Phyto-therapeutic potential of stem bark of the wonder tree, Prosopis cineraria (L.) Druce in LPS-induced mouse model: An Anti-Inflammatory Study

Background

Therapeutic potential of Prosopis cineraria has been extensively explored by many eminent researchers against various serious diseases but its activity against Lipopolysaccharide (endotoxin) is obscure. Therefore, present experimental investigation was conducted to unravel and analyze the anti-inflammatory potential of hydro-ethanol extract of Prosopis cineraria against LPS-induced inflammation in Swiss albino male mice.

Methods

Swiss Albino male mice were intoxicated (intra-peritoneal) with LPS (2 mg/kg body weight) and further treated with low and high dose (i.e. 100 mg/kg body weight and 300 mg/kg body weight respectively) of hydro-ethanol extract of stem-bark of Prosopis cineraria. The levels of cytokines (TNF-α, Prostaglandins E2, IL-6, NF-κBp65, IFN-γ and IL-10) were determined in liver homogenate. Nitric oxide generated due to LPS-induced toxicity was estimated by using Griess reagent.

Results

The results demonstrated that the plant extract suppressed the over-expression and altered levels of cytokines due to LPS intoxication and restored the levels of TNF-α, NF-κB, NO, IL-6, IFN- γ, Prostaglandin E2 and IL-10.

Conclusion

The present research work unravelled the alleviating potential of Prosopis cineraria against LPS-induced inflammation by modulating the expression of cytokines.

Antibiotic-induced endotoxin release is organism-dependent in experimental Gram-negative sepsis

The majority of in vitro and animal experiments that have been performed to assess antibiotic-induced endotoxin release (AIER) have employed a single test isolate, usually Escherichia coli. To determine the influence of microorganism type on AIER and interleukin-6 (IL-6) response, CF-1 mice were made septic following a 12-15% total body surface area nonlethal burn and subeschar challenge (LD90) with Klebsiella pneumoniae K2 (∼103 cfu), Proteus mirabilis 4552 (∼101 cfu) and Pseudomonas aeruginosa SBI-N (∼102 cfu). Three intraperitoneal (i.p.) doses, given every 4 h, of ceftazidime (TAZ, 200 mg/kg), imipenem (IMI, 100 mg/kg), ciprofloxacin (CIP, 25 mg/kg) and gentamicin (GEN, 25 mg/kg) were administered post burn and infection beginning when mice were septic with organ dysfunction. Free endotoxin concentrations were significantly ( P < 0.001) higher following all antibiotics for treatment of K. pneumoniae as compared to Ps. aeruginosa (intermediate) and P. mirabilis infections. Differential AIER was highest for TAZ and IMI, intermediate for CIP and lowest for GEN, for the treatment of K. pneumoniae and Ps. aeruginosa infections. There was a strong positive correlation between endotoxin release and IL-6 production for K. pneumoniae-treated animals, however increased endotoxin levels for Pseudomonas were accompanied by decreases in IL-6 levels. For P. mirabilis infection endotoxin levels were comparatively low, but highest for GEN and IMI. However, corresponding IL-6 levels increased only 3.2-fold for IMI and actually decreased by 50% for GEN following the first dose. Interestingly, CIP resulted in only modest endotoxin release and TAZ caused no appreciable release, however IL-6 concentrations dramatically increased 39.9-fold (TAZ) and 32.6-fold (CIP). This suggests that other pro-inflammatory mediators released from the bacterium, and not endotoxin, were more important determinants in the overall host response to antibiotic exposure. In conclusion, these data provide supportive evidence that absolute and differential AIER and production of IL-6 is organism-dependent in experimental Gram-negative sepsis. As a result, general conclusions concerning differential AIER for infection caused by E. coli or K. pneumoniae cannot necessarily be extrapolated to other species of Gram-negative bacilli. Furthermore, these study results strongly indicate that the microorganism and other pertinent pro-inflammatory factors (i.e. exotoxins, proteases), must be taken into account in the study design and data analysis of any experimental or clinical trial that is conducted to determine the significance of differential AIER.

Therapeutic efficacy of mammary irrigation regimen in dairy cattle diagnosed with acute coliform mastitis

The objective of this field study was to determine the therapeutic efficacy of mammary irrigation for the treatment of dairy cattle diagnosed with acute coliform mastitis caused by gram-negative bacteria. Additionally, the effects of different mammary irrigation regimen fluids such as ozone water and normal saline were compared. Dairy cattle clinically diagnosed with acute coliform mastitis (n = 57) were enrolled in the study, randomly assigned to 1 of 3 groups, and received the following treatments: systemic antibiotic administration (SAA group; n = 40), mammary irrigation regimen (MIR group; n = 10), and both treatments (MIX group; n=7). Significant antipyretic effects, as assessed by rectal temperature measurement, were observed in the MIX and MIR groups. Although 2 irrigating fluids were used, namely, ozone water and normal saline, no significant difference was observed between the 2 groups. Fourteen days after the onset of the treatments, the milk yield recovery rate in MIR group tended to be higher (p = 0.06) than that in the SAA group. Additionally, after 30 days of treatment, the MIR group cows demonstrated significantly higher successful recovery rates (p<0.05) than the SAA group cows. These results indicate that mammary irrigation with normal saline is an effective treatment for acute coliform mastitis in dairy cattle.

Comparison of the amounts of endotoxin released from Escherichia coli after exposure to antibiotics and ozone: an in vitro evaluation

Antibiotic therapy administered for treatment of gram-negative bacterial infections can exert a negative effect in the form of endotoxin shock. Therefore, a sterilization method that releases little endotoxin is required. This in vitro study aimed to compare the amounts of endotoxin released from Escherichia coli exposed to antibiotics (aminobenzylpenicillin, kanamycin, oxytetracycline, sulfadimethoxine and enrofloxacin) or ozone. The bacterial growth and amount of endotoxin released were measured at specific time points. Compared with antibiotic treatment, ozone sterilization induced release of smaller amounts of endotoxin from the bacteria. Moreover, no major differences were observed when ozone was used against the purified endotoxin. We conclude that compared with antibiotic treatment, ozone sterilization may release smaller amounts of endotoxin.

Effect of antibiotics on polymorphonuclear neutrophil apoptosis

STUDY OBJECTIVE

To evaluate the effects of various antibiotics-direct and indirect as a result of bacterial killing-on polymorphonuclear neutrophil (PMN) apoptosis.

DESIGN

In vitro analysis.

SETTING

Research laboratory.

INTERVENTION

Whole blood collected from healthy human subjects was incubated with and without Klebsiella pneumoniae (1.0 x 10(5) colony-forming units [cfu]/ml) plus ceftazidime 50 microg/ml, gentamicin, ciprofloxacin, trovafloxacin, tetracycline, doxycycline, erythromycin, azithromycin (each 5 microg/ml), or lipopolysaccharide 10 microg/ml. After staining with fluorescein-conjugated annexin V, red blood cells were lysed, and the remaining white blood cells were assessed by flow cytometry with gating on PMNs.

MEASUREMENTS AND MAIN RESULTS

In the absence of K. pneumoniae infection, antibiotic exposure directly decreased PMN apoptosis by 17.8% (range -25.0% to -13.9%, p=0.008) compared with untreated cells. In the presence of K. pneumoniae, all antibiotic treatments, even those with poor in vitro activity for the bacterial isolate, decreased PMN apoptosis by 26.2% (range -38.0% to -17.8%, p<0.001) compared with untreated control cells and by 36.6% compared with untreated (no antibiotic) K. pneumoniae-stimulated cells (range -46.2% to -28.0%, p<0.001).

CONCLUSIONS

All tested antibiotics in clinically relevant concentrations resulted in modest yet consistent decreases in PMN apoptosis. The magnitude of this change increased slightly in the presence of K. pneumoniae infection. In vivo studies are needed to determine whether antibiotic-associated prolongation of PMN survival improves host response to infection.

High therapeutic index of factor C Sushi peptides: potent antimicrobials against Pseudomonas aeruginosa

Factor C protein isolated from the horseshoe crab, Carcinoscorpius rotundicauda, has endotoxin binding capability. Synthetic peptides of 34 amino acids based on the sequence of two regions of factor C (Sushi 1 and Sushi 3) as well as their corresponding mutants exhibited activities against 30 clinical isolates of Pseudomonas aeruginosa. Collectively, all four peptides demonstrated exceptionally effective bactericidal activity against P. aeruginosa with 90% minimal bactericidal concentrations (MBC(90)s) in the range of 0.06 to 0.25 microg/ml (16 to 63 nM). Viable bacteria were reduced by 90% after 7 min and were totally eradicated within 40 to 50 min. These peptides are minimally hemolytic against both rabbit and human erythrocytes even at concentrations up to 1,600-fold their MBC(90)s. Both in vitro and in vivo studies indicate that cytotoxic effects are small even at 1,000-fold their MBC(90)s. Furthermore, the Sushi peptides are tolerant of high-salt and adverse pH conditions. These findings demonstrate the promising therapeutic potential of the Sushi peptides.

Morphological change in Pseudomonas aeruginosa following antibiotic treatment of experimental infection in mice and its relation to susceptibility to phagocytosis and to release of endotoxin

The relationship between morphological changes in Pseudomonas aeruginosa following antibiotic treatment of experimental infection in mice, susceptibility to phagocytosis, and release of endotoxin was studied. The intraperitoneal administration of P. aeruginosa with imipenem or ceftazidime into mice induced morphological changes in the cells 2 h after injection. Round P. aeruginosa cells with imipenem treatment became susceptible to phagocytosis by peritoneal cells, whereas long filamentous cells with ceftazidime treatment were hardly phagocytized by peritoneal cells. The morphological changes also affected the plasma endotoxin level in the circulation.

Biological characterization of endotoxins released from antibiotic-treated Pseudomonas aeruginosa and Escherichia coli

The supernatants taken from Pseudomonas aeruginosa and Escherichia coli cultures in human sera or chemically defined M9 medium in the presence of ceftazidime (CAZ) contained high levels of endotoxin, while those taken from the same cultures in the presence of imipenem (IPM) yielded a very low level of endotoxin. The biological activities of endotoxin in the supernatants were compared with those of phenol water-extracted lipopolysaccharide (LPS). The endotoxin released from the organisms as a result of CAZ treatment (CAZ-released endotoxin) contained a large amount of protein. The protein, however, lacked endotoxic activity, since the endotoxin did not show any in vivo toxic effects in LPS-hyporesponsive C3H/HeJ mice sensitized with D-(+)-galactosamine (GalN) or any activation of C3H/HeJ mouse macrophages in vitro. The activities of CAZ- and IPM-released endotoxin (as assessed by a chromogenic Limulus test) were fundamentally the same as those of P. aeruginosa LPS, since their regression lines were parallel. The CAZ-released endotoxin was similar to purified LPS with respect to the following biological activities in LPS-responsive C3H/HeN mice and LPS-hyporesponsive C3H/HeJ mice: lethal toxicity in GalN-sensitized mice, in vitro induction of tumor necrosis factor- and NO production by macrophages, and mitogen-activated protein kinase activation in macrophages. The macrophage activation by CAZ-released endotoxin as well as LPS was mainly dependent on the presence of serum factor and CD14 antigen. Polymyxin B blocked the activity. These findings indicate that the endotoxic activity of CAZ-released endotoxin is due primarily to LPS (lipid A).

Effect of O-antigenic polysaccharide of Escherichia coli on endotoxin neutralizing activity of lysozyme

Endotoxemia is considered to be associated with the high mortality of gram-negative septic patients. Increasing evidence shows that beta-lactam antibiotics have a propensity to induce endotoxin release from the bacterial outer membrane while killing bacteria. We have recently found that egg white lysozyme (EW-LZM) shows strong inhibition of beta-lactam induced bacteriolysis and lipopolysaccharide (LPS) release from Escherichia coli O111, resulting in reduction of the LPS-initiated inflammatory response. In this study, we compared the effect of EW-LZM on E. coli J5, which possesses rough-type LPS (RaLPS), in order to demonstrate the effect of O-antigenic polysaccharide on endotoxin neutralizing activity of EW-LZM and on inhibition of beta-lactam induced lysis by LZM. Both of the beta-lactam induced bacterial lysis and subsequent LPS release were almost completely inhibited by EW-LZM. The effect was more potent than that of wild-type LPS as assessed by released LPS concentration and LPS induced cytokine syntheses. In addition, EW-LZM was effective against lethal infection of E. coli J5 in cyclophosphamide induced leukopenic mice. These facts strongly suggested that O-antigenic polysaccharide negatively modulates LPS neutralizing activity of EW-LZM.

Endotoxin removal with poly(ethyleneimine)-immobilized adsorbers: Sepharose 4B versus flat sheet and hollow fibre membranes

Poly(ethyleneimine) was immobilized on poly(vinyl alcohol)-coated nylon flat sheet membranes, poly(vinyl alcohol) and poly(ethylenevinyl alcohol) hollow fibre membranes as well as Sepharose 4B. The resulting poly(ethyleneimine)-immobilized adsorbers were used for removal of E. coli derived endotoxin from buffers and bovine serum albumin solutions. The efficiency of poly(ethyleneimine) proved to be constant over a wide pH range, including phosphate buffered saline. The performance depended upon the matrix type employed: endotoxin clearance factors varied from 100 to 120,000 in protein-free solutions and 40 to 33,000 in solutions of bovine serum albumin using 6000 EU/ml as feed concentration. The best adsorber was the flat sheet membrane-immobilized poly(ethyleneimine), followed by the hollow fibre-immobilized poly(ethyleneimine) and poly(ethyleneimine)-Sepharose. The factors influencing endotoxin clearance were the mass transport (convective systems were superior to the diffusive system), the chemical composition and the surface structure of the underlying matrix.

Antibacterial and anti-inflammatory agents that target endotoxin

Antibiotic-resistant bacterial infections are a major clinical problem. Lipid A, the active part of lipopolysaccharide endotoxins in Gram-negative bacteria, is an intriguing target for new antibacterial and anti-inflammatory agents. Inhibition of lipid A biosynthesis kills most Gram-negative bacteria, increases bacterial permeability to antibiotics and decreases endotoxin production.

The significance of endotoxin release in experimental and clinical sepsis in surgical patients--evidence for antibiotic-induced endotoxin release?

Sepsis and peritonitis remain a serious challenge for surgical patients, despite improvement in surgical therapy and intensive care and the introduction of new powerful antibiotics. Recent in vitro studies revealed the potential of certain antibiotics, e.g. penicillin-binding protein (PBP) 3-specific antibiotics, to cause antibiotic-induced endotoxin release. Other types of antibiotics, e.g., PBP 2-specific antibiotics, were associated with no or less endotoxin release. Further in vitro experiments and investigations in animals support the hypothesis of antibiotic-induced endotoxin release, but there is little clinical evidence. The clinical significance of endotoxin is subject of open dispute with many pro's and contra's. Endotoxin, although an important trigger, may not be the only factor to induce cytokine release, e.g., peptidoglycans were able to stimulate cells to release cytokines. Gram-positive pathogens have gained more importance in clinical sepsis and may not be sufficiently reflected in current clinical studies. The hypothesis that neutralization of endotoxin and pro-inflammatory cytokines is beneficial in sepsis was seriously challenged by the results of recent clinical and experimental studies. The better understanding of mechanisms in endotoxin-induced cell activation and cell, cell-receptor and soluble receptor interactions led to new treatment options. Recent reports on the complex pathogenesis of peritonitis and the detection of pathogen-related factors with intraperitoneal immune response may have implications on clinical studies investigating the potential of new compounds and the effect of antibiotics on endotoxin release. However, only few reports are available on the clinical significance of antibiotic-induced endotoxin release, and association of endotoxin release with pathogens, mortality or alteration of physiological parameters were not observed. With regard to the particulars of these studies, e.g., a small study population or low mortality rate, mortality may not be an ideal outcome parameter for these studies. There is clinical evidence for antibiotic-induced endotoxin release. However, the need for well-designed and performed studies using newly developed monitoring devices in intensive care therapy is obvious.