Introduction

Irritable bowel syndrome is characterized by colonic hypersensitivity (CHS) and comorbidities such as anxiety or depression. When IBS occurs following a gastrointestinal infection, it is called post-infectious IBS. These patients present abdominal pain months or years after infection resolution. Citrobacter rodentium infection in mice leads to the development of IBS-like symptoms as CHS, anxiety-like behavior and cognitive impairment 8 days after pathogen clearance. Moreover, recent data have shown that the induction of colonic IL-22 expression during the post-infectious phase allows the correction of IBS-like symptoms induced by C. rodentium infection.

Aims & Methods

Our first objective was to study the overtime chronicization of PI-IBS symptoms in this C. rodentium infection mouse model. In addition, since, the cytokine IL-22 is involved in C. rodentium clearance via regulation of Reg3γ antimicrobial peptide expression, the second objective was to evaluate the effect of Reg3γ expression on IBS-like symptoms in C. rodentium-infected mice.
Wild-type C57Bl6/J mice were infected with C. rodentium reference strain DBS100. Colonic sensitivity and anxiety- or depression-like behaviors were evaluated by colorectal distension (CRD) and several behavioral reference tests, respectively, at different days post-infection (DPI): 24, 42, 56, 84 or 112. In addition, a treatment with IL-22 or Reg3γ colonic vectorization expression were evaluated on IBS-like symptoms. This treatment was administered daily between 16 and 24 DPI, using a Lactococcus lactis strain allowing Reg3γ (L. lactis^Reg3γ) or IL-22 (L. lactis^IL-22) expression in the colonic mucosa. The fecal microbiota was also analyzed by 16S rRNA sequencing.

Results

CHS persisted in a subgroup of C. rodentium infected mice until 84 DPI, despite anxiety-like behavior was observed only until 42 DPI. No cognition impairment was noticed after 24 DPI. However, several post-infected animals developed depressive-like behavior at 42 DPI, which persisted over time. Finally, L. lactis^IL-22 and L. lactis^Reg3γ treatments corrected CHS and anxiety-like behavior induced by C. rodentium infection at 24 DPI. In addition, fecal microbiota sequencing data suggested that Reg3γ-colonic induced expression, like IL-22, modified the microbiota composition in the PI-IBS model. The effectiveness of Reg3γ delivery on long-term depressive-like behavior symptoms is being evaluated.

Conclusion

C. rodentium infection induced long-term IBS-like symptoms as chronic CHS associated with transient anxiety- and depression-like behaviors which is consistent with clinical symptoms observed in PI-IBS patients. Moreover, these initial data suggest that recovery of PI-IBS symptoms correlated with the correction of gut dysbiosis and that Reg3γ would represent an interesting therapeutic target to relieve these IBS-like symptoms.

Introduction

Irritable bowel syndrome (IBS) is one of the most prevalent chronic disorders worldwide, with considerable social and economic burden. Gut microbiome impairment is one of the potential pathogenic pathways of IBS, especially in its post-infectious form (PI-IBS).
To date, untargeted therapeutic microbiome modulation (i.e. probiotics, antibiotics, FMT) has achieved conflicting results in patients with dysbiosis-associated chronic disorders, including IBS and PI-IBS,while the inter-individual variability and the plasticity of gut microbiome supports its personalized manipulation.
In this study we performed microbiome-profiling in order to have a precision, microbiome-based approach to PI-IBS.

Aims & Methods

This is a pilot prospective, single-center, case-control study. Our aim was to describe outcomes of targeted microbiome modulation, informed by gut microbiome testing, in patients with PI-IBS referred to our Microbiome clinic, compared with a control group including PI-IBS patients managed at our General Gastroenterology outpatient clinic. PI-IBS was diagnosed according to Rome IV criteria.
Cases included patients treated in our Microbiome Clinic according to their gut microbiome testing. At baseline visit, a commercial stool microbiome testing based on 16S rRNA sequencing was prescribed. After test results, each patient received a personalized treatment to target gut microbial defects. Specifically, in the presence of increased abundance of pathobionts, or overgrowth of non-symbiont taxa, we envisaged their direct suppression by nonabsorbable antibiotics (rifaximin, neomycin-bacitracin, paromomycin) or went for the increase of beneficial taxa to enable microbial competition against them, using pre- or probiotics. In the case of low α-diversity and/or decreased abundance of specific beneficial taxa we prescribed pre- and/or probiotics to upregulate them, depending on the specific defect. When relevant, based on their microbial profile, patients received antibiotics before pre- and/or probiotics.
Controls included patients managed at our General Gastroenterology outpatient clinic who received empirical treatment according to physician’s choice.
All patients were evaluated with the IBS symptom severity scale (IBS-SSS) at baseline and after the end of treatments (±7 days). Response to treatments was defined as decrease in IBS-SSS score ≥50 points.

Results

Overall, 33 patients (13 cases and 20 controls) were enrolled. The two populations were homogeneous in terms of IBS subtypes and baseline IBS-SSS scores. Overall, the type and duration of treatments did not differ significantly between the two groups. Traditional dietary advices for IBS, without specific nutritional counselling, were given in both groups.
All patients in the group of cases (100%) and 11 of 20 patients in the control group (55%) experienced treatment response (decrease in IBS-SSS score ≥ 50 points), with a significant difference between groups (p< 0.0001). The mean IBS-SSS score after treatments was 163 in cases and 231 in controls (p= 0.01). The mean reduction in IBS-SSS score was 167 in cases and 74 in the control group (p= 0.001). Compared with controls, cases experienced significantly lower IBS-SSS subscores after treatments for satisfaction of bowel habits (p= 0.03), bloating (p= 0.04) and quality of life (p= 0.009).

Conclusion

This pilot study represents the first microbiome-based and personalized approach to PI-IBS. Our preliminary findings suggest that targeted microbial modulation, informed by microbiome profiling, might be effective in managing PI-IBS

References

1. Porcari S, Ingrosso MR, Maida M, et al. Prevalence of irritable bowel syndrome and functional dyspepsia after acute gastroenteritis: systematic review and meta-analysis. Gut. 2024;73:1431-1440.
2. Goodoory VC, Khasawneh M, Black CJ, et al. Efficacy of Probiotics in Irritable Bowel Syndrome: Systematic Review and Meta-analysis. Gastroenterology. 2023;165:1206-1218.
3. Ratiner K, Ciocan D, Abdeen SK, et al. Utilization of the microbiome in personalized medicine. Nat Rev Microbiol. 2024;22:291-308.
4. Porcari S, Mullish BH, Asnicar F, et al. International consensus statement on microbiome testing in clinical practice. Lancet Gastroenterol Hepatol. 2025;10:154-167.
5. Drossman DA, Hasler WL. Rome IV-Functional GI Disorders: Disorders of Gut-Brain Interaction. Gastroenterology. 2016;150:1257-1261.
6. Francis CY, Morris J, Whorwell PJ. The irritable bowel severity scoring system: a simple method of monitoring irritable bowel syndrome and its progress. Aliment Pharmacol Ther. 1997;11:395-402.
7. Soldi S, Vasileiadis S, Uggeri F, et al. Modulation of the gut microbiota composition by rifaximin in non-constipated irritable bowel syndrome patients: a molecular approach. Clin Exp Gastroenterol. 2015;8:309-325.

Disclosure

None

Introduction

Gut microbiome alterations are known to be one of the pathogenic pathways of irritable bowel syndrome (IBS), mainly in its post-infectious form (PI-IBS) ¹. To date, untargeted therapeutic approaches have obtained conflicting results in patients with PI-IBS ^2,3
Gut microbiome testing are emerging as a promising diagnostic tool to target microbiota and offer a personalized therapeutic strategy, but their real value is still unknown.

Aims & Methods

Our aim is to evaluate whether a personalized approach based on gut microbiome testing is an effective strategy for PI-IBS.
In this pilot study, we included consecutive patients with PI-IBS, diagnosed according to the Rome IV guidelines⁴, referring at our outpatient microbiome clinic in 2022.
All patients underwent a commercially available stool microbiome testing (XMICROGem from XBIOGem) based on 16S rRNA analysis and performed as already described⁵. Then, patients received a targeted therapy based on results of the gut microbiome testing, with the aim of restoring balance among the bacterial subpopulations of the gut microbiota. Non-adsorbable antibiotics were used to downregulate the abundance of pathobionts, while prebiotics and probiotics were given to boost the abundance of specific taxa and/or to compete with gut pathobionts. Patients were followed up to 12 weeks after the end of therapy.
We collected the following data of patients: age, gender, presence of gastrointestinal (GI) symptoms (assessed with the GSRS); specific characteristics of gut microbiome (alpha diversity, abundance of Proteobacteria, Firmicutes, Bacteroidetes, Bifidobacteria, Lactobacilli, Akkermansia, and short-chain fatty acid producers including Lachnospiraceae, Faecalibacterium, Roseburia, Butyrivibrio); specific therapy given after testing, including non-adsorbable antibiotics, prebiotics, and probiotic strains. The primary outcome was the resolution of at list one symptom, while secondary outcomes were the resolution of more than one (if present) and all of them at 12 weeks.

Results

Thirteen patients were enrolled in the study period (8 males, 5 females, mean age 31 years-old). Of them, 9 (69%) had IBS-D and 4 (31%) IBS-C. Nine patients (69%) had bloating, and 10 (71%) had abdominal pain at baseline. At gut microbiome testing: three (23%) patients presented with low alpha diversity, three (23%) with high abundance of Proteobacteria, five (38%) of Firmicutes. Seven (54%) patients presented with low abundance of SCFA-producing bacteria, eight (62%) of Akkermansia and nine (69%) of Bifidobacteria.
Patients were treated with the following non-adsorbable antibiotics: rifaximin in nine (69%) patients, and paromomicin in four (31%) patients. The following prebiotics and probiotic strains were used after antibiotics: multispecies probiotics in five patients (38%), Bifidobacterium-based probiotics in five patients (38%), Lactobacillus-based probiotics in eight patients (54%), and Escherichia coli Nissle 1917 in 2 (15%) patients; inulin and psyllium were used in nine (69%) patients.
At 12-week follow-up, 12 patients (93%) experienced an improvement of symptoms, with five of them (38%) experiencing a total remission of symptoms.

Conclusion

A precision medicine approach based on gut microbiome testing may be a promising strategy to treat PI-IBS. Well designed, randomized and larger studies are needed to confirm our preliminary findings.

References

1. Downs, I. A., Aroniadis, O. C., Kelly, L. & Brandt, L. J. Postinfection Irritable Bowel Syndrome: The Links Between Gastroenteritis, Inflammation, the Microbiome, and Functional Disease. J Clin Gastroenterol 51, 869–877 (2017).
2. Lee, Y. Y., Annamalai, C. & Rao, S. S. C. Post-Infectious Irritable Bowel Syndrome. Curr Gastroenterol Rep 19, 56 (2017).
3. Jin, Y. et al. Beneficial effects of Rifaximin in post-infectious irritable bowel syndrome mouse model beyond gut microbiota. J Gastroenterol Hepatol 33, 443–452 (2018).
4. Drossman, D. A. Functional Gastrointestinal Disorders: History, Pathophysiology, Clinical Features, and Rome IV. Gastroenterology 150, 1262-1279.e2 (2016).
5. De Maio, F. et al. Characterization of gut microbiota in patients with metabolic syndrome candidates for bariatric/metabolic surgery: Preliminary findings of a multi-center prospective study. Diabetes Res Clin Pract 180, 109079 (2021).

Disclosure

G.I. has received personal fees for acting as speaker for Biocodex, Danone, Sofar, Malesci, Metagenics and Tillotts Pharma, and for acting as consultant and/or advisor for Ferring Therapeutics, Giuliani, Malesci and Tillotts Pharma.
A.G. reports personal fees for consultancy from Eisai Srl, 3PSolutions, Real Time Meeting, Fondazione Istituto Danone, SinergieSrl, Board MRGE and Sanofi SpA personal fees for acting as a speaker for Takeda SpA, AbbVie and Sandoz SpA and personal fees for acting on advisory boards for VSL3 and Eisai.
G.C. has received personal fees for acting as advisor for Ferring Therapeutics.
All other authors have no conflicts of interest to disclose.

Introduction

Irritable Bowel Syndrome (IBS) is a complex gastrointestinal functional disorder characterized by abdominal pain or discomfort and altered bowel habits. Despite its prevalence, and often chronic relapsing nature, the underlying pathophysiology of IBS remains incompletely understood. The etiology is likely multifactorial. Chronic low-grade subclinical inflammation has been implicated in the disease process and thought to perpetuate the symptoms of IBS.
Through previous studies on the serum proteomic profiles of IBS patients, it was seen that some inflammatory proteins are overexpressed in IBS, giving rise to a different serum proteome signature in IBS compared to healthy controls. [1,2] Systemic inflammatory protein profiles have also been used to distinguish patients with ulcerative colitis from IBS patients. [3] This suggests that proteomic profiling can potentially give us more insight into understanding the inflammatory mechanisms driving IBS.

Aims & Methods

This study aims to determine if systemic inflammatory protein profiles differ between patients with IBS and healthy controls.
Serum inflammatory proteins from 42 asymptomatic healthy controls undergoing screening colonoscopy with no colonic pathology, and 41 IBS patients fulfilling ROME IV criteria were analyzed using the Olink Target 96 Inflammation Panel. A partial-least square discriminant analysis was undertaken to identify additional discriminative inflammatory proteins. Univariate t-test analyses, with false discovery rate correction, were also performed to identify proteins unique to varying subtypes of IBS.

Results

Among IBS patients, the mean age was 48.6 years (SD +/- 15.5), while 31.7% were male. Among the controls, the mean age was 61.6 years (SD +/- 7) and 50% were male. There were 18 (43.9%), 14 (34.1%), 8 (19.5%) and 1 (2.4%) IBS patients with IBS-D, IBS-M, IBS-C and IBS-U respectively. 73.2% of IBS patients and 90.5% of controls were Chinese, with the rest being Indians, Malays or others.
Majority of the proteins (n=88, 96%) were prevalent in >40% of the study participants. Of which, 6 proteins (AXIN1, CCL19, CCL28, CD8A, EN-RAGE, MMP10) were differentially abundant (p<0.05) in IBS patients. Participants with IBS-C displayed higher levels of CD8A, while participants with IBS-D showed higher levels of AXIN1 and EN-RAGE (Table 1).
Interestingly, a recent study showed that CCL28 is elevated in IBS patients, which is consistent with our findings. [4] EN-RAGE has also been studied to be elevated in several digestive diseases including IBS, inflammatory bowel disease, digestive tract cancers, necrotizing enterocolitis and gastroenteritis. [5]

Table 1: Differentially abundant immunoproteins in IBS

Conclusion

We conclude that the serum cytokine profiles of IBS patients differ from that of healthy controls. We identified 6 immunoproteins that distinguish IBS from controls, and found that the levels of these immunoproteins also differ amongst the IBS subtypes. As this was a pilot study, the data collected was preliminary and limited by a small sample size. Future larger scale studies on proteomic profiling can potentially help with understanding the immune dysregulatory mechanisms driving IBS, and guide the diagnosis of and differentiation between subtypes.

References

[1] Tsigaridas A, Anagnostopoulos AK, Papadopoulou A, Ioakeim S, Vaiopoulou A, Papanikolaou IS, Viazis N, Karamanolis G, Mantzaris GJ, Tsangaris GT, Gazouli M. Identification of serum proteome signature of irritable bowel syndrome: Potential utility of the tool for early diagnosis and patient's stratification. J Proteomics. 2018 Sep 30;188:167-172.
[2] Darkoh C, Comer L, Zewdie G, Harold S, Snyder N, Dupont HL. Chemotactic chemokines are important in the pathogenesis of irritable bowel syndrome. PLoS One. 2014 Mar 25;9(3):e93144.
[3] Moraes L, Magnusson MK, Mavroudis G, Polster A, Jonefjäll B, Törnblom H, Sundin J, Simrén M, Strid H, Öhman L. Systemic Inflammatory Protein Profiles Distinguish Irritable Bowel Syndrome (IBS) and Ulcerative Colitis, Irrespective of Inflammation or IBS-Like Symptoms. Inflamm Bowel Dis. 2020 May 12;26(6):874-884.
[4] Sheikhesmaili F, Jalili A, Taghizadeh E, Fakhari S, Jalili K, Ghaderi E, Rahimi E. The CCL28 levels are elevated in the serum of patients with irritable bowel syndrome and associated with the clinical symptoms. Am J Clin Exp Immunol. 2021 Feb15;10(1):23-29.
[5] Carvalho A, Lu J, Francis JD, Moore RE, Haley KP, Doster RS, Townsend SD, Johnson JG, Damo SM, Gaddy JA. S100A12 in Digestive Diseases and Health: A Scoping Review. Gastroenterol Res Pract. 2020 Feb 26;2020:2868373

Introduction

Irritable bowel syndrome (IBS) is a multifactorial disorder characterized by recurrent abdominal pain associated with defecation or a change in bowel habits. The pathophysiology of IBS involves alterations in the epithelial barrier, but data on the intestinal vascular barrier are lacking.

Aims & Methods

The aims of this study were to investigate the morpho-functional integrity of the vascular barrier and to correlate barrier dysfunction with IBS symptoms. Forty-eight healthy subjects (AC) and 144 patients with IBS (61 IBS-D, 51 IBS-C and 32 IBS-M) were enrolled in the study. Rome IV criteria, Bowel disease questionnaire, Short Form 12, Hospital Anxiety Depression Scale were used to phenotype patients. Immunohistochemistry, western blot and electron microscopy were used to characterize the vascular barrier. Vascular permeability was evaluated by assessing two markers: plasmalemma vesicle–associated protein-1 (PV1) and vascular endothelial cadherin (VEC). A translational model based on HUVEC was used to evaluate permeability changes induced by mediators spontaneously released by mucosal biopsies, and to highlight the underlying molecular mechanisms. Correlation analyses between experimental and clinical data were performed.

Results

Mucosal vessel density was significantly increased by 1.5 fold in the colonic mucosa of IBS patients compared to AC (P<0.01). PV1 expression was increased (P<0.01) while VEC expression was decreased in the colonic mucosa of IBS patients compared to AC (P<0.05). Compared to AC, IBS mucosal mediators increased permeability in the HUVEC monolayer through the activation of protease-activated receptor (PAR)-2 and histone deacetylase (HDAC)11, resulting in VEC downregulation. PV1 expression significantly correlated with anxiety and depression scores and health-related quality of life reported by IBS patients.

Conclusion

The vascular barrier is impaired in IBS and contributes to clinical manifestations

Introduction

Irritable bowel syndrome (IBS) is a disorder of brain-gut interaction often accompanied by psychiatric and/or somatic comorbidities. Intestinal barrier dysfunction has long been hypothesised to be a key player in IBS pathophysiology. However, it is unknown how psychiatric and somatic comorbidities affect intestinal barrier dysfunction. This study aims to assess intestinal barrier function in a large multicentric cohort of adult IBS patients with and without psychiatric/somatic comorbidities.

Aims & Methods

IBS patients (Rome IV) with (N=197) and without (N=171) comorbidities, and healthy volunteers (N=23), were included in six European hospitals. Intestinal permeability (IP) was assessed in vivo with the lactulose-mannitol-sucralose test (LMS) and ex vivo in colonic biopsies using Ussing chambers. Sugar concentrations in the urine were assessed through HPLC-ELSD and GC-MS. The L/M ratio after 2 hours was used as an estimation of the small intestinal permeability, and the %S excreted and the S/M ratio from 2 to 24 hours, for colonic permeability. Colonic biopsies were collected from 17 controls and 18 IBS patients and mounted in Ussing chambers to measure the paracellular permeability to FITC-dextran (4 kDa).

Results

When compared with healthy controls, L/M ratio did not differ in IBS patients with (p=0.33) or without comorbidities (p=0.44). Moreover, the %S excreted and S/M were not altered in IBS patients with (respectively p=0.3 and p=0.09) and without (p=0.14, p=0.1) comorbidities. Interestingly, when comparing results from IBS patients among recruiting hospitals in different parts of Europe, significant differences were found in L/M ratio (p<0.0001), %S (p<0.0001), and S/M ratio (p<0.0001). Lastly, paracellular permeability assessed ex vivo in colonic biopsies was not different between IBS patients and controls (p=0.46).

Conclusion

These results suggest that psychiatric and somatic comorbidities do not alter small intestinal and colonic permeability in IBS patients. Interestingly, our results highlight a strong variability between IBS patients from different countries, which may be explained by lifestyle, environmental, and genetic factors. Further investigations are needed to better understand these findings.

Disclosure

no conflicts of interest

Introduction

Irritable bowel syndrome (IBS) is a complex multifactorial disorder characterized by recurrent abdominal pain associated with defecation or a change in bowel habits. Patients with IBS often complain of extra-intestinal symptoms resulting in impaired related quality of life. Growing evidence support the hypothesis that intestinal barrier dysfunction has a central role in the pathophysiology of IBS being the interface between the gut lumen and the deeper intestinal layers as well as the brain.

Aims & Methods

The aims of this study were: to characterize the epithelial and vascular barriers; to correlate molecular, morphological and functional aspects of epithelial and vascular barriers with IBS symptoms. 66 healthy subjects (AC) and 223 patients with IBS (112 IBS-D, 58 IBS-C and 53 IBS-M) were enrolled in the study. Rome IV criteria, Bowel disease questionnaire, Short Form 36, Hospital Anxiety Depression Scale were used to phenotype patients. Sugar test was used to evaluate in vivo permeability. The vascular barrier was characterized by using immunohistochemistry, western blot and electron microscopy. Vascular permeability was evaluated by assessing two markers: plasmalemma vesicle–associated protein-1 (PV1) and vascular endothelial cadherin (VEC). A translational model based on Caco-2 cells or HUVEC was used to evaluate permeability changes induced by mediators spontaneously released by mucosal biopsies and to highlight the underlying molecular mechanisms. Correlation analyses have been performed among experimental and clinical data.

Results

Compared to AC, lactulose (P<0.05), sucralose (P<0.01), sucrose (P<0.01) excretion and the L/M ratio (P<0.01) were significantly increased in IBS patients. Soluble mediators released by mucosal biopsies of IBS patients increased Caco-2 permeability compared to AC mediators (P<0.05) via a down-regulation of tight junction gene expression. Blood vessels were significantly increased by 1.5 fold in the colonic mucosa of IBS patients compared to AC (P<0.01). PV1 expression was increased (P<0.01) while VEC expression was decreased in the colonic mucosa of IBS group compared to AC (P<0.05). IBS mucosal mediators increased HUVEC permeability compared to AC mediators. The HUVEC changes associated with IBS samples were mediated by a protease-activated receptor (PAR)2 dependent mechanism resulting in VEC down-regulation. Significant correlations emerged among permeability changes and intestinal, extra-intestinal symptoms and health-related quality of life reported by IBS patients.

Conclusion

Epithelial and vascular barriers are compromised in IBS and are likely involved in symptom development.

Disclosure

Nothing to disclose