Gene Expression of Transient Receptor Potential Channels in Peripheral Blood Mononuclear Cells of Inflammatory Bowel Disease Patients

The Role of the TRPV4 Channel in Intestinal Physiology and Pathology

The transient receptor potential vanilloid 4 channel (TRPV4) is an important member of the TRP superfamily of cation channels. The channel can be activated by different physical and chemical stimuli, such as heat, osmotic, and mechanical stress. It regulates the release of nociceptive peptides (substance P and calcitonin gene-related peptide), and mediates neurogenic inflammation, which indicates the involvement of TRPV4 as a nociceptor. Previous studies show that TRPV4 regulates the contraction of intestinal smooth muscle, mucosal barrier permeability, intestinal ion transport, activation of submucosal enteric neurons, and generation of immune cells. TRPV4 is involved in various pathophysiological activities, and altered TRPV4 expression has been detected in some intestinal diseases (IBD, IBS, intestinal tumors, etc). Evidence indicates that TRPV4 plays a noxious role in intestinal barrier function when the intestine is damaged. This review focuses on the role of the TRPV4 channel in the physiological and pathological functions of the intestine, and evaluates the potential clinical significance to target TRPV4 channel in the treatment of intestinal diseases.

Study on the Therapeutic Effects and Mechanisms of Gintonin in Irritable Bowel Syndrome and Its Relationship with TRPV1, TRPV4, and NaV1.5

Irritable bowel syndrome (IBS) is a gastrointestinal (GI) disease accompanied by changes in bowel habits without any specific cause. Gintonin is a newly isolated glycoprotein from ginseng that is a lysophosphatidic acid (LPA) receptor ligand. To investigate the efficacy and mechanisms of action of gintonin in IBS, we developed a zymosan-induced IBS murine model. In addition, electrophysiological experiments were conducted to confirm the relevance of various ion channels. In mice, gintonin restored colon length and weight to normal and decreased stool scores, whilst food intake remained constant. Colon mucosal thickness and inflammation-related tumor necrosis factor-α levels were decreased by gintonin, along with a reduction in pain-related behaviors. In addition, the fecal microbiota from gintonin-treated mice had relatively more Lactobacillaceae and Lachnospiraceae and less Bacteroidaceae than microbiota from the control mice. Moreover, gintonin inhibited transient receptor potential vanilloid (TRPV) 1 and TRPV4 associated with visceral hypersensitivity and voltage-gated Na+ 1.5 channels associated with GI function. These results suggest that gintonin may be one of the effective components in the treatment of IBS.

Ca2+-Dependent Processes of Innate Immunity in IBD

IBD is an uncontrolled inflammatory condition of the gastrointestinal tract, which mainly manifests in two forms: ulcerative colitis (UC) and Crohn's disease (CD). The pathogenesis of IBD appears to be associated with an abnormal response of innate and adaptive immune cells. Innate immunity cells, such as macrophages, mast cells, and granulocytes, can produce proinflammatory (e.g., TNF-α) and oxidative stress (ROS) mediators promoting intestinal damage, and their abnormal responses can induce an imbalance in adaptive immunity, leading to the production of inflammatory cytokines that increase innate immune damage, abate intestinal barrier functions, and aggravate inflammation. Considering that Ca2+ signalling plays a key role in a plethora of cellular functions, this review has the purpose of deepening the potential Ca2+ involvement in IBD pathogenesis.

A Spatially Stable Crystal-Particle Gel to Trap Patchouli Oil for Efficient Colonic Drug Delivery

Patchouli oil has exhibited remarkable efficacy in the treatment of colitis. However, its volatility and potential irritancy are often drawbacks when extensively used in clinical applications. Oil gel is a semisolid and thermoreversible system that has received extensive interest for its solubility enhancement, inhibition of bioactive component recrystallization, and the facilitation of controlled bioactive release. Therefore, we present a strategy to develop an oil gel formulation that addresses this multifaceted problem. Notably, a patchouli oil gel formulation was designed to solidify and trap patchouli oil into a spatially stable crystal-particle structure and colonic released delivery, which has an advantage of the stable structure and viscosity. The patchouli oil gel treatment of zebrafish with colitis improved goblet cells and decreased macrophages. Additionally, patchouli oil gel showed superior advantages for restoring the tissue barrier. Furthermore, our investigative efforts unveiled patchouli oil's influence on TRP channels, providing evidence for its potential role in mechanisms of anti-inflammatory action. While the journey continues, these preliminary revelations provide a robust foundation for considering the adoption of patchouli oil gel as a pragmatic intervention for managing colitis.

Exploring Microbial Metabolite Receptors in Inflammatory Bowel Disease: An In Silico Analysis of Their Potential Role in Inflammation and Fibrosis

Metabolites produced by dysbiotic intestinal microbiota can influence disease pathophysiology by participating in ligand-receptor interactions. Our aim was to investigate the differential expression of metabolite receptor (MR) genes between inflammatory bowel disease (IBD), healthy individuals (HIs), and disease controls in order to identify possible interactions with inflammatory and fibrotic pathways in the intestine. RNA-sequencing datasets containing 643 Crohn's disease (CD) patients, 467 ulcerative colitis (UC) patients and 295 HIs, and 4 Campylobacter jejuni-infected individuals were retrieved from the Sequence Read Archive, and differential expression was performed using the RaNA-seq online platform. The identified differentially expressed MR genes were used for correlation analysis with up- and downregulated genes in IBD, as well as functional enrichment analysis using a R based pipeline. Overall, 15 MR genes exhibited dysregulated expression in IBD. In inflamed CD, the hydroxycarboxylic acid receptors 2 and 3 (HCAR2, HCAR3) were upregulated and were associated with the recruitment of innate immune cells, while, in the non-inflamed CD ileum, the cannabinoid receptor 1 (CNR1) and the sphingosine-1-phospate receptor 4 (S1PR4) were downregulated and were involved in the regulation of B-cell activation. In inflamed UC, the upregulated receptors HCAR2 and HCAR3 were more closely associated with the process of TH-17 cell differentiation, while the pregnane X receptor (NR1I2) and the transient receptor potential vanilloid 1 (TRPV1) were downregulated and were involved in epithelial barrier maintenance. Our results elucidate the landscape of metabolite receptor expression in IBD, highlighting associations with disease-related functions that could guide the development of new targeted therapies.

Non-electrophysiological techniques targeting transient receptor potential (TRP) gene of gastrointestinal tract

Transient receptor potential (TRP) channels are cation channels related to a wide range of physical and chemical stimuli, they are expressed all along the gastrointestinal system, and a myriad of diseases are often associated with aberrant expression or mutation of the TRP gene, suggesting that TRPs are promising targets for drug therapy. Therefore, a better understanding of the information of TRPs in health and disease could facilitate the development of effective drugs for the treatment of gastrointestinal diseases like IBD. But there are very few generalizations about the experimental techniques studied in this field. In view of the promise of TRP as a therapeutic target, we discuss experimental methods that can be used for TRPs including their distribution, function and interaction with other proteins, as well as some promising emerging technologies to provide experimental methods for future studies.

Function of TRP channels in monocytes/macrophages

The transient receptor potential channel (TRP channel) family is a kind of non- specific cation channel widely distributed in various tissues and organs of the human body, including the respiratory system, cardiovascular system, immune system, etc. It has been reported that various TRP channels are expressed in mammalian macrophages. TRP channels may be involved in various signaling pathways in the development of various systemic diseases through changes in intracellular concentrations of cations such as calcium and magnesium. These TRP channels may also intermingle with macrophage activation signals to jointly regulate the occurrence and development of diseases. Here, we summarize recent findings on the expression and function of TRP channels in macrophages and discuss their role as modulators of macrophage activation and function. As research on TRP channels in health and disease progresses, it is anticipated that positive or negative modulators of TRP channels for treating specific diseases may be promising therapeutic options for the prevention and/or treatment of disease.

Predictive value of TRPV2 expression from peripheral blood mononuclear cells on the early recurrence of atrial fibrillation after radiofrequency catheter ablation

BACKGROUND

Recent study has shown that the transient receptor potential vanilloid 2 (TRPV2) channel was exclusively upregulated in patients with atrial fibrillation (AF), and that this overexpression might be detrimental for occurrence and maintenance of AF. We aimed to characterize the expression levels of TRPV2 mRNA in peripheral blood mononuclear cells (PBMCs) with/without early recurrence of atrial fibrillation (ERAF) after radiofrequency catheter ablation (RFCA), and to find a reliable predictor for ERAF.

METHODS

65 patients of AF, who underwent RFCA successfully, then divided into two groups according to ERAF during following 3 months. PBMCs were isolated from whole blood by Ficoll gradient centrifugation before and after RFCA. Gene set enrichment analysis was performed to evaluate TRPV channels expression levels and Kyoto Encyclopedia of Genes and Genomes (KEGG) mapping was used for pathway enrichment analysis.

RESULTS

There was no significant difference in the TRPV2 mRNA expression level between the two groups before RFCA, while without ERAF group of TRPV2 expression was markedly reduced compared to ERAF group after RFCA. Moreover, the number of TRPV2 expression was confirmed as an independent predictor for the first time through receiver operating characteristic and Kaplan-Meier survival curve analysis. It should be pointed out that the above results were only used to predict ERAF, and have no predictive significance for late recurrence of atrial fibrillation according to the current data. Additionally, ERAF was inversely correlated with P wave dispersion. KEGG mapping further clustered 41 pathways, revealing that ''cyclic guanosine monophosphate-protein kinase G signaling pathway'' was significantly enriched.

CONCLUSIONS

We firstly assume that downregulated expression of peripheral TRPV2 appear in patients without ERAF after RFCA. TRPV2 may thus represent a novel predictor of early phase after successful radiofrequency ablation.

In vitro models and ex vivo systems used in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic, relapsing gastrointestinal condition. Ulcerative colitis and Crohn’s disease are types of inflammatory bowel disease. Over many decades, the disease has been a topic of study, with experts still trying to figure out its cause and pathology. Researchers have established many in vivo animal models, in vitro cell lines, and ex vivo systems to understand its cause ultimately and adequately identify a therapy. However, in vivo animal models cannot be regarded as good models for studying IBD since they cannot completely simulate the disease. Furthermore, because species differences are a crucial subject of concern, in vitro cell lines and ex vivo systems can be employed to recreate the condition properly. In vitro models serve as the starting point for biological and medical research. Ex vivo and in vitro models for replicating gut physiology have been developed. This review aims to present a clear understanding of several in vitro and ex vivo models of IBD and provide insights into their benefits and limits and their value in understanding intestinal physiology.

Major Phytocannabinoids and Their Related Compounds: Should We Only Search for Drugs That Act on Cannabinoid Receptors?

The most important discoveries in pharmacology, such as certain classes of analgesics or chemotherapeutics, started from natural extracts which have been found to have effects in traditional medicine. Cannabis, traditionally used in Asia for the treatment of pain, nausea, spasms, sleep, depression, and low appetite, is still a good candidate for the development of new compounds. If initially all attention was directed to the endocannabinoid system, recent studies suggest that many of the clinically proven effects are based on an intrinsic chain of mechanisms that do not necessarily involve only cannabinoid receptors. Recent research has shown that major phytocannabinoids and their derivatives also interact with non-cannabinoid receptors such as vanilloid receptor 1, transient receptor ankyrin 1 potential, peroxisome proliferator-activated receptor-gamma or glitazone receptor, G55 protein-coupled receptor, and nuclear receptor, producing pharmacological effects in diseases such as Alzheimer's, epilepsy, depression, neuropathic pain, cancer, and diabetes. Nonetheless, further studies are needed to elucidate the precise mechanisms of these compounds. Structure modulation of phytocannabinoids, in order to improve pharmacological effects, should not be limited to the exploration of cannabinoid receptors, and it should target other courses of action discovered through recent research.

Inflammasome Signaling Regulates the Microbial-Neuroimmune Axis and Visceral Pain in Mice

Interactions between the intestinal microbiota, immune system and nervous system are essential for homeostasis in the gut. Inflammasomes contribute to innate immunity and brain–gut interactions, but their role in microbiota–neuro–immune interactions is not clear. Therefore, we investigated the effect of the inflammasome on visceral pain and local and systemic neuroimmune responses after antibiotic-induced changes to the microbiota. Wild-type (WT) and caspase-1/11 deficient (Casp1 KO) mice were orally treated for 2 weeks with an antibiotic cocktail (Abx, Bacitracin A and Neomycin), followed by quantification of representative fecal commensals (by qPCR), cecal short chain fatty acids (by HPLC), pathways implicated in the gut–neuro-immune axis (by RT-qPCR, immunofluorescence staining, and flow cytometry) in addition to capsaicin-induced visceral pain responses. Abx-treatment in WT-mice resulted in an increase in colonic macrophages, central neuro-immune interactions, colonic inflammasome and nociceptive receptor gene expression and a reduction in capsaicin-induced visceral pain. In contrast, these responses were attenuated in Abx-treated Casp1 KO mice. Collectively, the data indicate an important role for the inflammasome pathway in functional and inflammatory gastrointestinal conditions where pain and alterations in microbiota composition are prominent.

Transient receptor potential (TRP) channels in human colorectal cancer: evidence and perspectives

Colorectal cancer (CRC) is one of the leading causes of death in the civilized world. Transient receptor potential channels (TRPs) are a heterogeneous family of cation channels that play an important role in gastrointestinal physiology. TRPs have been linked with carcinogenesis in the colon and their role as potential therapeutic targets and prognostic biomarkers is under investigation.

Evaluation of Serum Leucine-Rich Alpha-2 Glycoprotein as a New Inflammatory Biomarker of Inflammatory Bowel Disease

Studies on serum leucine-rich alpha-2 glycoprotein (LRG) in inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD), are scarce; the methods for estimating disease activity are less established, particularly for CD. This study is aimed at evaluating the utility of serum LRG as a potential inflammatory marker for IBD and to investigate the LRG gene expression in peripheral blood mononuclear cells (PBMCs) as a possible source of serum LRG. Overall, 98 patients with UC and 96 patients with CD were prospectively enrolled and clinically evaluated; 92 age-matched individuals served as the healthy controls. The blood samples were analyzed for serum LRG levels and routine laboratory parameters. Disease activity was assessed clinically and endoscopically. Finally, LRG gene expression in the PBMCs from a different cohort (41 patients with UC, 34 patients with CD, and 30 healthy controls) was examined. The serum LRG levels were higher during active disease than during inactive disease; additionally, serum LRG levels were positively correlated with clinical disease activity, C-reactive protein (CRP) levels, and other laboratory parameters in patients with UC and CD and with endoscopic disease activity in UC. UC and CD showed comparable areas under the curve (AUC) values for determining clinical remission and differentiating between endoscopic remission associated with LRG and CRP. The levels of LRG mRNA were also increased in PBMCs from patients with UC and CD and reflected disease activity. These data suggest that serum LRG, originated partially from PBMCs, is an inflammatory marker in UC and CD. A large-scale well-designed study should be conducted in the future to more accurately reveal the clinical significance of LRG in patients with IBD.