Chromatin remodeling complex in Treg function

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.

Molecular mechanism of curcumin action in signaling pathways: Review of the latest research

Recently, many studies have been conducted trying to explain the molecular mechanism of curcumin action in various pathological states of the cell and the organism. Curcumin is considered to play a role in the regulation of T-lymphocytes function in the lymphoid tissue of the large intestine, apoptosis of the human papilloma and the activity of the 26S proteasome, and p53 level. Research works have shown that curcumin in tumor can regulate reactive oxygen species (ROS) and cytosolic calcium ion level as well as affect other signaling molecules [nuclear factor kappa B (NF-KB), cytokines] triggering endoplasmic reticulum and mitochondrial stress, and thus contributing to death of cancer cells. Curcumin can also arrest of the cell cycle in the G2/M phase leading to apoptosis and/or reduction in cancer cells proliferation. Moreover, curcumin is capable of crossing the blood-brain barrier, and thus it may protect the neurons from oxidative stress and inflammation. Finally, curcumin may play a role in cardiological protection and it is possible to use it in the protection of liver and spleen against oxidative and inflammatory injury. Among signaling pathways regulated by curcumin, the most important seem to be those related with regulation of oxidative stress and inhibition of NF-кB activity.

Curcumin improves regulatory T cells in gut-associated lymphoid tissue of colitis mice

AIM: To explore the probable pathway by which curcumin (Cur) regulates the function of Treg cells by observing the expression of costimulatory molecules of dendritic cells (DCs).

METHODS: Experimental colitis was induced by administering 2, 4, 6-trinitrobenzene sulfonic acid (TNBS)/ethanol solution. Forty male C57BL/6 mice were randomly divided into four groups: normal, TNBS + Cur, TNBS + mesalazine (Mes) and TNBS groups. The mice in the TNBS + Cur and TNBS +Mes groups were treated with Cur and Mes, respectively, while those in the TNBS group were treated with physiological saline for 7 d. After treatment, the curative effect of Cur was evaluated by colonic weight, colonic length, weight index of the colon, and histological observation and score. The levels of CD4⁺CD25+Foxp3⁺ T cells (Treg cells) and costimulatory molecules of DCs were measured by flow cytometry. Also, related cytokines were analyzed by enzyme-linked immunosorbent assay.

RESULTS: Cur alleviated inflammatory injury of the colonic mucosa, decreased colonic weigh and histological score, and restored colonic length. The number of Treg cells was increased, while the secretion of TNF-α, IL-2, IL-6, IL-12 p40, IL-17 and IL-21 and the expression of costimulatory molecules (CD205, CD54 [ICAM-1], TLR4, CD252[OX40 L], CD256 [RANK] and CD254 [RANK L]) of DCs were notably inhibited in colitis mice treated with Cur.

CONCLUSION: Cur potentially modulates activation of DCs to enhance the suppressive functions of Treg cells and promote the recovery of damaged colonic mucosa in inflammatory bowel disease.