scholarly journals Bactericidal and Antiendotoxic Properties of Short Cationic Peptides Derived from a Snake Venom Lys49 Phospholipase A2

2005 ◽  
Vol 49 (4) ◽  
pp. 1340-1345 ◽  
Author(s):  
Carlos Santamaría ◽  
Silda Larios ◽  
Steve Quirós ◽  
Javier Pizarro-Cerda ◽  
Jean-Pierre Gorvel ◽  
...  
Keyword(s):  
Bactericidal Activity ◽  
Aromatic Amino Acids ◽  
Polymyxin B ◽  
Phospholipase A ◽  
Necrosis Factor Alpha ◽  
Parent Protein ◽  
Serovar Typhimurium ◽  
Microbial Infections ◽  
Intraperitoneal Infection

ABSTRACT The activities of short synthetic, nonhemolytic peptides derived from the C-terminal region of myotoxin II, a catalytically inactive phospholipase A2 homologue present in the venom of the snake Bothrops asper, have been shown to reproduce the bactericidal activity of the parent protein. They combine cationic and hydrophobic-aromatic amino acids, thus functionally resembling the antimicrobial peptides of innate defenses. This study evaluated the antimicrobial and antiendotoxic properties of a 13-mer derivative peptide of the C-terminal sequence from positions 115 to 129 of myotoxin II, named pEM-2. This peptide (KKWRWWLKALAKK) showed bactericidal activity against both gram-positive and gram-negative bacteria. In comparison to previously described peptide variants derived from myotoxin II, the toxicity of pEM-2 toward eukaryotic cells in culture was significantly reduced, being similar to that of lactoferricin B but lower than that of polymyxin B. The all-d enantiomer of pEM-2 [pEM-2 (d)] retained the same bactericidal potency of its l-enantiomeric counterpart, but it showed an enhanced ability to counteract the lethal activity of an intraperitoneal lipopolysaccharide challenge in mice, which correlated with a significant reduction of the serum tumor necrosis factor alpha levels triggered by this endotoxin. Lethality induced by intraperitoneal infection of mice with Escherichia coli or Salmonella enterica serovar Typhimurium was reduced by the administration of pEM-2 (d). These results demonstrate that phospholipase A2-derived peptides may have the potential to counteract microbial infections and encourage further evaluations of their actions in vivo.

scholarly journals Host Immune Response to Salmonella enterica Serovar Typhimurium Infection in Mice Derived from Wild Strains

2002 ◽  
Vol 70 (4) ◽  
pp. 1997-2009 ◽  
Author(s):  
Giovanna Sebastiani ◽  
Véronique Blais ◽  
Vanessa Sancho ◽  
Stefanie N. Vogel ◽  
Mary M. Stevenson ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Disease Manifestation ◽  
Necrosis Factor Alpha ◽  
Gram Negative ◽  
Nitrite Production ◽  
Serovar Typhimurium ◽  
Wild Strains ◽  
Interleukin 1Α

ABSTRACT Studies of mouse models of endotoxemia and sepsis with gram-negative bacteria have shown that the host response is genetically controlled. Mice infected with the gram-negative bacterium Salmonella enterica serovar Typhimurium exhibit marked genetic differences in disease manifestation, and the wild-derived strain Mus musculus molossinus MOLF/Ei is extremely susceptible to S. enterica serovar Typhimurium. The kinetics of bacterial proliferation within the liver and the spleen and histological examination of tissue sections have suggested that MOLF/Ei mice do not succumb to infection because of overwhelming bacterial growth in the reticuloendothelial organs or massive tissue necrosis, as observed in other Salmonella-susceptible strains. MOLF/Ei mice respond normally to lipopolysaccharide (LPS) in vivo and in vitro, as determined by the production of tumor necrosis factor alpha and spleen cell mitogenesis. However, they have a unique cytokine profile in response to infection compared to that observed for other Salmonella-susceptible mice. There was increased expression of mRNA of the interleukin-1α (IL-1α) and IL-1β genes as the infection in the spleens and livers of MOLF/Ei mice progressed. Despite the fact that MOLF/Ei mice have the ability to respond to LPS and the fact that there are significant increases in IL-1α and IL-1β mRNA, Nos2 in the spleen is not upregulated and nitrite production by spleen cells is reduced. At the central level, the inflammatory response is characterized by strong upregulation of the inhibitory factor kappa B alpha and Toll-like receptor 2 genes, two genes known to be regulated by LPS and IL-1 in the brain. The high levels of IL-1 expression in the spleens and livers of MOLF/Ei mice may have important implications for the activation of peripheral and central innate immune mechanisms.

scholarly journals Influence of Gastric Acid on Susceptibility to Infection with Ingested Bacterial Pathogens

2007 ◽  
Vol 76 (2) ◽  
pp. 639-645 ◽  
Author(s):  
Sharon M. Tennant ◽  
Elizabeth L. Hartland ◽  
Tongted Phumoonna ◽  
Dena Lyras ◽  
Julian I. Rood ◽  
...  
Keyword(s):  
Gastric Acid ◽  
Bacterial Pathogens ◽  
Susceptibility To Infection ◽  
Stomach Acid ◽  
Serovar Typhimurium ◽  
Increased Sensitivity ◽  
Intraperitoneal Infection ◽  
Resistance To Infection

ABSTRACT Despite the widely held belief that gastric acid serves as a barrier to bacterial pathogens, there are almost no experimental data to support this hypothesis. We have developed a mouse model to quantify the effectiveness of gastric acid in mediating resistance to infection with ingested bacteria. Mice that were constitutively hypochlorhydric due to a mutation in a gastric H+/K+-ATPase (proton pump) gene were infected with Yersinia enterocolitica, Salmonella enterica serovar Typhimurium, Citrobacter rodentium, or Clostridium perfringens cells or spores. Significantly greater numbers of Yersinia, Salmonella, and Citrobacter cells (P ≤ 0.006) and Clostridium spores (P = 0.02) survived in hypochlorhydric mice, resulting in reduced median infectious doses. Experiments involving intraperitoneal infection or infection of mice treated with antacids indicated that the increased sensitivity of hypochlorhydric mice to infection was entirely due to the absence of stomach acid. Apart from establishing the role of gastric acid in nonspecific immunity to ingested bacterial pathogens, our model provides an excellent system with which to investigate the effects of hypochlorhydria on susceptibility to infection and to evaluate the in vivo susceptibility to gastric acid of orally administered therapies, such as vaccines and probiotics.

scholarly journals Increased Ferroportin-1 Expression and Rapid Splenic Iron Loss Occur with Anemia Caused by Salmonella enterica Serovar Typhimurium Infection in Mice

2015 ◽  
Vol 83 (6) ◽  
pp. 2290-2299 ◽  
Author(s):  
Diane E. Brown ◽  
Heidi J. Nick ◽  
Melissa W. McCoy ◽  
Sarah M. Moreland ◽  
Aaron M. Stepanek ◽  
...  
Keyword(s):  
Inflammatory Disease ◽  
Salmonella Enterica ◽  
High Serum ◽  
Interleukin 12 ◽  
Necrosis Factor Alpha ◽  
Iron Sequestration ◽  
Ferroportin 1 ◽  
Systemic Inflammatory Disease ◽  
Serovar Typhimurium

The Gram-negative intracellular bacteriumSalmonella entericaserovar Typhimurium causes persistent systemic inflammatory disease in immunocompetent mice. Following oral inoculation withS. Typhimurium, mice develop a hematopathological syndrome akin to typhoid fever with splenomegaly, microcytic anemia, extramedullary erythropoiesis, and increased hemophagocytic macrophages in the bone marrow, liver, and spleen. Additionally, there is marked loss of iron from the spleen, an unanticipated result, given the iron sequestration reported in anemia of inflammatory disease. To establish why tissue iron does not accumulate, we evaluated multiple measures of pathology for 4 weeks following oral infection in mice. We demonstrate a quantitative decrease in splenic iron following infection despite increased numbers of splenic phagocytes. Infected mice have increased duodenal expression of the iron exporter ferroportin-1, consistent with increased uptake of dietary iron. Liver and splenic macrophages also express high levels of ferroportin-1. These observations indicate that splenic and hepatic macrophages export iron duringS. Typhimurium infection, in contrast to macrophage iron sequestration observed in anemia of inflammatory disease. Tissue macrophage export of iron occurs concurrent with high serum concentrations of interferon gamma (IFN-γ) and interleukin 12 (IL-12). In individual mice, high concentrations of both proinflammatory (tumor necrosis factor alpha [TNF-α]) and anti-inflammatory (IL-10) cytokines in serum correlate with increased tissue bacterial loads throughout 4 weeks of infection. Thesein vivoobservations are consistent with previous cell culture studies and suggest that the relocation of iron from tissue macrophages during infection may contribute to anemia and also to host survival of acuteS. Typhimurium infection.

scholarly journals Selection of Small-Colony Variants of Salmonella enterica Serovar Typhimurium in Nonphagocytic Eucaryotic Cells

2003 ◽  
Vol 71 (7) ◽  
pp. 3690-3698 ◽  
Author(s):  
David A. Cano ◽  
M. Graciela Pucciarelli ◽  
Marina Martínez-Moya ◽  
Josep Casadesús ◽  
Francisco García-del Portillo
Keyword(s):  
Salmonella Enterica ◽  
Aminolevulinic Acid ◽  
Aromatic Amino Acids ◽  
Phagocytic Cells ◽  
Phenotypic Analysis ◽  
Small Colony Variants ◽  
Enteropathogenic Bacteria ◽  
Serovar Typhimurium ◽  
Small Colony

ABSTRACT Salmonella enterica strains are enteropathogenic bacteria that survive and proliferate within vacuolar compartments of epithelial and phagocytic cells. Recently, it has been reported that fibroblast cells are capable of restricting S. enterica serovar Typhimurium intracellular growth. Here, we show that prolonged residence of bacteria in the intracellular environment of fibroblasts results in the appearance of genetically stable small-colony variants (SCV). A total of 103 SCV isolates, obtained from four independent infections, were subjected to phenotypic analysis. The following phenotypes were observed: (i) δ-aminolevulinic acid auxotrophy; (ii) requirement for acetate or succinate for growth in glucose minimal medium; (iii) auxotrophy for aromatic amino acids; and (iv) reduced growth rate under aerobic conditions not linked to nutrient auxotrophy. The exact mutations responsible for the SCV phenotype in three representative isolates were mapped in the lpd, hemL, and aroD genes, which code for dihydrolipoamide dehydrogenase, glutamate-1-semyaldehyde aminotransferase, and 3-dehydroquinate dehydratase, respectively. The lpd, hemL, and aroD mutants had intracellular persistence rates in fibroblasts that were 3 to 4 logs higher than that of the parental strain and decreased susceptibility to aminoglycoside antibiotics. All three of these SCV isolates were attenuated in the BALB/c murine typhoid model. Complementation with lpd+ , hem+ , and aroD+ genes restored the levels of intracellular persistence and antibiotic susceptibility to levels of the wild-type strain. However, virulence was not exhibited by any of the complemented strains. Altogether, our data demonstrate that similar to what it has been reported for SCV isolates of other pathogens, S. enterica SCV display enhanced intracellular persistence in eucaryotic cells and are impaired in the ability to cause overt disease. In addition, they also suggest that S. enterica SCV may be favored in vivo.

scholarly journals Identification and Genetic Characterization of PmrA-Regulated Genes and Genes Involved in Polymyxin B Resistance in Salmonella enterica Serovar Typhimurium

2002 ◽  
Vol 70 (12) ◽  
pp. 6770-6778 ◽  
Author(s):  
Rita Tamayo ◽  
Sara S. Ryan ◽  
Andrea J. McCoy ◽  
John S. Gunn
Keyword(s):  
Salmonella Enterica ◽  
Lipid A ◽  
Regulatory System ◽  
Enteric Bacteria ◽  
Polymyxin B ◽  
High Iron ◽  
Transposon Insertion ◽  
Mucosal Surfaces ◽  
Serovar Typhimurium

ABSTRACT Salmonella enterica serovar Typhimurium encounters antimicrobial peptides (AP) within the phagosomes of professional phagocytes and at intestinal mucosal surfaces. Salmonella serovar Typhimurium utilizes the two-component regulatory system PmrA-PmrB, which is activated in response to the environmental conditions encountered in vivo, to regulate resistance to several AP, including polymyxin B (PM). Random MudJ transposon mutagenesis was used to identify PmrA-PmrB-regulated genes, as well as genetic loci necessary for PM resistance. Three different phenotypic classes of genes were identified: those necessary for PM resistance and regulated by PmrA, those necessary for PM resistance and not regulated by PmrA, and PmrA-regulated genes not required for PM resistance. Loci identified as necessary for PM resistance showed between 6- and 192-fold increased sensitivities to PM, and transposon insertion sites include surA, tolB, and gnd. PmrA-regulated loci identified included dgoA and yibD and demonstrated 500- and 2,500-fold activation by PmrA, respectively. The role of the identified loci in aminoarabinose modification of lipid A was determined by paper chromatography. The gnd mutant demonstrated a loss of aminoarabinose from lipid A, which was suggested to be due to a polar effect on the downstream gene pmrE. The remaining PMs mutants (surA and tolB), as well as the two PmrA-regulated gene (yibD and dgoA) mutants, retained aminoarabinose on lipid A. yibD, dgoA, and gnd (likely affecting pmrE) played no role in PmrA-regulated resistance to high iron concentrations, while surA and tolB mutations grew poorly on high iron media. All PMs mutants identified in this study demonstrated a defect in virulence compared to wild-type Salmonella serovar Typhimurium when administered orally to mice, while the PmrA-regulated gene (yibD and dgoA) mutants showed normal virulence in mice. These data broaden our understanding of in vivo gene regulation, lipopolysaccharide modification, and mechanisms of resistance to AP in enteric bacteria.

scholarly journals Design of Glycoconjugate Vaccines against Invasive African Salmonella enterica Serovar Typhimurium

2014 ◽  
Vol 83 (3) ◽  
pp. 996-1007 ◽  
Author(s):  
S. Rondini ◽  
F. Micoli ◽  
L. Lanzilao ◽  
M. Gavini ◽  
R. Alfini ◽  
...  
Keyword(s):  
Bactericidal Activity ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Invasive Disease ◽  
Careful Consideration ◽  
Effective Vaccine ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Glycoconjugate Vaccines

Nontyphoidal salmonellae, particularlySalmonella entericaserovar Typhimurium, are a major cause of invasive disease in Africa, affecting mainly young children and HIV-infected individuals. Glycoconjugate vaccines provide a safe and reliable strategy against invasive polysaccharide-encapsulated pathogens, and lipopolysaccharide (LPS) is a target of protective immune responses. With the aim of designing an effective vaccine againstS. Typhimurium, we have synthesized different glycoconjugates, by linking O-antigen and core sugars (OAg) of LPS to the nontoxic mutant of diphtheria toxin (CRM197). The OAg-CRM197conjugates varied in (i) OAg source, with threeS. Typhimurium strains used for OAg extraction, producing OAg with differences in structural specificities, (ii) OAg chain length, and (iii) OAg/CRM197ratio. All glycoconjugates were compared for immunogenicity and ability to induce serum bactericidal activity in mice.In vivoenhancement of bacterial clearance was assessed for a selectedS. Typhimurium glycoconjugate by challenge with liveSalmonella. We found that the largest anti-OAg antibody responses were elicited by (i) vaccines synthesized from OAg with the highest glucosylation levels, (ii) OAg composed of mixed- or medium-molecular-weight populations, and (iii) a lower OAg/CRM197ratio. In addition, we found that bactericidal activity can be influenced byS. Typhimurium OAg strain, most likely as a result of differences in OAg O-acetylation and glucosylation. Finally, we confirmed that mice immunized with the selected OAg-conjugate were protected againstS. Typhimurium colonization of the spleen and liver. In conclusion, our findings indicate that differences in the design of OAg-based glycoconjugate vaccines against invasive AfricanS. Typhimurium can have profound effects on immunogenicity and therefore optimal vaccine design requires careful consideration.

Role of endotoxin in grain dust-induced lung inflammation in mice

1996 ◽  
Vol 270 (6) ◽  
pp. L1052-L1059 ◽  
Author(s):  
P. J. Jagielo ◽  
P. S. Thorne ◽  
J. A. Kern ◽  
T. J. Quinn ◽  
D. A. Schwartz
Keyword(s):  
Inflammatory Response ◽  
Membrane Filtration ◽  
Polymyxin B ◽  
Tnf Alpha ◽  
Necrosis Factor Alpha ◽  
Endotoxin Activity ◽  
Grain Dust

To investigate the role of endotoxin in grain dust-induced airway inflammation, we reduced the endotoxin activity from extracts of corn dust (CDE), using three distinct methods, and determined the effect of endotoxin activity on the in vitro and in vivo inflammatory response to CDE. Escherichia coli lipopolysaccharide solution (LPS) and CDE solution were separated into > 100-kDa and < 100-kDa fractions by ultracentrifugation. Endotoxin activity was predominantly present in the > 100-kDa fractions of the LPS and CDE solutions. Charged-membrane filtration of the > 100-kDa fractions of LPS and CDE resulted in the reduction of endotoxin activity by 99.9 and 80%, respectively. Treatment of the > 100-kDa fractions of LPS and CDE with polymyxin B-coated beads reduced the endotoxin activity by 96 and 89%, respectively. The untreated > 100-kDa fractions of LPS and CDE caused significantly greater (P < 0.01) release of tumor necrosis factor-alpha (TNF-alpha) from THP-1 cells in vitro compared with its respective < 100-kDa fraction or either of the treated (charged filter or polymyxin B) > 100-kDa fractions. Similarly, mice exposed to either of the untreated > 100-kDa fractions of LPS or CDE by inhalation developed significantly greater (P < 0.01) concentrations of lavage neutrophils and TNF-alpha in the lavage fluid compared with mice exposed to the respective < 100-kDa fraction or either of the treated > 100-kDa fractions. These results indicate that endotoxin is primarily responsible for the in vitro and in vivo inflammatory response to CDE.

scholarly journals Anti-inflammatory, Anti-bacterial and Anti-acetylcholinesterase Activities of two Isoquinoline Alkaloids–Scoulerine and Cheilanthifoline

2016 ◽  
Vol 11 (12) ◽  
pp. 1934578X1601101
Author(s):  
Phurpa Wangchuk ◽  
Thanapat Sastraruji ◽  
Malai Taweechotipatr ◽  
Paul A Keller ◽  
Stephen G Pyne
Keyword(s):  
Animal Studies ◽  
Antibacterial Activities ◽  
Isoquinoline Alkaloids ◽  
Necrosis Factor Alpha ◽  
Reference Drug ◽  
Tnf Α ◽  
Microbial Infections ◽  
Factor Alpha ◽  
Necrosis Factor

Corydalis plants containing isoquinoline alkaloids are reported to possess promising pharmacological properties for the treatment of important diseases including cancer, inflammation, Alzheimer's disease and microbial infections. As part of a wider program investigating Bhutanese medicinal plants, we have previously identified eight isoquinoline alkaloids from C. dubia. Out of these, we report here on two of the major alkaloids, scoulerine (1) and cheilanthifoline (2) and their inhibitory activities against acetylcholinesterase (anti-AChE), tumor necrosis factor alpha (anti TNF-α) and a bacterial strain, Helicobacter pylori. Both alkaloids showed weak anti TNF-α and antibacterial activities. However, the anti-AChE activity of scoulerine (1) was promising as it significantly inhibited AChE with a minimum inhibitory requirement (MIR) value of 0.0015 nmol, which was two-fold better than the reference drug, galanthamine (MIR value of 0.003 nmol). As there are limited anti-Alzheimer's chemotherapeutics, scoulerine (1) is worthy of further exploration, including lead optimization, structure-activity-relationship studies, analog development, pharmacodynamics and in vivo animal studies

scholarly journals Identification of cptA, a PmrA-Regulated Locus Required for Phosphoethanolamine Modification of the Salmonella enterica Serovar Typhimurium Lipopolysaccharide Core

2005 ◽  
Vol 187 (10) ◽  
pp. 3391-3399 ◽  
Author(s):  
R. Tamayo ◽  
B. Choudhury ◽  
A. Septer ◽  
M. Merighi ◽  
R. Carlson ◽  
...  
Keyword(s):  
Surface Charge ◽  
Salmonella Enterica ◽  
Lipid A ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Regulatory System ◽  
Polymyxin B ◽  
Serovar Typhimurium ◽  
Antimicrobial Peptide Resistance

ABSTRACT In response to the in vivo environment, the Salmonella enterica serovar Typhimurium lipopolysaccharide (LPS) is modified. These modifications are controlled in part by the two-component regulatory system PmrA-PmrB, with the addition of 4-aminoarabinose (Ara4N) to the lipid A and phosphoethanolamine (pEtN) to the lipid A and core. Here we demonstrate that the PmrA-regulated STM4118 (cptA) gene is necessary for the addition of pEtN to the LPS core. pmrC, a PmrA-regulated gene necessary for the addition of pEtN to lipid A, did not affect core pEtN addition. Although imparting a similar surface charge modification as Ara4N, which greatly affects polymyxin B resistance and murine virulence, neither pmrC nor cptA plays a dramatic role in antimicrobial peptide resistance in vitro or virulence in the mouse model. Therefore, factors other than surface charge/electrostatic interaction contribute to resistance to antimicrobial peptides such as polymyxin B.

scholarly journals Toll-Like Receptor 4 Protects against Lethal Leptospira interrogans Serovar Icterohaemorrhagiae Infection and Contributes to In Vivo Control of Leptospiral Burden

2006 ◽  
Vol 74 (2) ◽  
pp. 887-895 ◽  
Author(s):  
Suganya Viriyakosol ◽  
Michael A. Matthias ◽  
Mark A. Swancutt ◽  
Theo N. Kirkland ◽  
Joseph M. Vinetz
Keyword(s):  
Pulmonary Hemorrhage ◽  
Polymyxin B ◽  
Peritoneal Macrophages ◽  
Mouse Strains ◽  
Leptospira Interrogans ◽  
Necrosis Factor Alpha ◽  
Cytokine Responses ◽  
Inflammatory Protein ◽  
Severe Leptospirosis

ABSTRACTThe roles of innate immune responses in protection from or pathogenesis of severe leptospirosis remain unclear. We examined the role of Toll-like receptors (TLRs) in mouse infection and macrophage responses toLeptospira. C3H/HeJ mice (TLR4 deficient) and C3H/HeJ-SCID mice, but not C3H/OuJ mice (TLR4 intact), died after intraperitoneal infection withLeptospira interrogansserovar Icterohaemorrhagiae. Death in both C3H/HeJ mouse strains was associated with jaundice and pulmonary hemorrhage, similar to the patient from whom the isolate was obtained. In chronic sublethal infection, TLR4-deficient mice harbored more leptospires in liver, lung, and kidney than control mice. Heat-killedLeptospirastimulated macrophages to secrete proinflammatory cytokines, tumor necrosis factor alpha, interleukin-6, and macrophage inflammatory protein 2 not inhibited by polymyxin B, suggesting that leptospiral lipopolysaccharide (LPS) did not drive these responses. Anti-TLR4 and anti-MD-2 but not anti-CD14 monoclonal antibodies inhibited cytokine production. Peritoneal macrophages from CD14−/−and TLR2−/−mice exhibited no defect in cytokine responses toLeptospiracompared to controls. Macrophages from C3H/HeJ, TLR4−/−, and MyD88−/−mice secreted far-lower levels of cytokines than wild-type macrophages in response toLeptospira. TLR4 plays a crucial role in protection from acute lethal infection and control of leptospiral burden during sublethal chronic infection. Cytokine responses in macrophages correlated with leptospiral clearance. These TLR4-dependent but CD14/TLR2-independent responses are likely mediated by a leptospiral ligand(s) other than LPS.

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