The Correlation Of Candida Albicans Colonization With Serum Anti-Saccharomyces Cerevisiae Antibodies And Mannose-binding Lectin In Inflammatory Bowel Disease

Background and objectiveInflammatory bowel disease(IBD)is a group of chronic autoimmune diseases,which include ulcerative colitis(UC)and Crohn’s disease(CD).The causes of IBD are unclear,probably due to immune disorders.Recently,the number of IBD patients keeps on increasing in China.The bacterial intestinal microbiota plays major roles in human physiology and IBDs.In contrast to the enteric bacterial community,very little is known about the fungal microflora in inflammatory bowel disease.The colonization and species diversity of intestinal fungus in patients with IBD have increased,and the distribution of fungal has also changed,and there is a correlation between intestinal fungal and disease activity,suggesting that fungal play an important role in the occurrence and development of IBD.Candida albicans,as the fungal species with the highest colonization in the intestine,is increasingly gaining attention in IBD.Anti-Saccharomyces cerevisiae antibodies(ASCAs)are one of the serum markers of IBD and may also predict the development of IBD many years before the onset of the disease.Recently,Candida albicans was shown to express epitopes present in S.cerevisiae mannan,leading to ASCAs generation in both humans7 and in animals10.Mannose-binding lectin(MBL)is a pattern-recognition molecule of the innate immune system and may be involved in the pathogenesis of inflammatory bowel disease(IBD).Candida albicans colonization increased significantly in MBL-deficient mice8 and MBL deficiency is predominantly found in ASCAs-positive patients with IBD11.By detecting the serum level of ASCAs and MBL and Candida albicans colonization in IBD group and healthy control group,To explore the connection of ASCAs and MBL level in with the intestinal Candida albicans colonization.Methods103 IBD patients were enrolled,containing 42 UC patients and 61 CD patients.All the diagnosis met IBD diagnostic standard of the Chinese Medical Association meeting in Guangzhou.68 healthy volunteers were enrolled as healthy control.Clinical data of IBD patients include the Montrol phenotypes,disease activity and laboratory tests.The level of serum ASCAs were measured with enzyme-linked immunosorbent assay(ELISA).Relative proportion of Candida albicans in the faecal microbiota quantified using Real-time Quantitative PCR(qRT-PCR).Results1.The Candida albicans proportion was significantly increased in IBD compared with healthy controls(p<0.05),there was no difference between the IBD flare and IBD in remission(P>0.05).2.The proportion of Candida albicans was significantly higher in IBD patients with elevated IL-17 expression(P<0.05).3.Compared with healthy controls,the serum ASCAs titer was significantly higher in patients with Crohn’s disease(P<0.05),but there was no significant difference in the positive rate of ASCAs(P>0.05).ASCAs levels were not correlated with C.albicans proportion in all populations(P>0.05).4.There was no significant difference in MBL level,low expression rate and expression defect rate among IBD patients compared with healthy control group(P>0.05).Serum ASCAs titers were significantly higher in patients with MBL deficiency and low expression of inflammatory bowel disease(P<0.05).In CD patients,the Candida albicans proportion in MBL low expression individuals was higher than MBL normal expression individuals(P<0.05).There was no significant correlation between MBL expression and the proportion of Candida albicans in UC patients and healthy controls(P>0.05).ConclusionIBD patients are more heavily colonized by Candida albicans than controls.ASCAs level are not correlate with Candida albicans colonization in IBD.In CD patients,the Candida albicans proportion in MBL low expression individuals was higher than MBL normal expression individuals.The titers of ASCAs were significantly increased in MBL-deficient Patients.Possibly reflecting delayed clearance of oligomannan-containing microorganisms by the innate immune system in the MBL-deficient Patients.Mannan is an important component of Candida albicans cell wall,suggesting that Candida albicans plays an important role in the development of IBD and Th17-related immune responses.