The Alleviate Effect Of Lactate On DSS-induced Colitis Of Piglets

Colitis is a common and complex intestinal inflammatory disease,which is usually caused by the disturbance of the colonic immune response caused by the stimulation of pathogenic factors in the animal body.In animal production,colitis will reduce animal production performance,delay animal growth and development,and increase mortality,resulting in a decrease in breeding income.Lactate,as a metabolite of glycolysis,is closely related to intestinal inflammatory diseases.In this study,two animal experiments were conducted,firstly investigate the changes in the level of lactate in the colon of piglets during the period of inflammation;then,to study the effect of dietary lactate supplementation on the intestinal health,nutrient digestibility and growth performance of piglets with colitis.Experiment 1: Changes of colonic lactate levels in different inflammatory periodsBy comparing the changes of colonic lactate level and inflammatory signalingrelated factors in different inflammatory periods,the experiment aimed to investigate the rule of the changes for lactate during colitis and its relationship with the progress of inflammation.The experiment selected 30 24-day-old DLY weaned piglets with half male and female,good health and similar body weight.After 7 days of feeding with the same diet and management,they were divided into 3 treatments according to the principle of similar body weight and the same sex ratio.10 replicates were processed with 1 piglet per replicate.In the experiment,5% DSS solution was administered to piglets by continuous gavage for 4 days to induce piglet enteritis.Eight piglets were anesthetized and slaughtered on days 0(before DSS induction,control group),5,and 7 days of the experiment,and colon samples were collected to determine the levels of lactate,inflammatory cytokines and signaling pathway-related factors.The results showed that1)Compared with 0 d,the lactate level in colonic mucosa and tissue decreased significantly on 5 d(P < 0.01).Compared with 5 d,the lactate level in colonic mucosa and tissue was significantly increased on 7 d(P < 0.01).2)Compared with 0 d,the m RNA levels of colonic interleukin 10(IL-10)and nucleotide-binding oligomerization protein 2(NOD2)in piglets on 5 d were significantly lower(P < 0.05).Compared with the 5th day of the experiment,the content of IL10 in the colonic mucosa of the piglets showed an increasing trend on the7 th day(P = 0.08).3)3)Compared with 0 d,the m RNA level of c AMP regulatory protein response element(CREM)in the colon of piglets was significantly decreased on 5 d(P < 0.05);colonic mucosa G protein-coupled receptor 81(GPR81),G protein subunit β1(GNB1),hypoxia-inducible factor 1α(HIF-1α),hypoxia-inducible factor 2α(HIF-2α),and Yes-related protein(YAP)levels did not change significantly(P > 0.1).Compared with 5 d,the levels of GPR81,GNB1 and HIF-2α in colonic mucosa were significantly increased on 7 d(P < 0.05);the m RNA level of colonic CREM was significantly increased(P < 0.05).In addition,the colonic mucosa HIF-1α was significantly increased on 7 d compared with 0 d(P < 0.05).The results of this experiment showed that the lactate content in the colon was significantly decreased on the 5 d of the experiment(inflammation peak period);During the inflammation subsidence period,with the increase of lactate content,the content of GPR81 in the colon increased significantly,related immune regulatory pathways were activated,and colon cells secreted anti-inflammatory factors such as IL-10 to promote the resolution of inflammation.Experiment 2: Relief effect of dietary lactate supplementation on inflammatory injury in piglets with colitisIn this experiment,lactate was added to the diet to investigate the alleviation effect of lactate on intestinal inflammatory damage of DSS-induced colitis piglets,and the effect of lactate on nutrient digestibility and growth performance of colitis piglets.The experiment selected 60 weaned DLY sows at 21 days of age with good health and similar body weight.According to the principle of similar body weight,they were divided into 3 treatments,namely control group(basal diet),DSS group(basic diet + DSS gavage)and lactate group(DSS gavage + 2% lactate diet).There were 10 replicates per treatment,with two piglets per replicate.After the experimental diet was fed for 7 days,the piglets in the DSS group and the lactate group were gavaged with 5% DSS solution for 4 consecutive days,and the control group was gavaged with the same volume of normal saline.On the morning of the 12 th day of the experiment,one piglet was weighed and slaughtered for each replicate,and intestinal tissue mucosal samples and chyme samples were collected.The remaining piglet in each replicate continued to feed for 21 days and collected growth performance data,and collected fecal samples on the last four days of the experiment to investigate the digestibility of feed nutrients.The results showed that:1)Compared with the control group,DSS induction significantly increased the diarrhea rate,fecal occult blood index and disease activity index of piglets(P < 0.05).The diarrhea rate,fecal occult blood index and disease activity index(P < 0.05)of piglets with colitis reduced the bleeding of colonic mucosa and the damage to intestinal structure caused by colitis.2)Compared with the control group,DSS induction significantly decreased the level of colonic mucosal lactate(P < 0.05);compared with the DSS group,dietary lactate supplementation could significantly increase the level of colonic mucosal lactate(P < 0.05).3)Compared with the control group,DSS induction significantly improved the activity of myeloperoxidase(MPO)in the colonic mucosa of piglets(P < 0.05);)Interferon gamma(IFN-γ)level(P < 0.05);The addition of lactate to the diet can significantly reduce the activity of MPO in the colon mucosa of piglets(P < 0.05);significantly reduce the levels of IL-1β and IL-18 in the colon mucosa of piglets(P < 0.05);significantly increase the CD206+content in the colon of piglets.4)Compared with the control group,DSS significantly increased the level of YAP in the colon mucosa of piglets(P < 0.05);significantly increased the m RNA levels of interleukin 12(IL-12)and nitric oxide synthase(i NOS)in the colon of piglets(P < 0.05).,significantly decreased the m RNA level of c AMP-regulated protein response element(CREM)(P < 0.05).Compared with the DSS group,lactate significantly increased the levels of GPR81 and GNB1 in the colon of piglets,and significantly decreased the level of YAP in the colon mucosa of piglets(P < 0.05);significantly decreased the m RNA levels of IL-12 and i NOS in the colon of piglets(P < 0.05).,significantly increased the m RNA level of arginase 1(Arg1)(P < 0.05);the m RNA level of c AMP-regulated protein response element(CREM)had a tendency to increase(P = 0.056).5)Compared with the control group,the serum MDA content of the piglets in the DSS group was significantly increased(P < 0.05),and the T-AOC activity was significantly decreased(P < 0.05).Compared with the DSS group,the serum MDA content of the piglets in the lactate group was significantly lower(P < 0.05).Compared with the control group,the contents of MDA and 8OHd G in the colon mucosa of piglets in the DSS group were significantly increased(P < 0.05),and the activities of T-AOC and GR were significantly decreased(P < 0.05).Compared with the DSS group,the MDA content in the colonic mucosa of the lactate group was significantly decreased(P < 0.05),and the activities of T-AOC and GR were significantly increased(P < 0.05).6)Compared with the control group,the numbers of total bacteria,lactobacilli,and bacillus in the colonic digesta of the DSS group piglets were significantly decreased(P < 0.05),and the number of Escherichia coli was significantly increased(P < 0.05).Compared with the DSS group,the numbers of total bacteria,lactobacilli and bifidobacteria in the colonic chyme of the piglets in the lactate group were significantly increased(P < 0.05).7)Compared with the control group,the content of isovaleric acid in the colonic digesta of piglets in the DSS group was significantly increased(P < 0.05).Compared with the DSS group,lactate significantly increased the content of butyric acid,isovaleric acid,and valeric acid in the colonic digesta of colitis piglets(P < 0.05).8)During the recovery period of colitis induced by DSS,compared with piglets in the control group,the average feed intake and average daily gain of piglets in the DSS group from 12 to 32 days were significantly decreased(P < 0.05),and the body weight of the piglets at 32 days of the experiment was significantly decreased(P <0.05).),the F/G ratio was significantly increased(P < 0.05);the digestibility of crude ash and calcium in the diet was significantly decreased(P < 0.05).Compared with the DSS group,the average daily feed intake of the piglets in the lactate group increased significantly from 12 to 32 days(P < 0.05),and the average daily gain had a tendency to increase(P = 0.085).trend(P = 0.055);lactate significantly improved the digestibility of dry matter,crude ash and calcium in the diet in colitis piglets(P < 0.05).9)After DSS induction,after 21 d feeding test,compared with the control group,DSS-induced colitis significantly increased the contents of MDA,TNF-α,IFN-γ,IL-18 and IL-1β in the serum of piglets(P < 0.05),decreased serum SOD activity(P <0.05).Compared with the DSS group,the addition of lactate to the diet significantly decreased the content of TNF-α in the serum of piglets(P < 0.05),and significantly increased the activity of T-AOC and SOD in the serum of piglets(P < 0.05).The results of this experiment showed that adding lactate to the diet could significantly increase the content of lactate in the colon during the inflammatory period and reduce the intestinal inflammatory injury caused by colitis.Further studies have shown that adding lactate to the diet can reduce the levels of IL-1β and IL-18 in the colonic mucosa by activating GPR81-related immune regulatory pathways in piglets with colitis,and increase the levels of anti-inflammatory cytokines in the colon;improve the intestinal ecological balance of microflora of piglets with colitis;increase the content of butyric acid in colonic chyme;relieve the oxidative stress of piglets during the period of inflammation,and improve the damage to the antioxidant capacity of piglets caused by colitis.Lactate supplementation in the diet can improve the digestibility of dry matter and calcium in the feed,and improve the growth retardation of piglets caused by the colitis caused by DSS.In summary:1)In the process of DSS-induced colonic inflammation in piglets,the content of lactate in the colonic mucosa of piglets first decreased and then gradually accumulated,and the accumulated lactate could activate the intestinal negative feedback regulation mechanism to regulate inflammation.2)Lactate supplementation in the diet can compensate for the decreased lactate content in the colonic mucosa of piglets caused by DSS-induced colitis,thereby activating the GPR81-related immune regulation pathway,reducing the levels of IL-1β and IL-18 in the colonic mucosa,and increasing the levels of colonic antiinflammatory cytokines.improve the intestinal microecological balance of piglets with colitis and increase the content of butyric acid in the colon;relieve the oxidative stress of piglets during the period of inflammation,and improve the damage to the antioxidant capacity of piglets caused by colitis;thereby alleviating DSS-induced colitis resulting in stunted growth of piglets.