Author Correction: Gut microbiome structure and metabolic activity in inflammatory bowel disease

In the Supplementary Tables 2, 4 and 6 originally published with this Article, the authors mistakenly included sample identifiers in the form of UMCGs rather than UMCG IBDs in the validation cohort; this has now been amended.

Gut microbiome structure and metabolic activity in inflammatory bowel disease

The inflammatory bowel diseases (IBDs), which include Crohn's disease (CD) and ulcerative colitis (UC), are multifactorial chronic conditions of the gastrointestinal tract. While IBD has been associated with dramatic changes in the gut microbiota, changes in the gut metabolome-the molecular interface between host and microbiota-are less well understood. To address this gap, we performed untargeted metabolomic and shotgun metagenomic profiling of cross-sectional stool samples from discovery (n = 155) and validation (n = 65) cohorts of CD, UC and non-IBD control patients. Metabolomic and metagenomic profiles were broadly correlated with faecal calprotectin levels (a measure of gut inflammation). Across >8,000 measured metabolite features, we identified chemicals and chemical classes that were differentially abundant in IBD, including enrichments for sphingolipids and bile acids, and depletions for triacylglycerols and tetrapyrroles. While > 50% of differentially abundant metabolite features were uncharacterized, many could be assigned putative roles through metabolomic 'guilt by association' (covariation with known metabolites). Differentially abundant species and functions from the metagenomic profiles reflected adaptation to oxidative stress in the IBD gut, and were individually consistent with previous findings. Integrating these data, however, we identified 122 robust associations between differentially abundant species and well-characterized differentially abundant metabolites, indicating possible mechanistic relationships that are perturbed in IBD. Finally, we found that metabolome- and metagenome-based classifiers of IBD status were highly accurate and, like the vast majority of individual trends, generalized well to the independent validation cohort. Our findings thus provide an improved understanding of perturbations of the microbiome-metabolome interface in IBD, including identification of many potential diagnostic and therapeutic targets.

Gut Microbiome Function Predicts Response to Anti-integrin Biologic Therapy in Inflammatory Bowel Diseases

The gut microbiome plays a central role in inflammatory bowel diseases (IBDs) pathogenesis and propagation. To determine whether the gut microbiome may predict responses to IBD therapy, we conducted a prospective study with Crohn's disease (CD) or ulcerative colitis (UC) patients initiating anti-integrin therapy (vedolizumab). Disease activity and stool metagenomes at baseline, and weeks 14, 30, and 54 after therapy initiation were assessed. Community α-diversity was significantly higher, and Roseburia inulinivorans and a Burkholderiales species were more abundant at baseline among CD patients achieving week 14 remission. Several significant associations were identified with microbial function; 13 pathways including branched chain amino acid synthesis were significantly enriched in baseline samples from CD patients achieving remission. A neural network algorithm, vedoNet, incorporating microbiome and clinical data, provided highest classifying power for clinical remission. We hypothesize that the trajectory of early microbiome changes may be a marker of response to IBD treatment.

High C-Reactive Protein Is Associated with Poor Sleep Quality Independent of Nocturnal Symptoms in Patients with Inflammatory Bowel Disease

BACKGROUND

Sleep disruption is common in inflammatory bowel diseases (IBD). However, studies demonstrating a similar prevalence in irritable bowel syndrome suggest that nighttime disruption due to diarrhea and abdominal pain may be key drivers of poor sleep quality. Whether inflammation is associated with poor sleep independently has not been examined previously.

METHODS

This single-center study included subjects with IBD recruited to an ongoing prospective registry who completed a questionnaire assessing sleep quality and mood. Inflammatory marker levels [C-reactive protein (CRP), erythrocyte sedimentation rate] and clinical disease activity including nighttime disruption on the day of enrollment were obtained from the medical record. Logistic regression models were used to identify predictors of sleep quality.

RESULTS

The study included 131 subjects (72 women) with a median age of IBD diagnosis of 25 years. Twenty-three subjects (19 %) had a high C-reactive protein level (≥8 mg/dL). Poor sleep was more common in those with high CRP levels than with normal values (70 vs. 39 %, p = 0.009). This association remained significant on multivariate analysis [Odds ratio (OR) 4.12, 95 % confidence interval (CI) 1.38-12.29]. Adjusting for the presence of nighttime disruption did not significant alter this association (OR 3.16, 95 % CI 1.01-9.90). High CRP correlated with poor sleep even in patients not experiencing nocturnal symptoms (n = 101, OR 4.89, 95 % CI 1.24-19.36).

CONCLUSION

High CRP is associated with poor sleep quality in IBD independent of the presence of nighttime disruptions, suggesting that a relationship exists between circulating inflammatory markers and sleep.

Attraction of immature stages of the American dog tick (Dermacentor variabilis) to 2,6-dichlorophenol

To determine whether 2,6-dichlorophenol is solely a sex pheromone, the response to it by the various stages of the American dog tick, Dermacentor variabilis, were compared. In contrast to adults, 2,6-dichlorophenol was attractive to unfed nymphs and to unfed larvae. Use of this chemical also prompted the expression of a novel type of 'feeding' posture behavior in adults. The overlap in attraction to other substituted phenols plus the lack of functional value of this response for larvae and nymphs rules out the possibility that 2,6-dichlorophenol is a general attractant. However, 2,6-dichlorophenol likely plays a dual role as an attachment stimulant in the adult tick.

Squalene: a naturally abundant mammalian skin secretion and long distance tick-attractant (Acari: Ixodidae)

Squalene is a naturally occurring lipid on mammalian skin and is an attractant to the lone star tick, Amblyomma americanum (L.). In this study, we compared squalene to the standard tick-attractants, benzaldehyde, isobutyric acid, methyl salicylate, nonanoic acid, and o-nitrophenol identified as active ingredients of tick aggregation-attachment pheromones and determined its effectiveness in field and laboratory settings at varying distances. Squalene was detected from 1/4 m greater than the standard tick attractants, attracted a greater percentage of ticks (75 compared with 0-43%) and featured a rapid response time (< 30 min). Thus, squalene contributes more to the tick's ability to locate hosts at greater distances than aggregation-attachment pheromones. These results have important implications for improving tick monitoring and control programs by adding squalene as a supplement to existing attractant baits.