Treatment of inflammatory bowel disease from the immunological perspective

Maslinic Acid Ameliorates DSS-Induced Experimental Colitis by Suppressing Th Cell-Mediated Inflammation via AICD Induction

Ulcerative colitis (UC) is a nonspecific chronic inflammatory disease that occurs in the gastrointestinal tract and is characterized by the breakdown of mucosal immunity. T helper (Th) cells paradigm disequilibrium is a critical for pathogenesis. Maslinic acid (MA), a naturally occurring pentacyclic triterpene isolated from olive pomace and Fructus crataegi, has a variety of applications in both medicine and food. This study investigated the molecular mechanism of the anti-inflammatory potential of MA in a colitis model and activated Th cells. A dextran sulfate sodium-induced experimental colitis model was established. Clinical symptoms were evaluated, and biological samples were collected to examine intestinal mucosal function, inflammation levels, and Th cell-mediated immune responses. The mechanism of the activation-induced cell death (AICD) effect regulated by MA was investigated in the anti-CD3ε/CD28-stimulated Th cell activation model using molecular biotechnology and transcriptome analysis. Key results:MA treatment protected intestinal mucosa, which manifested as reduced inflammatory cytokines, Th cell infiltration, and subset differentiation. Additionally, it was found to suppress Th cell proliferation and differentiation of subsets, regulate cell cycle distribution, and promote AICD by regulating the mitochondria-mediated intrinsic pathway in vitro. JAK-STAT and FcεRI pathways were probable essential pathways, and MAF might be a crucial potential targeting molecule in activated Th cells with MA treatment. This finding demonstrated that MA induced remission of the colitis-related inflammation, which may depend on the resolution of acute inflammation by reducing Th cell-mediated inflammation via AICD induction, emphasizing its promising potential in the treatment of UC.

The Simultaneous Deletion of pH-Sensing Receptors GPR4 and OGR1 (GPR68) Ameliorates Colitis with Additive Effects on Multiple Parameters of Inflammation

G protein-coupled receptors (GPRs), including pro-inflammatory GPR4 and ovarian cancer GPR1 (OGR1/GPR68), are involved in the pH sensing of the extracellular space and have been implicated in inflammatory bowel disease (IBD). Previous data show that a loss of GPR4 or OGR1 independently is associated with reduced intestinal inflammation in mouse models of experimental colitis. In the present manuscript, we investigated the impact of the simultaneous loss of GPR4 and OGR1 in animal models of IBD. To study the effects of combined loss of Gpr4 Ogr1 in IBD we used the well-established acute dextran sodium sulfate (DSS) and spontaneous Il10-/- murine colitis models. Disease severity was assessed using multiple clinical scores (e.g., body weight loss, disease activity score, murine endoscopic index of colitis severity (MEICS) and histological analyses). Real-time quantitative polymerase chain reaction (qPCR), Western blot, and flow cytometry were used to investigate changes in pro-inflammatory cytokines expression and immune cells infiltration. We found that a combined loss of GPR4 and OGR1 significantly reduces colon inflammation in IBD relative to single deficiencies as evidenced by reduced body weight loss, disease score, CD4/CD8 ratio, and Il1β, Il6, and Tnf in the colon. Similarly, in the II10 deficiency model, the inflammation was significantly ameliorated upon the simultaneous deletion of GPR4 and OGR1, evidenced by a reduction in the MEICS score, colon length, Tnf and Il1β measurements, and a decrease in the number of macrophages in the colon, as compared to single deletions. Importantly, hydroxyproline levels were decreased close to baseline in Il10-/- × Gpr4-/- × Ogr1-/- mice. Our findings demonstrate that the simultaneous loss of GRP4 and OGR1 functions exerts an additive effect on multiple parameters associated with colonic inflammation. These results further reinforce the hypothesis that chronic inflammatory acidosis is a driver of fibrosis and is dependent on GPR4 and OGR1 signaling. The inhibition of both GPR4 and OGR1 by pH-sensing receptor modulators may constitute as a potential therapeutic option for IBD, as both pH-sensing receptors appear to sustain inflammation by acting on complementary pro-inflammatory pathways.

Ulcerative colitis: molecular insights and intervention therapy

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by abdominal pain, diarrhea, rectal bleeding, and weight loss. The pathogenesis and treatment of UC remain key areas of research interest. Various factors, including genetic predisposition, immune dysregulation, and alterations in the gut microbiota, are believed to contribute to the pathogenesis of UC. Current treatments for UC include 5-aminosalicylic acids, corticosteroids, immunosuppressants, and biologics. However, study reported that the one-year clinical remission rate is only around 40%. It is necessary to prompt the exploration of new treatment modalities. Biologic therapies, such as anti-TNF-α monoclonal antibody and JAK inhibitor, primarily consist of small molecules targeting specific pathways, effectively inducing and maintaining remission. Given the significant role of the gut microbiota, research into intestinal microecologics, such as probiotics and prebiotics, and fecal microbiota transplantation (FMT) shows promising potential in UC treatment. Additionally, medicinal herbs, such as chili pepper and turmeric, used in complementary therapy have shown promising results in UC management. This article reviews recent findings on the mechanisms of UC, including genetic susceptibility, immune cell dynamics and cytokine regulation, and gut microbiota alterations. It also discusses current applications of biologic therapy, herbal therapy, microecologics, and FMT, along with their prospects and challenges.

Cytokine Profile in Predicting the Effectiveness of Advanced Therapy for Ulcerative Colitis: A Narrative Review

Cytokine-targeted therapies have shown efficacy in treating patients with ulcerative colitis (UC), but responses to these advanced therapies can vary. This variability may be due to differences in cytokine profiles among patients with UC. While the etiology of UC is not fully understood, abnormalities of the cytokine profiles are deeply involved in its pathophysiology. Therefore, an approach focused on the cytokine profile of individual patients with UC is ideal. Recent studies have demonstrated that molecular analysis of cytokine profiles in UC can predict response to each advanced therapy. This narrative review summarizes the molecules involved in the efficacy of various advanced therapies for UC. Understanding these associations may be helpful in selecting optimal therapeutic agents.

Role of pH-sensing receptors in colitis

Low pH in the gut is associated with severe inflammation, fibrosis, and colorectal cancer (CRC) and is a hallmark of active inflammatory bowel disease (IBD). Subsequently, pH-sensing mechanisms are of interest for the understanding of IBD pathophysiology. Tissue hypoxia and acidosis-two contributing factors to disease pathophysiology-are linked to IBD, and understanding their interplay is highly relevant for the development of new therapeutic options. One member of the proton-sensing G protein-coupled receptor (GPCR) family, GPR65 (T-cell death-associated gene 8, TDAG8), was identified as a susceptibility gene for IBD in a large genome-wide association study. In response to acidic extracellular pH, GPR65 induces an anti-inflammatory response, whereas the two other proton-sensing receptors, GPR4 and GPR68 (ovarian cancer G protein-coupled receptor 1, OGR1), mediate pro-inflammatory responses. Here, we review the current knowledge on the role of these proton-sensing receptors in IBD and IBD-associated fibrosis and cancer, as well as colitis-associated cancer (CAC). We also describe emerging small molecule modulators of these receptors as therapeutic opportunities for the treatment of IBD.

Gut-brain axis interacts with immunomodulation in inflammatory bowel disease

The brain and the gastrointestinal (GI) tract are important sensory organs in the body and the two-way interaction that exists between them regulates key physiological and homeostatic functions. A growing body of research suggests that this bidirectional communication influences the development and progression of functional GI disorders and plays an important role in the treatment of central nervous system (CNS) disorders. Inflammatory bowel disease (IBD) is a classic intestinal disorder with a high prevalence but still unclear pathogenesis that has been widely discussed in recent years. However, in the studies available to date, we find that many authors have chosen to discuss the influence of the brain on intestinal disorders from the top down, starting with physical and psychological disorders. Coming very naturally, based on these substantial research evidence, we focus on exploring the links between bidirectional communication in the gut-brain axis and IBD, and highlight the role of the gut microbiota, vagus nerve (VN), receptors and immune cells involved in regulating IBD through the gut-brain axis in this review.

Cutaneous manifestations of inflammatory bowel disease: basic characteristics, therapy, and potential pathophysiological associations

Inflammatory bowel disease (IBD) is a chronic inflammatory disease typically involving the gastrointestinal tract but not limited to it. IBD can be subdivided into Crohn's disease (CD) and ulcerative colitis (UC). Extraintestinal manifestations (EIMs) are observed in up to 47% of patients with IBD, with the most frequent reports of cutaneous manifestations. Among these, pyoderma gangrenosum (PG) and erythema nodosum (EN) are the two most common skin manifestations in IBD, and both are immune-related inflammatory skin diseases. The presence of cutaneous EIMs may either be concordant with intestinal disease activity or have an independent course. Despite some progress in research on EIMs, for instance, ectopic expression of gut-specific mucosal address cell adhesion molecule-1 (MAdCAM-1) and chemokine CCL25 on the vascular endothelium of the portal tract have been demonstrated in IBD-related primary sclerosing cholangitis (PSC), little is understood about the potential pathophysiological associations between IBD and cutaneous EIMs. Whether cutaneous EIMs are inflammatory events with a commonly shared genetic background or environmental risk factors with IBD but independent of IBD or are the result of an extraintestinal extension of intestinal inflammation, remains unclear. The review aims to provide an overview of the two most representative cutaneous manifestations of IBD, describe IBD's epidemiology, clinical characteristics, and histology, and discuss the immunopathophysiology and existing treatment strategies with biologic agents, with a focus on the potential pathophysiological associations between IBD and cutaneous EIMs.

OGR1 (GPR68) and TDAG8 (GPR65) Have Antagonistic Effects in Models of Colonic Inflammation

G-protein-coupled receptors (GPRs), including pro-inflammatory ovarian cancer GPR1 (OGR1/GPR68) and anti-inflammatory T cell death-associated gene 8 (TDAG8/GPR65), are involved in pH sensing and linked to inflammatory bowel disease (IBD). OGR1 and TDAG8 show opposite effects. To determine which effect is predominant or physiologically more relevant, we deleted both receptors in models of intestinal inflammation. Combined Ogr1 and Tdag8 deficiency was assessed in spontaneous and acute murine colitis models. Disease severity was assessed using clinical scores. Colon samples were analyzed using quantitative polymerase chain reaction (qPCR) and flow cytometry (FACS). In acute colitis, Ogr1-deficient mice showed significantly decreased clinical scores compared with wildtype (WT) mice, while Tdag8-deficient mice and double knockout (KO) mice presented similar scores to WT. In Il-10-spontaneous colitis, Ogr1-deficient mice presented significantly decreased, and Tdag8-deficient mice had increased inflammation. In the Il10-/- × Ogr1-/- × Tdag8-/- triple KO mice, inflammation was significantly decreased compared with Tdag8-/-. Absence of Ogr1 reduced pro-inflammatory cytokines in Tdag8-deficient mice. Tdag8-/- had significantly more IFNγ+ T-lymphocytes and IL-23 T-helper cells in the colon compared with WT. The absence of OGR1 significantly alleviates the intestinal damage mediated by the lack of functional TDAG8. Both OGR1 and TDAG8 represent potential new targets for therapeutic intervention.

Yiyi Fuzi Baijiang Powder Alleviates Dextran Sulfate Sodium-Induced Ulcerative Colitis in Rats via Inhibiting the TLR4/NF-κB/NLRP3 Inflammasome Signaling Pathway to Repair the Intestinal Epithelial Barrier, and Modulating Intestinal Microbiota

Ulcerative colitis (UC) is a chronic non-specific inflammatory disease of the intestine, which is prone to recurrence and difficult to cure. Yiyi Fuzi Baijiang powder (YFBP), as a classic Chinese herbal formula, is commonly used in the clinical treatment of UC. However, its potential mechanism remains unclear. In this study, we investigated the mechanism by which YFBP exerts a therapeutic effect against UC. Firstly, we used network pharmacology to screen the active ingredients and potential targets of YFBP and constructed a "drug-ingredient-target" network. Based on bioinformatics, we searched for differentially expressed genes (DEGs) associated with UC and obtained common targets. The core targets of YFBP in the treatment of UC were identified using a protein-protein interaction (PPI) network, and molecular docking techniques were used to evaluate the binding energies of the core targets and corresponding ingredients. Enrichment analysis by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed that YFBP exerted therapeutic effects by regulating multiple inflammatory pathways including TLR4, NF-κB, and TNF. Secondly, an experimental study was carried out in vivo for verification. Our results demonstrated that YFBP could effectively improve the symptoms and intestinal pathological of UC rats. Further study showed that YFBP could significantly downregulate the expressions of TLR4 and p-NF-κB p65 in UC rats, inhibit the activation of NLRP3 inflammasome, reduce the levels of IL-1β and TNF-α, and then upregulate the expressions of tight junction proteins in intestinal epithelial cells. In addition, YFBP could improve the intestinal microbial community. In conclusion, our study revealed that YFBP had a good therapeutic effect on UC, and its mechanism might be related to the inhibition of the TLR4/NF-κB/NLRP3 inflammasome signaling pathway to repair intestinal epithelial barrier and the modulation of intestinal microbiota.

Targeting pathophysiological changes using biomaterials-based drug delivery systems: A key to managing inflammatory bowel disease

Inflammatory bowel disease (IBD) is a gastrointestinal disorder, affecting about several million people worldwide. Current treatments fail to adequately control some clinical symptoms in IBD patients, which can adversely impact the patient's quality of life. Hence, the development of new treatments for IBD is needed. Due to their unique properties such as biocompatibility and sustained release of a drug, biomaterials-based drug delivery systems can be regarded as promising candidates for IBD treatment. It is noteworthy that considering the pathophysiological changes occurred in the gastrointestinal tract of IBD patients, especially changes in pH, surface charge, the concentration of reactive oxygen species, and the expression of some biomolecules at the inflamed colon, can help in the rational design of biomaterials-based drug delivery systems for efficient management of IBD. Here, we discuss about targeting these pathophysiological changes using biomaterials-based drug delivery systems, which can provide important clues to establish a strategic roadmap for future studies.

New progress in research of Th17 cells and related cytokines in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic non-specific intestinal inflammatory disease. IBD is an immune disease, and there is no cure for it at present. Intestinal immunity is the research focus of IBD. Focusing on Th17 cells and related cytokines, this article reviews the updated research on IBD, including its etiology, its relationship with adaptive immunity, and its relationship with Th17 cells. We also introduce Th17 cells and related cytokines, and their research in IBD. Finally, we point out the future research direction of Th17 cells in IBD.

The influence of cytokines on the complex pathology of ulcerative colitis

Ulcerative colitis (UC) specifically affects the colon and rectum through multifactorial mechanisms associated with genetic alterations, environmental factors, microbiota, and mucosal immune dysregulation. In patients with corticosteroid-refractory UC, current therapies primarily employ antibodies against tumor necrosis factor-α, α4β7 integrin, and interleukin (IL)-12/23 p40; and a small-molecule Janus kinase inhibitor. Despite these revolutionary molecular targeting therapies introduced during the last two decades, 30%-55% of patients fail to respond such molecular targeting agents in the induction phase, requiring changes in treatment. Here we review basic and clinical research aimed to address this problem, focusing on the pathogenic effects of cytokines produced by innate and adaptive immune cells. For example, IL-1β, IL-6, tumor necrosis factor-α, T helper (Th) 1-, Th2-, and Th17-associated cytokines are expressed at relatively higher levels in the intestinal tissues of patients with UC. However, their expression levels depend on disease stage and patient characteristics. The complex pathology of UC may induce differences in responses to therapy. The findings of such studies strongly support the argument that future targeted therapies must focus on differences in cytokine levels associated with the stages of UC as well as on the distinct cytokine expression profiles of individual patients.