P2X7 receptor antagonist A-438079 alleviates oxidative stress of lung in LPS-induced septic rats

Alleviation of LPS-induced acute lung injury by propolis-based nanocomposites through the TLR4/NFKB and P2X7/AKT pathways: Randomized-controlled experimental study

Sepsis-associated acute lung injury continues to pose a significant medical challenge with substantial morbidity and mortality rates. In this study, we investigated the therapeutic potential of propolis-based treatments and their nanocomposites in modulating inflammation and apoptosis using a lipopolysaccharide (LPS)-induced rat model of sepsis. Forty-two Sprague-Dawley rats were divided into seven groups (n = 6): control, LPS (5 mg/kg, i.p.), LPS + Propolis (100 mg/kg, i.p.), LPS + NanoPropolis (100 mg/kg, i.p.), LPS + silver nanoparticles propolis (AgNPsPro) (50 mg/kg), and a negative propolis group (100 mg/kg, i.p.). The rats were assessed for inflammatory, oxidative stress, and apoptotic markers through Western blot, histopathological analyses, and biochemical measurements. The LPS group exhibited significantly higher levels of pro-inflammatory cytokines (IL-1β, TNF-α) and the systemic infection marker presepsin (PRSN) in blood, as well as the oxidative stress marker malondialdehyde (MDA) in lung tissue. The treatment groups, particularly LPS + AgNPsPro, showed significant reductions in these markers, with decreased levels of MDA, IL-1β, TNF-α, NF-κB, and TLR4, and increased GSH content in lung tissue (p < 0.05). The anti-apoptotic protein BCL-2 was upregulated, while pro-apoptotic BAX expression was reduced, indicating enhanced cell survival. The P2X7 receptor, a key inflammation regulator, and the AKT signaling pathway, involved in cell survival, were positively modulated by the treatments. Histopathological findings corroborated these results, showing less lung tissue damage. In conclusion, propolis-based treatments, especially in combination with nanoparticles, demonstrate therapeutic potential in reducing inflammation, oxidative stress, and apoptosis in sepsis-induced lung injury.

D-carvone attenuates LPS-induced acute lung injury via TLR4/NF-κB and Nrf2/HO-1 signaling pathways in rats

Acute lung injury (ALI) is a severe respiratory disorder associated with high morbidity and mortality. Lipopolysaccharide (LPS) is widely used to induce ALI in animal models. D-carvone, a natural monoterpene, has been reported to possess anti-inflammatory and antioxidant properties. This study aimed to investigate the protective effects of D-carvone on LPS-induced ALI in rats. Thirty-six male rats were randomly divided into six groups (n = 6): control, D-carvone (10 mg/kg and 20 mg/kg p.o.), LPS (10 mg/kg E. coli lipopolysaccharide i.p.), and LPS + D-carvone (LPS with either 10 or 20 mg/kg D-carvone). D-carvone was administered orally once daily for 10 days. On day 10, sepsis was induced with LPS administration, and samples were collected after 6 h under deep anesthesia. LPS administration caused significant lung injury, as evidenced by increased histopathological scores, upregulation of pro-inflammatory markers (TLR4, IL-1β, TNF-α), and oxidative stress (increased MDA, decreased GSH and SOD). Treatment with D-carvone at both doses significantly attenuated these changes. D-carvone downregulated pro-inflammatory markers, upregulated anti-inflammatory (NRF2) and anti-apoptotic (Bcl-2) proteins, and reduced the levels of pro-inflammatory cytokines (IL-1β, TNF-α, IL-8) in lung tissues. In conclusion, D-carvone protects against LPS-induced ALI in rats, possibly through its anti-inflammatory and antioxidant properties. These findings suggest that D-carvone could be a potential therapeutic candidate for preventing and treating ALI.

Astaxanthin Alleviates Lung Injury by Regulating Oxidative Stress, Inflammatory Response, P2X7 Receptor, NF-κB, Bcl-2, and Caspase-3 in LPS-Induced Endotoxemia

Sepsis remains the leading cause of multiple-organ injury due to endotoxemia. Astaxanthin (ASTA), widely used in marine aquaculture, has an extraordinary potential for antioxidant and anti-inflammatory activity. Purinergic receptor (e.g., P2X7R) activation is a powerful signaling in the modulation of inflammation. The effect of ASTA was investigated on the regulation of oxidative stress, inflammatory response, apoptotic mediators, and P2X7R expression in the lung injury during lipopolysaccharide (LPS)-induced endotoxemia. Twenty-four rats were blocked into four groups as Control, LPS, ASTA, and LPS + ASTA. LPS was administered by intraperitoneal injection and ASTA by gavage. Blood and lung samples were taken 6 h after the administrations. The methods were ELISA, western blotting, histopathology, and immunohistochemistry. Sepsis was confirmed by the elevations of IL-1β, IL-6, IL-10, and TNF-α levels in bloodstream. Lung injury was determined by histopathological changes. There were increased P2X7R expression, malondialdehyde (MDA), IL-1β, TNF-α, nuclear factor kappa B (NF-κB), and Caspase-3 and decreased B-cell lymphoma 2 (Bcl-2) and glutathione (GSH) in the septic lung tissue (p < 0.05). ASTA treatment improved MDA, GSH, IL-1β, TNF-α, P2X7R, NF-κB, Caspase-3, and Bcl-2 levels and reduced P2X7R immunoreactivity and histological abnormalities in the lung (p < 0.05). The production of pro-inflammatory cytokines, oxidative stress, P2X7R expression, and apoptotic mediators in the lung is associated with LPS-induced endotoxemia. The ASTA administration appears to regulate the expressions of P2X7R, NF-κB, Bcl-2, and Caspase-3 improving the antioxidative and anti-inflammatory response of the lung tissue in sepsis, in vivo.

Lipopolysaccharide-Neutralizing Peptide Modulates P2X7 Receptor-Mediated Interleukin-1β Release

Lipopolysaccharide (LPS)-neutralizing peptides are emerging as new potential therapeutic modalities to treat sepsis and skin infections. Purinergic ligand-gated ion channels (P2X receptors) play a critical role in various biological processes, including inflammation. Recent drug development efforts have significantly focused on the modulation of P2X receptors. Here, we investigated the effects of the synthetic LPS-neutralizing peptide Pep19-2.5 on human P2X receptors in cells of the innate immune system. Pep19-2.5 concentration-dependently triggered Ca2+ influx, interleukin (IL)-1β, and lactate dehydrogenase (LDH) release in Toll-like receptor-stimulated human macrophages and monocytes. Ca2+ influx was mediated at least partially by P2X7 receptors, and IL-1β and LDH release by P2X7 receptors, respectively. Confocal microscopy confirmed the colocalization of Pep19-2.5 with P2X7 receptors. Pep19-2.5-induced IL-1β release in primed cells was dependent on K+ efflux, caspase-1, and the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing protein 3 inflammasome. In the presence of the P2X7 receptor agonist 2'(3')-O-(4-benzoylbenzoyl)adenosine-5'-triphosphate, Pep19-2.5 reduced IL-1β and LDH release. In 1321N1, astrocytoma cells stably transfected with human P2X receptors, Pep19-2.5 potently modulated P2X7 and P2X4 receptors (IC50 values of 0.346 and 0.146 μM, respectively) but showed less (P2X1, P2X3) or no activity (P2X2) at other P2X receptor subtypes. Our findings underline the potential of LPS-neutralizing peptides as modulators of P2X receptors, thus expanding their applicability beyond the treatment of sepsis to the treatment of inflammatory diseases.

Could P2X7 receptor be a potencial target in neonatal sepsis?

The United Nations Inter-Agency Group for Child Mortality Estimation (UNIGME) estimates that every year 2.5 million neonates die in their first month of life, accounting for nearly one-half of deaths in children under 5 years of age. Neonatal sepsis is the third leading cause of neonatal mortality. The worldwide burden of bacterial sepsis is expected to increase in the next decades due to the lack of effective molecular therapies to replace the administration of antibiotics whose efficacy is compromised by the emergence of resistant strains. In addition, prolonged exposure to antibiotics can have negative effects by increasing the risk of infection by other organisms. With the global burden of sepsis increasing and no vaccine nor other therapeutic approaches proved efficient, the World Health Organization (WHO) stresses the need for new therapeutic targets for sepsis treatment and infection prevention (WHO, A73/32). In response to this unresolved clinical issue, the P2X7 receptor (P2X7R), a key component of the inflammatory cascade, has emerged as a potential target for treating inflammatory/infection diseases. Indeed numerous studies have demonstrated the relevance of the purinergic system as a pharmacological target in addressing immune-mediated inflammatory diseases by regulating immunity, inflammation, and organ function. In this review, we analyze key features of sepsis immunopathophysiology focusing in neonatal sepsis and on how the immunomodulatory role of P2X7R could be a potential pharmacological target for reducing the burden of neonatal sepsis.

Silver Nanoparticles Loaded With Oleuropein Alleviates LPS-Induced Acute Lung Injury by Modulating the TLR4/P2X7 Receptor-Mediated Inflammation and Apoptosis in Rats

Toll-like receptor 4 (TLR-4) ligands were initially shown to be the source of lipopolysaccharide (LPS), a gram-negative bacterium's cell wall immunostimulatory component. Oxidative stress, apoptosis, and inflammation are all potential effects of LPS treatment on the lungs. By triggering oxidative stress and inflammation, these negative effects could be avoided. Robust flavonoid oleuropein (OLE) exhibits anti-inflammatory, antiproliferative, and antioxidative properties. A nanodelivery system could improve its low bioavailability, making it more effective and useful in treating chronic human ailments. This study evaluates the effects of AgNP-loaded OLE on LPS-induced lung injury in rats in terms of TLR4/P2X7 receptor-mediated inflammation and apoptosis. Forty-eight male albino rats were randomly divided into eight groups. Drugs were administered to the groups in the doses specified as follows: Control, LPS (8 mg/kg ip), OLE (50 mg/kg) AgNPs (100 mg/kg), OLE + AgNPs (50 mg/kg), LPS + OLE (oleuropein 50 mg/kg ig + LPS 8 mg/kg ip), LPS + AgNPs (AgNPs 100 mg/kg ig + LPS 8 mg/kg ip), and LPS + OLE + AgNPs (OLE + AgNPs 50 mg/kg + LPS 8 mg/kg ip). After the applications, the rats were decapitated under appropriate conditions, and lung tissues were obtained. Oxidative stress (SOD, MDA, and GSH), and inflammation (IL-6, IL-1β, TNF-α, Nrf2, P2X7R, AKT, and TLR4) parameters were evaluated in the obtained lung tissues. Additionally, histopathology studies were performed on lung tissue samples. The data obtained were evaluated by comparison between groups. Both OLE and OLE + AgNPs showed potential in reducing oxidative stress, inflammation, and apoptosis (p < 0.05). These findings were supported by histopathological analysis, which revealed that tissue damage was reduced in OLE and OLE + AgNPs-treated groups. According to the results, LPS-induced lung injury can be reduced by using nanotechnology and producing OLE + AgNP.

The impact of the P2X7 receptor on the tumor immune microenvironment and its effects on tumor progression

Cancer is a significant global health concern, and finding effective methods to treat it has been a focus of scientific research. It has been discovered that the growth, invasion, and metastasis of tumors are closely related to the environment in which they exist, known as the tumor microenvironment (TME). The immune response interacting with the tumor occurring within the TME constitutes the tumor immune microenvironment, and the immune response can lead to anti-tumor and pro-tumor outcomes and has shown tremendous potential in immunotherapy. A channel called the P2X7 receptor (P2X7R) has been identified within the TME. It is an ion channel present in various immune cells and tumor cells, and its activation can lead to inflammation, immune responses, angiogenesis, immunogenic cell death, and promotion of tumor development. This article provides an overview of the structure, function, and pharmacological characteristics of P2X7R. We described the concept and components of tumor immune microenvironment and the influence immune components has on tumors. We also outlined the impact of P2X7R regulation and how it affects the development of tumors and summarized the effects of drugs targeting P2X7R on tumor progression, both past and current, assisting researchers in treating tumors using P2X7R as a target.

P2X7 receptor: A receptor closely linked with sepsis-associated encephalopathy

Sepsis is defined as a dysregulated host response to infection resulting in life-threatening organ dysfunction. Sepsis-associated encephalopathy (SAE) is the main manifestation of sepsis. Inflammation, peroxidation stress injury, and apoptosis are the main factors involved in the pathogenesis of SAE. A growing body of evidence has proved that P2X7 receptor (P2X7R), a cationic channel receptor that is widely distributed in the body, plays a major role in the occurrence and development of inflammatory injury. Therefore, this review mainly describes the activation of P2X7R in sepsis, which leads to the recruitment of inflammatory cells to the cerebral vasculature, the destruction of the blood-brain barrier, the activation of microglial cells in the brain, the apoptosis of brain cells, and other damage processes. This review also illustrates the potential therapeutic value of P2X7R inhibition in SAE.

Inflammasome modulation with P2X7 inhibitor A438079-loaded dressings for diabetic wound healing

The inflammasome is a multiprotein complex critical for the innate immune response to injury. Inflammasome activation initiates healthy wound healing, but comorbidities with poor healing, including diabetes, exhibit pathologic, sustained activation with delayed resolution that prevents healing progression. In prior work, we reported the allosteric P2X7 antagonist A438079 inhibits extracellular ATP-evoked NLRP3 signaling by preventing ion flux, mitochondrial reactive oxygen species generation, NLRP3 assembly, mature IL-1β release, and pyroptosis. However, the short half-life in vivo limits clinical translation of this promising molecule. Here, we develop a controlled release scaffold to deliver A438079 as an inflammasome-modulating wound dressing for applications in poorly healing wounds. We fabricated and characterized tunable thickness, long-lasting silk fibroin dressings and evaluated A438079 loading and release kinetics. We characterized A438079-loaded silk dressings in vitro by measuring IL-1β release and inflammasome assembly by perinuclear ASC speck formation. We further evaluated the performance of A438079-loaded silk dressings in a full-thickness model of wound healing in genetically diabetic mice and observed acceleration of wound closure by 10 days post-wounding with reduced levels of IL-1β at the wound edge. This work provides a proof-of-principle for translating pharmacologic inhibition of ATP-induced inflammation in diabetic wounds and represents a novel approach to therapeutically targeting a dysregulated mechanism in diabetic wound impairment.

Blockade of P2X7 receptor-mediated purinergic signaling with A438079 protects against LPS-induced liver injury in rats

The study aimed to investigate the hepatoprotective effects of purinergic receptor (P2X7R) antagonism by A438079 in liver damage. An experimental model of inflammation was performed by intraperitoneal (i.p.) lipopolysaccharide (LPS) administration in the rat. The groups were Control, A438079, dimethyl sulfoxide (DMSO), LPS, LPS + DMSO, and LPS + A438079. Following LPS (8 mg/kg) injection, A438079 (15 mg/kg) and DMSO (0.1 mL) were administrated (i.p) in the study groups. The blood and the liver tissues were removed for histological, biochemical, and western blot analyses. In the biochemical analysis, serum aspartate transaminase (AST) and alanine transaminase (ALT) concentrations, the tissue glutathione (GSH) level, and superoxide dismutase (SOD) activity dramatically decreased and malondialdehyde (MDA) level increased in the LPS and LPS + DMSO groups compared to the LPS + A438079 group. In the histological analysis, severe sinusoidal dilatation, necrotic hepatocytes, and inflammatory cell infiltration were observed in the LPS and LPS + DMSO groups while these effects were lessened in the LPS + A438079 group. The relative protein expression levels of P2X7R, Nf-kB-p65, IL-6, and Caspase-3 were significantly higher in the LPS and the LPS + DMSO groups than in the LPS + A438079 group. On the other hand, these protein expressions were considerably lower in the Control, A438079, and DMSO groups compared to the LPS + A438079 group. In addition, Bcl-2 protein expression was significantly lower in the LPS and the LPS + DMSO groups and higher in the LPS + A438079 group compared to the other groups. The protective effect of A438079 against LPS-induced hepatic inflammation may be related to P2X7R antagonism, inflammatory mediators, and apoptotic cell death.