scholarly journals Efferocytosis-induced prostaglandin E2 production impairs alveolar macrophage effector functions during Streptococcus pneumoniae infection

2016 ◽  
Vol 23 (3) ◽  
pp. 219-227 ◽  
Author(s):  
Ana CG Salina ◽  
Tais P Souza ◽  
Carlos H Serezani ◽  
Alexandra I Medeiros
Keyword(s):  
Streptococcus Pneumoniae ◽  
Prostaglandin E2 ◽  
Mannose Receptor ◽  
Scavenger Receptors ◽  
Apoptotic Cells ◽  
Jurkat T Cells ◽  
Bacterial Killing ◽  
Effector Functions ◽  
Ep Receptor ◽  
Pka Pathway

Alveolar macrophages (AMs) are multitasking cells that maintain lung homeostasis by clearing apoptotic cells (efferocytosis) and performing antimicrobial effector functions. Different PRRs have been described to be involved in the binding and capture of non-opsonized Streptococcus pneumoniae, such as TLR-2, mannose receptor (MR) and scavenger receptors (SRs). However, the mechanism by which the ingestion of apoptotic cells negatively influences the clearance of non-opsonized S. pneumoniae remains to be determined. In this study, we evaluated whether the prostaglandin E2 (PGE2) produced during efferocytosis by AMs inhibits the ingestion and killing of non-opsonized S. pneumoniae. Resident AMs were pre-treated with an E prostanoid (EP) receptor antagonist, inhibitors of cyclooxygenase and protein kinase A (PKA), incubated with apoptotic Jurkat T cells, and then challenged with S. pneumoniae. Efferocytosis slightly decreased the phagocytosis of S. pneumoniae but greatly inhibited bacterial killing by AMs in a manner dependent on PGE2 production, activation of the EP2–EP4/cAMP/PKA pathway and inhibition of H2O2 production. Our data suggest that the PGE2 produced by AMs during efferocytosis inhibits H2O2 production and impairs the efficient clearance non-opsonized S. pneumoniae by EP2–EP4/cAMP/PKA pathway.

scholarly journals Pharmacodynamics of Moxifloxacin and Levofloxacin at Simulated Epithelial Lining Fluid Drug Concentrations against Streptococcus pneumoniae

2004 ◽  
Vol 48 (4) ◽  
pp. 1215-1221 ◽  
Author(s):  
Naomi R. Florea ◽  
Pamela R. Tessier ◽  
Cuilian Zhang ◽  
Charles H. Nightingale ◽  
David P. Nicolau
Keyword(s):  
Streptococcus Pneumoniae ◽  
Fluoroquinolone Resistance ◽  
Epithelial Lining ◽  
Time Curve ◽  
Bacterial Killing ◽  
Epithelial Lining Fluid ◽  
Log Reduction ◽  
Development Of Resistance ◽  
Drug Concentrations

ABSTRACT Recent clinical failures associated with levofloxacin treatment for Streptococcus pneumoniae infections and growing evidence of frequent mutations in the isolate population have led to increased concerns regarding fluoroquinolone resistance. Our objective was to characterize the efficacies of levofloxacin and moxifloxacin against various genotypes of S. pneumoniae after simulated bronchopulmonary exposures. An in vitro model was used to simulate a levofloxacin concentration of 500 mg and a moxifloxacin concentration of 400 mg, which were previously determined to be the concentrations in the epithelial lining fluid of older adults receiving once-daily dosing. The effects of the drugs were tested against six S. pneumoniae containing various mutations. Bacterial density and resistance were quantitatively assessed over 48 h. The S. pneumoniae isolate with no mutation displayed a 4-log reduction in CFU after treatment with both agents and did not develop resistance. Isolates containing the parC or parE mutation or both mutations regrew and developed resistance when they were exposed to levofloxacin, despite an unbound area under the concentration-time curve (AUC):MIC ratio of ∼100. When the isolate containing the parC and gyrA mutations was exposed to levofloxacin, there was a half-log reduction in the number of CFU compared to that for the control, but the isolate subsequently regrew. Likewise, levofloxacin did not kill the isolate containing the parC, gyrA, and parE mutations. Moxifloxacin sustained the killing of all bacterial isolates tested without the development of resistance. Levofloxacin did not sustain bacterial killing and did not prevent the emergence of further resistance in mutants with the parC or parE mutation or both mutations, even though an unbound AUC:MIC ratio for exposure well above the breakpoint of 30 to 40 established in the literature for S. pneumoniae was maintained. Moxifloxacin was effective against all isolates tested, despite the presence of isolates with two- and three-step mutations, for which the MICs were increased.

scholarly journals Prostaglandin E2 activates the mTORC1 pathway through an EP4/cAMP/PKA- and EP1/Ca2+-mediated mechanism in the human pancreatic carcinoma cell line PANC-1

2015 ◽  
Vol 309 (10) ◽  
pp. C639-C649 ◽  
Author(s):  
Hui-Hua Chang ◽  
Steven H. Young ◽  
James Sinnett-Smith ◽  
Caroline Ei Ne Chou ◽  
Aune Moro ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Pancreatic Cancer ◽  
Prostaglandin E2 ◽  
Human Pancreatic Cancer ◽  
Pancreatic Carcinoma Cell Line ◽  
Pancreatic Cancer Cells ◽  
Mtorc1 Signaling ◽  
Mtorc1 Pathway ◽  
Pka Pathway ◽  
Mtorc1 Activation

Obesity, a known risk factor for pancreatic cancer, is associated with inflammation and insulin resistance. Proinflammatory prostaglandin E2 (PGE2) and elevated insulin-like growth factor type 1 (IGF-1), related to insulin resistance, are shown to play critical roles in pancreatic cancer progression. We aimed to explore a potential cross talk between PGE2 signaling and the IGF-1/Akt/mammalian target of rapamycin complex 1 (mTORC1) pathway in pancreatic cancer, which may be a key to unraveling the obesity-cancer link. In PANC-1 human pancreatic cancer cells, we showed that PGE2 stimulated mTORC1 activity independently of Akt, as evaluated by downstream signaling events. Subsequently, using pharmacological and genetic approaches, we demonstrated that PGE2-induced mTORC1 activation is mediated by the EP4/cAMP/PKA pathway, as well as an EP1/Ca2+-dependent pathway. The cooperative roles of the two pathways were supported by the maximal inhibition achieved with the combined pharmacological blockade, and the coexistence of highly expressed EP1 (mediating the Ca2+ response) and EP2 or EP4 (mediating the cAMP/PKA pathway) in PANC-1 cells and in the prostate cancer line PC-3, which also robustly exhibited PGE2-induced mTORC1 activation, as identified from a screen in various cancer cell lines. Importantly, we showed a reinforcing interaction between PGE2 and IGF-1 on mTORC1 signaling, with an increase in IL-23 production as a cellular outcome. Our data reveal a previously unrecognized mechanism of PGE2-stimulated mTORC1 activation mediated by EP4/cAMP/PKA and EP1/Ca2+ signaling, which may be of great importance in elucidating the promoting effects of obesity in pancreatic cancer. Ultimately, a precise understanding of these molecular links may provide novel targets for efficacious interventions devoid of adverse effects.

scholarly journals Streptococcus pneumoniae DNA Gyrase and Topoisomerase IV: Overexpression, Purification, and Differential Inhibition by Fluoroquinolones

1999 ◽  
Vol 43 (5) ◽  
pp. 1129-1136 ◽  
Author(s):  
Xiao-Su Pan ◽  
L. Mark Fisher
Keyword(s):  
Streptococcus Pneumoniae ◽  
Dna Gyrase ◽  
Dna Supercoiling ◽  
Topoisomerase Iv ◽  
T7 Promoter ◽  
Bacterial Killing ◽  
E Coli ◽  
Apparent Homogeneity ◽  
Comparable Activity

ABSTRACT Streptococcus pneumoniae gyrA and gyrBgenes specifying the DNA gyrase subunits have been cloned into pET plasmid vectors under the control of an inducible T7 promoter and have been separately expressed in Escherichia coli. Soluble 97-kDa GyrA and 72-kDa GyrB proteins bearing polyhistidine tags at their respective C-terminal and N-terminal ends were purified to apparent homogeneity by one-step nickel chelate column chromatography and were free of host E. coli topoisomerase activity. Equimolar amounts of the gyrase subunits reconstituted ATP-dependent DNA supercoiling with comparable activity to gyrase of E. coli and Staphylococcus aureus. In parallel, S. pneumoniae topoisomerase IV ParC and ParE subunits were similarly expressed in E. coli, purified to near homogeneity as 93- and 73-kDa proteins, and shown to generate efficient ATP-dependent DNA relaxation and DNA decatenation activities. Using the purified enzymes, we examined the inhibitory effects of three paradigm fluoroquinolones—ciprofloxacin, sparfloxacin, and clinafloxacin—which previous genetic studies with S. pneumoniae suggested act preferentially through topoisomerase IV, through gyrase, and through both enzymes, respectively. Surprisingly, all three quinolones were more active in inhibiting purified topoisomerase IV than gyrase, with clinafloxacin showing the greatest inhibitory potency. Moreover, the tested agents were at least 25-fold more effective in stabilizing a cleavable complex (the relevant cytotoxic lesion) with topoisomerase IV than with gyrase, with clinafloxacin some 10- to 32-fold more potent against either enzyme, in line with its superior activity againstS. pneumoniae. The uniform target preference of the three fluoroquinolones for topoisomerase IV in vitro is in apparent contrast to the genetic data. We interpret these results in terms of a model for bacterial killing by quinolones in which cellular factors can modulate the effects of target affinity to determine the cytotoxic pathway.

Gastric Cytoprotection by Prostaglandin E2 — Relation to EP Receptor Subtypes —

2002 ◽  
pp. 169-180
Author(s):  
Koji Takeuchi ◽  
Shinichi Kato ◽  
Yusaku Komoike ◽  
Yoshihiro Ogawa ◽  
Masanori Takeeda
Keyword(s):  
Prostaglandin E2 ◽  
Receptor Subtypes ◽  
Gastric Cytoprotection ◽  
Ep Receptor

scholarly journals Amoxicillin Is Effective against Penicillin-Resistant Streptococcus pneumoniae Strains in a Mouse Pneumonia Model Simulating Human Pharmacokinetics

2006 ◽  
Vol 51 (1) ◽  
pp. 208-214 ◽  
Author(s):  
Pierre Abgueguen ◽  
Esther Azoulay-Dupuis ◽  
Violaine Noel ◽  
Pierre Moine ◽  
Veronique Rieux ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Survival Rates ◽  
Detection Threshold ◽  
Treatment Completion ◽  
Community Acquired Pneumonia ◽  
High Dose ◽  
Human Pharmacokinetics ◽  
Bacterial Clearance ◽  
Bacterial Killing ◽  
Tolerant Strain

ABSTRACT High-dose oral amoxicillin (3 g/day) is the recommended empirical outpatient treatment of community-acquired pneumonia (CAP) in many European guidelines. To investigate the clinical efficacy of this treatment in CAP caused by Streptococcus pneumoniae strains with MICs of amoxicillin ≥2 μg/ml, we used a lethal bacteremic pneumonia model in leukopenic female Swiss mice with induced renal failure to replicate amoxicillin kinetics in humans given 1 g/8 h orally. Amoxicillin (15 mg/kg of body weight/8 h subcutaneously) was given for 3 days. We used four S. pneumoniae strains with differing amoxicillin susceptibility and tolerance profiles. Rapid bacterial killing occurred with an amoxicillin-susceptible nontolerant strain: after 4 h, blood cultures were negative and lung homogenate counts under the 2 log10 CFU/ml detection threshold (6.5 log10 CFU/ml in controls, P < 0.01). With an amoxicillin-intermediate nontolerant strain, significant pulmonary bacterial clearance was observed after 24 h (4.3 versus 7.9 log10 CFU/ml, P < 0.01), and counts were undetectable 12 h after treatment completion. With an amoxicillin-intermediate tolerant strain, 24-h bacterial clearance was similar (5.4 versus 8.3 log10 CFU/ml, P < 0.05), but 12 h after treatment completion, lung homogenates contained 3.3 log10 CFU/ml. Similar results were obtained with an amoxicillin-resistant and -tolerant strain. Day 10 survival rates were usually similar across strains. Amoxicillin with pharmacokinetics simulating 1 g/8 h orally in humans is bactericidal in mice with pneumonia due to S. pneumoniae for which MICs were 2 to 4 μg/ml. The killing rate depends not only on resistance but also on tolerance of the S. pneumoniae strains.

scholarly journals Host Cell Lipid Bodies Triggered by Trypanosoma cruzi Infection and Enhanced by the Uptake of Apoptotic Cells Are Associated With Prostaglandin E2 Generation and Increased Parasite Growth

2011 ◽  
Vol 204 (6) ◽  
pp. 951-961 ◽  
Author(s):  
Heloisa D’Avila ◽  
Célio G. Freire-de-Lima ◽  
Natalia R. Roque ◽  
Livia Teixeira ◽  
Christina Barja-Fidalgo ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Prostaglandin E2 ◽  
Host Cell ◽  
Parasite Growth ◽  
Apoptotic Cells ◽  
Lipid Bodies ◽  
Cell Lipid ◽  
Cruzi Infection

scholarly journals Immunoglobulin A-Mediated Protection against Bordetella pertussis Infection

2001 ◽  
Vol 69 (8) ◽  
pp. 4846-4850 ◽  
Author(s):  
Sandra M. M. Hellwig ◽  
Annemiek B. van Spriel ◽  
Joop F. P. Schellekens ◽  
Frits R. Mooi ◽  
Jan G. J. van de Winkel
Keyword(s):  
Transgenic Mice ◽  
Bordetella Pertussis ◽  
Polymorphonuclear Leukocytes ◽  
Whooping Cough ◽  
Immunoglobulin A ◽  
Pertussis Infection ◽  
Bacterial Killing ◽  
Effector Functions ◽  
Human Polymorphonuclear Leukocytes

ABSTRACT Infection with Bordetella pertussis, the causative agent of pertussis (whooping cough) in humans, is followed by the production of antibodies of several isotypes, including immunoglobulin A (IgA). Little is known, however, about the role of IgA in immunity against pertussis. Therefore, we studied targeting ofB. pertussis to the myeloid receptor for IgA, FcαRI (CD89), using either IgA purified from immune sera of pertussis patients or bispecific antibodies directed against B. pertussis and FcαRI (CD89 BsAb). Both IgA and CD89 BsAb facilitated FcαRI-mediated binding, phagocytosis, and bacterial killing by human polymorphonuclear leukocytes (PMNL) and PMNL originating from human FcαRI-transgenic mice. Importantly, FcαRI targeting resulted in enhanced bacterial clearance in lungs of transgenic mice. These data support the capacity of IgA to induce anti-B. pertussis effector functions via the myeloid IgA receptor, FcαRI. Increasing the amount of IgA antibodies induced by pertussis vaccines may result in higher vaccine efficacy.

scholarly journals Pharmacodynamic Modeling of Clarithromycin against Macrolide-Resistant [PCR-Positive mef(A) or erm(B)] Streptococcus pneumoniae Simulating Clinically Achievable Serum and Epithelial Lining Fluid Free-Drug Concentrations

2002 ◽  
Vol 46 (12) ◽  
pp. 4029-4034 ◽  
Author(s):  
Ayman M. Noreddin ◽  
Danielle Roberts ◽  
Kim Nichol ◽  
Aleksandra Wierzbowski ◽  
Daryl J. Hoban ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Compartment Model ◽  
Free Drug ◽  
Pharmacodynamic Modeling ◽  
Epithelial Lining ◽  
Bacterial Killing ◽  
Epithelial Lining Fluid ◽  
Initial Inoculum ◽  
Drug Concentrations

ABSTRACT The association between macrolide resistance mechanisms and clinical outcomes remains understudied. The present study, using an in vitro pharmacodynamic model, assessed clarithromycin (CLR) activity against mef(A)-positive and erm(B)-negative Streptococcus pneumoniae isolates by simulating free-drug concentrations in serum and both total (protein-bound and free) and free drug in epithelial lining fluid (ELF). Five mef(A)-positive and erm(B)-negative strains, one mef(A)-negative and erm(B)-positive strain, and a control [mef(A)-negative and erm(B)-negative] strain of S. pneumoniae were tested. CLR was modeled using a one-compartment model, simulating a dosage of 500 mg, per os, twice a day (in serum, free-drug Cp maximum of 2 μg/ml, t 1/2 of 6 h; in ELF, C ELF(total) maximum of 35μg/ml, t 1/2 of 6 h; CELF(free) maximum of 14 μg/ml, t 1/2 of 6 h). Starting inocula were 106 CFU/ml in Mueller-Hinton broth with 2% lysed horse blood. With sampling at 0, 4, 8, 12, 20, and 24 h, the extent of bacterial killing was assessed. Achieving CLR T/MIC values of ≥90% (AUC0-24/MIC ratio, ≥61) resulted in bacterial eradication, while T>MIC values of 40 to 56% (AUC0-24/MIC ratios of ≥30.5 to 38) resulted in a 1.2 to 2.0 log10 CFU/ml decrease at 24 h compared to that for the initial inoculum. CLR T/MIC values of ≤8% (AUC0-24/MIC ratio, ≤17.3) resulted in a static effect or bacterial regrowth. The high drug concentrations in ELF that were obtained clinically with CLR may explain the lack of clinical failures with mef(A)-producing S. pneumoniae strains, with MICs up to 8 μg/ml. However, mef(A) isolates for which MICs are ≥16 μg/ml along with erm(B) may result in bacteriological failures.

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