Egeal Unit, LaSalle Beauvais Polytechnic Institute, 60026 Beauvais, France.
World J Gastroenterol. 2012 Jun 7;18(21):2619-29. doi: 10.3748/wjg.v18.i21.2619.
To assess whether juvenile chronic ferric iron ingestion limit colitis and dysbiosis at adulthood in rats and mice.
Two sets of experiments were designed. In the first set, recently weaned mice were either orally administered ferrous (Fe²⁺) iron salt or ferric (Fe³⁺) microencapsulated iron for 6 wk. The last week of experiments trinitrobenzene sulfonic acid (TNBS) colitis was induced. In the second set, juvenile rats received the microencapsulated ferric iron for 6 wk and were also submitted to TNBS colitis during the last week of experiments. In both sets of experiments, animals were sacrificed 7 d after TNBS instillation. Severity of the inflammation was assessed by scoring macroscopic lesions and quantifying colonic myeloperoxidase (MPO) activity. Alteration of the microflora profile was estimated using quantitative polymerase chain reaction (qPCR) by measuring the evolution of total caecal microflora, Bacteroidetes, Firmicutes and enterobacteria.
Neither ferrous nor ferric iron daily exposures at the juvenile period result in any effect in control animals at adulthood although ferrous iron repeated administration in infancy limited weight gain. Ferrous iron was unable to limit the experimental colitis (1.71 ± 0.27 MPO U/mg protein vs 2.47 ± 0.22 MPO U/mg protein in colitic mice). In contrast, ferric iron significantly prevented the increase of MPO activity (1.64 ± 0.14 MPO U/mg protein) in TNBS-induced colitis. Moreover, this positive effect was observed at both the doses of ferric iron used (75 and 150 mg/kg per day po--6 wk). In the study we also compared, in both rats and mice, the consequences of chronic repeated low level exposure to ferric iron (75 mg/kg per day po--6 wk) on TNBS-induced colitis and its related dysbiosis. We confirmed that ferric iron limited the TNBS-induced increase of MPO activity in both the rodent species. Furthermore, we assessed the ferric iron incidence on TNBS-induced intestinal microbiota dysbiosis. At first, we needed to optimize the isolation and quantify DNA copy numbers using standard curves to perform by qPCR this interspecies comparison. Using this approach, we determined that total microflora was similar in control rats and mice and was mainly composed of Firmicutes and Bacteroidetes at a ratio of 10/1. Ferric juvenile administration did not modify the microflora profile in control animals. Total microflora numbers remained unchanged whichever experimental conditions studied. Following TNBS-induced colitis, the Firmicutes/Bacteroidetes ratio was altered resulting in a decrease of the Firmicutes numbers and an increase of the Bacteroidetes numbers typical of a gut inflammatory reaction. In parallel, the subdominant population, the enterobacteria was also increased. However, ferric iron supplementation for the juvenile period prevented the increase of Bacteroidetes and of enterobacteria numbers consecutive to the colitis in both the studied species at adulthood.
Rats and mice juvenile chronic ferric iron ingestion prevents colitis and dysbiosis at adulthood as assessed by the first interspecies comparison.
评估幼年时慢性摄入亚铁（Fe²⁺）或三价铁（Fe³⁺）微胶囊铁是否会限制成年大鼠和小鼠的结肠炎和肠道菌群失调。
设计了两组实验。在第一组实验中，最近断奶的小鼠经口给予亚铁（Fe²⁺）盐或三价铁（Fe³⁺）微胶囊铁 6 周。实验的最后一周，给予三硝基苯磺酸（TNBS）结肠炎诱导。在第二组实验中，幼年大鼠接受微胶囊铁 6 周，并在实验的最后一周也接受 TNBS 结肠炎。在两组实验中，动物在 TNBS 灌注后 7 天处死。通过评分宏观病变和定量结肠髓过氧化物酶（MPO）活性来评估炎症的严重程度。通过定量聚合酶链反应（qPCR）测量总盲肠微生物群、拟杆菌门、厚壁菌门和肠杆菌的演变来估计微生物群谱的变化。
幼年时期无论是摄入亚铁还是三价铁都不会对成年期的对照组动物产生任何影响，尽管亚铁铁重复给药在婴儿期限制了体重增加。亚铁不能限制实验性结肠炎（1.71±0.27MPO U/mg 蛋白与结肠炎小鼠中的 2.47±0.22MPO U/mg 蛋白）。相比之下，三价铁显著预防了 TNBS 诱导的结肠炎中 MPO 活性的增加（1.64±0.14MPO U/mg 蛋白）。此外，这种积极的影响在使用的两种三价铁剂量（75 和 150mg/kg 每日 po-6 周）中都观察到。在这项研究中，我们还比较了在大鼠和小鼠中，慢性重复低水平暴露于三价铁（75mg/kg 每日 po-6 周）对 TNBS 诱导的结肠炎及其相关的肠道菌群失调的影响。我们证实三价铁限制了两种啮齿动物的 TNBS 诱导的 MPO 活性增加。此外，我们评估了三价铁对 TNBS 诱导的肠道微生物群失调的影响。首先，我们需要优化分离和使用标准曲线定量 DNA 拷贝数，以便通过 qPCR 进行种间比较。使用这种方法，我们确定了对照组大鼠和小鼠的总微生物群相似，主要由厚壁菌门和拟杆菌门组成，比例为 10/1。幼年铁给药不会改变对照组动物的微生物群谱。无论研究哪种实验条件，总微生物群数量都保持不变。在 TNBS 诱导的结肠炎后，厚壁菌门/拟杆菌门的比例发生改变，导致厚壁菌门数量减少，拟杆菌门数量增加，这是肠道炎症反应的典型特征。同时，亚优势种群，肠杆菌也增加了。然而，幼年时期补充三价铁可预防两种研究物种在成年期结肠炎后厚壁菌门和肠杆菌数量的增加。
大鼠和小鼠幼年慢性三价铁摄入可预防成年期结肠炎和肠道菌群失调，这是首次进行种间比较得出的结论。
