Regulation Mechanism Of Lacticaseibacillus Casei Zhang On The Gut Microbiota Of Mice Fed With High-iron Diet

With the development of the pharmaceutical industry and the improvement of People’s living standards,there are more and more iron supplements and iron fortified foods appear on the market,however,excessive iron supplementation is potentially harmful to the health of the host and the homeostasis of gut microbiota.Studies of dietary iron have focused on iron deficiency,and the effects of the high-iron diets on the structure and function of gut microbiota have been poorly studied.Many studies show that probiotics can improve the health status of patients with anemia and iron deficiency by regulating the gut microbiota,there are few reports on the regulation of gut microbiota by intake of high-iron diet and probiotics.Whether probiotics can regulate the gut microbiota and improve iron homeostasis under high-iron stress is studied,this is of great significance for broadening the choice of "healthy iron supplement".In this study,C57BL/6N mice were used as the research object and the metagenomics method was used as the main research technique to design a mouse model of iron excess intake on a high-iron diet for eight weeks,this study aimed to explore the differences between the gut microbiota and the apparent indexes in mice,and to screen the important immune factors in response to the high-iron diet by using immune chip technology,CRISPR was then used to construct gene-deficient mice to test the relationship between host genes and gut microbiota in the context of the high iron diet,the aim of this study was to investigate whether Lacticaseibacillus casei Zhang could play an advantageous role on the function and structure of gut microbiota in the context of the high-iron diet.The results are as follows:(1)The serum iron homeostasis and gut microbiota balance of C57BL/6 mice fed a high-iron diet for 8 weeks were impaired,and the serum IL-22 concentration was increased.The impairment of serum iron homeostasis was mainly manifested by the increase of serum iron concentration and the decrease of serum total iron-binding capacity.The dysbacteriosis mainly showed that Bacteroidetes of mice fed a high-iron diet increased significantly,and the function of the microbiome has also changed significantly,in addition to the adverse effects of long-term consumption of high-iron diet on gut microbiota and serum iron homeostasis,LCZ can improve total iron-binding capacity in mice,LCZ intervention can enhance the stability of mice microbiota by activating negative feedback and inhibiting positive feedback in the species interaction network.(2)IL-22 knockout mice and wild-type mice showed completely different microbiota structures.Under the stress of excessive iron in the diet,the individual’s genetic background and the characteristics of gut microbiota may lead to the difference in the metabolism of macro and micronutrients in the microbiota,interleukin-22(IL-22)gene is the key gene that controls the stability of macro/micronutrient metabolism in microbiota.Through the analysis of the structure of flora data,it was found that the deletion of mouse IL-22 gene had an inhibitory effect on the scale of Bacteroidetes.Alistipes and Bacteroides are highly sensitive to the high-iron diet,while the "sensitivity" of Muribaculum bacteria does not respond strongly to the condition of IL-22 gene deletion.(3)This study found that Parabacteroides goldsteinii is an important flora marker of excessive dietary iron intake.LCZ intervention can improve its relative abundance in the intestine and make it closer to the normal level.(4)In the context of the high-iron diet,the relative abundance of Firmicutes was not affected by the high-iron diet as compared with the sensitive Bacteroidetes bacteria,and this was not only a phenomenon in wild-type C57BL/6 mice,in the IL-22 gene knockout mice,this phenomenon still exists.It is found that Firmicutes show inertia under high-iron nutrition in the mice’s gut.(5)LCZ can modulate gut microbiota disturbance in mice fed a high-iron diet,but the feedback of gut microbiota to serum iron homeostasis needs the support of the IL-22 gene.In the context of a high-iron diet,the bacterial network involved in the IL-22 gene and the regulation of Bacteroidetes are the key factors for LCZ to regulate the structure and metabolic function of microbiota and serum iron homeostasis in high-iron diet mice,it is also a key mechanism for LCZ to be effective.