The relationship between extreme inter-individual variation in macrophage gene expression and genetic susceptibility to inflammatory bowel disease.

The differentiation of resident intestinal macrophages from blood monocytes depends upon signals from the macrophage colony-stimulating factor receptor (CSF1R). Analysis of genome-wide association studies (GWAS) indicates that dysregulation of macrophage differentiation and response to microorganisms contributes to susceptibility to chronic inflammatory bowel disease (IBD). Here, we analyzed transcriptomic variation in monocyte-derived macrophages (MDM) from affected and unaffected sib pairs/trios from 22 IBD families and 6 healthy controls. Transcriptional network analysis of the data revealed no overall or inter-sib distinction between affected and unaffected individuals in basal gene expression or the temporal response to lipopolysaccharide (LPS). However, the basal or LPS-inducible expression of individual genes varied independently by as much as 100-fold between subjects. Extreme independent variation in the expression of pairs of HLA-associated transcripts (HLA-B/C, HLA-A/F and HLA-DRB1/DRB5) in macrophages was associated with HLA genotype. Correlation analysis indicated the downstream impacts of variation in the immediate early response to LPS. For example, variation in early expression of IL1B was significantly associated with local SNV genotype and with subsequent peak expression of target genes including IL23A, CXCL1, CXCL3, CXCL8 and NLRP3. Similarly, variation in early IFNB1 expression was correlated with subsequent expression of IFN target genes. Our results support the view that gene-specific dysregulation in macrophage adaptation to the intestinal milieu is associated with genetic susceptibility to IBD.

Comparative genomics and phenotypic studies to determine site-specificity of Escherichia coli in the lower gastrointestinal tract of humans.

Escherichia coli (E. coli) is an important commensal in the human gut; however, it is unknown whether strains show site-specificity in the lower gut. To investigate this, we assessed genotypic and phenotypic differences in 37 clone pairs (two strains with very similar multiple locus variable-number-tandem-repeat analysis [MLVA] profiles) of E. coli isolated from mucosal biopsies of two different gut locations (terminal ileum and rectum). The clone pairs varied at the genomic level; single nucleotide polymorphisms (SNPs) were common, multiple nucleotide polymorphisms (MNPs) were observed but less common, and few indels (insertions and deletions) were detected. The variation was higher in clone pairs that are associated with non-human-associated sequence types (ST) compared to human-associated STs, such as ST95, ST131, and ST73. No gene(s) with non-synonymous mutations were found to be commonly associated with either the terminal ileum or the rectal strains. At the phenotypic level, we identified the metabolic signatures for some STs. Rectum strains of some STs showed consistently higher metabolic activity with particular carbon sources. Clone pairs belonging to specific STs showed distinct growth patterns under different pH conditions. Overall, this study showed that E. coli may exhibit genomic and phenotypic variability at different locations in the gut. Although genomics did not reveal significant information suggesting the site-specificity of strains, some phenotypic studies have suggested that strains may display site-specificity in the lower gut. These results provide insights into the nature and adaptation of E. coli in the lower gut of humans. To the best of our knowledge, no study has investigated or demonstrated the site-specificity of commensal E. coli in the human gut.

Australia IBD Microbiome (AIM) Study: protocol for a multicentre longitudinal prospective cohort study.

INTRODUCTION: Crohn's disease and ulcerative colitis are common chronic idiopathic inflammatory bowel diseases (IBD), which cause considerable morbidity. Although the precise mechanisms of disease remain unclear, evidence implicates a strong multidirectional interplay between diet, environmental factors, genetic determinants/immune perturbations and the gut microbiota. IBD can be brought into remission using a number of medications, which act by suppressing the immune response. However, none of the available medications address any of the underlying potential mechanisms. As we understand more about how the microbiota drives inflammation, much interest has focused on identifying microbial signals/triggers in the search for effective therapeutic targets. We describe the establishment of the Australian IBD Microbiota (AIM) Study, Australia's first longitudinal IBD bioresource, which will identify and correlate longitudinal microbial and metagenomics signals to disease activity as evaluated by validated clinical instruments, patient-reported surveys, as well as biomarkers. The AIM Study will also gather extensive demographic, clinical, lifestyle and dietary data known to influence microbial composition in order to generate a more complete understanding of the interplay between patients with IBD and their microbiota. METHODS: The AIM Study is an Australian multicentre longitudinal prospective cohort study, which will enrol 1000 participants; 500 patients with IBD and 500 healthy controls over a 5-year period. Assessment occurs at 3 monthly intervals over a 24-month period. At each assessment oral and faecal samples are self-collected along with patient-reported outcome measures, with clinical data also collected at baseline, 12 and 24 months. Intestinal tissue will be sampled whenever a colonoscopy is performed. Dietary intake, general health and psychological state will be assessed using validated self-report questionnaires. Samples will undergo metagenomic, transcriptomic, proteomic, metabolomic and culturomic analyses. Omics data will be integrated with clinical data to identify predictive biomarkers of response to therapy, disease behaviour and environmental factors in patients with IBD. ETHICS AND DISSEMINATION: Ethical approval for this study has been obtained from the South Eastern Sydney Local Health District Research Ethics Committee (HREC 2019/ETH11443). Findings will be reported at national and international gastroenterology meetings and published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: ACTRN12619000911190.

Psychological distress is highly prevalent in inflammatory bowel disease: A survey of psychological needs and attitudes.

BACKGROUND AND AIM: Data on patient needs and access to psychological services in inflammatory bowel disease (IBD) are scarce. This study aimed to describe the levels of distress and the needs, attitudes, and access to psychological services for people within Australia against established Australian IBD Standards. METHODS: An online cross-sectional survey was conducted with Australians ≥16 years old recruited via Crohn's & Colitis Australia membership, public and private clinics, and the Royal Flying Doctor Service. K10 was used to measure psychological distress. The Chi-square test was used to compare those with and without distress on key variables. RESULTS: Overall, 731 respondents provided complete data (71.5% female, mean age 46.5 years). Overall, 50% of respondents reported distress; only 15.2% were currently seeing a mental health practitioner; only 16.1% were asked about their mental health by their IBD specialist or IBD nurse; and only 12.2% reported access to a mental health practitioner as part of their IBD service. Those with psychological distress were significantly less satisfied with their IBD care; more commonly hospitalized; had an active disease, fistula or perianal disease, pain, or fatigue; and were receiving steroids, opioids, or antidepressants (all P < 0.05). As many as 68.2% of those with severe distress were not seeing a mental health practitioner. CONCLUSIONS: The integrated biopsychosocial model of health care, with regular mental health screening and good access to mental health professionals, is requested by people living with IBD to improve their outcomes.

Quality of care in inflammatory bowel disease: actual health service experiences fall short of the standards.

BACKGROUND: Quality of care in inflammatory bowel disease (IBD) has received much attention internationally; however, the available surveys focus on health professionals rather than patients. AIMS: To assess the experiences of healthcare for people living with IBD against established Australian IBD Standards. METHODS: An online cross-sectional survey was conducted with Australians ≥16 years old recruited via Crohn's & Colitis Australia membership, public and private clinics and the Royal Flying Doctor Service. Participants completed a questionnaire incorporating items addressing the Australian IBD Standards 2016, the Picker Patient Experience Questionnaire, IBD Control Survey and the Manitoba Index. RESULTS: Complete data were provided by 731 respondents (71.5% female, median age 46 years, ranging from 16 to 84 years). While the majority (74.8%) were satisfied with their IBD healthcare, the care reported did not meet the Australian IBD Standards. Overall, 32.4% had access to IBD nurses, 30.9% to a dietician and 12% to a psychologist in their treating team. Participants managed by public IBD clinics were most likely to have access to an IBD nurse (83.7%), helpline (80.7%) and research trials (37%). One third of respondents reported waiting >14 days to see a specialist when their IBD flared. Participants received enough information, mostly from medical specialists (88.8%) and IBD nurses (79.4%). However, 51% wanted to be more involved in their healthcare. CONCLUSIONS: These data show discordance between expectations of patients and national standards with current levels of service provision, which fail to deliver equitable and comprehensive IBD care.

Vedolizumab in combined immune checkpoint therapy-induced infliximab-refractory colitis in a patient with metastatic melanoma: A case report.

BACKGROUND: Dual checkpoint inhibition improves response rates in treatment naïve patients with metastatic melanoma compared to monotherapy. However, it confers a higher rate of toxicity, including immune-related colitis. Steroids may not resolve symptoms in all cases. The use of vedolizumab, a humanized monoclonal antibody against α4ß7 integrin has proven effective in cases refractory to standard treatment. CASE SUMMARY: We report the case of a 27-year-old female with Stage IVd metastatic melanoma treated with ipilimumab and nivolumab. She developed severe colitis refractory to methylprednisolone, infliximab and mycophenolate mofetil but responded to vedolizumab. CONCLUSION: This case report supports vedolizumab use in severe immune related colitis refractory to standard immunosuppression.

Crohn's & Colitis Australia inflammatory bowel disease audit: measuring the quality of care in Australia.

BACKGROUND: Australia has among the highest prevalence of Crohn disease and ulcerative colitis in the world. Management of the chronic gastrointestinal disorders results in significant societal costs and the standard of care is inconsistent across Australia. AIM: To audit the quality of care received by patients admitted for inflammatory bowel disease (IBD) across Australia against national IBD standards. METHODS: A retrospective cross-sectional survey and clinical audit was undertaken assessing organisational resources, clinical processes and outcome measures. This study was conducted in Australian hospitals that care for inpatients with Crohn disease or ulcerative colitis. The main outcome measures were adherence to national IBD standards and comparison of quality of care between hospitals with and without multidisciplinary IBD services. RESULTS: A total of 71 hospitals completed the organisational survey. Only one hospital had a complete multidisciplinary IBD service and 17 had a partial IBD service (IBD nurse, helpline and clinical lead). A total of 1440 inpatient records was reviewed from 52 hospitals (mean age 37 years; 51% female, 53% Crohn disease), approximately 26% of IBD inpatient episodes over a 12-month period in Australia. These patients were chronically unwell with high rates of anaemia (30%) and frequent readmissions (40% within 2 years). In general, care was inconsistent, and documentation was poor. Hospitals with a partial IBD service performed better in many processes and outcome measures: for example, 22% reduction in admissions through emergency departments and greater adherence to standards for safety monitoring of biological (89% vs 59%) and immunosuppressive drugs (79% vs 55%) in those hospitals than those without. CONCLUSION: Patients admitted to hospital suffering from IBD are young, chronically unwell and are subject to substantial variations in clinical documentation and quality of care. Only one hospital met accepted standards for multidisciplinary care; hospitals with even a minimal IBD service provided improved care.

The microbiome of Crohn's disease aphthous ulcers.

BACKGROUND: Reduced intestinal microbial diversity and bacterial imbalance (dysbiosis) are seen in studies of Crohn's disease. As it is difficult to obtain biopsy samples before disease presentation, the earliest mucosal lesions in Crohn's disease, aphthous ulcers, present the best chance at assessing microbial communities at the onset of disease or a new flare. The aim of our study was to compare the microbial communities of aphthous ulcers and adjacent normal mucosa from patients with Crohn's disease with normal mucosa from controls. RESULTS: We did not observe bacterial imbalance or reduced alpha diversity in Crohn's disease aphthous ulcers and adjacent mucosa, relative to control biopsies. Bacteroides were common to all Crohn's disease and control samples, and there were no bacterial taxa unique to aphthous ulcers. The relative abundance of Faecalibacterium was not reduced in aphthous ulcers relative to control mucosa, and was not more likely to be detected in control samples. CONCLUSIONS: In contrast to well-documented changes seen in late-stage Crohn's disease, microbial communities of aphthous ulcers do not display evidence of bacterial imbalance or reduced diversity. Our data suggest that dysbiosis occurs during active disease, and improves when patients are in remission.

Prevalence of Yersinia Species in the Ileum of Crohn's Disease Patients and Controls.

Yersinia are common contaminants of food products, but their prevalence in the human gut is poorly documented. Yersinia have been implicated in Crohn's Disease (CD, an inflammatory bowel disease) however their role in CD is controversial. We performed highly sensitive PCR assays of specific sequences for the gyrB gene of Y. aldovae, Y. bercovieri, Y. enterocolitica, Y. intermedia, Y. mollaretii and the inv gene of Y. pseudotuberculosis. We analyzed a total of 470 ileal samples taken from 338 participants (262 CD patients and 76 controls) belonging to three independent cohorts. All patients and controls were phenotyped and genotyped for the main CD susceptibility variants: NOD2, ATG16L1, and IRGM. Yersinia were found in 7.7% of ileal samples (respectively 7.9 and 7.6% in controls and CD patients) corresponding to 10% of participants (respectively 11.8 and 9.5% in controls and CD patients). Y. enterocolitica, Y. pseudotuberculosis and Y. intermedia were the most frequently identified species. The bacteria were more frequent in resected specimens, lymph nodes and Peyer's patches. Yersinia were no more likely to be detected in CD tissues than tissues from inflammatory and non-inflammatory controls. CD patients treated with immunosuppressants were less likely to be Yersinia carriers. In conclusion, this work shows that Yersinia species are frequently found at low levels in the human ileum in health and disease. The role of Yersinia species in this ecosystem should now be explored.

The microbiome of translocated bacterial populations in patients with and without inflammatory bowel disease.

BACKGROUND: Using culture-based methods, bacterial translocation from the gut to draining mesenteric lymph nodes is seen in 5% of normal controls and up to 33% of patients with inflammatory bowel diseases (IBD). Many bacteria cannot be cultured, so these methods are unable to capture the full spectrum of bacteria present. AIMS: To detect viable bacteria in lymph nodes of patients with IBD and non-IBD controls using bacterial RNA as a surrogate for viability and to compare them with the same patient's gut microbiome. METHODS: Bacterial RNA was extracted from lymph nodes and mucosa of 20 patients who had undergone intestinal resection (10 IBD, 10 non-IBD). A previous study had detected bacterial DNA in these patients' lymph nodes; 16S rRNA gene high-throughput sequencing was performed. RESULTS: Bacterial RNA was detected in the lymph nodes of five patients with IBD and three controls (volvulus, diverticulitis and bowel obstruction). Lymph nodes had higher alpha (within sample) diversity compared to mucosal samples (Shannon diversity index 2.41 vs 1.81, one-way ANOVA P = 0.035). Beta diversity (inter-sample variation: lymph node vs intestine) was similar within individuals and did not differ between groups. Common gene polymorphisms linked with IBD (NOD2, ATG16L1, IRGM and IL23R) were not associated with bacterial translocation. CONCLUSIONS: Metabolically active bacteria mirroring the individual's gut microbiome were commonly found in the lymph nodes of patients with IBD undergoing resection. An increase in lymph node alpha diversity is likely due to the larger drainage area. The presence of viable bacteria in non-IBD controls is also not unexpected given the underlying pathology in these patients.

Inflammatory bowel disease-related fatigue is correlated with depression and gender.

OBJECTIVES: Fatigue is a common and disabling problem in inflammatory bowel disease. We sought to explore the possible determinants of inflammatory bowel disease-associated fatigue including demographic, psychological and disease variables. METHODS: Surveys were distributed to 100 patients undergoing infliximab infusion for inflammatory bowel disease in an infusion lounge, assessing attachment style (Experiences in Close Relationships Revised scale), fatigue (Functional Assessment of Chronic Illness Therapy Fatigue - Fatigue Subscore), and depression and anxiety (Hospital Anxiety and Depression Scale). Disease severity was assessed via file review through an independent gastroenterologist rating (Harvey-Bradshaw Index). RESULTS: There were 67 responses. Depression, as measured by the Hospital Anxiety and Depression Scale, was found to be highly correlated with fatigue (Functional Assessment of Chronic Illness Therapy Fatigue - Fatigue Subscore). Anxiety, insecure attachment, disease severity and female gender were moderately correlated with fatigue. In a hierarchical regression model, depression and female gender emerged as significant predictors of variance in fatigue scores. CONCLUSIONS: Depression was the strongest predictor of variance in fatigue scores. Gender as a cause of fatigue in inflammatory bowel disease requires further exploration. Attachment style, however, may still help clinicians to conceptualise help-seeking behaviour and clinician-patient relationships in medically unexplained symptoms.

Entyvio lengthen dose-interval study: lengthening vedolizumab dose interval and the risk of clinical relapse in inflammatory bowel disease.

BACKGROUND: Vedolizumab (VDZ), an α4ß7 anti-integrin antibody, is efficacious in the induction and maintenance of remission in ulcerative colitis (UC) and Crohn's disease (CD). In the GEMINI long-term safety study, enrolled patients received 4-weekly VDZ. Upon completion, patients were switched to 8-weekly VDZ in Australia. The clinical success rate of treatment de-escalation for patients in remission on VDZ has not been described previously. AIM: To determine the proportion of patients who relapsed after switching from 4 to 8-weekly VDZ, the mean time to relapse, and the recapture rate when switching back to 8-weekly dosing. MATERIALS AND METHODS: This was a retrospective, observational, multicenter study of patients previously recruited into GEMINI long-term safety in Australia. Data on the demographics and biochemical findings were collected. RESULTS: There were 34 patients [23 men, mean age 49.1 (±13.1) years] and their mean disease duration was 17.6 (±8.5) years. The mean 4-weekly VDZ infusion duration was 286.5 (±48.8) weeks. A total of five (15%) patients relapsed on dose-interval increase (4/17 UC, 1/17 CD) at a median duration from dose interval lengthening to flare of 14 weeks (interquartile range=6-25). Eighty percent (4/5) of patients re-entered remission following dose-interval decrease back to 4-weekly. No clinical predictors of relapse could be determined because of the small cohort size. CONCLUSION: The risk of patients relapsing when switching from 4 to 8-weekly VDZ ∼15% and is similar between CD and UC. Dose-interval decrease recaptures 80% of patients who relapsed. Therapeutic drug monitoring of VDZ may be of clinical relevance.

The role of inflammation in temporal shifts in the inflammatory bowel disease mucosal microbiome.

Studies of the human intestinal microbiome in patients with inflammatory bowel disease (IBD) consistently show that there are differences (an abnormal or unbalanced microbiome, "dysbiosis") when compared to healthy subjects. We sought to describe changes in the microbiome in individual patients over time, and determine the clinical factors that are associated with significant alteration. Forty-two mucosal biopsies were collected from 20 patients that were spaced an average of 2.4 years apart. These were analysed using bacterial 16S rRNA gene high-throughput sequencing methods. Presence of active inflammation was determined endoscopically and histologically. Inferred metagenomics analysis was conducted using the PICRUSt package. We found that the differences in the microbiome over time in individual patients were greatest in the presence of ongoing intestinal inflammation, as determined by the Yue and Clayton theta distance between sample pairs (adjusted p = 0.00031). Samples from patients with previous abdominal surgery had lower alpha (within sample) diversity compared with those with no prior operations (mean Shannon index 2.083, 2.510 respectively, p = 0.017). There were no changes in the inferred bacterial metagenomic profile. The microbiome in IBD undergoes considerable fluctuation over time. These changes are greatest when there is histologically confirmed inflammation at both time-points.

Genital Granulomatosis in Male and Female Patients With Crohn's Disease: Clinical Presentation and Treatment Outcomes.

BACKGROUND: Genital granulomatosis [GG] is a metastatic form of Crohn's disease [CD], characterised by granulomatous inflammation of the genital skin without contact with the gastrointestinal tract. Little is known about GG, as most publications are case reports or small series, and only sporadic in male cases. METHODS AND AIMS: Cases of GG were retrospectively collected through the Collaborative Network For Exceptionally Rare case reports project of the European Crohn's and Colitis Organisation. RESULTS: A total of 43 patients [9 males, 34 females] were diagnosed as having GG, mostly as oedema and/or ulcers. Histological confirmation of granulomas was obtained in 70% of the cases. CD location was colonic or ileocolonic in 97% and perianal disease was documented in 57%. There was no significant difference between males and females in CD phenotype or genital lesions. GG was the first manifestation of inflammatory bowel disease [IBD] in one-third of the patients; these patients were younger at the time of GG occurrence and they all were non-smokers. GG occurred in the absence of gastrointestinal disease activity in 30% of the cases. Ten out of 11 patients [91%] responded to systemic corticosteroid treatment, 5/9 patients responded to immunomodulators, and 9/11 patients responded to anti-tumour necrosis factor alpha [TNF-α] agents. CONCLUSIONS: GG is a rare extraintestinal manifestation of CD. It mainly occurs among women, in the setting of colonic involvement of CD, and perianal disease is often associated. Most cases are successfully managed with systemic corticosteroids or anti-TNF agents.

Within-host evolution versus immigration as a determinant of Escherichia coli diversity in the human gastrointestinal tract.

When a human host harbors two or more strains of Escherichia coli, the second strain is more likely to be a member of the same phylogroup rather than a different phylogroup. This outcome may be the consequence of a within host evolution event or an independent immigration/establishment event. To determine the relative importance of these two events in determining E. coli diversity in a host, a collection of multiple E. coli isolates recovered from each of 67 patients undergoing colonoscopies was used. Whole genome sequence data were available for one example of every REP-fingerprint type identified in a patient. Sequence type (ST) and single-nucleotide polymorphism (SNP) analyses revealed that 83% of strains observed in the host population were a consequence of immigration/establishment events. Restricting the analysis to hosts harboring two or more strains belonging to the same phylogroup revealed that in about half of these cases, the presence of a second strain belonging to the same phylogroup was the consequence of an independent immigration/establishment event. Thus, the results of this study show that despite hosts being exposed to a diversity of E. coli via their food, factors related to the host also determine what E. coli strains succeed in establishing.

Paradoxical psoriasiform reactions of anti-tumour necrosis factor therapy in inflammatory bowel disease patients.

Anti-tumour necrosis factor (TNF) agents have demonstrated efficacy in inflammatory bowel disease (IBD). Cutaneous reactions such as new onset psoriasis or psoriasiform-like reactions are among the most common adverse reactions. We retrospectively identified cases of anti-TNF-induced psoriasis or psoriasiform manifestations in IBD patients at a tertiary centre in Australia. A total of 10 (six females) of 270 (3.7%) IBD patients treated with anti-TNF therapy developed drug-induced psoriatic or psoriasiform-like reactions: five patients were treated with infliximab and five with adalimumab; nine had Crohn disease. The time from initiation of anti-TNF agent to onset of rash was 7.5 months on average. The most frequent distributions were the scalp (7/10) and extremities (6/10). Three patients discontinued anti-TNF treatment with resolution of the rash. Topical treatment of the lesions allowed continued use of biological agent in the majority. Paradoxical psoriatic lesions are recognised adverse events associated with anti-TNF therapy, but discontinuation of therapy due to dermatological complications is required only rarely, even in patients with psoriasiform lesions.

Fine-Scale Structure Analysis Shows Epidemic Patterns of Clonal Complex 95, a Cosmopolitan Escherichia coli Lineage Responsible for Extraintestinal Infection.

The Escherichia coli lineage known as clonal complex 95 (CC95) is a cosmopolitan human-associated lineage responsible for a significant fraction of extraintestinal infections of humans. Whole-genome sequence data of 200 CC95 strains from various origins enabled determination of the CC95 pangenome. The pangenome analysis revealed that strains of the complex could be assigned to one of five subgroups that vary in their serotype, extraintestinal virulence, virulence gene content, and antibiotic resistance gene profile. A total of 511 CC95 strains isolated from humans living in France, Australia, and the United States were screened for their subgroup membership using a PCR-based method. The CC95 subgroups are nonrandomly distributed with respect to their geographic origin. The relative frequency of the subgroups was shown to change through time, although the nature of the changes varies with continent. Strains of the subgroups are also nonrandomly distributed with respect to source of isolation (blood, urine, or feces) and host sex. Collectively, the evidence indicates that although strains belonging to CC95 may be cosmopolitan, human movement patterns have been insufficient to homogenize the distribution of the CC95 subgroups. Rather, the manner in which CC95 strains evolve appears to vary both spatially and temporally. Although CC95 strains appeared globally as pandemic, fine-scale structure analysis shows epidemic patterns of the CC95 subgroups. Furthermore, the observation that the relative frequency of CC95 subgroups at a single locality has changed over time indicates that the relative fitness of the subgroups has changed. IMPORTANCEEscherichia coli clonal complex 95 represents a cosmopolitan, genetically diverse lineage, and the extensive substructure observed in this lineage is epidemiologically and clinically relevant. The frequency with which CC95 strains are responsible for extraintestinal infection appears to have been stable over the past 15 years. However, the different subgroups identified within this lineage have an epidemic structure depending on the host, sample, continent, and time. Thus, the evolution and spread of strains belonging to CC95 are very different from those of another cosmopolitan human-associated clonal complex, CC131, which has increased significantly in frequency as a cause of extraintestinal infection over the past 15 years due to the evolution and spread of two very closely related, nearly monomorphic lineages.

Analysis of the human monocyte-derived macrophage transcriptome and response to lipopolysaccharide provides new insights into genetic aetiology of inflammatory bowel disease.

The FANTOM5 consortium utilised cap analysis of gene expression (CAGE) to provide an unprecedented insight into transcriptional regulation in human cells and tissues. In the current study, we have used CAGE-based transcriptional profiling on an extended dense time course of the response of human monocyte-derived macrophages grown in macrophage colony-stimulating factor (CSF1) to bacterial lipopolysaccharide (LPS). We propose that this system provides a model for the differentiation and adaptation of monocytes entering the intestinal lamina propria. The response to LPS is shown to be a cascade of successive waves of transient gene expression extending over at least 48 hours, with hundreds of positive and negative regulatory loops. Promoter analysis using motif activity response analysis (MARA) identified some of the transcription factors likely to be responsible for the temporal profile of transcriptional activation. Each LPS-inducible locus was associated with multiple inducible enhancers, and in each case, transient eRNA transcription at multiple sites detected by CAGE preceded the appearance of promoter-associated transcripts. LPS-inducible long non-coding RNAs were commonly associated with clusters of inducible enhancers. We used these data to re-examine the hundreds of loci associated with susceptibility to inflammatory bowel disease (IBD) in genome-wide association studies. Loci associated with IBD were strongly and specifically (relative to rheumatoid arthritis and unrelated traits) enriched for promoters that were regulated in monocyte differentiation or activation. Amongst previously-identified IBD susceptibility loci, the vast majority contained at least one promoter that was regulated in CSF1-dependent monocyte-macrophage transitions and/or in response to LPS. On this basis, we concluded that IBD loci are strongly-enriched for monocyte-specific genes, and identified at least 134 additional candidate genes associated with IBD susceptibility from reanalysis of published GWA studies. We propose that dysregulation of monocyte adaptation to the environment of the gastrointestinal mucosa is the key process leading to inflammatory bowel disease.

Comparative genomics of Crohn's disease-associated adherent-invasive Escherichia coli.

OBJECTIVE: Adherent-invasive Escherichia coli (AIEC) are a leading candidate bacterial trigger for Crohn's disease (CD). The AIEC pathovar is defined by in vitro cell-line assays examining specific bacteria/cell interactions. No molecular marker exists for their identification. Our aim was to identify a molecular property common to the AIEC phenotype. DESIGN: 41 B2 phylogroup E. coli strains were isolated from 36 Australian subjects: 19 patients with IBD and 17 without. Adherence/invasion assays were conducted using the I-407 epithelial cell line and survival/replication assays using the THP-1 macrophage cell line. Cytokine secretion tumour necrosis factor ((TNF)-α, interleukin (IL) 6, IL-8 and IL-10) was measured using ELISA. The genomes were assembled and annotated, and cluster analysis performed using CD-HIT. The resulting matrices were analysed to identify genes unique/more frequent in AIEC strains compared with non-AIEC strains. Base composition differences and clustered regularly interspaced palindromic repeat (CRISPR) analyses were conducted. RESULTS: Of all B2 phylogroup strains assessed, 79% could survive and replicate in macrophages. Among them, 11/41 strains (5 CD, 2 UCs, 5 non-IBD) also adhere to and invade epithelial cells, a phenotype assigning them to the AIEC pathovar. The AIEC strains were phylogenetically heterogeneous. We did not identify a gene (or nucleic acid base composition differences) common to all, or the majority of, AIEC. Cytokine secretion and CRISPRs were not associated with the AIEC phenotype. CONCLUSIONS: Comparative genomic analysis of AIEC and non-AIEC strains did not identify a molecular property exclusive to the AIEC phenotype. We recommend a broader approach to the identification of the bacteria-host interactions that are important in the pathogenesis of Crohn's disease.

Gut feelings 1. Mind, mood and gut in irritable bowel syndrome: approaches to psychiatric care.

OBJECTIVE: Psychiatrists are likely to encounter patients with irritable bowel syndrome (IBS). We aim to provide a clinically-focused summary of psychiatric comorbidities and management. CONCLUSIONS: IBS affects up to 15% of the population. Antidepressants and brief psychotherapy can reduce symptom severity and improve coping. These treatments are effective for patients without comorbid mental illness, as well as those with increased somatisation, health-care seeking and sexual abuse histories.