Expression of Toll-like receptor 4, CD14, and NF-κB in Chinese patients with ulcerative colitis

Gut instinct: harnessing the power of probiotics to tame pathogenic signaling pathways in ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD) marked by persistent inflammation of the mucosal lining of the large intestine, leading to debilitating symptoms and reduced quality of life. Emerging evidence suggests that an imbalance of the gut microbiota plays a crucial role in UC pathogenesis, and various signaling pathways are implicated in the dysregulated immune response. Probiotics are live microorganisms that confer health benefits to the host, have attracted significant attention for their potential to restore gut microbial balance and ameliorate inflammation in UC. Recent studies have elucidated the mechanisms by which probiotics modulate these signaling pathways, often by producing anti-inflammatory molecules and promoting regulatory immune cell function. For example, probiotics can inhibit the nuclear factor-κB (NF-κB) pathway by stabilizing Inhibitor of kappa B alpha (IκBα), dampening the production of proinflammatory cytokines. Similarly, probiotics can modulate the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway, suppressing the activation of STAT1 and STAT3 and thus reducing the inflammatory response. A better understanding of the underlying mechanisms of probiotics in modulating pathogenic signaling pathways in UC will pave the way for developing more effective probiotic-based therapies. In this review, we explore the mechanistic role of probiotics in the attenuation of pathogenic signaling pathways, including NF-κB, JAK/STAT, mitogen-activated protein kinases (MAPKs), Wnt/β-catenin, the nucleotide-binding domain (NOD)-, leucine-rich repeat (LRR)- and pyrin domain-containing protein 3 (NLRP3) inflammasome, Toll-like receptors (TLRs), interleukin-23 (IL-23)/IL-17 signaling pathway in UC.

Role of long non-coding RNA in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a group of recurrent chronic inflammatory diseases, including Crohn's disease (CD) and ulcerative colitis (UC). Although IBD has been extensively studied for decades, its cause and pathogenesis remain unclear. Existing research suggests that IBD may be the result of an interaction between genetic factors, environmental factors and the gut microbiome. IBD is closely related to non-coding RNAs (ncRNAs). NcRNAs are composed of microRNA(miRNA), long non-coding RNA(lnc RNA) and circular RNA(circ RNA). Compared with miRNA, the role of lnc RNA in IBD has been little studied. Lnc RNA is an RNA molecule that regulates gene expression and regulates a variety of molecular pathways involved in the pathbiology of IBD. Targeting IBD-associated lnc RNAs may promote personalized treatment of IBD and have therapeutic value for IBD patients. Therefore, this review summarized the effects of lnc RNA on the intestinal epithelial barrier, inflammatory response and immune homeostasis in IBD, and summarized the potential of lnc RNA as a biomarker of IBD and as a predictor of therapeutic response to IBD in the future.

Natural flavone tricin exerted anti-inflammatory activity in macrophage via NF-κB pathway and ameliorated acute colitis in mice

BACKGROUND

Ulcerative colitis is a subtype of inflammatory bowel disease, characterized by relapsing inflammation in the gastrointestinal tract with limited treatment options. Previous studies suggested that the natural compound tricin, a flavone isolated from rice bran, could suppress chemically-induced colitis in mice, while our recent study also demonstrated the anti-metastatic effect of tricin in colon tumor-bearing mice.

HYPOTHESIS/PURPOSE

Here we further investigated the underlying mechanism of the inhibitory effects of tricin on lipopolysaccharides-activated macrophage RAW264.7 cells and explored the efficacy of tricin in acute colitis mouse model induced by 4.5% dextran sulfate sodium (DSS) for 7 days.

METHODS

Tricin (75, 100, and 150 mg/kg) or the positive control drug sulfasalazine (200 mg/kg) were orally administered to mice for 7 days. Stool consistency scores, stool blood scores, and body weight were recorded daily. Disease activity index (DAI) was examined on day 7, and colon tissues were collected for biochemical analyses. The fecal microbiome of colitis mice after tricin treatment was characterized for the first time in this study using 16S rDNA amplicon sequencing.

RESULTS

Results showed that tricin (50 µM) remarkably reduced nitric oxide production in lipopolysaccharides-activated RAW264.7 cells and the anti-inflammatory activity of tricin was shown to act through the NF-κB pathway. Besides, tricin treatment at 150 mg/kg significantly reversed colon length reduction, reduced myeloperoxidase activities and DAI scores, as well as restored the elevated myeloid-derived suppressive cells population in acute colitis mice. The influence from DSS on gut microbiota, such as the increased population of Proteobacteria phylum and Ruminococcaceae family, was shown to be relieved after tricin treatment.

CONCLUSION

Our present study firstly demonstrated that tricin ameliorated acute colitis by improving colonic inflammation and modulating gut microbiota profile, which supports the potential therapeutic use of tricin for colitis treatment.

The Protection of Crocin Against Ulcerative Colitis and Colorectal Cancer via Suppression of NF-κB-Mediated Inflammation

Background: In China, the incidence of ulcerative colitis (UC) is increasing every year, but the etiology of UC remains unclear. UC is known to increase the risk of colorectal cancer (CRC). The aim of this study was to investigate the protective effects of crocin against UC and CRC in mouse models.

Methods: Crocin was used to treat the dextran sodium sulfate (DSS)-induced UC mice for 3 weeks, and Apc^MinC/Gpt mice with colorectal cancer for 8 weeks. Proteomics screening was used to detect changes in the protein profiles of colon tissues of UC mice. Enzyme-linked immunosorbent assays and western blot were used to verify these changes.

Results: Crocin strongly reduced the disease activity index scores of UC mice, and improved the pathological symptoms of the colonic epithelium. The anti-inflammatory effects of crocin were indicated by its regulation of the activity of various cytokines, such as interleukins, via the modulation of nuclear factor kappa-B (NF-κB) signaling. Crocin significantly suppressed tumor growth in Apc^MinC/Gpt mice and ameliorated pathological alterations in the colon and liver, but had no effects on spleen and kidney. Additionally, crocin significantly decreased the concentrations of interleukins and tumor necrosis factor-α in the sera and colon tissues, suggesting its anti-inflammatory effects related to NF-κB signaling. Finally, 12-h incubation of SW480 cells with crocin caused cell cycle arrest, enhanced the apoptotic rate, promoted the dissipation of mitochondrial membrane potential, and the over-accumulation of reactive oxygen species. From the theoretical analyses, phosphorylated residues on S536 may enhance the protein-protein interactions which may influence the conformational changes in the secondary structure of NF-κB.

Conclusion: The protective effects of crocin on UC and CRC were due to its suppression of NF-κB-mediated inflammation.

Targeting NF-κB pathway for treating ulcerative colitis: comprehensive regulatory characteristics of Chinese medicines

Nuclear factor-kappa B (NF-κB) is a kind of multi-functional nuclear transcription factor involved in regulating gene transcription to influence pathological evolution of inflammatory and immune diseases. Numerous literature evidence that NF-κB pathway plays an essential role in pathogenic development of ulcerative colitis (UC). UC is a chronic non-specific inflammatory bowel disease, and until now, therapeutic agents for UC including aminosalicylates, corticosteroids and immune inhibitors still cannot exert satisfied effects on patients. In recent years, Chinese medicines suggest the advantages of alleviating symptoms and signs, decreasing side-effects and recurrence, whose one of mechanisms is related to regulation of NF-κB pathway. In this review, we categorize Chinese medicines according to their traditional therapeutic functions, and summarize the characteristics of Chinese medicines targeting NF-κB pathway in UC treatment. It indicates that 85 kinds of Chinese medicines’ compounds and formulae can directly act on NF-κBp65; while 58 Chinese medicines’ ingredients and formulae indirectly suppress NF-κBp65 by regulation of its upstream or other related pathways. Moreover, by the analysis of Chinese medicines’ category based on their traditional functions, we conclude the category of dampness-drying and detoxificating medicine targeting NF-κB pathway accounts for primary status for amelioration of UC. Simultaneously, this review also contributes to the choices of Chinese medicine category and provides curative potential of Chinese medicines for clinical UC treatment.

Polysaccharide from flammuliana velutipes improves colitis via regulation of colonic microbial dysbiosis and inflammatory responses

The aim of this study is to investigate whether Flammuliana Velutipes Polysaccharide (FVP) could aid in the prevention of colitis. Effect of FVP on colitis was evaluated using dextran sulfate sodium (DSS)-induced colitis in rats. Influence of FVP on the expression of inflammation related biomarkers and signal pathway element of TLR4\NF-κB were assessed. The composition and taxonomy of colonic microbiota were analyzed by 16S rDNA high throughput sequencing, and the concentrations of caecal short fatty chain acids were assessed by chromatography-mass spectrometry. Our results showed that FVP treatment could regulate the colonic microbial dysbiosis and promote the levels of caecal short fatty chain acids, leading to down-regulation of TLR4\NF-κB signal pathway, which finally ameliorate the colitis. Thus, the present study is the first attempt to elucidate the effect of FVP on colitis and support the potential application of FVP as a functional food ingredient or preventive drugs for colitis.

Effect of Clostridium perfringens type C on TLR4/MyD88/NF-κB signaling pathway in piglet small intestines

Clostridium perfringens (C. perfringens), a Gram-positive bacterium, is one of the main causing piglet diarrhea, which leads serious economic loss in the world swine industries. Generally, the innate immune response plays a critical role in host defense against pathogen invasion. TLR4, a member of the TLR (Toll-like receptor) family, has been considered to implicate in the host immune responses and induce secretion of inflammatory cytokines during bacterial infection. However, little is clear about the effects of TLR4 and key signaling genes in the process of piglet inflammatory and immune responses after C. perfringens infection. This study aims to explore the effect of C. perfringens type C infection on the key mRNAs of TLR4/MyD88/NF-κB signaling pathways during the process of piglet diarrhea. In this study, the expressions of TLR4 and other key mRNAs in the TLR4/MyD88/NF-κB signaling pathways were quantified in piglet ileum and jejunum tissues among IR (intestinal resistance), IS (intestinal susceptibility) and IC (intestinal control) groups by qPCR and Western blot methods, the concentrations of pro-inflammatory cytokines in intestinal tissues and serum immunoglobulins were also tested by ELISA kits. Results showed that compared to IC group, expressions of ileum TLR4 and TNF-α was significantly increased in the IS and IR groups, specially TBK1 gene; the expressions of ileum TLR2, TRAF6, MyD88 and IL-8 mRNAs was significantly up-regulated in the IS group, the expressions of TLR9, NF-κB, IL-6, IFN-γ and MAPK1 genes were not significant differences among the IR, IS and IC groups. Meanwhile, the protein levels of TLR4, HMGB1 and NF-κB were higher in the IS and IR groups. The levels of jejunum IFN-γ and IL-6, ileum IL-6 and IL-12 were risen in the IR group. Serum immunoglobulin IgA and IgG in the IR and IS groups reached a peak on the 72 h and 48 h post infection, respectively. These findings suggest that C. perfringens type C infection induces host immune responses involving in the TLR4/MyD88/NF-κB signaling pathways in ileum than in jejunum, which may provide valuable information for innate immune mechanisms involved in regulation of piglet diarrhea caused by C. perfringens type C infection.

Long noncoding RNA ANRIL contributes to the development of ulcerative colitis by miR-323b-5p/TLR4/MyD88/NF-κB pathway

The aim of this study was to investigate the role and possible mechanism of long noncoding RNA ANRIL in the development of ulcerative colitis (UC). The expression of ANRIL in colonic mucosa tissues collected from the sigmoid colon of UC patients and healthy control was determined. Subsequently, fetal human cells (FHCs) were treated with lipopolysaccharide (LPS) to stimulate UC-caused inflammatory injury, followed by detection of the effects of suppression of ANRIL on cell viability, apoptosis and cytokines production in LPS-stimulated FHCs. Moreover, the regulatory relationship between ANRIL and miR-323b-5p as well as the target relationship between miR-323b-5p and TLR4 were investigated. Furthermore, the effects of ANRIL/miR-323b-5p axis on the activation of TLR4/MyD88/NF-κB pathway in LPS-stimulated FHCs were investigated. LncRNA ANRIL was highly expressed in colonic mucosa tissues of UC patients. In addition, LPS markedly induced cell injury in FHC cells (inhibited cell viability and promoted cell apoptosis and cytokine production). Suppression of ANRIL alleviated LPS-induced injury in FHC cells, which was achieved by negatively regulating miR-323b-5p. Moreover, miR-323b-5p negatively regulated TLR4 expression and TLR4 was a target of miR-323b-5p. Knockdown of TLR4 reversed the effects of miR-323b-5p suppression on LPS-induced injury in LPS-stimulated FHCs. Furthermore, the effects of ANRIL on LPS-induced cell injury were achieved by TLR4/MyD88/NF-κB pathway. Our data indicate that suppression of ANRIL may inhibit the development of UC by regulating miR-323b-5p/TLR4/MyD88/NF-κB pathway. ANRIL/miR-323b-5p/TLR4/MyD88/NF-κB pathway may provide a new strategy for UC therapy.

Effect of Wenshen Jiangzhuo Huayu decoction on the expression of CD14, TLR-4 and NF-κB in ulcerative colitis in mice

AIM: To explore the mechanism by which Wenshen Jiangzhuo Huayu decoction prevents ulcerative colitis by detecting the expression of CD14, TLR-4 and NF-κB in colon mucosa of mice with ulcerative colitis.

METHODS: Sixty Balb/c mice were randomly and equally divided into five groups: normal group, blank group, and three intervention groups (low, medium, high doses). Except for the normal group, the other groups were given orally 5% DSS for four weeks. Mice in the intervention groups were intragastrically administered with different doses of Wenshen Jiangzhuo Huayu decoction for four weeks, and the blank group was intragastrically administered with normal saline for the same duration. Colon histomorphology was assayed by naked eyes and light microscopy. The expression of CD14, TLR-4 and NF-κBp65 was detected by immunohistochemistry and real-time PCR.

RESULTS: Hyperemia, edema and ulcer were noted in the colon mucosa of mice in the blank group, while the changes in the intervention groups were characterized by hyperemia and edema. There was a significant difference in DAI index between the blank group and intervention groups (7.36 ± 0.27 vs 3.58 ± 0.37, P < 0.05). The expression of CD14, TLR-4 and NF-κBp6 was up-regulated in the blank group compared to the normal group. However, the expression of CD14, TLR-4 and NF-κBp6 was significantly down-regulated in the intervention groups compared to the blank group (1.98 ± 0.33 vs 3.17 ± 0.55, 1.75 ± 0.32 vs 3.86 ± 0.75, 1.64 ± 0.27 vs 4.75 ± 0.52, all P < 0.05).

CONCLUSION: Wenshen Jiangzhuo Huayu decoction may prevent ulcerative colitis by regulating the CD14/TLR-4-NF-κB signal pathway.