Recent advances in coeliac disease

Coeliac children on a gluten-free diet with or without oats display equal anti-avenin antibody titres

OBJECTIVE

Recent studies report negligible toxicity of oats in the majority of coeliac disease (CD) patients. It has previously been shown that children with untreated CD have circulating antibodies to oats avenin. In this study we performed serial assessments of anti-avenin antibodies in children under investigation for CD on a gluten-free diet with or without oats.

MATERIAL AND METHODS

The study involved 116 children, randomized to a standard gluten-free diet or a gluten-free diet supplemented with oats. Sera were obtained from 86 children, 48 in the standard gluten-free group and 38 in the gluten-free oats group, of which 33 consumed at least 10 g of oats daily. IgA and IgG anti-avenin antibodies were monitored at 0, 3, 6 and 12 months. Nitric oxide metabolites were measured in 7 patients, with deviating antibody results.

RESULTS

There was a significant decrease in anti-avenin antibodies in both groups at the end as compared to the beginning of the study, (p<0.001), but no difference was found between the two groups. IgA titres already declined after 3 months. IgG titres, although significantly decreased, remained high in the majority of patients in both groups. Nitric oxide levels were high in four of the analysed samples.

CONCLUSIONS

Oats per se, do not seem to produce a humoral immune reaction in children with CD when given in an otherwise gluten-free diet, indicating that the reaction requires gluten challenge. Anti-avenin antibodies were equal in the two study groups, and these findings strengthen the clinical impression that oats can be tolerated by the majority of patients with CD.

Anti-endomysial antibody of IgG1 isotype detection strongly increases the prevalence of coeliac disease in patients affected by type I diabetes mellitus

A strong association between type 1 insulin-dependent diabetes mellitus (IDDM1) and coeliac disease (CD) is well documented, but it is known that prevalence values are underestimated. Serum anti-endomysial antibodies (EMA), considered diagnostic for CD because of their high sensitivity and specificity, belong to the IgA class, but the existence of EMA of IgG1 isotype in the presence or absence of IgA deficiency was reported. In order to re-evaluate the occurrence of CD in IDDM1 patients we performed a screening in IDDM1 patients using EMA of both isotypes. Ninety-four adults affected by IDDM1 (unaffected by CD before enrolling) were enrolled and 83 blood donors as controls. All subjects were on a gluten-containing diet. Histology and biopsy culture were performed. EMA IgA and IgG1 in sera and culture supernatants were detected. Serum EMA were positive in 13 of 94 IDDM1 patients (13.8%). Six of 13 presented IgA-EMA, seven of 13 presented IgG1-EMA. No EMA were found in the control population. Total intestinal atrophy was found in all six patients with serum IgA-EMA and in five of seven with serum IgG1-EMA. Diagnosis of CD was confirmed by histology and organ culture in all 13 patients with serum EMA. The prevalence of CD in the patients affected by IDDM1 was 6.4% for IgA-EMA-positive and 7.4% for IgG1-EMA-positive patients. We confirmed the prevalence of CD in the IDDM1 population obtained with IgA-EMA screening only (6.4%). This prevalence value increases dramatically to 13.8% when IgG1-EMA are also used in the screening. We conclude that IgG1-EMA should also be sought whenever an IDDM1 patient undergoes screening for CD.

Are lower gastrointestinal investigations necessary in patients with coeliac disease?

BACKGROUND

Colonoscopy may be indicated in patients with coeliac disease who present with iron deficiency anaemia or in coeliac disease patients who have persisting diarrhoea despite being on a gluten-free diet. However, there are limited data to support this approach.

METHODS

We prospectively recruited patients who were found to have coeliac disease, having been referred with newly diagnosed iron deficiency anaemia. We also recruited a second group of patients with known coeliac disease. These patients had persisting diarrhoea despite being on a gluten-free diet for 6 months. All patients had colonoscopy and were matched with controls (without coeliac disease) who had similar indications for colonoscopy.

RESULTS

Ninety-eight consecutive new patients with coeliac disease and concurrent iron deficiency anaemia had colonoscopy performed. Twelve (12.2%) had pathology, three of which were carcinomas. This diagnostic yield was not significantly different from the findings in the control group 62/362 (17.1%) P=0.24. In coeliac disease patients with persisting diarrhoea (n=37), the diagnostic yield at colonoscopy was 1/37 (2.7%). This was significantly lower than our findings in the control group with chronic diarrhoea 55/390 (14%) P=0.05.

CONCLUSION

Colonoscopy should be considered in patients with coeliac disease (over the age of 45 years) who present with iron deficiency anaemia. Whilst, for coeliac disease patients with persisting diarrhoea (on a gluten-free diet) in the absence of sinister symptoms, a flexible sigmoidoscopy may be the initial investigation in order to exclude microscopic colitis. However, further larger prospective studies are required to evaluate this approach.