Department of Critical Care Medicine, Zhongnan Hospital, Wuhan University, Wuhan, Hubei, China.
Clinical Research Center of Hubei Critical Care Medicine, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, China.
Inflammation. 2024 Feb;47(1):454-468. doi: 10.1007/s10753-023-01928-w. Epub 2023 Nov 18.
Besides being recognized by membrane receptor TLR4, lipopolysaccharide (LPS) can also be internalized into the cytosol and activate Caspase-4/11 pyroptotic pathways to further amplify inflammation in sepsis. The objective of this study was to investigate whether Galectin-3 (Gal3) could promote the uptake of LPS by governing RAGE or administering endocytosis, consequently activating Caspase 4/11 and mediating pyroptosis in sepsis-associated acute kidney injury (SA-AKI). By pinpointing Gal3, LPS, and EEA1 (endosome-marker) or LAMP1 (lysosome-marker) respectively, immunofluorescence discovered that Gal3 and LPS were mainly aggregated in early endosomes initially and translocated into lysosomes afterwards. In cells and animal models, Gal3 and the Caspase-4/11 pathways were simultaneously activated, and the overexpression of Gal3 could exacerbate pyroptosis, whereas inhibition of Gal3 or the knockdown of its expression could ameliorate pyroptosis, reduce the pathological changes of SA-AKI and improve the survival of the animals with SA-AKI. Silencing RAGE reduced pyroptosis in primary tubular epithelial cells (PTCs) activated by Gal3 and LPS but not in cells activated by Gal3 and outer membrane vesicles (with LPS inside), whereas pyroptosis in both was reduced by blockade of Gal3, indicating Gal3 promoted pyroptosis through both RAGE-dependent and RAGE-independent pathways. Our investigation further revealed a positive correlation between serum Gal3 and pyroptotic biomarkers IL-1 beta and IL-18 in patients with sepsis, and that serum Gal3 was an independent risk factor for mortality. Through our collective exploration, we unraveled the significant role of Gal3 in the internalization of LPS and the provocation of more intense pyroptosis, thus making it a vital pathogenic factor in SA-AKI and a possible therapeutic target. Gal3 enabled the internalization of endotoxin into endosomes and lysosomes via both RAGE-dependent (A) and RAGE-independent (B) pathways, leading to pyroptosis. The suppression of Gal3 curbed Caspase4/11 noncanonical inflammasomes and diminished sepsis and SA-AKI.
除了被膜受体 TLR4 识别外，脂多糖 (LPS) 还可以被内吞进入细胞质，并激活 Caspase-4/11 细胞焦亡途径，从而在脓毒症中进一步放大炎症。本研究旨在探讨 Galectin-3 (Gal3) 是否可以通过调控 RAGE 或内吞作用来促进 LPS 的摄取，进而激活 Caspase 4/11，介导脓毒症相关急性肾损伤 (SA-AKI) 中的细胞焦亡。通过分别针对 Gal3、LPS 和内体标志物 EEA1（早期内体标志物）或溶酶体标志物 LAMP1（溶酶体标志物）进行免疫荧光，发现 Gal3 和 LPS 主要聚集在早期内体中，随后转移到溶酶体中。在细胞和动物模型中，Gal3 和 Caspase-4/11 途径同时被激活，Gal3 的过表达可加重细胞焦亡，而 Gal3 的抑制或表达下调可减轻细胞焦亡，改善 SA-AKI 的病理变化并提高 SA-AKI 动物的存活率。沉默 RAGE 可减少 Gal3 和 LPS 激活的原代肾小管上皮细胞 (PTCs)中的细胞焦亡，但对 Gal3 和含有 LPS 的外膜囊泡激活的细胞无效，而 Gal3 阻断则可减少两者的细胞焦亡，表明 Gal3 通过 RAGE 依赖和非依赖途径促进细胞焦亡。我们的研究进一步表明，脓毒症患者血清 Gal3 与细胞焦亡生物标志物 IL-1β和 IL-18 呈正相关，且血清 Gal3 是死亡的独立危险因素。通过我们的综合研究，揭示了 Gal3 在 LPS 内化和引发更强烈细胞焦亡中的重要作用，使其成为 SA-AKI 的重要致病因素和可能的治疗靶点。Gal3 通过 RAGE 依赖 (A) 和非 RAGE 依赖 (B) 途径将内毒素内化到内体和溶酶体中，引发细胞焦亡。Gal3 抑制可抑制 Caspase4/11 非经典炎性小体并减轻脓毒症和 SA-AKI。
