Exploring Pathogenesis And Prognostic Biomarkers Of Primary Non-response To Infliximab When Treated Patients With Refractory Inflammatory Bowel Disease

Objective Inflammatory bowel disease(IBD),consist of ulcerative colitis(UC)and Crohn's disease(CD),is authorized as the nonspecific chronic inflammatory disease of the digestive tract.It no longer is a rare disease and only occurs in Western countries.Nowadays the incidence of IBD is rising in China.Besides,IBD is recognized as an abnormal inflammation caused by the interaction of genetic susceptibility,environmental factors and immune disorders.At the same time,it is referred to be a complicated pathophysiological process involving multiple genes and multiple factors,but its specific pathogenesis is still incompletely known and needs to be further explored.Consequently,IBD management be designed to regulate the abnormal immunity or inhibit the excessive inflammation,such as 5-aminosalicylic acid(5-ASA),corticosteroids,immunomodulatory agents and biological agents.These medicines are beneficial to induce remission and maintain of remission,especially infliximab(IFX).The introduction of IFX has completely changed the idea about the management of IBD.Because it can not only improve the IBD condition and improve the quality of life,but also allows to maintain remission without corticosteroids for a long time,which could reduce the incidence of hospitalization and colon surgery.However,35%to 58%of IBD patients occur primary non-response of IFX.Mounting evidences suggest that the lost of response associates with low trough serum of IFX and formation of anti-IFX antibody(ATI).In addition,lost of response of IFX is associated with a number of other factors,such as serum albumin and intestinal inflammation,which indicates it is a complex process.However,its mechanism has not been fully elucidated,and further exploration is needed.Method Weighted total Gene Network Analysis(WGCNA)was conducted on 5000 genes of 120 samples from GSE16879 of refractory IBD patients who characterized as primary non-response.The gene co-expression network was constructed when the soft threshold power was set to 6,which met a scale-free network distribution.Then module detection was performed and mapped the external information,namely"non-response before IFX of UC" group,“non-response after IFX of UC" group,"non-response before IFX of CD" group and "non-response after IFX of CD".The biological function of modules was analyzed by Gene Ontology and KEGG pathway.In addition,the hub genes of each module were screened,and their differential expression between whether or not IFX response was further analyzed.Results Six co-expressed modules,ranged in size from 180 to 1060 genes,were identified.Their biological functions involve mitochondrial respiratory electron transport chain,alcohol biosynthetic process,xenobiotic metabolic process,response to stress,small GTPase mediated signal transduction,and regulation of response to stimulus,etc.The correlations between modules and 4 groups of external clinical information were significant(P<0.01).Among them,"non-response before IFX of UC" group was significantly correlated with 3 modules(R2>0.39,P<0.001).Functional enrichment analysis found them to be related to mitochondrial respiratory electron transport chain,response to stress and regulation of response to stimulus.Three hub genes of EPB41L4B3,MSN and LY96 from related modules were screened.Compared to group of IFX response,EPB41L4B was down-expressed,and MSN and LY96 were up-expressed in the group of IFX non-response,respectively."non-response after IFX of UC" group was significantly correlated to one module(R2 = 0.27,P = 0.27).Functional enrichment analysis was found that it enriched several terms,such as xenobiotic metabolic process,cellular response to xenobiotic stimulus and monocarboxylic acid catabolic process.In addition,it is enriched in several pathways,namely metabolic pathways,peroxisome and fatty acid degradation.Compared to who have response to IFX,hub gene ACSL5 of this module was down-expressed in patients with refractory UC who have no response to IFX."non-response before IFX of CD" group were significantly correlated to the two modules(R2>0.20,P<0.02).Enrichment analysis found that they enrich in bicarbonate transport,alcohol biosynthetic process and regulation of response to stimulus,etc.The four hub genes of ESRP1,SATB2,MSN and LY96 were screened.Among them,ESRP1 and SATB2 were down-expressed,and MSN and LY96 were up-expressed in patients with refractory CD who have no response to IFX,respectively."non-response after IFX of CD" group was significantly correlated to one module(R2 = 0.26,P = 0.26).Enrichment analysis found that they enrich in bicarbonate transport,alcohol biosynthetic process and pattern specification process.It was also found in the signaling pathways of pathogenic Escherichia coli infection,protein processing in endoplasmic reticulum and bacterial invasion of epithelial cells.Hub genes of ESRP1,SATB2 and PRKACB were down-expressed in patients with refractory CD after IFX treatment in patients with refractory CD who have no response to IFX.Conclusion WGCNA was firstly performed to explore the pathogenesis and prognostic biomarkers of primary non-response to IFX when treated patients with refractory IBD.ACSL5 as the key gene is used to explore how adipocytokines,such as leptin,lead to IFX non-response in refractory UC patients.Similarly,ESRP1,SATB2 and PRKACB as the key genes were used to explore how pathogenic Escherichia coli caused IFX non-response in refractory CD patients.In addition,expression of EPB41L4B3,MSN,LY96,ESRP1 and SATB2 in colonic tissues could be used as prognostic biomarkers of primary non-response of IFX.Therefore,it provides an idea for subsequent study of IFX treating refractory IBD.