A Research Overview on Arachidonic Acid:Fermentation Regulation and Purification

Arachidonic acid （ARA or AA）, one of the most important polyunsaturated fatty acids （PUFAs）, has various physiological activities and positive effects on human health. ARA production by Mortierella alpina has become a hot topic in recent years, owing to that it is effective, safe and easy to control. How to improve ARA yield and purification efficiency is important to ARA production in M. alpina. Therefore, in this review, we summarized some methods to improve ARA yield： optimization of culture conditions, mycelium aging technologies and metabolic regulation, and the commonly used methods for ARA isolation and purification, to provide a theoretical basis for ARA production by M. alpina fermentation.

Hepatitis B virus X protein promotes liver cell proliferation via a positive cascade loop involving arachidonic acid metabolism and p-ERK1/2

Hepatitis B virus X protein （HBx） plays a crucial role in the development of hepatocellular carcinoma. Here, we sought to identify the mechanisms by which HBx mediates liver cell proliferation. We found that HBx upregulated the levels of cyclooxygenase-2 （COX-2）, 5-1ipoxygenase （5-LOX） and phosphorylated extracellular signal-regulated protein kinases 1/2 （p-ERK1/2） in liver cells. HBx-induced p-ERK1/2 was abolished by inhibition of Gi/o proteins, COX or LOX. In addition, HBx increased the amounts of prostaglandin E2 （PGE2） and leukotriene B4 （LTB4） released from cell lines derived from hepatocytes. Moreover, these released arachidonic acid metabolites were able to activate ERK1/2. Interestingly, activated ERK1/2 could upregulate the expression of COX-2 and 5-LOX in a positive feedback manner. In conclusion, HBx enhances and maintains liver cell proliferation via a positive feedback loop involving COX-2, 5-LOX, released arachidonic acid metabolites, Gi/o proteins and p-ERK1/2.

FATTY ACIDS PROFILE IN A HIGH CELL DENSITY CULTURE OF ARACHIDONIC ACID-RICH PARIETOCHLORIS INCISA (TREBOUXIOPHYCEAE,CHLOROPHYTA) EXPOSED TO HIGH PFD

The changes in arachidonic acid (AA) and fatty acids profiles along the growth curve of Parietochloris incisa, a coccoid snow green alga, were studied in a 2.8 cm light-path flat photobioreactor, exposed to strong photon flux density [PFD, 2400 μEmol/(m 2·s)]. Sixteen fatty acids were identified by gas chromatography showing that AA was the dominant fatty acid (33%-41%) followed by linoleic acid (17%-21%). AA content was closely investigated with respect to total fatty acids (TFA), ash free dry weight (AFDW) of cell mass as well as total culture content. These parameters were influenced significantly in a similar manner by culture growth phase, i.e., slightly decreasing in the lag period, gradually increasing in the logarithmic phase, becoming maximal at the early stationary phase, starting to decrease at the late stationary phase, sharply dropping at the decline phase. The increase in AA per culture volume during the logarithmic phase was not only associated with the increase in AFDW but also connected with a corresponding increase in AA/TFA, TFA/AFDW as well as AA/AFDW. The sharp decrease in AA content of the culture during the decline phase was mainly due to the decrease in AA/TFA, TFA/AFDW and AA/AFDW, although AFDW declined only a small extent. Maximal AA concentration, obtained at the early stationary phase, was 900 mg/L culture volume, and the average daily net increase of AA during 9 days logarithmic growth was 1.7 g/(m 2·day). Therefore, harvesting prior to the decline phase in a batch culture, or at steady state in continuous culture mode seems best for high AA production. The latter possibility was also further confirmed by continuous culture with 5 gradients of harvesting rate.

PHYSIOLOGICAL INHIBITORY EFFECT OF OCS IN ARACHIDONIC ACID-RICH PARIETOCHLORIS INCISA (TREBOUXIOPHYCEAE, CHLOROPHYTA)

Parietochloris incisa is an arachidonic acid rich snow green alga. The main physiological profiles, such as ash free dry weight (AFDW), chlorophyll, carotenoid, protein and total fatty acids (TFA), in this alga exposed to old culture supernatant (OCS) at the decline phase or its crude ethyl acetate extracts (CEAE) were investigated by using tubular photobioreactors of different diameters. Results showed that both OCS and CEAE had strong inhibitory effect on the above physiological parameters. The longer the culture was exposed to OCS and the more CEAE were added into the algal culture, the more the above physiological properties were inhibited. Arachidonic acid (AA), the dominant component of fatty acids in this alga, was also seriously inhibited with respect to total TFA, AFDW of cell mass, or culture volume, due to a probable reduction of enzymes activities catalyzing chain elongation from C18:1ω9 to AA. These results incontestably evidenced that some CEAE dissolving substances existing in OCS, like auto inhibitors, inhibited P. incisa growth through feedback. Hence, any efficient removal of auto inhibitors from algal culture to decrease their bioactivity could be good for maximal production of desired products like AA.

Long-term modifications of blood pressure in normotensive and spontane-ously hypertensive rats by gene delivery of rAAV-mediated cytochrome P450 arachidonic acid hydroxylase

Arachidonic acid cytochrome P-450 （CYP） hydroxylase 4A isoforms, including 4A1, 4A2, 4A3 and 4A8 in the rat kidney, catalyze arachidonic acid to produce 19/20-Hydroxyeicosatetraenoic acids （20-HETE）, a biologically active metabolite, which plays an important role in the regulation of blood pressure. However, controversial results have been reported regarding the exact role of 20-HETE on blood pressure. In the present study, we used recombinant adenoassociated viral vector （rAAV） to deliver CYP 4A1 cDNA and antisense 4A1 cDNA into Sprague-Dawley （SD） rats and spontaneously hypertensive rats （SHR）, respectively, to investigate the effects of long-term modifications of blood pressure and the potential for gene therapy of hyperténsion. The mean systolic pressure increased by 14.2±2.5 mm Hg in rAAV.4A 1-treated SD rats and decreased by 13.7±2.2 mm Hg in rAAV.anti4A l-treated SHR rats 5 weeks after the injection compared with controls and these changes in blood pressure were maintained until the experiments ended at 24 weeks. In 4A1 treated animals CYP4A was overexpressed in various tissues, but preferentially in the kidney at both mRNA and protein levels. In anti-4Al-treated SHR, CYP4A mRNA in various tissues was probed, especially in kidneys, but 4A l protein expression was almost completely inhibited. These results suggest that arachidonic acid CYP hydroxylases contribute not only to the maintenance of normal blood pressure but also to the development of hypertension. rAAV-mediated anti4A administration strategy has the potential to be used as targeted gene therapy in human hypertension by blocking expression of CYP 4A in kidneys.

Docosahexaenoic acid suppresses arachidonic acid-induced proliferation of LS-174T human colon carcinoma cells

AIM： To investigate the impact of arachidonic acid （AA） and docosahexaenoic acid （DHA） and their combination on colon cancer cell growth. METHODS： The LS-174T colon cancer cell line was used to study the role of the prostaglandin precursor AA and the omega-3 polyunsaturated fatty acid DHA on cell growth. Cell viability was assessed in XTT assays. For analysis of cell cycle and cell death, flow cytometry and DAPI staining were applied. Expression of cyclooxygenase-2 （COX-2）, p21 and bcl-2 in ceils incubated with AA or DHA was examined by real-time RT-PCR. Prostaglandin E2 （PGE2） generation in the presence of AA and DHA was measured using a PGE2- ELISA. RESULTS： AA increased cell growth, whereas DHA reduced viability of LS 174T cells in a time- and dosedependent manner. Furthermore, DHA down- regulated mRNA of bcl-2 and up-regulated p21. Interestingly, DHA was able to suppress AA-induced cell proliferation and significantly lowered AA-derived PGE2 formation. DHA also down-regulated COX-2 expression. In addition to the effect on PGE2 formation, DHA directly reduced PGE2-induced cell proliferation in a dosedependent manner. CONCLUSION： These results suggest that DHA can inhibit the pro-proliferative effect of abundant AA or PGE2.

Enhancement of Arachidonic Acid Production by Mortierella isabellina Through Protoplast Regeneration Mutagenesis

A developed method was used for the enhancement of arachidonic acid production by M. isabellina. An orthogonal, rotatable and central composite design was applied to determine the optimum conditions for protoplast regeneration mutagenesis. The results showed that a commixture enzyme （cellulase and glusulase） at the concentration of 4%, enzymolysis temperature at 30℃ and enzymolysis time on 7.5 h were the optimal conditions, in which the lethality of M. isabellina spores was 78.4%. After mutagenesis and re-screenings, M. isabellina mutant Y-69 was obtained. GC analysis showed that the yield of arachidonic acid by Y-69 （2.92 g. L-1） was 3.56 times higher than that of the wild-type strain （0.82 g.L-1）. Pass generation tests showed that the properties of Y-69 by mutation were readily inherited.

Mutagenesis of Arachidonic Acid-producing Mortierella Isabellina and Analyses of Δ~6-desaturase Role by qPCR

Arachidonic acid （AA or ARA）, an essential to-6 polyunsaturated fatty acid （PUFA）, can be produced by Mortierella isabellina. Mutagenesis on Mortierella isabellina As3.3410 was induced to raise ARA production. The mutant strain of YZ-124 had the highest ARA of 4.72 g. L-1, which was 5.5 times higher than that of the original strain 3.3410. mRNA expression level of △ 6- desaturase was determined in five different kinds of ARA-producing Mortierella isabellina after cultured for 7 days, and in the mutant strain YZ-124 over a 3-8 day time-course. In addition, the desaturase activity and ARA content were measured at the selected time points. The lowest expression of △6-desaturase was observed in the original strain and the highest expression in the mutant strain YZ-124, which increased with increasing time in culture. Furthermore, a positive correlation was observed between the expression levels of △6-desaturase and ARA content. Based on this, △6-desaturase played a significant role in ARA synthesis pathway in Mortierella isabellina.

Involvement of Oxidative Stress and Down-Regulation of Bcl-2 in Arachidonic Acid-Induced Apoptosis in HUVECs

Human umbilical vein endothelial cells （HU VECs） were treated with arachidonic acid （AA）. After 24 h exposure to AA, typical morphological changes of apoptosis were observed by Giemsa stain and transmission electron microscopy. The apoptotic ratio in HUVECs treated with 50μmol/L, 100μmol/L and 150μmol/L AA were （20.7±3.6）%, （38.6±4.3）% and （52.5±7.5） % respectively. Contrarily, low concentration of AA （425μmol/L） exerted no influence on cell viability by MTT assay. Intracellular malondialdehyde increased significantly in a dose-dependent manner upon AA treatment and for the reduced glutathione. the opposite tendency was found Western Blots show that apoplosis triggered by AA was associated with the down-regulation of Bcl-2 expression, but not with Bax and p53. Pretreatment with 50μmol/L α-tocopherol reduced AA-induced oxidative stress and apoptosis, also inhibited the dowwregulation of Bcl-2/Bax ratio. These results suggested that high concentration of free AA could induce apoptosis in HUVECs probably via oxidative stress and down-regulation of Bcl-2.

A role for lipids as agents to alleviate stroke damage： the neuroprotective effect of 2-hydroxy arachidonic acid

Cerebrovascular accident（CVA）or stroke is one of the world＇s leading causes of death and permanent disability.The high social and medical costs associated with this pathology mean there is an urgent need to find effective therapies.Occlusion of the middle cerebral artery（MCAO）,mainly by clots,is the origin of most CVAs in humans.

Comprehensive analysis reveals an arachidonic acid metabolism-related gene signature in patients with pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma(PDAC)is highly heterogeneous,making its prognosis prediction difficult.The arachidonic acid(AA)cascade is involved in carcinogenesis.Therefore,the metabolic enzymes of the AA cascade consist of lipoxygenases(LOXs),phospholipase A2s(PLA2s),and cyclooxygenases(COXs)along with their metabolic products,including leukotrienes.Nevertheless,the prognostic potential of AA metabolism-associated PDAC has not been explored.Herein,the mRNA expression patterns and the matching clinical information of individuals with PDAC were abstracted from online data resources.We employed the LASSO Cox regression model to develop a multigene clinical signature in the TCGA queue.The GEO queue and the ICGC queue were employed as the validation queue.There was differential expression of a significant number of AA metabolism-associated genes(56.8%)between PDAC and neighboring nonmalignant tissues in the TCGA queue.Univariate Cox regression demonstrated that 13 of the differentially expressed genes(DEGs)were linked to overall survival(OS)(p<0.05).A 6-gene clinical signature was developed for stratifying the PDAC patients into two risk groups,with the high-risk group patients exhibiting remarkably lower OS than the low-risk group patients(p<0.001 in the TCGA data set and the ICGC queue,and p=0.001 in the GEO data set).The multivariate Cox data revealed the risk score as an independent OS predictor(HR>1,p<0.01).The receiver operating characteristic(ROC)curve verified the predictive potential of our signature.The expression and alteration of the six genes in PDAC were also validated using online databases.Functional analyses demonstrated that immune-linked cascades were enriched,and the immune status was remarkably different between the high-and low-risk groups.In summary,an AA metabolism-associated clinical gene signature can be applied for prognostic estimation in PDAC.

Effects of Total Saponins from Dioscorea Nipponica Makino on Monosodium Urate-Induced M1-Polarized Macrophages through Arachidonic Acid Signaling Pathway:An in vitro Study

Objective To investigate and reveal the underlying mechanism of the effect of total saponins from Dioscoreae nipponica Makino(TSDN)on the arachidonic acid pathway in monosodium urate(MSU)crystal-induced M1-polarized macrophages.Methods M1 polarization of RAW264.7 cells were induced by 1µg/mL lipopolysaccharide(LPS).The methylthiazolyldiphenyl-tetrazolium bromide method was then used to screen the concentration of TSDN.MSU(500µg/mL)was used to induce the gouty arthritis model.Afterwards,10µg/L TSDN and 8µmol/L celecoxib,which was used as a positive control,were added to the above LPS and MSU-induced cells for 24 h.The mRNA and protein expressions of cyclooxygenase(COX)2,5-lipoxygenase(5-LOX),microsomal prostaglandin E synthase derived eicosanoids(mPGES)-1,leukotriene B(LTB)4,cytochrome P450(CYP)4A,and prostaglandin E_(2)(PGE_(2))were tested by real-time polymerase chain reaction and Western blotting,respectively.The enzyme-linked immunosorbent assay was used to test the contents of M1 markers,including inducible nitric oxid synthase(NOS)2,CD80,and CD86.Results TSDN inhibited the proliferation of M1 macrophages and decreased both the mRNA and protein expressions of COX2,5-LOX,CYP4A,LTB4,and PGE_(2)(P<0.01)while increased the mRNA and protein expression of mPGES-1(P<0.05 or P<0.01).TSDN could also significantly decrease the contents of NOS2,CD80,and CD86(P<0.01).Conclusion TSDN has an anti-inflammation effect on gouty arthritis in an in vitro model by regulating arachidonic acid signaling pathway.

Adipose-derived stem cells inhibit dermal fibroblast growth and induce apoptosis in keloids through the arachidonic acid-derived cyclooxygenase-2/prostaglandin E2 cascade by paracrine

Background:The clinical features of keloids consist of aberrant proliferation,secretion,differentiation and apoptosis of keloid dermis-derived fibroblasts(KFBs).Notably,the apoptosis rate of KFBs is lower than the proliferation rate.Though the anti-fibrotic effect of adipose-derived stem cells(ADSCs)on keloids has become a hot topic of research,the exact anti-fibrotic mechanism of the paracrine effect remains unclear.This study aimed to find out how the conditioned medium of ADSCs(ADSC-CM)exerts an anti-fibrotic effect in KFBs.Methods:KFBs and ADSCs were extracted and cultured.Then,ADSC-CM was prepared.Whether ADSC-CM could inhibit KFB growth and induce apoptosis was verified by the use of a cell counting kit-8,an 5-Ethynyl-2-deoxyuridine(Edu)kit and flow cytometry.The expressions of cyclooxygenase-1(COX-1),COX-2,caspase 3 and B-cell lymphoma-2(Bcl-2)in ADSC-CM-cultured KFBs were tested by real-time PCR and western blotting.To clarify the role of COX-2 in ADSC-CM-induced KFB apoptosis,a specific COX-2 inhibitor,celecoxib,was applied to KFBs cultured in ADSC-CM.Moreover,we tested the production of arachidonic acid(AA)and prostaglandin E2(PGE2)by ELISA.Then,we established a keloid transplantation model in a nude mouse to validate the therapeutic effect in vivo.Results:The proliferation ability of KFBs cultured in ADSC-CM was found to be weakened and apoptosis was significantly increased.Caspase 3 expression was significantly upregulated and Bcl-2 was downregulated in ADSC-CM-cultured KFBs.Furthermore,ADSC-CM strikingly elevated COX-2 mRNA and protein expressions,but COX-1 expression was unaltered.COX-2 inhibitors reduced ADSC-CM-induced apoptosis.Additionally,COX-2 inhibition blocked the elevation of caspase 3 and reversed the decrease in Bcl-2 expression.ADSC-CM increased PGE2 levels by 1.5-fold and this effect was restrained by COX-2 inhibition.In the nude mouse model,expressions of AA,COX-2 and PGE2 were higher in the translated keloid tissues after ADSC-CM injection than in the controls.Conclusions:We showed activation of the COX-2/PGE2 cascade in KFBs in response to ADSC-CM.By employing a specific COX-2 inhibitor,COX-2/PGE2 cascade activation played a crucial role in mediating the ADSC-CM-induced KFB apoptosis and anti-proliferation effects.

Arachidonic acid Metabolism in Galactosamine／Endotoxin Indudced Acute Liver injury in Rats

The changes of the levels of LTC4, PGI2 and TXA2 in the liver tissue in SD rats with GaIN/LPS-induced acute liver injury was studied with radioimmunoassay (RIA). As a result,12h after the administration of GaIN/LPS, serum AST (398±37u), ALT (565 ±43u) increased (P<0.001 ) and the concentration of TXA2 (12188±588pg/g· w· wt) in liver tissue increased sigiuficantly(p<0.001), while the content of LTC4 (9713± 3557ng/g·w·wt ) and PGI2 (1748±560 pg/g· w·wt) in liver tissue were not obviously changed(p>0.05) and the inflammatory changes of the pathological findings were observed. The improvement of serum ALT (300±168u)(p< 0.05) and AST(273±424 u) (P<0. 05) and histopathological damage was observed after the administration of diethylcarbamazine (DEC), a LTA4 synthesis inhibitor, the liver TXA2(12740±699) concentration significantly increased (P<0. 001), while the levels of LTC4 (8179±1653) and PGI2 (2320±630) were not obviously changed. Serum ALT (536±74u) and AST (416± 41u)(P> 0. 05) levels and histopathology did not change with administration of indomethacin, a cyclooxygenase inhibitor, but the liver LTC4 (12166±13027) contents increased (P<0.05 ) and TXA2 (1868±791) reduced significantly (P<0. 001). The present study suggests that arachidonic acid metabolism in rats with acute liver injury are significantly abnormal. Leukotrienes and thromboxane are important inflammatory mediators in the liver injury.

Metabolic flux analysis on arachidonic acid fermentation

The analysis of flux distributions in metabolic networks has become an important approach for understand-ing the fermentation characteristics of the process.A model of metabolic flux analysis of arachidonic acid(AA)synthesis in Mortierella alpina ME-1 was established and carbon flux distributions were estimated in different fermentation phases with different concentrations of N-source.During the expo-nential,decelerating and stationary phase,carbon fluxes to AA were 3.28%,8.80%and 6.97%,respectively,with sufficient N-source broth based on the flux of glucose uptake,and those were increased to 3.95%,19.21%and 39.29%,respectively,by regulating the shifts of carbon fluxes via fermentation with limited N-source broth and adding 0.05% NaNO_(3) at 96 h.Eventually AA yield was increased from 1.3 to 3.5 g·L^(−1).These results suggest a way to improve AA fermentation,that is,fermentation with limited N-source broth and adding low concentration N-source during the stationary phase.

Inhibition of protein kinase B by Palmitate in the insulin signaling of HepG2 cells and the preventive effect of Arachidonic acid on insulin resistance

Elevated plasma levels of free fatty acids(FFAs)may contribute to insulin resistance(IR)that is characteristic of type 2 diabetes mellitus.In this study,we investigated the effects of two fatty acids,palmitate(PA)and arachidonic acid(AA)on glycogenesis under insulin signaling in HepG2cells,a transformed hepatic carcinoma cell line.In the presence of 200μmol of palmitate,insulin(10−7 mol/L)stimulation of glycogenesis was inhibited,as evidenced by increased glucose in the medium and decreased intracellular glycogen.Wortmannin(WM),a specific inhibitor of PI3K,dramatically decreased the amount of intracellular glycogen in cells without PA incubation.However,glycogen in PA treated cells was not significantly changed by WM,indicating that PA may also act on PI3K.Interestingly,AA restored the effects of WM inhibition on glycogenesis in PA cells.Western blot analysis demonstrated that PA in the absence of WM increased phosphorylated glycogen synthase(inactive form of GS)and decreased phosphorylated protein kinase B(active form of PKB),causing a reduction of intracellular glycogen.AA,however,reversed the effects of PA on GS and PKB.Furthermore,inhibition of protein kinase C(PKC)by a specific inhibitor chelerythrine chloride(CC)abolished the inhibitory effect of PA on glycogen synthesis by decreasing phosphorylated GS and increasing phosphorylated PKB.However,the effect of CC in the presence of PA disappeared when AA was also present.Our results suggest that there is a disruption of the insulin signaling pathway between PKB and GS when the cells were exposed to PA,contributing to IR.PA may also interrupt the PKC signaling pathway.In contrast,AA could rescue glycogenesis impaired by PA.

Synthesis of symmetrical medium-and long-chain triacylglycerols rich in arachidonic acid at sn-2 position for infant formula

Medium-and long-chain triacylglycerols(MLCT)rich in arachidonic acid(ARA)at sn-2 position were synthesized by a two-step enzymatic method.Firstly,sn-2 monoacylglycerols(MAG)were synthesized at a temperature of 25℃ by enzymatic alcoholysis.The MAG with 69.42%ARA at sn-2 position were obtained by solvent extraction and low temperature solvent crystallization.Secondly,the MLCT rich in ARA at sn-2 position and capric acid(CA)at sn-1,3 positions were produced by enzymatic esterification.Under the optimal conditions(MAG:CA=1:3(mol/mol),0.05 MPa vacuum,8% Lipozyme RM IM,5 h,25℃),the content of triacylglycerol was up to 93.60%.The triacylglycerol in the form of C10:0-C20:4-C10:0(including isomers)was about 40.43%.The ARA contents in the total and sn-2 fatty acid composition of the final product were 32.35%and 51.12%,respectively.MLCT rich in ARA at sn-2 position were successfully produced and the product has the potential application for functional food and infant formula.

The Property and Application of Arachidonic Acid

Arachidonic acid (AA) is one of the most important PUFAs (polyunsaturated fatty acids) in human body. A high-yield arachidonic acid-producing strain (mortierella alpina) was selected by ion implantation (the relative content of arachidonic acid is 70.2% among all fatty acids). This paper mainly introduced the structure, distribution, source, physiologic healthcare function and application of AA.

New insights into the interactions between the gut microbiota and the inflammatory response to ulcerative colitis in a mouse model of dextran sodium sulfate and possible mechanisms of action for treatment with PE&AFWE

Background:Inflammatory bowel disease(IBD),comprising Crohn's disease(CD)and ulcerative colitis(UC),is a heterogeneous state of chronic intestinal inflammation.Intestinal innate immunity,including innate immune cells,defends against pathogens and excessive entry of gut microbiota,while preserving immune tolerance to resident intestinal microbiota,and may be characterized by its capacity to produce a rapid and nonspecific reaction.The association between microbiota dysbiosis and the pathogenesis of IBD is complex and dynamic.When the intestinal ecosystem is in dysbiosis,the reduced abundance and diversity of intestinal gut microbiota make the host more vulnerable to the attack of exogenous and endogenous pathogenic gut microbiota.The aim of our study was to comprehensively assess the relationship between microbial populations within UC,the signaling pathways of pathogenic gut microbe therein and the inflammatory response,as well as to understand the effects of using PE&AFWE(poppy extract[Papaver nudicaule L.]and Artemisia frigida Willd.extract)on UC modulation.Methods:A UC mouse model was established by inducing SPF-grade C57BL/6 mice using dextrose sodium sulfate(DSS).Based on metagenomic sequencing to characterize the gut microbiome,the relationship between gut microbiota dysbiosis and gut microbiota was further studied using random forest and Bayesian network analysis methods,as well as histopathological analysis.Results:(1)We found that the 5 gut microbiota with the highest relative abundance of inflammatory bowel disease UC model gut microbiota were consistent with the top 5 ranked natural bacteria.There were three types of abundance changes in the model groups:increases(Chlamydiae/Proteobacteria and Deferribacteres),decreases(Firmicutes),and no significant changes(Bacteroidetes).The UC model group was significantly different from the control group,with 1308 differentially expressed species with abundance changes greater than or equal to 2-fold.(2)The proportion of the fecal flora in the UC group decreased by 37.5%in the Firmicutes and increased by 14.29%in the proportion of Proteobacteria compared to the control group before treatment.(3)The significantly enriched and increased signaling pathways screened were the'arachidonic acid metabolic pathway'and the'phagosomal pathway',which both showed a decreasing trend after drug administration.(4)Based on the causal relationship between different OTUs and the UC model/PE&AFWE administration,screening for directly relevant OTU networks,the UC group was found to directly affect OTU69,followed by a cascade of effects on OTU12,OTU121,OTU93,and OTU7,which may be the pathway of action that initiated the pathological changes in normal mice.(5)We identified a causal relationship between common differentially expressed OTUs and PE&AFWE and UC in the pre-and post-PE&AFWE-treated groups.Thereby,we learned that PE&AFWE can directly affect OTU90,after which it inhibits UC,inhibiting the activity of arachidonic acid metabolic pathway by affecting OTU118,which in turn inhibits the colonization of gut microbiota by OTU93 and OTU7.(6)Histopathological observation and scoring(HS)of the colon showed that there was a significant difference between the model group and the control group(p<0.001),and that there was a significant recovery in both the sulfasalazine(SASP)and the PE&AFWE groups after the administration of the drug(p<0.0001).Conclusion:We demonstrated causal effects and inflammatory metabolic pathways in gut microbiota dysbiosis and IBD,with five opportunistic pathogens directly contributing to IBD.PE&AFWE reduced the abundance of proteobacteria in the gut microbiota,and histopathology showed significant improvement.