Introduction

While genetic susceptibility and environmental exposures are known contributors to the pathophysiology of Inflammatory Bowel Disease (IBD), their complex gene-environment interactions (GXE) remain elusive. This systematic review aims to summarize the current evidence of GXE in IBD.

Aims & Methods

PubMed, EMBASE, Web of Science and Scopus were systematically searched from inception through July 20, 2022 to identify publications examining the interaction effect of genetic variants and environmental factors in IBD. All eligible studies were graded using the STREGA guideline.

Results

4,305 publications were identified and screened, resulting in 36 eligible studies. 17 studies reported statistically significant interactions.
NOD2-smoking interaction was most frequently investigated and showed variant-specific effects at rs2066847 regarding the risk of Crohn’s disease. Gene-smoking interactions were further identified in other IBD risk genes (ATG16L1, IL23R, and CALM3), detoxification genes (GSTP1 and ΗΜΟΧ1), smoking-associated genes (CHRNA3, CHRNA5, PPP1R3C, and BDNF), and the inflammatory cytokine (IL1B) through a candidate gene approach. Immunochip-wide interaction analyses yielded 64 smoking interacting variants.
Gene-diet interactions were observed across multiple nutritional measures, including fatty acid intake with CYP4F3 and FADS2, serum selenium with SEPHS1 and SEPSECS, potassium intake with IL21, alcohol consumption with IL12B, heme iron intake with FCGR2A and serum vitamin D with VDR.

Conclusion

Although previous studies have provided valuable insights into potential roles of GXE in the etiology of IBD, current evidence is sparse and inconclusive due to limited statistical power and lack of replication. Further studies, including genome wide environment interaction studies (GWEIS) and genotype-based nutrition/lifestyle clinical trials, are needed to unravel the missing heritability influenced by environmental exposures, and to construct personalized recommendations of lifestyle/dietary modification based on an individual genetic background.

Introduction

Inflammatory bowel disease (IBD) is a chronic recurrent inflammatory bowel disease, whose cause involves the interaction between genetic and environmental factors. At present, the pathogenesis of IBD has not been fully understood. Although there is a recognized link between immune response and IBD, the causal relationship between circulating immune cell counts and IBD remains controversial.

Aims & Methods

This study aimed to elucidate the causal relationship between genetically predicted circulating immune cell counts and IBD. We conducted a bidirectional two-sample Mendelian randomization (MR) study using aggregated statistics from genome-wide association studies. The causal relationship between five circulating leukocytes cells (monocytes, lymphocytes, eosinophils, basophils and neutrophils) counts and IBD, including Ulcerative colitis (UC) and Crohn's disease (CD) was analyzed. Inverse variance weighting (IVW) was used as the primary MR analysis method, and horizontal pleiotropy test and heterogeneity test were used to ensure the stability of the results.

Results

Our findings indicated that monocytes, lymphocytes, eosinophils, and basophils count were not significantly associated with IBD, however, elevated circulating neutrophils count was significantly associated with higher risk of IBD [odds ratio (OR): 1.002; 95% confidence interval (CI): 1.001–1.003; p = 0.009] and UC [OR: 2.465; 95%CI: 1.236–4.916; p = 0.01]. In addition, we also found that IBD [ OR: 12.07; 95% CI: 1.909-76.316; P = 0.008] and UC [OR: 2.465; 95% CI: 1.236 - 4.916; P = 0.01] were significantly associated with higher circulating neutrophils count in reverse MR.

Conclusion

This MR study provides genetic evidence for the causal relationship between the genetically predicted increase in circulating neutrophils count and the risk of IBD (UC and CD). This finding stresses the need for further exploring physiological functions of neutrophils in order to develop effective strategies against IBD.

Disclosure

The authors state that the study was conducted in the absence of any business or financial relationships that could be interpreted as potential conflicts of interest.

Introduction

Inflammatory bowel diseases (IBD) are a distinct class of gastrointestinal disorders mainly represented by Crohn’s Disease (CD) and Ulcerative Colitis (UC). The dysregulation of microRNAs (miRNAs), a class of conserved endogenous, small non-coding RNA molecules, both tissue-derived and circulating, have shown to be promising biomarkers in IBD. These biomarkers can be useful for differential diagnosis, drug response prediction and can have prognostic value for the evolution of the disease. Moreover, miRNAs are interesting tools for potential future therapeutic approaches by miRNA antagonists or mimics [1].

Aims & Methods

In this study we aimed to perform a preliminary screening of a large panel of 179 miRNAs in the plasma of 6 patients with IBD and 12 non-IBD patients (CTRL) in order to identify a set of highly dysregulated miRNAs to be investigated in a larger cohort. Isolation of miRNAs has been conducted using miRNeasy Serum/Plasma Kit and the miRNAs expression has been evaluated using the Human serum/plasma focus, MIRCURY LNA miRNA Focus PCR panel (Qiagen) by qRT-PCR. After excluding 29 miRNAs that were not expressed in the investigated samples, we identified miR-19a-3p and miR-17-5p as the most stable miRNAs by the RefFinder analysis. Thus, the Ct values of the other 148 miRNAs have been normalized against the geometric mean of these two miRNAs as endogenous controls using the 2^-DCt method. All the clinical, sociodemographic and miRNAs expression data have been analyzed using SPSS. Categorical variables were tested by means of the chi-square test, and continuous variables with t-test or the non-parametric Man Whitney test, according to the normality of the data distribution.

Results

The two groups were age matched (mean age IBD= 45.83±21.27, mean age CTRL = 50.08±8.16, p=0.543) and did not differ for sex distribution (IBD= 33.3% female, CTRL=58.3% female, χ2= 1.00 and p=0.317). The statistical analysis revealed 45 miRNAs differentially expressed (p<0.05). In particular, we identified 29 overexpressed miRNAs (miR-223-3p, miR-143-3p, let-7f-5p, miR-30b-5p, miR-26a-5p, let-7a-5p, miR-142-3p, miR-374a-5p, miR-339-5p, miR-150-5p, miR-454-3p, let-7d-5p, miR-29a-3p, miR-146a-5p, miR-199a-3p, miR-221-3p, miR-142-5p, miR-191-5p, miR-338-3p, let-7g-5p, miR-103a-3p, miR-23a-3p, miR-145-5p, miR-374b-5p, miR-24-3p, miR-107, miR-27b-3p, let-7c-5p, miR-26b-5p) in the IBD group compared with the CTRL showing a fold regulation (FR)>1.5 and 7 miRNAs underexpressed reporting a FR<-1.5 (miR-421, miR-320d, miR-106b-3p, miR-320c, miR-20b-5p, miR-320b, miR-486-5p).
Notably, the expression of let-7a-5p that was upregulated in the IBD group (FR=2.45; p=0.001) positively correlated with the years of disease duration (p=0.01, Pearson r=0.919). The same positive correlation was observed for miR-30b-5p (p=0.049, Pearson r=0.812).

Conclusion

The reported data, showing 45 miRNAs differentially expressed in the plasma of IBD patients compared to controls, represent preliminary results that must be validated. The most statistically significant dysregulated miRNAs, as well as those that correlated with the years of disease duration and other clinical parameters will be investigated in a large IBD cohort in order to examine the potential value of these miRNAs as diagnostic and prognostic biomarkers.
This investigation received financial support from ICGEB (Contract No. CRP/22/019, ICGEB Ref. No. CRP/ROU21-01)

References

1. James JP, Riis LB, Malham M, Høgdall E, Langholz E, Nielsen BS. MicroRNA Biomarkers in IBD-Differential Diagnosis and Prediction of Colitis-Associated Cancer. Int J Mol Sci. 2020 Oct 24;21(21):7893. doi: 10.3390/ijms21217893. PMID: 33114313; PMCID: PMC7660644.

Introduction

As the therapeutic armamentarium for inflammatory bowel diseases (IBD) is rapidly expanding, it is of increasing importance to optimize treatment sequencing. However, head-to-head trials comparing efficacy of vedolizumab (VDZ) in bio-naïve versus bio-experienced patients are scarce.

Aims & Methods

Aim: To compare the effectiveness of VDZ in bio-naïve versus bio-experienced patients with IBD in a real world setting.
Methods: A retrospective monocentric study was performed in IBD patients treated with VDZ at a Belgian University Hospital, from January 2018 to June 2021 with follow-up until December 2021. Primary endpoints considering efficacy after induction and after 1 year of therapy were: clinical response (CRp) and remission (CRm), biochemical response (BRp) and remission (BRm) and endoscopic response (ERp) and remission (ERm). Secondary endpoint was treatment survival during follow-up. For assessment of risk factors influencing efficacy and treatment survival, a multivariate logistic regression and Cox regression model (CRM) were applied.

Results

A total of 84 patients were treated with VDZ, 42 bio-naïve and 42 bio-experienced. At baseline, significantly more bio-experienced patients had prior intestinal resection (IR) (40.5% (17/42) vs. 16.7% (7/42), P=0.016), used an immunomodulator (IMM) (35.7% (15/42) vs. 16.7% (7/42), P=0.047) and had a longer disease duration (12.5 vs. 3.5 years, P<0.001). Bio-naïve patients had more moderate to severe comorbidities (21.4% (9/42) vs. 2.4% (1/42), P=0.007). After VDZ induction, CRp rate was higher in bio-naïve patients (60.9% (39/42) vs 39.1% (25/42), P<0.001). Multiple logistic regression analyses revealed that bio-naïve patients had a higher chance reaching CRp (aOR 14.69, 95%CI [3.12-69.14], P<0.001)(table). CRm was reached in 35.7% bio-naïve and 19% bio-experienced patients (P=0.087). No significant difference in BRp (P=0.932) or BRm (P=0.730) rate was found . A significantly higher ERp rate was seen in bio-naïve patients (90.3% (28/31) vs. 66.7% (18/27), P=0.027). Multiple logistic regression analyses showed a trend towards higher ERp rate in bio-naïve patients (aOR 4.65, [0.99-21.84], P= 0.051)(table). No significant difference was seen for ERm (32.3 % (10/31) vs. 11.1% (3/27), P=0.054). After 1 year of VDZ, CRp was significantly higher in bio-naïve patients (82.9% (34/41) vs. 62.5% (25/40), P=0.039). Multiple logistic regression analyses showed no significant difference between both groups. Univariate analyses showed significantly higher CRm rate in bio-naïve patients (70.7% (29/41) vs. 37.5% (15/40), P=0.003). After adjustment for age, disease duration, IMM use and prior IR, this difference was no longer significant. Patients without prior IR had significantly higher odds of reaching CRm (aOR 4.33,[1.13-16.59], P=0.032). No significant difference was seen for BRp (P=0.443) and BRm (P=0.313), nor for ERp (P=0.184) or ERm (P=0.061) in univariate analyses. Cox regression analysis showed significantly longer treatment survival in bio-naïve patients (aHR 2.32, [1.03-5.23], P=0.043).

Conclusion

In this tertiary real-world cohort of patients treated with VDZ, overall, a better efficacy was seen in bio-naïve compared to bio-experienced patients.

Disclosure

No conflict of interest

Introduction

Interleukin 33 (IL-33) is a pro-inflammatory cytokine that has been implicated in the pathophysiology of inflammatory bowel disease (IBD), ulcerative colitis (UC) in particular. IL-33 as a cytokine and an alarmin might evoke systemic inflammation, which could have ramifications for the functioning of the central nervous system, contributing to mood and sleep disorders. Disruptions in IL-33 concentration are well known to occur in the course of numerous psychiatric disorders as well as obstructive sleep apnea, a condition characterized by chronic low-grade inflammation and sleep fragmentation. To date, however, this protein has not been studied in relation to insomnia or poor sleep quality, frequently comorbid to chronic inflammatory and psychiatric diseases.

Aims & Methods

The study aimed to compare serum IL-33 concentrations of IBD patients and healthy controls as well as evaluate the association between the expression level of this interleukin, depression, sleep quality, and insomnia. IBD patients (n=81) and healthy controls (HC=44) were recruited. Harvey-Bradshaw index or partial Mayo were applied in the assessment of clinical disease activity for Crohn’s disease (CD) or UC respectively. Venous blood samples as well as questionnaires: Beck Depression Inventory (BDI), Epworth sleepiness scale (ESS), Athens Insomnia Scale (AIS), and Pittsburgh Sleep Quality Index (PSQI) were collected. Human IL-33 High Sensitivity Magnetic Luminex Performance Assay was used for the analysis of serum IL-33 protein concentration according to the manufacturer’s protocol. Fluorescence measurements were taken with MAGPIX, Luminex. The study has been funded by National Science Centre, Poland (2018/31/N/NZ5/03715).

Results

No differences were noted regarding IL-33 concentrations, sleep, or psychological variables between IBD patients and HC, except for sleep efficiency, which was higher in HC (p=0.004). Only in the IBD group, a positive correlation between IL-33 concentration and BDI, PSQI, and AIS (R=0.521, p=0.003; R=0.458, p=0.01; R=0.40, p=0.03), as well as negative one with sleep efficiency (R=-0.475, p=0.008) was noted. IBD individuals with high scores on ESS or PSQI (ESS>10, PSQI>5) had elevated IL-33 serum level compared to IBD patients without sleep problems (IL-33 concentration [pg/ml]: 53.385 (30.070-313.020) vs 18.795 (11.790-26.175), P=0.01 for PSQI; 270.900 (156.225-438.680) vs 21.840 (11.870-47.720), P=0.006 for ESS). IL-33 concentrations and questionnaire scores were comparable in patients with different disease activity. As for IBD types, in the CD, but not the UC group, IL-33 was positively correlated with the severity of depression symptoms and poor sleep quality (R=0.581, p=0.02; R=0.531, p=0.03) and negatively with sleep efficiency (R=-0.667, p=0.005).

Conclusion

IL-33 might be associated with mood and sleep disorders in IBD. It could exert its effect by promoting systemic and neuroinflammation, thus negatively affecting the well-being of IBD patients. Further research on the subject of changes in mental health of IBD patients in the context of anti-inflammatory or immunosuppressive treatment would be valuable.

Introduction

IL-33/ST2 axis and gut microbiota are important factors in the pathogenesis of IBD with a potential reciprocal influence. IL-33/ST2 axis controls the mucosal healing process during intestinal inflammation. Restorative proctocolectomy with ileal pouch-anal anastomosis is a surgical procedure in patients with ulcerative colitis (UC) refractory to medical therapies. Pouchitis, the most common complication, is the inflammation of the pouch with a controversial etiology.

Aims & Methods

We aimed to explore the potential role of IL-33/ST2 and gut microbiota axis in the inflammatory process of pouchitis.
30 UC patients with ileal pouch-anal anastomosis were enrolled. After clinical, endoscopic and histological assessment 18 showed pouchitis and 12 a normal pouch. Mucosal samples were collected from the afferent ileal loop and from the pouch and processed for cytokines assessment, histological evaluation and gut microbiota analyses. Multiplex analysis for inflammatory and regulatory cytokines was performed. ELISA and western blot were run to assess IL-33/ST2 protein levels and to evaluate protein isoforms, respectively. IHC was done to evaluate mucosal IL-33/ST2 expression and localization. Microbiota was analyzed by 16S ribosomal RNA gene amplicon pyrosequencing. Pouchitis Disease Activity Index and Pouchitis Histological Score were calculated, and CRP and fecal calprotectin were obtained for each patient. Multivariate analyses were run to generate transcriptional interaction networks and identify biomarkers for patients with inflamed pouches.

Results

IL-1Ra, IL-6, IL-8, IL-17, IP-10, MCP-1, MIP-1a, MIP-1b resulted increased in inflamed pouch vs. normal pouch. No differences were registered between samples obtained from the afferent ileal loop. In pouchitis, IL-7 resulted reduced in the inflamed pouch vs. the afferent ileal loop. In pouchitis, IL-33 and ST2 protein levels were reduced in the pouch vs. the afferent ileal loop and resulted overall decreased vs. patients with normal pouch indicating a potential IL-33/ST2-mediated defective healing process. Full-length, bioactive IL33, ST2L and sST2 were expressed in all experimental groups; the cleaved, less active form of IL33 was increased in only patients with pouchitis. IHC confirmed these observations. IL-33 and ST2 staining was less intense within the inflamed and ulcerated mucosa of pouchitis patients compared to normal pouch, and in close proximity to areas of re-epithelialization. An overall decreased biodiversity in patients with pouchitis vs. patients with normal pouch (both at pouch and afferent ileal loop level) was shown. Lower levels of Verrucomicrobia and increased abundance of Actinobacteria were recorded in inflamed pouch vs normal pouch. In pouchitis, the afferent ileal loop and the pouch showed significantly decreased levels of Akkermansia muciniphila and augmented abundance of Collinsella vs. samples obtained from patients with normal pouch. In pouchitis, multivariate analyses evidenced a significant inverse correlation between Collinsella e Collinsella aereofaciens abundance and ST2 levels.

Conclusion

In patients with pouchitis vs patients with normal pouch divergent inflammatory molecular pathways and microbial populations distinctly characterize the pouch and the afferent ileal loop. Overall, our results suggest a potential role for IL-33/ST2 and gut microbiota axis in driving the gut mucosal wound healing in patients with ileal pouch-anal anastomosis. Further studies are underway to determine mechanisms of action that support these findings.