coliinfection (106CFU, IB) and treatment with ciprofloxacin (0, 0. 2, 2, and 20 mg/kg, IP). macrophage, lipid mediator, AT-RvD1 == Introduction == One critical function of the acute inflammatory host response to infection is delivery of leukocytes to sites of tissue injury to protect the host from microbial invasion and restore homeostasis1. If Compound K unrestrained in both amplitude and duration, persistent lung and airway infiltration by neutrophils can result in collateral injury to healthy bystander tissue, leading to organ damage and loss of function2. In health, inflammatory responses are self-limited with essential fatty acid derived specialized pro-resolving mediator (SPM) signaling pivotal to the arrest of inflammation and initiation of resolution1. Aspirin-triggered resolvin D1 (AT-RvD1; 7S, 8R, 17R trihydroxy-4Z, 9E, 11E, 13Z, 15E, 19Z docosahexaenoic acid) was first identified as a product of aspirin acetylated cyclooxygenase-23, 4. It is now clear that AT-RvD1 is a docosahexaenoic acid (DHA) derived SPM that can also be produced endogenously in the Compound K absence of aspirin by a second pathway initiated by cytochrome P450 enzymes5. AT-RvD1 potently decreases acute lung inflammation after mucosal injury6; however , its role in pneumonia remains to be characterized. Bacterial pneumonia is a leading cause of mortality and morbidity worldwide, accounting for over 110 million years of life lost in 20107. Gram-negative bacterial pneumonia is the most common life-threatening hospital acquired infection8. In the United States, pneumonia causes more disease and death than any other infection, and there has been little change in pneumonia-associated mortality for more than five decades9. Currently, antibiotics are C1qdc2 the cornerstone of therapy; however , the rise of antibiotic-resistant microorganisms emphasizes a need for a new approach that augments host defense mechanisms to microbial invasion10. Stimulation of bacterial clearance and counter regulation of inflammatory responses are defining features of SPMs11. Given its potent actions in regulating sterile lung inflammation6, and pathogen-initiated cellular responsesin vitro12, we hypothesized that the SPM AT-RvD1 would be produced during pneumonia to limit infection and ensuing inflammatory responses. Alveolar macrophages are tissue resident cells with key functions in pathogen recognition, initiation of host defense via protective inflammation, and in clearance of invading microbes11. Additional macrophage subsets infiltrate the alveolar space during the course of pathogen-mediated acute lung inflammation13to augment the resident macrophage protective actions14. Of interest, macrophages carry the biosynthetic and molecular circuitry to produce and respond to SPM1. Here, in a self-resolving murine model ofEscherichia coli(E. coli) pneumonia, AT-RvD1 was produced in a temporally regulated and enhanced gram-negative bacterial clearance and resolution of pathogen-initiated lung inflammation. == Materials and methods == == Materials == AT-RvD1 (7S, 8R, 17R-trihydroxy-4Z, 9E, 11E, 13Z, 15E, 19Z-docosahexaenoic acid) was obtained from Cayman Chemical (Ann Arbor, MI, USA) and validated just prior to use with LC-MS-MS and physical criteria reported earlier15. E. coli(O6: K2: H1) strain ATCC 19138 andPseudomonas aeruginosa(P. aeruginosa; HER-1018) strain ATCC BAA-47 were obtained from the American Compound K Type Culture Collection (Manassas, VA, USA). E. coliparticles conjugated Compound K with pHrodo were purchased from Life Technologies (Carlsbad, CA, USA). Lipopolysaccharide (LPS, E. coliO55: B5), ciprofloxacin, and hydrochloric acid (HCl) were purchased from Sigma-Aldrich (St. Louis, MO, USA). FACS antibodies were obtained from eBioscience (San Diego, CA, USA): F4/80 (BM8); Biolegend (San Diego, CA, USA): CD11b (M1/70), and Ly6G (1A8); BD Biosciences (San Diego, CA, USA): CD11c (HL3), CD45 (30-F11). Permeabilization buffer was purchased from eBioscience. == Mice == C57BL/6 male mice (810 wk old, body weights 2025 g; Charles River Laboratories, Wilmington, MA, USA) were housed in isolation cages in pathogen-free conditions on a lightdark cycle with light from 7: 00 to 20: 00 at 25C. Mice were fed a standard diet (Laboratory Rodent Diet 5001; PMI Nutrition International, St . Louis, MO, USA) containing 4. 5% total fat with 0. 3% -3 fatty acids and <0. 02% C20: 4 and were provided water ad libitum. All studies were assessed and given the green light by the Harvard Medical Spot.
VIP Receptors