Improved efficacy by using the pTnT-rhtTG plasmid for the detection of celiac disease specific tissue transglutaminase autoantibodies in radioligand binding assays

Longitudinal screening of HLA-risk and HLA-nonrisk children for celiac disease to age 15 years: CiPiS study

OBJECTIVES

Autoantibodies against tissue transglutaminase (tTG) are serological markers of celiac disease. The aim was to study the applicability of human leukocyte antigen (HLA)-genotyping and tTG autoantibodies in the screening of celiac disease in a longitudinal birth cohort followed to age 15 years.

METHODS

Included were 13,860 HLA-DQ-genotyped children at birth and previously invited to a screening at age 3 and 9 years, respectively. HLA-DQB1*02 and/or DQB1*03:02 (HLA-risk) children were compared with non-HLA-DQB1*02 and non-DQB1*03:02 (HLA-nonrisk) children. The present study reinvited 12,948/13,860 (93.4%) children at age 15 years of whom 1056/2374 (44.5%) participated in screening at both age 3 and 9 years. Both immunoglobulin A (IgA) and G (IgG) autoantibodies against tTG were analyzed separately in radiobinding assays. Persistently tTG autoantibody-positive children were examined with intestinal biopsy to confirm the diagnosis of celiac disease.

RESULTS

At age 3 years, celiac disease was diagnosed in 56/1635 (3.4%) HLA-risk children compared with 0/1824 HLA-nonrisk children (p < 0.001). By age 9 years, celiac disease was diagnosed in 72/1910 (3.8%) HLA-risk children compared with 0/2167 HLA-nonrisk children (p < 0.001). Screening at age 15 years detected 14/1071 (1.3%) HLA-risk children positive for IgA-tTG and/or IgG-tTG of whom 12/1071 (1.1%) remained persistently positive. Among those, 10/1071 (0.9%, 95% confidence interval: 0.4%-1.7%) HLA-risk children were diagnosed with celiac disease compared with 0/1303 HLA-nonrisk children (p < 0.001) and 5/491 (1.0%) were negative in screenings at both 3 and 9 years of age.

CONCLUSIONS

Screening for celiac disease needs to be performed at multiple timepoints to detect all cases but can be restricted to children at HLA-risk.

First trimester enterovirus IgM and beta cell autoantibodies in mothers to children affected by type 1 diabetes autoimmunity before 7 years of age

BACKGROUND

Autoimmune (type 1) diabetes (T1D) is a frequent chronic disease in children and adolescents globally. Gestational enterovirus (EV) infections have been associated with an increased risk for T1D in the offspring. We test the hypothesis that EV infections during the first trimester were associated with beta cell autoantibodies in mothers of children who developed islet autoantibodies before 7 years of age.

MATERIALS AND METHODS

Local registries were used to identify mothers to children born 2000-2007 who developed either beta cell autoantibodies or T1D during follow up. Serum samples from the first trimester were located in the Biobank. A total of 448 index mothers were identified and compared to 891 matched control mothers. EV-IgM was determined in a capture enzyme immunoassay. Beta cell autoantibodies were analyzed in standard radio binding assays.

RESULTS

The frequency of EV-IgM in index mothers was 20% (89/448), which did not differ from the control mothers 20% (175/891) (p = 0.922). Index mothers had multiple beta cell autoantibodies more often than control mothers (p = 0.037). Beta cell autoantibodies were increased during the November-April winter months in index compared to control mothers (p = 0.022). The observed difference was possibly explained by the months of February-April (p = 0.014). Concomitant EV-IgM and beta cell autoantibodies tended to be more common among index compared to control mothers (p = 0.039).

CONCLUSION

EV-IgM during the first trimester may be associated with beta cell autoantibodies in mothers to children who developed either beta cell autoantibodies or T1D before 7 years of age.

Osteoprotegerin autoantibodies do not predict low bone mineral density in middle-aged women

Purpose

Autoantibodies against osteoprotegerin (OPG) have been associated with osteoporosis. The aim was to develop an immunoassay for OPG autoantibodies and test their diagnostic usefulness of identifying women general population with low bone mineral density.

Methods

Included were 698 women at mean age 55.1 years (range 50.4–60.6) randomly selected from the general population. Measurement of wrist bone mineral density (g/cm²) was performed of the non-dominant wrist by dual-energy X-ray absorptiometry (DXA). A T-score < − 2.5 was defined as having a low bone mineral density. Measurements of OPG autoantibodies were carried by radiobinding assays. Cut-off levels for a positive value were determined from the deviation from normality in the distribution of 398 healthy blood donors representing the 99.7th percentile.

Results

Forty-five of the 698 (6.6%) women were IgG-OPG positive compared with 2 of 398 (0.5%) controls (p < 0.0001) and 35 of the 698 (5.0%) women had a T-score < − 2.5. There was no difference in bone mineral density between IgG-OPG positive (median 0.439 (range 0.315–0.547) g/cm²) women and IgG-OPG negative (median 0.435 (range 0.176–0.652) g/cm²) women (p = 0.3956). Furthermore, there was neither a correlation between IgG-OPG levels and bone mineral density (r_s = 0.1896; p = 0.2068) nor T-score (r_s = 0.1889; p = 0.2086). Diagnostic sensitivity and specificity of IgG-OPG for low bone mineral density were 5.7% and 92.9%, and positive and negative predictive values were 7.4% and 90.8%, respectively.

Conclusion

Elevated OPG autoantibody levels do not predict low bone mineral density in middle-aged women selected from the general population.

Validity of histology for the diagnosis of paediatric coeliac disease: a Swedish multicentre study

OBJECTIVE Histological evaluation of intestinal biopsies for the diagnosis of coeliac disease can be challenging and compatible with risk of misdiagnosis. The aim was to evaluate the agreement of pathological diagnosis for coeliac disease in children investigated at four major paediatric university hospitals in Sweden. MATERIALS AND METHODS Intestinal duodenal biopsies were collected from 402 children at median 9.7 years (1.4-18.3 years). A pathologist at each hospital performed the primary evaluation. A designated pathologist, blinded to the primary evaluation, performed a second Marsh classification of biopsies (M0 to M3c) taken from the bulb and duodenum separately. Kappa (κ) scores between first and second evaluation determined the agreement. Plasma samples were collected at the day of intestinal biopsy and analysed for tissue transglutaminase autoantibodies (tTGA) using radioligand-binding assays. RESULTS Marsh scores were concordant in 229/356 biopsies (64%, κ = 0.52, p < 0.0001). Among discordant results, 15/127 (12%) showed M0 in distal duodenum but ≥ M2 in the bulb, whereas the opposite was true for 8/127 (6%) of the biopsies. There were fewer collected duodenal biopsies, more missing bulb biopsies and missing CD3 staining among discordant evaluations. The second evaluation revealed a Marsh score compliant with coeliac disease in 22 children of whom seven children were tTGA positive. CONCLUSIONS The variation between university hospitals on the pathological evaluation of biopsies may lead to misdiagnosis of coeliac disease in paediatric patients. Access to clinical and endoscopic information as well as tTGA levels may be useful for the pathologist to complement the evaluation in dubious cases.

Role of proneurotensin as marker of paediatric coeliac disease

Neurotensin (NT) is a gut hormone functioning proinflammatory through nuclear factor kappa B (NF-κB) and interleukin (IL)-8 secretion or anti-inflammatory through epidermal growth factor receptors. NT mRNA is down-regulated in duodenal biopsies of children with untreated coeliac disease. The aim of this study was to investigate if plasma pro-NT levels correlated with the degree of intestinal mucosal damage and tissue transglutaminase autoantibody (tTGA) levels in children with coeliac disease. Fasting plasma samples from 96 children with coeliac disease and 89 non-coeliac disease controls were analysed for NT precursor fragment pro-NT 1-117 by a chemiluminometric immunoassay. Pro-NT levels were compared with NT mRNA from duodenal biopsies, assessed previously with quantitative polymerase chain reaction (PCR). Illumina core exome arrays were used for human leucocyte antigen (HLA) typing and the Marsh criteria applied to score mucosal damage. Tissue TGA was measured by radio binding assay. A general linear model compared pro-NT levels with diagnosis of coeliac disease, Marsh score and HLA DQ haplotype. Spearman's rank test was used to compare pro-NT levels with tTGA, age and duodenal NT mRNA levels, respectively. Plasma pro-NT levels were elevated in children with coeliac disease (median 23 pmol/l higher, P = 0·003) and in those with severe intestinal mucosal damage (median 24 pmol/l higher for ≥ Marsh 3b versus not, P = 0·0004). Pro-NT levels correlated further with tTGA (r²  = 0·22, P = 0·002), but not with duodenal NTS mRNA levels (r²  = -0·12, P = 0·14). Pro-NT was not associated with any of the HLA risk-haplotypes. Elevated peripheral pro-NT levels reflect more severe forms of active coeliac disease, indicating a potential role of NT in intestinal inflammation.

Genes involved in muscle contractility and nutrient signaling pathways within celiac disease risk loci show differential mRNA expression

Background

Risk gene variants for celiac disease, identified in genome-wide linkage and association studies, might influence molecular pathways important for disease development. The aim was to examine expression levels of potential risk genes close to these variants in the small intestine and peripheral blood and also to test if the non-coding variants affect nearby gene expression levels in children with celiac disease.

Methods

Intestinal biopsy and peripheral blood RNA was isolated from 167 children with celiac disease, 61 with potential celiac disease and 174 disease controls. Transcript levels for 88 target genes, selected from celiac disease risk loci, were analyzed in biopsies of a smaller sample subset by qPCR. Differentially expressed genes (3 from the pilot and 8 previously identified) were further validated in the larger sample collection (n = 402) of both tissues and correlated to nearby celiac disease risk variants.

Results

All genes were significantly down- or up-regulated in the intestinal mucosa of celiac disease children, NTS being most down-regulated (Fold change 3.6, p < 0.001). In contrast, PPP1R12B isoform C was up-regulated in the celiac disease mucosa (Fold change 1.9, p < 0.001). Allele specific expression of GLS (rs6741418, p = 0.009), INSR (rs7254060, p = 0.003) and NCALD (rs652008, p = 0.005) was also detected in the biopsies. Two genes (APPL2 and NCALD) were differentially expressed in peripheral blood but no allele specific expression was observed in this tissue.

Conclusion

The differential expression of NTS and PPP1R12B indicate a potential role for smooth muscle contractility and cell proliferation in celiac disease, whereas other genes like GLS, NCALD and INSR suggests involvement of nutrient signaling and energy homeostasis in celiac disease pathogenesis. A disturbance in any of these pathways might contribute to development of childhood celiac disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-015-0190-1) contains supplementary material, which is available to authorized users.

Neuropeptide Y autoantibodies in patients with long-term type 1 and type 2 diabetes and neuropathy

AIMS

The neurotransmitter Neuropeptide Y (NPY) was previously reported as a minor autoantigen in newly diagnosed type 1 diabetes (T1D) patients. The single nucleotide polymorphism at rs16139 (T1128C, L7P) in the NPY gene was associated with an increased risk for the development of type 2 diabetes (T2D). We aimed to develop a radiobinding assay for NPY-L (Leucine) and NPY-P (Proline) autoantibodies (A) to study the levels and the association with other islet autoantibodies and neuropathy.

METHODS

Autoantibodies against NPY-L, NPY-P, ZnT8, GAD65 and IA-2 were studied in T1D (n=48) and T2D (n=26) patients with duration up to 42 and 31years. A subgroup of T1D (n=32) patients re-examined, 5-8years after first visit, was tested for peripheral (Z-score) and autonomic neuropathy (E/I ratio).

RESULTS

NPY-LA and NPY-PA were detected in 23% and 19% in T1D (p<0.001), and 12% and 23% in T2D patients (p<0.001) compared to 2.5% controls (n=398). The levels of NPYA declined during follow-up in the T1D patients (p<0.001). The neuropathy was not related to the NPYA or the other islet autoantibodies.

CONCLUSIONS

Regardless of the absence of an association between NPYA and neuropathy, NPY may contribute to the pathogenesis of T1D and T2D as a minor autoantigen.

A possible mechanism behind autoimmune disorders discovered by genome-wide linkage and association analysis in celiac disease

Celiac disease is a common autoimmune disorder characterized by an intestinal inflammation triggered by gluten, a storage protein found in wheat, rye and barley. Similar to other autoimmune diseases such as type 1 diabetes, psoriasis and rheumatoid arthritis, celiac disease is the result of an immune response to self-antigens leading to tissue destruction and production of autoantibodies. Common diseases like celiac disease have a complex pattern of inheritance with inputs from both environmental as well as additive and non-additive genetic factors. In the past few years, Genome Wide Association Studies (GWAS) have been successful in finding genetic risk variants behind many common diseases and traits. To complement and add to the previous findings, we performed a GWAS including 206 trios from 97 nuclear Swedish and Norwegian families affected with celiac disease. By stratifying for HLA-DQ, we identified a new genome-wide significant risk locus covering the DUSP10 gene. To further investigate the associations from the GWAS we performed pathway analyses and two-locus interaction analyses. These analyses showed an over-representation of genes involved in type 2 diabetes and identified a set of candidate mechanisms and genes of which some were selected for mRNA expression analysis using small intestinal biopsies from 98 patients. Several genes were expressed differently in the small intestinal mucosa from patients with celiac autoimmunity compared to intestinal mucosa from control patients. From top-scoring regions we identified susceptibility genes in several categories: 1) polarity and epithelial cell functionality; 2) intestinal smooth muscle; 3) growth and energy homeostasis, including proline and glutamine metabolism; and finally 4) innate and adaptive immune system. These genes and pathways, including specific functions of DUSP10, together reveal a new potential biological mechanism that could influence the genesis of celiac disease, and possibly also other chronic disorders with an inflammatory component.