Chao Fang, Pan Ren, Yejun He, Yitian Wang, Shuting Yao, Congying Zhao, Xueyong Li, Xi Zhang, Jinqing Li, Mingkai Li
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引用次数: 0
Abstract
Background: Mitochondria play a crucial role in shaping the macrophage inflammatory response during bacterial infections. Spinster homolog 2 (Spns2), responsible for sphingosine-1-phosphate (S1P) secretion, acts as a key regulator of mitochondrial dynamics in macrophages. However, the link between Spns2/S1P signaling and mitochondrial functions remains unclear.
Methods: Peritoneal macrophages were isolated from both wild-type and Spns2 knockout rats, followed by non-targeted metabolomics and RNA sequencing analysis to identify the potential mediators through which Spns2/S1P signaling influences the mitochondrial functions in macrophages. Various agonists and antagonists were used to modulate the activation of Spns2/S1P signaling and its downstream pathways, with the underlying mechanisms elucidated through western blotting. Mitochondrial functions were assessed using flow cytometry and oxygen consumption assays, as well as morphological analysis. The impact on inflammatory response was validated through both in vitro and in vivo sepsis models, with the specific role of macrophage-expressed Spns2 in sepsis evaluated using Spns2flox/floxLyz2-Cre mice. Additionally, the regulation of mitochondrial functions by Spns2/S1P signaling was confirmed using THP-1 cells, a human monocyte-derived macrophage model.
Results: In this study, we unveil prostaglandin E2 (PGE2) as a pivotal mediator involved in Spns2/S1P-mitochondrial communication. Spns2/S1P signaling suppresses PGE2 production to support malate-aspartate shuttle activity. Conversely, excessive PGE2 resulting from Spns2 deficiency impairs mitochondrial respiration, leading to intracellular lactate accumulation and increased reactive oxygen species (ROS) generation through E-type prostanoid receptor 4 activation. The overactive lactate-ROS axis contributes to the early-phase hyperinflammation during infections. Prolonged exposure to elevated PGE2 due to Spns2 deficiency culminates in subsequent immunosuppression, underscoring the dual roles of PGE2 in inflammation throughout infections. The regulation of PGE2 production by Spns2/S1P signaling appears to depend on the coordinated activation of multiple S1P receptors rather than any single one.
Conclusions: These findings emphasize PGE2 as a key effector of Spns2/S1P signaling on mitochondrial dynamics in macrophages, elucidating the mechanisms through which Spns2/S1P signaling balances both early hyperinflammation and subsequent immunosuppression during bacterial infections.
期刊介绍:
Cell Communication and Signaling (CCS) is a peer-reviewed, open-access scientific journal that focuses on cellular signaling pathways in both normal and pathological conditions. It publishes original research, reviews, and commentaries, welcoming studies that utilize molecular, morphological, biochemical, structural, and cell biology approaches. CCS also encourages interdisciplinary work and innovative models, including in silico, in vitro, and in vivo approaches, to facilitate investigations of cell signaling pathways, networks, and behavior.
Starting from January 2019, CCS is proud to announce its affiliation with the International Cell Death Society. The journal now encourages submissions covering all aspects of cell death, including apoptotic and non-apoptotic mechanisms, cell death in model systems, autophagy, clearance of dying cells, and the immunological and pathological consequences of dying cells in the tissue microenvironment.