Introduction

Aging exerts several effects on the brain and gastrointestinal (GI) tract, causing progressive deterioration of physiological function, higher occurrence of functional GI disorders and cognitive decline. The elderly population is particularly susceptible to malnutrition, dysphagia, constipation or fecal incontinence, and central neurodegeneration.¹ An age-related decline arises in gut function including neurons and glia of the enteric nervous system (ENS) and impairment of intestinal cholinergic neuromuscular response and is associated to defects on mucosal barrier and impaired innate immunity.^2,3

Aims & Methods

Aim: We aimed to assess the effect of Toll-like receptor 4 (TLR4) deficiency on ENS homeostasis during aging.
Methods: Confocal immunoreactivity of the neuronal proteins HuC/D and alpha-synuclein as well as the glial markers S100β and GFAP was determined in longitudinal-muscle-myenteric plexus whole-mounts preparations (LMMPs) of male young (aged 3±1 months) and middle adult (aged 12±1 months) C57/Bl6 (WT) and sex- and age-matched TLR4^-/- mice (N=16 animals/group). Gastrointestinal transit was measured by nonabsorbable-FITC-labeled dextran distribution. Changes in ileal contractility were recorded following: i) cumulative addition of carbachol (CCh; 0.1-100 μM); ii) electric field stimulation (EFS, 0-40 Hz); iii) 10 Hz-electric-field-stimulation in non-adrenergic, non-cholinergic (NANC) conditions (1 μM atropine + 1 μM guanethidine), with or without 0.1 μM 1400W (inhibitor of inducible nitric oxide synthase, iNOS), or 100 μM L-NAME (pan-NOS inhibitor).

Results

Aging determined dysmotility and a delayed gastrointestinal transit only in WT mice (p<0.01). A reduced cholinergic receptor mediated response (Emax=-43%; p<0.001) together with a defective neurotransmission (-45% at 10 Hz; p<0.001) was found in 12-months-old WT mice compared to young mice. In TLR4^-/- mice, aging determined increased EFS-mediated response (+40% at 10 Hz; p<0.05) with no changes in CCh-induced contraction. An age-related significant increase in NANC relaxation, sensitive to 1400W or L-NAME, was revealed in both 12-months-old WT and TLR4^-/- mice. A significant reduction of the total number of HuC/D⁺ neurons (-26%; p<0.01) associated to increased S100β (+25%; p<0.001), GFAP (+28%; p<0.05) and alpha-synuclein (+96%; p<0.01) immunoreactivity, was assessed in LMMPs of aged WT mice with no alterations in the myenteric neuroglial network of 12-months-old TLR4^-/- mice.

Conclusion

TLR4 signaling influences the course of aging in terms of small intestine dysmotility and altered myenteric neuro-glial plasticity. These findings uncover the intriguing role of TLR4 in modulating the GI systema affected by senescence that could be targeted for promoting healthy aging.

References

¹ Saffrey MJ. Age (Dordr). 2014;36:9603
² Broad J, et al. Gut. 2019;68:1210-1223
³ Bosco N, Noti M. Genes Immun. 2021;22:289-303.

Introduction

Multiple sclerosis (MS) is a chronic, immune-mediated demyelinating disease of the central nervous system (CNS) affecting young adults, with a female preponderance.¹ A large number of evidences indicate that the gut-brain axis is involved in the pathophysiology of neurodegenerative diseases, including MS. In addition to symptoms caused by CNS pathology, the majority of MS patients frequently exhibit functional gastrointestinal (GI) disorders, such as constipation, dysphagia, dyspepsia, fecal incontinence, and dysbiosis.² Novel findings in both MS patients and animal models propose the ENS as the first site of origin of MS, due to its interaction with microbial-derived factors and immune responses.^3,4

Aims & Methods

Aim: The aim of the present study, supported by a BINC-Genève grant, was to investigate the effect of cuprizone-mediated demyelination on the structural and functional integrity of the ENS.
Methods: Female C57/Bl6 (3±1 weeks old; N=18/group) mice were fed with standard diet (SHAM) or with standard diet supplemented with 0.25% (w/w) cuprizone for 4 weeks (CPZ). Animal health status was monitored by recording body weight daily. In SHAM and CPZ-treated mice changes in recognition memory and locomotor activity were evaluated using the novel object recognition, open field, beam walking tests. At the end of the behavioral tests, animals sacrificed by cervical dislocation and analyzed for changes in gut function. GI transit was assessed by measuring the distribution of nonabsorbable-FITC-labeled dextran throughout the GI tract. Changes in contractility were recorded in ileum segments following: i) 60 mM KCl; ii) cumulative addition of carbachol (CCh; 0.1-100 μM); iii) electric field stimulation (EFS, 0-40 Hz). The distribution of neuronal (HuC/D, ChAT) and glial (S100β, PLP1) markers was determined by immunohistochemistry and confocal microscopy in longitudinal-muscle-myenteric plexus whole-mount ileum preparations. Expression of myelin-related genes was analyzed by RT-qPCR in ileal tissue samples.

Results

CPZ administration led to weight loss (-20%) and caused a delayed GI transit (p<0.001), associated to deficits in recognition memory and locomotor activity. In vitro contractility studies showed reduced frequency and amplitude of contractions in CPZ mice (-10% and -35.3%, respectively; p<0.05). CPZ treatment determined changes in receptor- and not-receptor mediated excitatory responses (-28% of Emax to CCh and -33% of contraction to KCl, respectively; p<0.01) together with reduced EFS-induced contractions (-24.5% at 40 Hz; p<0.01). In the myenteric plexus of CPZ mice, we found marked alterations in glial cells distribution, accompanied by a significant reduction of the number of HuC/D⁺ neurons (-15%; p<0.01), and disrupted cholinergic network (-30% in ChAT immunoreactivity; p<0.01). Significant changes in myelin-related genes expression (MOG, MBP, PLP1) were found in ileal tissues of CPZ compared to SHAM mice.

Conclusion

Our findings show that cuprizone determines small intestine dysmotility and altered myenteric neuro-glial plasticity within the ENS of female mice. Further studies are warranted to assess the mechanisms that lead to the onset and spread of neurodegeneration within the gut, from the gut to the brain, and vice versa.

References

REFERENCES:
¹Cloake NC, et al. J Clin Med. 2018;7:342
²Levinthal DJ,et al. Mult Scler Int. 2013;2013:319201
³Wunsch M, et al. Acta Neuropathol. 2017;134:281-295
⁴Parodi B, Kerlero de Rosbo N. Front Immunol. 2021;12:718220

Introduction

Loop ileostomy has been reported to reduce the risk of leakage and reoperation in patients undergoing sphincter-preserving surgery. The structural and functional changes in the loop ileostomy may contribute to the development of ileus, such as decreased motility of smooth muscle and villous atrophy.

Aims & Methods

This study is to investigate the morphological, functional, and molecular changes of the distal limb after ileostomy and subsequent takedown.
Human ileum samples were obtained from patients who underwent diversion ileostomy after rectal cancer surgery and subsequently had ileostomy takedown. Samples were collected from the tips of the proximal and distal limbs. The whole layer of ileum was prepared for HE staining and the muscle layer which the mucosal layer was removed was prepared for motility measurement. The muscle strips (5x2 mm) were mounted to an isometric force transducer (Biopac Systems, Inc., Goleta, CA, USA) and suspended in 10 ml organ bath containing aerated (97% O₂ and 3% CO₂) and pre-warmed (36.5 ± 0.5°C) KRB solution. Amplitude (mN) and area under the curve (AUC) of contractions were measured and analyzed. To compare myogenic contraction and relaxation between the proximal and distal limbs of ileostomy, we administrated acetylcholine (ACh), potassium chloride (KCl) and sodium nitroprusside (SNP) in human ileal strips. Quantitative real-time polymerase chain reaction (qPCR) was performed for quantitative analysis of the expression of VAChT and NOS, cholinergic and nitrergic neuronal markers, and UCHL1 and MYH11, neuronal and smooth muscle cell marker, respectively.

Results

The height of the villi and the thickness of the mucosa, submucosa and muscle layer of the distal limb decreased significantly compared to those of the proximal limb. In the contractile responses to ACh and KCl, the amplitude and AUC of contractions in the distal limb were smaller than in the proximal limb in a dose-dependent manner. The relaxation response to the SNP in the distal limb was reduced compared to the proximal limb. Expressions of VAChT which is related with cholinergic neurotransmission, UCHL1 and MYH11 were not different in both proximal and distal limbs. However, expression of NOS1 which is related with nitrergic neurotransmission was increased significantly in the distal limb compared to the proximal limb. In addition, number of interstitial cells (ICC and PDGFRa⁺ cell) in muscle layer was not different in both proximal and distal limbs.

Conclusion

These results demonstrate that the distal limb which was not in use for a certain period of time after fecal diversion was morphologically atrophied and its motility was also impaired. Both myogenic contractile and relaxation responses were reduced in the distal limb of ileostomy although nitrergic neurons increased in the distal limb to compensate for the reduced relaxation response. These findings suggest that stimulating the distal limb can induce relaxation and may be a way to prevent ileus, which can occur after ileostomy takedown.

Introduction

Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RAs) have gained attention for their role in managing type 2 diabetes and obesity. These drugs help regulate blood sugar levels and promote satiety. This effect benefits weight management, as it supports better control over eating habits and can lead to significant weight loss in some patients. In addition, recent studies showed promising influences on reducing alcohol consumption.

Aims & Methods

This systematic review assesses the impact of GLP-1 RA treatment on alcohol consumption behaviors. Following PRISMA guidelines, this study is conducted through a comprehensive search in PubMed, EMBASE, Scopus, Cochrane, and ClinicalTrials.gov up to February 1, 2025. It included participants with occasional or excessive alcohol use, focusing on self-reported intake, alcohol-related diagnoses, relapse rates, and neuroimaging. Data extraction and risk-of-bias assessments were independently performed by reviewers using the CASP tool, with both qualitative and quantitative synthesis of outcomes.

Results

Thirteen studies are included in this study with a sample size of 5,246,188 participants. The GLP-1 RAs consisted of Semaglutide, Exenatide, Liraglutide, Dulaglutide, and Tirzepatide. The overall mean alcohol intake decreased significantly from 11.8 ± 1.0 to 4.3 ± 0.5 units per week (p < 0.001) ¹. At week 12, participants in the dulaglutide group consumed approximately 29% less alcohol than those in the placebo group (adjusted relative effect = 0.71, 95% CI 0.52–0.97, P = 0.04) ². In contrast, a randomized controlled trial (RCT) involving Exenatide showed no difference in alcohol consumption (in grams) between the treatment and placebo ³. Additionally, two observational studies reported significant reductions in Alcohol Use Disorders Identification Test (AUDIT) scores with Semaglutide (B = -5.1, SE = 1.3, p < 0.001) and Tirzepatide (B = -6.7, SE = 1.3, p < 0.001) ^4,5. An additional observational study demonstrated a notable decrease in AUDIT-Consumption compared to unexposed individuals (DiD: 0.09 points, 95% CI: 0.03–0.14, p = 0.0025) ⁶. The CASP assessments rated most studies as moderate to high quality.

Conclusion

GLP-1 receptor agonists appear to offer a promising, effective, and well-tolerated pharmacological approach for reducing alcohol consumption and preventing relapse in alcohol use disorder (AUD). Further large-scale randomized trials are required to confirm their efficacy and guide clinical practice.

References

1. O’Farrell M, Almohaileb FI, le Roux CW. Glucagon-like peptide-1 analogues reduce alcohol intake. Diabetes Obes Metab. 2025;27(3):1601-1604. doi:10.1111/DOM.16152
2. Probst L, Monnerat S, Vogt DR, et al. Effects of dulaglutide on alcohol consumption during smoking cessation. JCI Insight. 2023;8(22). doi:10.1172/JCI.INSIGHT.170419
3. Klausen MK, Jensen ME, Møller M, et al. Exenatide once weekly for alcohol use disorder investigated in a randomized, placebo-controlled clinical trial. JCI Insight. 2022;7(19). doi:10.1172/JCI.INSIGHT.159863
4. Quddos F, Hubshman Z, Tegge A, et al. Semaglutide and Tirzepatide reduce alcohol consumption in individuals with obesity. Scientific Reports 2023 13:1. 2023;13(1):1-12. doi:10.1038/s41598-023-48267-2
5. Richards J, Dorand MF, Royal K, Mnajjed L, Paszkowiak M, Simmons WK. Significant Decrease in Alcohol Use Disorder Symptoms Secondary to Semaglutide Therapy for Weight Loss: A Case Series. J Clin Psychiatry. 2023;85(1). doi:10.4088/JCP.23M15068
6. Farokhnia M, Tazare J, Pince CL, et al. Glucagon-like peptide-1 receptor agonists but not dipeptidyl peptidase-4 inhibitors reduce alcohol intake.

Disclosure

The authors declare no conflicts of interest regarding the publication of this abstract. All findings and conclusions are the authors' own and do not represent the views of any funding organizations or institutions.

Introduction

Abdominal surgery frequently results in postoperative ileus (POI), a neuroinflammation-based disorder of the gastrointestinal tract, characterized by motility disturbances leading to prolonged hospital stay and increased health care costs. The underlying neuroinflammation involves activation of resident macrophages and monocyte-derived macrophages (MDM) infiltration into the intestine's muscularis externa (ME). Immune checkpoint proteins, including PD-1 and its ligands PD-L1 and PD-L2, play a prominent role in cancer immunology, while less is known about their role in non-oncological inflammatory diseases.

Aims & Methods

The aim of this study was to investigate the role of PD-1 signaling in POI development. POI was induced by a surgical intestinal manipulation in wildtype (wt), PD-1^-/-, PD-L1^-/- and PD-L2^-/- mice. We performed immunohistochemistry and flow cytometry to identify the cellular sources of PD-1 and PD-L1 and used a blood cell transfer model to determine the role of a leukocyte-restricted PD-1 deficiency on immune cell infiltration. By qPCR, bulk 3´mRNA sequencing and use of the SMART-Seq2 technology in sorted CX3CR1^GFP/+ resident and monocyte-derived macrophages, we analysed transcriptional and functional differences between wt and PD-1^-/- macrophage populations. Furthermore, we quantified neuronal cell loss, in vitro and in vivo macrophage phagocytosis, GI transit measurements and metabolic activity by Seahorse XF Real-Time ATP rate assays to further characterize functional changes linked to PD-1 deficiency.

Results

PD-1, PD-L1 and PD-L2 mRNA levels were induced in the postoperative ME upon intestinal manipulation. PD-1^-/- and PD-L1^-/-, but not PD-L2^-/- mice, were protected from POI. PD-1^-/- mice showed a 50% reduction of MDM infiltration and reduced inflammation-mediated neuronal loss. A cell transfer experiment confirmed a 60% reduction of postoperative ME infiltration of PD-1 deficient leukocytes compared to wt leukocytes. Ly6C^-CX3CR1⁺ resident macrophages and Ly6C⁺CX3CR1⁺ MDM were identified as the primary cellular source of PD-1 in POI. PD-1 deficient Ly6C⁺CX3CR1⁺ MDM showed reduced in vivo phagocytosis, which was confirmed in bone-marrow derived macrophage cultures. Gene ontology analysis of postoperative ME samples of PD-1 and wt mice revealed lower enrichment levels of genes regulating metabolic respiratory chain processes, oxidative stress, cell death and immune functions. Moreover, GSEA analyses of sorted PD-1^-/-CX3CR1⁺Ly6C⁺ MDM showed reduced enrichment of genes associated with various immune functions, host defense and regulation of immune and neuronal cell death as well as an alteration of metabolic genes in POI. Seahorse XF Real-Time ATP rate measurement showed no difference between naïve monocytes from wt and PD-1^-/- mice. However, PD-1^-/- monocytes identified an increased oxidative chain reaction-dependent ATP generation during LPS stimulation.

Conclusion

Our data provide new evidence on the role of PD-1 signaling in MDM during postoperative intestinal neuroinflammation following abdominal surgery. PD-1 deficiency prevents POI, results in a metabolic switch and reduces inflammation-mediated neuronal loss as well as infiltration capacity and phagocytosis of MDM. Interaction in PD-1 signaling might be a potential target in prevention of POI.

Introduction

Patients with intestinal failure (IF) have abnormalities of intestinal anatomy, secretion, and/or motility, and physiological protective mechanisms regulating small intestinal bacterial counts are impaired, which can lead to small intestinal bacterial overgrowth. There are five key mechanisms that drive intestinal failure, of which, short bowel syndrome (SBS) following surgical resection is the most common. Less frequent mechanisms include enterocutaneous fistula, dysmotility, obstruction and malabsorption. Small intestinal bacterial overgrowth (SIBO) and catheter related blood stream infections (CRBSI) are two of the most common complications with a direct impact on morbidity and mortality. Parenteral nutrition (PN) use in intestinal failure has also been proposed as an independent risk factor for development of SIBO. However, the reported prevalence of SIBO in patients with IF is variable. We thus conducted a systematic review and meta-analysis aimed to determine the prevalence of SIBO in patients with IF and to identify the risk factors that predict SIBO in this cohort.

Aims & Methods

MEDLINE (PubMed) and Embase electronic databases were searched from inception to April 2023 for studies that reported the prevalence of SIBO in IF. The prevalence rates, odds ratio (OR) and 95% confidence intervals of SIBO in IF were calculated using DerSimonian and Laird random effects model, and further subgroup analysis stratified according to mode of SIBO diagnosis and short-bowel syndrome cause of IF were conducted. This study was registered with PROSPERO (CRD42023414010).

Results

Six prevalence studies reporting on 313 patients with IF were included in this systematic review and meta-analysis. Overall, the prevalence of SIBO in IF was 55.2% (95% CI: 41.5-68.2), with considerable heterogeneity in this analysis (I²=79.2, p=0.0001), with slightly increased SIBO prevalence in IF patients on parenteral nutrition (61.1% 95% CI 31.6-84.3). There was no difference in CRBSI in SIBO positive (45.5%, 95% CI: 28.1-63.6) as compared to SIBO negative IF patients (45.7%, 95%CI 16.7-76.6). Utilizing duodenal aspirate and culture SIBO prevalence in patients with IF was significantly higher as compared to that with glucose breath test (OR 2.59, 95% CI 1.2-5.8, p=0.03), with moderate heterogeneity noted in this analysis (I²=53.9, p=0.054). There was no difference in SIBO prevalence in patients with IF due to SBS (49.1%, 95% CI 42.7-55.4) as compared to IF due to other causes (53.5%, 95%CI 37.7-68.8).

Conclusion

This systematic review and meta-analysis suggests a link between SIBO and IF, with higher SIBO prevalence in patients with IF diagnosed utilizing small bowel aspirate and culture. Parenteral nutrition appeared to be risk factor for SIBO in IF. Moreover, there was no like between SIBO and CRBSI in patients with IF. However, the results need to be interpreted with caution, due to the low sensitivity and specificity of the SIBO diagnostic tests, lack of case control studies and clinical heterogeneity seen in the prevalence studies. Further prospective studies are required to further assess the link between SIBO and IF and explore the risk factors for SIBO in IF.