A Review on Inflammatory Bowel Diseases: Recent Molecular Pathophysiology Advances

Efficacy of Dietary Supplementation in the Relief of Inflammatory Bowel Disease: A Systematic Review of Animal Studies

CONTEXT

Supplementation with dietary components is a promising approach for the treatment of inflammatory bowel disease (IBD).

OBJECTIVE

The aim was to examine the effects of dietary supplements on experimental animal models of IBD.

DATA SOURCES

Articles were selected from 2016 to 2021 and from specific databases (PubMed, Embase, and Scopus).

DATA EXTRACTION

Forty-nine studies were analyzed.

DATA ANALYSIS

Of the 49 studies, 8 investigated supplementation with oils/polyunsaturated fatty acids, 5 with flavones, 5 with prebiotics and probiotics, 6 with amino acids, 4 with fruits, 4 with vegetables, 2 with minerals, 2 with vitamins, 3 with plants, 2 with polyphenols, and 8 from various sources. Polyunsaturated fatty acids, flavones, prebiotics, and probiotics are among the most extensively studied compounds. Protection is associated with reducing inflammation and oxidative stress, protecting the epithelial barrier and altering the microbiota; however, more rigorous protocols are needed to definitively confirm their protective effects and enable translational research. Fruits, vegetables, plant compounds, minerals, vitamins, and polyphenols, on the other hand, should be studied further and deserve more attention in research.

CONCLUSION

The results included here support further research into the beneficial effects of supplementation in IBD. Some studies are more advanced and have presented more elaborate protocols, while others still require an increase in knowledge. The identification of dietary supplements that can improve the course of IBD could have an important and lasting impact on the treatment of IBD.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42022295260.

The Impact of Immunomodulatory Components Used in Clinical Nutrition-A Narrative Review

BACKGROUND

Malnutrition is a clinical condition that leads to unfavourable changes in health. It affects 35-55% of hospitalized patients, and in the case of cancer, this prevalence rises to 40-90% of patients. Screening nutritional status is essential for preventing undernutrition, which is crucial as its treatment. Undernutrition in patients after severe injuries significantly increases catabolic changes. Cytokines and hormones, such as epinephrine, glucagon, and cortisol, are released, which can increase energy expenditure by 50%. Properly conducted nutritional treatment aims to maintain or improve the nutritional status of patients whose nutrition with a natural diet is insufficient, moreover, in some cases, treatment of the underlying disease.

METHODS

This study is a narrative review focused on immunonutrition. The search for source articles, mainly from the last 10 years, was conducted in the PubMed and Google Schoolar databases, as well as in printed books. The key words used were "malnutrition", "inflammation", "clinical nutrition", "immunomodulatory components", "nutritional status assessment", "enteral nutrition", "parenteral nutrition", and their combinations.

RESULTS

Providing substances such as omega-3 fatty acids, glutamine, arginine, nucleotides, antioxidants, and prebiotic fiber has a beneficial impact on immunological and anti-inflammatory pathways. The above-mentioned ingredients may inhibit the secretion of pro-inflammatory cytokines, activate anti-inflammatory cytokines, stimulate immune cells, and have a beneficial effect in allergic diseases, respiratory infections, or wound healing.

CONSLUSION

Immunonutrition can be administrated via oral, enteral, and parenteral routes. It is crucial to highlight the importance of proper nutritional status in patients. The relationship between inflammation and malnutrition creates a vicious cycle, where one negatively affects the other due to increased metabolic demand, loss of appetite, weakened immune system, and gut dysbiosis.

Novel Insights into the Pathogenesis of Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBDs), encompassing Crohn's disease and ulcerative colitis, are complex chronic disorders characterized by an intricate interplay between genetic predisposition, immune dysregulation, gut microbiota alterations, and environmental exposures. This review aims to synthesize recent advances in IBD pathogenesis, exploring key mechanisms and potential avenues for prevention and personalized therapy. A comprehensive literature search was conducted across major bibliographic databases, selecting the most recent and impactful studies on IBD pathogenesis. The review integrates findings from multi-omics analyses, single-cell transcriptomics, and longitudinal cohort studies, focusing on immune regulation, gut microbiota dynamics, and environmental factors influencing disease onset and progression. Immune dysregulation, including macrophage polarization (M1 vs. M2) and Th17 activation, emerges as a cornerstone of IBD pathogenesis. Dysbiosis, as a result of reduced alpha and beta diversity and overgrowth of harmful taxa, is one of the main contributing factors in causing inflammation in IBD. Environmental factors, including air and water pollutants, maternal smoking, and antibiotic exposure during pregnancy and infancy, significantly modulate IBD risk through epigenetic and microbiota-mediated mechanisms. While recent advances have supported the development of new therapeutic strategies, deeply understanding the complex dynamics of IBD pathogenesis remains challenging. Future efforts should aim to reduce the burden of disease with precise, personalized treatments and lower the incidence of IBD through early-life prevention and targeted interventions addressing modifiable risk factors.

Saloplastics based on protein-peptides complexes immobilizing organic molecules in gastrointestinal drug delivery for ulcerative colitis treatment

Ulcerative colitis (UC) stands as a chronic inflammatory intestinal disease. This study aimed to explore a sustained-release strategy to alleviate DSS-induced colitis in mice using polyelectrolyte complexes (PECs) encapsulating an alkaloid, isoliensinine (ISO). The drug delivery platform, termed "Saloplastics (SAL)", was prepared by fabrication of PECs through the solid-liquid phase separation of sodium caseinate (SC) and ε-polylysine (EPL), followed by centrifugation to yield compact structures. Coarse-grained molecular dynamics simulations demonstrated that SAL had a nanorod-like structure formation between EPL and SC, which implied that the self-assembly of SAL is driven by hydrophobic aggregation and strong electrostatic attractions. A comprehensive evaluation of SAL was conducted, including characterizations of its physicochemical and biological properties. The results showed SAL had thermal plasticization properties and excellent swelling capacity as well as susceptibility to hydrolysis by pH and proteinase in simulated gastric fluid. Moreover, SAL displayed a porous morphology with high surface area for immobilizing organic molecules. ISO@SAL, formulated by ISO encapsulated in SAL, not only demonstrated high potency in alleviating DSS-induced colitis in mice, but also increased the dosing intervals from one day to three days. In conclusion, SAL is a biocompatible sustained-release oral drug delivery platform for gastrointestinal applications.

Iron regulatory protein 2 contributes to antimicrobial immunity by preserving lysosomal function in macrophages

Colorectal cancer and Crohn's disease patients develop pyogenic liver abscesses due to failures of immune cells to fight off bacterial infections. Here, we show that mice lacking iron regulatory protein 2 (Irp2), globally (Irp2-/-) or myeloid cell lineage (Lysozyme 2 promoter-driven, LysM)-specifically (Irp2ΔLysM), are highly susceptible to liver abscesses when the intestinal tissue was injured with dextran sodium sulfate treatment. Further studies demonstrated that Irp2 is required for lysosomal acidification and biogenesis, both of which are crucial for bacterial clearance. In Irp2-deficient liver tissue or macrophages, the nuclear location of transcription factor EB (Tfeb) was remarkably reduced, leading to the downregulation of Tfeb target genes that encode critical components for lysosomal biogenesis. Tfeb mislocalization was reversed by hypoxia-inducible factor 2 inhibitor PT2385 and, independently, through inhibition of lactic acid production. These experimental findings were confirmed clinically in patients with Crohn's disease and through bioinformatic searches in databases from Crohn's disease or ulcerative colitis biopsies showing loss of IRP2 and transcription factor EB (TFEB)-dependent lysosomal gene expression. Overall, our study highlights a mechanism whereby Irp2 supports nuclear translocation of Tfeb and lysosomal function, preserving macrophage antimicrobial activity and protecting the liver against invading bacteria during intestinal inflammation.

Therapeutic Applications of Aggregatibacter actinomycetemcomitans Leukotoxin

Aggregatibacter actinomycetemcomitans is a Gram-negative oral bacterium that has been primarily studied for its role in causing periodontal disease. The bacterium has also been implicated in several systemic diseases such as endocarditis and soft tissue abscesses. Leukotoxin (LtxA) is perhaps the best studied protein virulence factor from A. actinomycetemcomitans. The protein can rapidly destroy white blood cells (WBCs), helping the bacterium to subvert the host immune system. The functional receptor for LtxA is lymphocyte function associated antigen-1 (LFA-1), which is expressed exclusively on the surfaces of WBCs. Bacterial expression and secretion of the protein are highly regulated and controlled by a number of genetic and environmental factors. The mechanism of LtxA action on WBCs varies depending on the type of cell that is being killed, and the protein has been shown to activate numerous cell death pathways in susceptible cells. In addition to serving as an important virulence factor for the bacterium, because of its exquisite specificity and rapid activity, LtxA is also being investigated as a therapeutic agent that may be used to treat diseases such as hematological malignancies and autoimmune/inflammatory diseases. It is our hope that this review will inspire an increased intensity of research related to LtxA and its effect on Aggressive Periodontitis, the disease that led to its initial discovery.

Psilocybin and Eugenol Reduce Inflammation in Human 3D EpiIntestinal Tissue

Inflammation plays a pivotal role in the development and progression of inflammatory bowel disease (IBD), by contributing to tissue damage and exacerbating the immune response. The investigation of serotonin receptor 2A (5-HT2A) ligands and transient receptor potential (TRP) channel ligands is of significant interest due to their potential to modulate key inflammatory pathways, mitigate the pathological effects of inflammation, and offer new avenues for therapeutic interventions in IBD. This study investigates the anti-inflammatory effects of 5-HT2A ligands, including psilocybin, 4-AcO-DMT, and ketanserin, in combination with TRP channel ligands, including capsaicin, curcumin, and eugenol, on the inflammatory response induced by tumor necrosis factor (TNF)-α and interferon (IFN)-γ in human 3D EpiIntestinal tissue. Enzyme-linked immunosorbent assay was used to assess the expression of pro-inflammatory markers TNF-α, IFN-γ, IL-6, IL-8, MCP-1, and GM-CSF. Our results show that psilocybin, 4-AcO-DMT, and eugenol significantly reduce TNF-α and IFN-γ levels, while capsaicin and curcumin decrease these markers to a lesser extent. Psilocybin effectively lowers IL-6 and IL-8 levels, but curcumin, capsaicin, and 4-AcO-DMT have limited effects on these markers. In addition, psilocybin can significantly decrease MCP-1 and GM-CSF levels. While ketanserin lowers IL-6 and GM-CSF levels, there are no effects seen on TNF-α, IFN-γ, IL-8, or MCP-1. Although synergistic effects between 5-HT2A and TRP channel ligands are minimal in this study, the results provide further evidence of the anti-inflammatory effects of psilocybin and eugenol. Further research is needed to understand the mechanisms of action and the feasibility of using these compounds as anti-inflammatory therapies for conditions like IBD.

Evaluation of Disease Activity in Inflammatory Bowel Disease: Diagnostic Tools in the Assessment of Histological Healing

Inflammatory bowel disease (IBD) comprises two types of chronic intestinal disorders: Crohn's disease and ulcerative colitis. In long-standing ulcerative colitis disease activity, histological persistent inflammation has been linked to an increased risk of relapse, and long-term corticosteroid use, even when endoscopic remission is reached. In Crohn's disease, the discontinuous nature of lesions and transmural inflammation have limited the standardized histological assessment. The current evidence from research proposes that besides clinical and endoscopic healing, the achievement of histological healing constitutes an endpoint to assess disease activity and remission in IBD patients concerning better long-term disease outcomes. Histological alterations may persist even in the absence of endoscopic lesions. For these reasons, new advanced techniques promise to revolutionize the field of IBD by improving the endoscopic and histologic assessment, disease characterization, and ultimately patient care, with an established role in daily practice for objective assessment of lesions. This review outlines the importance of including microscopic evaluation in IBD, highlighting the clinical benefits of a deep state of disease remission using validated diagnostic methods and scoring systems for daily clinical practice.