Key Laboratory of Animal Feed and Nutrition of Zhejiang Province, College of Animal Sciences, Zhejiang University, Hangzhou, 310058, China.
Sci China Life Sci. 2023 Sep;66(9):2041-2055. doi: 10.1007/s11427-022-2347-0. Epub 2023 Jul 11.
Iron overload often occurs during blood transfusion and iron supplementation, resulting in the presence of non-transferrin-bound iron (NTBI) in host plasma and damage to multiple organs, but effects on the intestine have rarely been reported. In this study, an iron overload mouse model with plasma NTBI was established by intraperitoneal injection of iron dextran. We found that plasma NTBI damaged intestinal morphology, caused intestinal oxidative stress injury and reactive oxygen species (ROS) accumulation, and induced intestinal epithelial cell apoptosis. In addition, plasma NTBI increased the relative abundance of Ileibacterium and Desulfovibrio in the cecum, while the relative abundance of Faecalibaculum and Romboutsia was reduced. Ileibacterium may be a potential microbial biomarker of plasma NTBI. Based on the function prediction analysis, plasma NTBI led to the weakening of intestinal microbiota function, significantly reducing the function of the extracellular structure. Further investigation into the mechanism of injury showed that iron absorption in the small intestine significantly increased in the iron group. Caco-2 cell monolayers were used as a model of the intestinal epithelium to study the mechanism of iron transport. By adding ferric ammonium citrate (FAC, plasma NTBI in physiological form) to the basolateral side, the apparent permeability coefficient (Papp) values from the basolateral to the apical side were greater than 3×10 cm s. Intracellular ferritin level and apical iron concentration significantly increased, and SLC39A8 (ZIP8) and SLC39A14 (ZIP14) were highly expressed in the FAC group. Short hairpin RNA (shRNA) was used to knock down ZIP8 and ZIP14 in Caco-2 cells. Transfection with ZIP14-specific shRNA decreased intracellular ferritin level and inhibited iron uptake. These results revealed that plasma NTBI may cause intestinal injury and intestinal flora dysbiosis due to the uptake of plasma NTBI from the basolateral side into the small intestine, which is probably mediated by ZIP14.
铁过载通常发生在输血和补铁过程中，导致宿主血浆中存在非转铁蛋白结合铁（NTBI），并损害多个器官，但对肠道的影响很少有报道。在这项研究中，通过腹腔注射右旋糖酐铁建立了一个具有血浆 NTBI 的铁过载小鼠模型。我们发现，血浆 NTBI 破坏了肠道形态，导致肠道氧化应激损伤和活性氧（ROS）积累，并诱导肠道上皮细胞凋亡。此外，血浆 NTBI 增加了盲肠中 Ileibacterium 和 Desulfovibrio 的相对丰度，而 Faecalibaculum 和 Romboutsia 的相对丰度降低。Ileibacterium 可能是血浆 NTBI 的潜在微生物生物标志物。基于功能预测分析，血浆 NTBI 导致肠道微生物群落功能减弱，显著降低了细胞外结构的功能。进一步研究损伤机制表明，铁组小肠铁吸收显著增加。使用 Caco-2 细胞单层作为肠道上皮模型，研究铁转运的机制。通过在基底外侧侧添加柠檬酸铁铵（FAC，生理形式的血浆 NTBI），从基底外侧到顶端侧的表观渗透系数（Papp）值大于 3×10 cm s。细胞内铁蛋白水平和顶端铁浓度显著增加，并且在 FAC 组中 SLC39A8（ZIP8）和 SLC39A14（ZIP14）高度表达。使用短发夹 RNA（shRNA）敲低 Caco-2 细胞中的 ZIP8 和 ZIP14。转染 ZIP14 特异性 shRNA 降低了细胞内铁蛋白水平并抑制了铁摄取。这些结果表明，由于从基底外侧侧摄取血浆 NTBI 进入小肠，血浆 NTBI 可能导致肠道损伤和肠道菌群失调，这可能是由 ZIP14 介导的。
