Recent insights into the molecular pathogenesis of Crohn's disease: a review of emerging therapeutic targets

Impact of Dietary Patterns in Inflammatory Bowel Disease Subtypes Versus Healthy Subjects: a Retrospective Cohort Study

Objectives:Inflammatory bowel diseases (IBD) have been associated with multiple environmental factors, including diet. A dietary pattern characterized by low fiber content, high fat content and high carbohydrate content has been linked to the development of IBD. The objective of the current investigation is to examine the potential link between dietary patterns and the occurrence of IBD and to investigate whether there are any differences in relation to the type of IBD and specific food groups. Material and methods:We conducted an observational retrospective comparative study using three cohorts: 89 Crohn's disease (CD) patients, 40 ulcerative colitis (UC) patients and 64 healthy subjects. All participants underwent structured interviews and were required to complete a questionnaire regarding their dietary habits either prior to the onset of IBD or within the last year for control subjects. Results:A higher proportion of CD patients reported a higher rate of salt intake (71.9% vs. 53.1%, p-value = 0.043), sweetened beverages (38.2% vs. 17.2%, p-value=0.022), processed meat (66.3% vs. 40.6%, p-value=0.007), fatty meat (50.6% vs. 28.1%, p-value=0.021), fried foods (47.2% vs. 9.4%, p-value<0.001) and mayonnaise (21.3% vs. 6.2%, p-value=0.032) and a lower intake of nuts and seeds (20.2% vs. 43.8%, p-value=0.004) and yogurt (23.6% vs. 43.8%, p-value=0.030) compared to healthy subjects. Compared to controls, in the UC group there was a higher consumption of salt (85% vs. 53.1%, p-value=0.003), sweetened beverages (47.5% vs. 17.2%, p-value=0.005), fatty meat (55% vs. 28.1%, p-value=0.025) and fried foods (55% vs. 9.4%, p-value<0.001) and a lower intake of nuts and seeds (10% vs. 43.8%, p-value=0.001). Conclusion:Diet patterns before the onset of the disease are similar in patients with Crohn's disease and patients with ulcerative colitis: increased consumption of sweetened beverages, processed and fatty meat, fried food, salt, store-bought ice cream, and mayonnaise, and decreased intake of seeds, nuts, and yogurt.

Current clinical developments in curcumin-based therapeutics for cancer and chronic diseases

The last decade has seen an unprecedented rise in the prevalence of chronic diseases worldwide. Different mono-targeted approaches have been devised to treat these multigenic diseases, still most of them suffer from limited success due to the off-target debilitating side effects and their inability to target multiple pathways. Hence a safe, efficacious, and multi-targeted approach is the need for the hour to circumvent these challenging chronic diseases. Curcumin, a natural compound extracted from the rhizomes of Curcuma longa, has been under intense scrutiny for its wide medicinal and biological properties. Curcumin is known to manifest antibacterial, antiinflammatory, antioxidant, antifungal, antineoplastic, antifungal, and proapoptotic effects. A plethora of literature has already established the immense promise of curcuminoids in the treatment and clinical management of various chronic diseases like cancer, cardiovascular, metabolic, neurological, inflammatory, and infectious diseases. To date, more than 230 clinical trials have opened investigations to understand the pharmacological aspects of curcumin in human systems. Still, further randomized clinical studies in different ethnic populations warrant its transition to a marketed drug. This review summarizes the results from different clinical trials of curcumin-based therapeutics in the prevention and treatment of various chronic diseases.

Diet as an environmental trigger in inflammatory bowel disease: a retrospective comparative study in two European cohorts

BACKGROUND AND AIMS

inflammatory bowel disease development has been associated with several environmental factors, among which, diet can play a key role, probably due to a westernized lifestyle. However, its involvement in the pathogenesis of inflammatory bowel disease (IBD) is difficult to demonstrate. The aim of this study was to analyze dietary composition in a Romanian and Belgian population with IBD.

METHODS

an observational retrospective comparative study was performed using two European cohorts (Romanian and Belgian). The IBD group included 76 Romanian and 53 Belgian patients with an IBD diagnosis, while the control group included a total of 56 healthy people (35 Romanians and 21 Belgians). All subjects were interviewed and asked to fill in a questionnaire regarding diet.

RESULTS

in the entire IBD cohort (Romanian + Belgian), a significantly increased consumption of sweets (OR 3.36 [95 % CI 1.6,7]), processed and high fat meat (OR 2.5 [95 % CI 1.4, 4.7], fried food (OR 9.5 [3.8, 23.6]), salt (OR 2.8 [1.5, 5.3]), ice cream (OR 3.25 [1.1, 9.8]), mayonnaise (OR 3.49 [1.1, 10.3]), margarine (OR 5.63 [1.64, 19.33]) and chips/nachos/other snacks (OR 2.3 [0.97, 5.73]) were found compared to the healthy control group. The intake of seeds, nuts (OR 0.26 [0.14, 0.52]) and yoghurt consumption (OR 0.44 [0.23, 0.83]) was lower in the IBD group compared to the control group.

CONCLUSION

a westernized diet with increased consumption of sweets, processed food, high fat meat, fried food, salt, margarine, snacks, ice cream and mayonnaise seems to be a risk factor for IBD in Romanian and Belgian IBD patients. Intake of seeds, nuts and yoghurt may be a protective factor.

Saffron Pre-Treatment Promotes Reduction in Tissue Inflammatory Profiles and Alters Microbiome Composition in Experimental Colitis Mice

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract with an incompletely understood pathogenesis. Long-standing colitis is associated with increased risk of colon cancer. Despite the availability of various anti-inflammatory and immunomodulatory drugs, many patients fail to respond to pharmacologic therapy and some experience drug-induced adverse events. Dietary supplements, particularly saffron (Crocus sativus), have recently gained an appreciable attention in alleviating some symptoms of digestive diseases. In our study, we investigated whether saffron may have a prophylactic effect in a murine colitis model. Saffron pre-treatment improved the gross and histopathological characteristics of the colonic mucosa in murine experimental colitis. Treatment with saffron showed a significant amelioration of colitis when compared to the vehicle-treated mice group. Saffron treatment significantly decreased secretion of serotonin and pro-inflammatory cytokines, such as TNF-α, IL-1β, and IL-6, in the colon tissues by suppressing the nuclear translocation of NF-κB. The gut microbiome analysis revealed distinct clusters in the saffron-treated and untreated mice in dextran sulfate sodium (DSS)-induced colitis by visualization of the Bray-Curtis diversity by principal coordinates analysis (PCoA). Furthermore, we observed that, at the operational taxonomic unit (OTU) level, Cyanobacteria were depleted, while short-chain fatty acids (SCFAs), such as isobutyric acid, acetic acid, and propionic acid, were increased in saffron-treated mice. Our data suggest that pre-treatment with saffron inhibits DSS-induced pro-inflammatory cytokine secretion, modulates gut microbiota composition, prevents the depletion of SCFAs, and reduces the susceptibility to colitis.

Treatment with Molgramostim (Recombinant Human Granulocyte-Macrophage Colony Stimulating Factor, Rhugm-Csf, Mielogen) and Lenograstim (Granulocyte-Colony Stimulating Factor) Improves Experimental Colitis in Rats

Background/Aim

Treatment with growth factors could be beneficial in both inflammatory bowel disease and experimental colitis. The aim of this study was to investigate the effect of Colony Stimulating Factor (CSF), and Recombinant Human (rHu) Granulocyte Stimulating Factor (GSF) in experimental colitis in rats.

Methods

Experimental colitis was induced in 62 male Wistar rats, divided into 9 groups, using 2,4,6-trinitrobenzensulfonic acid (TNBS). Group 1: Ten rats with colitis without treatment (control group). Euthanasia after 15 days. Group 2: Ten animals with colitis without treatment (control group). Euthanasia after 30 days. Group 3: Six animals with colitis. Immediate treatment with CSF. Euthanasia after 19 days. Group 4: Six animals with colitis. Treatment started 7 days after the induction of colitis. Animals were kept for 19 days. Group 5: Six animals with colitis. Treatment started 2 weeks after the induction of colitis. Group 6: Six animals with colitis, the same as in group 3. Treatment with GSF. Group 7: Six animals with colitis, the same as in group 4. Treatment with GSF.

Group 8

Six animals with colitis, the same as in group 5. Treatment with GSF. Group 9: Six animals with colitis. Immediate treatment with prednisolone. Euthanasia after 15 days.

Results

CSF and GSF administration significantly improved the histological score (P < 0.05) and reduced malondialdehyde contents (P < 0.05), compared to control groups in all animals. CSF was superior to GSF and to prednisolone.

Conclusion

Administration of both CSF and GSF could significantly improve the histological score and oxidative stress in experimental colitis in rats.

Increased expression of kynurenine aminotransferases mRNA in lymphocytes of patients with inflammatory bowel disease

BACKGROUND

Complex interaction of genetic defects with environmental factors seems to play a substantial role in the pathogenesis of inflammatory bowel disease (IBD). Accumulating data implicate a potential role of disturbed tryptophan metabolism in IBD. Kynurenic acid (KYNA), a derivative of tryptophan (TRP) along the kynurenine (KYN) pathway, displays cytoprotective and immunomodulating properties, whereas 3-OH-KYN is a cytotoxic compound, generating free radicals.

METHODS

The expression of lymphocytic mRNA encoding enzymes synthesizing KYNA (KAT I-III) and serum levels of TRP and its metabolites were evaluated in 55 patients with IBD, during remission or relapse [27 patients with ulcerative colitis (UC) and 28 patients with Crohn's disease (CD)] and in 50 control individuals.

RESULTS

The increased expression of KAT1 and KAT3 mRNA characterized the entire cohorts of patients with UC and CD, as well as relapse-remission subsets. Expression of KAT2 mRNA was enhanced in patients with UC and in patients with CD in remission. In the entire cohorts of UC or CD, TRP levels were lower, whereas KYN, KYNA and 3-OH-KYN were not altered. When analysed in subsets of patients with UC and CD (active phase-remission), KYNA level was significantly lower during remission than relapse, yet not versus control. Functionally, in the whole groups of patients with UC or CD, the TRP/KYN ratio has been lower than control, whereas KYN/KYNA and KYNA/3-OH-KYN ratios were not altered. The ratio KYN/3-OH-KYN increased approximately two-fold among all patients with CD; furthermore, patients with CD with relapse, manifested a significantly higher KYNA/3-OH-KYN ratio than patients in remission.

CONCLUSION

The presented data indicate that IBD is associated with an enhanced expression of genes encoding KYNA biosynthetic enzymes in lymphocytes; however, additional mechanisms appear to influence KYNA levels. Higher metabolic conversion of serum TRP in IBD seems to be followed by the functional shift of KYN pathway towards the arm producing KYNA during exacerbation. We propose that KYNA, possibly via interaction with aryl hydrocarbon receptor or G-protein-coupled orphan receptor 35, may serve as a counter-regulatory mechanism, decreasing cytotoxicity and inflammation in IBD. Further longitudinal studies evaluating the individual dynamics of TRP and KYN pathway in patients with IBD, as well as the nature of precise mechanisms regulating KYNA synthesis, should be helpful in better understanding the processes underlying the observed changes.

Colonic Epithelial Surfactant Protein D Expression Correlates with Inflammation in Clinical Colonic Inflammatory Bowel Disease

BACKGROUND

Inflammatory bowel diseases (IBD) are chronic disorders of the gastrointestinal tract. Surfactant protein D (SP-D) is expressed in the intestinal epithelium and is essential for innate host defense and regulation of inflammatory responses. Genetic variations of SP-D are associated with IBD, but the effects of SP-D in clinical disease development have not been clarified. We hypothesized that colonic epithelial SP-D expression is increased in parallel with intestinal inflammation with the capacity to dampen deleterious effects.

METHODS

Surgical specimens from IBD patients including Crohn's disease (n = 9) and ulcerative colitis (n = 18) were scored for expression of SP-D and inflammatory activity. Cohoused Sftpd+/+ and Sftpd-/- mouse littermates were subjected to dextran sodium sulfate (DSS) for 7 days to induce colitis. Colonic tissue was scored for histologic damage and analyzed for inflammatory markers and expression of SP-D.

RESULTS

Surgical specimens from IBD patients showed a strong positive correlation between immunoscore for SP-D and inflammatory activity (R2 = 0.78, P < 0.0001). In mice, colonic epithelial SP-D expression was very low, and DSS-induced colitis was unaffected by SP-D deficiency, although DSS induced transcription of colonic SP-D to a mild degree.

CONCLUSIONS

A strong positive correlation between inflammatory activity and epithelial expression of SP-D was observed in surgical specimens from IBD patients supporting a role for SP-D in clinical disease. The in vivo study was inconclusive due to very low intestinal SP-D expression in the mouse. Further studies are warranted to support that increased SP-D expression in the human colonic epithelium is protective against intestinal inflammation.

Multi-omic analysis of signalling factors in inflammatory comorbidities

BACKGROUND

Inflammation is a core element of many different, systemic and chronic diseases that usually involve an important autoimmune component. The clinical phase of inflammatory diseases is often the culmination of a long series of pathologic events that started years before. The systemic characteristics and related mechanisms could be investigated through the multi-omic comparative analysis of many inflammatory diseases. Therefore, it is important to use molecular data to study the genesis of the diseases. Here we propose a new methodology to study the relationships between inflammatory diseases and signalling molecules whose dysregulation at molecular levels could lead to systemic pathological events observed in inflammatory diseases.

RESULTS

We first perform an exploratory analysis of gene expression data of a number of diseases that involve a strong inflammatory component. The comparison of gene expression between disease and healthy samples reveals the importance of members of gene families coding for signalling factors. Next, we focus on interested signalling gene families and a subset of inflammation related diseases with multi-omic features including both gene expression and DNA methylation. We introduce a phylogenetic-based multi-omic method to study the relationships between multi-omic features of inflammation related diseases by integrating gene expression, DNA methylation through sequence based phylogeny of the signalling gene families. The models of adaptations between gene expression and DNA methylation can be inferred from pre-estimated evolutionary relationship of a gene family. Members of the gene family whose expression or methylation levels significantly deviate from the model are considered as the potential disease associated genes.

CONCLUSIONS

Applying the methodology to four gene families (the chemokine receptor family, the TNF receptor family, the TGF- β gene family, the IL-17 gene family) in nine inflammation related diseases, we identify disease associated genes which exhibit significant dysregulation in gene expression or DNA methylation in the inflammation related diseases, which provides clues for functional associations between the diseases.

Differential Intestinal Mucosa Transcriptomic Biomarkers for Crohn's Disease and Ulcerative Colitis

Genetic research has shaped the inflammatory bowel disease (IBD) landscape identifying nearly two hundred risk loci. Nonetheless, the identified variants rendered only a partial success in providing criteria for the differential diagnosis between ulcerative colitis (UC) and Crohn's disease (CD). Transcript levels from affected intestinal mucosa may serve as tentative biomarkers for improving classification and diagnosis of IBD. The aim of our study was to identify gene expression profiles specific for UC and CD, in endoscopically affected and normal intestinal colonic mucosa from IBD patients. We evaluated a panel of 84 genes related to the IBD-inflammatory pathway on 21 UC and 22 CD paired inflamed and not inflamed mucosa and on age-matched normal mucosa from 21 non-IBD controls. Two genes in UC (CCL11 and MMP10) and two in CD (C4BPB and IL1RN) showed an upregulation trend in both noninflamed and inflamed mucosa compared to controls. Our results suggest that the transcript levels of CCL11, MMP10, C4BPB, and IL1RN are candidate biomarkers that could help in clinical practice for the differential diagnosis between UC and CD and could guide new research on future therapeutic targets.

Association between Toll-Like Receptor 4 T399I Gene Polymorphism and the Susceptibility to Crohn's Disease: A Meta-Analysis of Case-Control Studies

BACKGROUND/AIMS

This article was undertaken to investigate the association of toll-like receptor 4 (TLR4) polymorphism (Thr399Ile) and risk of Crohn's disease (CD) by performing a meta-analysis.

METHODS

Articles were chosen based on PubMed, Embase, China National Knowledge Internet, and Chinese Wanfang databases (up to 12th October 2016). Specific inclusion criteria were used to evaluate articles. Meta-analysis was performed by using a random or fixed effect model. Fifteen eligible case-control studies were finally included into this meta-analysis. We estimated the summary OR with its corresponding 95% CI to assess the association.

RESULTS

Summary results of this meta-analysis showed a moderate association between the TLR4 T399I polymorphism and the risk of CD (allele model: OR 1.26, 95% CI 1.06-1.50, p = 0.009; heterozygote model: OR 1.36, 95% CI 1.11-1.66, p = 0.003; dominant model: OR 1.35, 95% CI 1.10-1.64, p = 0.004; homozygote model: OR 1.08, 95% CI 0.44-2.64, p = 0.866; recessive model: OR 0.97, 95% CI 0.40-2.35, p = 0.946). Stratified analysis on geographical area, ethnicity, and genotypic methods suggested that the polymorphism was associated with increased risk of CD in Asia and Asians, and "T" allele only moderately increased CD risk within polymerase chain reaction-restricted fragment length polymorphism.

CONCLUSIONS

Our meta-analysis suggests that TLR4 T399I polymorphism is moderately associated with susceptibility to CD, and more studies are needed to confirm our conclusion.

Role of PTPN2/22 polymorphisms in pathophysiology of Crohn's disease

AIM

To establish the relationship of protein tyrosine phosphatase non-receptor type 2 and 22 (PTPN2/22) polymorphisms and mycobacterial infections in Crohn's disease (CD).

METHODS

All 133 subjects' blood samples were genotyped for nine single nucleotide polymorphisms (SNPs) in PTPN2/22 using TaqMan™ genotyping, while the effect of the SNPs on PTPN2/22 and IFN-γ gene expression was determined using RT-PCR. Detection of Mycobacterium avium subspecies paratuberculosis (MAP) IS900 gene was done by nPCR after DNA extraction from the isolated leukocytes of each subjects' blood samples. T-cells isolated from the patient samples were tested for response to phytohematoagglutonin (PHA) mitogen or mycobacterial antigens by BrdU proliferation assays for T-cell activity.

RESULTS

Out of the nine SNPs examined, subjects with either heterozygous (TC)/minor (CC) alleles in PTPN2:rs478582 occurred in 83% of CD subjects compared to 61% healthy controls (P-values < 0.05; OR = 3.03). Subjects with either heterozygous (GA)/minor (AA) alleles in PTPN22:rs2476601 occurred in 16% of CD compared to 6% healthy controls (OR = 2.7). Gene expression in PTPN2/22 in CD subjects was significantly decreased by 2 folds compared to healthy controls (P-values < 0.05). IFN-γ expression levels were found to be significantly increased by approxiately 2 folds in subjects when either heterozygous or minor alleles in PTPN2:rs478582 and/or PTPN22:rs2476601 were found (P-values < 0.05). MAP DNA was detected in 61% of CD compared to only 8% of healthy controls (P-values < 0.05, OR = 17.52), where subjects with either heterozygous or minor alleles in PTPN2:rs478582 and/or PTPN22:rs2476601 had more MAPbacteremia presence than subjects without SNPs did. The average T-cell proliferation in CD treated with PHA or mycobacteria antigens was, respectively, 1.3 folds and 1.5 folds higher than healthy controls without any significant SNP.

CONCLUSION

The data suggests that SNPs in PTPN2/22 affect the negative regulation of the immune response in CD patients, thus leading to an increase in inflammation/apoptosis and susceptibility of mycobacteria.

Curcumin, the golden nutraceutical: multitargeting for multiple chronic diseases

Curcumin, a yellow pigment in the Indian spice Turmeric (Curcuma longa), which is chemically known as diferuloylmethane, was first isolated exactly two centuries ago in 1815 by two German Scientists, Vogel and Pelletier. However, according to the pubmed database, the first study on its biological activity as an antibacterial agent was published in 1949 in Nature and the first clinical trial was reported in The Lancet in 1937. Although the current database indicates almost 9000 publications on curcumin, until 1990 there were less than 100 papers published on this nutraceutical. At the molecular level, this multitargeted agent has been shown to exhibit anti-inflammatory activity through the suppression of numerous cell signalling pathways including NF-κB, STAT3, Nrf2, ROS and COX-2. Numerous studies have indicated that curcumin is a highly potent antimicrobial agent and has been shown to be active against various chronic diseases including various types of cancers, diabetes, obesity, cardiovascular, pulmonary, neurological and autoimmune diseases. Furthermore, this compound has also been shown to be synergistic with other nutraceuticals such as resveratrol, piperine, catechins, quercetin and genistein. To date, over 100 different clinical trials have been completed with curcumin, which clearly show its safety, tolerability and its effectiveness against various chronic diseases in humans. However, more clinical trials in different populations are necessary to prove its potential against different chronic diseases in humans. This review's primary focus is on lessons learnt about curcumin from clinical trials.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Does Gastric Surgery (Such as Bariatric Surgery) Impact the Risk of Intestinal Inflammation?

Background

The prevalence of morbid obesity and inflammatory bowel disease (IBD) is on the rise in association with a Western lifestyle. Both conditions are characterized by chronic inflammation. Bariatric surgery (BS) is a recommended and widely used approach to address severe obesity and its related comorbidities. Roux-en-Y gastric bypass (RYGBP) and sleeve gastrectomy (SG) are the most frequently performed procedures worldwide. Evidence is scarce on outcomes of BS in IBD patients.

Summary

Systemic and adipose-tissue inflammation seems to decrease following BS. Different studies observed decreased serum levels of inflammatory markers (CRP, IL-6, MCP-1, and TNF-α) along with a reduction of insulin resistance both after RYGBP and SG. Several authors documented postbariatric improvement of concomitant chronic inflammatory diseases (rheumatoid arthritis, systemic lupus erythematosus, gout, and psoriasis). There are only few retrospective case series on outcomes of BS in IBD patients. These studies reported safety and feasibility of BS and improvement in IBD status, manifested by prolonged disease remission and decreased use of pharmacotherapy. Weight loss outcomes were excellent and similar to those of non-IBD patients. The preferred surgical approach for morbidly obese IBD patients is SG in order to avoid potential drawbacks of RYGBP, such as malabsorption, intestinal manipulation, and augmentation of technical difficulties for future IBD surgery. Seven cases of newly diagnosed IBD after BS have been reported, which are more likely to result from postoperative intestinal microbial dysbiosis than from directly induced inflammation.

Key Messages

This review summarizes the outcomes of BS in IBD patients. SG is the preferable technique for morbidly obese IBD patients, who have potentially a double benefit from BS: weight loss and IBD remission. Further research is necessary to clarify the common pathophysiology of chronic inflammation in morbid obesity and in IBD. Postbariatric changes in gut microbiota should also be assessed to understand whether they promote IBD development or not.

Correlations of Host Genetics and Gut Microbiome Composition

The human gut microbiome has a considerable impact on host health. The long list of microbiome-related health disorders raises the question of what in fact determines microbiome composition. In this review we sought to understand how the host itself impacts the structure of the gut microbiota population, specifically by correlations of host genetics and gut microbiome composition. Host genetic profile has been linked to differences in microbiome composition, thus suggesting that host genetics can shape the gut microbiome of the host. However, cause-consequence mechanisms behind these links are still unclear. A survey of the possible mechanisms allowing host genetics to shape microbiota composition in the gut demonstrated the major role of metabolic functions and the immune system. A considerable impact of other factors, such as diet, may outweigh the effects of host genetic background. More studies are necessary for good understanding of the relations between the host genetic profile, gut microbiome composition, and host health. According to the idea of personalized medicine, patient-tailored management of microbiota content remains a fascinating area for further inquiry.

Enteric Neuronal Regulation of Intestinal Inflammation

Recent research has highlighted the importance of the two-way interaction between the nervous and immune systems. This interaction is particularly important in the bowel because of the unique properties of this organ. The lumen of the gut is lined by a very large but remarkably thin surface that separates the body from the enteric microbiome. Immune defenses against microbial invasion are thus well developed and neuroimmune interactions are important in regulating and integrating these defenses. Important concepts in the phylogeny of neuroimmunity, enteric neuronal and glial regulation of immunity, changes that occur in the enteric nervous system during inflammation, the fundamental role of serotonin (5-HT) in enteric neuroimmune mechanisms, and future perspectives are reviewed.