Comparison of DNA methylation profiles from saliva in Coeliac disease and non-coeliac disease individuals.

BACKGROUND: Coeliac disease (CD) is a autoimmune disease characterised by mucosal inflammation in the small intestine in response to dietary gluten. Genetic factors play a key role with CD individuals carrying either the HLA-DQ2 or HLA-DQ8 haplotype, however these haplotypes are present in half the general population making them necessary but insufficient to cause CD. Epigenetic modifications, including DNA methylation that can change in response to environmental exposure could help to explain how interactions between genes and environmental factors combine to trigger disease development. Identifying changes in DNA methylation profiles in individuals with CD could help discover novel genomic regions involved in the onset and development of CD. METHODS: The Illumina InfiniumMethylation450 Beadchip array (HM450) was used to compare DNA methylation profiles in saliva, in CD and non-CD affected individuals. CD individuals who had been diagnosed at least 2 years previously; were on a GFD; and who were currently asymptomatic; were compared to age and sex-matched non-CD affected healthy controls. Bisulphite pyrosequencing was used to validate regions found to be differentially methylated. These regions were also validated in a second larger cohort of CD and non-CD affected individuals. RESULTS: Methylation differences within the HLA region at HLA-DQB1 were identified on HM450 but could not be confirmed with pyrosequencing. Significant methylation differences near the SLC17A3 gene were confirmed on pyrosequencing in the initial pilot cohort. Interestingly pyrosequencing sequencing of these same sites within a second cohort of CD and non-CD affected controls produced significant methylation differences in the opposite direction. CONCLUSION: Altered DNA methylation profiles appear to be present in saliva in CD individuals. Further work to confirm whether these differences are truly associated with CD is needed.

Comparing DNA methylation profiles in saliva and intestinal mucosa.

BACKGROUND: Altered epigenetic profiles are a feature of intestinal diseases, including ulcerative colitis and Crohn's disease. DNA methylation studies in these diseases have utilised intestinal mucosal tissue or blood which can be difficult to collect, particularly for large-scale research studies. Saliva is an attractive alternative for epigenetic studies as it is easy to collect and provides high quality methylation profiles. The aim of the study was to determine the utility of saliva as an alternative for DNA methylation studies of intestinal disorders. RESULTS: DNA methylation in saliva and intestinal mucosa samples were compared in individuals (n = 10) undergoing endoscopies using the Illumina Infinium Methylation 450 K Beadchip array. We found that DNA methylation was correlated between tissue types within an individual (Pearson correlation co-efficient r = 0.92 to 0.95, p < 0.001). Of the 48,541 probes (approximately 11% of CpG sites) that were differentially methylated between saliva and intestinal mucosa (adjusted p < 0.001, |Δß| ≥ 20%), these mapped to genes involved in tissue-specific pathways, including the apelin signalling and oxytocin pathways which are important in gastrointestinal cytoprotection and motility. CONCLUSIONS: This study suggests that saliva has the potential to be used as an alternate DNA source to invasive intestinal mucosa for DNA methylation research into intestinal conditions.

Does Telomere Shortening Precede the Onset of Hypertension in Spontaneously Hypertensive Mice?

Telomere length is widely considered as a marker of biological aging. Clinical studies have reported associations between reduced telomere length and hypertension. The aim of this study was to compare telomere length in hypertensive and normotensive mice at pre-disease and established disease time points to determine whether telomere length differs between the strains before and after the onset of disease. Genomic DNA was extracted from kidney and heart tissues of 4-, 12-, and 20-week-old male hypertensive (BPH/2J) and normotensive (BPN/3J) mice. Relative telomere length (T/S) was measured using quantitative PCR. Age was inversely correlated with telomere length in both strains. In 4-week-old pre-hypertensive animals, no difference in T/S was observed between BPH/2J and BPN/3J animals in kidney or heart tissue (kidney p = 0.14, heart p = 0.06). Once the animals had established disease, at 12 and 20 weeks, BPH/2J mice had significantly shorter telomeres when compared to their age-matched controls in both kidney (12 weeks p < 0.001 and 20 weeks p = 0.004) and heart tissues (12 weeks p < 0.001 and 20 weeks p < 0.001). This is the first study to show that differences in telomere lengths between BPH/2J and BPN/3J mice occur after the development of hypertension and do not cause hypertension in the BPH/2J mice.

Development of a Risk Score for Extraintestinal Manifestations of Coeliac Disease.

The aim of this study was to identify indicators of coeliac disease (CD) in an Australian cohort, beyond the known gastrointestinal symptoms. Individuals were recruited from the general population and at the 2014 Gluten Free Expo in Sydney and in Melbourne, Australia. Data on their current health status including medical history, diagnosis for CD, and family history were collected. Multivariable logistic regression was used to identify independent predictors of CD. A weighted risk score system was then generated for the independent predictors, and a risk score was calculated for each individual. A total of 301 individuals were included in the study. We found an association between CD and having a family history of CD (odds ratio [OR] 7.6, 95%confidence interval [CI] 3.7-15.6), an autoimmune disorder (OR 2.1, 95%CI 1.1-4.1), anemia (OR 5.8, 95%CI 2.8-11.9), lactose intolerance (OR 4.5, 95%CI 1.2-17.7), and depression (OR 4.8, 95%CI 1.9-11.6). Risk score analysis found individuals in the medium (OR 4.8, 95%CI 2.5 to 9.3) and high-risk (OR 36.6, 95%CI 16.4 to 81.6) groups were significantly more likely to report having CD compared with those in the low-risk group. This study identifies a set of factors more commonly observed in individuals with CD, beyond the traditional gastrointestinal complaints. These include a family history of CD, the presence of another autoimmune disorder, anemia, lactose intolerance, and depression. A risk score was developed (Coeliac Risk COMPARE) which scores individuals based on the presence or absence of these additional symptoms and provides an additional screening tool when assessing whether the patient requires follow-up testing for CD.

Identification of genes with altered expression in male and female Schlager hypertensive mice.

BACKGROUND: Numerous studies have shown sex differences in the onset and severity of hypertension. Despite these sex-differences the majority of animal studies are carried out in males. This study investigated expression changes in both male and female hypertensive mouse kidneys to identify common mechanisms that may be involved in the development of hypertension. METHODS: The Schlager hypertensive mouse model (BPH/2J) and its normotensive control (BPN/3J) were used in this study. Radiotelemetry was performed on 12 to 13 week old BPH/2J and BPN/3J male and female animals. Affymetrix GeneChip Mouse Gene 1.0 ST Arrays were performed in kidney tissue from 12 week old BPH/2J and BPN/3J male and female mice (n = 6/group). Genes that were differentially expressed in both male and female datasets were validated using qPCR. RESULTS: Systolic arterial pressure and heart rate was significantly higher in BPH/2J mice compared with BPN/3J mice in both males and females. Microarray analysis identified 153 differentially expressed genes that were common between males and females (70 upregulated and 83 downregulated). We validated 15 genes by qPCR. Genes involved in sympathetic activity (Hdc, Cndp2), vascular ageing (Edn3), and telomere maintenance (Mcm6) were identified as being differentially expressed between BPH/2J and BPN/3J comparisons. Many of these genes also exhibited expression differences between males and females within a strain. CONCLUSIONS: This study utilised data from both male and female animals to identify a number of genes that may be involved in the development of hypertension. We show that female data can be used to refine candidate genes and pathways, as well as highlight potential mechanisms to explain the differences in prevalence and severity of disease between men and women.