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- Gustafsson Bragde, Hanna, 1979-
(författare)
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Biomarkers of Inflammation and Intestinal Mucosa Pathology in Celiac Disease
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Celiac disease (CD) is a chronic small intestinal immune-mediated enteropathy triggered by gluten. The only currently available treatment is complying with a lifelong gluten-free diet, which should not be commenced before a CD diagnosis has been established by diagnostic test results (including histopathologic assessment of small intestinal biopsies and CD-specific antibody levels). This makes diagnostic swiftness and accuracy important. In cases with low CD-specific antibody levels and/or low-grade intestinal injuries the diagnosis can be difficult to establish. The main objective of this thesis was to complement and improve CD diagnostics by identifying and implementing new biomarkers, mainly based on gene expression, in small intestinal biopsies and blood. In paper I, genes were selected to reflect villous height, crypt elongation, immune response, and epithelial integrity. The results showed that a subset of those genes could discriminate active CD mucosa from mucosa without CD-related changes and grade the intestinal injury. In paper III, an unbiased investigation of gene expression in CD mucosa was performed using transcriptome analysis. Active CD and non-CD mucosa showed differential expression in a subset of genes, and some were differentially expressed in CD mucosa before histopathologic assessment could confirm intestinal alterations compatible with a CD diagnosis. Gene set analysis revealed that there are many biological processes affected in CD mucosa, including those associated with immune response, microbial infection, phagocytosis, intestinal barrier function, metabolism, and transportation.In parallel, gene expression was investigated in stabilised whole blood. Blood is a more accessible sampling material than intestinal biopsies, and stabilised blood is suitable for routine diagnostics since transcript levels are preserved at sampling. In paper II, expressions from a selection of genes were quantified in stabilised whole blood (RNA) and/or plasma (protein). Three genes with differential expression in CD were identified. Compared to the CD-specific autoantibodies against tissue transglutaminase (anti-TG2) alone, the addition of the information from the new potential markers resulted in a nonsignificant contribution to the diagnostic capacity of anti-TG2. An unbiased investigation using transcriptome analysis (paper IV) showed that gene level expression differences in stabilised whole blood were small between CD and non-CD. However, expression differences on a gene set level could potentially be used in CD diagnostics. CD-associated biological processes suggested by the results included a pro-inflammatory response, negative regulation of viral replication, proliferation, differentiation, cell migration, cell survival, translation, and haemostasis.Expression analysis using real-time polymerase chain reaction (PCR) is easy to perform, with instrumentation available at most clinical laboratories. Although select solitary biomarkers could be very useful in the diagnosis of CD, basing gene expression profiles on pathway information instead of single genes might also disclose disease heterogeneity between patients and add stability to a diagnostic method based on gene expressions. In conclusion, the results of this work demonstrate that analysing the expression of a few small intestinal genes can complement CD diagnostics. The application of gene expression analysis in cases with minor small intestine histopathological changes shows promising results, but needs further investigations. Additionally, gene expressions in other inflammatory diseases of the small intestine need to be investigated and compared with CD to complete the picture. Moreover, the findings from this work give clues about the biological contexts in which CD resides, and the potential of gene expression in blood at a gene set level is of interest for further investigations.
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| 2. |
- Gustafsson Bragde, Hanna, 1979-, et al.
(författare)
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Characterisation of gene and pathway expression in stabilised blood from children with coeliac disease
- 2020
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Ingår i: BMJ open gastroenterology. - : BMJ. - 2054-4774. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: A coeliac disease (CD) diagnosis is likely in children with levels of tissue transglutaminase autoantibodies (anti-TG2) >10 times the upper reference value, whereas children with lower anti-TG2 levels need an intestinal biopsy to confirm or rule out CD. A blood sample is easier to obtain than an intestinal biopsy sample, and stabilised blood is suitable for routine diagnostics because transcript levels are preserved at sampling. Therefore, we investigated gene expression in stabilised whole blood to explore the possibility of gene expression-based diagnostics for the diagnosis and follow-up of CD.DESIGN: We performed RNA sequencing of stabilised whole blood from active CD cases (n=10), non-CD cases (n=10), and treated CD cases on a gluten-free diet (n=10) to identify diagnostic CD biomarkers and pathways involved in CD pathogenesis.RESULTS: No single gene was differentially expressed between the sample groups. However, by using gene set enrichment analysis (GSEA), significantly differentially expressed pathways were identified in active CD, and these pathways involved the inflammatory response, negative regulation of viral replication, translation, as well as cell proliferation, differentiation, migration, and survival. The results indicate that there are differences in pathway regulation in CD, which could be used for diagnostic purposes. Comparison between GSEA results based on stabilised blood with GSEA results based on small intestinal biopsies revealed that type I interferon response, defence response to virus, and negative regulation of viral replication were identified as pathways common to both tissues.CONCLUSIONS: Stabilised whole blood is not a suitable sample for clinical diagnostics of CD based on single genes. However, diagnostics based on a pathway-focused gene expression panel may be feasible, but requires further investigation.
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