title: Mammalian target of rapamycin regulates IL-10 and resistance to Pseudomonas aeruginosa corneal infection.
abstract: IL-10 is important in the resistance response of BALB/c mice to experimental Pseudomonas aeruginosa corneal infection. However, the cellular mechanisms by which this anti-inflammatory cytokine is regulated remain unknown. Because the mammalian target of rapamycin (mTOR) regulates IL-10 in other disease models, the present study tested its role in bacterial keratitis. After infection, corneas of rapamycin versus control-treated BALB/c mice showed worsened disease, and real-time RT-PCR confirmed that mTOR mRNA levels were significantly decreased. Rapamycin treatment also increased clinical score, polymorphonuclear neutrophil (PMN) infiltration (determined by myeloperoxidase assay), and bacterial load, but it diminished PMN bactericidal activity. Inhibition of mTOR also led to elevated mRNA and protein levels of IL-12p40, matrix metalloproteinase 9, and inducible NO synthase, whereas mRNA and protein levels of IL-10, its regulator/effector STAT-3, and suppressor of cytokine signaling 3 (a proinflammatory cytokine regulator) were decreased. Furthermore, mTOR inhibition reduced levels of proapoptotic caspase-3 and increased levels of B cell lymphoma-2 (antiapoptotic), indicative of delayed apoptosis. mTOR inhibition also altered genes related to TLR signaling, including elevation of TLR4, TLR5, and IL-1R1, with decreases in IL-1R-associated kinase 1 and an inhibitor of NF-κB, NF-κB inhibitor-like 1. Rapamycin treatment also increased levels of IFN-γ and CCAAT/enhancer binding protein, β, a gene that regulates expression of preprotachykinin-A (the precursor of substance P). Collectively, these data, as well as a rescue experiment using rIL-10 together with rapamycin, which decreased PMN in cornea, provide concrete evidence that mTOR regulates IL-10 in P. aeruginosa-induced bacterial keratitis and is critical to balancing pro- and anti-inflammatory events, resulting in better disease outcome.
authors.affiliation: Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
authors.forename: Megan E B
authors.initials: ME
authors.lastname: Foldenauer
authors.forename: Sharon A
authors.initials: SA
authors.lastname: McClellan
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Berger
authors.forename: Linda D
authors.initials: LD
authors.lastname: Hazlett
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D058491:Bacterial Load; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000235:genetics / Q000378:metabolism; D016207:Cytokines / Q000235:genetics / Q000276:immunology; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D016753:Interleukin-10 / Q000235:genetics / Q000378:metabolism*; D007634:Keratitis / Q000276:immunology* / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D051379:Mice; D020556:Neutrophil Infiltration / Q000276:immunology; D009504:Neutrophils / Q000276:immunology; D009573:Nitrites / Q000378:metabolism; D009195:Peroxidase / Q000378:metabolism; D010587:Phagocytosis; D011552:Pseudomonas Infections / Q000276:immunology* / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D011550:Pseudomonas aeruginosa / Q000276:immunology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051193:Toll-Like Receptors / Q000235:genetics / Q000378:metabolism
chemical_list: D022782:CCAAT-Enhancer-Binding Protein-beta; C545013:Cebpb protein, mouse; D016207:Cytokines; D009573:Nitrites; D012333:RNA, Messenger; D050796:STAT3 Transcription Factor; D051193:Toll-Like Receptors; D016753:Interleukin-10; D009195:Peroxidase; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus