title: Expression and function of Toll-like receptors in chicken heterophils.
abstract: The heterophil is the major polymorphonuclear cell in birds with a functional capacity akin to that of the mammalian neutrophil. Herein, we demonstrate that heterophils constitutively express TLR1/6/10, TLR2 type 1, TLR2 type 2, TLR3, TLR4, TLR5, and TLR7 mRNA. Furthermore, TLR agonists, including flagellin (from Salmonella typhimurium, FGN), peptidoglycan (from Staphylococcus aureus, PGN), ultra-pure lipopolysaccharide (from Salmonella minnesota, LPS), the synthetic double stranded RNA analog [poly(I:C)], and the guanosine analog, loxoribine (LOX) directly induced both an oxidative burst and a degranulation response. Interestingly, the synthetic bacterial lipoprotein Pam3CSK4 (palmitoyl-3-cysteine-serine-lysine-4, PAM) induced degranulation, but no oxidative burst. The bacterial TLR agonists (PAM, PGN, LPS, and FGN) all induced an up-regulation of expression of mRNA of the pro-inflammatory cytokines IL-1beta, IL-6, and IL-8; whereas both poly(I:C) and LOX induced a down-regulation of these cytokine mRNAs. Stimulation of heterophils with each specific TLR agonist led to a differential increase in the phosphorylation of both p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase 1/2 (ERK 1/2) activation, but not the phosphorylation of c-Jun NH2-terminal kinase (JNK). The broad TLR expression profile in heterophils reflects their principal role as first line effector cells in avian host defense against bacterial, viral, fungal, and parasitic infections. The results demonstrate the differential involvement of TLR-induced signals in the stimulation of transduction pathways that regulate the oxygen-dependent and -independent antimicrobial defense mechanisms of avian heterophils.
authors.affiliation: USDA-ARS, Southern Plains Agricultural Research Center, 2881 F&B Road, College Station, TX 77845, USA. kogut@ffsru.tamu.edu
authors.forename: Michael H
authors.initials: MH
authors.lastname: Kogut
authors.forename: Muhammad
authors.initials: M
authors.lastname: Iqbal
authors.forename: Haiqi
authors.initials: H
authors.lastname: He
authors.forename: Victoria
authors.initials: V
authors.lastname: Philbin
authors.forename: Pete
authors.initials: P
authors.lastname: Kaiser
authors.forename: Adrian
authors.initials: A
authors.lastname: Smith
mesh_terms: D000818:Animals; D001483:Base Sequence; D015550:Cell Degranulation; D002645:Chickens / Q000235:genetics* / Q000276:immunology*; D016207:Cytokines / Q000235:genetics; D005408:Flagellin / Q000494:pharmacology; D015870:Gene Expression; D006151:Guanosine / Q000031:analogs & derivatives / Q000494:pharmacology; D066298:In Vitro Techniques; D018836:Inflammation Mediators / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008562:Membrane Glycoproteins / Q000819:agonists / Q000235:genetics* / Q000276:immunology*; D009504:Neutrophils / Q000187:drug effects / Q000276:immunology / Q000502:physiology; D010457:Peptidoglycan / Q000494:pharmacology; D011070:Poly I-C / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000819:agonists / Q000235:genetics* / Q000276:immunology*; D016897:Respiratory Burst; D051194:Toll-Like Receptor 1; D051195:Toll-Like Receptor 2; D051196:Toll-Like Receptor 3; D051197:Toll-Like Receptor 4; D051198:Toll-Like Receptor 5; D051199:Toll-Like Receptor 7; D051193:Toll-Like Receptors
chemical_list: D016207:Cytokines; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D010457:Peptidoglycan; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D051194:Toll-Like Receptor 1; D051195:Toll-Like Receptor 2; D051196:Toll-Like Receptor 3; D051197:Toll-Like Receptor 4; D051198:Toll-Like Receptor 5; D051199:Toll-Like Receptor 7; D051193:Toll-Like Receptors; D006151:Guanosine; D005408:Flagellin; C068562:loxoribine; D011070:Poly I-C