Luisa Mearin

The HLA-DQ2 gene dose effect in celiac disease is directly related to the magnitude and breadth of gluten-specific T cell responses

In patients with celiac disease, inflammatory T cell responses to HLA-DQ2-bound gluten peptides are thought to cause disease. Two types of HLA-DQ2 molecules exist, termed HLA-DQ2.5 and HLA-DQ2.2. Whereas HLA-DQ2.5 predisposes to celiac disease, HLA-DQ2.2 does not. We now provide evidence that the disease-associated HLA-DQ2.5 molecule presents a large repertoire of gluten peptides, whereas the non-disease-associated HLA-DQ2.2 molecule can present only a subset of these. Moreover, gluten presentation by HLA-DQ2 homozygous antigen-presenting cells was superior to presentation by HLA-DQ2/non-DQ2 heterozygous antigen-presenting cells in terms of T cell proliferation and cytokine secretion. Gluten presentation by HLA-DQ2.5/2.2 heterozygous antigen-presenting cells induced intermediate T cell stimulation. These results correlated with peptide binding to the antigen-presenting cells. Finally, we demonstrate that HLA-DQ trans dimers formed in HLA-DQ2.5/2.2 heterozygous individuals have properties identical with HLA-DQ2.5 dimers. Our findings explain the strongly increased risk of disease development for HLA-DQ2.5 homozygous and HLA-DQ2.2/2.5 heterozygous individuals, and they are indicative of a quantitative model for disease development, where HLA-DQ expression and the available number of T cell-stimulatory gluten peptides are critical limiting factors. This model may have important implications for disease prevention.

Fine mapping of the celiac disease-associated LPP locus reveals a potential functional variant

Using the Immunochip for genotyping, we identified 39 non-human leukocyte antigen (non-HLA) loci associated to celiac disease (CeD), an immune-mediated disease with a worldwide frequency of ∼1%. The most significant non-HLA signal mapped to the intronic region of 70 kb in the LPP gene. Our aim was to fine map and identify possible functional variants in the LPP locus. We performed a meta-analysis in a cohort of 25 169 individuals from six different populations previously genotyped using Immunochip. Imputation using data from the Genome of the Netherlands and 1000 Genomes projects, followed by meta-analysis, confirmed the strong association signal on the LPP locus (rs2030519, P = 1.79 × 10−49), without any novel associations. The conditional analysis on this top SNP-indicated association to a single common haplotype. By performing haplotype analyses in each population separately, as well as in a combined group of the four populations that reach the significant threshold after correction (P < 0.008), we narrowed down the CeD-associated region from 70 to 2.8 kb (P = 1.35 × 10−44). By intersecting regulatory data from the ENCODE project, we found a functional SNP, rs4686484 (P = 3.12 × 10−49), that maps to several B-cell enhancer elements and a highly conserved region. This SNP was also predicted to change the binding motif of the transcription factors IRF4, IRF11, Nkx2.7 and Nkx2.9, suggesting its role in transcriptional regulation. We later found significantly low levels of LPP mRNA in CeD biopsies compared with controls, thus our results suggest that rs4686484 is the functional variant in this locus, while LPP expression is decreased in CeD.

A toddler with recurrent oral and genital ulcers

In western countries, when a child presents with recurrent oral ulcers and colitis, the diagnosis of Crohn’s disease is mostly made. In our patient, the diagnosis was Behçet’s disease with gastrointestinal manifestations. Behçet’s disease with gastrointestinal manifestations has a similar clinical presentation to Crohn’s disease, but there is more organ involvement and the prognosis is more severe in the former. Because there is limited experience in the treatment of Behçet’s disease in the paediatric population, successful and unsuccessful treatment modalities in both paediatric and adult populations should be reported.

Efficacy of Home Telemonitoring versus Conventional Follow-up: A Randomized Controlled Trial among Teenagers with Inflammatory Bowel Disease

Background and Aims Conventional follow-up of teenagers with inflammatory bowel diseases [IBD] is done during scheduled outpatient visits regardless of how well the patient feels. We designed a telemonitoring strategy for early recognition of flares and compared its efficacy with conventional follow-up. Methods We used a multicentre randomized trial in patients aged 10-19 years with IBD in clinical remission at baseline. Participants assigned to telemonitoring received automated alerts to complete a symptom score and send a stool sample for measurement of calprotectin. This resulted in an individual prediction for flare with associated treatment advice and test interval. In conventional follow-up the health check interval was left to the physicians discretion. The primary endpoint was cumulative incidence of disease flares. Secondary endpoints were percentage of participants with a positive change in quality-of-life and cost-effectiveness of the intervention. Results We included 170 participants [84 telemonitoring; 86 conventional follow-up]. At 52 weeks the mean number of face-to-face visits was significantly lower in the telemonitoring group compared to conventional follow-up [3.6 vs 4.3, p < 0.001]. The incidence of flares [33 vs 34%, p = 0.93] and the proportion of participants reporting positive change in quality-of-life [54 vs 44%, p = 0.27] were similar. Mean annual cost-saving was €89 and increased to €360 in those compliant to the protocol. Conclusions Telemonitoring is as safe as conventional follow-up, and reduces outpatient visits and societal costs. The positive impact on quality-of-life was similar in the two groups. This strategy is attractive for teenagers and families, and health professionals may be interested in using it to keep teenagers who are well out of hospital and ease pressure on overstretched outpatient services. Trial registration NTR3759 [Netherlands Trial Registry].

Diagnostic Yield of Next-generation Sequencing in Very Early-onset Inflammatory Bowel Diseases: A Multicentre Study

Abstract Background and Aims An expanding number of monogenic defects have been identified as causative of severe forms of very early-onset inflammatory bowel diseases [VEO-IBD]. The present study aimed at defining how next-generation sequencing [NGS] methods can be used to improve identification of known molecular diagnosis and to adapt treatment. Methods A total of 207 children were recruited in 45 paediatric centres through an international collaborative network [ESPGHAN GENIUS working group] with a clinical presentation of severe VEO-IBD [n = 185] or an anamnesis suggestive of a monogenic disorder [n = 22]. Patients were divided at inclusion into three phenotypic subsets: predominantly small bowel inflammation, colitis with perianal lesions, and colitis only. Methods to obtain molecular diagnosis included functional tests followed by specific Sanger sequencing, custom-made targeted NGS, and in selected cases whole exome sequencing [WES] of parents-child trios. Genetic findings were validated clinically and/or functionally. Results Molecular diagnosis was achieved in 66/207 children [32%]: 61% with small bowel inflammation, 39% with colitis and perianal lesions, and 18% with colitis only. Targeted NGS pinpointed gene mutations causative of atypical presentations, and identified large exonic copy number variations previously missed by WES. Conclusions Our results lead us to propose an optimised diagnostic strategy to identify known monogenic causes of severe IBD.

Coeliac Disease in Subfertile Couples in the Netherlands

Background: Subfertility has been assumed as a long-term complication of unrecognized and/or untreated coeliac disease (CD). No data exist on the association between subfertility and CD in The Netherlands. Aims: To determine; 1.) the prevalence of (un)recognized CD in subfertile male-female couples in the Netherlands; 2.) if routine antibody screening for CD should be performed in patients visiting a fertility clinic. Methods: Subjects included 1038 male-female couples (n=2076) who visited the fertility clinic of the Leiden University Medical Centre in the Netherlands, between 2003-2009. All patients were serological screened, and unrecognized CD was defined in cases with simultaneous positive test results for antibodies against anti-tissue transglutaminase and endomysium. Clinical data was collected; gender, age, height, weight and diagnosis of subfertility. All patients were anonymized. The prevalence of unrecognised CD was compared to the one in the general adult population in the Netherlands (0.35%) (1) Results: The prevalence of unrecognized CD in subfertile male-female couples was 0.48% (10/2076), 0.3% female and 0.4% male (p=NS). In 1.5% of the women with an ovulation disorder CD was diagnosed (p=0.04). Compared to the control group, similar CD prevalences were found within the other subfertility categories unexplained subfertility, tuba pathology and androgenic disorder (p=NS). Conclusion: In our well-powered study cohort of subfertile male-female couples, the prevalence of unrecognized CD is comparable to the general population in the Netherlands. Unrecognized CD was 5 times more often detected in women with ovulation disorder compared to the control group, which suggest a possible association between CD and subfertility in females. No association was found in subfertile men and couples with unexplained subfertility. We would suggest performing serological screening for CD in females who are visiting the fertility clinic in the Netherlands.