Cytochrome c modulates the mitochondrial signaling pathway and polymorphonuclear neutrophil apoptosis in bile duct-ligated rats

Abstract

Abstract. It has been observed that polymorphonuclear neutrophils (PMN) increase in number and function during obstructive jaundice (OJ). However, the precise mechanisms underlying PMN apoptosis during OJ remain poorly understood. The aim of the present study was to investigate the modulation of cytochrome c (Cytc) on the mitochondrial signaling pathway in bile duct-ligated (BDL) rats and the effect on PMN apoptosis following the intravenous administration of Cytc. Rats were randomly divided into four groups: A control group, a sham group, a BDL group and a BDL + Cytc group (rats with common bile duct ligation as well as Cytc intravenous injection). Blood samples were collected from the inferior vein cava for biochemical analysis and separation of the PMN. PMN apoptosis was evaluated using flow cytometry. The mitochondrial membrane potential (ΔΨm) of PMN was detected by rhodamine-123 staining. The Cytc protein expression levels were examined using western blotting. PMN mitochondria were observed using transmission electron microscopy. The results of the present study revealed that the PMN apoptosis rate in rats decreased gradually from 12 to 72 h following BDL to levels that were significantly lower than those of the control group and the sham group. Compared with the corresponding time point of the BDL group, the BDL + Cytc group showed a significantly increased PMN apoptosis rate. The mean fluorescence intensity (MFI) of ΔΨm decreased from 12 to 72 h following BDL, and was significantly increased compared with the control and sham groups. MFI in the BDL + Cytc group was higher compared with that in the BDL group. Cytc expression levels increased in the mitochondria and decreased in the cytoplasm from the 12 to 72 h in the BDL group, which was significantly different from that in the control and sham groups at the corresponding time points. Compared with the BDL group, Cytc expression levels in the cytoplasm for the BDL + Cytc group tended to gradually and significantly increase. Morphological changes in PMN mitochondria were marginal in BDL rats and marked in the BDL + Cytc group. In the BDL rats, PMN apoptosis was inhibited, a process induced by the mitochondrial apoptotic signaling pathway in which Cytc has an important role. High ΔΨm in the mitochondria and decreased Cytc expression levels in the cytoplasm result in PMN apoptosis inhibition. Intravenous injection of Cytc may help compensate for the lack of Cytc proteins in the cytoplasm, inducing PMN apoptosis following BDL.

Neutrophil extracellular traps enhance procoagulant activity and thrombotic tendency in patients with obstructive jaundice

“…The existence and function of the neutrophils in OJ are the focus of many studies, which have demonstrated overproduction of neutrophils in human bone marrow and inhibition of PMN apoptosis in mice, leading to increased neutrophils counts 12,13 . However, little was known about the fate of the neutrophils in OJ.…”

“…OJ patients had increased neutrophil counts 12 . Furthermore, neutrophil apoptosis was inhibited in bile duct‐ligated rats, 13 as well as aberrant phagocytic function 14 . Notably, these neutrophil dysfunctions were corrected after biliary drainage 10,14 .…”

The Phenotype and Metabolism Relationship of Blood Neutrophils in Patients With Widespread Purulent Peritonitis in the Postoperative Period Dynamics

“…Подобное состояние двух оксидоредуктаз цикла Кребса характеризует субстратный поток высокой интенсивности, что положительно повлияет на активность аэроб-ного дыхания. Необходимо отметить, аэробное дыхание вносит незначительный вклад в общую энергетику нейтрофильных гранулоцитов, од-нако высокая активность дыхательной цепи мо-жет стимулировать вхождение клетки в апоптоз [12,21]. На 24 сутки послеоперационного периода у больных РГП в нейтрофилах крови наблюдает-ся значительное снижение активности НАДН-зависимой реакции МДГ.…”

“…Экспрессия рецепторов для Fc-фрагмента иммуноглобулинов на поверхности нейтрофилов формирует пул армированных фагоцитов, участвующих в процессе антитело-зависимой цитотоксичности [10,11,26]. Учи-тывая, что все регуляторные и антигенные мо-лекулы реализуют свое воздействие на клетку через рецепторы, влияя на экспрессию генов, модулируя энергетические и пластические реакции, функциональные проявления ней-трофилов не могут не иметь метаболической основы [3,12,23]. РГП сопровождается избы-точным поступлением в биологические среды организма микробных антигенов и бактери-альных токсинов, источниками которых явля-ются гнойно-деструктивные очаги в брюшной полости, перитонеальный экссудат и парали-тически измененные петли кишечника [4,18].…”

Inhibition of Caveolae Contributes to Propofol Preconditioning‐Suppressed Microvesicles Release and Cell Injury by Hypoxia‐Reoxygenation

“…It has been demonstrated that I/R-induced oxidative stress is a pivotal factor which leads to mitochondrial dysfunction [ 7 ]. I/R induced the upregulation of proapoptotic protein Bax and downregulation of antiapoptotic protein BCL2 which will lead to mitochondrial membrane permeability changes (the mitochondrial permeability transition pore (MPTP) opening, which in turn triggers apoptosis) and the loss of transmembrane potential [ 8 ]; then, cytochrome c and other proteins will be released from the mitochondria into the cytoplasm, which was considered to be a critical step in the mitochondrial apoptotic pathway [ 9 ]; finally, cytochrome c released into the cytoplasm induced caspase activation and cell apoptosis [ 10 ]. Therefore, maintaining EC and mitochondrial functional stability is a corking therapeutic strategy for mitigation of I/R injury.…”