Gut virome-colonising Orthohepadnavirus genus is associated with ulcerative colitis pathogenesis and induces intestinal inflammation in vivo

OBJECTIVES

Ulcerative colitis (UC) is a chronic inflammatory disorder of unknown aetiology. Gut virome dysbiosis is fundamental in UC progression, although its role in the early phases of the disease is far from fully understood. Therefore, we sought to investigate the role of a virome-associated protein encoded by the Orthohepadnavirus genus, the hepatitis B virus X protein (HBx), in UC aetiopathogenesis.

DESIGN

HBx positivity of UC patient-derived blood and gut mucosa was assessed by RT-PCR and Sanger sequencing and correlated with clinical characteristics by multivariate analysis. Transcriptomics was performed on HBx-overexpressing endoscopic biopsies from healthy donors.C57BL/6 mice underwent intramucosal injections of liposome-conjugated HBx-encoding plasmids or the control, with or without antibiotic treatment. Multidimensional flow cytometry analysis was performed on colonic samples from HBx-treated and control animals. Transepithelial electrical resistance measurement, proliferation assay, chromatin immunoprecipitation assay with sequencing and RNA-sequencing were performed on in vitro models of the gut barrier. HBx-silencing experiments were performed in vitro and in vivo.

RESULTS

HBx was detected in about 45% of patients with UC and found to induce colonic inflammation in mice, while its silencing reverted the colitis phenotype in vivo. HBx acted as a transcriptional regulator in epithelial cells, provoking barrier leakage and altering both innate and adaptive mucosal immunity ex vivo and in vivo.

CONCLUSION

This study described HBx as a contributor to the UC pathogenesis and provides a new perspective on the virome as a target for tailored treatments.

Polymorphic variants involved in methylation regulation: a strategy to discover risk loci for pancreatic ductal adenocarcinoma

INTRODUCTION

Only a small number of risk factors for pancreatic ductal adenocarcinoma (PDAC) has been established. Several studies identified a role of epigenetics and of deregulation of DNA methylation. DNA methylation is variable across a lifetime and in different tissues; nevertheless, its levels can be regulated by genetic variants like methylation quantitative trait loci (mQTLs), which can be used as a surrogate.

MATERIALS AND METHODS

We scanned the whole genome for mQTLs and performed an association study in 14 705 PDAC cases and 246 921 controls. The methylation data were obtained from whole blood and pancreatic cancer tissue through online databases. We used the Pancreatic Cancer Cohort Consortium and the Pancreatic Cancer Case-Control Consortium genome-wide association study (GWAS) data as discovery phase and the Pancreatic Disease Research consortium, the FinnGen project and the Japan Pancreatic Cancer Research consortium GWAS as replication phase.

RESULTS

The C allele of 15q26.1-rs12905855 showed an association with a decreased risk of PDAC (OR=0.90, 95% CI 0.87 to 0.94, p=4.93×10-8 in the overall meta-analysis), reaching genome-level statistical significance. 15q26.1-rs12905855 decreases the methylation of a 'C-phosphate-G' (CpG) site located in the promoter region of the RCCD1 antisense (RCCD1-AS1) gene which, when expressed, decreases the expression of the RCC1 domain-containing (RCCD1) gene (part of a histone demethylase complex). Thus, it is possible that the rs12905855 C-allele has a protective role in PDAC development through an increase of RCCD1 gene expression, made possible by the inactivity of RCCD1-AS1.

CONCLUSION

We identified a novel PDAC risk locus which modulates cancer risk by controlling gene expression through DNA methylation.

Genetic and non-genetic risk factors for early-onset pancreatic cancer

BACKGROUND

Early-onset pancreatic cancer (EOPC) represents 5-10% of all pancreatic ductal adenocarcinoma (PDAC) cases, and the etiology of this form is poorly understood. It is not clear if established PDAC risk factors have the same relevance for younger patients. This study aims to identify genetic and non-genetic risk factors specific to EOPC.

METHODS

A genome-wide association study was performed, analysing 912 EOPC cases and 10 222 controls, divided into discovery and replication phases. Furthermore, the associations between a polygenic risk score (PRS), smoking, alcohol consumption, type 2 diabetes and PDAC risk were also assessed.

RESULTS

Six novel SNPs were associated with EOPC risk in the discovery phase, but not in the replication phase. The PRS, smoking, and diabetes affected EOPC risk. The OR comparing current smokers to never-smokers was 2.92 (95% CI 1.69-5.04, P = 1.44 × 10-4). For diabetes, the corresponding OR was 14.95 (95% CI 3.41-65.50, P = 3.58 × 10-4).

CONCLUSION

In conclusion, we did not identify novel genetic variants associated specifically with EOPC, and we found that established PDAC risk variants do not have a strong age-dependent effect. Furthermore, we add to the evidence pointing to the role of smoking and diabetes in EOPC.

Exploring the Neandertal legacy of pancreatic ductal adenocarcinoma risk in Eurasians

BACKGROUND

The genomes of present-day non-Africans are composed of 1-3% of Neandertal-derived DNA as a consequence of admixture events between Neandertals and anatomically modern humans about 50-60 thousand years ago. Neandertal-introgressed single nucleotide polymorphisms (aSNPs) have been associated with modern human disease-related traits, which are risk factors for pancreatic ductal adenocarcinoma (PDAC), such as obesity, type 2 diabetes, and inflammation. In this study, we aimed at investigating the role of aSNPs in PDAC in three Eurasian populations.

RESULTS

The high-coverage Vindija Neandertal genome was used to select aSNPs in non-African populations from 1000 Genomes project phase 3 data. Then, the association between aSNPs and PDAC risk was tested independently in Europeans and East Asians, using existing GWAS data on more than 200 000 individuals. We did not find any significant associations between aSNPs and PDAC in samples of European descent, whereas, in East Asians, we observed that the Chr10p12.1-rs117585753-T allele (MAF = 10%) increased the risk to develop PDAC (OR = 1.35, 95%CI 1.19-1.54, P = 3.59 × 10-6), with a P-value close to a threshold that takes into account multiple testing.

CONCLUSIONS

Our results show only a minimal contribution of Neandertal SNPs to PDAC risk.

The PANcreatic Disease ReseArch (PANDoRA) consortium: Ten years' experience of association studies to understand the genetic architecture of pancreatic cancer

Pancreatic cancer has an incidence that almost matches its mortality. Only a small number of risk factors and 33 susceptibility loci have been identified. so Moreover, the relative rarity of pancreatic cancer poses significant hurdles for research aimed at increasing our knowledge of the genetic mechanisms contributing to the disease. Additionally, the inability to adequately power research questions prevents small monocentric studies from being successful. Several consortia have been established to pursue a better understanding of the genetic architecture of pancreatic cancers. The Pancreatic disease research (PANDoRA) consortium is the largest in Europe. PANDoRA is spread across 12 European countries, Brazil and Japan, bringing together 29 basic and clinical research groups. In the last ten years, PANDoRA has contributed to the discovery of 25 susceptibility loci, a feat that will be instrumental in stratifying the population by risk and optimizing preventive strategies.

Dissecting the genetic heterogeneity of gastric cancer

BACKGROUND

Gastric cancer (GC) is clinically heterogenous according to location (cardia/non-cardia) and histopathology (diffuse/intestinal). We aimed to characterize the genetic risk architecture of GC according to its subtypes. Another aim was to examine whether cardia GC and oesophageal adenocarcinoma (OAC) and its precursor lesion Barrett's oesophagus (BO), which are all located at the gastro-oesophageal junction (GOJ), share polygenic risk architecture.

METHODS

We did a meta-analysis of ten European genome-wide association studies (GWAS) of GC and its subtypes. All patients had a histopathologically confirmed diagnosis of gastric adenocarcinoma. For the identification of risk genes among GWAS loci we did a transcriptome-wide association study (TWAS) and expression quantitative trait locus (eQTL) study from gastric corpus and antrum mucosa. To test whether cardia GC and OAC/BO share genetic aetiology we also used a European GWAS sample with OAC/BO.

FINDINGS

Our GWAS consisting of 5816 patients and 10,999 controls highlights the genetic heterogeneity of GC according to its subtypes. We newly identified two and replicated five GC risk loci, all of them with subtype-specific association. The gastric transcriptome data consisting of 361 corpus and 342 antrum mucosa samples revealed that an upregulated expression of MUC1, ANKRD50, PTGER4, and PSCA are plausible GC-pathomechanisms at four GWAS loci. At another risk locus, we found that the blood-group 0 exerts protective effects for non-cardia and diffuse GC, while blood-group A increases risk for both GC subtypes. Furthermore, our GWAS on cardia GC and OAC/BO (10,279 patients, 16,527 controls) showed that both cancer entities share genetic aetiology at the polygenic level and identified two new risk loci on the single-marker level.

INTERPRETATION

Our findings show that the pathophysiology of GC is genetically heterogenous according to location and histopathology. Moreover, our findings point to common molecular mechanisms underlying cardia GC and OAC/BO.

FUNDING

German Research Foundation (DFG).

Mucosal Microbiota from Colorectal Cancer, Adenoma and Normal Epithelium Reveals the Imprint of Fusobacterium nucleatum in Cancerogenesis

An increasing amount of evidence suggests the emerging role of the gut microbiota in the development of colorectal cancer (CRC). This study aimed to elucidate the architecture of microbial communities within normal and neoplastic colonic mucosa.

METHODS

Microbiota were analyzed by NGS and by an ensemble of metagenomics analysis tools in a total of 69 tissues from 9 patients with synchronous colorectal neoplasia and adenomas (27 specimens: 9 from normal tissues, 9 adenomas, and 9 tumours), 16 patients with only colonic adenomas (32 specimens: 16 from normal tissues and 16 adenomas), and from healthy subjects (10 specimens of normal mucosa).

RESULTS

Weak differences were observed in alpha and beta metrics among the synchronous tissues from CRC and controls. Through pairwise differential abundance analyses of sample groups, an increasing trend of Rikenellaceae, Pseudomonas and Fusobacterium, and decreasing trends of Staphylococcus, Actinobacillus and Gemmiger were observed in CRC, while Staphylococcus and Bifidobacterium were decreased in patients with only adenomas. At RT-qPCR analysis, Fusobacterium nucleatum was significantly enriched in all the tissues of subjects with synchronous colorectal neoplasia.

CONCLUSION

Our findings provide a comprehensive view of the human mucosa-associated gut microbiota, emphasizing global microbial diversity mostly in synchronous lesions and proving the constant presence of Fusobacterium nucleatum, with its ability to drive carcinogenesis.

Evaluation of inherited germline mutations in cancer susceptibility genes among pancreatic cancer patients: a single-center study

BACKGROUND

Germline mutations in cancer susceptibility genes were identified in pancreatic cancer (PanC) patients with a sporadic disease and in those unselected for family cancer history.

METHODS

With the aim to determine the prevalence of germline predisposition genes mutations in PanC, and to evaluate whether they were associated with the presence of PanC, we profiled a custom AmpliSeq panel of 27 cancer susceptibility genes in 47 PanC patients and 51 control subjects by using the Ion Torrent PGM system.

RESULTS

Multigene panel testing identified a total of 31 variants in 27 PanC (57.4%), including variants with pathogenic/likely pathogenic effect, those of uncertain significance, and variants whose clinical significance remains currently undefined. Five patients carried more than one variant in the same gene or in different genes. Eight patients (17.0%) had at least one pathogenic/likely pathogenic variant in four main genes: CFTR (10.6%), BRCA2 (8.5%), ATM and CHEK2 (2.1%). Pathogenic/likely pathogenic mutation were identified in patients with positive PanC family history (20%) or in patients without first-degree relatives affected by PanC (13.6%). All the BRCA2 mutation carriers were unselected PanC patients. The presence of mutations in BRCA2 was significantly associated with an increased occurrence of PanC and with positive family history for endometrial cancer (p = 0.018).

CONCLUSIONS

This study confirmed the potential remarkable contribution of BRCA2 in assessing the presence of PanC. Overall our findings supported the recommendation of offering the germline testing to all the PanC patients with the intent to reduce the number of underdiagnosed carriers of mutations in predisposition genes, and not to preclude their relatives from the opportunity to benefit from surveillance programs.

Downexpression of miR-200c-3p Contributes to Achalasia Disease by Targeting the PRKG1 Gene

Achalasia is an esophageal smooth muscle motility disorder with unknown pathogenesis. Taking into account our previous results on the downexpression of miR-200c-3p in tissues of patients with achalasia correlated with an increased expression of PRKG1, SULF1, and SYDE1 genes, our aim was to explore the unknown biological interaction between these genes and human miR-200c-3p and if this relation could unravel their functional role in the etiology of achalasia. To search for putative miR-200c-3p binding sites in the 3'-UTR of PRKG1, SULF1 and SYDE1, a bioinformatics tool was used. To test whether PRKG1, SULF1, and SYDE1 are targeted by miR-200c-3p, a dual-luciferase reporter assay and quantitative PCR on HEK293 and fibroblast cell lines were performed. To explore the biological correlation between PRKG1 and miR-200c-3p, an immunoblot analysis was carried out. The overexpression of miR-200c-3p reduced the luciferase activity in cells transfected with a luciferase reporter containing a fragment of the 3'-UTR regions of PRKG1, SULF1, and SYDE1 which included the miR-200c-3p seed sequence. The deletion of the miR-200c-3p seed sequence from the 3'-UTR fragments abrogated this reduction. A negative correlation between miR-200c-3p and PRKG1, SULF1, and SYDE1 expression levels was observed. Finally, a reduction of the endogenous level of PRKG1 in cells overexpressing miR-200c-3p was detected. Our study provides, for the first time, functional evidence about the PRKG1 gene as a direct target and SULF1 and SYDE1 as potential indirect substrates of miR-200c-3p and suggests the involvement of NO/cGMP/PKG signaling in the pathogenesis of achalasia.

A PCR-based method for the diagnosis of Enterobius vermicularis in stool samples, specifically designed for clinical application

BACKGROUND

Enterobius vermicularis (E. vermicularis) is a nematode that infects up to 200 million people worldwide, despite effective medications being available. Conventional diagnostic tests are hindered by low sensitivity and poor patient compliance. Furthermore, no biomolecular techniques are available for clinical application. The aim of this study was to develop a procedure specifically designed for clinical application to detect E. vermicularis by means of PCR.

MATERIALS AND METHODS

Two subject groups were taken into account: a group of 27 infected patients and a control group of 27 healthy subjects. A nested-PCR was performed on fecal samples to detect E. vermicularis. Due to the intrinsic difficulties of the fecal matrix, several countermeasures were adopted to ensure the efficient performance of the method: (a) a large amount of feces for the extraction process (20 g instead of 200 mg); (b) a combination of chemical and physical treatments to grind the fecal matrix; (c) an additional purification process for the negative samples after the first nested-PCR; and (d) the selection of a very specific target region for the PCR.

RESULTS

Due to the lack of overlap with other organisms, a sequence of the 5S ribosomal DNA (rDNA) spacer region including the tract SL1 was chosen to design appropriate external and internal primers. The first nested-PCR detected E.vermicularis in 19/27 samples from infected patients. After further purification, 5/8 of the negative samples resulted positive at the second PCR. Conversely, all the samples from healthy controls resulted negative to both PCRs. Sensitivity and specificity of the method were, respectively, 88.9% and 100%.

CONCLUSION

The results prove the high diagnostic accuracy of the proposed method, addressing and overcoming the challenges posed by both conventional tests and PCR-based approaches. Therefore, the method can be proposed for clinical application.

Detailed stratified GWAS analysis for severe COVID-19 in four European populations

Given the highly variable clinical phenotype of Coronavirus disease 2019 (COVID-19), a deeper analysis of the host genetic contribution to severe COVID-19 is important to improve our understanding of underlying disease mechanisms. Here, we describe an extended genome-wide association meta-analysis of a well-characterized cohort of 3255 COVID-19 patients with respiratory failure and 12 488 population controls from Italy, Spain, Norway and Germany/Austria, including stratified analyses based on age, sex and disease severity, as well as targeted analyses of chromosome Y haplotypes, the human leukocyte antigen region and the SARS-CoV-2 peptidome. By inversion imputation, we traced a reported association at 17q21.31 to a ~0.9-Mb inversion polymorphism that creates two highly differentiated haplotypes and characterized the potential effects of the inversion in detail. Our data, together with the 5th release of summary statistics from the COVID-19 Host Genetics Initiative including non-Caucasian individuals, also identified a new locus at 19q13.33, including NAPSA, a gene which is expressed primarily in alveolar cells responsible for gas exchange in the lung.

Adherence to Gluten-Free Diet Restores Alpha Diversity in Celiac People but the Microbiome Composition Is Different to Healthy People

Celiac disease (CD) is an autoimmune disease with the destruction of small intestinal villi, which occurs in genetically predisposed individuals. At the present moment, a gluten-free diet (GFD) is the only way to restore the functionality of gut mucosa. However, there is an open debate on the effects of long-term supplementation through a GFD, because some authors report an unbalance in microbial taxa composition. Methods: For microbiome analysis, fecal specimens were collected from 46 CD individuals in GFD for at least 2 years and 30 specimens from the healthy controls (HC). Data were analyzed using an ensemble of software packages: QIIME2, Coda-lasso, Clr-lasso, Selbal, PICRUSt2, ALDEx2, dissimilarity-overlap analysis, and dysbiosis detection tests. Results: The adherence to GFD restored the alpha biodiversity of the gut microbiota in celiac people but microbial composition at beta diversity resulted as different to HC. The microbial composition of the CD subjects was decreased in a number of taxa, namely Bifidobacterium longum and several belonging to Lachnospiraceae family, whereas Bacteroides genus was found to be more abundant. Predicted metabolic pathways among the CD bacterial communities revealed an important role in tetrapyrrole biosynthesis. Conclusions: CD patients in GFD had a non-dysbiotic microbial composition for the crude alpha diversity metrics. We found significant differences in beta diversity, in certain taxon, and pathways between subjects with inactive CD in GFD and controls. Collectively, our data may suggest the development of new GFD products by modulating the gut microbiota through diet, supplements of vitamins, and the addition of specific prebiotics.

Genetically Determined Telomere Length Is Associated with Pancreatic Neuroendocrine Neoplasms Onset

INTRODUCTION

Telomere length (TL) is a potential indicator of cancer predisposition; however, the multitude of techniques used to measure it causes the results to be heterogeneous and, in some cases, controversial. In the last years, several studies adopted a strategy based on TL-associated genetic variants to generate a polygenic score, often referred as teloscore, used in lieu of direct TL measurement. For pancreatic neuroendocrine neoplasms (PanNEN), this strategy has not been attempted yet.

METHODS

A teloscore was generated using 11 SNPs (NAF1-rs7675998, ZNF676-rs409627, TERC-rs10936599, CTC1-rs3027234, PXK-rs6772228, DHX35-rs6028466, OBFC1-rs9420907, ZNF208-rs8105767, ACYP2-rs11125529, TERT-rs2736100, and ZBTB46-rs755017), and 291 PanNEN cases and 1,686 controls collected by the PANcreatic Disease ReseArch (PANDoRA) consortium were genotyped to analyse the association of the teloscore and its individual SNPs with the risk of developing PanNEN.

RESULTS

An association between genetically determined long telomeres and the risk of developing PanNEN (OR = 1.99, CI: 1.33-2.98, p = 0.0008) for highest versus median (third) quintile was observed. In addition, two novel SNPs associated with PanNEN risk were identified: ZNF676-rs409627 (ORC/C_vs_G/G = 2.27, CI: 1.58-3.27, p = 8.80 × 10-6) and TERT-rs2736100 (ORC/A_vs_C/C = 2.03, CI: 1.42-2.91, p = 1.06 × 10-4).

CONCLUSION

In conclusion, this study provides for the first time a clear indication of the association between long genetically determined telomeres and increased risk of developing PanNEN.

Germline Alterations in Patients With IBD-associated Colorectal Cancer

BACKGROUND

Patients with inflammatory bowel diseases (IBD), both ulcerative colitis (UC) and Crohn's disease (CD), are at risk of developing a colorectal cancer (CRC). No information is available on the contribution of patients' genetic background to CRC occurrence. This study investigates germline alterations in patients with IBD-associated CRC.

METHODS

We profiled a panel of 39 genes potentially involved in cancer predisposition and searched for germline variants in IBD patients with CRC or high-grade dysplasia.

RESULTS

After clinical exclusion of genetic cancer syndromes, 25 IBD patients (4 CD and 21 UC) with CRC or high-grade dysplasia were studied. After excluding variants with low likelihood of pathogenicity (classes 1 or 2 according the International Agency for Research on Cancer [IARC]), the panel identified pathogenic variants, likely pathogenic, or variants with unknown significance in 18 patients (72%). Six patients (24%) carried pathogenic or likely variants (IARC class 5 or 4). Of the identified variants, 4 encompassed the APC region, 3 the MLH1 gene, and the remaining ones the MSH2, MSH3, monoallelic MUTYH, EPCAM, BRCA1, CHEK2, POLD1, POLE, CDKN2A, and PDGFRA genes. Four patients carried at least 2 variants in different genes. Duration of IBD was significantly shorter in carriers of 4 or 5 IARC variants (7 years; range 0-21; P = .002) and in those with variants with unknown significance (12 years; range 0-22; P = .005) compared with patients without or with only benign variations (23.5 years; range 15-34).

CONCLUSIONS

In silico analysis and sequence-based testing of germline DNA from IBD patients with CRC or high-grade dysplasia detected 24% of variants positioned in pathogenic classes. In patients with type 3, 4, and 5 variants, the onset of high-grade dysplasia or CRC was significantly earlier than in patients with benign or unidentified variants. The screening for these genes could identify IBD patients requiring a more intensive endoscopic surveillance for earlier detection of dysplastic changes.

Healthy and pro-inflammatory gut ecology plays a crucial role in the digestion and tolerance of a novel Gluten Friendly™ bread in celiac subjects: a randomized, double blind, placebo control in vivo study

Gluten Friendly™ (GF) is a new gluten achieved through a physicochemical process applied to wheat kernels. The goal of this research was to assess the in vivo effects of Gluten Friendly™ bread on celiac gut mucosa and microbiota. In a double-blind placebo-controlled intervention study, 48 celiac disease (CD) patients were randomized into 3 groups to eat 100 g of bread daily, containing different doses (0; 3 g; 6 g) of GF for 12 weeks. The small-bowel morphology (VH/CrD), intraepithelial densities of CD3+, celiac serology, MUC2, CB1, gut permeability, proinflammatory cytokines, gluten in stools, symptoms, and gut microbial composition were assessed. All 48 CD subjects experienced no symptoms. K-means analysis evidenced celiac subjects clustering around unknown parameters independent of GF dosage: K1 35%; K2 30%; K3 35%. VH/CrD significantly decreased in K1 and K2. VH/CrD did not correlate with IEL increase in K2. 33-mer was not detected in 47% and 73% of patients in both K1 and K2, respectively. VH/CrD and IEL did not change significantly and strongly correlated with the absence of 33-mer in K3. Inflammation and VH/CrD decrease are strongly related with the presence of proinflammatory species at the baseline. A boost in probiotic, butyrate-producing genera, is strongly related with GF tolerance at the end of the trial. Our research suggests that a healthy and proinflammatory ecology could play a crucial role in the digestion and tolerance of the new gluten molecule in celiac subjects. However, GF can be completely digested by gut microbiota of CD subjects and shapes it toward gut homeostasis by boosting healthy butyrate-producing populations. The clinical trial registry number is NCT03137862 (https://clinicaltrials.gov).

Circulating levels of cytokines, chemokines and growth factors in patients with achalasia

Idiopathic achalasia is a disease that is characterized by the absence of peristalsis and incomplete relaxation of the lower esophageal sphincter, which is accompanied by dysphagia, regurgitation, chest pain and weight loss. The role of inflammatory infiltrates in the pathogenesis of achalasia remains controversial, although the infiltrating cell profile in the tissue has been previously characterized histologically and immunohistochemically. The present study aimed to evaluate the serum levels of 27 protein biomarkers to determine their association with achalasia and the clinical disease characteristics. The cytokine, chemokine and growth factor serum profiles of 68 patients with achalasia and 39 healthy individuals were explored using the 27-Bio-Plex Pro Human Cytokine assay. Reductions in the levels of inflammatory mediators IL-1β, IL-2, IL-5, IL-6, IL-8, IL-10, IL-12p70, IL-13, IL-15, IL-17, fibroblast growth factor, granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, interferon-γ, monocyte chemoattractant protein-1, macrophage inflammatory protein-1 (MIP-1)α and MIP-1β, regulated upon activation normal T cell expressed and presumably secreted, TNF-α and VEGF were detected in the serum samples of patients with achalasia compared with those in the control group (P<0.05). However, significant associations between the expression in the levels of inflammatory factors and clinical characteristics of the patients were not found (P>0.05). These results suggest that achalasia is a disease that has a local but not a systemic inflammatory pattern. Further studies are required to improve the current understanding of the mechanism underlying this disease.

Association of Genetic Variants Affecting microRNAs and Pancreatic Cancer Risk

Genetic factors play an important role in the susceptibility to pancreatic cancer (PC). However, established loci explain a small proportion of genetic heritability for PC; therefore, more progress is needed to find the missing ones. We aimed at identifying single nucleotide polymorphisms (SNPs) affecting PC risk through effects on micro-RNA (miRNA) function. We searched in silico the genome for SNPs in miRNA seed sequences or 3 prime untranslated regions (3'UTRs) of miRNA target genes. Genome-wide association data of PC cases and controls from the Pancreatic Cancer Cohort (PanScan) Consortium and the Pancreatic Cancer Case-Control (PanC4) Consortium were re-analyzed for discovery, and genotyping data from two additional consortia (PanGenEU and PANDoRA) were used for replication, for a total of 14,062 cases and 11,261 controls. None of the SNPs reached genome-wide significance in the meta-analysis, but for three of them the associations were in the same direction in all the study populations and showed lower value of p in the meta-analyses than in the discovery phase. Specifically, rs7985480 was consistently associated with PC risk (OR = 1.12, 95% CI 1.07-1.17, p = 3.03 × 10-6 in the meta-analysis). This SNP is in linkage disequilibrium (LD) with rs2274048, which modulates binding of various miRNAs to the 3'UTR of UCHL3, a gene involved in PC progression. In conclusion, our results expand the knowledge of the genetic PC risk through miRNA-related SNPs and show the usefulness of functional prioritization to identify genetic polymorphisms associated with PC risk.

Worse impact of second wave COVID-19 pandemic in adults but not in children with inflammatory bowel disease: an Italian single tertiary center experience

OBJECTIVE

From September 2020, a second wave of COVID-19 pandemic started. We aimed at exploring the impact of SARS-CoV-2 infection in IBD patients during the two waves.

PATIENTS AND METHODS

All IBD patients with a confirmed diagnosis of SARS-CoV-2 infection were enrolled. They were sorted into two groups (those infected before September 2020, and those from September 2020 to January 2021) and compared by demographic and clinical data.

RESULTS

Twenty-five patients (out of about 600 with a follow-up visit) were infected with SARS-CoV-2 (4.1%). Sixteen were male and the mean age was 46.5 ± 14.3 years (range 24-74). Six were smokers and 11 had comorbidities; 2 were on steroids and 17 on immunosuppressants or biologics. Three patients (12%) needed hospitalization and other three patients were treated with azithromycin, steroids and LMWH, all of them during the second wave. No patient died or developed any sequelae. Two subjects were infected during the first wave (0.3 vs. 3.83, p<0.0001). Non-significant differences were found between the two groups.

CONCLUSIONS

A higher number of IBD patients were infected during the second wave. No patient developed a severe form of pneumonia, even those treated with immunosuppressants or biologics. No risk factor for hospitalization was found.

Impact of the COVID-19 outbreak and the serum prevalence of SARS-CoV-2 antibodies in patients with inflammatory bowel disease treated with biologic drugs

BACKGROUND

Patients receiving biologic therapies are at risk for viral infections. This study investigated the impact of the SARS-CoV-2 infection and the serum prevalence of SARS-CoV-2 antibodies in patients with inflammatory bowel disease (IBD) treated with biologic drugs.

METHODS

Information on demography, co-morbidities, clinical data regarding IBD, symptoms suggestive of the SARS-CoV-2 infection, close contacts with SARS-CoV-2 positive patients, hospitalization, and therapies administered for COVID-19 was collected for all patients who were being treated with biologic drugs. All patients underwent SARS-CoV-2 antibody testing.

RESULTS

Two hundred and fifty-nine patients (27 children) with a mean age of 42.2 ± 16.7 years (range 9 - 88) and a mean duration of disease of 13.4 ± 10 years (range 0.2 - 49) were enrolled. One hundred four patients (40.2%) had ulcerative colitis, and 155 (59.8%) had Crohn's disease. About the therapy: 62 patients were receiving infliximab, 89 adalimumab, 20 golimumab, 57 vedolizumab, 27 ustekinumab, 1 thalidomide, and 3 an experimental compound. The mean Charlson Comorbidity Index was 2. Thirty-two patients (12.3%) reported respiratory symptoms, and 2 of them were hospitalized (0.77%). Two patients resulted positive for IgG against SARS-CoV-2 (0.77%).

CONCLUSIONS

In patients with IBD, treatment with biologic drug does not represent a risk factor for the SARS-CoV-2 infection.

Genomewide Association Study of Severe Covid-19 with Respiratory Failure

BACKGROUND

There is considerable variation in disease behavior among patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (Covid-19). Genomewide association analysis may allow for the identification of potential genetic factors involved in the development of Covid-19.

METHODS

We conducted a genomewide association study involving 1980 patients with Covid-19 and severe disease (defined as respiratory failure) at seven hospitals in the Italian and Spanish epicenters of the SARS-CoV-2 pandemic in Europe. After quality control and the exclusion of population outliers, 835 patients and 1255 control participants from Italy and 775 patients and 950 control participants from Spain were included in the final analysis. In total, we analyzed 8,582,968 single-nucleotide polymorphisms and conducted a meta-analysis of the two case-control panels.

RESULTS

We detected cross-replicating associations with rs11385942 at locus 3p21.31 and with rs657152 at locus 9q34.2, which were significant at the genomewide level (P<5×10-8) in the meta-analysis of the two case-control panels (odds ratio, 1.77; 95% confidence interval [CI], 1.48 to 2.11; P = 1.15×10-10; and odds ratio, 1.32; 95% CI, 1.20 to 1.47; P = 4.95×10-8, respectively). At locus 3p21.31, the association signal spanned the genes SLC6A20, LZTFL1, CCR9, FYCO1, CXCR6 and XCR1. The association signal at locus 9q34.2 coincided with the ABO blood group locus; in this cohort, a blood-group-specific analysis showed a higher risk in blood group A than in other blood groups (odds ratio, 1.45; 95% CI, 1.20 to 1.75; P = 1.48×10-4) and a protective effect in blood group O as compared with other blood groups (odds ratio, 0.65; 95% CI, 0.53 to 0.79; P = 1.06×10-5).

CONCLUSIONS

We identified a 3p21.31 gene cluster as a genetic susceptibility locus in patients with Covid-19 with respiratory failure and confirmed a potential involvement of the ABO blood-group system. (Funded by Stein Erik Hagen and others.).

microRNA-mRNA network model in patients with achalasia

BACKGROUND

Achalasia is a rare idiopathic disease with a complex etio-pathogenesis still unknown. This study aimed to identify microRNA (miRNA)-mRNA regulatory networks underlying achalasia.

METHODS

The investigation was performed in tissue specimens from 11 patients and five controls using the microarray technology followed by an integrated bioinformatics analysis.

KEY RESULTS

One hundred and six miRNAs were significantly up-regulated and 64 were down-regulated in achalasia patients. The expression of the most 10 differential expressed miRNAs (miR-122-5p, miR-133a-3p, miR-504-5p, miR-187-3p, miR-133b, miR-200c-3p, miR-375, miR-200b-5p, miR-200b-3p, and miR203a) was confirmed by droplet digital PCR in an independent cohort. The interactions between the significant miRNAs and their targets uncovered 14 miRNA-mRNA interacting pairs with experimentally predicted genes (ie, FN1, ROCK2, DPYSL2), and 35 pairs with not experimentally target genes (ie, SULF1, MRVI1, PRKG1); all genes were involved in immune cell trafficking, skeletal and muscular system development, nervous system development macro-processes.

CONCLUSION & INFERENCES

The mRNA-miRNA regulatory networks described in this study provide new insights in the genetic background of the disease, suggesting further investigations in novel pathogenic mechanisms.

Plasma N-Glycan Signatures Are Associated With Features of Inflammatory Bowel Diseases

BACKGROUND & AIMS

Biomarkers are needed for early detection of Crohn's disease (CD) and ulcerative colitis (UC) or to predict patient outcomes. Glycosylation is a common and complex posttranslational modification of proteins that affects their structure and activity. We compared plasma N-glycosylation profiles between patients with CD or UC and healthy individuals (controls).

METHODS

We analyzed the total plasma N-glycomes of 2635 patients with inflammatory bowel diseases and 996 controls by mass spectrometry with a linkage-specific sialic acid derivatization technique. Plasma samples were acquired from 2 hospitals in Italy (discovery cohort, 1989 patients with inflammatory bowel disease [IBD] and 570 controls) and 1 medical center in the United States (validation cohort, 646 cases of IBD and 426 controls). Sixty-three glycoforms met our criteria for relative quantification and were extracted from the raw data with the software MassyTools. Common features shared by the glycan compositions were combined in 78 derived traits, including the number of antennae of complex-type glycans and levels of fucosylation, bisection, galactosylation, and sialylation. Associations of plasma N-glycomes with age, sex, CD, UC, and IBD-related parameters such as disease location, surgery and medication, level of C-reactive protein, and sedimentation rate were tested by linear and logistic regression.

RESULTS

Plasma samples from patients with IBD had a higher abundance of large-size glycans compared with controls, a decreased relative abundance of hybrid and high-mannose structures, lower fucosylation, lower galactosylation, and higher sialylation (α2,3- and α2,6-linked). We could discriminate plasma from patients with CD from that of patients with UC based on higher bisection, lower galactosylation, and higher sialylation (α2,3-linked). Glycosylation patterns were associated with disease location and progression, the need for a more potent medication, and surgery. These results were replicated in a large independent cohort.

CONCLUSIONS

We performed high-throughput analysis to compare total plasma N-glycomes of individuals with vs without IBD and to identify patterns associated with disease features and the need for treatment. These profiles might be used in diagnosis and for predicting patients' responses to treatment.

Female-Specific Association Between Variants on Chromosome 9 and Self-Reported Diagnosis of Irritable Bowel Syndrome

BACKGROUND & AIMS

Genetic factors are believed to affect risk for irritable bowel syndrome (IBS), but there have been no sufficiently powered and adequately sized studies. To identify DNA variants associated with IBS risk, we performed a genome-wide association study (GWAS) of the large UK Biobank population-based cohort, which includes genotype and health data from 500,000 participants.

METHODS

We studied 7,287,191 high-quality single nucleotide polymorphisms in individuals who self-reported a doctor's diagnosis of IBS (cases; n = 9576) compared to the remainder of the cohort (controls; n = 336,499) (mean age of study subjects, 40-69 years). Genome-wide significant findings were further investigated in 2045 patients with IBS from tertiary centers and 7955 population controls from Europe and the United States, and a small general population sample from Sweden (n = 249). Functional annotation of GWAS results was carried out by integrating data from multiple biorepositories to obtain biological insights from the observed associations.

RESULTS

We identified a genome-wide significant association on chromosome 9q31.2 (single nucleotide polymorphism rs10512344; P = 3.57 × 10-8) in a region previously linked to age at menarche, and 13 additional loci of suggestive significance (P < 5.0×10-6). Sex-stratified analyses revealed that the variants at 9q31.2 affect risk of IBS in women only (P = 4.29 × 10-10 in UK Biobank) and also associate with constipation-predominant IBS in women (P = .015 in the tertiary cohort) and harder stools in women (P = .0012 in the population-based sample). Functional annotation of the 9q31.2 locus identified 8 candidate genes, including the elongator complex protein 1 gene (ELP1 or IKBKAP), which is mutated in patients with familial dysautonomia.

CONCLUSIONS

In a sufficiently powered GWAS of IBS, we associated variants at the locus 9q31.2 with risk of IBS in women. This observation may provide additional rationale for investigating the role of sex hormones and autonomic dysfunction in IBS.

Glycosylation of Immunoglobulin G Associates With Clinical Features of Inflammatory Bowel Diseases

BACKGROUND AND AIMS

Causes of inflammatory bowel diseases are not well understood and the most prominent forms, Crohn's disease (CD) and ulcerative colitis (UC), are sometimes hard to distinguish. Glycosylation of IgG has been associated with CD and UC. IgG Fc-glycosylation affects IgG effector functions. We evaluated changes in IgG Fc-glycosylation associated with UC and CD, as well as with disease characteristics in different patient groups.

METHODS

We analyzed 3441 plasma samples obtained from 2 independent cohorts of patients with CD (874 patients from Italy and 391 from the United States) or UC (1056 from Italy and 253 from the US and healthy individuals [controls]; 427 in Italy and 440 from the United States). IgG Fc-glycosylation (tryptic glycopeptides) was analyzed by liquid chromatography coupled to mass spectrometry. We analyzed associations between disease status (UC vs controls, CD vs controls, and UC vs CD) and glycopeptide traits, and associations between clinical characteristics and glycopeptide traits, using a logistic regression model with age and sex included as covariates.

RESULTS

Patients with CD or UC had lower levels of IgG galactosylation than controls. For example, the odds ratio (OR) for IgG1 galactosylation in patients with CD was 0.59 (95% confidence interval [CI], 0.51-0.69) and for patients with UC was 0.81 (95% CI, 0.71-0.92). Fucosylation of IgG was increased in patients with CD vs controls (for IgG1: OR, 1.27; 95% CI, 1.12-1.44), but decreased in patients with UC vs controls (for IgG23: OR, 0.72; 95% CI, 0.63-0.82). Decreased galactosylation associated with more severe CD or UC, including the need for surgery in patients with UC vs controls (for IgG1: OR, 0.69; 95% CI, 0.54-0.89) and in patients with CD vs controls (for IgG23: OR, 0.78; 95% CI, 0.66-0.91).

CONCLUSIONS

In a retrospective analysis of plasma samples from patients with CD or UC, we associated levels of IgG Fc-glycosylation with disease (compared to controls) and its clinical features. These findings could increase our understanding of mechanisms of CD and UC pathogenesis and be used to develop diagnostics or guide treatment.

Do pancreatic cancer and chronic pancreatitis share the same genetic risk factors? A PANcreatic Disease ReseArch (PANDoRA) consortium investigation

Pancreatic ductal adenocarcinoma (PDAC) is a very aggressive tumor with a five-year survival of less than 6%. Chronic pancreatitis (CP), an inflammatory process in of the pancreas, is a strong risk factor for PDAC. Several genetic polymorphisms have been discovered as susceptibility loci for both CP and PDAC. Since CP and PDAC share a consistent number of epidemiologic risk factors, the aim of this study was to investigate whether specific CP risk loci also contribute to PDAC susceptibility. We selected five common SNPs (rs11988997, rs379742, rs10273639, rs2995271 and rs12688220) that were identified as susceptibility markers for CP and analyzed them in 2,914 PDAC cases, 356 CP cases and 5,596 controls retrospectively collected in the context of the international PANDoRA consortium. We found a weak association between the minor allele of the PRSS1-PRSS2-rs10273639 and an increased risk of developing PDAC (ORhomozygous  = 1.19, 95% CI 1.02-1.38, p = 0.023). Additionally all the SNPs confirmed statistically significant associations with risk of developing CP, the strongest being PRSS1-PRSS2-rs10273639 (ORheterozygous  = 0.51, 95% CI 0.39-0.67, p = 1.10 × 10-6 ) and MORC4-rs 12837024 (ORhomozygous  = 2.07 (1.55-2.77, ptrend  = 0.7 × 10-11 ). Taken together, the results from our study do not support variants rs11988997, rs379742, rs10273639, rs2995271 and rs12688220 as strong predictors of PDAC risk, but further support the role of these SNPs in CP susceptibility. Our study suggests that CP and PDAC probably do not share genetic susceptibility, at least in terms of high frequency variants.

Inflammatory Bowel Disease Meets Systems Biology: A Multi-Omics Challenge and Frontier

The inflammatory bowel disease (IBD) is a systemic disease that is characterized by the inflammation of the gastrointestinal tract. It includes ulcerative colitis and the Crohn's disease. Presently, IBD is one of the most investigated common complex human disorders, although its causes remain unclear. Multi-omics mechanisms involving genomic, transcriptomic, proteomic, and epigenomic variations, not to forget the miRNome, together with environmental contributions, result in an impairment of the immune system in persons with IBD. Such interactions at multiple levels of biology and in concert with the environment constitute the actual engine of this complex disease, demanding a multifactorial and multi-omics perspective to better understand the root causes of IBD. This expert analysis reviews and examines the latest literature and underscores, from the perspective of systems biology, the value of multi-omics technologies as opportunities to unravel the "IBD integrome." We anticipate that multi-omics research will accelerate the new discoveries and insights on IBD in the near future. It shall also pave the way for early diagnosis and help clinicians and families with IBD to forecast and make informed decisions about the prognosis and, possibly, personalized therapeutics in the future.

Crohn's Colitis: Development of a multiplex gene expression assay comparing mRNA levels of susceptibility genes

Crohn's disease (CD) is a multifactorial immunologically mediated disease. In this study we explored, for the first time, the efficacy of the Multiplex Gene Assay technology for detecting mRNA expression profile of 24 selected CD related genes in endoscopic biopsies and surgical specimens from CD patients with colonic localization of the disease. The polymorphisms of genes most frequently associated with CD were also analysed in DNA samples from the same patients. The analysis of endoscopic samples showed increased expression of 7 genes in inflamed mucosa compared to non-inflamed mucosa and suggests the activation of the autophagy process and of a Th17 adaptive response. The analysis of surgical specimens showed increased expression of 16 genes in inflamed tissue compared to non-inflamed internal controls and revealed the activation of immune-adaptive Th17 response in association with a Th1 response. Furthermore, an increased expression of genes involved in ionic transport and signal transduction was found in inflamed mucosa compared to non-inflamed internal controls. This study confirms the activation of Th17 and Th1 adaptive-immune response also in colonic CD. It should be stressed that these responses have been disclosed in biopsy tissue, while only Th17 differentiation is revealed in endoscopic tissue. Interestingly, the polymorphisms analysis revealed that a homozygous genotype is associated to a more complicated clinical course.

Functional Implications of MicroRNAs in Crohn's Disease Revealed by Integrating MicroRNA and Messenger RNA Expression Profiling

Crohn's disease (CD) is a debilitating inflammatory bowel disease (IBD) that emerges due to the influence of genetic and environmental factors. microRNAs (miRNAs) have been identified in the tissue and sera of IBD patients and may play an important role in the induction of IBD. Our study aimed to identify differentially expressed miRNAs and miRNAs with the ability to alter transcriptome activity by comparing inflamed tissue samples with their non-inflamed counterparts. We studied changes in miRNA-mRNA interactions associated with CD by examining their differential co-expression relative to normal mucosa from the same patients. Correlation changes between the two conditions were incorporated into scores of predefined gene sets to identify biological processes with altered miRNA-mediated control. Our study identified 28 miRNAs differentially expressed (p-values < 0.01), of which 14 are up-regulated. Notably, our differential co-expression analysis highlights microRNAs (i.e., miR-4284, miR-3194 and miR-21) that have known functional interactions with key mechanisms implicated in IBD. Most of these miRNAs cannot be detected by differential expression analysis that do not take into account miRNA-mRNA interactions. The identification of differential miRNA-mRNA co-expression patterns will facilitate the investigation of the miRNA-mediated molecular mechanisms underlying CD pathogenesis and could suggest novel drug targets for validation.

Crohn's Disease Localization Displays Different Predisposing Genetic Variants

Background

Crohn’s disease (CD) is a pathologic condition with different clinical expressions that may reflect an interplay between genetics and environmental factors. Recently, it has been highlighted that three genetic markers, NOD2, MHC and MST1, were associated to distinct CD sites, supporting the concept that genetic variations may contribute to localize CD. Genetic markers, previously shown to be associated with inflammatory bowel disease (IBD), were tested in CD patients with the aim to better dissect the genetic relationship between ileal, ileocolonic and colonic CD and ascertain whether a different genetic background would support the three disease sites as independent entities.

Methods

A panel of 29 SNPs of 19 IBD loci were analyzed by TaqMan SNP allelic discrimination method both evaluating their distinct contribute and analyzing all markers jointly.

Results

Seven hundred and eight CD patients and 537 healthy controls were included in the study. Of the overall population of patients, 237 patients had an ileal involvement (L1), 171 a colonic localization (L2), and the 300 remaining an ileocolon location (L3). We confirmed the association for 23 of 29 variations (P < 0.05). Compared to healthy controls, 16 variations emerged as associated to an ileum disease, 7 with a colonic disease and 14 with an ileocolonic site (P < 0.05). Comparing ileum to colonic CD, 5 SNPs (17%) were differentially associated (P < 0.05). A genetic model score that aggregated the risks of 23 SNPs and their odds ratios (ORs), yielded an Area Under the Curve (AUC) of 0.70 for the overall CD patients. By analyzing each CD location, the AUC remained at the same level for the ileal and ileocolonic sites (0.73 and 0.72, respectively), but dropped to a 0,66 value in patients with colon localization.

Conclusions

Our findings reaffirm the existence of at least three different subgroups of CD patients, with a genetic signature distinctive for the three main CD sites.

Metabolomic profile in pancreatic cancer patients: a consensus-based approach to identify highly discriminating metabolites

Purpose

pancreatic adenocarcinoma is the fourth leading cause of cancer related deaths due to its aggressive behavior and poor clinical outcome. There is a considerable variability in the frequency of serum tumor markers in cancer' patients. We performed a metabolomics screening in patients diagnosed with pancreatic cancer.

Experimental Design

Two targeted metabolomic assays were conducted on 40 serum samples of patients diagnosed with pancreatic cancer and 40 healthy controls. Multivariate methods and classification trees were performed.

Materials and Methods

Sparse partial least squares discriminant analysis (SPLS-DA) was used to reduce the high dimensionality of a pancreatic cancer metabolomic dataset, differentiating between pancreatic cancer (PC) patients and healthy subjects. Using Random Forest analysis palmitic acid, 1,2-dioleoyl-sn-glycero-3-phospho-rac-glycerol, lanosterol, lignoceric acid, 1-monooleoyl-rac-glycerol, cholesterol 5α,6α epoxide, erucic acid and taurolithocholic acid (T-LCA), oleoyl-L-carnitine, oleanolic acid were identified among 206 metabolites as highly discriminating between disease states. Comparison between Receiver Operating Characteristic (ROC) curves for palmitic acid and CA 19-9 showed that the area under the ROC curve (AUC) of palmitic acid (AUC=1.000; 95% confidence interval) is significantly higher than CA 19-9 (AUC=0.963; 95% confidence interval: 0.896-1.000).

Conclusion

Mass spectrometry-based metabolomic profiling of sera from pancreatic cancer patients and normal subjects showed significant alterations in the profiles of the metabolome of PC patients as compared to controls. These findings offer an information-rich matrix for discovering novel candidate biomarkers with diagnostic or prognostic potentials.

Systematic analysis of circadian genes using genome-wide cDNA microarrays in the inflammatory bowel disease transcriptome

Simultaneous analysis of the transcripts of thousands of genes by cDNA microarrays allows the identification of genetic regulatory mechanisms involved in disease pathophysiology. The circadian clock circuitry controls essential cell processes and the functioning of organ systems, which are characterized by rhythmic variations with 24-hour periodicity. The derangement of these processes is involved in the basic mechanisms of inflammatory, metabolic, degenerative and neoplastic diseases. We evaluated by genome-wide cDNA microarray analysis the transcriptome of endoscopic mucosal biopsies of patients with inflammatory bowel diseases (IBD) focusing on the expression of circadian genes in Crohn's disease (CD) and ulcerative colitis (UC). Twenty-nine IBD patients (15 with CD and 14 with UC) were enrolled and mucosal biopsies were sampled at either inflamed or adjacent non-inflamed areas of the colon. A total of 150 circadian genes involved in pathways controlling crucial cell processes and tissue functions were investigated. In CD specimens 50 genes were differentially expressed, and 21 genes resulted up-regulated when compared to healthy colonic mucosa. In UC specimens 50 genes were differentially expressed, and 27 genes resulted up-regulated when compared to healthy colonic mucosa. Among the core clock genes ARNTL2 and RORA were up-regulated, while CSNK2B, NPAS2, PER1 and PER3 were down-regulated in CD specimens. Conversely, ARNTL2, CRY1, CSNK1E, RORA and TIPIN were up-regulated, while NR1D2 and PER3 were down-regulated in UC. In conclusion, in CD and UC patients there are differences in the expression of circadian genes between normal and diseased intestinal mucosa. The deregulated genes evidenced by transcriptome analysis in the major IBDs may play a crucial role in the pathophysiological mechanisms and may suggest novel therapeutic approaches.

Meta-analysis of shared genetic architecture across ten pediatric autoimmune diseases

Genome-wide association studies (GWASs) have identified hundreds of susceptibility genes, including shared associations across clinically distinct autoimmune diseases. We performed an inverse χ(2) meta-analysis across ten pediatric-age-of-onset autoimmune diseases (pAIDs) in a case-control study including more than 6,035 cases and 10,718 shared population-based controls. We identified 27 genome-wide significant loci associated with one or more pAIDs, mapping to in silico-replicated autoimmune-associated genes (including IL2RA) and new candidate loci with established immunoregulatory functions such as ADGRL2, TENM3, ANKRD30A, ADCY7 and CD40LG. The pAID-associated single-nucleotide polymorphisms (SNPs) were functionally enriched for deoxyribonuclease (DNase)-hypersensitivity sites, expression quantitative trait loci (eQTLs), microRNA (miRNA)-binding sites and coding variants. We also identified biologically correlated, pAID-associated candidate gene sets on the basis of immune cell expression profiling and found evidence of genetic sharing. Network and protein-interaction analyses demonstrated converging roles for the signaling pathways of type 1, 2 and 17 helper T cells (TH1, TH2 and TH17), JAK-STAT, interferon and interleukin in multiple autoimmune diseases.

Variation in genes encoding for interferon λ-3 and λ-4 in the prediction of HCV-1 treatment-induced viral clearance

BACKGROUND & AIMS

In patients with chronic HCV-1 infection, recent evidences indicate that determination of a dinucleotide polymorphism (ss469415590, ΔG/TT) of a new gene, designated IFN λ-4, might be more accurate than the 12979860CC type of the IL28B locus in predicting sustained virological response (SVR) following peg-interferon and ribavirin. In addition, combined genotyping of different SNPs of the IL28B locus was shown to help dissect patients most prone to SVR among those with rs12979860CT. We examined whether single or combined genotyping of two IL28B SNPs, rs12979860 and rs8099917, and ss469415590 variation might improve the prediction of SVR.

RESULTS

In the study cohort of 539 patients, 38% had SVR. The SNPs 12979860CC, rs8099917TT, and rs469415590TT/TT correlated significantly with SVR (68%, 50%, and 67%). Carriers of either the triplotype rs12979860CC_ss469415590TT/TT_rs8099917TT or the diplotype rs12979860CC_ss469415590TT/TT had the highest SVR rate (72%). In carriers of the rs12979860 T allele, neither the rs8099917 nor the ss469415590 improved the response prediction. After pooling this finding with data from previous studies, in rs12979860 T heterozygous individuals the co-presence of the rs8099917TT SNP was associated with improved response prediction.

CONCLUSION

In HCV-1 patients, the rs12979860 polymorphism appeared as the hit SNP better predicting response following peg-interferon and ribavirin treatment. Additional ss469415590 or rs8099917 genotyping had no added benefit for response prediction. In the subset of carriers of the rs12979860 T allele, genotyping of the rs8099917 SNP was unhelpful in the present investigation, but may inform clinical prediction of treatment response when our data were pooled with previous investigations.

Genetic variation in the lymphotoxin-α (LTA)/tumour necrosis factor-α (TNFα) locus as a risk factor for idiopathic achalasia

BACKGROUND

Idiopathic achalasia is a rare motor disorder of the oesophagus characterised by neuronal loss at the lower oesophageal sphincter. Achalasia is generally accepted as a multifactorial disorder with various genetic and environmental factors being risk-associated. Since genetic factors predisposing to achalasia have been poorly documented, we assessed whether single nucleotide polymorphisms (SNPs) in genes mediating immune response and neuronal function contribute to achalasia susceptibility.

METHODS

391 SNPs covering 190 immune and 67 neuronal genes were genotyped in an exploratory cohort from Central Europe (589 achalasia patients, 794 healthy volunteers (HVs)). 24 SNPs (p<0.05) were validated in an Italian (160 achalasia patients, 278 HVs) and Spanish cohort (281 achalasia patients, 296 HVs). 16 SNPs in linkage disequilibrium (LD) with rs1799724 (r(2)>0.2) were genotyped in the exploratory cohort. Genotype distributions of patients (1030) and HVs (1368) were compared using Cochran-Armitage trend test.

RESULTS

The rs1799724 SNP located between the lymphotoxin-α (LTA) and tumour necrosis factor-α (TNFα) genes was significantly associated with achalasia and withstood correction for testing multiple SNPs (p=1.17E-4, OR=1.41 (1.18 to 1.67)). SNPs in high LD with rs1799724 were associated with achalasia. Three SNPs located in myosin-5B, adrenergic receptor-β-2 and interleukin-13 (IL13) showed nominally significant association to achalasia that was strengthened by replication.

CONCLUSIONS

Our study provides evidence for rs1799724 at the LTA/TNFα locus as a susceptibility factor for idiopathic achalasia. Additional studies are needed to dissect which genetic variants in the LTA/TNFα locus are disease-causing and confirm other variants as potential susceptibility factors for achalasia.

Common variants in the HLA-DQ region confer susceptibility to idiopathic achalasia

Idiopathic achalasia is characterized by a failure of the lower esophageal sphincter to relax due to a loss of neurons in the myenteric plexus. This ultimately leads to massive dilatation and an irreversibly impaired megaesophagus. We performed a genetic association study in 1,068 achalasia cases and 4,242 controls and fine-mapped a strong MHC association signal by imputing classical HLA haplotypes and amino acid polymorphisms. An eight-residue insertion at position 227-234 in the cytoplasmic tail of HLA-DQβ1 (encoded by HLA-DQB1*05:03 and HLA-DQB1*06:01) confers the strongest risk for achalasia (P=1.73×10(-19)). In addition, two amino acid substitutions in the extracellular domain of HLA-DQα1 at position 41 (lysine encoded by HLA-DQA1*01:03; P=5.60×10(-10)) and of HLA-DQβ1 at position 45 (glutamic acid encoded by HLA-DQB1*03:01 and HLA-DQB1*03:04; P=1.20×10(-9)) independently confer achalasia risk. Our study implies that immune-mediated processes are involved in the pathophysiology of achalasia.

Association between variants of PRDM1 and NDP52 and Crohn's disease, based on exome sequencing and functional studies

BACKGROUND & AIMS

Genome-wide association studies (GWAS) have identified 140 Crohn's disease (CD) susceptibility loci. For most loci, the variants that cause disease are not known and the genes affected by these variants have not been identified. We aimed to identify variants that cause CD through detailed sequencing, genetic association, expression, and functional studies.

METHODS

We sequenced whole exomes of 42 unrelated subjects with CD and 5 healthy subjects (controls) and then filtered single nucleotide variants by incorporating association results from meta-analyses of CD GWAS and in silico mutation effect prediction algorithms. We then genotyped 9348 subjects with CD, 2868 subjects with ulcerative colitis, and 14,567 control subjects and associated variants analyzed in functional studies using materials from subjects and controls and in vitro model systems.

RESULTS

We identified rare missense mutations in PR domain-containing 1 (PRDM1) and associated these with CD. These mutations increased proliferation of T cells and secretion of cytokines on activation and increased expression of the adhesion molecule L-selectin. A common CD risk allele, identified in GWAS, correlated with reduced expression of PRDM1 in ileal biopsy specimens and peripheral blood mononuclear cells (combined P = 1.6 × 10(-8)). We identified an association between CD and a common missense variant, Val248Ala, in nuclear domain 10 protein 52 (NDP52) (P = 4.83 × 10(-9)). We found that this variant impairs the regulatory functions of NDP52 to inhibit nuclear factor κB activation of genes that regulate inflammation and affect the stability of proteins in Toll-like receptor pathways.

CONCLUSIONS

We have extended the results of GWAS and provide evidence that variants in PRDM1 and NDP52 determine susceptibility to CD. PRDM1 maps adjacent to a CD interval identified in GWAS and encodes a transcription factor expressed by T and B cells. NDP52 is an adaptor protein that functions in selective autophagy of intracellular bacteria and signaling molecules, supporting the role of autophagy in the pathogenesis of CD.

Associations between genetic polymorphisms in IL-33, IL1R1 and risk for inflammatory bowel disease

BACKGROUND

Recent evidence suggests that the IL-33/IL1RL1 axis plays a critical role in several autoimmune and inflammatory disorders; however, its mechanistic role in inflammatory bowel disease (IBD) has not been clearly defined. We investigated the contribution of IL-33 and IL1RL1 polymorphisms to IBD risk, and possible correlations with phenotype in an Italian cohort of adult and pediatric patients.

METHODS

We evaluated the association of six SNPs in IL-33 and IL1RL1 genes, in 805 Crohn's disease (CD), 816 ulcerative colitis (UC), and 752 controls, using Taqman. IL-33 and IL1RL1 mRNA expression was also analyzed.

RESULTS

Significant allele and genotype associations with IL-33 rs3939286 were found in CD (P = 0.004; P = 0.035) and UC patients (P = 0.002; P = 0.038). After stratifying the cohort for age at diagnosis, the differences remained significant only in the IBD adult-onset. Significant associations were also obtained in CD patients with two IL1RL1 polymorphisms (rs13015714 and rs2058660, P<0.015). By combining homo- and heterozygous carriers of the rs13015714 risk allele, differences were still significant for both CD adult- and pediatric-onset. Upon genotype-phenotype evaluation, an increased frequency of extensive colitis in adult UC (P = 0.019) and in steroid-responsive pediatric patients (P = 0.024) carrying the IL-33 rs3939286 risk genotype, was observed. mRNA expression of IL-33 and IL1RL1 in inflamed IBD biopsy samples was significantly increased.

CONCLUSIONS

Common IL-33 and IL1RL1 polymorphisms contribute to the risk of IBD in an Italian cohort of adult and pediatric patients, with some influence on sub-phenotypes.

Host-microbe interactions have shaped the genetic architecture of inflammatory bowel disease

Crohn’s disease (CD) and ulcerative colitis (UC), the two common forms of inflammatory bowel disease (IBD), affect over 2.5 million people of European ancestry with rising prevalence in other populations¹. Genome-wide association studies (GWAS) and subsequent meta-analyses of CD and UC^2,3 as separate phenotypes implicated previously unsuspected mechanisms, such as autophagy⁴, in pathogenesis and showed that some IBD loci are shared with other inflammatory diseases⁵. Here we expand knowledge of relevant pathways by undertaking a meta-analysis of CD and UC genome-wide association scans, with validation of significant findings in more than 75,000 cases and controls. We identify 71 new associations, for a total of 163 IBD loci that meet genome-wide significance thresholds. Most loci contribute to both phenotypes, and both directional and balancing selection effects are evident. Many IBD loci are also implicated in other immune-mediated disorders, most notably with ankylosing spondylitis and psoriasis. We also observe striking overlap between susceptibility loci for IBD and mycobacterial infection. Gene co-expression network analysis emphasizes this relationship, with pathways shared between host responses to mycobacteria and those predisposing to IBD.

The expression of leucine-rich repeat gene family members in colorectal cancer

This study was conducted to evaluate the association of the leucine-rich repeat (LRR) gene family with colorectal cancer (CRC). The expression of members of the LRR gene family were analyzed in 17 CRC specimens and in 59 healthy colorectal tissues by using Human Exon1.0ST microarray, and in 25 CRC specimens and 32 healthy colorectal tissues by U133Plus2.0 microarray. An association was found for 25 genes belonging to the plant-specific (PS) class of LRR genes (P = 0.05 for Exon1.0 ST and P = 0.04 for U133Plus2.0). In both data-sets, in CRC, we found down-regulation of SHOC2 (P < 0.00003) and LRRC28 (P < 0.01) and up-regulation of LRSAM1 (P < 0.000001), while up-regulation of MFHAS1 (P = 0.0005) and down-regulation of WDFY3 (P = 0.026) were found only in the Exon1.0 ST data-set. The PS LLR gene class encodes proteins that activate immune cells and might play a key role in programmed cell death and autophagy. SHOC2 and LRRC28 genes involved in RAS-mediated signaling, which hinders nutrient deprivation-induced autophagy, might be a possible link between the negative control of autophagy and tumorigenesis.

Association study of a polymorphism in clock gene PERIOD3 and risk of inflammatory bowel disease

Altered body rhythmicity and deregulated clock gene expression may cause circadian disruption, which can lead to immune dysregulation and chronic inflammatory diseases. PERIOD3 (PER3) polymorphisms have been associated with circadian disruption and changed secretion of cytokines involved in chronic inflammation. Crohn's disease (CD) and ulcerative colitis (UC) are multifactorial diseases resulting from complex interaction among environmental/microbial factors and the intestinal immune system, triggering an abnormal immune response in genetically susceptible individuals. We evaluated the influence of a polymorphism of the clock gene PER3 on susceptibility and behavior of these inflammatory bowel diseases. The rs2797685 variant of the PER3 gene was assessed in 1082 CD and 972 UC patients, 754 of whom had been diagnosed <18 yrs of age, and 1311 unrelated healthy controls. Allele and genotype frequencies of rs2797685 were significantly increased in both CD (p = 1.6 × 10(-4), odds ratio [OR] = 1.38, 95% confidence interval [CI]: 1.17-1.63) and UC (p = .012, OR = 1.25, 95% CI: 1.05-1.48) patients. Difference between frequency distributions remained statistically significant after stratifying the cohort according to age at diagnosis for CD, but not for UC. Statistically significant association was found between PER3 polymorphism and use of immunosuppressive drugs in pediatric CD patients (p < .001) and with stricturing and fistulizing disease behavior in adult CD patients (p = .031). In conclusion, results of this association study suggest a possible role of PER3 polymorphism in determining susceptibility to CD and UC and phenotypic characteristics of CD. In particular, the rs2797685 variant of the PER3 gene is associated with a more aggressive form of CD, highlighted by higher use of immunosuppressants and more frequent stricturing and fistulizing disease behaviors, as well as early onset of CD. This is a descriptive study, and functional data are needed to prove a causal relationship; nonetheless, involvement of the clock gene machinery in the susceptibility and the behavior of inflammatory bowel diseases may suggest new pathophysiological mechanisms and new therapeutic approaches.

Genetics and ulcerative colitis: what are the clinical implications?

Substantial progress has been made in the last years in characterizing the susceptibility genes involved in IBD pathogenesis, especially for Crohn's disease. Although some genetic factors associated with Crohn's disease also predispose individuals to ulcerative colitis, markers specific only for ulcerative colitis have been found. Recent genome-wide association studies in ulcerative colitis have identified several new loci, and suggested many new potential pathways. The identified susceptibility genes and their variants could be useful to predict disease course and to improve stratification of patients, when correlated with other subphenotypes. Moreover, understanding the biological pathways involved in the disease could lead to the development of new treatments and molecules that specifically target such pathways, discover different therapeutic approaches and eventually progress to personalized treatment.

Deep resequencing of GWAS loci identifies independent rare variants associated with inflammatory bowel disease

More than 1,000 susceptibility loci have been identified through genome-wide association studies (GWAS) of common variants; however, the specific genes and full allelic spectrum of causal variants underlying these findings have not yet been defined. Here we used pooled next-generation sequencing to study 56 genes from regions associated with Crohn's disease in 350 cases and 350 controls. Through follow-up genotyping of 70 rare and low-frequency protein-altering variants in nine independent case-control series (16,054 Crohn's disease cases, 12,153 ulcerative colitis cases and 17,575 healthy controls), we identified four additional independent risk factors in NOD2, two additional protective variants in IL23R, a highly significant association with a protective splice variant in CARD9 (P < 1 × 10(-16), odds ratio ≈ 0.29) and additional associations with coding variants in IL18RAP, CUL2, C1orf106, PTPN22 and MUC19. We extend the results of successful GWAS by identifying new, rare and probably functional variants that could aid functional experiments and predictive models.

Discovering genetic variants in Crohn's disease by exploring genomic regions enriched of weak association signals

BACKGROUND

A meta-analysis has re-analysed previous genome-wide association scanning definitively confirming eleven genes and further identifying 21 new loci. However, the identified genes/loci still explain only the minority of genetic predisposition of Crohn's disease.

AIMS

To identify genes weakly involved in disease predisposition by analysing chromosomal regions enriched of single nucleotide polymorphisms with modest statistical association.

METHODS

We utilized the WTCCC data set evaluating 1748 CD and 2938 controls. The identification of candidate genes/loci was performed by a two-step procedure: first of all chromosomal regions enriched of weak association signals were localized; subsequently, weak signals clustered in gene regions were identified. The statistical significance was assessed by non parametric permutation tests.

RESULTS

The cytoband enrichment analysis highlighted 44 regions (P≤0.05) enriched with single nucleotide polymorphisms significantly associated with the trait including 23 out of 31 previously confirmed and replicated genes. Importantly, we highlight further 20 novel chromosomal regions carrying approximately one hundred genes/loci with modest association. Amongst these we find compelling functional candidate genes such as MAPT, GRB2 and CREM, LCT, and IL12RB2.

CONCLUSION

Our study suggests a different statistical perspective to discover genes weakly associated with a given trait, although further confirmatory functional studies are needed.

Glucocorticoid resistance in Crohn's disease and ulcerative colitis: an association study investigating GR and FKBP5 gene polymorphisms

The aim of this study is to investigate the role of single-nucleotide polymorphisms (SNPs) of the glucocorticoid receptor (GR) and of the related co-chaperone FKBP5 genes in the development of glucocorticoid (GC) resistance in Crohn's disease (CD) and ulcerative colitis (UC) patients. We have developed a high-resolution DNA melting method that allows simultaneous identification of GR (BclI, N363S and ER22/23EK) and FKBP5 (rs3800373, rs1360780 and rs4713916) polymorphisms. Genotype frequencies were determined in 100 consecutive CD and 100 UC patients under GCs therapy (50 responders and 50 resisters). The variation of FKBP5 polymorphism rs4713916 (G/A), in the putative promoter region of FKBP5, is significantly associated with resistance to GC treatment in CD (responder=17% versus resister=35%; P=0.0043). No significant differences were found in UC patients. If these preliminary findings will be confirmed, the combination of GR and FKBP5 mutational analyses could help to identify subgroups of CD patients with higher chances to benefit from GC treatment.

Genome-wide expression profiling identifies an impairment of negative feedback signals in the Crohn's disease-associated NOD2 variant L1007fsinsC

NOD2 is an intracellular receptor for the bacterial cell wall component muramyl dipeptide (MDP), and variants of NOD2 are associated with chronic inflammatory diseases of barrier organs (e.g., Crohn's disease, asthma, and atopic eczema). It is known that activation of NOD2 induces a variety of inflammatory and antibacterial factors. The exact transcriptomal signatures that define the cellular programs downstream of NOD2 activation and the influence of the Crohn-associated variant L1007fsinsC are yet to be defined. To describe the MDP-induced activation program, we analyzed the transcriptomal reactions of isogenic HEK293 cells expressing NOD2(wt) or NOD2(L1007fsinsC) to stimulation with MDP. Importantly, a clear loss of function could be observed in the cells carrying the Crohn-associated variant L1007fsinsC, whereas the NOD2(wt) cells showed differential regulation of growth factors, chemokines, and several antagonists of NF-κB (e.g., TNFAIP3 [A20] and IER3). This genotype-dependent regulation pattern was confirmed in primary human myelomonocytic cells. The influence of TNFAIP3 and IER3 in the context of NOD2 signaling was characterized, and we could validate the predicted role as inhibitors of NOD2-induced NF-κB activation. We show that IER3 impairs the protective effect of NOD2(wt) against bacterial cytoinvasion. These results further our understanding of NOD2 as a first-line defense molecule and emphasize the importance of simultaneous upregulation of counterregulatory anti-inflammatory factors as an integral part of the NOD2-induced cellular program. Lack of these regulatory events due to the L1007fsinsC variant may pivotally contribute to the induction and perpetuation of chronic inflammation.