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.

4-Aroyl-3-hydroxy-5-phenyl-1H-pyrrol-2(5H)-ones as N-formyl peptide receptor 1 (FPR1) antagonists

“…Neutrophils play an essential role in proper resolution of inflammation, and when these processes are not tightly regulated, neutrophils can trigger positive feedback amplification loops that promote neutrophil chemotaxis, adherence to endothelial cells, and activation, leading to significant tissue damage and evolution toward chronic disease [52]. Recently, Honda et al [53] demonstrated that FPR1 blockade by cyclosporine H attenuated hepatic ischemia-reperfusion injury by inhibition of neutrophil chemotaxis. Thus, the pyrrole-based FPR1 antagonists reported here and their analogs may offer pharmacological means to treat acute and chronic inflammation by reducing FPR1-dependent neutrophil chemotaxis and adherence to epithelial cells.…”

“…Gliadin, the immunogenic component within gluten and a trigger of celiac disease, induces neutrophil migration via engagement of FPR1 [19]. The efficacy of FPR1 blockade in hepatic ischemia-reperfusion injury was reported recently [20]. In addition, an aurantiamide analog HCH6–1 demonstrated protective effects on lipopolysaccharide-induced acute lung injury by blocking FPR1 in mice [21, 22].…”

Exosomes Derived from Dendritic Cells Attenuate Liver Injury by Modulating the Balance of Treg and Th17 Cells After Ischemia Reperfusion

“…In particular, acute kidney injury (AKI) after liver I/R is common (40–85% incidence) and greatly increases patient mortality and morbidity during the perioperative period [1-5]. Therefore, reducing the adverse effects of I/R injury (IRI) will increase the lifespan of patients after hepatic surgeries.…”

Mitochondrial damage–associated molecular patterns released by lung transplants are associated with primary graft dysfunction

“…In agreement with this observation, we detected FPR1-dependent neutrophil transmigration across a mouse epithelial monolayer in response to N-formylated peptides. Recent evidence shows that infiltrating neutrophils tend to accumulate in nonperfused areas following IRI 48 and that their prolonged retention promotes tissue injury. 26 These reports led us to determine if FPR1 promotes neutrophil retention within damaged airways.…”