobacterium species can prevent bone loss. In addition, bacterial metabolites and various secretory molecules such as short chain fatty acids and cyclic nucleotides can also affect bone homeostasis. This review focuses on the regulation of osteoclast and osteoblast by MAMPs including cell wall components and secretory microbial molecules under in vitro and in vivo conditions. MAMPs could be used as potential molecular targets for treating bone-related diseases such as osteoporosis and periodontal diseases.

Removal of Circulating Neutrophil Extracellular Trap Components With an Immobilized Polymyxin B Filter: A Preliminary Study

Components of neutrophil extracellular traps (NETs) are released into the circulation by neutrophils and contribute to microcirculatory disturbance in sepsis. Removing NET components (DNA, histones, and proteases) from the circulation could be a new strategy for counteracting NET-dependent tissue damage. We evaluated the effect of hemoperfusion with a polymyxin B (PMX) cartridge, which was originally developed for treating gram-negative infection, on circulating NET components in patients with septic shock, as well as the effect on phorbol myristate acetate (PMA)-stimulated neutrophils obtained from healthy volunteers. Ex vivo closed loop hemoperfusion was performed through PMX filters in a laboratory circuit. Whole blood from healthy volunteers (incubated with or without PMA) or from septic shock patients was perfused through the circuit. For in vivo experiment blood samples were collected before and immediately after hemoperfusion with PMX to measure the plasma levels of cell-free NETs. The level of cell-free NETs was assessed by measuring myeloperoxidase-associated DNA (MPO-DNA), neutrophil elastase-associated DNA (NE-DNA), and cell-free DNA (cf-DNA). Plasma levels of MPO-DNA, NE-DNA, and cf-DNA were significantly increased after 2 h of PMA stimulation. When the circuit was perfused with blood from septic shock patients or PMA-stimulated neutrophils from healthy volunteers, circulating levels of MPO-DNA, NE-DNA, and cf-DNA were significantly reduced after 1 and 2 h of perfusion with a PMX filter compared with perfusion without a PMX filter. In 10 patients with sepsis, direct hemoperfusion through filters with immobilized PMX significantly reduced plasma levels of MPO-DNA and NE-DNA. These ex vivo and in vivo findings demonstrated that hemoperfusion with PMX removes circulating NET components. Selective removal of circulating NET components from the blood could be effective for prevention/treatment of NET-related inappropriate inflammation and thrombogenesis in patients with sepsis.

Bacterial membrane vesicles from Acinetobacter baumannii induced by ceftazidime are more virulent than those induced by imipenem

Patients with Acinetobacter baumannii bacteremia treated with antipseudomonal cephalosporins showed higher 14-day mortality than patients treated with antipseudomonal carbapenems. We hypothesized that the bacterial membrane vesicles (BMVs) induced by antipseudomonal cephalosporins are more virulent than BMVs induced by antipseudomonal carbapenems.

To simulate the clinical condition with inadequate antimicrobial treatment, carbapenem-resistant A. baumannii was treated with ceftazidime (an antipseudomonal cephalosporin) or imipenem (an antipseudomonal carbapenem) at 1/2 the minimum inhibitory concentration. BMVs and BMV-carried lipopolysaccharide were measured by nanoparticle tracking analysis and western blotting, respectively. Cytokine expression in RAW264.7 macrophages or mice serum induced by the BMVs was determined by ELISA, fluorescent bead-based immunoassay or western blotting. The virulence of the BMVs was assessed in mice. Liquid chromatography tandem-mass spectrometry was used to determine the protein contents of the BMVs.

We found that ceftazidime induced a higher number of BMVs (CAZ-BMV), which carried more LPS, and induced higher expression levels of iNOS, IL-1β, and IL-6 in macrophages, higher expression of many cytokines in mice, more neutrophil infiltration in lung interstitium, and higher mortality in mice than imipenem-induced BMVs (IMP-BMV). When adjusted to same amount of LPS, CAZ-BMV still led to higher mortality than IMP-BMV. Proteomic analysis revealed different protein contents in CAZ-BMV and IMP-BMV. In conclusion, A. baumannii BMVs induced by ceftazidime are more virulent than BMVs induced by imipenem.

The Vacuolating Autotransporter Toxin (Vat) of Escherichia coli Causes Cell Cytoskeleton Changes and Produces Non-lysosomal Vacuole Formation in Bladder Epithelial Cells

Urinary tract infections (UTIs) affect more than 150 million people, with a cost of over 3.5 billion dollars, each year. Escherichia coli is associated with 70–80% of UTIs. Uropathogenic E. coli (UPEC) has virulence factors including adhesins, siderophores, and toxins that damage host cells. Vacuolating autotransporter toxin (Vat) is a member of serine protease autotransporter proteins of Enterobacteriaceae (SPATEs) present in some uropathogenic E. coli (UPEC) strains. Vat has been identified in 20–36% of UPEC and is present in almost 68% of urosepsis isolates. However, the mechanism of action of Vat on host cells is not well-known. Thus, in this study the effect of Vat in a urothelium model of bladder cells was investigated. Several toxin concentrations were tested for different time periods, resulting in 15–47% of cellular damage as measured by the LDH assay. Vat induced vacuole formation on the urothelium model in a time-dependent manner. Vat treatment showed loss of the intercellular contacts on the bladder cell monolayer, observed by Scanning Electron Microscopy. This was also shown using antibodies against ZO-1 and occludin by immunofluorescence. Additionally, changes in permeability of the epithelial monolayer was demonstrated with a fluorescence-based permeability assay. Cellular damage was also evaluated by the identification of cytoskeletal changes produced by Vat. Thus, after Vat treatment, cells presented F-actin distribution changes and loss of stress fibers in comparison with control cells. Vat also modified tubulin, but it was not found to affect Arp3 distribution. In order to find the nature of the vacuoles generated by Vat, the Lysotracker deep red fluorescent dye for the detection of acidic organelles was used. Cells treated with Vat showed generation of some vacuoles without acidic content. An ex vivo experiment with mouse bladder exposed to Vat demonstrated loss of integrity of the urothelium. In conclusion, Vat induced cellular damage, vacuole formation, and urothelial barrier dysregulation of bladder epithelial cells. Further studies are needed to elucidate the role of these vacuoles induced by Vat and their relationship with the pathogenesis of urinary tract infection.

Assessment of polymyxin B-doxycycline in combination against Pseudomonas aeruginosa in vitro and in a mouse model of acute pneumonia

The increasing prevalence of antibiotic resistance in Pseudomonas aeruginosa has created an urgent need for suitable therapy. This study explored the pairing of doxycycline with other antipseudomonal antibiotics, and found that polymyxin B in combination with doxycycline had a synergistic effect against clinical strains of P. aeruginosa. This synergistic combination was studied by checkerboard assays and time-kill curve analysis. Further, in-vitro biofilm disruption, pyoverdine inhibition assays were performed. The efficacy of polymyxin B-doxycycline in combination, administered by inhalation, was evaluated using a mouse model of acute pneumonia. The combination was found to have a synergistic effect in both in-vitro and in-vivo studies. The combination decreased biofilms of P. aeruginosa and reduced the level of pyoverdine, an important siderophore of P. aeruginosa. In addition, the combination decreased the P. aeruginosa population by 3 log₁₀ (P<0.01) in the mouse model of acute pneumonia, and showed an improvement in lung function by inhalation. To the best of the authors' knowledge, this is the first in-vivo study to evaluate the efficacy of polymyxin B in combination with doxycycline against P. aeruginosa, showing a possible promising option for acute pneumonia due to multi-drug-resistant P. aeruginosa.

Decursin negatively regulates LPS-induced upregulation of the TLR4 and JNK signaling stimulated by the expression of PRP4 in vitro

The current investigation was carried out to analyze the correlation of bacterial lipopolysaccharide (LPS) and pre-mRNA processing factor 4B (PRP4) in inducing inflammatory response and cell actin cytoskeleton rearrangement in macrophages (Raw 264.7) and colorectal (HCT116) as well as skin cancer (B16-F10) cells. Cell lines were stimulated with LPS, and the expression of PRP4 as well as pro-inflammatory cytokines and proteins like IL-6, IL-1β, TLR4, and NF-κB were assayed. The results demonstrated that LPS markedly increased the expression of PRP4, IL-6, IL-1β, TLR4, and NF-κB in the cells. LPS and PRP4 concomitantly altered the morphology of cells from an aggregated, flattened shape to a round shape. Decursin, a pyranocoumarin from Angelica gigas, inhibited the LPS and PRP4-induced inflammatory response, and reversed the induction of morphological changes. Finally, we established a possible link of LPS with TLR4 and JNK signaling, through which it activated PRP4. Our study provides molecular insights for LPS and PRP4-related pathogenesis and a basis for developing new strategies against metastasis in colorectal cancer and skin melanoma. Our study emphasizes that decursin may be an effective treatment strategy for various cancers in which LPS and PRP4 perform a critical role in inducing inflammatory response and morphological changes leading to cell survival and protection against anti-cancer drugs.

Fluorescence Imaging of Bacterial Killing by Antimicrobial Peptide Dendrimer G3KL

We recently discovered that peptide dendrimers such as G3KL ((KL)₈(KKL)₄(KKL)₂KKL, K = branching l-lysine) exert strong activity against Gram-negative bacteria including Pseudomonas aeruginosa, Acinetobacter baumannii, and Escherichia coli. Herein, we report a detailed mechanistic study using fluorescence labeled analogs bearing fluorescein (G3KL-Fluo) or dansyl (G3KL-Dansyl), which show a similar bioactivity profile as G3KL. Imaging bacterial killing by super-resolution stimulated emission depletion (STED) microscopy, time-lapse imaging, and transmission electron microscopy (TEM) reveals that the dendrimer localizes at the bacterial membrane, induces membrane depolarization and permeabilization, and destroys the outer leaflet and the inner membrane. G3KL accumulates in bacteria against which it is active; however, it only weakly penetrates into eukaryotic cells without inducing significant toxicity. G3KL furthermore binds to lipopolysaccharide (LPS) and inhibits the LPS induced release of TNF-α by macrophages, similarly to polymyxin B. Taken together, these experiments show that G3KL behaves as a potent membrane disruptive antimicrobial peptide.

Anti-endotoxin Properties of Polymyxin B-immobilized Fibers

Polymyxin B is an antibiotic that shows strong bactericidal activity against Gram-negative bacteria, by binding to and inactivating endotoxin. Systemic administration of polymyxin B in humans is restricted because of its nephrotoxicity and neurotoxicity, and this compound was therefore considered a strong candidate ligand for the extracorporeal selective adsorption of circulating endotoxin in the blood. Toraymyxin® is a direct hemoperfusion column that uses polymyxin B attached to an insoluble carrier to bind endotoxin in the blood. In 1994, the Japanese National Health Insurance system approved the use of Toraymyxin for the treatment of endotoxemia and septic shock.In this chapter, we will review the development, clinical use, and efficacy of Toraymyxin, examine the structure of the Toraymyxin column, and comment on the current position of Toraymyxin in the treatment of severe sepsis and septic shock. We will also highlight some potential new applications of Toraymyxin for pulmonary diseases.

The effect of polymyxin B hemoperfusion on modulation of human leukocyte antigen DR in severe sepsis patients

BACKGROUND

Recent randomized trials have not found that polymyxin B hemoperfusion (PMX-HP) improves outcomes for patients with sepsis. However, it remains unclear whether the therapy could provide benefit for highly selected patients. Monocyte human leukocyte antigen (mHLA-DR) expression, a critical step in the immune response, is decreased during sepsis and leads to worsening sepsis outcomes. One recent study found that PMX-HP increased mHLA-DR expression while another found that the treatment removed HLA-DR-positive cells.

METHODS

We conducted a randomized controlled trial in patients with blood endotoxin activity assay (EAA) level ≥ 0.6. Patients in the PMX-HP group received a 2-h PMX-HP treatment plus standard treatment for 2 consecutive days. Patients in the non-PMX-HP group received only standard treatment. The primary outcome compared the groups on median change in mHLA-DR expression between day 3 and baseline. Secondary outcomes compared the groups on the mean or median change in CD11b expression, neutrophil chemotaxis, presepsin, cardiovascular Sequential Organ Failure Assessment (CVS SOFA) score, vasopressor dose, and EAA level between day 3 and baseline. We further compared the groups on mortality, ICU-free days, ventilator-free days, dialysis dependence status, renal recovery, serum creatinine, vasopressor-free days, and major adverse kidney events (MAKE 28), measured on day 28.

RESULTS

Fifty-nine patients were randomized to PMX-HP (n = 29) and non-PMX-HP (n = 30) groups. At baseline, mHLA-DR expression, CD11b, neutrophil chemotaxis, and clinical parameters were comparable between groups. The median change in mHLA-DR expression between day 3 and baseline was higher in PMX-HP patients than in patients receiving standard therapy alone (P = 0.027). The mean change in CD11b between day 3 and baseline was significantly lower in the PMX-HP group than in the non-PMX-HP group (P = 0.002). There were no significant changes from baseline in neutrophil chemotaxis, presepsin, CVS SOFA scores, vasopressor doses, or EAA level between groups. On day 28 after enrollment, mortality, ICU-free days, ventilator-free days, dialysis dependence status, renal recovery, serum creatinine, vasopressor-free days, and MAKE 28 were comparable between groups.

CONCLUSION

PMX-HP improved mHLA-DR expression in severe sepsis patients. Future studies should examine the potential benefit of PMX-HP in patients with low mHLA-DR expression.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02413541 . Registered on 3 March 2015.

Mechanisms of sepsis-induced immunosuppression and immunological modification therapies for sepsis

Surgical injury can be a life-threatening complication, not only due to the injury itself, but also due to immune responses to the injury and subsequent development of infections, which readily result in sepsis. Sepsis remains the leading cause of death in most intensive care units. Unfavorable outcomes of several high-profile trials in the treatment of sepsis have led researchers to state that sepsis studies need a new direction. The immune response that occurs during sepsis is characterized by a cytokine-mediated hyper-inflammatory phase, which most patients survive, and a subsequent immunosuppressive phase. Therefore, therapies that improve host immunity might increase the survival of patients with sepsis. Many mechanisms are responsible for sepsis-induced immunosuppression, including apoptosis of immune cells, increased regulatory T cells and expression of programmed cell death 1 on CD4+ T cells, and cellular exhaustion. Immunomodulatory molecules that were recently identified include interleukin-7, interleukin-15, and anti-programmed cell death 1. Recent studies suggest that immunoadjuvant therapy is the next major advance in sepsis treatment.

Borrelia burgdorferi basic membrane protein A could induce chemokine production in murine microglia cell line BV2

Lyme neuroborreliosis is a nervous system infectious disease caused by Borrelia burgdorferi (B. burgdorferi). It has been demonstrated that cytokines induced by B. burgdorferi are related to Lyme neuroborreliosis. Microglia is known as a key player in the immune responses that occur within the central nervous system. In response to inflammation, it will be activated and generate cytokines and chemokines. Experiments in vitro cells have showed that B. Burgdorferi membrane protein A (BmpA), a major immunogen of B. Burgdorferi, could induce Lyme arthritis and stimulate human and murine lymphocytes to produce inflammatory cytokines. In our study, the murine microglia BV2 cell line was used as a cell model to explore the stimulating effects of recombinant BmpA (rBmpA); Chemokine chip, ELISA and QPCR technology were used to measure the production of chemokines from microglial cells stimulated by rBmpA. Compared with the negative control group, CXCL2, CCL22, and CCL5 concentrations in the cell supernatant increased significantly after the rBmpA stimulation; the concentration of these chemokines increased with rBmpA concentration increasing; the mRNA expression levels of chemokines (CXCL2, CCL22, and CCL5) in murine BV2 cells increased significantly with 10 μg/mL and 20 μg/mL rBmpA stimulation; CXCL13 was not change after the rBmpA stimulation. Our study shows that chemokines, such as CXCL2, CCL22, and CCL5 were up-regulated by the rBmpA in the BV2 cells. The production of chemokines in Lyme neuroborreliosis may be mainly from microglia cells and the rBmpA may be closely related with the development of Lyme neuroborreliosis.

Hemoperfusion with polymyxin B-immobilized fibers reduced the number of CD16+CD14 + monocytes in patients with septic shock

Background: CD16 +CD14+ monocytes dramatically increase in number in patients with severe infection. Hemoperfusion with PMX-F (direct hemoperfusion with polymyxin B immobilized fibers) has been reported to be a safe and effective treatment for patients with septic shock, although the molecular mechanism that accounts for its effectiveness is still unclear. The purpose of this study was to quantify the number of CD16+CD14+ monocytes in patients with an intra-abdominal infection and to evaluate the effects of PMX-F treatment on clinical parameters and leukocyte surface antigen expression in these patients.

Materials and Methods : Seventeen septic patients who had an intra-abdominal infection were enrolled in this study; 7 of these patients received PMX-F treatment. Peripheral blood samples were obtained immediately after admission, and were also collected from the above 7 patients before, during, and immediately after their PMX-F treatment. The expression of CD14, CD16, and Toll-like receptor (TLR)-4 on these patients' monocytes was evaluated using flow cytometry. In addition, lipopolysaccharide (LPS)-induced production of TNF-α and IL-1β by these cells was measured by ELISA.

Results: Monocytic expression of CD16 and TLR-4 was significantly greater in septic patients than in healthy controls, and their proportion of CD16+CD14 + monocytes was similarly elevated. LPSinduced production of TNF-α and IL-1β by peripheral blood mononuclear cells (PBMCs) of septic patients was significantly reduced compared to controls. Furthermore, there was a reduction in the proportion of CD 16+CD 14+ monocytes during PMX-F treatment, and in the expression of TLR-4 on monocytes after PMX-F treatment.

Conclusions: These results showed that the number of peripheral blood CD16+CD14 + monocytes and monocytic TLR-4 expression were markedly increased, and the production of pro-inflammatory cytokines in response to LPS significantly reduced in patients with sepsis. PMX-F treatment was found to be effective in reducing the number of CD 16+CD 14+ monocytes and in decreasing the monocytic expression of TLR-4 in patients with septic shock.

The importance of early detection of endotoxemia

Endotoxin is considered a key signaling molecule in the pathogenesis of sepsis and septic shock. Anti-endotoxin therapies may result in the improvement of a patient's clinical condition and lower mortality. The pressing clinical challenge is to identify patients for whom endotoxin elimination would be the most beneficial. An endotoxin activity assay (EAA) has been available for detection of endotoxins, allowing selection of patients at high risk of endotoxemia in intensive care units (ICUs). We studied a cohort of 172 consecutive patients who had septic shock on admission to the ICU. Endotoxin activity (EA) was measured with a rapid chemiluminescent EAA, regarded as point-of-care testing. Endotoxemia with a mean EA of 0.59 ± 0.14 EAU was present in 104 patients (60%) and absent in 68 patients (EA = 0.25 ± 0.11 EAU). The risk of endotoxemia increased with the presence of a Gram-negative infection [odds ratio (OR) 3.1, 95% confidence interval (CI) 1.6-5.9; P = 0.001] and bacteremia (OR 3.8, 95% CI 1.6-8.9; P = 0.02) but did not change with a diagnosis of peritonitis (OR 1.03, 95% CI 0.54-1.97; P = 0.90). These findings indicate that anti-endotoxin interventions should be tailored to individual patients based on both clinical conditions and measured endotoxin levels.

Usefulness of ELISA Methods for Assessing LPS Interactions with Proteins and Peptides

Lipopolysaccharide (LPS), the major constituent of the outer membrane of Gram-negative bacteria, can trigger severe inflammatory responses during bacterial infections, possibly leading to septic shock. One approach to combatting endotoxic shock is to neutralize the most conserved part and major mediator of LPS activity (lipid A) with LPS-binding proteins or peptides. Although several available assays evaluate the biological activity of these molecules on LPS (e.g. inhibition of LPS-induced TNF-α production in macrophages), the development of simple and cost-effective methods that would enable preliminary screening of large numbers of potential candidate molecules is of great interest. Moreover, it would be also desirable that such methods could provide information about the possible biological relevance of the interactions between proteins and LPS, which may enhance or neutralize LPS-induced inflammatory responses. In this study, we designed and evaluated different types of ELISA that could be used to study possible interactions between LPS and any protein or peptide. We also analysed the usefulness and limitations of the different ELISAs. Specifically, we tested the capacity of several proteins and peptides to bind FITC-labeled LPSs from Escherichia coli serotypes O111:B4 and O55:B5 in an indirect ELISA and in two competitive ELISAs including casein hydrolysate (hCAS) and biotinylated polymyxin B (captured by deglycosylated avidin; PMX) as LPS-binding agents in the solid phase. We also examined the influence of pH, detergents and different blocking agents on LPS binding. Our results showed that the competitive hCAS-ELISA performed under mildly acidic conditions can be used as a general method for studying LPS interactions, while the more restrictive PMX-ELISA may help to identify proteins/peptides that are likely to have neutralizing properties in vitro or in vivo.

Low-dose polymyxin: an option for therapy of Gram-negative sepsis

Endotoxins are the major components of the outer membrane of most Gram-negative bacteria and are one of the main targets in inflammatory diseases. The presence of endotoxins in blood can provoke septic shock in case of pronounced immune response. Here we show in vitro inactivation of endotoxins by polymyxin B (PMB). The inflammatory activity of the LPS–PMB complex in blood was examined in vitro in freshly drawn blood samples. Plasma protein binding of PMB was determined by ultracentrifugation using membranes with different molecular cut-offs, and PMB clearance during dialysis was calculated after in vitro experiments using the AV1000S filter. The formed LPS–PMB complex has lower inflammatory activity in blood, which results in highly reduced cytokine secretion. According to in vitro measurements, the appropriate plasma level of PMB for LPS inactivation is between 100 and 200 ng/ml. Furthermore, the combination of cytokine removal by adsorbent treatment with LPS inactivation by PMB dosage leads to strong suppression of inflammatory effects in blood in an in vitro model. Inactivation of endotoxins by low-dose intravenous PMB infusion or infusion into the extracorporeal circuit during blood purification can be applied to overcome the urgent need for endotoxin elimination not only in treatment of sepsis, but also in liver failure.

Inhibition of autophagy ameliorates atherogenic inflammation by augmenting apigenin-induced macrophage apoptosis

Increasing evidences showed that the survival of macrophages promotes atherogenesis. Macrophage apoptosis in the early phase of atherosclerotic process negatively regulates the progression of atherosclerotic lesions. We demonstrated that a natural anti-oxidant apigenin could ameliorate atherogenesis in ApoE(-/-) mice. It reduced the number of foam cells and decreased the serum levels of tumor necrosis factor α, interleukin 1β (IL-1β) and IL-6. Our results showed that oxidized low-density lipoprotein (oxLDL) led to the secretion of pro-inflammatory cytokines. Apigenin-induced apoptosis and downregulated the secretion of TNF-α, IL-6 and IL-1β. It is further supported by the use of zVAD, a pan-caspase inhibitor, demonstrating that apigenin lowered cytokine profile through induction of macrophage apoptosis. Moreover, apigenin-induced Atg5/Atg7-dependent autophagy in macrophages pretreated with oxLDL. Results illustrated that autophagy inhibition increased apigenin-induced apoptosis through activation of Bax. The present findings suggest that oxLDL maintained the survival of macrophages and activated the secretion of pro-inflammatory cytokines to initiate atherosclerosis. Apigenin-induced apoptosis of lipid-laden macrophages and resolved inflammation to ameliorate atherosclerosis. In conclusion, combination of apigenin with autophagy inhibition may be a promising strategy to induce foam cell apoptosis and subdue atherogenic cytokines.

Respiratory syncytial virus fusion protein promotes TLR-4-dependent neutrophil extracellular trap formation by human neutrophils

Acute viral bronchiolitis by Respiratory Syncytial Virus (RSV) is the most common respiratory illness in children in the first year of life. RSV bronchiolitis generates large numbers of hospitalizations and an important burden to health systems. Neutrophils and their products are present in the airways of RSV-infected patients who developed increased lung disease. Neutrophil Extracellular Traps (NETs) are formed by the release of granular and nuclear contents of neutrophils in the extracellular space in response to different stimuli and recent studies have proposed a role for NETs in viral infections. In this study, we show that RSV particles and RSV Fusion protein were both capable of inducing NET formation by human neutrophils. Moreover, we analyzed the mechanisms involved in RSV Fusion protein-induced NET formation. RSV F protein was able to induce NET release in a concentration-dependent fashion with both neutrophil elastase and myeloperoxidase expressed on DNA fibers and F protein-induced NETs was dismantled by DNase treatment, confirming that their backbone is chromatin. This viral protein caused the release of extracellular DNA dependent on TLR-4 activation, NADPH Oxidase-derived ROS production and ERK and p38 MAPK phosphorylation. Together, these results demonstrate a coordinated signaling pathway activated by F protein that led to NET production. The massive production of NETs in RSV infection could aggravate the inflammatory symptoms of the infection in young children and babies. We propose that targeting the binding of TLR-4 by F protein could potentially lead to novel therapeutic approaches to help control RSV-induced inflammatory consequences and pathology of viral bronchiolitis.

The influence of enrofloxacin, florfenicol, ceftiofur and E. coli LPS interaction on T and B cells subset in chicks

This study aimed to investigate the influence of enrofloxacin, florfenicol, ceftiofur and E. coli LPS interaction on T and B subsets in thymus and spleen of newly-hatched chicks. A 126, 1-day-old chicks were administered enrofloxacin, florfenicol or ceftiofur in recommended doses according to the currently treatment schedule advises. E .coli LPS was given intravenously once at the dose of 200 μg kg⁻¹ BW on the 2nd day of experiment (d. e.). On the 6th and the 14th d. e. thymus and spleens were subjected to flow cytometry investigation.

The most significant changes were demonstrated in spleen. The antibiotics administration decreased the percentage of B and T cells subset. Moreover, this suppressive effect was enhanced by E. coli LPS administration. On the 6th d. e. the percentage of CD3⁺TCRγδ⁻, CD3⁺TCRγδ⁺, CD4⁺CD8⁻, CD4⁻CD8⁺ decreased significantly after ceftiofur and LPS treatment. A lower percentage of CD3⁺TCRγδ⁻, CD4⁻CD8⁺ and CD3⁺TCRγδ⁺ was observed in enrofloxacine and LPS treated group. The decrease percentage of CD3⁺TCRγδ⁺cells and Bu-1⁺ was found after florfenicol and LPS treatment. On the 14th d. e. a decreased percentage of CD4⁺CD8⁻ and increased percentage of CD4⁻CD8⁺ cells was shown in ceftiofur or enrofloxacine and LPS treated groups. In addition decreased percentage of CD3⁺TCRγδ⁺ was found in all antibiotic and LPS treated groups.

In this study, it was shown that enrofloxacine, florfenicol, ceftiofur treatment may change the proportions among lymphocytes subset and might have an impact on the immune response to bacterial endotoxins in chicks.

Lipid A-based affinity biosensor for screening anti-sepsis components from herbs

LPS (lipopolysaccharide), an outer membrane component of Gram-negative bacteria, plays an important role in the pathogenesis of sepsis and lipid A is known to be essential for its toxicity. Therefore it could be an effective measure to prevent sepsis by neutralizing or destroying LPS. Numerous studies have indicated that many traditional Chinese medicines are natural antagonists of LPS in vitro and in vivo. The goal of this study is to develop a rapid method to screen anti-sepsis components from Chinese herbs by use of a direct lipid A-based affinity biosensor technology based on a resonant mirror. The detergent OG (n-octyl β-D-glucopyranoside) was immobilized on a planar non-derivatized cuvette which provided an alternative surface to bind the terminal hydrophilic group of lipid A. A total of 78 herbs were screened based on the affinity biosensor with a target of lipid A. The aqueous extract of PSA (Paeonia suffruticosa Andr) was found to possess the highest capability of binding lipid A. Therefore an aqueous extraction from this plant was investigated further by our affinity biosensor, polyamide chromatography and IEC–HPLC. Finally, we obtained a component (PSA-I-3) from Paeonia suffruticosa Andr that was evaluated with the affinity biosensor. We also studied the biological activities of PSA-I-3 against sepsis in vitro and in vivo to further confirm the component we screened with the biosensor. In vitro, we found that PSA-I-3 could decrease TNFα (tumour necrosis factor α) release from RAW264.7 cells induced by LPS in a dose-dependent manner. In vivo, it increased remarkably the survival of KM (KunMing) mice by challenging both lethal-dose LPS and heat-killed Escherichia coli compared with control groups. Our results suggest that the constructed affinity biosensor can successfully screen the anti-sepsis component from Chinese herbs.

Crosstalk between adrenergic and toll-like receptors in human mesenchymal stem cells and keratinocytes: a recipe for impaired wound healing

Previous studies demonstrate that skin wounds generate epinephrine (EPI) that can activate local adrenergic receptors (ARs), impairing healing. Bacterially derived activators of Toll-like receptors (TLRs) within the wound initiate inflammatory responses and can also impair healing. In this study, we examined the hypothesis that these two pathways crosstalk to one another, using EPI and macrophage-activating lipopeptide-2 (MALP2) to activate ARs and TLR2, respectively, in human bone marrow-derived mesenchymal stem cells (BM-MSCs) and neonatal keratinocytes (NHKs). BM-MSCs exposed to EPI significantly (p < .05) increased TLR2 message (sevenfold BM-MSCs), TLR2 protein (twofold), and myeloid differentiation factor 88 (MyD88) (fourfold). Conversely, activation of TLR2 by MALP2 in these cells increased β2-AR message (twofold in BM-MSCs, 2.7-fold in NHKs), β2-AR protein (2.5-fold), phosphorylation of β-AR-activated kinase (p-BARK, twofold), and induced release of EPI from both cell types (twofold). Treating cells with EPI and MALP2 together, as would be encountered in a wound, increased β2-AR and p-BARK protein expression (sixfold), impaired cell migration (BM-MSCs- 21%↓ and NHKs- 60%↓, p < .002), and resulted in a 10-fold (BM-MSCs) and 51-fold (NHKs) increase in release of IL-6 (p < .001) responses that were remarkably reduced by pretreatment with β2-AR antagonists. In vivo, EPI-stressed animals exhibited impaired healing, with elevated levels of TLR2, MyD88, and IL-6 in the wounds (p < .05) relative to nonstressed controls. Thus, our data describe a recipe for decreasing cell migration and exacerbating inflammation via novel crosstalk between the adrenergic and Toll-like receptor pathways in BM-MSCs and NHKs.

Honey: an immunomodulator in wound healing

Honey is a popular natural product that is used in the treatment of burns and a broad spectrum of injuries, in particular chronic wounds. The antibacterial potential of honey has been considered the exclusive criterion for its wound healing properties. The antibacterial activity of honey has recently been fully characterized in medical-grade honeys. Recently, the multifunctional immunomodulatory properties of honey have attracted much attention. The aim of this review is to provide closer insight into the potential immunomodulatory effects of honey in wound healing. Honey and its components are able to either stimulate or inhibit the release of certain cytokines (tumor necrosis factor-α, interleukin-1β, interleukin-6) from human monocytes and macrophages, depending on wound condition. Similarly, honey seems to either reduce or activate the production of reactive oxygen species from neutrophils, also depending on the wound microenvironment. The honey-induced activation of both types of immune cells could promote debridement of a wound and speed up the repair process. Similarly, human keratinocytes, fibroblasts, and endothelial cell responses (e.g., cell migration and proliferation, collagen matrix production, chemotaxis) are positively affected in the presence of honey; thus, honey may accelerate reepithelization and wound closure. The immunomodulatory activity of honey is highly complex because of the involvement of multiple quantitatively variable compounds among honeys of different origins. The identification of these individual compounds and their contributions to wound healing is crucial for a better understanding of the mechanisms behind honey-mediated healing of chronic wounds.

Non-typhoidal Salmonella encephalopathy involving lipopolysaccharide in cattle

This study assessed the involvement of lipopolysaccharide (LPS) in the non-typhoidal Salmonella encephalopathy (NTSE) caused by a unique isolate of Salmonella enterica serovar Saint-paul (SstpNPG). NTSE was prevented by genetic (deletion of murE) or pharmacologic (polymyxin) disruption of LPS on SstpNPG although the disruption of LPS did not deter brain penetration of the strain. This is the first study to demonstrate that LPS is involved in the manifestations of NTSE.

Removal of increased circulating CD4+CD25+Foxp3+ regulatory T cells in patients with septic shock using hemoperfusion with polymyxin B-immobilized fibers

BACKGROUND

Although sepsis-induced immunosuppression has long been considered to be a factor in the late mortality of patients with sepsis, little is known about regulatory T cell (Treg)-mediated immunosuppression and the effect of polymyxin B-immobilized fiber (PMX-F) on sepsis-induced immunosuppression. We sought to investigate the role of CD4(+)CD25(+)Foxp3(+) Tregs in septic patients, and to evaluate the effect of hemoperfusion with PMX-F on the recovery from immunosuppression owing to septic shock.

METHODS

Thirty-two septic patients who had an identified focus of infection in the abdominal cavity were enrolled in this study. Peripheral blood mononuclear cells in the septic patients were examined to evaluate the roles of Tregs and the serum cytokine levels. We also examined the effects of PMX-F therapy on CD4(+) T cells, especially Tregs and serum cytokine levels in patients with septic shock.

RESULTS

The percentage of Tregs in the CD4(+) T-cell population, and the serum IL-6 and IL-10 levels, were significantly higher among patients with septic shock compared with those without septic shock, and PMX-F therapy significantly decreased the number of Tregs, as well as the serum IL-6 and IL-10 levels. Furthermore, a significant increase in the number of CD4(+) T cells, a significant decrease in the percentage of Tregs in the CD4(+) T-cell population, and a significant decrease in the serum IL-6 and IL-10 levels 24 hours after PMX-F therapy were observed in septic shock survivors compared with nonsurvivors.

CONCLUSION

We found a major increase in the percentage of Tregs in peripheral blood circulating CD4(+) T cells from patients with septic shock, and observed that the removal of Tregs by hemoperfusion with PMX-F might represent a novel strategy for inducing recovery from the immunosuppression associated with sepsis.

Respiratory syncytial virus fusion protein-induced toll-like receptor 4 (TLR4) signaling is inhibited by the TLR4 antagonists Rhodobacter sphaeroides lipopolysaccharide and eritoran (E5564) and requires direct interaction with MD-2

Respiratory syncytial virus (RSV) is a leading cause of infant mortality worldwide. Toll-like receptor 4 (TLR4), a signaling receptor for structurally diverse microbe-associated molecular patterns, is activated by the RSV fusion (F) protein and by bacterial lipopolysaccharide (LPS) in a CD14-dependent manner. TLR4 signaling by LPS also requires the presence of an additional protein, MD-2. Thus, it is possible that F protein-mediated TLR4 activation relies on MD-2 as well, although this hypothesis has not been formally tested. LPS-free RSV F protein was found to activate NF-κB in HEK293T transfectants that express wild-type (WT) TLR4 and CD14, but only when MD-2 was coexpressed. These findings were confirmed by measuring F-protein-induced interleukin 1β (IL-1β) mRNA in WT versus MD-2(-/-) macrophages, where MD-2(-/-) macrophages failed to show IL-1β expression upon F-protein treatment, in contrast to the WT. Both Rhodobacter sphaeroides LPS and synthetic E5564 (eritoran), LPS antagonists that inhibit TLR4 signaling by binding a hydrophobic pocket in MD-2, significantly reduced RSV F-protein-mediated TLR4 activity in HEK293T-TLR4-CD14-MD-2 transfectants in a dose-dependent manner, while TLR4-independent NF-κB activation by tumor necrosis factor alpha (TNF-α) was unaffected. In vitro coimmunoprecipitation studies confirmed a physical interaction between native RSV F protein and MD-2. Further, we demonstrated that the N-terminal domain of the F1 segment of RSV F protein interacts with MD-2. These data provide new insights into the importance of MD-2 in RSV F-protein-mediated TLR4 activation. Thus, targeting the interaction between MD-2 and RSV F protein may potentially lead to novel therapeutic approaches to help control RSV-induced inflammation and pathology.

IMPORTANCE

This study shows for the first time that the fusion (F) protein of respiratory syncytial virus (RSV), a major cause of bronchiolitis and death, particularly in infants and young children, physically interacts with the Toll-like receptor 4 (TLR4) coreceptor, MD-2, through its N-terminal domain. We show that F protein-induced TLR4 activation can be blocked by lipid A analog antagonists. This observation provides a strong experimental rationale for testing such antagonists in animal models of RSV infection for potential use in people.

The Effect of Acupuncture on Proinflammatory Cytokine Production in Patients with Chronic Headache: A Preliminary Report

Acupuncture has been widely used as a treatment for various conditions like headache and stroke, especially in Asian countries such as Korea and China. But few scientific investigations have been carried out. The aim of the present study is to investigate the effect of acupuncture on the production of inflammatory cytokines in patients with chronic headache (CH). Patients with CH were treated with acupuncture during the acute stage. Clinical signs of CH disappeared markedly after three months of treatment with acupuncture. Peripheral blood mononuclear cells obtained from a normal group and those from the patients with CH, before and after treatment with acupuncture, were cultured for 24 hours in the presence or absence of lipopolysaccharide (LPS). The amount of interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α) in LPS culture supernatant was significantly increased in the patients with CH compared to the healthy control group (p < 0.05). But those cytokines came down toward the levels of the healthy group (p < 0.05) after treatment with acupuncture, although the levels still remained elevated. Plasma cytokine levels were analyzed to evaluate any change due to acupuncture treatment. There was little difference in the levels of IL-1β or IL-6 due to the treatment with acupuncture in the patients with CH, but significantly reduced plasma levels of TNF-α were observed. These data suggest that acupuncture treatment has an inhibitory effect on pro-inflammatory cytokine production in patients with CH.

Pulmonary T cell activation in response to chronic particulate air pollution

The purpose of this study was to investigate the effects of chronically inhaled particulate matter <2.5 μm (PM(2.5)) on inflammatory cell populations in the lung and systemic circulation. A prominent component of air pollution exposure is a systemic inflammatory response that may exaggerate chronic diseases such as atherosclerosis and insulin resistance. T cell response was measured in wild-type C57B/L6, Foxp3-green fluorescent protein (GFP) "knockin," and chemokine receptor 3 knockout (CXCR3(-/-)) mice following 24-28 wk of PM(2.5) or filtered air. Chronic PM(2.5) exposure resulted in increased CXCR3-expressing CD4(+) and CD8(+) T cells in the lungs, spleen, and blood with elevation in CD11c(+) macrophages in the lung and oxidized derivatives of 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphorylcholine in wild-type mice. CXCR3 deficiency decreased T cells in the lung. GFP(+) regulatory T cells increased with PM(2.5) exposure in the spleen and blood of Foxp3-GFP mice but were present at very low levels in the lung irrespective of PM(2.5) exposure. Mixed lymphocyte cultures using primary, PM(2.5)-treated macrophages demonstrated enhanced T cell proliferation. Our experiments indicate that PM(2.5) potentiates a proinflammatory Th1 response involving increased homing of CXCR3(+) T effector cells to the lung and modulation of systemic T cell populations.

Consequences of alteration in leucine zipper sequence of melittin in its neutralization of lipopolysaccharide-induced proinflammatory response in macrophage cells and interaction with lipopolysaccharide

The bee venom antimicrobial peptide, melittin, besides showing versatile activity against microorganisms also neutralizes lipopolysaccharide (LPS)-induced proinflammatory responses in macrophage cells. However, how the amino acid sequence of melittin contributes in its anti-inflammatory properties is mostly unknown. To determine the importance of the leucine zipper sequence of melittin in its neutralization of LPS-induced inflammatory responses in macrophages and interaction with LPS, anti-inflammatory properties of melittin and its three analogues and their interactions with LPS were studied in detail. Two of these analogues, namely melittin Mut-1 (MM-1) and melittin Mut-2 (MM-2), possess leucine to alanine substitutions in the single and double heptadic leucine residue(s) of melittin, respectively, whereas the third analogue is a scrambled peptide (Mel-SCR) that contains the amino acid composition of melittin with minor rearrangement in its leucine zipper sequence. Although MM-1 partly inhibited the production of proinflammatory cytokines in RAW 264.7 and rat primary macrophage cells in the presence of LPS, MM-2 and Mel-SCR were negligibly active. A progressive decrease in interaction of melittin with LPS, aggregation in LPS, and dissociation of LPS aggregates with alteration in the leucine zipper sequence of melittin was observed. Furthermore, with alteration in the leucine zipper sequence of melittin, these analogues failed to exhibit cellular responses associated with neutralization of LPS-induced inflammatory responses in macrophage cells by melittin. The data indicated a probable important role of the leucine zipper sequence of melittin in neutralizing LPS-induced proinflammatory responses in macrophage cells as well as in its interaction with LPS.

Apheresis of activated leukocytes with an immobilized polymyxin B filter in patients with septic shock

In this study, we examined the effects of direct hemoperfusion through filters with immobilized polymyxin B (PMX-DHP) on leukocyte function and plasma levels of cytokines in patients with septic shock. We found that PMX-DHP caused increased expression of C-X-C chemokine receptor 1 (CXCR1) and CXCR2, along with decreased expression of CD64 and CD11b, by circulating neutrophils in patients with septic shock. Plasma levels of cytokines, including interleukin 6 (IL-6), IL-8, IL-10, and high-mobility group box 1, were elevated in patients with septic shock compared with healthy controls, but cytokine levels were not altered by PMX-DHP. These results suggest that PMX-DHP influences neutrophils via a mechanism that does not involve cytokine. Ex vivo perfusion of heparinized blood from patients with sepsis and septic shock through PMX filters in a laboratory circuit caused a significant decrease in neutrophil and monocyte counts. After 120 min of perfusion, neutrophils, monocytes, and lymphocytes were decreased by 78%, 70%, and 10%, respectively, compared with baseline values. Flow cytometric analysis indicated that activated neutrophils with high levels of CD11b/CD64 expression and low levels of CXCR1/CXCR2 expression showed preferential adhesion to PMX filters. Neutrophils isolated from the blood after ex vivo PMX perfusion caused less damage to an endothelial cell monolayer than cells from sham-treated blood, whereas neutrophil phagocytosis of opsonized Escherichia coli was unaffected. These results indicate that PMX-DHP selectively removes activated neutrophils and reduces the ability of circulating cells to cause endothelial damage. Selective removal of activated neutrophils using PMX-DHP may improve the systemic inflammatory response in patients with septic shock.

Lipopolysaccharide (LPS) detoxification of analogue peptides derived from limulus anti-LPS factor

Lipopolysaccharide (LPS) plays a critical role in the pathogenesis of sepsis due to gram-negative bacterial infections. Therefore, LPS-neutralizing molecules could have important clinical applications. Our previous work showed, CLP19, an analogue peptide derived from limulus anti-LPS factor (LALF), possessed the capacity to neutralize LPS and thereby inhibit the LPS-induced responses. However, potential cytotoxicity of CLP19 was also found, especially when added to human red blood cells. Accordingly we further developed two peptides (designated as CLP19-1 and CLP19-2) by single- and double-point amino acid substitution of CLP19, respectively, in order to reduce its toxicity and meanwhile retain the anti-LPS activity. In this study, the LPS-detoxifying effectiveness of these peptides was evaluated both in vitro and in vivo. CLP19-1 was found to dose-dependently neutralize LPS in vitro, with significantly lower hemolysis of red blood cells as compared with CLP19. Further in vivo tests verified that CLP19-1 exerted significant protective effects on mice against LPS, characterized by significantly improved survival, decreasing of tumor necrosis factor alpha (TNF-α) serum level and alleviation of tissue injury. Our work indicates that CLP19-1 is worthy of further study as potential anti-LPS agents for the management of sepsis.

Evaluation of the anti-endotoxin effects of polymyxin B in a feline model of endotoxemia

Directed, effective therapies for feline sepsis are needed to reduce the high morbidity and mortality associated with this disease. We investigated the anti-endotoxin effects of polymyxin B (PMB) in a blinded, placebo controlled fashion, both ex vivo in a feline whole blood culture system and in vivo, using a low-dose endotoxin infusion in cats. Serial measures of systemic inflammation, and hemodynamic stability, were compared between groups. Ex vivo, PMB significantly decreased lipopolysaccharide-induced tumor necrosis factor (TNF) production from whole blood. PMB (1mg/kg over 30min) demonstrated anti-endotoxin effects in vivo, including decreased peak plasma TNF activity (P<0.001) and increased white blood cell count (P=0.019), with no adverse effects. Given the apparent safety and anti-endotoxin effects of PMB in this endotoxemia model, a carefully designed, randomized, blinded, placebo controlled clinical trial evaluating the use of PMB in naturally occurring Gram-negative feline sepsis should be considered.

Polymyxin B protects horses against induced endotoxaemia in vivo

REASONS FOR PERFORMING STUDY

A safe, affordable and effective treatment for endotoxaemia in horses is needed in order to reduce the incidence of this potentially fatal condition.

OBJECTIVE

To evaluate the effect of polymyxin B (PMB) on signs of experimentally-induced endotoxaemia.

HYPOTHESIS

PMB ameliorates the adverse effects of endotoxaemia without causing nephrotoxicity.

METHODS

Four groups of 6 healthy mature horses each received 20 ng endotoxin/kg bwt i.v. over 30 mins. Additionally, each group received one of the following i.v.; 5000 u PMB/kg bwt 30 mins before endotoxin infusion; 5000 u PMB/kg bwt 30 mins after endotoxin infusion; 1000 u PMB/kg bwt 30 mins prior to endotoxin infusion; or saline. Clinical response data and samples were collected to determine neutrophil count, serum tumour necrosis factor (TNF) activity, plasma thromboxane B2 concentration and urine gamma glutamyltranspeptidase (GGT) to creatinine ratio.

RESULTS

Treatment with PMB before or after administration of endotoxin significantly reduced fever, tachycardia and serum TNF, compared to horses receiving saline. The differences in response to endotoxin were greatest between horses that received saline vs. those that received 5000 u PMB/kg bwt prior to endotoxin. Urine GGT:creatinine did not change significantly.

CONCLUSIONS AND POTENTIAL RELEVANCE

This study indicates that PMB may be a safe and effective treatment of endotoxaemia, even when administered after onset. Although nephrotoxicity was not demonstrated with this model, caution should be exercised when using PMB in azotaemic patients.

Hemoperfusion with polymyxin B-immobilized fiber column improves liver function after ischemia-reperfusion injury

AIM: To investigate the usefulness of direct hemoperfusion with a polymyxin B-immobilized fiber column (DHP-PMX therapy) for warm hepatic ischemia-reperfusion (I/R) injury after total hepatic vascular exclusion (THVE) using a porcine model.

METHODS: Eleven Mexican hairless pigs weighing 22-38 kg were subjected to THVE for 120 min and then observed for 360 min. The animals were divided into two groups randomly: the DHP-PMX group (n = 5) underwent DHP-PMX at a flow rate of 80 mL/min for 120 min (beginning 10 min before reperfusion), while the control group did not (n = 6). The rate pressure product (RPP): heart rate × end-systolic arterial blood pressure, hepatic tissue blood flow (HTBF), portal vein blood flow (PVBF), and serum aspartate aminotransferase (AST) levels were compared between the two groups.

RESULTS: RPP and HTBF were significantly (P < 0.05) higher in the DHP-PMX group than in the control group 240 and 360 min after reperfusion. PVBF in the DHP-PMX group was maintained at about 70% of the flow before ischemia and differed significantly (P < 0.05) compared to the control group 360 min after reperfusion. The serum AST increased gradually after reperfusion in both groups, but the AST was significantly (P < 0.05) lower in the DHP-PMX group 360 min after reperfusion.

CONCLUSION: DHP-PMX therapy reduced the hepatic warm I/R injury caused by THVE in a porcine model.

INHIBITORY EFFECT OF YANGKYUK-SANHWA-TANG ON INFLAMMATORY CYTOKINE PRODUCTION IN PERIPHERAL BLOOD MONONUCLEAR CELLS FROM THE CEREBRAL INFARCTION PATIENTS

Yangkyuk-Sanhwa-Tang (YST) has been used for the Soyangin cerebral infarction (CI) patients according to Sasang constitutional philosophy. This study investigated the effect of YST on production of various cytokines using peripheral blood mononuclear cells (PBMCs) from the Soyangin CI patients group. The amount of interleukin (IL)-1alpha, IL-1beta, IL-6, IL-8, and tumor necrosis factor-alpha increased in the lipopolysaccharide (LPS)-treated cells compared with unstimulated-cells. YST inhibited IL-1alpha, IL-1beta, and IL-8 production in PBMCs stimulated with LPS. These data suggest that YST has a regulatory effect on cytokine production, which might explain its beneficial effect in the treatment of Soyangin CI patients.

Different effects of telithromycin on MUC5AC production induced by human neutrophil peptide-1 or lipopolysaccharide in NCI-H292 cells compared with azithromycin and clarithromycin

OBJECTIVES

Mucus hypersecretion is a prominent feature in patients with chronic respiratory tract infections such as cystic fibrosis and diffuse panbronchiolitis, and the clinical effectiveness of macrolide antibiotics has been reported in these patients. Because human neutrophil peptide-1 (HNP-1), an antimicrobial peptide in neutrophils, exists in high concentrations in the airway fluid of these patients, we examined the direct effect of HNP-1 on MUC5AC mucin production using NCI-H292 cells. The effects of macrolide antibiotics on the response were also examined.

METHODS

MUC5AC synthesis was assayed using RT-PCR and ELISA. Phosphorylation of ERK1/2 was determined by western blotting.

RESULTS

Stimulation with HNP-1 or lipopolysaccharide (LPS) derived from Pseudomonas aeruginosa increases the production of MUC5AC mRNA and protein, and an additive effect was found upon co-stimulation with both HNP-1 and LPS. Azithromycin and clarithromycin had inhibitory effects on overproduction of MUC5AC induced by HNP-1 or LPS stimulation. Telithromycin also had an inhibitory effect on MUC5AC production induced by LPS, but not on production by HNP-1. Phosphorylation of ERK1/2 was induced by HNP-1 or LPS stimulation, and azithromycin, clarithromycin and telithromycin had inhibitory effects on ERK1/2 phosphorylation induced by LPS, but not by HNP-1.

CONCLUSIONS

These findings suggest that neutrophil-derived defensins as bacterial components contribute to excessive mucus production in patients with respiratory tract infections, and that macrolide and ketolide antibiotics directly inhibit these actions by interfering with intracellular signal transduction. However, the mechanism of telithromycin inhibition of MUC5AC synthesis may differ from the response induced by azithromycin and clarithromycin.

Direct hemoperfusion with a polymyxin B-immobilized cartridge in intestinal warm ischemia reperfusion

AIM: To investigate the effectiveness of direct hemoperfusion with polymyxin B-immobilized fibers (DHP-PMX therapy) on warm ischemia-reperfusion (I/R) injury of the small intestine.

METHODS: The proximal jejunum and distal ileum of mongrel dogs were resected. Warm ischemia was performed by clamping the superior mesenteric artery (SMA) and vein (SMV) for 2 h. Blood flow to the proximal small intestine was restored 1 h after reperfusion, and the distal small intestine was used as a stoma. The experiment was discontinued 6 h after reperfusion. The dogs were divided into two groups: the DHP-PMX group (n = 6, DHP-PMX was performed for 180 min; from 10 min prior to reperfusion to 170 min after reperfusion) and the control group (n = 5). The rate pressure product (RPP), SMA blood flow, mucosal tissue blood flow, and intramucosal pH (pHi) were compared between the two groups. The serum interleukin (IL)-10 levels measured 170 min after reperfusion were also compared.

RESULTS: The RPP at 6 h after reperfusion was significantly higher in the PMX group than in the control group (12 174 ± 1832 mmHg/min vs 8929 ± 1797 mmHg/min, P < 0.05). The recovery rates of the SMA blood flow at 1 and 6 h after reperfusion were significantly better in the PMX group than in the control group (61% ± 7% vs 44% ± 4%, P < 0.05, and 59% ± 5% vs 35% ± 5%, P < 0.05, respectively). The recovery rate of the mucosal tissue blood flow and the pHi levels at 6 h after reperfusion were significantly higher in the PMX group (61% ± 8% vs 31% ± 3%, P < 0.05 and 7.91 ± 0.06 vs 7.69 ± 0.08, P < 0.05, respectively). In addition, the serum IL-10 levels just before DHP-PMX removal were significantly higher in the PMX group than in the control group (1 569 ± 253 pg/mL vs 211 ± 40 pg/mL, P < 0.05).

CONCLUSION: DHP-PMX therapy reduced warm I/R injury of the small intestine. IL-10 may play a role in inhibiting I/R injury during DHP-PMX therapy.

Direct hemoperfusion with polymyxin-B-immobilized fiber columns improves septic hypotension and reduces inflammatory mediators in septic patients with colorectal perforation

PURPOSE

Although some studies have reported favorable effects of direct hemoperfusion with polymyxin-B-immobilized fiber columns (PMX) for the treatment of septic shock, few studies have demonstrated the efficacy of PMX in studies with a uniform case definition and without any other blood purification techniques.

MATERIALS AND METHODS

Fifty-two patients with severe sepsis or septic shock secondary to colorectal perforation were treated with PMX. Hemodynamic alterations and plasma concentrations of endotoxin, interleukin (IL)-1beta, IL-1 receptor antagonist (IL-1Ra), IL-6, IL-8, and IL-10 were evaluated following PMX treatment.

RESULTS

We observed a significant reduction in plasma endotoxin in the nonsurvivors immediately after PMX treatment compared to before treatment. Systolic blood pressure was markedly increased and circulating levels of IL-1beta, IL-1Ra, and IL-8 were significantly reduced during a 2-h interval of PMX.

CONCLUSIONS

Our findings suggested that PMX treatment appears to adsorb endotoxin and also modulates circulating cytokine during a 2-h interval of direct hemoperfusion in septic patients with such condition.

The effect of direct hemoperfusion with a polymyxin B-immobilized fiber column (DHP-PMX therapy) on pulmonary ischemia-reperfusion injury in a canine model

This study evaluates the effectiveness of direct hemoperfusion with a polymyxin B-immobilized fiber column (DHP-PMX therapy) on warm ischemia-reperfusion injury of the lung using a canine mode.

MATERIALS AND METHODS

Ten adult mongrel dogs weighing 13-16 kg were used. After a left thoracotomy, the left pulmonary artery and vein were clamped. The left main bronchus was also clamped and then divided, and complete ischemia of the left lung was maintained for 3 h. The left main bronchus was re-anastomosed before reperfusion of the left lung. The right pulmonary artery was ligated immediately after reperfusion of the left lung. The dogs were divided into two groups: the DHP-PMX group (n = 5, DHP-PMX was performed for 120 min, from 30 min before reperfusion to 90 min after reperfusion) and the control group (n = 5). The body temperature of the animals was maintained at 36 degrees C-37 degrees C during the experiment. The PaO2/FiO2 (P/F ratio), AaDO2, and lt-pulmonary vascular resistance (PVR) were measured at 30, 60, 120, 180, and 240 min after reperfusion in both groups, and the two groups were compared. The water content of the lung tissues and histopathology was also analyzed.

RESULTS

The P/F ratio decreased remarkably after reperfusion in the control group, and was significantly (p < .05) lower than that in the PMX-DHF group until 240 min after reperfusion. The AaDO2 was significantly (p < .05) lower in the DHP-PMX group than in the control group at 30, 60, and 120 min after reperfusion. The lt-PVR level differed significantly (p < .05) between the two groups until 240 min after reperfusion. The water content in the control group was significantly (p < .05) higher than that in the DHP-PMX group at 240 min after reperfusion. Lung tissues at 120 and 240 min after reperfusion were better preserved pathologically in the DHP-PMX group.

CONCLUSION

DHP-PMX therapy reduced warm ischemia-reperfusion injury in the lung using a canine model.

Immunomodulatory capacity of fungal proteins on the cytokine production of human peripheral blood mononuclear cells

Immunomodulation by fungal compounds can be determined by the capacity of the compounds to influence the cytokine production by human peripheral blood mononuclear cells (hPBMC). These activities include mitogenicity, stimulation and activation of immune effector cells. Eight mushroom strains (Agaricus blazei, Coprinus comatus, Flammulina velutipes, Ganoderma lucidum, Grifola frondosa, Volvariella volvacea, Lentinus edodes, and Pleurotus ostreatus) were tested for the immunomodulating activity of the isolated protein fractions and polysaccharides fractions present in mycelia and culture liquid. The fungal proteins and polysaccharides have been investigated for their in vitro effect on the cytokine profile (IFN-gamma, IL-4, IL-10, IL-12 and TNF-alpha) of unstimulated or hPBMC stimulated with the polyclonal stimulations PMA/Ca-I, ConA or LPS. In addition to their influence on the cytokine profile, the hemagglutination activity of the fungal proteins on rabbit red blood cells was determined. Proteins from V. volvacea and G. lucidum showed immunomodulating activity without the presence of any mitogen, however, neither of them decreased the production of IL-4 and IFN-gamma in combination with a stimulus. All used stimuli resulted in an induction of IL-12 in the presence of the protein extracts, suggesting a direct effect on monocytes. This effect might lead to the indirect immunomodulation of T cell activation and cytokine production. In addition, both protein extracts showed more hemagglutination activity after trypsin treatment of the rabbit red blood cells, indicating the presence of carbohydrate-binding proteins, like lectins and FIPs. In conclusion, the protein extracts of V. volvacea and G. lucidum contain immunomodulating activity by acting directly on monocytes and thereby modulating T cell activation. Further purification of the fungal extracts is needed to clarify whether there are FIPs or lectins present that are responsible for this immunomodulating activity.

Mucosal IL-10 and TGF-beta play crucial roles in preventing LPS-driven, IFN-gamma-mediated epithelial damage in human colon explants

IL-10 is an immunomodulatory cytokine that plays an obligate role in preventing spontaneous enterocolitis in mice. However, little is known about IL-10 function in the human intestinal mucosa. We showed here that IL-10 was constitutively expressed and secreted by the human normal colonic mucosa, including epithelial cells. Depletion of IL-10 in mucosal explants induced both downregulation of the IL-10-inducible, immunosuppressive gene BCL3 and upregulation of IFN-gamma, TNF-alpha, and IL-17. Interestingly, TGF-beta blockade also strongly induced IFN-gamma production. In addition, the high levels of IFN-gamma produced upon IL-10 depletion were responsible for surface epithelium damage and crypt loss, mainly by apoptosis. Polymyxin B, used as a scavenger of endogenous LPS, abolished both IFN-gamma production and epithelial barrier disruption. Finally, adding a commensal bacteria strain to mucosa explant cultures depleted of both IL-10 and LPS reproduced the ability of endogenous LPS to induce IFN-gamma secretion. These findings demonstrate that IL-10 ablation leads to an endogenous IFN-gamma-mediated inflammatory response via LPS from commensal bacteria in the human colonic mucosa. We also found that both IL-10 and TGF-beta play crucial roles in maintaining human colonic mucosa homeostasis.