title: Intravital Imaging of Neutrophil Recruitment Reveals the Efficacy of FPR1 Blockade in Hepatic Ischemia-Reperfusion Injury.
abstract: Neutrophils are considered responsible for the pathophysiological changes resulting from hepatic ischemia-reperfusion (I/R) injury, which is a complication of trauma, shock, liver resection, and transplantation. Recently, evidence is accumulating that formyl-peptide receptor (FPR) signaling constitutes an important danger signal that guides neutrophils to sites of inflammation. This study aimed to investigate dynamic neutrophil recruitment using two-photon laser-scanning microscopy (TPLSM) in response to FPR1 blockade during hepatic I/R. LysM-eGFP mice were subjected to partial warm hepatic I/R. They were pretreated with an FPR1 antagonist, cyclosporine H (CsH), or formyl peptide, fMLF. Liver was imaged after hepatic laser irradiation or I/R using the TPLSM technique. CsH treatment alleviated hepatic I/R injury, as evidenced by decreased serum transaminase levels, reduced hepatocyte necrosis/apoptosis, and diminished inflammatory cytokine, chemokine, and oxidative stress. In contrast, systemic administration of fMLF showed few effects. Time-lapse TPLSM showed that FPR1 blockade inhibited the accumulation of neutrophils in the necrotic area induced by laser irradiation in vivo. In the CsH-treated I/R group, the number and crawling velocity of neutrophils in the nonperfused area were lower than those in the control group. Meanwhile, FPR1 blockade did not affect monocyte/macrophage recruitment. Hepatic I/R promoted the retention of neutrophils and their active behavior in the spleen, whereas CsH treatment prevented their changes. Intravital TPLSM revealed that formyl-peptide-FPR1 signaling is responsible for regulating neutrophil chemotaxis to allow migration into the necrotic area in hepatic I/R. Our findings suggest effective approaches for elucidating the mechanisms of immune cell responses in hepatic I/R.
authors.affiliation: Department of Transplantation and Pediatric Surgery, Postgraduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Honda
authors.affiliation: Department of Transplantation and Pediatric Surgery, Postgraduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
authors.forename: Takayuki
authors.identifier: 0000-0002-6102-3201
authors.initials: T
authors.lastname: Takeichi
authors.affiliation: Department of Transplantation and Pediatric Surgery, Postgraduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
authors.forename: Shintaro
authors.initials: S
authors.lastname: Hashimoto
authors.affiliation: Department of Transplantation and Pediatric Surgery, Postgraduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
authors.forename: Daiki
authors.initials: D
authors.lastname: Yoshii
authors.affiliation: Department of Transplantation and Pediatric Surgery, Postgraduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Isono
authors.affiliation: Department of Transplantation and Pediatric Surgery, Postgraduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
authors.forename: Shintaro
authors.initials: S
authors.lastname: Hayashida
authors.affiliation: Department of Transplantation and Pediatric Surgery, Postgraduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Ohya
authors.affiliation: Department of Transplantation and Pediatric Surgery, Postgraduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Yamamoto
authors.affiliation: Department of Transplantation and Pediatric Surgery, Postgraduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Sugawara
authors.affiliation: Department of Transplantation and Pediatric Surgery, Postgraduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan yino@fc.kuh.kumamoto-u.ac.jp.
authors.forename: Yukihiro
authors.identifier: 0000-0002-7477-9614
authors.initials: Y
authors.lastname: Inomata
mesh_terms: D000818:Animals; D017209:Apoptosis; D018925:Chemokines / Q000276:immunology; D002634:Chemotaxis, Leukocyte; D016572:Cyclosporine / Q000008:administration & dosage; D016207:Cytokines / Q000276:immunology; D000069416:Intravital Microscopy / Q000379:methods; D008099:Liver / Q000000981:diagnostic imaging / Q000187:drug effects / Q000276:immunology* / Q000473:pathology*; D008297:Male; D051379:Mice; D009000:Monocytes / Q000276:immunology; D009336:Necrosis; D020556:Neutrophil Infiltration; D009504:Neutrophils / Q000276:immunology; D044042:Receptors, Formyl Peptide / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000378:metabolism*; D015427:Reperfusion Injury / Q000000981:diagnostic imaging / Q000276:immunology* / Q000503:physiopathology*
chemical_list: D018925:Chemokines; D016207:Cytokines; C469988:Fpr1 protein, mouse; D044042:Receptors, Formyl Peptide; D016572:Cyclosporine; C050025:cyclosporin H