Lactobacillus Plantarum Lp2 Ameliorates Acute Inflammation And Its Mechanism Induced By LPS-induced In Mice

The inflammatory response is a defense response of the organism to stimuli,which often leads to cardiovascular,respiratory,and gastrointestinal diseases.And there is a lack of ideal preventive drugs in clinical practice.Daily medication not only brings problems such as drug residues and side effects but also is expensive and can disrupt the balance of intestinal flora.Therefore,the development of functional and nutritional foods and the search for green microecological agents will be of great importance in the treatment of inflammatory diseases.Lactobacillus strains were isolated and screened from Northeastern sauerkraut,and the probiotic properties such as antioxidant capacity,acid and bile salt tolerance,antibiotic susceptibility,bacterial inhibitory capacity,and adhesion capacity of Caco-2 cells were determined by extensive in vitro tests.Kunming strain mice were randomly divided into three groups for animal testing,namely,normal diet group(Control group),LPS model group(LPS group),and the group supplemented with the screening strain Lp2 in their daily diet(LPS+Lp2group).The mice were fed for 4 weeks,and the organ coefficients of the liver,thymus,and spleen were measured,the biochemical indexes of serum,liver,and ileal tissues were analyzed,the histopathological changes of liver were observed,and the effect of L.plantarum Lp2 in alleviating the inflammatory response of mice was evaluated;the expression of m RNA and protein in liver and intestine related signaling pathways in mice were detected by RT-PCR and Western blotting techniques to reveal its mechanism of action.The results are as follows:1.Lactobacillus strain Lp2 was screened from traditional Chinese natural fermented foods and identified as L.plantarum,and the probiotic properties analysis revealed that the strain has probiotic properties such as acid and bile salt tolerance,tolerance to gastrointestinal fluids,and inhibition of pathogenic bacteria.L.plantarum Lp2 also has antibiotic susceptibility,exhibiting an unknown susceptibility to kanamycin and streptomycin with minimum inhibitory concentrations of 256 and 128 ?g/m L,respectively;a greater susceptibility to chloramphenicol and tetracycline with minimum inhibitory concentrations of 4 and 8 ?g/m L,respectively;an extreme susceptibility to penicillin tolerance;and a Caco-2 cell adhesion capacity of up to 36.0± 1.0%.2.The results of the LPS-induced acute inflammation mouse model with L.plantarum Lp2 intervention showed that the strain significantly reduced the organ coefficients of liver,spleen,and thymus in mice;L.plantarum Lp2 reduced the increase of ALT and AST levels in mice due to LPS injection,and also reduced the effect of LPS on pro-inflammatory factors such as IL-6,TNF-?,and IL-1?,therefore,L.plantarum Lp2 L.plantarum Lp2 can resist the inflammatory response caused by LPS.3.Western blotting analysis of protein levels of TLR4,ERK,p-ERK,JNK,p-JNK,P38,p-P38,I-?B?,p-I-?B?,NF-?B(p65),p-NF-?B(p65),and Caspase-3 in mouse liver showed that L.plantarum Lp2 regulates MAPK and NF-?B by regulating the phosphorylation of related proteins in MAPK and NF-?B signaling pathways to modulate the inflammatory effects of LPS-induced acute inflammation in mice.4.The protein levels of Nrf2,HO-1 and CYP2E1 in mouse liver,L.plantarum Lp2 was found to up-regulate the expression of Nrf2 and down-regulate the protein levels of CYP2E1 and HO-1.It was shown that L.plantarum Lp2 could activate the Nrf2/HO-1 signaling pathway,which in turn increased the levels of antioxidant enzymes GSH-Px and CAT in mice to alleviate oxidative stress induced by LPS-induced inflammatory response and improve oxidative damage in the liver and intestine.5.L.plantarum Lp2 intervention increased the content of secretory immunoglobulin Ig A in the ileum of mice,significantly increased the protein expression of intestinal tight junction proteins ZO-1,Claudin-1,and Occlaudin.At the same time,it decreased the content of intestinal inflammatory indicators MPO and COX-2 induced by LPS.Thus,L.plantarum Lp2 could alleviate the inflammatory response caused by LPS by modulating intestinal barrier damage.Conclusion: L.plantarum Lp2 is a probiotic strain with anti-inflammatory activity that enhances the immunity of the body.L.plantarum Lp2 alleviates LPS-induced inflammatory responses through modulation of TLR4/MAPK and Nrf2/HO-1/ CYP2E1 signaling pathways and multiple effects of intestinal barrier damage.