An apPEAling new therapeutic for ulcerative colitis?

Toll-like receptors in inflammatory bowel disease: A review of the role of phytochemicals

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic inflammation within the gastrointestinal tract with a remarkable impact on patients' quality of life. Toll-like receptors (TLR), as a key contributor of immune system in inflammation, has a critical role in the pathogenesis of IBD and thus, can be a suitable target of therapeutic agents. Medicinal plants have long been considered as a source of bioactive agents for different diseases, including IBD.

PURPOSE

This review discusses current state of the art on the role of plant-derived compounds for the management of IBD with a focus on TLRs.

METHODS

Electronic database including PubMed, Web of Science, and Scopus were searched up to January 2023 and all studies in which anticolitis effects of a phytochemical was assessed via modulation of TLRs were considered.

RESULTS

Different categories of phytochemicals, including flavonoids, lignans, alkaloids, terpenes, saccharides, and saponins have demonstrated modulatory effects on TLR in different animal and cell models of bowel inflammation. Flavonoids were the most studied phytochemicals amongst others. Also, TLR4 was the most important type of TLRs which were modulated by phytochemicals. Other mechanisms such as inhibition of pro-inflammatory cytokines, nuclear factor-κB pathway, nitric oxide synthesis pathway, cyclooxygenase-2, lipid peroxidation, as well as induction of endogenous antioxidant defense mechanisms were also reported for phytochemicals in various IBD models.

CONCLUSION

Taken together, a growing body of pre-clinical evidence support the efficacy of herbal compounds for the treatment of IBD via modulation of TLRs. Future clinical studies are recommended to assess the safety and efficacy of these compounds in human.

Hypoxia and Intestinal Inflammation: Common Molecular Mechanisms and Signaling Pathways

The gastrointestinal tract (GI) has a unique oxygenation profile. It should be noted that the state of hypoxia can be characteristic of both normal and pathological conditions. Hypoxia-inducible factors (HIF) play a key role in mediating the response to hypoxia, and they are tightly regulated by a group of enzymes called HIF prolyl hydroxylases (PHD). In this review, we discuss the involvement of inflammation hypoxia and signaling pathways in the pathogenesis of inflammatory bowel disease (IBD) and elaborate in detail on the role of HIF in multiple immune reactions during intestinal inflammation. We emphasize the critical influence of tissue microenvironment and highlight the existence of overlapping functions and immune responses mediated by the same molecular mechanisms. Finally, we also provide an update on the development of corresponding therapeutic approaches that would be useful for treatment or prophylaxis of inflammatory bowel disease.

Sophorolipids produced by Yarrowia lipolytica grown on Moringa oleifera oil cake protect against acetic acid-induced colitis in rats: impact on TLR-4/p-JNK/NFκB-p65 pathway

OBJECTIVES

Toll-like receptor-4 (TLR-4) activation plays a major role in triggering oxidative stress (OS) and inflammation implicated in the pathogenesis of ulcerative colitis (UC). Due to sophorolipids (SLs) antioxidant and anti-inflammatory properties, they are interestingly becoming more valued for their potential effectiveness in treating a variety of diseases. This study was designed to explore the effect of SLs produced by microbial conversion of Moringa oleifera oil cake using isolated yeast Yarrowia lipolytica against UC induced by acetic acid (AA) in rats.

METHODS

The produced SLs were identified by FTIR, 1H NMR and LC-MS/MS spectra, and administered orally for 7 days (200 mg/kg/day) before AA (2 ml, 4% v/v) to induce UC intrarectally on day eight. Biochemically, the levels of TLR-4, c-Jun N-terminal kinase (JNK), nuclear factor kappa B-p65 (NFκB-p65), interleukin-1beta (IL-1β), malondialdehyd, glutathione, Bax/Bcl2 ratio and the immunohistochemical evaluation of inducible nitric oxide synthase and caspase-3 were assayed.

KEY FINDINGS

SLs significantly reduced OS, inflammatory and apoptotic markers in AA-treated rats, almost like the reference sulfasalazine.

CONCLUSIONS

This study provided a novel impact for SLs produced by microbial conversion of M. oleifera oil cake against AA-induced UC in rats through hampering the TLR-4/p-JNK/NFκB-p65 signalling pathway.

The Role of the Human Gut Microbiome in Inflammatory Bowel Disease and Radiation Enteropathy

The human gut microbiome plays a key role in regulating host physiology. In a stable state, both the microbiota and the gut work synergistically. The overall homeostasis of the intestinal flora can be affected by multiple factors, including disease states and the treatments given for those diseases. In this review, we examine the relatively well-characterised abnormalities that develop in the microbiome in idiopathic inflammatory bowel disease, and compare and contrast them to those that are found in radiation enteropathy. We discuss how these changes may exert their effects at a molecular level, and the possible role of manipulating the microbiome through the use of a variety of therapies to reduce the severity of the underlying condition.

Different panel of toll-like receptors expression during chronic Schistosoma mansoni infection in experimental animals

BACKGROUND

Many studies have reported the immunomodulatory effect of helminths to avoid the lethal immunopathology. During schistosomiasis, the immune response is orchestrated by toll-like receptors (TLRs). Modulating TLRs can alter the function of antigen presentation cells with the shift of the host's Th1 response to a dominant regulatory Th2 response. The objective of our study was to clarify which TLRs are related to the immune response of chronic Schistosoma infection.

METHODS

The study animals were divided into two groups; group I: uninfected mice; control group and group II: Schistosoma mansoni infected mice. mRNA expression of TLR2, 3, 4, 7, and 9 in different organs (liver, large intestine, and spleen) were assessed on day 90 post-infection.

RESULTS

TLR gene expression has changed depending on the tissue studied as the mRNA level of TLR2, TLR7, and TLR9 were significantly upregulated in all examined organs while TLR3 expression showed only significant upregulation in the liver of infected mice. On the other hand, TLR4 expression was significantly upregulated in the liver while significantly downregulated in the large intestine.

CONCLUSION

This study provides a better understanding of TLRs profile in different organs against S. mansoni parasites during the chronic phase of infection.

Cellular Immune Signal Exchange From Ischemic Stroke to Intestinal Lesions Through Brain-Gut Axis

As a vital pivot for the human circulatory system, the brain-gut axis is now being considered as an important channel for many of the small immune molecules’ transductions, including interleukins, interferons, neurotransmitters, peptides, and the chemokines penetrating the mesentery and blood brain barrier (BBB) during the development of an ischemic stroke (IS). Hypoxia-ischemia contributes to pituitary and neurofunctional disorders by interfering with the molecular signal release and communication then providing feedback to the gut. Suffering from such a disease on a long-term basis may cause the peripheral system’s homeostasis to become imbalanced, and it can also lead to multiple intestinal complications such as gut microbiota dysbiosis (GMD), inflammatory bowel disease (IBD), necrotizing enterocolitis (NEC), and even the tumorigenesis of colorectal carcinoma (CRC). Correspondingly, these complications will deteriorate the cerebral infarctions and, in patients suffering with IS, it can even ruin the brain’s immune system. This review summarized recent studies on abnormal immunological signal exchange mediated polarization subtype changes, in both macrophages and microglial cells as well as T-lymphocytes. How gut complications modulate the immune signal transduction from the brain are also elucidated and analyzed. The conclusions drawn in this review could provide guidance and novel strategies to benefit remedies for both IS and relative gut lesions from immune-prophylaxis and immunotherapy aspects.

Toll-Like Receptors as Drug Targets in the Intestinal Epithelium

Toll-like receptors (TLRs) receptors are responsible for initiation of inflammatory responses by their recognition of molecular patterns present in invading microorganisms (such as bacteria, viruses or fungi) or in molecules released following tissue damage in disease states. Expressed in the intestinal epithelium, they initiate an intracellular signalling cascade in response to molecular patterns resulting in the activation of transcription factors and the release of cytokines, chemokines and vasoactive molecules. Intestinal epithelial cells are exposed to microorganisms on a daily basis and form part of the primary defence against pathogens by using TLRs. TLRs and their accessory molecules are subject to tight regulation in these cells so as to not overreact or react in unnecessary circumstances. TLRs have more recently been associated with chronic inflammatory diseases as a result of inappropriate regulation, this can be damaging and lead to chronic inflammatory diseases such as inflammatory bowel disease (IBD). Targeting Toll-like receptors offers a potential therapeutic approach for IBD. In this review, the current knowledge on the TLRs is reviewed along with their association with intestinal diseases. Finally, compounds that target TLRs in animal models of IBD, clinic trials and their future merit as targets are discussed.

Anti-Ulcerative Effect of Curcumin-Galactomannoside Complex on Acetic Acid-Induced Experimental Model by Inhibiting Inflammation and Oxidative Stress

Ulcerative colitis (UC) is a chronic inflammatory bowel disease that affects the mucosa and submucosa of colon. The pathogenesis of ulcerative colitis (UC) is related to reduced antioxidant capacity and increased inflammatory processes. Reactive oxygen metabolites are the potent inflammatory mediators that may be involved in tissue injury in inflammatory bowel disease. Conventional drug therapies for UC come with a myriad of side effects which further raise the need for natural bioactive agents. Curcumin has proven to be beneficial in the prevention and treatment of a number of inflammatory diseases, but due its poor bioavailability, the therapeutic applications are limited. Thus, to enhance its bioavailability, a new formulation - curcumin-galactomannoside (CGM)- was made by complexing curcumin with galactomannans derived from fenugreek. The present study aims to evaluate the effects of CGM on experimental UC model. Adult male Wistar rats were divided into 5 groups: normal control rats (NC); ulcerative colitis control rats (UC); UC + sulfasalazine (SS) treated; UC + curcumin (CM) treated; and UC + CGM supplemented for 21 days. The colonic mucosal injury was assessed by macroscopic and histological examination, along with evaluation of antioxidant status, inflammatory mediators, and gene expressions. Administration of CGM significantly enhanced antioxidant activities and decreased the level of inflammatory mediators and also suppressed the expression of inflammatory markers as compared with other groups. In conclusion, findings from these results reveal that CGM exerts marked curative effects on acute experimental colitis, possibly by regulating the antioxidant status and modulating inflammatory cascade.

The role of dietary polyphenols in inflammatory bowel disease: A possible clue on the molecular mechanisms involved in the prevention of immune and inflammatory reactions

Inflammatory bowel disease (IBD) is one of the major complications of the gastrointestinal tract, characterized by chronic inflammation, which disturbs the quality of life of the affected individuals. Genetic predisposition, immune, inflammatory, and enzyme-mediated signaling cascades are the primary mechanisms involved in the pathogenesis of the disease. Currently, the treatment strategy involves the maintenance of remission and induction of inflammation by anti-inflammatory agents and immune suppressants. Polyphenol-containing diets, including fruits and vegetables of regular use, possess anti-inflammatory, and antioxidant potential through the inhibition of major contributing pathways to IBD. This review discusses the role of these dietary polyphenols in downregulating the major signaling cascades in IBD. Our review encourages the development of nutritional strategies to improve the efficiency of current therapies for IBD and reduce the risks of side effects associated with conventional therapy. PRACTICAL APPLICATIONS: At present, almost every third person in society is under stress and having chronic disorders like diabetes, arthritis, allergy, cardiovascular disease, IBD, etc. This insists on the direct/indirect role of changes in the lifestyle for such deterioration in society. This review would emphasize the medicinal value of polyphenols present in fruits and vegetables for chronic inflammatory disorders. This concept portrays the food components which have the potential to promote health, improve general well-being, and reduce the risk of IBD. We propose to add fruits with bioactive polyphenols in the regular diet to help in preventing the immune-mediated intestinal chronic inflammatory syndrome and reduce the risks of colorectal cancer development.

Toll-like Receptors and Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is one relapsing and lifelong disease that affects millions of patients worldwide. Increasing evidence has recently highlighted immune-system dysfunction, especially toll-like receptors (TLRs)-mediated innate immune dysfunction, as central players in the pathogenesis of IBD. TLRs and TLR-activated signaling pathways are involved not only in the pathogenesis but also in the efficacy of treatment of IBD. By understanding these molecular mechanisms, we might develop a strategy for relieving the experience of long-lasting suffering of those patients and improving their quality of life. The purpose of this review article is to summarize the potential mechanisms of TLR signaling pathways in IBD and the novel potential therapeutic strategies against IBD.