ROS-triggered nanoinducer based on dermatan sulfate enhances immunogenic cell death in melanoma.

Due to its complexity, diversity and heterogeneity, melanoma is a kind of malignant tumor. It has been proved that the enhancement of anti-tumor immune response such as immunogenic cell death (ICD) is an important therapeutic strategy. In previous studies, we confirmed that dermatan sulfate (DS) from skin tissue could specifically homing to melanoma B16F10 cells. In this study, we propose a nanoinducer (DOX/ADS NP) based on a functional DS for melanoma. This nanosystem is composed of DS as framework, aromatic thioketal derivative (ATK) as functional grafting unit and doxorubicin (DOX) designed as an ICD inducer. Through the intermolecular interaction between DOX and ATK, DOX/ADS NP with specific-homing, high-loading and ROS-triggering release was obtained via self-assemble. Compared with free DOX and non-functionalized nanomedicine, DOX/ADS NP could release DOX into B16F10 cells better, and strongly induce the translocation of calreticulin (CRT) to the cell membrane. CRT is a marker of ICD, also as a "eat me" signal to stimulate the maturation and antigen presentation of dendritic cells. Therefore, a series of subsequent immune responses were activated: maturation of dendritic cells, T cells proliferation, increased tumor-infiltrating CTLs and the ratio of CTLs to Tregs, and up-regulated cytotoxic cytokine expression. In conclusion, DOX/ADS NP promoted ICD-associated immune response through more specific targeting effect and sensitive responsive DOX release, achieving better inhibitory effect on melanoma than free DOX and other nanoformulation. This biomimetic ICD nanoinducer based on DS is expected to provide new strategies and references for the treatment of melanoma.

Epigallocatechin-3-gallate attenuates acute pancreatitis induced lung injury by targeting mitochondrial reactive oxygen species triggered NLRP3 inflammasome activation.

Green tea has been considered as a health-promoting beverage and is widely consumed worldwide. Epigallocatechin-3-gallate (EGCG), the most abundant polyphenol derived from green tea leaves with potent antioxidative and chemopreventive activities, has been reported to offer protection against inflammation-driven tissue damage. Here, we evaluated the protective effects of EGCG against lung injury during acute pancreatitis (AP) and further revealed the detailed mechanism. The results showed that EGCG significantly attenuated l-arginine-induced AP and the consequent pulmonary damage in mice. Moreover, EGCG substantially attenuated oxidative stress and concurrently suppressed NOD-like receptor protein 3 (NLRP3) inflammasome activation in the lung. In vitro, EGCG considerably reduced the production of mitochondrial reactive oxygen species (mtROS) and oxidized mitochondrial DNA (ox-mtDNA) in alveolar macrophages (AMs) challenged with AP-conditioned plasma. Meanwhile, the amount of ox-mtDNA bound to NLRP3 decreased significantly by the treatment with EGCG, resulting in impaired NLRP3 inflammasome activation. In addition, the antagonism of NLRP3 signaling by EGCG was affected in the presence of the mtROS stimulant rotenone or scavenger Mito-TEMPO. Altogether, EGCG possesses potent activity to attenuate lung injury during AP progression by inhibiting NLRP3 inflammasome activation. As for the mechanism, the EGCG-conferred restriction of NLRP3 inflammasome activation probably arises from the elimination of mtROS as well as its oxidative product ox-mtDNA, which consequently enables the protection against AP-associated lung injury.

Mangiferin loaded magnetic PCEC microspheres: preparation, characterization and antitumor activity studies in vitro.

Mangiferin is a promising effective chemopreventive agent against various tumors. However, its clinical use is limited by poor water solubility and low bioavailability. In this article, mangiferin loaded magnetic PCEC microspheres (MG-MS) were designed, characterized and the antitumor activity of MG-MS was evaluated in vitro. The magnetic nanoparticles (MNP) were synthesized via the high-temperature reaction of iron acetylacetonate in phenyl ether in the presence of oleic acid and oleylamine. Poly (ε-caprolactone)-poly (ethyleneglycol)-poly (ε-caprolactone) (PCL-PEG-PCL, PCEC) copolymers were formed by ring-opening copolymerization of ε-CL initiated by PEG-diol using Sn(Oct)2 as a catalyst and MG-MS were prepared by solvent diffusion method. MNP, PCEC copolymer, and MG-MS were characterized by GPC, TEM, XRD, FT-IR, 1H-NMP and Malvern Laser Particle Sizer. Meanwhile, the antiproliferative activity in vitro and in vitro release behavior of this microspheres were studied in detail. The results indicate that the obtained magnetic microspheres might have great potential as an effective carrier for mangiferin used in cancer chemotherapy.

The Role of Exogenous Hydrogen Sulfide in Free Fatty Acids Induced Inflammation in Macrophages.

BACKGROUND: This study aimed to investigate whether exogenous hydrogen sulfide (H2S) can protect the RAW264.7 macrophages against the inflammation induced by free fatty acids (FFA) by blunting NLRP3 inflammasome activation via a specific TLR4/NF-κB pathway. METHODS: RAW264.7 macrophages were exposed to increasing concentrations of FFA for up to 3 days to induce FFA-induced inflammation. The cells were pretreated with NaHS (a donor of H2S) before exposure to FFA. Cell viability, cell apoptosis, TLR4, NF-κB, NLRP3 inflammasome, IL-1ß, IL-18 and cleaved caspase-3 expression were measured by a combination of MTT assay, ELISA, and immunoblotting. RESULTS: H2S attenuated FFA-induced cell apoptosis, and reduced the expression of NLRP3, ASC, pro-caspase-1, caspase-1, IL- 1ß, IL-18 and caspase-3. In addition, H2S inhibited the FFA-induced activation of TLR4 and NF-κB. Furthermore, NLRP3 inflammasome activation was regulated by the TLR4 and NF-κB pathway. CONCLUSION: The present study demonstrated for the first time that H2S appears to suppress FFA-induced macrophage inflammation and apoptosis by inhibiting the TLR4/ NF-κB pathway and its downstream NLRP3 inflammasome activation. Thus H2S might possess potential in the treatment of diseases resulting from FFA overload like insulin resistance and type diabetes.

Molecular hydrogen inhibits lipopolysaccharide-triggered NLRP3 inflammasome activation in macrophages by targeting the mitochondrial reactive oxygen species.

The NLRP3 inflammasome, an intracellular multi-protein complex controlling the maturation of cytokine interleukin-1ß, plays an important role in lipopolysaccharide (LPS)-induced inflammatory cascades. Recently, the production of mitochondrial reactive oxygen species (mtROS) in macrophages stimulated with LPS has been suggested to act as a trigger during the process of NLRP3 inflammasome activation that can be blocked by some mitochondria-targeted antioxidants. Known as a ROS scavenger, molecular hydrogen (H2) has been shown to possess therapeutic benefit on LPS-induced inflammatory damage in many animal experiments. Due to the unique molecular structure, H2 can easily target the mitochondria, suggesting that H2 is a potential antagonist of mtROS-dependent NLRP3 inflammasome activation. Here we have showed that, in mouse macrophages, H2 exhibited substantial inhibitory activity against LPS-initiated NLRP3 inflammasome activation by scavenging mtROS. Moreover, the elimination of mtROS by H2 resultantly inhibited mtROS-mediated NLRP3 deubiquitination, a non-transcriptional priming signal of NLRP3 in response to the stimulation of LPS. Additionally, the removal of mtROS by H2 reduced the generation of oxidized mitochondrial DNA and consequently decreased its binding to NLRP3, thereby inhibiting the NLRP3 inflammasome activation. Our findings have, for the first time, revealed the novel mechanism underlying the inhibitory effect of molecular hydrogen on LPS-caused NLRP3 inflammasome activation, highlighting the promising application of this new antioxidant in the treatment of LPS-associated inflammatory pathological damage.

Zoledronic Acid may reduce intraoperative bleeding in spinal tumors: a prospective cohort study.

Between June 2010 and June 2011, 176 patients were divided into 2 groups: a group with spinal metastasis of solid tumors (n = 157) and a group with multiple myeloma (n = 19). Both groups were further divided into 2 subgroups: a group receiving zoledronic acid before surgery and a control group. The zoledronic acid subgroup of the solid tumors group was group A (n = 81), the control subgroup of the solid tumors group was group B (n = 76), the zoledronic acid subgroup of the multiple myeloma group was group C (n = 10), and the control subgroup of the multiple myeloma group was group D (n = 9). The average intraoperative blood loss during spinal surgery was as follows: 1311 ± 691 mL in group A and 1752 ± 740 mL in group B (P = 0.000) and 1994 ± 810 mL in group C and 3134 ± 795 mL in group D (P = 0.000). Patients receiving zoledronic acid before surgery had significantly less intraoperative bleeding than those who did not receive it. Preoperative use of zoledronic acid can effectively reduce intraoperative bleeding during surgery for the treatment of spinal tumors.

Glycyrrhizin suppresses the expressions of HMGB1 and relieves the severity of traumatic pancreatitis in rats.

BACKGROUND: High mobility group box 1 (HMGB1) plays important roles in a large variety of diseases; glycyrrhizin (GL) is recognized as an HMGB1 inhibitor. However, few studies have focused on whether glycyrrhizin can potentially improve the outcome of traumatic pancreatitis (TP) by inhibiting HMGB1. METHODS: A total of 60 male Wistar rats were randomly divided into three groups (n = 20 in each): Control group, TP group and TP-GL group. Pancreatic trauma was established with a custom-made biological impact machine-III, and GL was administered at 15 minutes after the accomplishment of operation. To determine survival rates during the first 7 days after injury, another 60 rats (n = 20 in each) were grouped and treated as mentioned above. At 24 hours of induction of TP, the histopathological changes in pancreas were evaluated and serum amylase levels were tested. Serum tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), and HMGB1 were measured using enzyme linked immunosorbent assay. HMGB1 expressions in pancreas were measured using immunohistochemical staining, Western blot and Real-Time PCR analysis. RESULTS: Serum levels of HMGB1, TNF-α and IL-6 were increased dramatically in TP group at 24 hours after induction of TP. However, these indicators were reduced significantly by GL administration in TP-GL group comparing with TP group (P < 0.05). Meanwhile, survival analysis showed that the seven-day survival rate in TP-GL group was significantly higher than that in TP group (85% versus 65%, P < 0.05). GL treatment significantly decreased the pancreatic protein and mRNA expressions of HMGB1 and ameliorated the pancreatic injury in rats with TP. CONCLUSIONS: Glycyrrhizin might play an important role in improving survival rates and ameliorating pancreatic injury of TP by suppression of the expressions of HMGB1 and other proinflammatory cytokine.

Pharmacological blockade of the MaxiK channel attenuates experimental acute pancreatitis and associated lung injury in rats.

Increasing evidence has recently demonstrated that soluble heparan sulfate (HS), a degradation product of extracellular matrix produced by elastase, plays a key role in the aggravation of acute pancreatitis (AP) and associated lung injury. However little is known about the detailed mechanism underlying HS-induced inflammatory cascade. Our previous work has provided a valuable clue that a large-conductance K(+) channel (MaxiK) was involved in the HS-stimulated activation of murine macrophages. Here we attempted to ask whether pharmacological inhibition of the MaxiK channel will exert beneficial effects on the treatment of AP and secondary lung injury. The protective effects of paxilline, a specific blocker of MaxiK, on rats against sodium taurocholate induced AP were evaluated. Our data showed that paxilline substantially attenuated AP and resultant lung injury, mainly by limiting the burst of inflammatory responses, as proven by decreased plasma concentrations of tumor necrosis factor-α and macrophage inflammatory protein-2, together with unimpaired pancreatic enzyme activities in rats suffering from AP. Compared with the therapeutic administration, pre-treatment of paxilline showed superior potential to slow down the progress of AP. Furthermore, AP rats received paxilline exhibited improved histopathologic alterations both in the pancreas and the lungs, and even lower lung MPO activity. Taken together, our study provides evidence that MaxiK is involved in the spread of inflammatory responses and the following lung injury during the attack of AP, indicating that this ion channel is a promising candidate as a therapeutic target for AP.

Involvement of a membrane potassium channel in heparan sulphate-induced activation of macrophages.

Increasing evidence has demonstrated that Toll-like receptor 4 (TLR4) -mediated systemic inflammatory response syndrome accompanied by multiple organ failure, is one of the most common causes of death in patients with severe acute pancreatitis. Recent reports have revealed that heparan sulphate (HS) proteoglycan, a component of extracellular matrices, potentiates the activation of intracellular pro-inflammatory responses via TLR4, contributing to the aggravation of acute pancreatitis. However, little is known about the participants in the HS/TLR4-mediated inflammatory cascades. Our previous work provided a clue that a membrane potassium channel (MaxiK) is responsible for HS-induced production of inflammatory cytokines. Therefore, in this report we attempted to reveal the roles of MaxiK in the activation of macrophages stimulated by HS. Our results showed that incubation of RAW264.7 cells with HS up-regulated MaxiK and TLR4 expression levels. HS could also activate MaxiK channels to promote the efflux of potassium ions from cells, as measured by the elevated activity of caspase-1, whereas this was significantly abolished by treatment with paxilline, a specific blocker of the MaxiK channel. Moreover, it was found that paxilline substantially inhibited HS-induced activation of several different transcription factors in macrophages, including nuclear factor-κB, p38 and interferon regulatory factor-3, followed by decreased production of tumour necrosis factor-α and interferon-ß. Taken together, our investigation provides evidence that the HS/TLR4-mediated intracellular inflammatory cascade depends on the activation of MaxiK, which may offer an important opportunity for a new approach in therapeutic strategies of severe acute pancreatitis.

Effects of treatment with hydrogen sulfide on methionine-choline deficient diet-induced non-alcoholic steatohepatitis in rats.

BACKGROUND AND AIM: Oxidative stress and inflammation play important roles in the progression from simple fatty liver to non-alcoholic steatohepatitis (NASH). The aim of this work was to investigate whether treatment with hydrogen sulfide (H2 S) prevented NASH in rats through abating oxidative stress and suppressing inflammation. METHODS: A methionine-choline-deficient (MCD) diet rat model was prepared. Rats were divided into three experimental groups and fed for 8 weeks as follows: (i) control rats; (ii) MCD-diet-fed rats; (iii) MCD-diet-fed rats treated with NaHS (intraperitoneal injection of 0.1 mL/kg/day of 0.28 mol/L NaHS, a donor of H2 S). RESULTS: MCD diet impaired hepatic H2 S biosynthesis in rats. Treatment with H2 S prevented MCD-diet-induced NASH, as evidenced by hematoxylin and eosin staining, reduced apoptosis and activities of alanine aminotransferase and aspartate aminotransferase, and attenuated hepatic fat accumulation in rats. Treatment with H2 S abated MCD-diet-induced oxidative stress through reducing cytochrome p4502E1 expression, enhancing heme oxygenase-1 expression, and suppressing mitochondrial reactive oxygen species formation, and suppressed MCD-diet-induced inflammation through suppressing activated nuclear factor κB signaling and reducing interleukin-6 and tumor necrosis factor α expressions. In addition, treatment of MCD-diet fed rats with H2 S had a beneficial modulation on expression profiles of fatty acid metabolism genes in livers. CONCLUSIONS: Treatment with H2 S prevented NASH induced by MCD diet in rats possibly through abating oxidative stress and suppressing inflammation.

[Protective effect of Ligustrazine preconditioning on hepatic energy metabolism in ischemia/reperfusion injury of rat].

OBJECTIVE: Objective to investigate the protective effects of Ligustrazine preconditioning against hepatic ischemia/reperfusion injury (IRI) in rats. METHODS: Fifty male Wistar rats were randomly allocated into 3 groups: sham operation group, in which animals underwent laparotomy, experimental group and control group in which were treated with 70% IRI of the liver, especially, the animals in experimental group was given intraperitoneal injection of 2 mL Ligustrazine per day for 3 days before operation. After the operation, liver tissues were harvested at 1 h, 6 h, 24 h and 72 h for the study of histomorphological change, the respiratory control ratio (RCR) and phosphorus: oxygen ratio (P/O) of hepatocytes mitochondria, and the contents of adenosine triphosphate (ATP) of liver tissue. RESULTS: (1) The damage hepatic tissue in experimental group was slighter than that in control group at each corresponding time-point after operation. (2) The RCR and P/O ratio at each corresponding time-point were higher in experimental group than those in control group (P < 0.05), and all of the two groups recovered after 72 h. (3) The ATP concentration in experimental group also was higher than that in control group at each corresponding time-point, and recovered faster than control group. CONCLUSION: The current results show that Ligustrazine preconditioning may improve energy metabolism of rat liver in ischemia reperfusion injury.

Hydrogen-rich saline reduces the oxidative stress and relieves the severity of trauma-induced acute pancreatitis in rats.

BACKGROUND: Currently, little evidence exists to support whether the therapeutic approaches for treating ordinary acute pancreatitis (AP) are effective in trauma-induced pancreatitis. Hydrogen-rich (H2) saline is an antioxidant treatment capable of ameliorating the severity of L-arginine-induced AP. In this study, we attempted to validate its protective role against traumatic pancreatitis (TP). METHODS: A previously established experimental rat model of TP was generated by controlled delivery of high pressure air impact. The protective effects of H2 saline against TP were evaluated in this model system by measuring survival rate and determining changes in histopathology, plasma enzymes, cytokines, and oxidative stress-associated molecules. RESULTS: Intraperitoneal administration of H2-rich saline produced a pronounced protection against TP in rats. Significant improvements were observed in survival rate and histopathological findings. In addition, plasma cytokines concentrations were reduced in H2 saline-treated TP rats. Although no marked inhibitory effect on plasma amylase and lipase activities was observed, H2 saline caused considerable suppression of pancreatic malondialdehyde level and recruitment of endogenous pancreatic antioxidants, such as glutathione and superoxide dismutase. CONCLUSIONS: H2-rich saline has beneficial effects on TP, presumably because of its detoxification activities against excessive reactive oxygen species. Our findings highlight the potential of H2-rich saline as a therapeutic agent of trauma-induced AP.

Cyclic Limulus anti-lipopolysaccharide (LPS) factor-derived peptide CLP-19 antagonizes LPS function by blocking binding to LPS binding protein.

Inflammation and septic shock due to endotoxins from Gram-negative bacteria infection continue to pose significant challenges to human healthcare. It is, therefore, necessary to develop therapeutic strategies targeting endotoxins, such as lipopolysaccharide (LPS), to prevent their potentially systemic effects. Pathogenesis due to Gram-negative bacteria involves LPS binding to the host LPS-binding protein (LBP), causing detrimental downstream signaling cascades. Our previous study showed that CLP-19, a synthetic peptide derived from the Limulus anti-LPS factor (LALF), could effectively neutralize LPS toxicity; however, the detailed mechanisms underlying this anti-LPS effect remained unexplained. Thus, we carried out investigations to determine how the CLP-19 neutralizes LPS toxicity. CLP-19 was found to block LPS binding to LBP in a dose-dependent manner, as evidenced by competitive enzyme-linked immunosorbent assay (ELISA). In peripheral blood mononuclear cells, CLP-19 blocked LPS-induced phosphorylation of mitogen activated protein kinase (MAPK) signaling proteins p38, extracellular signal-regulating kinase (ERK)1/2 and c-Jun N-terminal kinase (JNK)1/2. Furthermore, CLP-19 potency in LPS antagonism in vitro and in vivo was directly associated with its ability to block the LPS-LBP interaction. Taken together, the results suggested that CLP-19's inhibitory effect on LPS-LBP binding and on the subsequent MAPK pathway signaling may be responsible for its anti-LPS mechanism. This peptide appears to represent a potential therapeutic agent for clinical treatment of sepsis.

Management of patients with sphincter of Oddi dysfunction based on a new classification.

AIM: To propose a new classification system for sphincter of Oddi dysfunction (SOD) based on clinical data of patients. METHODS: The clinical data of 305 SOD patients documented over the past decade at our center were analyzed retrospectively, and typical cases were reported. RESULTS: The new classification with two more types (double-duct, biliary-pancreatic reflux) were set up on the basis of the Milwaukee criteria. There were 229 cases of biliary-type SOD, including 192 (83.8%) cases cured endoscopically, and 29 (12.7%) cured by open abdominal surgery, and the remaining 8 (3.5%) cases observed with unstable outcomes. Eight (50%) patients with pancreatic-type SOD were cured by endoscopic treatment, and the remaining 8 patients were cured after open abdominal surgery. There were 19 cases of double-duct-type SOD, which consisted of 7 (36.8%) patients who were cured endoscopically and 12 (63.2%) who were cured surgically. A total of 41 cases were diagnosed as biliary-pancreatic-reflux-type SOD. Twenty (48.8%) of them were treated endoscopically, 16 (39.0%) were treated by open abdominal surgery, and 5 (12.2%) were under observation. CONCLUSION: The newly proposed SOD classification system introduced in this study better explains the clinical symptoms of SOD from the anatomical perspective and can guide clinical treatment of this disease.

Experimental evidence supporting the lack of primary stem cells in adult pancreatic tissue.

PURPOSE: To investigate the origin and localization of pancreatic stem cells in adult pancreatic tissues and to determine the primary mechanism underlying the participation of these cells in repairing pancreatic injuries. METHODS: Sprague-Dawley rats were divided into experimental and control groups. The experimental group was given intraperitoneal injections of cerulein to induce acute pancreatitis. At 6 h, 1, 2, 3, 5 and 7 days, 5 rats from the experimental group and 2 rats from the control group were sacrificed; all sacrificed animals were intraperitoneally injected with 5-bromo-2'-deoxyuracil nucleotides (BrdU) 6 and 3 h prior to sacrifice. The pathological changes of pancreatic tissue were observed. The stem cell marker nestin and the cell proliferation marker BrdU were detected with immunohistochemistry. Pancreatic duodenal homeobox-1 (PDX-1) was determined by real-time PCR. RESULTS: (1) The pathological changes of acute pancreatitis can be divided into three phases: the edema and apoptosis phase, the hemorrhagic necrosis phase, and the reconstruction phase. (2) Nestin-positive cells mainly appeared in the interlobular vascular lumen after cerulein injection, and they peaked at day 3 when the positive cells spread all over the pancreatic tissues. (3) BrdU-positive cells began to appear in the area surrounding the interlobular region, and the number of positive cells peaked on day 7. (4) The expression of PDX-1 mRNA initially increased, then decreased and gradually got close to a normal level. CONCLUSION: Primary pancreatic stem cells may not exist in the adult pancreatic tissues. The so-called pancreatic stem cells may actually originate from bone marrow stem cells. When pancreatic tissue is injured, bone marrow stem cells may participate in the repair.

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.

[Study of in vitro endotoxin neutralization effect and antibacterial activity of limulus anti-lipopolysaccharide factor simulated peptide REMP2].

OBJECTIVE: To investigate the role of REMP2 derived from limulus anti-lipopolysaccharide factor in neutralizing endotoxin in vitro and its antibacterial activity. METHODS: (1) REMP2 and PMB in the concentrations of 100.00, 10.00, 1.00, 0.10, 0.01 micromol/L were respectively mixed with LPS (lEU/mL), with PMB as positive control. The LPS concentrations in different specimens were determined by routine method, and the neutralizing percentage was respectively calculated. (2) After adding isotonic saline (NS), the final concentrations of REMP2 and PMB were 10, 20, 40, 80 micromol/L, and the concentration of LPS was 100 microg/L. The murine monocytic macrophages were stimulated with LPS, then cultured with REMP2 and PMB, with NS in culture as negative control. The content of tumor necrosis factor (TNF)-alpha was determined by ELISA kit. (3) The morphologic changes of Escherichia coli. was observed under electron microscope at 10, 20 and 40 minutes after addition of REMP2 to Escherichia coli suspension (with terminal concentration of REMP2 at 40 micromol/L). RESULTS: There were no significant difference in endotoxin-neutralizing percentages between PMB and REMP2 in concentrations of 0.10, 10.00, 100.00 micromol/L (P > 0.05). The contents of TNF-alpha were 1175 +/- 162, 859 +/- 122, 645 +/- 142, 489 +/- 102 ng/L, respectively,after treatment of 10, 20, 40, 80 micromol/L REMP2, which were obviously lower than that of NS (3463 +/- 218 ng/L, P < 0.01). Under transmission electron microscope, the outer and interior membranes of Escherichia coli were obscure and rough, bacterial bodies were swollen with vacuoles in cytoplasm after treatment with REMP2. CONCLUSION: REMP2 has ability of neutralizing endotoxin and also antibacterial activity.

A synthetic cyclic peptide derived from Limulus anti-lipopolysaccharide factor neutralizes endotoxin in vitro and in vivo.

Endotoxin, also known as lipopolysaccharide (LPS), is the major mediator of septic shock due to Gram-negative bacterial infections. Recently, much attention has been focused on cationic peptides which possess the potential to detoxify LPS. Limulus anti-LPS factor (LALF), a protein found in the horseshoe crab (Limulus polyphemus), has been proved with striking anti-LPS effects. We synthesized a cyclic peptide (CLP-19), and then investigated its bioactivity both in vitro and in vivo. The ability of CLP-19 to neutralize LPS in vitro was tested using a Limulus amebocyte lysate (LAL) assay and the LPS-binding affinity was measured with an affinity biosensor method. The synthetic peptide LALF31-52 (residues 31 to 52 of LALF) was used as the positive control peptide in this study. It was found that CLP-19 exhibited the significant activity to antagonize LPS without observable cytotoxicity effect on mouse macrophages. CLP-19 directly bound to LPS, and neutralized it in a dose-dependent manner in the LAL assay. Moreover, CLP-19 also showed the remarkable ability to protect mice from lethal LPS attack and to inhibit the LPS-induced tumor necrosis factor alpha (TNF-alpha) release by decreasing serum LPS in vivo. Our work suggests that this peptide is worthy of further investigation as a potential anti-LPS agent in the treatment of septic shock.

[Reproduction of the murine endotoxin shock model in D-galactosamine-sensitized KunMing mice].

OBJECTIVE: To reproduce a Kunming murine endotoxin shock model suitable for the anti-endotoxin pharmaceutical research. METHODS: Kunming mice were challenged with an intraperitoneal (i. p.) injection of different doses of D-galactosamine (D-Gal) and endotoxin (LPS) and divided into 10 groups: i.e, group 1 [with injection of isotonic saline solution (NS) and LPS]; group 2 (with injection of NS and 90mg/kg LPS), group 3 (with injection of NS and 500mg/kg D-Gal), group 4 (with injection of 500mg/kgD-Gal and 25 microg /kg LPS), group 5 (with injection of 500mg/kg D-Gal and 50 microg/kg LPS), group 6(with injection of 500mg/kg D-Gal and 250 microg/kg LPS), group 7( with injection of NS and 600mg/ kg D-Gal), group 8 (with injection of 600mg/kg D-Gal and 10 microg/kg LPS), group 9( with injection of 600mg/kg D-Gal and 25 microg/kg LPS), group 10 (with injection of 600mg/kg D-Gal and 50 microg/kg LPS). The death of the mice were observed and the mortality rate was recorded at 48 post-injection hour (PIH). The dose of D-Gal and LPS which caused 100% lethality was chosen for the subsequent experiment to serve as control group (with injection of NS and 600mg/kg D-Gal), LPS group (with injection of 600mg/kg D-Gal and 580mg/kg LPS for later experiment). The venous blood of the mice were collected for the detection of serum content of TNF-alpha with ELISA method at 30, 75 and 120 post-injection minutes (PIM). The tissues of lung, liver, intestine were also harvested at 5 PIH for the pathological examination. RESULTS: The lethality of mice was 100% in the groups 2, 6 and 10 (P < 0.01). The serum content of TNF-alpha was maintained in a low level in control group, but it increased remarkably in LPS group, and it reached peak at 75 PIM (6365 +/- 2087ng/L, P < 0.01). Obvious inflammatory reaction was observed in the lung, liver and intestine in LPS group, while only mild inflammatory reaction was observed in liver in control group. CONCLUSION: The Kunming mice showed signs of endotoxin shock after D-galactosamine presensitizing and endotoxin challenge, and it is suitable for anti-endotoxin pharmaceutical research.