The NOD2-Smoking Interaction in Crohn's Disease is likely Specific to the 1007fs Mutation and may be Explained by Age at Diagnosis: A Meta-Analysis and Case-Only Study

NOD2 and Crohn's Disease Clinical Practice: From Epidemiology to Diagnosis and Therapy, Rewired

Crohn's disease (CD) is a chronic inflammatory bowel disease with a multifactorial pathogenesis involving environmental and genetic factors. Since the late 20th century, the discovery of the first susceptibility gene (NOD2, previously referred to as CARD15) for CD has paved the way for further investigations into the correlations between clinical features and genetics, and its potential impact on clinical practice has fueled the research in the last 2 decades. Recent therapeutic advancements involving novel biologic drugs and small molecules have shifted inflammatory bowel disease management from a disease-centered to a patient-centric approach. To date, the role of NOD2 has not been fully understood yet. Recent data suggest that its clinical impact may be greater than currently recognized. This review overviews the most common NOD2 variants' role in real-life clinical practice. These genetic variants increase the risk of developing the disease and can aid in tailoring diagnosis and treatment. They are associated with the stricturing phenotype and ileal involvement and increase the risk of steroid refractoriness. In the meantime, limited and inconclusive evidence exists regarding their predictive role in response to azathioprine, biologic drugs, and small molecules. Eventually, their role in increasing the risk for surgery is evident, especially in those with the L1007fs variant. If further trials will support the initial evidence reported so far, NOD2 genetic variants will emerge as possible candidates for developing precision medicine in CD.

Forecasting the Incidence and Prevalence of Inflammatory Bowel Disease: A Canadian Nationwide Analysis

INTRODUCTION

Canada has a high burden of inflammatory bowel disease (IBD). Historical trends of IBD incidence and prevalence were analyzed to forecast the Canadian burden over the next decade.

METHODS

Population-based surveillance cohorts in 8 provinces derived from health administrative data assessed the national incidence (2007-2014) and prevalence (2002-2014) of IBD. Autoregressive integrated moving average models were used to forecast incidence and prevalence, stratified by age, with 95% prediction intervals (PI), to 2035. The average annual percentage change (AAPC) with 95% confidence interval (CI) was calculated for the forecasted incidence and prevalence.

RESULTS

The national incidence of IBD is estimated to be 29.9 per 100,000 (95% PI 28.3-31.5) in 2023. With a stable AAPC of 0.36% (95% CI -0.05 to 0.72), the incidence of IBD is forecasted to be 31.2 per 100,000 (95% PI 28.1-34.3) in 2035. The incidence in pediatric patients (younger than 18 years) is increasing (AAPC 1.27%; 95% CI 0.82-1.67), but it is stable in adults (AAPC 0.26%; 95% CI -0.42 to 0.82). The prevalence of IBD in Canada was 843 per 100,000 (95% PI 716-735) in 2023 and is expected to steadily climb (AAPC 2.43%; 95% CI 2.32-2.54) to 1,098 per 100,000 (95% PI 1,068-1,127) by 2035. The highest prevalence is in seniors with IBD (1,174 per 100,000 in 2023; AAPC 2.78%; 95% CI 2.75-2.81).

DISCUSSION

Over the next decade, the Canadian health care systems will contend with the juxtaposition of rising incidence of pediatric IBD and a rising prevalence of overall IBD driven by the aging population.

Autophagy activation alleviates the LPS-induced inflammatory response in endometrial epithelial cells in dairy cows

PROBLEM

Endometritis is a common disease that affects dairy cow reproduction. Autophagy plays a vital role in cellular homeostasis and modulates inflammation by regulating interactions with innate immune signaling pathways. However, little is known about the regulatory relationship between autophagy and inflammation in bovine endometrial epithelial cells (BEECs). Thus, we aimed to determine the role of autophagy in the inflammatory response in BEECs.

METHODS OF STUDY

In the present study, the expression levels of proinflammatory cytokines were measured by quantitative real-time polymerase chain reaction. Changes in the nuclear factor-κB (NF-κB) pathway and autophagy were determined using immunoblotting and immunocytochemistry. The induction of autophagosome formation was visualized by transmission electron microscopy.

RESULTS

Our results demonstrated that autophagy activation was inhibited in LPS-treated BEECs, while activation of the NF-κB pathway and the mRNA expression of IL-6, IL-8, and TNF-α were increased. Furthermore, blocking autophagy with the inhibitor chloroquine increased NF-κB signaling pathway activation and proinflammatory factor expression in LPS-treated BEECs. Conversely, activation of autophagy with the agonist rapamycin inhibited the NF-κB signaling pathway and downregulated proinflammatory factors.

CONCLUSIONS

These data indicated that LPS-induced inflammation was related to the inhibition of autophagy in BEECs. Thus, the activation of autophagy may represent a novel therapeutic strategy for eliminating inflammation in BEECs.

Epidemiology of Pediatric Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), including subtypes Crohn disease and ulcerative colitis is a chronic inflammatory disorder most often diagnosed in young adulthood. The incidence and prevalence of pediatric-onset IBD is increasing globally. IBD is likely caused by an interplay of multiple environmental factors resulting in a dysregulated mucosal response to the commensal intestinal microbiota in genetically predisposed individuals. This article provides an overview of pediatric IBD epidemiology and environmental risk factors associated with its development, such as the Hygiene Hypothesis, air pollution, greenspace and blue space, neonatal factors, antibiotics, and diet.

How autophagy, a potential therapeutic target, regulates intestinal inflammation

Inflammatory bowel disease (IBD) is a group of disorders that cause chronic inflammation in the intestines, with the primary types including ulcerative colitis and Crohn's disease. The link between autophagy, a catabolic mechanism in which cells clear protein aggregates and damaged organelles, and intestinal health has been widely studied. Experimental animal studies and human clinical studies have revealed that autophagy is pivotal for intestinal homeostasis maintenance, gut ecology regulation and other aspects. However, few articles have summarized and discussed the pathways by which autophagy improves or exacerbates IBD. Here, we review how autophagy alleviates IBD through the specific genes (e.g., ATG16L1, IRGM, NOD2 and LRRK2), crosstalk of multiple phenotypes with autophagy (e.g., Interaction of autophagy with endoplasmic reticulum stress, intestinal antimicrobial defense and apoptosis) and autophagy-associated signaling pathways. Moreover, we briefly discuss the role of autophagy in colorectal cancer and current status of autophagy-based drug research for IBD. It should be emphasized that autophagy has cell-specific and environment-specific effects on the gut. One of the problems of IBD research is to understand how autophagy plays a role in intestinal tract under specific environmental factors. A better understanding of the mechanism of autophagy in the occurrence and progression of IBD will provide references for the development of therapeutic drugs and disease management for IBD in the future.

CXCR3 Inhibition Blocks the NF-κB Signaling Pathway by Elevating Autophagy to Ameliorate Lipopolysaccharide-Induced Intestinal Dysfunction in Mice

Autophagy is a cellular catabolic process in the evolutionarily conservative turnover of intracellular substances in eukaryotes, which is involved in both immune homeostasis and injury repairment. CXCR3 is an interferon-induced chemokine receptor that participates in immune regulation and inflammatory responses. However, CXCR3 regulating intestine injury via autophagy along with the precise underlying mechanism have yet to be elucidated. In the current study, we employed an LPS-induced inflammatory mouse model and confirmed that CXCR3 knockout significantly attenuates intestinal mucosal structural damage and increases tight junction protein expression. CXCR3 knockout alleviated the LPS-induced increase in the expression of inflammatory factors including TNF-α, IL-6, p-65, and JNK-1 and enhanced autophagy by elevating LC3II, ATG12, and PINK1/Parkin expression. Mechanistically, the function of CXCR3 regarding autophagy and immunity was investigated in IPEC-J2 cells. CXCR3 inhibition by AMG487 enhanced autophagy and reduced the inflammatory response, as well as blocked the NF-κB signaling pathway and elevated the expression of the tight junction protein marker Claudin-1. Correspondingly, these effects were abolished by autophagy inhibition with the selective blocker, 3-MA. Moreover, the immunofluorescence assay results further demonstrated that CXCR3 inhibition-mediated autophagy blocked p65 nuclear translocation, and the majority of Claudin-1 was located at the tight junctions. In conclusion, CXCR3 inhibition reversed LPS-induced intestinal barrier damage and alleviated the NF-κB signaling pathway via enhancing autophagy. These data provided a theoretical basis for elucidating the immunoregulatory mechanism by targeting CXCR3 to prevent intestinal dysfunction.

Oral supplementation with selected Lactobacillus acidophilus triggers IL-17-dependent innate defense response, activation of innate lymphoid cells type 3 and improves colitis

Live biotherapeutic products constitute an emerging therapeutic approach to prevent or treat inflammatory bowel diseases. Lactobacillus acidophilus is a constituent of the human microbiota with probiotic potential, that is illustrated by improvement of intestinal inflammation and antimicrobial activity against several pathogens. In this study, we evaluated the immunomodulatory properties of the L. acidophilus strain BIO5768 at steady state and upon acute inflammation. Supplementation of naïve mice with BIO5768 heightened the transcript level of some IL-17 target genes encoding for protein with microbicidal activity independently of NOD2 signaling. Of these, the BIO5768-induced expression of Angiogenin-4 was blunted in monocolonized mice that are deficient for the receptor of IL-17 (but not for NOD2). Interestingly, priming of bone marrow derived dendritic cells by BIO5768 enhanced their ability to support the secretion of IL-17 by CD4⁺ T cells. Equally of importance, the production of IL-22 by type 3 innate lymphoid cells is concomitantly heightened in response to BIO5768. When administered alone or in combination with Bifidobacterium animalis spp. lactis BIO5764 and Limosilactobacillus reuteri, BIO5768 was able to alleviate at least partially intestinal inflammation induced by Citrobacter rodentium infection. Furthermore, BIO5768 was also able to improve colitis induced by 2,4,6-trinitrobenzene sulfonic acid (TNBS). In conclusion, we identify a new potential probiotic strain for the management of inflammatory bowel diseases, and provide some insights into its IL-17-dependent and independent mode of action.

Twenty-first Century Trends in the Global Epidemiology of Pediatric-Onset Inflammatory Bowel Disease: Systematic Review

BACKGROUND & AIMS

The incidence of inflammatory bowel disease (IBD) is increasing internationally, particularly in nations with historically low rates. Previous reports of the epidemiology of pediatric-onset IBD identified a paucity of data. We systematically reviewed the global trends in incidence and prevalence of IBD diagnosed in individuals <21 years old over the first 2 decades of the 21st century.

METHODS

We systematically reviewed studies indexed in MEDLINE, EMBASE, Airiti Library, and SciELO from January 2010 to February 2020 to identify population-based studies reporting the incidence and/or prevalence of IBD, Crohn's disease, ulcerative colitis, and/or IBD-unclassified. Data from studies published before 2000 were derived from a previously published systematic review. We described the geographic distribution and trends in children of all ages and limiting to very early onset (VEO) IBD.

RESULTS

A total of 131 studies from 48 countries were included. The incidence and prevalence of pediatric-onset IBD is highest in Northern Europe and North America and lowest in Southern Europe, Asia, and the Middle East. Among studies evaluating trends over time, most (31 of 37, 84%) studies reported significant increases in incidence and all (7 of 7) reported significant increases in prevalence. Data on the incidence and prevalence of VEO-IBD are limited to countries with historically high rates of IBD. Time trends in the incidence of VEO-IBD were visually heterogeneous.

CONCLUSIONS

Rates of pediatric-onset IBD continue to rise around the world and data are emerging from regions where it was not previously reported; however, there remains a paucity of data on VEO-IBD and on pediatric IBD from developing and recently developed countries.

Insight Into Polysaccharides From Panax ginseng C. A. Meyer in Improving Intestinal Inflammation: Modulating Intestinal Microbiota and Autophagy

Polysaccharides from Panax ginseng C. A. Meyer (P. ginseng) are the main active component of P. ginseng and exhibit significant intestinal anti-inflammatory activity. However, the therapeutic mechanism of the ginseng polysaccharide is unclear, and this hinders the application for medicine or functional food. In this study, a polysaccharide was isolated from P. ginseng (GP). The primary structure and morphology of the GP were studied by HPLC, FT-IR spectroscopy, and scanning electron microscopy (SEM). Further, its intestinal anti-inflammatory activity and its mechanism of function were evaluated in experimental systems using DSS-induced rats, fecal microbiota transplantation (FMT), and LPS-stimulated HT-29 cells. Results showed that GP modulated the structure of gut microbiota and restored mTOR-dependent autophagic dysfunction. Consequently, active autophagy suppressed inflammation through the inhibition of NF-κB, oxidative stress, and the release of cytokines. Therefore, our research provides a rationale for future investigations into the relationship between microbiota and autophagy and revealed the therapeutic potential of GP for inflammatory bowel disease.

NOD2 signalling in hidradenitis suppurativa

BACKGROUND

Hidradenitis suppurativa (HS) is associated with dysregulated immune responses including altered expression of cytokines, chemokines, and antimicrobial peptides and proteins (AMPs).

AIMS

To evaluate the expression of nucleotide-binding oligomerization domain-containing (NOD)2 and related factors in HS skin samples and keratinocyte cultures.

METHODS

We performed real-time PCR for NOD2, receptor-interacting serine/threonine-protein kinase (RIP)2, cyclic amine resistance locus (CARL), skin-derived antileukoproteinase (SKALP)/elafin, human β-defensin (hBD)2, LL37, psoriasin and RNAse7 in lesional and nonlesional skin of 19 patients with HS and in keratinocyte cultures [unstimulated, muramyl dipeptide (MDP)-stimulated or Pam2CSK4 (Pam2)-stimulated] from and nonlesional skin.

RESULTS

We observed significantly elevated mRNA expression for NOD2 (P < 0.01), hBD2 (P = 0.02), RNase7 (P < 0.001), psoriasin (P < 0.01) and SKALP/elafin (P = 0.02) in lesional compared with nonlesional skin. We found a significant correlation between NOD2 mRNA and hBD2 (r = 46; P = 0.04), psoriasin (r = 0.67; P < 0.01) and SKALP/elafin (r = 0.65; P < 0.01). In unstimulated, Pam2-stimulated and MDP-stimulated normal keratinocytes, NOD2, RIP2, CARL and SKALP/elafin expression significantly (P < 0.05) increased from 6 to 48 h, whereas in unstimulated, Pam2-stimulated and MDP-stimulated HS keratinocytes, RIP2, CARL and SKALP/elafin expression significantly (P < 0.05) declined from 6 to 48 h. mRNA expression of NOD2 (unstimulated, Pam2-stimulated, MDP-stimulated), CARL (unstimulated, Pam2-stimulated, MDP-stimulated) and SKALP/elafin (unstimulated, Pam2-stimulated) at 6 h was significantly increased in HS compared with normal keratinocytes.

CONCLUSION

We have shown for the first time that NOD2 signalling is activated in HS and might contribute to the pathogenesis via induction of AMPs and activation of other pathways such as nuclear factor κB signalling.

The Genetics of Postoperative Recurrence in Crohn Disease: A Systematic Review, Meta-analysis, and Framework for Future Work

Background

Recurrence following abdominal surgery in Crohn disease is over 50%. The impact of genetics on postoperative recurrence is not well defined.

Methods

A literature search was conducted where inclusion required an assessment, by genotype, of postoperative recurrence. The primary endpoint was odds of surgical recurrence.

Results

Twenty-eight studies identified a total of 6715 patients. Thirteen loci were identified as modifying the risk of recurrence. NOD2 was identified as a risk factor for recurrence by multiple works (cumulative odds ratio: 1.64, P = 0.003).

Conclusions

A NOD2 risk allele is associated with recurrence following surgery in Crohn disease. Progress in this area will require standardized reporting in future works.

Serum Newborn Screening Blood Metabolites Are not Associated With Childhood-onset Inflammatory Bowel Disease: A Population-based Matched Case-control Study

BACKGROUND

Originally used for screening of inborn errors of metabolism, routine metabolite profiles of newborns have also been associated with prematurity and some childhood diseases. We sought to determine whether metabolites measured during routine newborn screening could identify infants who develop inflammatory bowel disease (IBD) in childhood.

METHODS

We conducted a population-based matched case-control study using health administrative data from Ontario, Canada. Children born 2006 to 2015 with IBD were identified using a validated algorithm and matched to 5 controls based on birth date, sex, rural/urban household, and mean neighborhood income quintile at birth. Cases and controls were linked deterministically to metabolic profiles from Newborn Screening Ontario. We fit a lasso penalized logistic regression model and used 10-fold cross-validation to obtain internally valid performance measures. Models included metabolites, amino acids, and endocrine markers. Models also included ratios of metabolites, gestational age, birth weight, mode of delivery, age at serum collection, maternal age at delivery, maternal history of IBD, and parity.

RESULTS

Three hundred eight cases of IBD, diagnosed at 5.5 ± 2.8 years, were matched to 1540 controls. No individual metabolites were associated with IBD. The c-statistic was 0.50 for the training data. After 10-fold cross-validation the C statistic was 0.50, indicating no significant association between metabolites and IBD diagnosis.

CONCLUSIONS

Newborn screening serum metabolites could not identify children who will develop IBD in this population-based cohort. Future studies with an expanded panel of metabolites may provide improved prediction of IBD.

Opportunities and challenges in using real-world data for health care

Real-world data (RWD) continue to emerge as a new source of clinical evidence. Although the best-known use case of RWD has been in drug regulation, RWD are being generated and used by many other parties, including biopharmaceutical companies, payors, clinical researchers, providers, and patients. In this Review, we describe 21 potential uses for RWD across the spectrum of health care. We also discuss important challenges and limitations relevant to the translation of these data into evidence.

Global smoking trends in inflammatory bowel disease: A systematic review of inception cohorts

Background and aims

The effect of smoking on the risk of developing inflammatory bowel diseases (IBD) may be heterogeneous across ethnicity and geography. Although trends in smoking for the general population are well described, it is unknown whether these can be extrapolated to the IBD cohort. Smoking prevalence trends specific to the global IBD cohort over time have not been previously reported. This is a systematic review of smoking prevalence specific to the IBD cohort across geography.

Methods

A systematic literature search was conducted on Medline and Embase from January 1^st 1946 to April 5^th 2018 to identify population-based studies assessing the prevalence of smoking at diagnosis in inception cohorts of Crohn’s disease(CD) or ulcerative colitis(UC). Studies that did not report smoking data from time of diagnosis or the year of IBD diagnosis were excluded. Prevalence of smoking in IBD was stratified by geography and across time.

Results

We identified 56 studies that were eligible for inclusion. Smoking prevalence data at diagnosis of CD and UC was collected from twenty and twenty-five countries respectively. Never-smokers in the newly diagnosed CD population in the West has increased over the last two decades, especially in the United Kingdom and Sweden; +26.6% and +11.2% respectively. Never-smokers at CD diagnosis in newly industrialised nations have decreased over the 1990s and 2000s; China (-19.36%). Never-smokers at UC diagnosis also decreased in China; -15.4%. The former-smoker population at UC diagnosis in China is expanding; 11%(1990–2006) to 34%(2011–2013).

Conclusion

There has been a reduction in the prevalence of smoking in the IBD cohort in the West. This is not consistent globally. Although, smoking prevalence has decreased in the general population of newly industrialised nations, this remains an important risk factor with longer term outcomes awaiting translation in both UC and CD.

The Impact of Inflammatory Bowel Disease in Canada 2018: Children and Adolescents with IBD

Canada has among the highest rates of childhood-onset IBD in the world. Over 7000 children and youth under 18 years old are living with IBD in Canada, and 600 to 650 children under 16 years old are diagnosed annually. While the peak age of onset of IBD is highest in the second and third decades of life, over the past two decades incidence has risen most rapidly in children under 5 years old. The treatment of children with IBD presents important challenges including therapeutic choices, risk of adverse events to medications, psychosocial impact on the child and family, increased cost of health care and the implications of the transition from pediatric to adult care. Despite the unique circumstances faced by children and their families, there is a lack of research to help understand the causes of the rising incidence and the best therapies for children with IBD. Scientific evidence—and specifically clinical trials of pharmaceuticals—are too often extrapolated from adult research. Health care providers must strive to understand the unique impact of childhood-onset IBD on patients and families, while researchers must expand work to address the important needs of this growing patient population.

Highlights

Key Summary Points

Gaps in Knowledge and Future Research Directions

Co-occurrence of Asthma and the Inflammatory Bowel Diseases: A Systematic Review and Meta-analysis

Background

Inflammatory bowel diseases (IBD) and asthma share genetic and environmental risk factors. Consequently, several observational studies have explored an association between IBD and asthma. We systematically reviewed and summarized the literature on the co-occurrence of asthma and IBD.

Methods

MEDLINE and EMBASE (to April 2017) were searched to identify observational studies on the association between asthma and IBD. Relative risks (RR) were pooled using random effects models. Heterogeneity was assessed using the I² and Cochran Q statistics. Meta-regression based on study design, source of patients (population-based vs. tertiary-care center) and study location was conducted to explain between-study heterogeneity.

Results

Eighteen studies were identified (15 Crohn’s disease, 15 ulcerative colitis (UC)). Asthma was associated with both Crohn’s disease (pooled RR 1.30, 95% confidence interval (CI) 1.16–1.47, I² = 88%) and UC (RR 1.34, 95% CI 1.24–1.44, I² = 93%). The study design and source of patients and study location explained between-study heterogeneity in Crohn’s disease, but not UC.

Conclusion

Asthma is associated with both Crohn’s disease and UC. Additional research is needed to determine if one disease influences the risk of developing the other or if the frequent co-occurrence of these diseases result from shared genetic, environmental, and microbial risk factors.

Boosting mTOR-dependent autophagy via upstream TLR4-MyD88-MAPK signalling and downstream NF-κB pathway quenches intestinal inflammation and oxidative stress injury

BACKGROUND AND AIMS

Defective autophagy has been proposed as an important event in a growing number of autoimmune and inflammatory diseases such as rheumatoid arthritis and lupus. However, the precise role of mechanistic target of rapamycin (mTOR)-dependent autophagy and its underlying regulatory mechanisms in the intestinal epithelium in response to inflammation and oxidative stress remain poorly understood.

METHODS

The levels of p-mTOR, LC3B, p62 and autophagy in mice and LPS-treated cells were examined by immunoblotting, immunohistochemistry, confocal microscopy and transmission electron microscopy (TEM). We evaluated the expression of IL-1β, IL-8, TNF-α, MDA, SOD and T-AOC by quantitative real time-polymerase chain reaction (qRT-PCR) and commercially available kits after silencing of mTOR and ATG5. In vivo modulation of mTOR and autophagy was achieved by using AZD8055, rapamycin and 3-methyladenine. Finally, to verify the involvement of TLR4 signalling and the NF-κB pathway in cells and active ulcerative colitis (UC) patients, immunofluorescence, qRT-PCR, immunoblotting and TEM were performed to determine TLR4 signalling relevance to autophagy and inflammation.

RESULTS

The mTOR-dependent autophagic flux impairment in a murine model of colitis, human intestinal epithelial cells and active UC patients is probably regulated by TLR4-MyD88-MAPK signalling and the NF-κB pathway. Silencing mTOR remarkably attenuated, whereas inhibiting ATG5 aggravated, LPS-induced inflammation and oxidative injury. Pharmacological administration of mTOR inhibitors and autophagy stimulators markedly ameliorated experimental colitis and oxidative stress in vivo.

CONCLUSIONS

Our findings not only shed light on the regulatory mechanism of mTOR-dependent autophagy, but also provided potential therapeutic targets for intestinal inflammatory diseases such as refractory inflammatory bowel disease.