| In recent years,the incidence of food allergy has increased greatly,which has become a hot issue in the field of public health and food safety.Recent studies indicate that the occurrence and development of food allergy is closely related to the intestinal microflora structure and intestinal mucosal immune imbalance.Olive oil is rich in unsaturated fatty acids,β-sitosterol,oleuropein and other active ingredients,which can regulate intestinal microbiota and intestinal immunity.However,studies on the effects of olive oil on food allergies are rarely reported.In this research,a food allergy mouse model was established to explore the dose-effect relationship of virgin olive oil on food allergy.The effects of different edible vegetable oils and main active ingredients in virgin olive oil on food allergy were compared.The regulation of olive oil and its active components on intestinal mucosal barrier function and intestinal microflora structure in allergic mice was further studied,and the mechanism of action of virgin olive oil in preventing food allergy was preliminarily revealed.The main results are as follows:1.Construction of animal model of food allergy and intervention of olive oil on food allergy.An animal model of food allergy was established with BALB/ C mice as experimental animals,Ovalbumin(OVA)as allergen and Cholera toxin(CT)as immune adjuvant.The sensitized mice showed hypothermia,nasal scratching,convulsions,asthma and other allergic symptoms.Serum OVA-Ig E,OVA-Ig G and histamine levels were 7.77 μg/m L,220.36 μg/L and 7.69 μg/L,respectively.After 7 weeks of continuous indosages of 1.0,2.0 and 3.0 g/kg,the allergic symptoms of mice in each group were significantly improved in a dose-dependent manner.Compared with model group,serum levels of OVA-Ig E,OVA-Ig G and histamine in high-dose group decreased by 70.40%,71.22% and 72.99%,respectively,and the expression level of m MCP-1,an inflammatory medium in intestinal mucosa,was decreased by 54.31%2.Comparison of effects of different edible Vegetable oils on food allergy and analysis of main active components in olive oil.The effects of soybean oil,peanut oil,tea oil and olive oil on food allergy in mice were compared at the same dose(3.0 g/kg).The results showed that soybean oil and peanut oil had no intervention effect on food allergy,but both tea oil and olive oil could effectively improve the clinical symptoms of allergy in mice and reduce the levels of serum allergy-related factors.Further analysis of the anti-allergic active ingredients of olive oil showed that oleic acid(1.58-2.37 g/kg),β-sitosterol(10.0-20.0 mg/kg)and oleuropein(10.0-20.0mg/kg)all have a significant improvement effect on food allergy in mice.3.Effects of olive oil and its main nutrients on intestinal barrier function in food allergic mice.After the mice were allergic,the level of intestinal mucin 2 increased from 212.97 pg/m L to 350.44 pg/m L,and the expression of TNF-α increased by 1.21 times,accompanied by intestinal inflammation such as villus atrophy and breakage,widening of the gap between intestinal glands,etc.At the same time,the levels of Th2-type response factors IL-1β and IL-4increased by 69.82% and 61.77%,respectively,indicating imbalance of intestinal immunity.After olive oil intervention,the levels of intestinal mucin 2 and inflammatory factor TNF-αdecreased to 233.21 pg/m L and 115.91 ng/L,respectively,which were not significantly different from the normal group.Meanwhile,the expression of IL-1β and IL-4 was down-regulated by36.97% and 32.08%,respectively.Compared with the model group,the expression of IL-22 in the intestinal epithelium of mice in the olive oil treatment group increased significantly,and the expression of tight junction proteins(Claudins,Occludin,and ZO-1)increased by 85.01%,39.93%,and 54.80%,respectively.Moreover,the levels of antimicrobial peptide RegⅢγ and SIg A in intestinal mucus increased by 69.15% and 21.10%,respectively.In terms of intestinal immune balance,olive oil can also effectively promote the expression of IL-10 and TGF-β,and improve allergen tolerance.The effects of oleic acid,β-sitosterol and oleuropein in olive oil on the improvement of the intestinal barrier are different.Oleuropein shows good biological activity in inhibiting the levels of pro-inflammatory T cell related factors,promoting the expression of intestinal epithelial tight junction protein,SIg A and TGF-β.Oleic acid can effectively promote the expression of IL-22 and antibacterial peptide RegⅢγ and inhibit the production of IL-1β and IL-4,while β-sitosterol plays a more active role in up-regulating the level of anti-inflammatory factor IL-10 and reducing mucus overproduction.4.Effects of olive oil on intestinal microflora structure in mice with food allergy.Using 16 S r RNA sequencing technology to analyze the changes in the ileal flora of mice,it was found that the richness and diversity of the intestinal flora of mice with food allergies did not change much,but the composition and structure of the flora changed significantly.At the phylum level,compared with the PBS group,the proportion of Firmicutes in the model group decreased by14.65%,while the proportions of Bacteroides and Proteobacteria increased by 10.87% and4.43%,respectively.At the family level,the proportion of Muribaculaceae and Burkholderiaceae in the model group increased by 11.68% and 5.63%,respectively,and the proportion of Clostridiaceae decreased by 2.01%.After olive oil intervention,the proportion of Burkholderiaceae in the ileum of allergic mice decreased from 8.44% to 1.75%,which was not significantly different from the PBS group.At the same time,the proportion of Clostridiaceae that promote the proliferation of Treg cells increased from 0.47% to 2.48%.It can be seen that improving the structure of the intestinal flora may be an important way for olive oil to prevent food allergies. |
