Anti-microbial antibodies in celiac disease: Trick or treat?

Coincidence of antibodies against Hwp1 and ASCA, two distinct molecular targets of Candida albicans, reinforces the link between this fungal species and coeliac disease

Candida albicans is an immunogen for anti-Saccharomyces cerevisiae antibodies (ASCA), a serological marker of Crohn's disease. ASCA has also been reported in other autoimmune diseases, including coeliac disease (CeD). A strong antibody response against Hwp1, a protein associated with invasive hyphal form of C. albicans which presents peptide sequence homologies with gliadin, has also been described in CeD. This observation supports the hypothesis that C. albicans hyphal transition in C. albicans may trigger CeD onset through a mechanism of molecular/antigenic mimicry. In this study, we assessed whether the anti-C. albicans oligomannose and anti-Hwp1 protein responses may be linked despite their different pathophysiological significance. The measurement of ASCA levels in a cohort of patients involved in our previous Hwp1 study showed a significant correlation between the two biomarkers. This new observation further reinforces the link between C. albicans and CeD.

Prognostic tools for identification of high risk in people with Crohn's disease: systematic review and cost-effectiveness study

BACKGROUND

Crohn's disease is a lifelong condition that can affect any segment of the gastrointestinal tract. Some people with Crohn's disease may be at higher risk of following a severe course of disease than others and being able to identify the level of risk a patient has could lead to personalised management.

OBJECTIVE

To assess the prognostic test accuracy, clinical impact and cost-effectiveness of two tools for the stratification of people with a diagnosis of Crohn's disease by risk of following a severe course of disease.

DATA SOURCES

The data sources MEDLINE, EMBASE, the Cochrane Database of Systematic Reviews and the Cochrane Central Register of Controlled Trials were searched to inform the systematic reviews on prognostic accuracy, clinical impact of the prognostic tools, and economic evaluations. Additional data sources to inform the review of economic evaluations were NHS Economic Evaluation Database, Database of Abstracts of Reviews of Effects and the Health Technology Assessment Database.

REVIEW METHODS

Systematic reviews of electronic databases were carried out from inception to June 2019 for studies assessing the prognostic accuracy and clinical impact of the IBDX® (Crohn's disease Prognosis Test; Glycominds Ltd, Lod, Israel) biomarker stratification tool and the PredictSURE-IBD™ (PredictImmune Ltd, Cambridge, UK) tool. Systematic reviews of studies reporting on the cost-effectiveness of treatments for Crohn's disease were run from inception to July 2019. Two reviewers independently agreed on studies for inclusion, assessed the quality of included studies and validated the data extracted from studies. Clinical and methodological heterogeneity across studies precluded the synthesis of data for prognostic accuracy. A de novo economic model was developed to compare the costs and consequences of two treatment approaches - the 'top-down' and 'step-up' strategies, with step-up considered standard care - in people at high risk of following a severe course of Crohn's disease. The model comprised a decision tree and a Markov cohort model.

RESULTS

Sixteen publications, including eight original studies (n = 1478), were deemed relevant to the review of prognostic accuracy. Documents supplied by the companies marketing the prognostic tools were also reviewed. No study meeting the eligibility criteria reported on the sensitivity or specificity of the IBDX biomarker stratification tool, whereas one study provided estimates of sensitivity, specificity and negative predictive value for the PredictSURE-IBD tool. All identified studies were observational and were considered to provide weak evidence on the effectiveness of the tools. Owing to the paucity of data on the two tools, in the base-case analysis the accuracy of PredictSURE-IBD was assumed to be 100%. Accuracy of IBDX was assumed to be 100% in a scenario analysis, with the cost of the tests being the only difference between the analyses. The incremental analysis of cost-effectiveness demonstrated that top-down (via the use of PredictSURE-IBD in the model) is more expensive and generates fewer quality-adjusted life-years than step-up (via the standard care arm of the model).

LIMITATIONS

Despite extensive systematic searches of the literature, no robust evidence was identified of the prognostic accuracy of the biomarker stratification tools IBDX and PredictSURE-IBD.

CONCLUSIONS

Although the model indicates that standard care dominates the tests, the lack of evidence of prognostic accuracy of the two tests and the uncertainty around the benefits of the top-down and step-up treatment approaches mean that the results should be interpreted as indicative rather than definitive.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42019138737.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Evidence Synthesis programme and will be published in full in Health Technology Assessment; Vol. 25, No. 23. See the NIHR Journals Library website for further project information.

Candida albicans in celiac disease: A wolf in sheep's clothing

Candida albicans is a commensal fungus with a potential pathogenicity and celiac disease is an autoimmune condition. Both share multiple pathophysiological junctions, including serological markers against cell-wall proteins of Candida, anti-gliadin antibodies are positive in both entities, gluten and a candidal virulence factor share sequence similarity and the autoantigen of celiac disease, the tissue transglutaminase, is pivotal in Candida albicans commensalism and hostile behavior and its covalently cross linked products are stable and resistant to breakdown in the two entities. Those autoimmune/infectious cross roads are the basis for the hypothesis that Candida albicans is an additional environmental factor for celiac disease autoimmunogenesis.

Humoral immunity links Candida albicans infection and celiac disease

Objective

The protein Hwp1, expressed on the pathogenic phase of Candida albicans, presents sequence analogy with the gluten protein gliadin and is also a substrate for transglutaminase. This had led to the suggestion that C. albicans infection (CI) may be a triggering factor for Celiac disease (CeD) onset. We investigated cross-immune reactivity between CeD and CI.

Methods

Serum IgG levels against recombinant Hwp1 and serological markers of CeD were measured in 87 CeD patients, 41 CI patients, and 98 healthy controls (HC). IgA and IgG were also measured in 20 individuals from each of these groups using microchips sensitized with 38 peptides designed from the N-terminal of Hwp1.

Results

CI and CeD patients had higher levels of anti-Hwp1 (p=0.0005 and p=0.004) and anti-gliadin (p=0.002 and p=0.0009) antibodies than HC but there was no significant difference between CeD and CI patients. CeD and CI patients had higher levels of anti-transglutaminase IgA than HC (p=0.0001 and p=0.0039). During CI, the increase in anti-Hwp1 paralleled the increase in anti-gliadin antibodies. Microchip analysis showed that CeD patients were more reactive against some Hwp1 peptides than CI patients, and that some deamidated peptides were more reactive than their native analogs. Binding of IgG from CeD patients to Hwp1 peptides was inhibited by γIII gliadin peptides.

Conclusions

Humoral cross-reactivity between Hwp1 and gliadin was observed during CeD and CI. Increased reactivity to Hwp1 deamidated peptide suggests that transglutaminase is involved in this interplay. These results support the hypothesis that CI may trigger CeD onset in genetically-susceptible individuals.

New serological markers in pediatric patients with inflammatory bowel disease

The spectrum of serological markers associated with inflammatory bowel disease (IBD) is rapidly growing. Due to frequently delayed or missed diagnoses, the application of non-invasive diagnostic tests for IBD, as well as differentiation between ulcerative colitis (UC) and Crohn's disease (CD), would be useful in the pediatric population. In addition, the combination of pancreatic autoantibodies and antibodies against Saccharomyces cerevisiae antibodies/perinuclear cytoplasmic antibody (pANCA) improved the sensitivity of serological markers in pediatric patients with CD and UC. Some studies suggested that age-associated differences in the patterns of antibodies may be present, particularly in the youngest children. In CD, most patients develop stricturing or perforating complications, and a significant number of patients undergo surgery during the disease course. Based on recent knowledge, serum antibodies are qualitatively and quantitatively associated with complicated CD behavior and CD-related surgery. Pediatric UC is characterized by extensive colitis and a high rate of colectomy. In patients with UC, high levels of anti-CBir1 and pANCA are associated with the development of pouchitis after ileal pouch-anal anastomosis. Thus, serologic markers for IBD can be applied to stratify IBD patients into more homogeneous subgroups with respect to disease progression. In conclusion, identification of patients at an increased risk of rapid disease progression is of great interest, as the application of early and more aggressive pharmaceutical intervention could have the potential to alter the natural history of IBD, and reduce complications and hospitalizations.

Recommendations for identifying Crohn's disease patients with poor prognosis

Clinical presentation at diagnosis and the disease course of Crohn's disease is heterogeneous and variable over time. The majority of patients with Crohn's disease will develop at least one stricturing or perforating complication requiring surgery during follow-up. New data support a change in the natural history of the disease associated with the advent of biologicals and tailored treatment strategy. Therefore, it is important to identify patients at risk for disease progression as soon as possible. In recent years, much emphasis has been placed on determining important predictive factors. Complex evaluation of factors such as clinical and endoscopic presentation, fecal, serological and routine laboratory tests, and genetic factors is needed. This review summarizes the available evidence and will hopefully assist clinicians when choosing a treatment strategy in everyday practice.

Tumor-associated glycans and their role in gynecological cancers: accelerating translational research by novel high-throughput approaches

Glycans are important partners in many biological processes, including carcinogenesis. The rapidly developing field of functional glycomics becomes one of the frontiers of biology and biomedicine. Aberrant glycosylation of proteins and lipids occurs commonly during malignant transformation and leads to the expression of specific tumor-associated glycans. The appearance of aberrant glycans on carcinoma cells is typically associated with grade, invasion, metastasis and overall poor prognosis. Cancer-associated carbohydrates are mostly located on the surface of cancer cells and are therefore potential diagnostic biomarkers. Currently, there is increasing interest in cancer-associated aberrant glycosylation, with growing numbers of characteristic cancer targets being detected every day. Breast and ovarian cancer are the most common and lethal malignancies in women, respectively, and potential glycan biomarkers hold promise for early detection and targeted therapies. However, the acceleration of research and comprehensive multi-target investigation of cancer-specific glycans could only be successfully achieved with the help of a combination of novel high-throughput glycomic approaches.

Microbial translocation across the GI tract

The lumen of the gastrointestinal (GI) tract is home to an enormous quantity of different bacterial species, our microbiota, that thrive in an often symbiotic relationship with the host. Given that the healthy host must regulate contact between the microbiota and its immune system to avoid overwhelming systemic immune activation, humans have evolved several mechanisms to attenuate systemic microbial translocation (MT) and its consequences. However, several diseases are associated with the failure of one or more of these mechanisms, with consequent immune activation and deleterious effects on health. Here, we discuss the mechanisms underlying MT, diseases associated with MT, and therapeutic interventions that aim to decrease it.

The impact of intestinal resection on serum levels of anti-Saccharomyces cerevisiae antibodies (ASCA) in patients with Crohn's disease

BACKGROUND

Antibodies to Saccharomyces cerevisiae (ASCA) are highly prevalent in sera of patients with Crohn's disease and have been proposed to identify subgroups of patients with a disabling disease course.

AIM

To investigate the impact of intestinal resection on serum levels of ASCA in patients with Crohn's disease and the predictive value of ASCA levels on surgical recurrence.

METHODS

Sera from 60 patients who underwent 'curative' intestinal resection due to stricturing and/or penetrating complications were collected preoperatively and during post-operative follow-up (week 2, months 4, 8 and 11 ± 1). Measurement of ASCA IgG and IgA isotypes were performed using ELISA. Re-operation rate was associated with ASCA status and serum levels.

RESULTS

At baseline 44/60 (73%) of patients were rated as positive for ASCA IgG, 45/60 (75%) for ASCA IgA and 52/60 (87%) as positive for at least one of both. ASCA serum levels remained stable during first year from resection. After a median of 106 months 10 of 40 (25%) patients with long-term follow-up underwent one or more intestinal re-operations. Neither ASCA positivity nor absolute ASCA serum levels were predictive of surgical recurrence.

CONCLUSIONS

Serum ASCA levels remain stable after curative intestinal resection in Crohn's disease. This indicates the persistence of both stimulus and immunological mechanism operative in the production of ASCA even after complete surgical resection of macroscopically inflamed intestinal tissue. After intestinal resection, neither ASCA positivity nor ASCA serum levels predict the risk of surgical recurrence during long-term follow-up.

Current and future role of serogenomics in ulcerative colitis

Ulcerative colitis (UC), a chronic inflammatory bowel disease, occurs in genetically susceptible individuals who mount inappropriate immune responses to endoluminal antigens. Serologic and genetic markers have shown great potential for clinical application in Crohn's disease (CD), particularly for prognostication. However, their use is not as well established in UC. The aim of this paper is to highlight the clinical relevance of these markers for diagnostics and prognostication in UC. This review identified studies that cited the use of serum and genetic biomarkers in UC when these biomarkers were used in diagnostic, prognostic, and therapeutic response prediction applications. Several serologic and genetic markers associated with UC were identified, and this review presents and summarizes these data, focusing on the biomarkers' established and emerging diagnostic and prognostic utility. Although more established in CD, the data provided by serologic and genetic testing in UC has the potential to enhance clinical decision making.

Results of the 2nd part Scientific Workshop of the ECCO. II: Measures and markers of prediction to achieve, detect, and monitor intestinal healing in inflammatory bowel disease

The healing of the intestine is becoming an important objective in the management of inflammatory bowel diseases. It is associated with improved disease outcome. Therefore the assessment of this healing both in clinical studies and routine practice is a key issue. Endoscopy for the colon and terminal ileum and computerized tomography or magnetic resonance imaging for the small bowel are the most direct ways to evaluate intestinal healing. However, there are many unsolved questions about the definition and the precise assessment of intestinal healing using these endoscopic and imaging techniques. Furthermore, these are relatively invasive and expensive procedures that may be inadequate for regular patients' monitoring. Therefore, biomarkers such as C-reactive protein and fecal calprotectin have been proposed as surrogate markers for intestinal healing. Nevertheless, the sensitivity and specificity of these markers for the prediction of healing may be insufficient for routine practice. New stool, blood or intestinal biomarkers are currently studied and may improve our ability to monitor intestinal healing in the future.

Nutritional influences in selected gastrointestinal diseases

Nutritional factors, as sources of luminal antigens, have been thought to be important factors in the immunopathogenesis of numerous gastrointestinal diseases. In some diseases, the role of the nutritional component is causal in the susceptible host. Such diseases include celiac disease, a common heritable chronic inflammatory condition of the small intestine induced by dietary wheat, rye and barley, in susceptible individuals. Specific HLA-DQ2 and HLA-DQ8 risk alleles are necessary, but not sufficient, for disease development. The well-defined role of HLA-DQ heterodimers encoded by these alleles is to present cereal peptides to CD4+ T cells, activating an inflammatory immune response in the intestine. Genome-wide association studies have been performed which identified the IL2-IL21 risk locus and other genes with immune functions and key roles in thymic T-cell selection. Another example for this group is Wilson's disease, an autosomal recessive disorder of copper metabolism caused by mutation of the ATP7B gene, resulting in a defect of biliary copper excretion and toxic accumulation in the body, especially in the liver, brain and cornea, resulting in hepatic and/or neurological symptoms. In other diseases, however, the association is less well established. In such endeavor, epidemiological observations may become a valuable part of the overall investigations aimed at identifying dietary factors, which are involved in the initiation and perpetuation of the specific disease. As an example, relationships between nutrition and colorectal cancer have been hypothesized early on (e.g. folate, calcium, vitamin D, red meat). Similarly, intake of certain diet constituents like fat, refined sugar, fruits, vegetables and fiber was reported to be associated with the expression of inflammatory bowel diseases. In addition, in children with active Crohn's disease, enteral nutrition was found to be equally effective as corticosteroids in induction of remission, with mucosal healing induced by downregulation of mucosal pro-inflammatory cytokine profiles in both the ileum and the colon after enteral nutrition. However, the particular effect of the consumption of each type of food remains questionable in most cases, at least in part because of insufficient data and serious methodological limitations (e.g. recall bias, heterogeneity between collected data, lack of correction for covariates, difficulties in double blinding).

Serum lipopolysaccharide-binding protein and soluble CD14 are markers of disease activity in patients with Crohn's disease

BACKGROUND

In inflammatory bowel disease (IBD), enhanced inflammatory activity in the gut is thought to increase the risk of bacterial translocation and endotoxemia. In the present study we investigated the association between serum level of lipopolysaccharide-binding protein (LBP), soluble CD14 (sCD14), and clinical disease activity, high-sensitivity C-reactive protein (hs-CRP), antimicrobial serology profile, NOD2/CARD15 status, and clinical phenotype in a large cohort of Hungarian Crohn's disease (CD) patients.

METHODS

In all, 214 well-characterized, unrelated, consecutive CD patients (male/female ratio: 95/119; age: 35.6 ± 13.1 years; duration:8.3 ± 7.5 years) and 110 healthy controls were investigated. Sera were assayed for LBP, sCD14, hs-CRP, ASCA IgG/IgA, anti-OMP IgA, and pANCA antibodies. NOD2/CARD15 and TLR4 variants were tested. Detailed clinical phenotypes were determined by reviewing the patients' medical charts.

RESULTS

Serum LBP level was significantly higher (P < 0.0001 for both), while sCD14 was lower (P < 0.0001) in both active and inactive CD compared to the controls. The accuracy of hs-CRP (area under the curve [AUC] = 0.66), sCD14 (AUC = 0.70), and LBP (AUC = 0.58) was comparable for identifying patients with active disease. There was a significant correlation between LBP (P < 0.001), sCD14 (P = 0.015), and hs-CRP levels but not with antimicrobial seroreactivity or NOD2/CARD15 genotype. In inactive CD, LBP was associated with penetrating disease. In a Kaplan-Meier analysis and a proportional Cox-regression analysis, LBP (P = 0.006), sCD14 (P = 0.007), and previous relapse frequency (P = 0.023) were independently associated with time to clinical relapse during a 12-month follow-up period.

CONCLUSIONS

Serum LBP and sCD14 are markers of disease activity in CD with a similar accuracy as hs-CRP. In addition, LBP, sCD14, and a high frequency of previous relapses were independent predictors for 1-year clinical flare-up. (Inflamm Bowel Dis 2011).

Serologic antiglycan antibodies in inflammatory bowel disease

At diagnosis, the clinical presentation of both entities of inflammatory bowel disease (IBD), Crohn's disease (CD) and ulcerative colitis (UC), can be highly heterogeneous, leading to a delay in correct identification or differentiation between CD and UC in a subgroup of patients. In addition, the natural history of IBD patients is strikingly variable. During the life of a CD patient, in the majority of instances, stricturing or perforating complications occur, leading to surgery. Serologic antiglycan antibodies directed against various microbial carbohydrate epitopes are useful in differentiation of CD vs. UC and are a promising tool for identification of CD patients at risk for rapid progression and need for surgical intervention. Instruments for prediction of CD behavior are critical, as the use of immunomodulators and/or biologicals early in the disease course might be justified for patients with a high hazard for complicated disease behavior.

Presence of anti-microbial antibodies in liver cirrhosis--a tell-tale sign of compromised immunity?

BACKGROUND

Bacterial translocation plays important role in the complications of liver cirrhosis. Antibody formation against various microbial antigens is common in Crohn's disease and considered to be caused by sustained exposure to gut microflora constituents. We hypothesized that anti-microbial antibodies are present in patients with liver cirrhosis and may be associated with the development of bacterial infections.

METHODOLOGY/PRINCIPAL FINDINGS

Sera of 676 patients with various chronic liver diseases (autoimmune diseases: 266, viral hepatitis C: 124, and liver cirrhosis of different etiology: 286) and 100 controls were assayed for antibodies to Saccharomyces cerevisiae (ASCA) and to antigens derived from two intestinal bacterial isolates (one gram positive, one gram negative, neither is Escherichia coli). In patients with liver cirrhosis, we also prospectively recorded the development of severe episodes of bacterial infection. ASCA and anti-OMP Plus™ antibodies were present in 38.5% and 62.6% of patients with cirrhosis and in 16% and 20% of controls, respectively (p<0.001). Occurrence of these antibodies was more frequent in cases of advanced cirrhosis (according to Child-Pugh and MELD score; p<0.001) or in the presence of ascites (p<0.001). During the median follow-up of 425 days, 81 patients (28.3%) presented with severe bacterial infections. Anti-microbial antibody titers (p = 0.003), as well as multiple seroreactivity (p = 0.036), was associated with infectious events. In logistic regression analysis, the presence of ascites (OR: 1.62, 95%CI: 1.16-2.25), co-morbidities (OR: 2.22, 95%CI: 1.27-3.86), and ASCA positivity (OR: 1.59, 95%CI: 1.07-2.36) were independent risk factors for severe infections. A shorter time period until the first infection was associated with the presence of ASCA (p = 0.03) and multiple seropositivity (p = 0.037) by Kaplan-Meier analysis, and with Child-Pugh stage (p = 0.018, OR: 1.85) and co-morbidities (p<0.001, OR: 2.02) by Cox-regression analysis.

CONCLUSIONS/SIGNIFICANCE

The present study suggests that systemic reactivity to microbial components reflects compromised mucosal immunity in patients with liver cirrhosis, further supporting the possible role of bacterial translocation in the formation of anti-microbial antibodies.

Is the disease course predictable in inflammatory bowel diseases?

During the course of the disease, most patients with Crohn's disease (CD) may eventually develop a stricturing or a perforating complication, and a significant number of patients with both CD and ulcerative colitis will undergo surgery. In recent years, research has focused on the determination of factors important in the prediction of disease course in inflammatory bowel diseases to improve stratification of patients, identify individual patient profiles, including clinical, laboratory and molecular markers, which hopefully will allow physicians to choose the most appropriate management in terms of therapy and intensity of follow-up. This review summarizes the available evidence on clinical, endoscopic variables and biomarkers in the prediction of short and long-term outcome in patients with inflammatory bowel diseases.

Is the disease course predictable in inflammatory bowel diseases?

During the course of the disease, most patients with Crohn's disease (CD) may eventually develop a stricturing or a perforating complication, and a significant number of patients with both CD and ulcerative colitis will undergo surgery. In recent years, research has focused on the determination of factors important in the prediction of disease course in inflammatory bowel diseases to improve stratification of patients, identify individual patient profiles, including clinical, laboratory and molecular markers, which hopefully will allow physicians to choose the most appropriate management in terms of therapy and intensity of follow-up. This review summarizes the available evidence on clinical, endoscopic variables and biomarkers in the prediction of short and long-term outcome in patients with inflammatory bowel diseases.