Anti-inflammatory Effects of Novel P2X4 Receptor Antagonists, NC-2600 and NP-1815-PX, in a Murine Model of Colitis

A comprehensive review of small molecules, targets, and pathways in ulcerative colitis treatment

Ulcerative colitis (UC), a chronic inflammatory bowel disease (IBD), poses significant clinical challenges because of its complex pathophysiology, long-term nature, and the limited efficacy of existing treatments. Small-molecule compounds, particularly those that are able to modulate inflammation-related signaling pathways and, in many cases, occur in nature, offer a promising alternative or supplement to conventional therapies. Studies on molecules for UC therapeutics reported in 1394 publications over the past 30 years were collected from the Web of Science (WOS) database. Only studies that verified therapeutic efficacy through animal experiments were included. Through an analysis of the molecular classes, structures, common targets, and pathways using network pharmacology, we identified 14 classes of compounds, 5 direct-target modules, and 3 crucial downstream pathways. Alkaloids, phenylpropanoids, flavonoids, and terpenes (and their derivatives) appeared most frequently and mainly targeted lipid metabolism, oxidative stress, immune regulation, signaling transduction, and cancer-related pathways. Notably, there has been an increasing trend of applying naturally sourced compounds in both preclinical and clinical trials, especially flavonoids, over the last five years. Although progress in UC research has been made, the majority of studies have focused on the overall therapeutic effects and biomarker alterations, with limited emphasis on the direct targets and underlying mechanisms. These findings highlight the need to explore novel small-molecule therapeutic strategies for UC, focusing on clearly defined targets and precise modes of action.

Unmet needs and future directions of treatment options for chronic cough

INTRODUCTION

Chronic cough is a persistent condition that significantly affects patients' quality of life and poses diagnostic and therapeutic challenges. Traditional anatomical diagnostic approaches often fail to address the underlying mechanisms, leading to suboptimal treatment outcomes.

AREA COVERED

This review aims to summarize the challenges of the management of chronic cough and highlights recent advances of several promising drug candidates in cough trials. PUBMED/CINAHL/Web of Science/Scopus were searched (February 2025).

EXPERT OPINION

Over the past 40 years, chronic cough has evolved from a mere symptom to a recognized disease. A key observation is that hypersensitivity of the afferent vagus and its central projections cause the state of cough hypersensitivity leading to the urge to cough being precipitated by otherwise innocuous stimuli. Clinical trial designs have also advanced, incorporating placebo run-in periods to reduce placebo effects and refining patient-reported outcomes to modern standards. Additionally, the realization that the variability in chronic cough, both diurnal and day-to-day, has highlighted the need for continuous cough monitoring, which has only recently been available consequence to the revolution in electronic applications. However, progress is hindered by a widespread lack of awareness among healthcare professionals and patients, underscoring the urgent need for education on this condition.

Naphtho[1,2-b][1,4]diazepinedione-Based P2X4 Receptor Antagonists from Structure-Activity Relationship Studies toward PET Tracer Development

The P2X4 receptor is implicated in various pathological conditions, including neuropathic pain and cancer. This study reports the development of 1,4-naphthodiazepinedione-based P2X4 receptor antagonists aimed at both therapeutic applications and potential use as PET tracers for imaging P2X4 receptor expression in cancer. Structure-activity relationship studies aided by docking studies and molecular dynamics simulations led to a series of compounds with potent P2X4 receptor antagonism, promising in vitro inhibition of interleukin-1β release in THP-1 cells and suitability for radiolabeling with fluorine-18. The most potent compounds were further evaluated for their physicochemical properties, metabolic stability, and in vivo biodistribution using PET imaging in mice. While these antagonists exhibited strong receptor binding and serum stability, rapid in vivo metabolism limited their potential as PET tracers, highlighting the need for further structural optimization. This study advances the understanding of P2X4 receptor antagonism and underscores the challenges in developing effective PET tracers for this target.

Preparation and preliminary evaluation of a tritium-labeled allosteric P2X4 receptor antagonist

P2X4 receptors are ATP-gated cation channels that were proposed as novel drug targets due to their role in inflammation and neuropathic pain. Only few potent and selective P2X4 receptor antagonists have been described to date. Labeled tool compounds suitable for P2X4 receptor binding studies are lacking. Here, we present a novel allosteric P2X4 receptor antagonist possessing high potency in the low nanomolar range. We describe its tritium-labeling resulting in the P2X4-selective radiotracer [3H]PSB-OR-2020 with high specific activity (45 Ci/mmol; 1.67 TBq/mmol). A radioligand binding assay was developed using human embryonic kidney (HEK293) cell membranes recombinantly expressing the human P2X4 receptor. Competition binding studies with structurally diverse P2X4 receptor antagonists revealed different allosteric binding sites indicating that the new class of P2X4 receptor antagonists, to which PSB-OR-2020 belongs, interacts with an unprecedented allosteric site. [3H]PSB-OR-2020 may become a useful tool for research on P2X4 receptors and for promoting drug development.

Pharmacological differences between human and mouse P2X4 receptor explored using old and new tools

There is growing interest in the P2X4 receptor as a therapeutic target for several cardiovascular, inflammatory and neurological conditions. Key to exploring the physiological and pathophysiological roles of P2X4 is access to selective compounds to probe function in cells, tissues and animal models. There has been a recent growth in selective antagonists for P2X4, though agonist selectivity is less well studied. As there are some known pharmacological differences between P2X receptors from different species, it is important to understand these differences when designing a pharmacological strategy to probe P2X4 function in human tissue and mouse models. Here, we provide a systematic comparison of agonist and antagonist pharmacology in 1321N1 cells expressing either human or mouse P2X4 orthologues. We identify a rank order of agonist potency of ATP > 2-MeSATP > αβmeATP = BzATP > CTP = γ-[(propargyl)-imido]-ATP for human P2X4 and ATP > 2-MeSATP = CTP > ATPγS = γ-[(propargyl)-imido]-ATP = BzATP for mouse. Human P2X4 is not activated by ATPγS but can be activated by αβmeATP. We identify a rank order of antagonist potency of BAY-1797 = PSB-12062 = BX-430 > 5-BDBD > TNP-ATP = PPADS for human P2X4 and BAY-1797 > PSB-12062 = PPADS > TNP-ATP for mouse. Mouse P2X4 is not antagonised by 5-BDBD or BX-430. The study reveals key pharmacological differences between human and mouse P2X4, highlighting caution when selecting tools for comparative studies between human and mouse and ascribing cellular responses of some commonly used agonists to P2X4.

Prokineticin-2 Is Highly Expressed in Colonic Mucosa of Early Parkinson's Disease Patients

BACKGROUND

Elevated levels of prokineticin-2 (PK2), regarded as a protein involved in modulating immune/inflammatory responses, have been detected in the substantia nigra, serum, and olfactory neurons of Parkinson's disease (PD) patients. Of note, emerging evidence suggests that gut alterations, including dysbiosis and enteric inflammation, play a role in PD via the gut-brain axis.

OBJECTIVES

Our goal was to investigate the expression of PK2 in colonic biopsies of PD patients.

METHODS

Mucosal biopsies from the descending colon were obtained in 11 PD patients and five asymptomatic subjects. Biopsy samples were processed for PK2 immunofluorescence and western blot.

RESULTS

We revealed an increased PK2 expression in colonic mucosa from PD patients in the early stages compared to controls. In addition, we found that PK2 was expressed by activated enteric glial cells and macrophages.

CONCLUSIONS

PK2 is highly expressed within neurogenic/inflammatory cells of colonic mucosa from early PD patients, suggesting a potential role of PK2 in gut inflammation, especially in the early stages of PD. © 2024 International Parkinson and Movement Disorder Society.

Lactiplantibacillus plantarum HEAL9 attenuates cognitive impairment and progression of Alzheimer's disease and related bowel symptoms in SAMP8 mice by modulating microbiota-gut-inflammasome-brain axis

Background: Growing evidence highlights the relevance of the microbiota-gut-brain axis in Alzheimer's disease (AD). AD patients display gut dysbiosis, altered intestinal barrier and enteric inflammation that, besides bowel symptoms, can contribute to brain pathology. In this context, the modulation of gut microbiota is emerging as a therapeutical option to halt or slow down central pathology. Herein, we examined the effects of Lactiplantibacillus plantarum HEAL9 in a spontaneous mouse model of AD. Methods: Senescence-accelerated mouse prone 8 (SAMP8) mice and control SAMR1 mice were treated orally with HEAL9 1 × 109 CFU per mouse per day or placebo for two months to evaluate the effects of the probiotic during the earliest stages of AD, before the development of brain pathology. Cognitive impairment, in vivo and in vitro colonic motility, astrocyte and microglia reactive response, brain and colonic amyloid-β1-42 (Aβ1-42) levels, and inflammasome components activation (NLRP3, ASC, caspase-1 and interleukin-1β) were assessed. In addition, gut barrier alterations [circulating lipopolysaccharide-binding protein (LBP) levels] and acidic mucus were evaluated. Results: HEAL9 administration significantly attenuated cognitive impairment and counteracted colonic dysmotility in SAMP8 mice. Moreover, HEAL9 decreased astrogliosis and microgliosis, Aβ1-42 accumulation and inflammasome activation in colon and brain and normalized plasma LBP levels and colonic acidic mucus content. Conclusion: HEAL9 intake alleviated cognitive decline and normalized colonic motility in the prodromal phases of AD via the modulation of microbiota-gut-inflammasome-brain signalling. Thus, dietary supplementation with HEAL9 could be considered as a suitable therapeutical option for the treatment of AD and related intestinal symptoms in the early stages of the disease.

Molecular insights into P2X signalling cascades in acute kidney injury

Acute kidney injury (AKI) is a critical health issue with high mortality and morbidity rates in hospitalized individuals. The complex pathophysiology and underlying health conditions further complicate AKI management. Growing evidence suggests the pivotal role of ion channels in AKI progression, through promoting tubular cell death and altering immune cell functions. Among these channels, P2X purinergic receptors emerge as key players in AKI pathophysiology. P2X receptors gated by adenosine triphosphate (ATP), exhibit increased extracellular levels of ATP during AKI episodes. More importantly, certain P2X receptor subtypes upon activation exacerbate the situation by promoting the release of extracellular ATP. While therapeutic investigations have primarily focused on P2X4 and P2X7 subtypes in the context of AKI, while understanding about other subtypes still remains limited. Whilst some P2X antagonists show promising results against different types of kidney diseases, their role in managing AKI remains unexplored. Henceforth, understanding the intricate interplay between P2X receptors and AKI is crucial for developing targeted interventions. This review elucidates the functional alterations of all P2X receptors during normal kidney function and AKI, offering insights into their involvement in AKI. Notably, we have highlighted the current knowledge of P2X receptor antagonists and the possibilities to use them against AKI in the future. Furthermore, the review delves into the pathways influenced by activated P2X receptors during AKI, presenting potential targets for future therapeutic interventions against this critical condition.

The pharmacological blockade of P2X4 receptor as a viable approach to manage visceral pain in a rat model of colitis

Nowadays, the pharmacological management of visceral hypersensitivity associated with colitis is ineffective. In this context, targeting purinergic P2X4 receptor (P2X4R), which can modulate visceral pain transmission, could represent a promising therapeutic strategy. Herein, we tested the pain-relieving effect of two novel and selective P2X4R antagonists (NC-2600 and NP-1815-PX) in a murine model of DNBS-induced colitis and investigated the mechanisms underlying their effect. Tested drugs and dexamethasone (DEX) were administered orally, two days after colitis induction. Treatment with tested drugs and DEX improved tissue inflammatory parameters (body weight, spleen weight, macroscopic damage, TNF and IL-1β levels) in DNBS-rats. In addition, NC-2600 and NP-1815-PX attenuated visceral pain better than DEX and prevented the reduction of occludin expression. In in vitro studies, treatment of CaCo2 cells with supernatant from THP-1 cells, previously treated with LPS plus ATP, reduced the expression of tight junctions protein. By contrast, CaCo2 cells treated with supernatant from THP-1 cells, previously incubated with tested drugs, counteracted the reduction of tight junctions due to the inhibition of P2X4R/NLRP3/IL-1β axis. In conclusion, these results suggest that the direct and selective inhibition of P2X4R represents a viable approach for the management of visceral pain associated with colitis via NLRP3/IL-1β axis inhibition.

Methods for studying P2X4 receptor ion channels in immune cells

The P2X4 receptor is a trimeric ligand-gated ion channel activated by adenosine 5'-triphosphate (ATP). P2X4 is present in immune cells with emerging roles in inflammation and immunity, and related disorders. This review aims to provide an overview of the methods commonly used to study P2X4 in immune cells, focusing on those methods used to assess P2RX4 gene expression, the presence of the P2X4 protein, and P2X4 ion channel activity in these cells from humans, dogs, mice and rats. P2RX4 gene expression in immune cells is commonly assessed using semi-quantitative and quantitative reverse-transcriptase-PCR. The presence of P2X4 protein in immune cells is mainly assessed using anti-P2X4 polyclonal antibodies with immunoblotting or immunochemistry, but the use of these antibodies, as well as monoclonal antibodies and nanobodies to detect P2X4 with flow cytometry is increasing. Notably, use of an anti-P2X4 monoclonal antibody and flow cytometry has revealed that P2X4 is present on immune cells with a rank order of expression in eosinophils, then neutrophils and monocytes, then basophils and B cells, and finally T cells. P2X4 ion channel activity has been assessed mainly by Ca2+ flux assays using the cell permeable Ca2+-sensitive dyes Fura-2 and Fluo-4 with fluorescence microscopy, spectrophotometry, or flow cytometry. However, other methods including electrophysiology, and fluorescence assays measuring Na+ flux (using sodium green tetra-acetate) and dye uptake (using YO-PRO-12+) have been applied. Collectively, these methods have demonstrated the presence of functional P2X4 in monocytes and macrophages, microglia, eosinophils, mast cells and CD4+ T cells, with other evidence suggestive of functional P2X4 in dendritic cells, neutrophils, B cells and CD8+ T cells.

Use of Saccharomyces boulardii CNCM I-745 as therapeutic strategy for prevention of nonsteroidal anti-inflammatory drug-induced intestinal injury

BACKGROUND AND PURPOSE

Nonsteroidal anti-inflammatory drugs (NSAIDs) can be associated with severe adverse digestive effects. This study examined the protective effects of the probiotic Saccharomyces boulardii CNCM I-745 in a rat model of diclofenac-induced enteropathy.

EXPERIMENTAL APPROACH

Enteropathy was induced in 40-week-old male rats by intragastric diclofenac (4 mg·kg-1 BID for 14 days). S. boulardii CNCM I-745 (3 g·kg-1 BID by oral gavage) was administered starting 14 days before (preventive protocol) or along with (curative protocol) diclofenac administration. Ileal damage, inflammation, barrier integrity, gut microbiota composition and toll-like receptors (TLRs)-nuclear factor κB (NF-κB) pathway were evaluated.

KEY RESULTS

Diclofenac elicited intestinal damage, along with increments of myeloperoxidase, malondialdehyde, tumour necrosis factor and interleukin-1β, overexpression of TLR2/4, myeloid differentiation primary response 88 (Myd88) and NF-κB p65, increased faecal calprotectin and butyrate levels, and decreased blood haemoglobin levels, occludin and butyrate transporter monocarboxylate transporter 1 (MCT1) expression. In addition, diclofenac provoked a shift of bacterial taxa in both faecal and ileal samples. Treatment with S. boulardii CNCM I-745, in both preventive and curative protocols, counteracted the majority of these deleterious changes. Only preventive administration of the probiotic counteracted NSAID-induced decreased expression of MCT1 and increase in faecal butyrate levels. Occludin expression, after probiotic treatment, did not significantly change.

CONCLUSIONS AND IMPLICATIONS

Treatment with S. boulardii CNCM I-745 prevents diclofenac-induced enteropathy through anti-inflammatory and antioxidant activities. Such effects are likely to be related to increased tissue butyrate bioavailability, through an improvement of butyrate uptake by the enteric mucosa.

Purinergic neurotransmission receptor P2X4 silencing alleviates intracerebral hemorrhage-induced neuroinflammation by blocking the NLRP1/Caspase-1 pathway

This study is performed to explore the role of P2X4 in intracerebral hemorrhage (ICH) and the association between P2X4 and the NLRP1/Caspase-1 pathway. The mouse ICH model was established via collagenase injection into the right basal ganglia. P2X4 expression in brain tissues was knocked down via intracerebroventricular injection with adeno-associated virus (AAV) harboring shRNA against shP2X4. The gene expression of P2X4 and protein levels related to NLRP1 inflammasome were detected using qRT-PCR and Western blot analysis, respectively. Muramyl dipeptide (an activator of NLRP1) was used to activate NLRP1 in brain tissues. ICH induced high expression of P2X4 in mouse brain tissues. The knockdown of P2X4 alleviated short- and long-term neurological deficits of ICH mice, as well as inhibited the tissue expression and serum levels of pro-inflammatory cytokines, including TNF-α, interleukin (IL)-6, and IL-1β. Additionally, the expressions of NLRP1, ASC, and pro-Caspase-1 were down-regulated upon P2X4 silencing. Moreover, neurological impairment and the expression and secretion of cytokines after P2X4 silencing were aggravated by the additional administration of MDP. P2X4 knockdown represses neuroinflammation in brain tissues after ICH. Mechanistically, P2X4 inhibition exerts a neuroprotective effect in ICH by blocking the NLRP1/Caspase-1 pathway.

P2X7-NLRP3-Caspase-1 signaling mediates activity-induced muscle pain in male but not female mice

ABSTRACT

We developed an animal model of activity-induced muscle pain that is dependent on local macrophage activation and release of interleukin-1β (IL-1β). Activation of purinergic type 2X (P2X) 7 receptors recruits the NOD-like receptor protein (NLRP) 3 and activates Caspase-1 to release IL-1β. We hypothesized that pharmacological blockade of P2X7, NLRP3, and Caspase-1 would prevent development of activity-induced muscle pain in vivo and release of IL-1β from macrophages in vitro. The decrease in muscle withdrawal thresholds in male, but not female, mice was prevented by the administration of P2X7, NLRP3, and Caspase-1 inhibitors before induction of the model, whereas blockade of IL-1β before induction prevented muscle hyperalgesia in both male and female mice. Blockade of P2X7, NLRP3, Capsase-1, or IL-1β 24 hours, but not 1 week, after induction of the model alleviated muscle hyperalgesia in male, but not female, mice. mRNA expression of P2X7, NLRP3, Caspase-1, and IL-1β from muscle was increased 24 hours after induction of the model in both male and female mice. Using multiplex, increases in IL-1β induced by combining adenosine triphosphate with pH 6.5 in lipopolysaccharide-primed male and female macrophages were significantly lower with the presence of inhibitors of P2X7 (A740003), NLRP3 (MCC950), and Caspase-1 (Z-WEHD-FMK) when compared with the vehicle. The current data suggest the P2X7/NLRP3/Caspase-1 pathway contributed to activity-induced muscle pain initiation and early maintenance phases in male but not female, and not in late maintenance phases in male mice.

Dietary Supplement, Containing the Dry Extract of Curcumin, Emblica and Cassia, Counteracts Intestinal Inflammation and Enteric Dysmotility Associated with Obesity

Intestinal epithelial barrier (IEB) impairment and enteric inflammation are involved in the onset of obesity and gut-related dysmotility. Dietary supplementation with natural plant extracts represents a useful strategy for the management of body weight gain and systemic inflammation associated with obesity. Here, we evaluate the efficacy of a food supplement containing the dry extract of Curcumin, Emblica and Cassia in counteracting enteric inflammation and motor abnormalities in a mouse model of obesity, induced by a high-fat diet (HFD). Male C57BL/6 mice, fed with standard diet (SD) or HFD, were treated with a natural mixture (Curcumin, Emblica and Cassia). After 8 weeks, body weight, BMI, liver and spleen weight, along with metabolic parameters and colonic motor activity were evaluated. Additionally, plasma LBP, fecal calprotectin, colonic levels of MPO and IL-1β, as well as the expression of occludin, TLR-4, MYD88 and NF-κB were investigated. Plant-based food supplement administration (1) counteracted the increase in body weight, BMI and metabolic parameters, along with a reduction in spleen and liver weight; (2) showed strengthening effects on the IEB integrity; and (3) reduced enteric inflammation and oxidative stress, as well as ameliorated the colonic contractile dysfunctions. Natural mixture administration reduced intestinal inflammation and counteracted the intestinal motor dysfunction associated with obesity.

ATP ion channel P2X purinergic receptors in inflammation response

Different studies have confirmed that P2X purinergic receptors play a key role in inflammation. Activation of P2X purinergic receptors can release inflammatory cytokines and participate in the progression of inflammatory diseases. In an inflammatory microenvironment, cells can release a large amount of ATP to activate P2X receptors, open non-selective cation channels, activate multiple intracellular signaling, release multiple inflammatory cytokines, amplify inflammatory response. While P2X4 and P2X7 receptors play an important role in the process of inflammation. P2X4 receptor can mediate the activation of microglia involved in neuroinflammation, and P2X7 receptor can mediate different inflammatory cells to mediate the progression of tissue-wide inflammation. At present, the role of P2X receptors in inflammatory response has been widely recognized and affirmed. Therefore, in this paper, we discussed the role of P2X receptors-mediated inflammation. Moreover, we also described the effects of some antagonists (such as A-438079, 5-BDBD, A-804598, A-839977, and A-740003) on inflammation relief by antagonizing the activities of P2X receptors.