The P2X7 Receptor in Infection and Inflammation

The (neuro)inflammatory system in anxiety disorders and PTSD: Potential treatment targets

Targeting the immune system has recently garnered attention in the treatment of stress- associated psychiatric disorders resistant to existing pharmacotherapeutics. While such approaches have been studied in considerable detail in depression, the role of (neuro)inflammation in anxiety-related disorders, or in anxiety as an important transdiagnostic symptom, is much less clear. In this review we first critically review clinical and in part preclinical evidence of central and peripheral immune dysregulation in anxiety disorders and post-traumatic stress disorder (PTSD) and briefly discuss proposed mechanisms of how inflammation can affect anxiety-related symptoms. We then give an overview of existing and potential future targets in inflammation-associated signal transduction pathways and discuss effects of different immune-modulatory drugs in anxiety-related disorders. Finally, we discuss key gaps in current clinical trials such as the lack of prospective studies involving anxiety patient stratification strategies based on inflammatory biomarkers. Overall, although evidence is rather limited so far, there is data to indicate that increased (neuro)inflammation is present in subgroups of anxiety disorder patients. Although exact identification of such immune subtypes of anxiety disorders and PTSD is still challenging, these patients will likely particularly benefit from therapeutic targeting of aspects of the inflammatory system. Different anti-inflammatory treatment approaches (microglia-directed treatments, pro-inflammatory cytokine inhibitors, COX-inhibitors, phytochemicals and a number of novel anti-inflammatory agents) have indeed shown some efficacy even in non-stratified anxiety patient groups and appear promising as novel alternative or complimentary therapeutic options in specific ("inflammatory") subtypes of anxiety disorder and PTSD patients.

EZH2-mediated suppression of TIMP1 in spinal GABAergic interneurons drives microglial activation via MMP-9-TLR2/4-NLRP3 signaling in neuropathic pain

Effective management of neuropathic pain remains a significant challenge due to the limited understanding of its underlying mechanisms. We found that the FDA-approved enhancer of zeste homolog 2 (EZH2) inhibitor, EPZ6438, can prevent the development of neuropathic pain caused by chronic constriction injury (CCI). Therefore, we utilized EPZ6438 as a probe to investigate the molecular events involved in the early stage of neuropathic pain. RNA-seq analysis reveals that EPZ6438 significantly upregulates Timp1 transcription in the spinal cord of mice. As a specific endogenous inhibitor of MMP-9, tissue inhibitor of metalloproteinase 1 (TIMP1) levels significantly decrease in the cerebrospinal fluid of both neuropathic pain patients and the CCI rat models. Importantly, intrathecal administration of mouse recombinant TIMP1 protein (rmTIMP1) reverses CCI-induced mechanical and thermal hyperalgesia. Mechanistically, substance P released from primary sensory neurons suppresses TIMP1 in spinal GABAergic interneurons by elevating EZH2 expression, which enhances H3K27me3 enrichment at the Timp1 promoter. Blocking spinal NK1R effectively prevents the downregulation of TIMP1 and alleviates CCI-induced hyperalgesia. The imbalance between TIMP1 and MMP-9 leads to NLRP3 activation in spinal microglia and increases IL-1β maturation via TLR2/4 pathway. TIMP1 injection eliminates MMP-9-induced NLRP3 activation and blocks hyperalgesia, suggesting that TIMP1 is a critical gatekeeper in preventing neuroinflammation during neuropathic pain development.

Regulation of BzATP-Induced Blood-Brain Barrier Endothelial Cell Hyperpermeability by NLRP3 Inflammasome Inhibition

OBJECTIVE

The blood-brain barrier (BBB) is a semi-permeable microvascular barrier, composed of endothelial cells conjoined by tight junction proteins. Following pathological conditions, i.e., traumatic brain injury (TBI), BBB dysfunction occurs, leading to microvascular hyperpermeability, resulting in cerebral edema formation and elevated intracranial pressure. Recent evidence suggests that the activation of pro-inflammatory signaling pathways is critical to BBB dysfunction. The NLRP3 inflammasome has been implicated as a key component of pro-inflammatory signaling. The aim of this study was to determine the upstream regulators of NLRP3 inflammasome activation that cause subsequent BBB aberration and microvascular hyperpermeability.

METHODS

Brain microvascular endothelial cells were exposed to benzoyl ATP (BzATP) with or without MCC950. We employed immunocytochemical localization of tight junction proteins, fluorometric enzymatic assays, total gene expression analyses of ZO-1, and monolayer permeability studies to assess the effect of BzATP-induced injury on NLRP3 inflammasome activation/inhibition.

RESULTS

BzATP treatment induced monolayer hyperpermeability and increased caspase-1 and MMP-9 activities. NLRP3 inhibition decreased caspase-1 and MMP-9 activities and rescued BzATP-induced monolayer permeability significantly.

CONCLUSIONS

NLRP3 inflammasome signaling is critical to BBB endothelial cell dysfunction. Extracellular ATP is an upstream promoter of BBB hyperpermeability. NLRP3 inflammasome activation leads to subsequent caspase-1 and MMP-9-mediated tight junction protein disarray.

Adenosine triphosphate-mediated signaling of P2X7 receptors controls donor extracellular vesicle release and major histocompatibility complex cross-decoration after allotransplantation

After skin allotransplantation, intercellular transfer of donor major histocompatibility complex molecules mediated primarily by extracellular vesicles (EVs) released by the allograft is known to contribute to semidirect and indirect activation of alloreactive T cells involved in graft rejection. At the same time, there is ample evidence showing that initiation of adaptive alloimmunity depends on early innate inflammation caused by tissue injury and subsequent activation of myeloid cells (macrophages and dendritic cells) recognizing danger-associated molecular patterns. Among these danger-associated molecular patterns, extracellular adenosine triphosphate plays a key role in innate inflammation by binding to P2X7 receptors (P2X7Rs). Indeed, this process leads to the activation of the Nod-like receptor protein 3 inflammasome and the subsequent production and release of inflammatory cytokines and EVs. This prompted us to evaluate the influence of innate inflammation triggered by adenosine triphosphate-mediated signaling of P2X7Rs on EV release by donor cells after skin transplantation in mice. In this article, we show that inhibition of P2X7R signaling suppresses both EV release and major histocompatibility complex cross-decoration of leukocytes and prolongs skin allograft survival in mice. This study reveals a novel aspect of the role of innate immunity in allotransplantation.

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.

ATP-Gated P2X7-Ion Channel on Kidney-Resident Natural Killer T Cells and Memory T Cells in Intrarenal Inflammation

Key Points

Parenchymal T cells in the kidney expressed much higher levels of P2X7 than vascular T cells. P2X7-blocking nanobodies uncover a large fraction of kidney-resident natural killer T and tissue-resident memory T cells. These cells were lost during cell preparation because of activation of P2X7 by NAD+ released from damaged cells, unless blocked by nanobodies.

Background

The P2X7 ion channel, a key sensor of sterile inflammation, has been implicated as a therapeutic target in GN, and P2X7-antagonistic nanobodies can attenuate experimental GN. However, little is known about the expression of P2X7 on renal immune cells.

Methods

We used conventional immunofluorescence of kidney sections and intraperitoneal injection of nanobodies in mice followed by flow cytometry analysis of parenchymal T cells and RNA sequencing to elucidate the expression and function of P2X7 on parenchymal and vascular immune cells in the mouse kidney.

Results

Our study showed that parenchymal T cells, including a large subset of natural killer T cells and CD69+ tissue-resident memory T cells, display much higher cell surface levels of P2X7 than vascular T cells. After a single intraperitoneal injection of P2X7-blocking nanobodies, P2X7 on parenchymal T cells was fully occupied by the injected nanobodies within 30 minutes. This resulted in an effective protection of these cells from nicotinamide adenine dinucleotide–induced cell death during cell preparation. Conversely, systemic injection of nicotinamide adenine dinucleotide that mimics sterile inflammation results in the selective depletion of P2X7hiCD69hi T cells from the kidney parenchyma.

Conclusions

Our study uncovered a novel purinergic regulatory mechanism affecting kidney-resident T-cell populations.

3-(3-(diethylamino)propyl)-2-(4-(methylthio)phenyl)thiazolidin-4-one Attenuates Scopolamine-induced Cognitive Impairment in Rats: Insights Into Neuroprotective Effects

Alzheimer's Disease (AD) is characterized by memory decline, dysregulation in cholinergic and purinergic signaling, neuroinflammation, and oxidative stress. Current treatments are limited, highlighting the need for new compounds to prevent or delay AD progression. Thiazolidinones have emerged as promising candidates due to their antioxidant, anti-inflammatory, and anticholinesterase properties. The aim of this study was to evaluate the effects of 3-(3-(diethylamino)propyl)-2-(4-(methylthio)phenyl)thiazolidin-4-one (DS27) in a rat model of scopolamine-induced memory deficits. Male rats were divided into groups: I - Control, II - Scopolamine (SCO) (1 mg/kg), III - SCO and DS27 (5 mg/kg), IV - SCO and DS27 (10 mg/kg), V - SCO and donepezil (5 mg/kg). The animals were treated orally with DS27 or donepezil for seven days. On the 8th day, they underwent the open field test and inhibitory avoidance training, followed by intraperitoneal administration SCO. Twenty-four hours later, an inhibitory avoidance test was conducted. Acetylcholinesterase (AChE) activity, oxidative stress, and inflammatory and purinergic parameters were analyzed in the cerebral cortex, hippocampus, cerebrospinal fluid, serum, lymphocytes, and liver. DS27 prevented memory deficits, alterations in AChE activity, and oxidative damage induced by SCO in brain structures. Additionally, DS27 prevented SCO-induced decrease in IL-10 levels, and increase in IL-6, and TNF-α expression in the cerebral cortex, and normalized ATP and ADP hydrolysis in cerebrospinal fluid and lymphocytes. DS27 did not induce oxidative stress in the liver or alter serum biochemical parameters. These findings suggest that DS27 has significant neuroprotective properties and could be a promising alternative for treating neurodegenerative diseases like AD.

Inflammatory pain and electroacupuncture: how the P2X3 receptor can help modulate inflammation-a review of current literature

AIM

Inflammatory pain arises from tissue stress or injury and is initiated by signaling molecules that stimulate the immune and nervous systems. Evidence suggests that purinergic signaling pathways can modulate pain and inflammation through the activation of P1 and P2 purinergic receptors, such as the P2X3 receptor, which are stimulated by extracellular molecules like adenosine triphosphate (ATP). Electroacupuncture (EA) exhibits precise mechanisms that modulate inflammatory pain through the activation of the P2X3 receptor.

OBJECTIVE

This review analyzed evidence regarding the role of electroacupuncture and the purinergic system, particularly the P2X3 receptor, in modulating inflammation and pain.

MATERIALS AND METHODS

A search for the most relevant articles available in the SciVerse Scopus and MEDLINE/PubMed databases was conducted for publications from 1995 to 2024. Articles were initially selected by reading the title, abstract, and main text, respectively.

RESULTS

It was found that the P2X3 receptor, as well as the molecules activating purinergic receptors, such as ATP and adenosine, have the potential to regulate pain and inflammation. Additionally, EA can modulate the purinergic system in an anti-inflammatory response. EA may stimulate analgesia mainly through the conversion of ATP to adenosine, a crucial molecule in pain control.

CONCLUSION

The purinergic system directly influences inflammatory pain and controls inflammation. In this context, EA has the potential to orchestrate this system to control pain and inflammation.

Repeated administration of a subanesthetic dose of ketamine results in impaired motor and cognitive behavior and differential expression of hippocampal P2X1 and P2X7 receptors in adult mice

Ketamine hydrochloride serves multiple purposes, including its use as a general anesthetic, treatment for depression, and recreational drug. In studies involving rodents, ketamine is utilized as a model for schizophrenia. However, it is unclear whether age affects the behavioral response induced by repeated ketamine administration and if it modifies the expression levels of N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and purinergic receptors (P2X1, P2X4, P2X7). In the present study, we evaluated the effect of intraperitoneal administration of subanesthetic ketamine dose (30 mg/Kg) for fourteen days on young (35 days of age) and adult (76 days of age) mice on different behavioral tests. Nest-building behavior was evaluated during the fourteen-day treatment; short-term memory and social interaction tests were assessed twenty-four hours after the last administration of ketamine. Interestingly, only adult mice treated with ketamine showed impaired nest-building and novel object recognition. In the hippocampus, an area related to memory and cognition, ketamine administration showed no changes in the relative expression of GluN1, P2X4, and P2X7 while increasing GluA2 and P2X1 only in young mice. In contrast, when assessing the protein levels of P2X1 and P2X7 in the hippocampus following ketamine treatment, young mice exhibited a decrease in P2X1 levels while P2X7 levels increased. In contrast, adult mice showed the opposite pattern; P2X1 levels were higher, and P2X7 levels decreased. These results suggest that adult mice are more vulnerable to repeated ketamine administration than young mice and that a differential response of P2X1 and P2X7 might contribute to ketamine-induced behavioral changes.

Electroacupuncture reduces microglial pyroptosis via P2X7R/NLRP3 axis in the rat model of asphyxial cardiac arrest and cardiopulmonary resuscitation

Asphyxial cardiac arrest and cardiopulmonary resuscitation (ACA/CPR) can severely damage the brain, but electroacupuncture may help reduce this damage through its anti-inflammatory effects. This study explored whether EA could mitigate microglial pyroptosis via the P2X7R/NLRP3 pathway in a rat ACA/CPR model, given that P2X7R activates the NLRP3 inflammasome, leading to pyroptosis and the release of inflammatory factors. Rats underwent an 8-minute ACA/CPR model, with EA stimulation at Baihui (GV 20), Shuigou (DU 26), and bilateral Neiguan (PC 6) every 12 h for three days. P2X7R was modulated using the inhibitor AZ10606120 and the agonist BzATP. Protein expression changes were analyzed using western blotting, ELISA, flow cytometry, and immunofluorescence. ACA/CPR outcomes assessed included survival rate, neurological deficits, brain injury serum markers, and hippocampal ATP levels. The data indicated that microglia activation and co-localization with P2X7R/GSDMD occurred in the hippocampus of the ACA/CPR model, while EA reduced pyroptosis and P2X7R expression 24 h after the restoration of spontaneous circulation (ROSC). In the primary microglial oxygen and glucose deprivation-reoxygenation (OGD/R) model, P2X7R expression increased and then gradually decreased as reoxygenation time progressed. P2X7R and GSDMD levels were high 6 h post-reoxygenation, but AZ10606120 reduced their expression. BzATP counteracted EA's suppression of P2X7R, NLRP3, caspase-1, cleaved caspase-1, GSDMD-FL, and GSDMD-N. Comparable assessments were conducted within the ACA/CPR + AZ10606120 and ACA/CPR cohorts. Consequently, it was deduced that EA exerts a neuroprotective effect following ACA/CPR by modulating P2X7R expression and suppressing microglial pyroptosis.

Focus on P2X7R in microglia: its mechanism of action and therapeutic prospects in various neuropathic pain models

Neuropathic pain (NP) is a common symptom of many diseases and is caused by direct or indirect damage to the nervous system. Tricyclic antidepressants and serotonin-norepinephrine reuptake inhibitors are typical drugs used in clinical practice to suppress pain. However, these drugs have drawbacks, including a short duration of action, a limited analgesic effect, and possible dependence and side effects. Therefore, developing more effective NP treatment strategies has become a priority in medical research and has attracted much research attention. P2X7 receptor (P2X7R) is a non-selective cation channel activated by adenosine triphosphate and is mainly expressed in microglia in the central nervous system. Microglial P2X7R plays an important role in pain regulation, suggesting that it could be a potential target for drug development. This review comprehensively and objectively discussed the latest research progress of P2X7R, including its structural characteristics, functional properties, relationship with microglial activation and polarization, mechanism of action, and potential therapeutic strategies in multiple NP models. This study aimed to provide in-depth insights into the association between P2X7R and NP and explore the mechanism of action of P2X7R in the pathological process of NP and the translational potential and clinical application prospects of P2X7R antagonists in pain treatment, providing a scientific basis for the precise treatment of NP.

Role of Pannexin 1, P2X7, and CFTR in ATP Release and Autocrine Signaling by Principal Cells of the Epididymis

Extracellular adenosine triphosphate (ATP) is a signaling molecule that acts as a paracrine and autocrine modulator of cell function. Here, we characterized the role of luminal ATP in the regulation of epithelial principal cells (PCs) in the epididymis, an understudied organ that plays crucial roles in male reproduction. We previously showed that ATP secretion by PCs is part of a complex communication system that ensures the establishment of an optimal luminal acidic environment in the epididymis. However, the molecular mechanisms regulating ATP release and the role of ATP-mediated signaling in PCs acidifying functions are not fully understood. In other cell types, pannexin 1 (PANX-1) has been associated with ATP-induced ATP release through the interaction with the purinergic P2X7 receptor. Here, we show that PANX-1 and P2X7 are located in the apical membrane of PCs in the mouse epididymis. Functional analysis using the immortalized epididymal PC cell line (DC2) and the mouse epididymis perfused in vivo showed that (1) PANX-1 and P2X7 participate in ATP release by DC2 cells, together with cystic fibrosis transmembrane conductance regulator (CFTR); (2) several ATP-activated P2Y and P2X purinergic receptors are expressed in DC2 cells; (3) the nonhydrolyzable ATP analog ATPγS induces a dose-dependent increase in intracellular Ca2+ concentration in DC2 cells, a process that is mainly mediated by P2X7; and (4) perfusion of the epididymal lumen in vivo with ATPγS induces the internalization of apical sodium-hydrogen exchanger 3 (NHE3) in PCs. Altogether, this study shows that luminal ATP, regulated by CFTR, PANX-1, and P2X7, modulates sodium-proton exchange in PCs in an autocrine manner through activation of purinergic receptor-mediated intracellular calcium signaling.

Identification of Cytochrome P450 2E1 as a Novel Target in Neuroinflammation and Development of Its Inhibitor Q11 as a Treatment Strategy

Neuroinflammation is implicated in nearly all pathological processes of central nervous system (CNS) diseases. However, no medications specifically targeting neuroinflammation are clinically available, and conventional anti-inflammatory drugs exhibit limited efficacy. Here, we identified cytochrome P450 2E1 (CYP2E1) as a novel therapeutic target in neuroinflammation. Elevated CYP2E1 levels were observed in hippocampal tissues of mouse and rat neuroinflammation models, as well as in LPS-stimulated primary microglia. Genetic ablation of Cyp2e1 improved spatial learning and memory in neuroinflammatory rats and reduced pro-inflammatory cytokine levels in Cyp2e1-deficient microglia. Furthermore, Q11 (1-(4-methyl-5-thiazolyl) ethenone), a novel CYP2E1 inhibitor developed and synthesized in our laboratory, effectively ameliorated Alzheimer's disease-related spatial learning and memory functions and depression-related anxiety-like behaviors in mice/rats. Mechanistically, Q11 attenuated microglial activation, neuronal damage, oxidative stress, and neuroinflammation by suppressing the PI3K/Akt, STAT1/3, and NF-κB signaling pathways. These findings establish CYP2E1 as a druggable target for neuroinflammation and propose Q11 as a promising candidate for treating neuroinflammation-related diseases.

Cyclic N, O-acetals and corresponding opened N, N-aminals as new scaffolds with promising anti-inflammatory and antifungal activities against Candida albicans

P2 × 7R is crucial in the pathogenesis of chronic inflammatory diseases, and its activation leads to the release of pro-inflammatory cytokines, exacerbating the inflammatory response. Two new series of scarce cyclic N, O-acetals (ATF 61-74) and corresponding opened N, N-aminals (CS 1-14) have been designed as novel potential P2RX7 antagonists, then synthesized and evaluated for their anti-inflammatory properties through investigating the pro-inflammatory markers and also for their antifungal activity against Candida albicans. Three compounds (ATF 64, CS 8, and CS 9) exhibited dual antifungal and anti-inflammatory properties. ATF 64, CS 8, and CS 9 reduced ROS production and IL-1β expression in macrophages and intestinal cells in a manner correlated with NF-KB expression. These compounds showed excellent antifungal activity against clinical isolates of C. albicans resistant to fluconazole and caspofungin, and reduced C. albicans biofilm formation. Treatment with CS 8 or CS 9 protected the nematode Caenorhabditis elegans against infection with C. albicans and enhanced antimicrobial gene expression. This duality of action offers a promising new pharmacological strategy to counteract inflammatory diseases and propels N, N-aminals as promising candidates for future optimization and investigation.

cGAMP promotes inner blood-retinal barrier breakdown through P2RX7-mediated transportation into microglia

BACKGROUND

Impairment of the inner blood-retinal barrier (iBRB) leads to various blinding diseases including diabetic retinopathy (DR). The cGAS-STING pathway has emerged as a driving force of cardiovascular destruction, but its impact on the neurovascular system is unclear. Here, we show that cGAMP, the endogenous STING agonist, causes iBRB breakdown and retinal degeneration thorough P2RX7-mediated transport into microglia.

METHODS

Extracellular cGAMP and STING pathway were determined in tissue samples from patients with proliferative DR (PDR) and db/db diabetic mice. Histological, molecular, bioinformatic and behavioral analysis accessed effects of cGAMP on iBRB. Single-cell RNA sequencing identified the primary retinal cell type responsive to cGAMP. Specific inhibitors and P2RX7-deficienct mice were used to evaluate P2RX7' role as a cGAMP transporter. The therapeutic effects of P2RX7 inhibitor were tested in db/db mice.

RESULTS

cGAMP was detected in the aqueous humor of patients with PDR and elevated in the vitreous humor with STING activation in db/db mouse retinas. cGAMP administration led to STING-dependent iBRB breakdown and neuron degeneration. Microglia were the primary cells responding to cGAMP, essential for cGAMP-induced iBRB breakdown and visual impairment. The ATP-gated P2RX7 transporter was required for cGAMP import and STING activation in retinal microglia. Contrary to previous thought that mouse P2RX7 nonselectively transports cGAMP only at extremely high ATP concentrations, human P2RX7 directly binds to cGAMP and activates STING under physiological conditions. Clinically, cGAMP-induced microglial signature was recapitulated in fibrovascular membranes from patients with PDR, with P2RX7 being predominantly expressed in microglia. Inhibiting P2RX7 reduced cGAMP-STING activation, protected iBRB and improved neuron survival in diabetic mouse retinas.

CONCLUSIONS

Our study reveals a mechanism for cGAMP-mediated iBRB breakdown and suggests that targeting microglia and P2RX7 may mitigate the deleterious effects of STING activation in retinal diseases linked to iBRB impairment.

Implications of nociceptor receptors and immune modulation: emerging therapeutic targets for autoimmune diseases

Chronic painful autoimmune disorders such as multiple sclerosis (MS), inflammatory bowel disease (IBD), and rheumatoid arthritis (RA) induce significant discomfort. They are defined by persistent inflammation and immune-mediated tissue injury. The activation and sensitisation of nociceptors, mutated in various disorders, are fundamental components contributing to the pain experienced in these conditions. Recent discoveries indicate that immunological mediators and nociceptive receptors interact functionally within peripheral and central sensitisation pathways, amplifying chronic pain. This research examines the involvement of nociceptors in rheumatoid arthritis, multiple sclerosis, and inflammatory bowel disease. It explores how immune cells and pro-inflammatory cytokines induce, sensitise and regulate various nociceptive receptors (P2X, TRPA1 and TRPV1). Finally, we address possible future directions with respect to the treatment of long-lasting effects on immunity, and what new drug targets could be pursued as well, in order to counteract such either neuro-immune interactions in conditions involving the immunological system. By studying nociceptive mechanisms across autoimmune illnesses, we want to identify shared pathways and activation of nociceptors specific to individual diseases. This will shed insight on potential therapies for managing pain associated with autoimmune diseases.

ATP ion channel-type P2X purinergic receptors as a key regulatory molecule in breast cancer progression

Studies have confirmed that ATP ion channel P2X purinergic receptors play a key role in tumor growth and metastasis. Similarly, P2X purinergic receptors can be used as a favorable regulatory molecule of breast cancer cells to participate in the progression of breast cancer. There are abundant ATP and its cleavage products in breast cancer microenvironment, which can be used as natural activators of P2X purinergic receptors. P2X purinergic receptors play a role in regulating the growth and metastasis of breast cancer cells by mediating signal transduction, growth regulation and immune cell activity in microenvironment. However, the application of P2X purinergic receptors antagonist has the pharmacological characteristics of inhibiting the progression of breast cancer cells. Among P2X purinergic receptors, there is a close relationship between P2X7 receptor and breast cancer patients. P2X purinergic receptors can be used as a biological marker for breast cancer patients. In this paper, we discuss the functional role and regulatory molecular mechanism of P2X purinergic receptors in the progression of breast cancer. The pharmacological effects of P2X purinergic receptors selective antagonist on the growth, metastasis and invasion of breast cancer cells were further discussed. Therefore, P2X purinergic receptors can be used as a key regulatory molecule of breast cancer and a pharmacological target for potential therapy.

Establishment and behavioural characterization of a novel constitutive P2X7 receptor knockout mouse line

The P2X7 receptor is an adenosine triphosphate (ATP)-gated ion channel expressed in different cell types of the brain. Polymorphisms in the P2RX7 gene have repeatedly been associated with psychiatric disorders including major depression. Depression is a stress-related disorder in which a dysregulation of the immune system has attracted increasing attention as a potential disease mechanism. The well-documented role of P2X7 in inflammatory conditions advocates its involvement in immune system dysregulation and depression genesis. However, understanding its exact role requires further research using appropriate animal models. Unfortunately, some of the most widely used P2X7 knockout mouse models are limited in their utility by the continuous expression of certain P2rx7 splice variants or even activation of de novo transcripts. To overcome this limitation, we generated a novel constitutive and complete P2X7 KO mouse line. These KO mice lack all known murine splice variants and protein expression resulting in a loss-of-function as confirmed by calcium imaging and by the inability of P2X7-deficient peritoneal macrophages to mount an appropriate interleukin (IL)-1β response. Comprehensive characterization using a battery of tests assessing locomotion, anxiety- and depression-related as well as social behaviour revealed differences in locomotor and exploratory behaviours. P2X7 KO mice showed slightly increased locomotor activity and reduced anxiety-related behaviour at baseline. Under conditions of chronic stress exposure, genotype-dependent differences largely dissolved while P2X7 deficiency promoted enhanced stress resilience with regard to social behaviour. Taken together, our findings add further evidence for an involvement of the P2X7 in shaping different behavioural responses and their modulation by stressful environments. This novel loss-of-function model will contribute to a better understanding of P2X7 in stress-associated behaviours in basic and translational neuropsychiatric research.

Priming and release of cytokine IL-1β in microglial cells from the retina

The P2X7 receptor (P2X7R) for extracellular ATP is implicated in several forms of retinal degeneration, including diabetic retinopathy, age-related macular degeneration, and glaucoma. P2X7R stimulation can trigger release of master cytokine IL-1β from microglia in the brain and from macrophages, but evidence of release from retinal microglia is indirect. Isolated mouse and rat retinal microglia, and wholemounts from Cx3CR1+/GFP mice, were examined to determine if ATP induced IL-1β release directly from retinal microglial cells and if it also primed expression of IL-1β on an mRNA and protein level. Isolated retinal microglia were ramified and expressed low levels of polarization markers unless provoked. Over 90% of isolated microglial cells expressed P2X7R, with cytoplasmic Ca2+ elevation following receptor stimulation. ATP induced a dose-dependent release of IL-1β from primed microglial cells that was blocked by P2X7R antagonist A839977 and emulated by agonist BzATP. P2X7R stimulation also primed Il1b mRNA in isolated microglia cells. BzATP increased IL-1β immunostaining and GFP fluorescence throughout lamina of retinal wholemounts from CX3CR1+/GFP mice. Some of the IL-1β and GFP signals colocalized, particularly in the outer retina, and in projections extending distally through photoreceptor layers. The inner retina had more microglia without IL-1β, and more IL-1β staining without microglia. Substantial IL-1β release was also detected from rat retinal microglial cells, but not optic nerve head astrocytes. In summary, this study implicates microglial cells as a key source of released IL-1β when levels of extracellular ATP are increased following retinal damage, and suggest a greater participation in the outer retina.

The vasoconstrictor adenosine 5'-tetraphosphate is a danger signal that induces IL-1β

BACKGROUND

The endogenous nucleotide adenosine 5'-tetraphosphate (Ap4) is a potent vasoconstrictor. Despite its structural similarity to the danger signal adenosine 5'-triphosphate (ATP), the immunomodulatory effects of Ap4 remain unclear.

METHODS

Modulation of interleukin (IL)-1β secretion by Ap4 was studied in both immune cells lines (THP-1, U937) and primary immune cells. Genetic and pharmacological approaches were used to characterize signaling. Cytokine production was measured using ELISA and multiplex assays, while cell viability was determined by MTT and LDH assays. Calcium influx and YO-PRO-1 uptake were assessed via microplate assays and flow cytometry, respectively. RNA sequencing and Western blotting were performed to analyze global gene expression and protein levels.

RESULTS

We demonstrate that Ap4 stimulates IL-1β release in primed immune cells without affecting the levels of other cytokines, suggesting specificity in its immunomodulatory actions. Mechanistically, Ap4-induced IL-1β release was partially modulated by the P2X7 receptor, a key mediator of inflammation. However, unlike canonical inflammasome activators, this process was independent of potassium efflux, the NLRP3 inflammasome, and caspase-1. Ap4 specifically increased LDH release in macrophages irrespective of priming. Furthermore, Ap4-mediated calcium influx, crucial for immune cell activation, predominantly occurred through P2Y receptors rather than P2X7 receptors. Transcriptomic analysis highlighted Ap4-induced upregulation of metallothioneins, implicating metal ion homeostasis in Ap4-mediated responses.

CONCLUSIONS

Collectively, our findings suggest Ap4 as a novel pro-inflammatory mediator capable of inducing IL-1β release in innate immune cells through distinct mechanisms from classical NLRP3 inflammasome activators, shedding light on its potential role in inflammatory diseases and vascular disorders.

Characterization of the Active Enantiomer and Mapping of the Stereospecific Intermolecular Pattern of a Reference P2X7 Allosteric Antagonist

The P2X purinergic receptor 7 (P2X7) has an essential role in inflammation, innate immunity, tumor progression, neurodegenerative diseases, and several other diseases, leading subsequently to the development of P2X7 modulators. AZ11645373 is a frequently studied P2X7 antagonist tool compound but always used as a racemic mixture. Racemic AZ11645373 can be separated into its respective enantiomers by chiral chromatography, albeit in small batches, and these were stereochemically intact over two years later, by chiral high-performance liquid chromatography (HPLC) analysis. On a higher scale, significant decomposition is observed during purification. One of the enantiomers was crystallized as a palladium complex, and its (R)-configuration was determined by single-crystal X-ray diffraction, further confirmed, in solution, by vibrational circular dichroism. Biological studies demonstrated that both (S)- and (R)-forms were able to fully inhibit human P2X7, but (R)-AZ11645373 was more potent, with an IC50 of 32.9 nM. Contrary to its effect on human P2X7, (S)-AZ11645373 was ineffective on mouse P2X7, while the (R)-AZ11645373 enantiomer was a full antagonist. These results demonstrated that the antagonistic effects of racemic AZ11645373 are mainly due to its (R)-enantiomer. Site-directed mutagenesis and molecular dynamics simulations indicated that the (R)-enantiomer may form specific interactions with Phe95 and the antagonists bound to other P2X7 monomers. Phe95 is situated in the allosteric binding site at the edge of the upper vestibule and appears to be the pivotal molecular gateway between AZ11645373 allosteric binding and locking of the closed state of the P2X7 channel. All together, these structure-function relationships should be helpful for drug design of P2X7 modulators.

Fluorescence detection of adenosine triphosphate based on dimeric G-quadruplex

Adenosine triphosphate (ATP) is a major chemical energy carrier in organisms and is involved in numerous biological processes. ATP levels are associated with many diseases, cell viability, and food freshness. Thus, it has become an important biomarker. Many strategies have been used to detect ATP. However, the problems of difficult-to-prepare materials, too much dependence on instruments, and complicated processes restrict the application of these methods. In this study, we proposed a novel ATP detection sensor. The method is based on the fluorescence enhancement effect of dimeric G-quadruplex (Di-G4) on thioflavin T (ThT). First, the cleavage of Di-G4 by S1 nuclease decreases system fluorescence. However, it can be recovered by increases in ATP concentrations, which act as an inhibitor of S1 nuclease. Under the optimized conditions, a good linear relationship was observed between fluorescence intensity and ATP concentrations within the range of 0.5-120 µM. The detection limit was 245 nM. The method was utilized to measure the ATP content in apples and compared with ATP assay kits, resulting in satisfactory results.

Pannexin-1 regulation of ATP release promotes the invasion of pituitary adenoma

PURPOSE

Pannexin-1 (PANX1) channel participates in the development and progression of many tumor types, however, its role of PANX1 in invasive pituitary adenoma (PA) remains unknown. The current study was designed to investigate the role of PANX1 in invasion of PA.

METHODS

We examined the expression of PANX1 in 116 surgical invasion and non-invasion PA samples (60 for bulk transcriptome and 56 for immunohistochemistry). The effects of PANX1 on PA growth were assessed in vitro and xenograft models. Meanwhile, the metabolism changes of PA cells are explored via transcriptomics and metabolomics using integration strategy.

RESULTS

PANX1 is significantly upregulated in invasive PA compared with noninvasive PA and pituitary gland, and have a potential diagnostic signature for invasive PA. Accordingly, overexpression of PANX1 could promote the proliferation and invasion of GH3 and MMQ cell lines in vitro and in vivo. Further metabolomics results confirme that overexpression of PANX1 could trigger changes in several metabolic pathways of GH3 cells. Among the dysregulated cellular metabolites, decreased intracellular ATP suggeste that PANX1 may promote the invasion of PA through impacting extracellular ATP concentration. Mechanistically, extracellular ATP might promote Ca2+ influx and upregulated the expression of MMP2/9 by activating P2X7R. Additionally, PANX1-ATP-P2 X7R signaling pathway might enhance GH3 cell invasion by remodeling the actin cytoskeleton.

CONCLUSION

Our findings point to a pivotal role of PANX1 in promoting PA invasion, which indicated a potential therapeutic target for invasive PA.

Novel Naphthyridones Targeting Pannexin 1 for Colitis Management

Pannexin 1 (PANX1) forms cell-surface channels capable of releasing signaling metabolites for diverse patho-physiological processes. While inhibiting dysregulated PANX1 has been proposed as a therapeutic strategy for many pathological conditions, including inflammatory bowel disease (IBD), low efficacy, or poor specificity of classical PANX1 inhibitors introduces uncertainty for their applications in basic and translational research. Here, hit-to-lead optimization is performed and a naphthyridone, compound 12, is identified as a new PANX1 inhibitor with an IC50 of 0.73 µm that does not affect pannexin-homologous LRRC8/SWELL1 channels. Using structure-activity relationship analysis, mutagenesis, cell thermal shift assays, and molecular docking, it is revealed that compound 12 directly engages PANX1 Trp74 residue. Using a dextran sodium sulfate mouse model of IBD, it is found that compound 12 markedly reduced colitis severity, highlighting new PANX1 inhibitors as a proof-of-concept treatment for IBD. These data describe the mechanism of action for a new PANX1 inhibitor, uncover the binding site for future drug design, and present a targeted strategy for treating IBD.

Mesenchymal stem cell-derived extracellular vesicles in periodontal bone repair

Periodontitis is a chronic inflammatory disease that destroys tooth-supporting structures and poses significant public health challenges due to its high prevalence and links to systemic health conditions. Traditional treatments are effective in reducing the inflammatory response and improving the clinical symptoms of periodontitis. However, these methods are challenging to achieve an ideal treatment effect in alveolar bone repair. Mesenchymal stem cells (MSCs) represent a potential alternative for the treatment of periodontal bone defects due to their self-renewal and differentiation capabilities. Recent research indicates that MSCs exert their effects primarily through paracrine mechanisms. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) serve as pivotal mediators in intercellular communication, transferring microRNAs (miRNAs), messenger RNAs (mRNAs), proteins, and cytokines to recipient cells, thereby emulating the therapeutic effects of MSCs. In periodontitis, MSC-EVs play a pivotal role in immunomodulation and bone remodeling, thereby facilitating periodontal bone repair. As a cell-free therapy, MSC-EVs demonstrate considerable clinical potential due to their specialized membrane structure, minimal immunogenicity, low toxicity, high biocompatibility, and nanoscale size. This review indicates that MSC-EVs represent a promising approach for periodontitis treatment, with the potential to overcome the limitations of traditional therapies and offer a more effective solution for bone repair in periodontal disease. In this review, we introduce MSC-EVs, emphasizing their mechanisms and clinical applications in periodontal bone repair. It synthesizes recent advances, existing challenges, and future prospects to present up-to-date information and novel techniques for periodontal regeneration and to guide the improvement of MSC-EV therapy in clinical practice.

Dexmedetomidine Alleviates Acute Stress-Induced Acute Kidney Injury by Attenuating Inflammation and Oxidative Stress via Inhibiting the P2X7R/NF-κB/NLRP3 Pathway in Rats

This study aimed to investigate the potential protective effects of Dexmedetomidine (DEX) against acute kidney injury (AKI) induced by acute stress (AS). Wistar rats were divided into five groups: Control, DEX, AS, AS + DEX, and AS + A438079. The results showed that AS led to AKI by increasing inflammatory biomarkers and oxidative stress-related indicators. The acute stress model in rats was successfully established. Renal function, histopathology, oxidative stress, and inflammation were assessed. Localization of P2X7 receptor (P2X7R) was determined by immunofluorescence. Additionally, the key inflammatory proteins of the P2X7R/NF-κB/NLRP3 signaling pathway were measured by Western blotting. DEX significantly improved kidney function, alleviated kidney injury, and reduced oxidative stress and inflammation. DEX inhibited the activation of the P2X7R, decreased the expression of NF-κB, NLRP3 inflammasome, and Caspase-1, and inhibited the expression of interleukin-1β (IL-1β) and tumor necrosis factor α (TNFα). Furthermore, DEX also alleviated AS-induced AKI by inhibiting the excessive production of reactive oxygen species (ROS) and reducing oxidative stress. In conclusion, DEX attenuates AS-induced AKI by mitigating inflammation and oxidative stress through the inhibition of the P2X7R/NF-κB/NLRP3 pathway in rats.

Tangzu granule alleviate neuroinflammation in diabetic peripheral neuropathy by suppressing pyroptosis through P2X7R /NLRP3 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes mellitus, mainly manifested as paresthesia. Tangzu granule (TZG) is derived from famous traditional Chinese medicine decoctions and optimized by long-term temporary practice. TZG has good efficacy in improving numbness, pain and pruritus of the lower extremities of DPN patients. However, the overall regulatory mechanisms underlying its effects on DPN remain unclear.

AIM OF THE STUDY

This study aims to explore the potential mechanism of TZG for treating DPN.

MATERIALS AND METHODS

Sprague-Dawley (SD) rats were used to establish an in vivo model of DPN with streptozotocin (STZ) injection and high-fat diet (HFD) feeding. Additionally, sciatic glial RSC96 cells were induced with high glucose in vitro. SD rats in intervention group received TZG treatment for 12 weeks. After 12 weeks of treatment, sciatic nerve function was evaluated by intelligent hot plate meter and neuro electrophysiology detector. The morphological changes of sciatic nerve cells were observed by hematoxylin-eosin staining and transmission electron microscope. IL-1β, IL-18 inflammatory cytokines, pyroptosis and P2X7R/NLRP3 signaling pathway were observed by Western blotting, immunofluorescence staining and ELISA.

RESULTS

TZG improved nerve conduction velocity and sciatic neuropathy rational structural changes in DPN rats. It also inhibited RSC96 inflammatory response and cell death that induced by high glucose. This may be related to TZG inhibiting P2X7R, decreasing the activation of NLRP3 inflammasomes, down-regulating the levels of pyroptosis proteins such as caspase-1, cleaved caspase-1, gasdermin D (GSDMD), and GSDMD-N, and inhibiting the release of interleuki (IL)-18 and IL-1β inflammatory cytokines.

CONCLUSIONS

TZG inhibited pyroptosis through P2X7R/NLRP3 signaling pathway, alleviated neuroinflammation, and showed protective effect in the treatment of DPN.

Impaired LPS Signaling in Macrophages Overexpressing the P2X7 C-Terminal Domain or Anti-P2X7 C-Terminal Domain Intrabody

The P2X7 receptor is involved in innate immune responses, with its intracellular C-terminal domain capable of interacting with signaling molecules to regulate immune cell activation; however, the mechanisms underlying the signaling complexes remain unclear. To elucidate the function of the P2X7 C-terminal domain, we established bone marrow-derived macrophage (BMDM) cell lines from transgenic (Tg) mice overexpressing the C-terminal domain of P2X7 or anti-P2X7 C-terminal domain single-chain variable fragment (scFv) intrabody. In contrast to wild-type mouse BMDMs, the Tg BMDMs showed impairment of inflammatory responses induced by lipopolysaccharide (LPS) stimulation, such as NF-κB activation and subsequent TNF-α, IL-1β, and IL-6 expression. Furthermore, P2X7 was specifically associated with myeloid differentiation primary response gene 88 (MyD88) in wild-type BMDMs; its specific interaction was strongly interfered with by overexpression of the P2X7 C-terminal domain or anti-P2X7 C-terminal domain scFv in Tg BMDMs. These observations strongly suggest that P2X7 may have pivotal roles in LPS signaling cascades and could modulate macrophage inflammatory responses through its C-terminal domain.

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.

Alzheimer's disease and infectious agents: a comprehensive review of pathogenic mechanisms and microRNA roles

Alzheimer's Disease (AD) is the most prevalent type of dementia and is characterized by the presence of senile plaques and neurofibrillary tangles. There are various theories concerning the causes of AD, but the connection between viral and bacterial infections and their potential role in the pathogenesis of AD has become a fascinating area of research for the field. Various viruses such as Herpes simplex virus 1 (HSV-1), Epstein-Barr virus (EBV), Cytomegalovirus (CMV), influenza viruses, and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), as well as bacteria such as Chlamydia pneumoniae (CP), Helicobacter pylori (HP), Porphyromonas gingivalis (P. gingivalis), Spirochetes and eukaryotic unicellular parasites (e.g., Toxoplasma gondii), have been linked to AD due to their ability to activate the immune system, induce inflammation and increase oxidative stress, thereby leading to cognitive decline and AD. In addition, microRNAs (miRNAs) might play a crucial role in the pathogenesis mechanisms of these pathogens since they are utilized to target various protein-coding genes, allowing for immune evasion, maintaining latency, and suppressing cellular signaling molecules. Also, they can regulate gene expression in human cells. This article provides an overview of the association between AD and various infectious agents, with a focus on the mechanisms by which these pathogens may be related to the pathogenesis of AD. These findings suggest important areas for further research to be explored in future studies.

Role of P2 × 7 receptor during focused ultrasound induced blood brain barrier modulation

Although low-intensity focused ultrasound (LiFUS) with microbubbles is used to temporally open the blood-brain barrier (BBB), the underlying mechanism is not fully understood. This study aimed to analyze BBB-related alterations in the brain microenvironment after LiFUS, with a focus on the involvement of the purinergic P2 × 7 receptor. Sprague-Dawley rats were sonicated with LiFUS at 0.3 MPa energy. The impact of LiFUS on the P2 × 7 receptor and inflammatory-related proteins, including NLRP3 and interleukin-1β, was analyzed through western blotting. The BBB-associated tight junction proteins, zonula occludens-1 (ZO-1) and occludin, were also analyzed. BBB permeability was assessed by quantifying the amount of Evans blue dye penetration using spectrophotometry. Furthermore, the safety of the sonication procedure was verified via terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and hematoxylin and eosin staining. Substantial increases in the P2 × 7 receptor and its downstream signaling were confirmed after sonicating the BBB with LiFUS for 1 h (p < 0.05). Conversely, for tight junction proteins, the lowest expression was observed at 1 h (p < 0.001). Both responses were normalized back to the original state over time. No evidence of brain damage was observed during the procedure. Furthermore, the P2 × 7 receptor antagonist-injected group showed reduced Evans blue dye penetration compared to that 1 h after FUS, indicating a mitigated impact of LiFUS on the BBB. Herein, we elucidate the underlying mechanism by which LiFUS affects the BBB, with a focus on the involvement of the P2 × 7 receptor. Our findings demonstrate that the extent of BBB opening varies upon the regulation of the P2 × 7 receptor. This study provides valuable insights into the mechanisms underlying BBB modulation through LiFUS, thereby laying the foundation for expanding its applications.

Exploring the association between BDNF related signaling pathways and depression: A literature review

Depression is a debilitating mental disease that inflicts significant harm upon individuals and society, yet effective treatment options remain elusive. At present, the pathogenesis of multiple depression is not fully clear, but its occurrence can be related to biological or environmental pathways, among which Brain-derived neurotrophic factor (BDNF) can unequivocally act on two downstream receptors, tyrosine kinase receptor (TrkB) and the p75 neurotrophin receptor (p75NTR), then affect the related signal pathways, affecting the occurrence and development of depression. Accumulating studies have revealed that BDNF-related pathways are critical in the pathophysiology of depression, and their interaction can further influence the efficacy of depression treatment. In this review, we mainly summarized the signaling pathways associated with BDNF and classified them according to different receptors and related molecules, providing promising insights and future directions in the treatment of depression.

Exploring β-caryophyllene: a non-psychotropic cannabinoid's potential in mitigating cognitive impairment induced by sleep deprivation

Sleep deprivation or sleep loss, a prevalent issue in modern society, is linked to cognitive impairment, leading to heightened risks of errors and accidents. Chronic sleep deprivation affects various cognitive functions, including memory, attention, and decision-making, and is associated with an increased risk of neurodegenerative diseases, cardiovascular issues, and metabolic disorders. This review examines the potential of β-caryophyllene, a dietary non-psychotropic cannabinoid, and FDA-approved flavoring agent, as a therapeutic solution for sleep loss-induced cognitive impairment. It highlights β-caryophyllene's ability to mitigate key contributors to sleep loss-induced cognitive impairment, such as inflammation, oxidative stress, neuronal death, and reduced neuroplasticity, by modulating various signaling pathways, including TLR4/NF-κB/NLRP3, MAPK, Nrf2/HO-1, PI3K/Akt, and cAMP/PKA/CREB. As a naturally occurring, non-psychotropic compound with low toxicity, β-caryophyllene emerges as a promising candidate for further investigation. The review underscores the therapeutic potential of β-caryophyllene for sleep loss-induced cognitive impairment and provides mechanistic insights into its action on crucial pathways, suggesting that β-caryophyllene could be a valuable addition to strategies aimed at combating cognitive impairment and other health issues due to sleep loss.

PET imaging of neuroinflammation: any credible alternatives to TSPO yet?

Over the last decades, the role of neuroinflammation in neuropsychiatric conditions has attracted an exponentially growing interest. A key driver for this trend was the ability to image brain inflammation in vivo using PET radioligands targeting the Translocator Protein 18 kDa (TSPO), which is known to be expressed in activated microglia and astrocytes upon inflammatory events as well as constitutively in endothelial cells. TSPO is a mitochondrial protein that is expressed mostly by microglial cells upon activation but is also expressed by astrocytes in some conditions and constitutively by endothelial cells. Therefore, our current understanding of neuroinflammation dynamics is hampered by the lack of alternative targets available for PET imaging. We performed a systematic search and review on radiotracers developed for neuroinflammation PET imaging apart from TSPO. The following targets of interest were identified through literature screening (including previous narrative reviews): P2Y12R, P2X7R, CSF1R, COX (microglial targets), MAO-B, I2BS (astrocytic targets), CB2R & S1PRs (not specific of a single cell type). We determined the level of development and provided a scoping review for each target. Strikingly, astrocytic biomarker MAO-B has progressed in clinical investigations the furthest, while few radiotracers (notably targeting S1P1Rs, CSF1R) are being implemented in clinical investigations. Other targets such as CB2R and P2X7R have proven disappointing in clinical studies (e.g. poor signal, lack of changes in disease conditions, etc.). While astrocytic targets are promising, development of new biomarkers and tracers specific for microglial activation has proven challenging.

The Anti-Human P2X7 Monoclonal Antibody (Clone L4) Can Mediate Complement-Dependent Cytotoxicity of Human Leukocytes

P2X7 is an extracellular adenosine 5'-triphosphate (ATP)-gated cation channel that plays various roles in inflammation and immunity. P2X7 is present on peripheral blood monocytes, dendritic cells (DCs), and innate and adaptive lymphocytes. The anti-human P2X7 monoclonal antibody (mAb; clone L4), used for immunolabelling P2X7 or blocking P2X7 activity, is a murine IgG2b antibody, but its ability to mediate complement-dependent cytotoxicity (CDC) is unknown. In this study the functionality of this mAb was confirmed by inhibition of ATP-induced Ca2+ responses in HEK-293 cells expressing P2X7 (HEK-P2X7). Spectrophotometric measurements of lactate dehydrogenase release demonstrated that the anti-P2X7 mAb mediated CDC in HEK-P2X7 but not HEK-293 cells. Further, flow cytometric measurements of the viability dye, 7-aminoactinomycin D, showed that this mAb mediated CDC in human RPMI 8226 but not mouse J774 cells. Immunolabelling with this mAb and flow cytometry revealed that relative amounts of cell surface P2X7 varied between human peripheral blood leukocytes. As such, the anti-P2X7 mAb preferentially mediated CDC of leukocytes that displayed relatively high cell surface P2X7, namely monocytes, DCs, natural killer T cells, myeloid-derived suppressor cells, and T helper 17 cells. Together, this data highlights a novel approach to target cellular P2X7 and to limit unwanted P2X7 functions.

Purinergic Receptor (P2X7R): A Promising Anti-Parkinson's Drug Target

Purpose

Parkinson's disease (PD) is the fourth most common neurodegenerative disorder, characterized by degeneration of basal ganglia and a decrease in dopamine levels in the brain. Purinergic 2X7 receptors (P2X7Rs) serve as inflammation gatekeepers. They are found in both central and peripheral nervous systems (CNS & PNS), and are activated in glial cells during inflammation. Purinergic 2X receptors (P2XRs) have been extensively studied in recent decades, particularly P2X7R, because of their important role in neuroinflammation caused by selective overexpression in glial cells. As P2X7R and its selective antagonists may provide neuroprotection by preventing the release of inflammatory mediators such as IL-1, they have become a research focus in PD. The review covers structure, signalling, molecular mechanisms, neuroprotective role, and current developments of P2X7R antagonists in PD.

Methods

A systematic analysis and review of the potential prospects of P2X7R antagonists in the treatment of PD were conducted by analyzing existing research data and reports published between 1996 and present.

Results

There is a substantial body of evidence linking P2X7R to pathology of PD. As a result, P2X7R antagonists may have therapeutic potential in treatment of PD.

Conclusion

P2X7R has been demonstrated as an efficacious target in PD. Recent advances in rational drug design have paved the way for development of therapeutically valuable P2X7R antagonists such as adamantyl cyanoguanides, small molecular weight compounds, and PET ligands for the treatment of PD. However, the exact molecular mechanism and therapeutic potential of P2X7R antagonists in treatment of PD are yet to be fully explored.

Selenoprotein P is a target for regulating extracellular vesicle biogenesis and secretion from activated microglia in vivo

Microglia, brain innate immune cells, participate in the spread of inflammatory signals and aggregated proteins through secretion of extracellular vesicles (EVs). Selenoprotein P (Sepp1) is a potential regulator of microglial EV secretion. Here, we investigate the effect of Sepp1 silencing on microglial transcriptomics to elucidate the Sepp1 regulatory mechanism of EV secretion and validate this effect in APPNL-G-F knockin mice. Silencing of Sepp1 significantly reduces EV secretion and CD63 loading to EVs from BV-2 microglia, as determined by single-vesicle flow cytometry and super-resolution microscopy. Sepp1 deficiency downregulates EV biogenesis machinery, accompanied by increased lysosomal activity and lipid metabolism. Silencing of Sepp1 in astrocytes but not neurons suppresses EV secretion in vitro. Finally, Sepp1 silencing reduces EV secretion from activated neurodegenerative microglia associated with amyloid plaques in APPNL-G-F mouse brains in vivo. Sepp1 is thus an emerging therapeutic target for ameliorating microglia-mediated disease spread through EV secretion in neurodegenerative disorders.

Inflammasomes in neurodegenerative diseases

Inflammasomes represent a crucial component of the innate immune system, which respond to threats by recognizing different molecules. These are known as pathogen-associated molecular patterns (PAMPs) or host-derived damage-associated molecular patterns (DAMPs). In neurodegenerative diseases and neuroinflammation, the accumulation of misfolded proteins, such as beta-amyloid and alpha-synuclein, can lead to inflammasome activation, resulting in the release of interleukin (IL)-1β and IL-18. This activation also induces pyroptosis, the release of inflammatory mediators, and exacerbates neuroinflammation. Increasing evidence suggests that inflammasomes play a pivotal role in neurodegenerative diseases. Therefore, elucidating and investigating the activation and regulation of inflammasomes in these diseases is of paramount importance. This review is primarily focused on evidence indicating that inflammasomes are activated through the canonical pathway in these diseases. Inflammasomes as potential targets for treating neurodegenerative diseases are also discussed.

Mechanism of action of the nucleotide-binding oligomerization domain-like receptor protein 3 inflammasome and its regulation in liver injury

ABSTRACT

Nucleotide-binding oligomerization domain (NOD)-like receptor protein 3 (NLRP3) is a cytosolic pattern recognition receptor that recognizes multiple pathogen-associated molecular patterns and damage-associated molecular patterns. It is a cytoplasmic immune factor that responds to cellular stress signals, and it is usually activated after infection or inflammation, forming an NLRP3 inflammasome to protect the body. Aberrant NLRP3 inflammasome activation is reportedly associated with some inflammatory diseases and metabolic diseases. Recently, there have been mounting indications that NLRP3 inflammasomes play an important role in liver injuries caused by a variety of diseases, specifically hepatic ischemia/reperfusion injury, hepatitis, and liver failure. Herein, we summarize new research pertaining to NLRP3 inflammasomes in hepatic injury, hepatitis, and liver failure. The review addresses the potential mechanisms of action of the NLRP3 inflammasome, and its regulation in these liver diseases.

The Neuroprotective Role of A2A Adenosine Purinoceptor Modulation as a Strategy Against Glioblastoma

Glioblastoma (GBM) is a highly lethal type of cancer, frequently presenting an unfavorable prognosis. The current treatment options for this neoplasia are still limited, highlighting the need for further research evaluating new drugs to treat GBM or to serve as an adjuvant to improve the efficiency of currently used therapies. In this sense, the inhibition of A2A receptors in the brain has presented a neuroprotective role for several diseases, such as neurodegenerative conditions, and it has been suggested as a possible pharmacological target in some types of cancer; thus, it also can be underscored as a potential target in GBM. Recently, Istradefylline (IST) was approved by the FDA for treating Parkinson's disease, representing a safe drug that acts through the inhibition of the A2A receptor, and it has also been suggested as an antineoplastic drug. Therefore, this work aims to explore the effects of A2A receptor inhibition as a therapy for GBM and assess the feasibility of this blockage occurring through the effects of IST.

Molecular Mechanisms of Rett Syndrome: Emphasizing the Roles of Monoamine, Immunity, and Mitochondrial Dysfunction

Rett syndrome (RTT), which predominantly affects females, arises in most cases from mutations in the Methyl-CpG-binding Protein-2 (MECP2) gene. When MeCP2 is impaired, it disrupts the regulation of numerous genes, causing the production of dysfunctional proteins associated with various multi-systemic issues in RTT. In this review, we explore the current insights into molecular signaling related to monoamines, immune response, and mitochondrial function, and their implications for the pathophysiology of RTT. Research has shown that monoamines-such as dopamine, norepinephrine, epinephrine, serotonin, and histamine-exhibit alterations in RTT, contributing to a range of neurological symptoms. Furthermore, the immune system in RTT individuals demonstrates dysfunction through the abnormal activity of microglia, macrophages, lymphocytes, and non-immune cells, leading to the atypical release of inflammatory mediators and disruptions in the NF-κB signaling pathway. Moreover, mitochondria, essential for energy production and calcium storage, also show dysfunction in this condition. The delicate balance of producing and scavenging reactive oxygen species-termed redox balance-is disrupted in RTT. Targeting these molecular pathways presents a promising avenue for developing effective therapies.

Biological and pharmacological roles of pyroptosis in pulmonary inflammation and fibrosis: recent advances and future directions

Pyroptosis, an inflammatory regulated cell death (RCD) mechanism, is characterized by cellular swelling, membrane rupture, and subsequent discharge of cellular contents, exerting robust proinflammatory effects. Recent studies have significantly advanced our understanding of pyroptosis, revealing that it can be triggered through inflammasome- and caspase-independent pathways, and interacts intricately with other RCD pathways (e.g., pyroptosis, necroptosis, ferroptosis, and cuproptosis). The pathogenesis of pulmonary fibrosis (PF), including idiopathic pulmonary fibrosis (IPF) and other interstitial lung diseases, involves a multifaceted interplay of factors such as pathogen infections, environmental pollutants, genetic variations, and immune dysfunction. This chronic and progressive interstitial lung disease is characterized by persistent inflammation, extracellular matrix (ECM) accumulation, and fibrotic alveolar wall thickening, which potentially contribute to deteriorated lung function. Despite recent advances in understanding pyroptosis, the mechanisms by which it regulates PF are not entirely elucidated, and effective strategies to improve clinical outcomes remain unclear. This review strives to deliver a comprehensive overview of the biological functions and molecular mechanisms of pyroptosis, exploring its roles in the pathogenesis of PF. Furthermore, it examines potential biomarkers and therapeutic agents for anti-fibrotic treatments.

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.

Selective regulation of IFN-γ and IL-4 co-producing unconventional T cells by purinergic signaling

Unconventional T cells, including mucosal-associated invariant T (MAIT), natural killer T (NKT), and gamma-delta T (γδT) cells, comprise distinct T-bet+, IFN-γ+ and RORγt+, IL-17+ subsets which play differential roles in health and disease. NKT1 cells are susceptible to ARTC2-mediated P2X7 receptor (P2RX7) activation, but the effects on other unconventional T-cell types are unknown. Here, we show that MAIT, γδT, and NKT cells express P2RX7 and are sensitive to P2RX7-mediated cell death. Mouse peripheral T-bet+ MAIT1, γδT1, and NKT1 cells, especially in liver, co-express ARTC2 and P2RX7. These markers could be further upregulated upon exposure to retinoic acid. Blocking ARTC2 or inhibiting P2RX7 protected MAIT1, γδT1, and NKT1 cells from cell death, enhanced their survival in vivo, and increased the number of IFN-γ-secreting cells without affecting IL-17 production. Importantly, this revealed the existence of IFN-γ and IL-4 co-producing unconventional T-cell populations normally lost upon isolation due to ARTC2/P2RX7-induced death. Administering extracellular NAD in vivo activated this pathway, depleting P2RX7-sensitive unconventional T cells. Our study reveals ARTC2/P2RX7 as a common regulatory axis modulating the unconventional T-cell compartment, affecting the viability of IFN-γ- and IL-4-producing T cells, offering important insights to facilitate future studies into how these cells can be regulated in health and disease.

Immunogenic cell death-related cancer-associated fibroblast clusters and prognostic risk model in cervical cancer

Cervical cancer (CC) remains a leading cause of female cancer mortality globally. Immunogenic cell death (ICD) influences the tumor microenvironment (TME) and adaptive immune responses. Cancer-associated fibroblasts (CAFs) within the TME suppress anti-tumor immunity and contribute to CC progression. This study identified three ICD-related CAF clusters linked to patient survival, including IL6+CAF and ILR1+CAF, which were associated with clinical outcomes. Using a nine-gene risk model, patients were stratified into risk groups, with high-risk individuals showing worse survival and correlations with pathways such as hypoxia and TGFβ. The model also predicted immunotherapy responses, highlighting immune infiltration differences across risk groups. These findings provide insights into the role of CAF clusters in CC and present a risk model that supports prognosis prediction and personalized therapy.

The role and mechanism of P2X7R in cirrhotic cardiomyopathy

In the context of liver cirrhosis, the incidence of myocardial inflammation and apoptosis escalates, contributing to the development and progression of cirrhotic cardiomyopathy. The P2X7 receptor, a purinergic receptor linked to inflammatory processes, has been identified in the etiology of a range of autoinflammatory, autoimmune, chronic inflammatory, and metabolic disorders. Despite this, the specific role of the P2X7 receptor in the etiology of cirrhotic cardiomyopathy remains to be elucidated. In our research, a cirrhotic cardiomyopathy animal model was established using mice subjected to bile duct ligation. The expression of the P2X7 receptor was suppressed via intraperitoneal administration of Brilliant Blue G. Cardiac function was evaluated using echocardiographic techniques, while histopathological examination and enzyme-linked immunosorbent assays were employed to assess the presence of inflammation and apoptosis in liver and cardiac tissues. The expression of key proteins, including P2X7, NLRP3, and IL-1β, in the myocardial tissue was quantified by Western blot analysis. Our research has unveiled significant findings in a murine model of liver fibrosis induced by two weeks of bile duct ligation. Notably, we detected escalated levels of liver fibrosis coupled with disruptions in liver blood flow dynamics. Concurrently, there was a marked increase in myocardial inflammation and apoptosis, which adversely affected heart function. Intriguingly, the expression of P2X7 receptors (P2X7R) in cardiac and hepatic tissues was found to be significantly elevated. Targeting and inhibiting the expression of P2X7R not only alleviated myocardial inflammation and apoptosis but also enhanced cardiac performance. Furthermore, this intervention resulted in a noticeable reduction in liver fibrosis. The interplay between the P2X7 and NLRP3 pathways emerges as a pivotal mechanism in the etiology and progression of cirrhotic cardiomyopathy. Our findings suggest that modulating the P2X7-NLRP3 axis could offer promising therapeutic avenues for managing cirrhotic cardiomyopathy.

Development progress of drugs for bipolar disorder: 75 Years after lithium proved effective

Bipolar disorder, a psychiatric condition identified by significant mood changes and a considerable genetic connection with schizophrenia, needs continuous and extensive management due to its common onset in adolescence and significant impact on psychosocial activities. While traditional mood stabilizers continue to be widely used, the pursuit of more effective treatments remains ongoing, with the current research targeting various stages of the disorder. This study provides a thorough examination of new pharmacological treatments for bipolar disorder, which are currently in Phase II and Phase III clinical trials up to 22 April 2024. A systematic search was conducted using the NIH National Library of Medicine, focusing on both repurposed and innovative drugs now in advanced stages of testing. The study identifies several promising therapeutic agents, including those intended for severe mood disorders with suicidal tendencies, and others aimed at treating mood-related neuroinflammation. Drugs that enhance dopamine stabilization and those that act on serotonin receptor activities were found notable. We also explored the strategic repurposing of already existing medications for broader therapeutic uses and looked into the potential of new formulations designed for the immediate management of symptoms. Our analysis highlights two main strategies for tackling bipolar disorder: finding new uses for existing drugs and developing new medications with unique actions. This approach shows continuous improvement in drug treatments, helping patients manage their condition better and addressing the complicated nature of bipolar disorder.

Ionotropic purinergic receptor 7 (P2X7) channel structure and pharmacology provides insight regarding non-nucleotide agonism

P2X7 is a member of the Ionotropic Purinergic Receptor (P2X) family. The P2X family of receptors is composed of seven (P2X1-7), ligand-gated, nonselective cation channels. Changes in P2X expression have been reported in multiple disease models. P2Xs have large complex extracellular domains that function as receptors for a variety of ligands, including endogenous and synthetic agonists and antagonists. ATP is the canonical agonist. ATP affinity ranges from nanomolar to micromolar for most P2XRs, but P2X7 has uniquely poor ATP affinity. In many physiological settings, it may be difficult to achieve the millimolar extracellular ATP concentrations needed for P2X7 channel activation; however, channel function is implicated in pain sensation, immune cell function, cardiovascular disease, cancer, and osteoporosis. Multiple high-resolution P2X7 structures have been solved in apo-, ATP-, and antagonist-bound states. P2X7 structural data reveal distinct allosteric and orthosteric antagonist-binding sites. Both allosteric and orthosteric P2X7 antagonists are well documented to inhibit ATP-evoked channel current. However, a growing body of evidence supports P2X7 activation by non-nucleotide agonists, including extracellular histone proteins and human cathelicidin-derived peptides (LL-37). Interestingly, P2X7 non-nucleotide agonism is not inhibited by allosteric antagonists, but is inhibited by orthosteric antagonists. Herein, we review P2X7 function with a focus on the efficacy of available pharmacology on P2X7 channel current activation by non-nucleotide agonists in effort to understand agonist/antagonist efficacy, and consider the impact of these data on the current understanding of P2X7 in physiology and disease given these limitations of P2X7-selective antagonists and incomplete knockout mouse models.