resolvin-d1 and Escherichia-coli-Infections

Bacterial pneumonia is a leading cause of morbidity and mortality worldwide. Host responses to contain infection and mitigate pathogen-mediated lung inflammation are critical for pneumonia resolution. Aspirin-triggered resolvin D1 (AT-RvD1; 7S,8R,17R-trihydroxy-4Z,9E,11E,13Z,15E,19Z-docosahexaenoic acid) is a lipid mediator (LM) that displays organ-protective actions in sterile lung inflammation, and regulates pathogen-initiated cellular responses. Here, in a self-resolving murine model of Escherichia coli pneumonia, LM metabololipidomics performed on lungs obtained at baseline, 24, and 72 h after infection uncovered temporal regulation of endogenous AT-RvD1 production. Early treatment with exogenous AT-RvD1 (1 h post infection) enhanced clearance of E. coli and Pseudomonas aeruginosa in vivo, and lung macrophage phagocytosis of fluorescent bacterial particles ex vivo. Characterization of macrophage subsets in the alveolar compartment during pneumonia identified efferocytosis by infiltrating macrophages (CD11b(Hi) CD11c(Low)) and exudative macrophages (CD11b(Hi) CD11c(Hi)). AT-RvD1 increased efferocytosis by these cells ex vivo, and accelerated neutrophil clearance during pneumonia in vivo. These anti-bacterial and pro-resolving actions of AT-RvD1 were additive to antibiotic therapy. Taken together, these findings suggest that the pro-resolving actions of AT-RvD1 during pneumonia represent a novel host-directed therapeutic strategy to complement the current antibiotic-centered approach for combatting infections.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Aspirin; Bronchoalveolar Lavage Fluid; Docosahexaenoic Acids; Escherichia coli; Escherichia coli Infections; Gene Expression; Lipid Metabolism; Lipids; Lipocalin-2; Lung; Macrophages, Alveolar; Male; Mice; Mice, Inbred C57BL; Neutrophils; Phagocytosis; Pneumonia, Bacterial; Pseudomonas aeruginosa; Pseudomonas Infections

Local mediators orchestrate the host response to both sterile and infectious challenge and resolution. Recent evidence demonstrates that maresin sulfido-conjugates actively resolve acute inflammation and promote tissue regeneration. In this report, we investigated self-limited infectious exudates for novel bioactive chemical signals in tissue regeneration and resolution. By use of spleens from Escherichia coli infected mice, self-resolving infectious exudates, human spleens, and blood from patients with sepsis, we identified 2 new families of potent molecules. Characterization of their physical properties and isotope tracking demonstrated that the bioactive structures contained a docosahexaenoate backbone and sulfido-conjugated triene or tetraene double-bond systems. Activated human phagocytes converted 17-hydro(peroxy)-4Z,7Z,10Z,13Z,15E,19Z-docosahexaenoic acid to these bioactive molecules. Regeneration of injured planaria was accelerated with nanomolar amounts of 16-glutathionyl, 17-hydroxy-4Z,7Z,10,12,14,19Z-docosahexaenoic acid and 16-cysteinylglycinyl, 17-hydroxy-4Z,7Z,10,12,14,19Z-docosahexaenoic acid (Protectin sulfido-conjugates) or 8-glutathionyl, 7,17-dihydroxy-4Z,9,11,13Z,15E,19Z-docosahexaenoic acid and 8-cysteinylglycinyl, 7,17-dihydroxy-4Z,9,11,13Z,15E,19Z-docosahexaenoic acid (Resolvin sulfido-conjugates). Each protectin and resolvin sulfido-conjugate dose dependently (0.1-10 nM) stimulated human macrophage bacterial phagocytosis, phagolysosomal acidification, and efferocytosis. Together, these results identify 2 novel pathways and provide evidence for structural elucidation of new resolution moduli. These resolvin and protectin conjugates identified in mice and human infected tissues control host responses promoting catabasis.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; CD59 Antigens; Cells, Cultured; Chromatography, Liquid; Docosahexaenoic Acids; Escherichia coli; Escherichia coli Infections; Humans; Inflammation; Inflammation Mediators; Leukocytes, Mononuclear; Macrophages; Mice; Peritonitis; Phagocytosis; Planarians; Regeneration; Sepsis; Spleen; Tandem Mass Spectrometry

Resolution of inflammation is an active process driven by several new families of endogenous lipid mediators collectively coined specialized proresolving mediators (SPM). Here, we report a synthetic analog of resolvin D1 (RvD1) and aspirin-triggered RvD1, benzo-diacetylenic-17R-RvD1-methyl ester (BDA-RvD1), which was prepared using fewer steps than required for total organic synthesis of natural SPM. BDA-RvD1 was resistant to further metabolism by human recombinant 15-prostaglandin dehydrogenase, a major inactivation pathway for RvD1. In ischemia-reperfusion-initiated second organ injury, BDA-RvD1 intravenously (1 μg) reduced neutrophil infiltration into the lungs by 58 ± 9% and was significantly more potent than native RvD1. BDA-RvD1 at 100 ng/mouse also shortened the resolution interval, Ri, of Escherichia coli peritonitis with a similar potency as RvD1, by ~57%, from Ri 10.5 h to 4.5 h. With isolated human phagocytes, BDA-RvD1 at picomolar concentrations (10(-12) M) stimulated phagocytosis of zymosan A particles. BDA-RvD1 activated human recombinant G protein-coupled receptor 32/DRV1, an RvD1 receptor, in a dose-dependent manner. These results indicate that, both in vivo in mice and with isolated human cells, BDA-RvD1 shares defining proresolving actions of RvD1, including inhibiting leukocyte infiltration and stimulating phagocytosis. Moreover, they provide evidence for a new analog mimetic and example of an immunoresolvent, namely an agent that stimulates active resolution of inflammation, for a potential new therapeutic class.

Topics: Animals; Cells, Cultured; Docosahexaenoic Acids; Escherichia coli; Escherichia coli Infections; Esters; Humans; Inflammation; Lung; Macrophages; Mice; Neutrophil Infiltration; Peritonitis; Phagocytes; Phagocytosis; Receptors, G-Protein-Coupled; Reperfusion Injury; Zymosan

Underlying mechanisms for how bacterial infections contribute to active resolution of acute inflammation are unknown. Here, we performed exudate leukocyte trafficking and mediator-metabololipidomics of murine peritoneal Escherichia coli infections with temporal identification of pro-inflammatory (prostaglandins and leukotrienes) and specialized pro-resolving mediators (SPMs). In self-resolving E. coli exudates (10(5) colony forming units, c.f.u.), the dominant SPMs identified were resolvin (Rv) D5 and protectin D1 (PD1), which at 12 h were at significantly greater levels than in exudates from higher titre E. coli (10(7) c.f.u.)-challenged mice. Germ-free mice had endogenous RvD1 and PD1 levels higher than in conventional mice. RvD1 and RvD5 (nanograms per mouse) each reduced bacterial titres in blood and exudates, E. coli-induced hypothermia and increased survival, demonstrating the first actions of RvD5. With human polymorphonuclear neutrophils and macrophages, RvD1, RvD5 and PD1 each directly enhanced phagocytosis of E. coli, and RvD5 counter-regulated a panel of pro-inflammatory genes, including NF-κB and TNF-α. RvD5 activated the RvD1 receptor, GPR32, to enhance phagocytosis. With self-limited E. coli infections, RvD1 and the antibiotic ciprofloxacin accelerated resolution, each shortening resolution intervals (R(i)). Host-directed RvD1 actions enhanced ciprofloxacin's therapeutic actions. In 10(7) c.f.u. E. coli infections, SPMs (RvD1, RvD5, PD1) together with ciprofloxacin also heightened host antimicrobial responses. In skin infections, SPMs enhanced vancomycin clearance of Staphylococcus aureus. These results demonstrate that specific SPMs are temporally and differentially regulated during infections and that they are anti-phlogistic, enhance containment and lower antibiotic requirements for bacterial clearance.

Topics: Animals; Anti-Bacterial Agents; Docosahexaenoic Acids; Escherichia coli; Escherichia coli Infections; Humans; Hypothermia; Macrophages; Male; Mice; Mice, Inbred C57BL; Microbial Viability; Neutrophils; Peritonitis; Phagocytosis; Skin Diseases; Staphylococcal Infections; Staphylococcus aureus; Vancomycin

Detection and clearance of bacterial infection require balanced effector and resolution signals to avoid chronic inflammation. Detection of GNB LPS by TLR4 on m induces inflammatory responses, contributing to chronic inflammation and tissue injury. LXs and Rvs are endogenous lipid mediators that enhance resolution of inflammation, and their actions on primary human m responses toward GNB are largely uncharacterized. Here, we report that LXA(4), LXB(4), and RvD1, tested at 0.1-1 μM, inhibited LPS-induced TNF production from primary human m, with ATL and 17(R)-RvD1, demonstrating potent inhibition at 0.1 μM. In addition, 17(R)-RvD1 inhibited LPS-induced primary human m production of IL-7, IL-12p70, GM-CSF, IL-8, CCL2, and MIP-1α without reducing that of IL-6 or IL-10. Remarkably, when stimulated with live Escherichia coli, m treated with 17(R)-RvD1 demonstrated increased TNF production and enhanced internalization and killing of the bacteria. 17(R)-RvD1-enhanced TNF, internalization, and killing were not evident for an lpxM mutant of E. coli expressing hypoacylated LPS with reduced inflammatory activity. Furthermore, 17(R)-RvD1-enhanced, E. coli-induced TNF production was evident in WT but not TLR4-deficient murine m. Thus, Rvs differentially modulate primary human m responses to E. coli in an LPS- and TLR4-dependent manner, such that this Rv could promote resolution of GNB/LPS-driven inflammation by reducing m proinflammatory responses to isolated LPS and increasing m responses important for clearance of infection.

Topics: Animals; Blotting, Western; Cell Adhesion Molecules; Cell Differentiation; Cell Proliferation; Cytokines; Docosahexaenoic Acids; Enzyme-Linked Immunosorbent Assay; Escherichia coli; Escherichia coli Infections; Humans; Inflammation Mediators; Lipopolysaccharides; Macrophages; Mice; Mutation; Phosphoproteins; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Toll-Like Receptor 4