ATP-P2X4 signaling mediates NLRP3 inflammasome activation: a novel pathway of diabetic nephropathy

Possible Interaction of Suramin with Thalamic P2X Receptors and NLRP3 Inflammasome Activation Alleviates Reserpine-Induced Fibromyalgia-Like Symptoms

The high pain sensitivity in fibromyalgia (FM) is processed by the thalamus that presents as a key component in the pain pathway in FM patients. Noteworthy, Purinergic receptors, specifically P2X, are implicated in pain signaling and neuroinflammation via inflammasome signaling. However, there is no available data on the impact of pharmacological intervention on the P2X receptor in thalamic pain transmission in FM. To investigate this aspect, the clinically tested P2X inhibitor, Suramin (SURM), was utilized. FM was induced over three days using Reserpine (1 mg/kg/day, s.c.), followed by a single dose of SURM (100 mg/kg, i.p.). At the molecular level, SURM countered the overexpression of P2X7 and P2X4 receptors accompanied by reduced NLRP3 inflammasome complex and pyroptotic markers like gasdermin-D. This was associated with the suppression of the p38-MAPK and NF-κB pathways, along with a decrease in pro-inflammatory cytokines and tumor necrosis factor-α as observed by increased CD86 expression on M1 microglia phenotype, a neuroinflammatory marker. Concurrently, blocking the P2X receptor shifted microglia polarization towards the M2 phenotype, marked by elevated CD163 expression, as a neuroprotective mechanism. This was outlined by increased neurotrophic and anti-inflammatory IL-10 with normalization of disturbed neurotransmitters. Behaviorally, SURM ameliorated the heightened pain processing, as observed in mechanical and thermal pain tests. Furthermore, it lowered Reserpine-induced motor impairment in the rotarod and open-field tests. This improvement in the somatosensory experience was reflected in alleviating depressive-like behavior in the forced swimming test. These findings highlight the therapeutic potential of blocking thalamic P2X receptors in alleviating fibromyalgia symptoms.

The Role of Mitochondria in Diabetic Kidney Disease and Potential Therapeutic Targets

Diabetic kidney disease (DKD) is recognized worldwide as a leading cause of end-stage renal failure. Although therapies that target glomerular hemodynamics and can inhibit disease progression have been developed, there is currently no fundamental cure for the disease. Mitochondria play an important role in cellular respiration, producing adenosine triphosphate (ATP) by oxidative phosphorylation, and are essential for renal function, especially in proximal tubular cells (PTCs). In diabetic conditions, maintaining mitochondrial health is vital for preserving renal function. Under diabetic conditions, excessive reactive oxygen species (ROS) can damage mitochondrial DNA (mtDNA), leading to renal dysfunction. Strategies targeting mitochondrial function, such as AMP-activated protein kinase (AMPK) activation and modulation of nitric oxide (NO) availability, are promising for suppressing diabetic nephropathy. The immune response to DKD, initiated by detecting damage- and pathogen-associated molecular patterns, has a significant impact on the progression of DKD, including leakage of mtDNA and RNA, leading to inflammation through various pathways. This contributes to renal impairment characterized by hyperfiltration, endothelial dysfunction, and albuminuria. Mitochondrial energy metabolism and dynamics induced by hyperglycemia precede the onset of albuminuria and histological changes in the kidneys. The increased mitochondrial fission and decreased fusion that occur under diabetic conditions result in ATP depletion and exacerbate cellular dysfunction. Therapeutic strategies focused on restoring mitochondrial function are promising for slowing the progression of DKD and reduce the adverse effects on renal function. Sodium-glucose cotransporter-2 inhibitors (SGLT2is) and glucagon-like peptide-1 (GLP-1) receptor agonists, already in clinical use, have been shown to be protective for mitochondria, and nuclear factor erythroid 2-related factor 2 (Nrf2) activation and mitochondrial dynamics are promising drug discovery targets for further research.

A Narrative Review of Signaling Pathway and Treatment Options for Diabetic Nephropathy

BACKGROUND

Diabetic nephropathy is a progressive kidney disease that frequently results in end-stage renal disorders and is characterized by proteinuria, albuminuria, decreased filtration, and renal fibrosis. Despite the fact that there are a number of therapeutic alternatives available, DN continues to be the main contributor to end-stage renal disease. Therefore, significant innovation is required to enhance outcomes in DN patients.

METHODS

Information was collected from online search engines like, Google Scholar, Web of Science, PubMed, Scopus, and Sci-Hub databases using keywords like diabetes, nephropathy, kidney disease, autophagy, etc. Results: Natural compounds have anti-inflammatory and antioxidant properties and impact various signaling pathways. They ameliorate kidney damage by decreasing oxidative stress, inflammatory process, and fibrosis and enhance the antioxidant system, most likely by activating and deactivating several signaling pathways. This review focuses on the role of metabolic memory and various signaling pathways involved in the pathogenesis of DN and therapeutic approaches available for the management of DN. Special attention is given to the various pathways modulated by the phytoconstituents.

Clinical significance of NLRP3 inflammasome and related cell molecules in early diabetic kidney disease in elderly population

Background

The paper aims to investigate the expression level of NLRP3 inflammasome and its related cell molecules in early diabetes kidney disease (EDKD) in the elderly and its clinical application value.

Methods

From October 2021 to April 2023, 50 elderly patients with T2DM (T2DM group), 50 elderly patients with EDKD (EDKD group) and 50 elderly people who passed the health check-up (healthy group) were chosen as the study subjects. Plasma NLRP3 inflammasome and related cells (blood leukocyte count, monocyte count, lymphocyte count) molecular (NT-proBNP and others) levels are tested, and Pearson correlation analysis is utilized to explore the correlation among plasma NLRP3 inflammasome and related cells, molecules, and renal function indicators (UACR, BUN, Ucr) in elderly patients with EDKD.

Results

(1) The three groups' comparison in HbA1c, FIns, HOMA-IR, UACR, BUN, Ucr, SOD, MCP-1, and TNF-a levels were with P<0.05. The levels of TG and LDL-C in the EDKD group were higher than those in the T2DM and the healthy groups; the levels of FPG, HbA1c, FINs, HOMA-IR, UACR, SOD, MCP-1, TNF-a in the EDKD and T2DM groups were higher than those in the healthy group, while SOD was smaller than that in the healthy group; the levels of BUN, Ucr, hs-CRP, FPG, HbA1c, FINs, HOMA-IR, UACR, SOD, MCP-1, TNF-a in the EDKD group were higher than those in the T2DM group, while SOD was smaller than that in the T2DM group. The above results were with P<0.05. (2) It has P<0.05 in Monocyte count, NLRP3, NT-proBNP, caspase-1, ASC and others in the three groups. Those in the EDKD and T2DM groups were higher than those in the healthy group. The levels of these indicators in the EDKD group were higher than those in the T2DM group, with P<0.05. NLRP3, Caspase-1, ASC, IL1b, and IL-18 were positively correlated with UACR, BUN, and Ucr in the EDKD group. All the above differences were P<0.05.

Conclusions

NLRP3 inflammasome and its related molecules caspase-1, ASC, IL-1b, IL-18 and other levels increase in early elderly EDKD and are closely related to the severity of EDKD.

Role of purinoreceptors in the release of extracellular vesicles and consequences on immune response and cancer progression

Cell-to-cell communication is a major process for accommodating cell functioning to changes in the environments and to preserve tissue and organism homeostasis. It is achieved by different mechanisms characterized by the origin of the message, the molecular nature of the messenger, its speed of action and its reach. Purinergic signalling is a powerful mechanism initiated by extracellular nucleotides, such as ATP, acting on plasma membrane purinoreceptors. Purinergic signalling is tightly controlled in time and space by the action of ectonucleotidases. Recent studies have highlighted the critical role of purinergic signalling in controlling the generation, release and fate of extracellular vesicles and, in this way, mediating long-distance responses. Most of these discoveries have been made in immune and cancer cells. This review is aimed at establishing the current knowledge on the way which purinoreceptors control extracellular vesicle-mediated communications and consequences for recipient cells.

Hesperetin protects against rotenone-induced motor disability and neurotoxicity via the regulation of SIRT1/NLRP3 signaling

Rotenone is a pesticide that causes complex I inhibition and is widely known to induce motor disability and experimental Parkinson's disease (PD) in rodents. Evidence suggests a crucial role for sirtuin/nuclear factor-kappaB/nod-like receptor family, pyrin domain-containing 3 (SIRT1/NFκB/NLRP3) signaling and inflammation in PD and rotenone neurotoxicity. Hesperetin (C16H14O6) is a citrus flavonoid with documented anti-inflammatory activity. We investigated the value of hesperetin in delaying rotenone-induced PD in mice and the possible modulation of inflammatory burden. PD was induced in mice via rotenone injections. Groups were assigned as a vehicle, PD, or PD + hesperetin (50 or 100 mg/kg) and compared for the motor function, protein level (by ELISA), and gene expression (by real-time PCR) of the target proteins, histopathology, and immunohistochemistry for tyrosine hydroxylase enzyme. Hesperetin (50 or 100 mg/kg) alleviated the motor disability and the striatal dopamine level and decreased the expression of NLRP3 and NF-κB but increased SIRT1 expression (p < 0.05). Further, it enhanced the neural viability and significantly decreased neural degeneration in the substantia nigra, hippocampus, and cerebral cortex (p < 0.05). Taken together, we propose that hesperetin mediates its neuroprotective function via alleviating modulation of the SIRT1/NFκB/NLRP3 pathway. Therefore, hesperetin might delay the PD progression.

Molecular insights into P2X signalling cascades in acute kidney injury

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

Inhibitors of NLRP3 Inflammasome Formation: A Cardioprotective Role for the Gasotransmitters Carbon Monoxide, Nitric Oxide, and Hydrogen Sulphide in Acute Myocardial Infarction

Myocardial ischaemia reperfusion injury (IRI) occurring from acute coronary artery disease or cardiac surgical interventions such as bypass surgery can result in myocardial dysfunction, presenting as, myocardial "stunning", arrhythmias, infarction, and adverse cardiac remodelling, and may lead to both a systemic and a localised inflammatory response. This localised cardiac inflammatory response is regulated through the nucleotide-binding oligomerisation domain (NACHT), leucine-rich repeat (LRR)-containing protein family pyrin domain (PYD)-3 (NLRP3) inflammasome, a multimeric structure whose components are present within both cardiomyocytes and in cardiac fibroblasts. The NLRP3 inflammasome is activated via numerous danger signals produced by IRI and is central to the resultant innate immune response. Inhibition of this inherent inflammatory response has been shown to protect the myocardium and stop the occurrence of the systemic inflammatory response syndrome following the re-establishment of cardiac circulation. Therapies to prevent NLRP3 inflammasome formation in the clinic are currently lacking, and therefore, new pharmacotherapies are required. This review will highlight the role of the NLRP3 inflammasome within the myocardium during IRI and will examine the therapeutic value of inflammasome inhibition with particular attention to carbon monoxide, nitric oxide, and hydrogen sulphide as potential pharmacological inhibitors of NLRP3 inflammasome activation.

Luteolin Alleviates Diabetic Nephropathy Fibrosis Involving AMPK/NLRP3/TGF-β Pathway

Purpose

Luteolin is a promising candidate for diabetic nephropathy due to its potential anti-inflammatory and anti-fibrotic properties. This study explored the molecular mechanisms through which luteolin combats fibrosis in DN.

Methods

Potential targets affected by luteolin and genes associated with DN were collected from databases. Overlapping targets between luteolin and diabetic nephropathy were identified through Venn analysis. A protein-protein interaction network was constructed using these common targets, and critical pathways and targets were elucidated through GO and KEGG analysis. These pathways and targets were confirmed using a streptozotocin-induced mouse model. Luteolin was administered at 45 mg/kg and 90 mg/kg. Various parameters were evaluated, including body weight, blood glucose levels, and histopathological examinations. Protein levels related to energy metabolism, inflammation, and fibrosis were quantified.

Results

Fifty-three targets associated with luteolin and 36 genes related to diabetic nephropathy were extracted. The AGE-RAGE signaling pathway was the key pathway impacted by luteolin in diabetic nephropathy. Key molecular targets include TGF-β, IL-1β, and PPARG. Luteolin reduced body weight and blood glucose levels, lowered the left kidney index, and improved insulin and glucose tolerance. Furthermore, luteolin mitigated inflammatory cell infiltration, basement membrane thickening, and collagen deposition in the kidney. Luteolin up-regulated the protein expression of p-AMPKα (Th172) while simultaneously down-regulated the protein expression of p-NF-ĸB (p65), NLRP3, TGF-β1, α-SMA, and Collagen I.

Conclusion

Luteolin mitigated renal fibrosis by alleviating energy metabolism disruptions and inflammation by modulating the AMPK/NLRP3/TGF-β signaling pathway.

Research Progress of Pyroptosis in Diabetic Kidney Disease

Pyroptosis, known as one typical mode of programmed cell death, is generally characterized by the cleaved gasdermin family (GSDMs) forming pores in the cell membrane and inducing cell rupture, and the activation of aspartate-specific proteases (caspases) has also been found during this process. Diabetic Kidney Disease (DKD) is caused by the complication of diabetes in the kidney, and the most important kidney's function, Glomerular Filtration Rate (GFR), happens to drop to less than 90% of its usual and even lead to kidney failure in severe cases. The persistent inflammatory state induced by high blood glucose implies the key pathology of DKD, and growing evidence shows that pyroptosis serves as a significant contributor to this chronic immune-mediated inflammatory disorder. Currently, the expanded discovery of GSDMs, pyroptosis, and its association with innate immunity has been more attractive, and overwhelming research is needed to sort out the implication of pyroptosis in DKD pathology. In this review, we comb both classical studies and newly founds on pyroptosis, prick off the novel awakening of pyroptosis in DKD, and center on the significance of pyroptosis in DKD treatment, aiming to provide new research targets and treatment strategies on DKD.

Functional role of P2X7 purinergic receptor in cancer and cancer-related pain

Numerous studies have revealed that the ATP-gated ion channel purinergic 2X7 receptor (P2X7R) plays an important role in tumor progression and the pathogenesis of cancer pain. P2X7R requires activation by extracellular ATP to perform its regulatory role functions. During tumor development or cancer-induced pain, ATP is released from tumor cells or other cells in the tumor microenvironment (such as tumor-associated immune cells), which activates P2X7R, opens ion channels on the cell membrane, affects intracellular molecular metabolism, and regulates the activity of tumor cells. Furthermore, peripheral organs and receptors can be damaged during tumor progression, and P2X7R expression in nerve cells (such as microglia) is significantly upregulated, enhancing sensory afferent information, sensitizing the central nervous system, and inducing or exacerbating pain. These findings reveal that the ATP-P2X7R signaling axis plays a key regulatory role in the pathogenesis of tumors and cancer pain and also has a therapeutic role. Accordingly, in this study, we explored the role of P2X7R in tumors and cancer pain, discussed the pharmacological properties of inhibiting P2X7R activity (such as the use of antagonists) or blocking its expression in the treatment of tumor and cancer pain, and provided an important evidence for the treatment of both in the future.

Dexmedetomidine alleviates sevoflurane-induced neuroinflammation and neurocognitive disorders by suppressing the P2X4R/NLRP3 pathway in aged mice

PURPOSE

Microglia-mediated inflammation is associated with perioperative neurocognitive disorders (PNDs) caused by sevoflurane. Dexmedetomidine has been reported to protect against sevoflurane-induced cognitive impairment. In this study, we investigated the effects and underlying mechanisms of dexmedetomidine on sevoflurane-induced microglial neuroinflammation and PNDs.

METHODS

Wild-type and purinergic ionotropic 4 receptor (P2X4R) overexpressing C57/BL6 mice were intraperitoneally injected with 20 μg/kg dexmedetomidine or an equal volume of normal saline 2 h prior to sevoflurane exposure. The Morris water maze (MWM) test was performed to assess cognitive function. Immunofluorescence staining was employed to detect microglial activation. The expression levels of proinflammatory cytokines were measured by real-time quantitative PCR (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA). The protein levels of P2X4R and NOD-like receptor protein 3 (NLRP3) were detected by Western Blotting.

RESULTS

Sevoflurane increased the number of microglia, upregulated the levels of proinflammatory cytokines, elevated the protein levels of P2X4R and NLRP3 in the hippocampus and induced cognitive decline, while pretreatment with dexmedetomidine downregulated the protein levels of P2X4R and NLRP3, alleviated sevoflurane-induced microglial neuroinflammation and improved cognitive dysfunction. Moreover, overexpression of P2X4R weakened the neuroprotective effect of dexmedetomidine.

CONCLUSIONS

Dexmedetomidine protected against sevoflurane-induced neuroinflammation and neurocognitive disorders by suppressing the P2X4R/NLRP3 pathway.

The role of innate immunity in diabetic nephropathy and their therapeutic consequences

Diabetic nephropathy (DN) is an enduring condition that leads to inflammation and affects a substantial number of individuals with diabetes worldwide. A gradual reduction in glomerular filtration and emergence of proteins in the urine are typical aspects of DN, ultimately resulting in renal failure. Mounting evidence suggests that immunological and inflammatory factors are crucial for the development of DN. Therefore, the activation of innate immunity by resident renal and immune cells is critical for initiating and perpetuating inflammation. Toll-like receptors (TLRs) are an important group of receptors that identify patterns and activate immune responses and inflammation. Meanwhile, inflammatory responses in the liver, pancreatic islets, and kidneys involve inflammasomes and chemokines that generate pro-inflammatory cytokines. Moreover, the activation of the complement cascade can be triggered by glycated proteins. This review highlights recent findings elucidating how the innate immune system contributes to tissue fibrosis and organ dysfunction, ultimately leading to renal failure. This review also discusses innovative approaches that can be utilized to modulate the innate immune responses in DN for therapeutic purposes.

Tubular injury in diabetic kidney disease: molecular mechanisms and potential therapeutic perspectives

Diabetic kidney disease (DKD) is a chronic complication of diabetes and the leading cause of end-stage renal disease (ESRD) worldwide. Currently, there are limited therapeutic drugs available for DKD. While previous research has primarily focused on glomerular injury, recent studies have increasingly emphasized the role of renal tubular injury in the pathogenesis of DKD. Various factors, including hyperglycemia, lipid accumulation, oxidative stress, hypoxia, RAAS, ER stress, inflammation, EMT and programmed cell death, have been shown to induce renal tubular injury and contribute to the progression of DKD. Additionally, traditional hypoglycemic drugs, anti-inflammation therapies, anti-senescence therapies, mineralocorticoid receptor antagonists, and stem cell therapies have demonstrated their potential to alleviate renal tubular injury in DKD. This review will provide insights into the latest research on the mechanisms and treatments of renal tubular injury in DKD.

Inflammasomes in breast cancer: the ignition spark of progression and resistance?

Inflammation and immune evasion are major key players in breast cancer (BC) progression. Recently, the FDA approved the use of anti-programmed death-ligand 1 antibody (anti-PD-L1) and phosphoinositide 3-kinase (PI3K) inhibitors against aggressive BC. Despite the paradigm shift in BC treatments, patients still suffer from resistance, recurrence and serious immune-related adverse events. These obstacles require unravelling of the hidden molecular contributors for such therapy failure hence yielding therapeutics that are at least as efficient yet safer. Inflammasome pathway is activated when the pattern recognition receptor senses danger signals (danger-associated molecular patterns) from damagedRdying cells or pathogen-associated molecular patterns found in microbes, leading to secretion of the active pro-inflammatory cytokines interleukin-1β (IL-1β) and interleukin-18 (IL-18). It has been shown throughout numerous studies that inflammasome pathway enhanced invasion, metastasis, provoked BC progression and therapy resistance. Additionally, inflammasomes upregulated the proliferative index ki67 and enhanced PD-L1 expression leading to immunotherapy resistance. IL-1β contributed to significant decrease in oestrogen receptor levels and promoted BC chemo-resistance. High levels of IL-18 in sera of BC patients were associated with worst prognosis. Stimulation of purinergic receptors and modulation of adipokines in obese subjects activated inflammasomes that evoked radiotherapy resistance and BC progression. The micro RNA miR-223-3p attenuated the inflammasome over-expression leading to lowered tumour volume and lessened angiogenesis in BC. This review sheds the light on the molecular pathways of inflammasomes and their impacts in distinct BC subtypes. In addition, it highlights novel strategies in treatment and prevention of BC.

Long non-coding RNA MSTRG.81401 short hairpin RNA relieves diabetic neuropathic pain and behaviors of depression by inhibiting P2X4 receptor expression in type 2 diabetic rats

Patients with diabetic neuropathic pain (DNP) experience immense physical and mental suffering, which is comorbid with other mental disorders, including major depressive disorder (MDD). P2X4 receptor, one of the purinergic receptors, is a significant mediator of DNP and MDD. The present study aimed to identify the roles and mechanisms of MSTRG.81401, a long non-coding RNA (lncRNA), in alleviating DNP and MDD-like behaviors in type 2 diabetic rats. After administration with MSTRG.81401 short hairpin RNA (shRNA), the model + MSTRG.81401 shRNA group demonstrated increased mechanical withdrawal threshold, thermal withdrawal latency, open-field test, and sucrose preference test; however, immobility time on the forced swimming test decreased. MSTRG.81401 shRNA administration significantly decreased the expression of the P2X4 receptor, tumor necrosis factor-α, and interleukin-1β in the hippocampus and spinal cord in the model + MSTRG.81401 shRNA group. Simultaneously, MSTRG.81401 shRNA administration downregulated phosphorylation of ERK1/2 in the hippocampus and spinal cord. Thus, lncRNA MSTRG.81401 shRNA can alleviate DNP and MDD-like behaviors in type 2 diabetic rats and may downregulate the expression of P2X4 receptors in the hippocampus and spinal cord of rats.

ATP ion channel P2X purinergic receptors in inflammation response

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

Nanocurcumin combined with insulin alleviates diabetic kidney disease through P38/P53 signaling axis

Treatments for diabetic kidney disease (DKD) mainly focus on managing hyperglycemia and hypertension, but emerging evidence suggests that inflammation also plays a role in the pathogenesis of DKD. This 10-week study evaluated the efficacy of daily oral nanoparticulate-curcumin (nCUR) together with long-acting insulin (INS) to treat DKD in a rodent model. Diabetic rats were dosed with unformulated CUR alone, nCUR alone or together with INS, or INS alone. The progression of diabetes was reflected by increases in plasma fructosamine, blood urea nitrogen, creatinine, bilirubin, ALP, and decrease in albumin and globulins. These aberrancies were remedied by nCUR+INS or INS but not by CUR or nCUR. Kidney histopathological results revealed additional abnormalities characteristic of DKD, such as basement membrane thickening, tubular atrophy, and podocyte cytoskeletal impairment. nCUR and nCUR+INS mitigated these lesions, while CUR and INS alone were far less effective, if not ineffective. To elucidate how our treatments modulated inflammatory signaling in the liver and kidney, we identified hyperactivation of P38 (MAPK) and P53 with INS and CUR, whereas nCUR and nCUR+INS deactivated both targets. Similarly, the latter interventions led to significant downregulation of renal NLRP3, IL-1β, NF-ĸB, Casp3, and MAPK8 mRNA, indicating a normalization of inflammasome and apoptotic pathways. Thus, we show therapies that reduce both hyperglycemia and inflammation may offer better management of diabetes and its complications.

Deciphering the Role of Pyroptosis Impact on Cardiovascular Diseases

Pyroptosis has become a noteworthy area of focus in recent years due to its association with inflammatory diseases. Pyroptosis is a type of programmed cell death accompanied by an inflammatory response, and the discovery of the gasdermin family has expanded the study of pyroptosis. The primary characteristics of pyroptosis include cell expansion, membrane penetration, and the ejection of cell contents. In healthy physiology, pyroptosis is an essential part of the host's defence against pathogen infection. Excessive Pyroptosis, however, can lead to unchecked and persistent inflammatory responses, including the emergence of inflammatory diseases. More precisely, gasdermin family members have a role in the creation of membrane holes during pyroptosis, which leads to cell lysis. It is also related to how pro-inflammatory intracellular substances, including IL-1, IL-18, and High mobility group box 1 (HMGB1), are used. Two different signalling pathways, one of which is regulated by caspase-1 and the other by caspase-4/5/11, are the primary causes of pyroptosis. Cardiovascular diseases are often associated with cell death and acute or chronic inflammation, making this area of research particularly relevant. In this review, we first systematically summarize recent findings related to Pyroptosis, exploring its characteristics and the signalling pathway mechanisms, as well as various treatment strategies based on its modulation that has emerged from the studies. Some of these strategies are currently undergoing clinical trials. Additionally, the article elaborates on the scientific evidence indicating the role of Pyroptosis in various cardiovascular diseases. As a whole, this should shed insight into future paths and present innovative ideas for employing Pyroptosis as a strong disease-fighting weapon.

The role and mechanism of the gut microbiota in the development and treatment of diabetic kidney disease

Diabetic kidney disease (DKD) is a common complication in patients with diabetes mellitus (DM). Increasing evidence suggested that the gut microbiota participates in the progression of DKD, which is involved in insulin resistance, renin-angiotensin system (RAS) activation, oxidative stress, inflammation and immunity. Gut microbiota-targeted therapies including dietary fiber, supplementation with probiotics or prebiotics, fecal microbiota transplantation and diabetic agents that modulate the gut microbiota, such as metformin, glucagon-like peptide-1 (GLP-1) receptor agonists, dipeptidyl peptidase-4 (DPP-4) inhibitors, and sodium-glucose transporter-2 (SGLT-2) inhibitors. In this review, we summarize the most important findings about the role of the gut microbiota in the pathogenesis of DKD and the application of gut microbiota-targeted therapies.

Modulation of P2X4 receptor activity by ivermectin and 5-BDBD has no effect on the development of ARPKD in PCK rats

Autosomal recessive polycystic kidney disease (ARPKD) is an inherited pathology caused mainly by mutations of the polycystic kidney and hepatic disease 1 (PKHD1) gene, which usually leads to end-stage renal disease. Previous studies suggested that the P2X purinoreceptor 4 (P2X4 R) may play an important role in the progression of ARPKD. To test this hypothesis, we assessed the chronic effects of ivermectin (P2X4 R allosteric modulator) and 5-BDBD (P2X4 R antagonist) on the development of ARPKD in PCK/CrljCrl-Pkhd1pck/CRL (PCK) rats. Our data indicated that activation of ATP-mediated P2X4 R signaling with ivermectin for 6 weeks in high dose (50 mg/L; water supplementation) decreased the total body weight of PCK rats while the heart and kidney weight remained unaffected. Smaller doses of ivermectin (0.5 or 5 mg/L, 6 weeks) or the inhibition of P2X4 R signaling with 5-BDBD (18 mg/kg/day, food supplement for 8 weeks) showed no effect on electrolyte balance or the basic physiological parameters. Furthermore, cystic index analysis for kidneys and liver revealed no effect of smaller doses of ivermectin (0.5 or 5 mg/L) and 5-BDBD on the cyst development of PCK rats. We observed a slight increase in the cystic liver index on high ivermectin dose, possibly due to the cytotoxicity of the drug. In conclusion, this study revealed that pharmacological modulation of P2X4 R by ivermectin or 5-BDBD does not affect the development of ARPKD in PCK rats, which may provide insights for future studies on investigating the therapeutic potential of adenosine triphosphate (ATP)-P2 signaling in PKD diseases.

Ion channels as a therapeutic target for renal fibrosis

Renal ion channel transport and electrolyte disturbances play an important role in the process of functional impairment and fibrosis in the kidney. It is well known that there are limited effective drugs for the treatment of renal fibrosis, and since a large number of ion channels are involved in the renal fibrosis process, understanding the mechanisms of ion channel transport and the complex network of signaling cascades between them is essential to identify potential therapeutic approaches to slow down renal fibrosis. This review summarizes the current work of ion channels in renal fibrosis. We pay close attention to the effect of cystic fibrosis transmembrane conductance regulator (CFTR), transmembrane Member 16A (TMEM16A) and other Cl− channel mediated signaling pathways and ion concentrations on fibrosis, as well as the various complex mechanisms for the action of Ca2+ handling channels including Ca2+-release-activated Ca2+ channel (CRAC), purinergic receptor, and transient receptor potential (TRP) channels. Furthermore, we also focus on the contribution of Na+ transport such as epithelial sodium channel (ENaC), Na+, K+-ATPase, Na+-H+ exchangers, and K+ channels like Ca2+-activated K+ channels, voltage-dependent K+ channel, ATP-sensitive K+ channels on renal fibrosis. Proposed potential therapeutic approaches through further dissection of these mechanisms may provide new therapeutic opportunities to reduce the burden of chronic kidney disease.

Does Pyroptosis Play a Role in Inflammasome-Related Disorders?

Inflammasomes are multiprotein complexes orchestrating intracellular recognition of endogenous and exogenous stimuli, cellular homeostasis, and cell death. Upon sensing of certain stimuli, inflammasomes typically activate inflammatory caspases that promote the production and release of the proinflammatory cytokines IL-1β, IL-1α, and IL-18 and induce a type of inflammatory cell death known as “pyroptosis”. Pyroptosis is an important form of regulated cell death executed by gasdermin proteins, which is largely different from apoptosis and necrosis. Recently, several signaling pathways driving pyroptotic cell death, including canonical and noncanonical inflammasome activation, as well as caspase-3-dependent pathways, have been reported. While much evidence exists that pyroptosis is involved in the development of several inflammatory diseases, its contribution to inflammasome-related disorders (IRDs) has not been fully clarified. This article reviews molecular mechanisms leading to pyroptosis, and attempts to provide evidence for its possible role in inflammasome-related disorders, including NLR pyrin domain containing 3 (NLRP3) inflammasome disease, NLR containing a caspase recruitment domain 4 (NLRC4) inflammasome disease, and pyrin inflammasome disease. Although the specific mechanism needs further investigations, these studies have uncovered the role of pyroptosis in inflammasome-related disorders and may open new avenues for future therapeutic interventions.

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

The pharmacological blockade of P2X4 receptors has shown potential benefits in the management of several immune/inflammatory diseases. However, data regarding the involvement of P2X4 receptors in the pathophysiological mechanisms of action in intestinal inflammation are not well defined. We aimed to evaluate the anti-inflammatory effects of two novel and selective P2X4 receptor antagonists, NC-2600 and NP-1815-PX, and characterize the molecular mechanisms of their action in a murine model of 2,4-dinitrobenzene sulfonic acid (DNBS)-induced colitis. These two drugs and dexamethasone (DEX) were administered orally for 6 days, immediately after the manifestation of DNBS. The body weight decrease, resulting from colitis, was attenuated by NC-2600 and NP-1815-PX, but not DEX. However, all three drugs attenuated the increase in spleen weight and ameliorated macroscopic and microscopic colonic tissue damage. Furthermore, all three compounds decreased tissue IL-1β levels and caspase-1 expression and activity. Colonic tissue increase of tumor necrosis factor was downregulated by DEX, while both NC-2600 and NP-1815-PX were ineffective. The reduction of occludin associated with colitis was ameliorated by NC-2600 and NP-1815-PX, but not DEX. In THP-1 cells, lipopolysaccharide and ATP upregulated IL-1β release and NLRP3, caspase-1, caspase-5, and caspase-8 activity, but not of caspase-4. These changes were prevented by NC-2600 and NP-1815-PX treatment. For the first time, the above findings show that the selective inhibition of P2X4 receptors represents a viable approach to manage bowel inflammation via the inhibition of NLRP3 inflammasome signaling pathways.

Insights into the Uses of Traditional Plants for Diabetes Nephropathy: A Review

Diabetic nephropathy (DN) is a serious kidney illness characterized by proteinuria, glomerular enlargement, reduced glomerular filtration, and renal fibrosis. DN is the most common cause of end-stage kidney disease, accounting for nearly one-third of all cases of diabetes worldwide. Hyperglycemia is a major factor in the onset and progression of diabetic nephropathy. Many contemporary medicines are derived from plants since they have therapeutic properties and are relatively free of adverse effects. Glycosides, alkaloids, terpenoids, and flavonoids are among the few chemical compounds found in plants that are utilized to treat diabetic nephropathy. The purpose of this review was to consolidate information on the clinical and pharmacological evidence supporting the use of a variety of medicinal plants to treat diabetic nephropathy.

Blocking P2X purinoceptor 4 signalling alleviates cigarette smoke induced pulmonary inflammation

Background

Chronic obstructive pulmonary disease (COPD) is associated with elevated ATP levels in the extracellular space. Once released, ATP serves as danger signal modulating immune responses by activating purinergic receptors. Accordingly, purinergic signalling has been implicated in respiratory inflammation associated with cigarette smoke exposure. However, the role of P2X4-signalling has not been fully elucidated yet.

Methods

Here, we analysed the P2X4 mRNA expression in COPD patients as well as cigarette smoke-exposed mice. Furthermore, P2X4-signalling was blocked by either using a specific antagonist or genetic depletion of P2rx4 in mice applied to an acute and prolonged model of cigarette smoke exposure. Finally, we inhibited P2X4-signalling in macrophages derived from THP-1 before stimulation with cigarette smoke extract.

Results

COPD patients exhibited an increased P2X4 mRNA expression in cells isolated from the bronchoalveolar lavage fluid and peripheral mononuclear cells. Similarly, P2rx4 expression was elevated in lung tissue of mice exposed to cigarette smoke. Blocking P2X4-signalling in mice alleviated cigarette smoke induced airway inflammation as well as lung parenchyma destruction. Additionally, human macrophages derived from THP-1 cells released reduced concentrations of proinflammatory cytokines in response to cigarette smoke extract stimulation when P2X4 was inhibited.

Conclusion

Taken together, we provide evidence that P2X4-signalling promotes innate immunity in the immunopathologic responses induced by cigarette smoke exposure.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02072-z.

A ketogenic diet reduces mechanical allodynia and improves epidermal innervation in diabetic mice

ABSTRACT

Dietary interventions are promising approaches to treat pain associated with metabolic changes because they impact both metabolic and neural components contributing to painful neuropathy. Here, we tested whether consumption of a ketogenic diet could affect sensation, pain, and epidermal innervation loss in type 1 diabetic mice. C57Bl/6 mice were rendered diabetic using streptozotocin and administered a ketogenic diet at either 3 weeks (prevention) or 9 weeks (reversal) of uncontrolled diabetes. We quantified changes in metabolic biomarkers, sensory thresholds, and epidermal innervation to assess impact on neuropathy parameters. Diabetic mice consuming a ketogenic diet had normalized weight gain, reduced blood glucose, elevated blood ketones, and reduced hemoglobin-A1C levels. These metabolic biomarkers were also improved after 9 weeks of diabetes followed by 4 weeks of a ketogenic diet. Diabetic mice fed a control chow diet developed rapid mechanical allodynia of the hind paw that was reversed within a week of consumption of a ketogenic diet in both prevention and reversal studies. Loss of thermal sensation was also improved by consumption of a ketogenic diet through normalized thermal thresholds. Finally, diabetic mice consuming a ketogenic diet had normalized epidermal innervation, including after 9 weeks of uncontrolled diabetes and 4 weeks of consumption of the ketogenic diet. These results suggest that, in mice, a ketogenic diet can prevent and reverse changes in key metabolic biomarkers, altered sensation, pain, and axon innervation of the skin. These results identify a ketogenic diet as a potential therapeutic intervention for patients with painful diabetic neuropathy and/or epidermal axon loss.

Novel insights into NOD-like receptors in renal diseases

Nucleotide-binding oligomerization domain-like receptors (NLRs), including NLRAs, NLRBs (also known as NAIPs), NLRCs, and NLRPs, are a major subfamily of pattern recognition receptors (PRRs). Owing to a recent surge in research, NLRs have gained considerable attention due to their involvement in mediating the innate immune response and perpetuating inflammatory pathways, which is a central phenomenon in the pathogenesis of multiple diseases, including renal diseases. NLRs are expressed in different renal tissues during pathological conditions, which suggest that these receptors play roles in acute kidney injury, obstructive nephropathy, diabetic nephropathy, IgA nephropathy, lupus nephritis, crystal nephropathy, uric acid nephropathy, and renal cell carcinoma, among others. This review summarises recent progress on the functions of NLRs and their mechanisms in the pathophysiological processes of different types of renal diseases to help us better understand the role of NLRs in the kidney and provide a theoretical basis for NLR-targeted therapy for renal diseases.

PM2.5 exposure inducing ATP alteration links with NLRP3 inflammasome activation

Fine particulate matter (PM_2.5) has been the primary air pollutant and the fourth leading risk factor for disease and death in the world. Exposure to PM_2.5 is related to activation of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, but the mechanism of PM_2.5 affecting the NLRP3 inflammasome is still unclear. Previous studies have shown that PM_2.5 can cause alterations in adenosine triphosphate (ATP), and an increase in extracellular ATP and a decrease in intracellular ATP can trigger the activation process of the NLRP3 inflammasome. Therefore, we emphasize that ATP changes may be the central link and key mechanism of PM_2.5 exposure that activates the NLRP3 inflammasome. This review briefly elucidates and summarizes how PM_2.5 acts on ATP and subsequently further impacts the NLRP3 inflammasome. Investigation of ATP changes due to exposure to PM_2.5 may be essential to regulate NLRP3 inflammasome activation and treat inflammation-related diseases such as coronavirus disease 2019 (COVID-19).

Motoneuronal inflammasome activation triggers excessive neuroinflammation and impedes regeneration after sciatic nerve injury

Background

Peripheral nerve injuries are accompanied by inflammatory reactions, over-activation of which may hinder recovery. Among pro-inflammatory pathways, inflammasomes are one of the most potent, leading to release of active IL-1β. Our aim was to understand how inflammasomes participate in central inflammatory reactions accompanying peripheral nerve injury.

Methods

After axotomy of the sciatic nerve, priming and activation of the NLRP3 inflammasome was examined in cells of the spinal cord. Regeneration of the nerve was evaluated after coaptation using sciatic functional index measurements and retrograde tracing.

Results

In the first 3 days after the injury, elements of the NLRP3 inflammasome were markedly upregulated in the L4–L5 segments of the spinal cord, followed by assembly of the inflammasome and secretion of active IL-1β. Although glial cells are traditionally viewed as initiators of neuroinflammation, in this acute phase of inflammation, inflammasome activation was found exclusively in affected motoneurons of the ventral horn in our model. This process was significantly inhibited by 5-BDBD, a P2X4 receptor inhibitor and MCC950, a potent NLRP3 inhibitor. Although at later time points the NLRP3 protein was upregulated in microglia too, no signs of inflammasome activation were detected in these cells. Inhibition of inflammasome activation in motoneurons in the first days after nerve injury hindered development of microgliosis in the spinal cord. Moreover, P2X4 or inflammasome inhibition in the acute phase significantly enhanced nerve regeneration on both the morphological and the functional levels.

Conclusions

Our results indicate that the central reaction initiated by sciatic nerve injury starts with inflammasome activation in motoneurons of the ventral horn, which triggers a complex inflammatory reaction and activation of microglia. Inhibition of neuronal inflammasome activation not only leads to a significant reduction of microgliosis, but has a beneficial effect on the recovery as well.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02427-9.

Spop ameliorates diabetic nephropathy through restraining NLRP3 inflammasome

Diabetic nephropathy (DN) is one of the most common causes for end-stage renal disease without effective therapies available. NLR family, pyrin domain-containing 3 (NLRP3) inflammasome possesses a fundamental effect to facilitate the pathogenesis of DN. Unfortunately, how NLRP3 inflammasome is mediated still remains largely unclear. In the present study, an E3 ubiquitin ligase Speckle-type BTB-POZ protein (Spop) was identified as a suppressor of NLRP3 inflammasome. We first showed that Spop expression was extensively down-regulated in kidney of DN patients, which was confirmed in kidney of streptozotocin (STZ)-challenged mice and in high glucose (HG)-stimulated podocytes. Intriguingly, we showed that conditional knockout (cKO) of Spop in podocytes considerably accelerated renal dysfunction and pathological changes in the glomerulus of STZ-induced mice with DN, along with severe podocyte injury. Furthermore, Spop specific ablation in podocytes dramatically facilitated inflammatory response in glomeruli of DN mice via enhancing NLRP3 inflammasome and nuclear factor κB (NF-κB) signaling pathways, which were confirmed in HG-cultured podocytes. Notably, our findings indicated that Spop directly interacted with NLRP3. More importantly, Spop promoted NLRP3 degradation via elevating K48-linked polyubiquitination of NLRP3. Collectively, our findings disclosed a mechanisms through which Spop limited NLRP3 inflammasome under HG condition, and illustrated that Spop may be a novel therapeutic target to suppress NLRP3 inflammasome, contributing to the DN management.

P2X4 deficiency reduces atherosclerosis and plaque inflammation in mice

Extracellular adenosine-5′-triphosphate (ATP) acts as an import signaling molecule mediating inflammation via purinergic P2 receptors. ATP binds to the purinergic receptor P2X₄ and promotes inflammation via increased expression of pro-inflammatory cytokines. Because of the central role of inflammation, we assumed a functional contribution of the ATP-P2X₄-axis in atherosclerosis. Expression of P2X₄ was increased in atherosclerotic aortic arches from low-density lipoprotein receptor-deficient mice being fed a high cholesterol diet as assessed by real-time polymerase chain reaction and immunohistochemistry. To investigate the functional role of P2X₄ in atherosclerosis, P2X₄-deficient mice were crossed with low-density lipoprotein receptor-deficient mice and fed high cholesterol diet. After 16 weeks, P2X₄-deficient mice developed smaller atherosclerotic lesions compared to P2X₄-competent mice. Furthermore, intravital microscopy showed reduced ATP-induced leukocyte rolling at the vessel wall in P2X₄-deficient mice. Mechanistically, we found a reduced RNA expression of CC chemokine ligand 2 (CCL-2), C-X-C motif chemokine-1 (CXCL-1), C-X-C motif chemokine-2 (CXCL-2), Interleukin-6 (IL-6) and tumor necrosis factor α (TNFα) as well as a decreased nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3)-inflammasome priming in atherosclerotic plaques from P2X₄-deficient mice. Moreover, bone marrow derived macrophages isolated from P2X₄-deficient mice revealed a reduced ATP-mediated release of CCL-2, CC chemokine ligand 5 (CCL-5), Interleukin-1β (IL-1β) and IL-6. Additionally, P2X₄-deficient mice shared a lower proportion of pro-inflammatory Ly6C^high monocytes and a higher proportion of anti-inflammatory Ly6C^low monocytes, and expressend less endothelial VCAM-1. Finally, increased P2X₄ expression in human atherosclerotic lesions from carotid endarterectomy was found, indicating the importance of potential implementations of this study’s findings for human atherosclerosis. Collectively, P2X₄ deficiency reduced experimental atherosclerosis, plaque inflammation and inflammasome priming, pointing to P2X₄ as a potential therapeutic target in the fight against atherosclerosis.

The mechanism by which ATP regulates alcoholic steatohepatitis through P2X4 and CD39

Alcoholic liver disease caused by chronic excessive drinking has become one of the most common types of liver disease. Alcohol-induced inflammatory immune responses play a central role in the development of alcohol-associated steatohepatitis. The content and expression of ATP and P2X4 in the livers of alcoholic steatohepatitis mice are significantly increased. The content of ATP increased by 20 percent and the expression of P2X4 receptor protein was 1.3 times higher than that in the livers of normal mice. Treatment with 5-BDBD, a P2X4 receptor-specific inhibitor, significantly reduced alcohol-induced liver inflammation and lipid deposition. In RAW264.7 cell experiments, 5-BDBD inhibited the expression of P2X4 and alleviated alcohol-induced inflammation, while the CD39-specific inhibitor POM-1 reduced extracellular ATP degradation and promoted the expression of P2X4, thereby exacerbating inflammation. After treatment with 5-BDBD, P2X4 receptor protein expression decreased by 0.2 times and after treatment with POM-1, P2X4 receptor protein expression increased by 0.1 times compared to the alcohol-stimulated group. In addition, inhibition of P2X4 expression in RAW264.7 cells reduced calcium influx in RAW264.7 cells. P2X4 may induce the activation of NLRP3 inflammasomes by mediating calcium influx, thus exacerbating the inflammatory response, and inhibition of P2X4 expression can effectively block this process. Conclusion: These results suggest that the ATP-P2X4 signaling pathway promotes the inflammatory response in alcoholic steatohepatitis and that CD39 may play a protective role in regulating P2X4 expression by hydrolyzing ATP. In conclusion, the CD39 and ATP-P2X4 signaling pathways may be potential therapeutic targets for alcoholic steatohepatitis.

Role of P2X4/NLRP3 Pathway-Mediated Neuroinflammation in Perioperative Neurocognitive Disorders

Several studies have demonstrated that neuroinflammation is the key to perioperative neurocognitive disorders (PND); however, the specific mechanism postsurgery and anesthesia has not yet been fully clarified. The present study is aimed at exploring the effects of P2X4/NLRP3 signaling pathway in neuroinflammation and cognitive impairment after surgery. 12–14-month-old male C57BL/6 mice undergoing open tibial fracture surgery by sevoflurane anesthesia were administered P2X4R inhibitor 5-BDBD or saline was intraperitoneally for 3 consecutive days after surgery. Then, the animals were subjected to Morris water maze test or sacrificed to collect the hippocampus. The level of P2X4R and NLRP3 was estimated by Western blot, the activation of microglia was detected via immunohistochemistry, and the expression of TNF-α, IL-1β, and IL-6 was quantified by enzyme-linked immunosorbent assay. These results indicated that tibial surgery caused cognitive impairment, increased the expression of P2X4R and NLRP3, and aggravated the neuroinflammation and microglia activation. However, intraperitoneal injection of 5-BDBD attenuated these effects. In conclusion, these findings indicated that the P2X4/NLRP3 pathway might be involved in the pathophysiology of PND.

Comprehensive Diagnostics of Diabetic Nephropathy by Transcriptome RNA Sequencing

BACKGROUND

Diabetic nephropathy (DN) is a primary driver of end-stage renal disease. Given the heterogeneity of renal lesions and the complex mechanisms of DN, the present-day diagnostic approach remains highly controversial. We aimed to design a diagnostic model by bioinformatics methods for discriminating DN patients from normal subjects.

METHODS

In this study, transcriptome sequencing was performed on 6 clinical samples (3 from DN patients and 3 from healthy volunteers) from the Second Affiliated Hospital of Kunming Medical University. Construction of a competing endogenous RNA (ceRNA) network based on differentially expressed (DE)-mRNAs and -long noncoding RNAs (lncRNAs). Subsequently, the CytoHubba plugin was used to identify hub genes from DE-mRNAs in the ceRNA network and to perform functional enrichment analysis on them. The least absolute shrinkage and selection operator (LASSO) regression analysis was responsible for screening the diagnostic biomarkers from hub genes and assessing their diagnostic power using ROC curves. The pathways involved in hub genes were revealed by single-gene Gene Set Enrichment Analysis (GSEA). Moreover, we verified the expression levels of diagnostic biomarkers by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot.

RESULTS

A total of 10 hub genes were screened from the ceRNA network, which appeared to be associated with the viral infection, kidney development, and regulation of immune and inflammatory responses. Subsequently, LASSO regression analysis established a diagnostic model consisting of DDX58, SAMD9L, and TLR6 with a robust diagnostic potency (AUC = 1). Similarly, single-gene GSEA showed a strong association of these diagnostic biomarkers with the viral infection. Furthermore, PCR and Western blot demonstrated showed that DDX58, SAMD9L, and TLR6 were upregulated in DN patients at both transcriptome and protein levels compared to healthy controls.

CONCLUSION

We confirmed that differentially expressed hub genes may be novel diagnostic biomarkers in DN.

Purinergic P2 receptors: Involvement and therapeutic implications in diabetes-related glomerular injury

The purinergic activation of P2 receptors initiates a powerful and rapid signaling cascade that contributes to the regulation of an array of physiological and pathophysiological processes in many organs, including the kidney. P2 receptors are broadly distributed in both epithelial and vascular renal cells. Disturbances of purinergic signaling can lead to impairments in renal function. A growing body of evidence indicates changes in P2 receptor expression and nucleotide metabolism in chronic renal injury and inflammatory diseases. Increasing attention has focused on purinergic P2X7 receptors, which are not normally expressed in healthy kidney tissue but are highly expressed at sites of tissue damage and inflammation. Under hyperglycemic conditions, several mechanisms that are linked to purinergic signaling and involve nucleotide release and degradation are disrupted, resulting in the accumulation of adenosine 5'-triphosphate in the bloodstream in diabetes. Dysfunction of the purinergic system might be associated with serious vascular complications in diabetes, including diabetic nephropathy. This review summarizes our current knowledge of the role of P2 receptors in diabetes-related glomerular injury and its implications for new therapeutics for diabetic nephropathy.

The Complex Interplay between Autophagy and NLRP3 Inflammasome in Renal Diseases

Autophagy is a highly conserved process of the eukaryotic cell cycle. It plays an important role in the survival and maintenance of cells by degrading organelles, proteins, and macromolecules in the cytoplasm and the circulation of degraded products. The dysfunction of autophagy can lead to the pathology of many human diseases. The nucleotide-binding oligomerization domain-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome belongs to the family of nucleotide-binding and oligomerization domain-like receptors (NLRs) and can induce caspase-1 activation, thus leading to the maturation and secretion of interleukin-1beta (IL-1β) and IL-18. It has been reported that the interplay between autophagy and NLRP3 inflammasome is involved in many diseases, including renal diseases. In this review, the interplay between autophagy and the NLRP3 inflammasome and the mechanisms in renal diseases are explored to provide ideas for relevant basic research in the future.

The Multiple Roles of Fibroblast Growth Factor in Diabetic Nephropathy

Diabetic nephropathy (DN) is a common microvascular complication in the late stages of diabetes. Currently, the etiology and pathogenesis of DN are not well understood. Even so, available evidence shows its development is associated with metabolism, oxidative stress, cytokine interaction, genetic factors, and renal microvascular disease. Diabetic nephropathy can lead to proteinuria, edema and hypertension, among other complications. In severe cases, it can cause life-threatening complications such as renal failure. Patients with type 1 diabetes, hypertension, high protein intake, and smokers have a higher risk of developing DN. Fibroblast growth factor (FGF) regulates several human processes essential for normal development. Even though FGF has been implicated in the pathological development of DN, the underlying mechanisms are not well understood. This review summarizes the role of FGF in the development of DN. Moreover, the association of FGF with metabolism, inflammation, oxidative stress and fibrosis in the context of DN is discussed. Findings of this review are expected to deepen our understanding of DN and generate ideas for developing effective prevention and treatments for the disease.

Molecular mechanism and therapeutic targeting of necrosis, apoptosis, pyroptosis, and autophagy in cardiovascular disease

ABSTRACT

Cell death occurs in various tissues and organs in the body. It is a physiological or pathological process that has different effects. It is of great significance in maintaining the morphological function of cells and clearing abnormal cells. Pyroptosis, apoptosis, and necrosis are all modes of cell death that have been studied extensively by many experts and scholars, including studies on their effects on the liver, kidney, the heart, other organs, and even the whole body. The heart, as the most important organ of the body, should be a particular focus. This review summarizes the mechanisms underlying the various cell death modes and the relationship between the various mechanisms and heart diseases. The current research status for heart therapy is discussed from the perspective of pathogenesis.

The mechanism behind activation of the Nod-like receptor family protein 3 inflammasome in Parkinson's disease

Previous studies have shown that the ATP-P2X4 receptor signaling pathway mediates the activation of the Nod-like receptor family protein 3 (NLRP3) inflammasome. The NLRP3 inflammasome may promote renal interstitial inflammation in diabetic nephropathy. As inflammation also plays an important role in the pathogenesis of Parkinson’s disease, we hypothesized that the ATP-P2X4 receptor signaling pathway may activate the NLRP3 inflammasome in Parkinson’s disease. A male rat model of Parkinson’s disease was induced by stereotactic injection of 6-hydroxydopamine into the pars compacta of the substantia nigra. The P2X4 receptor and the NLRP3 inflammasome (interleukin-1β and interleukin-18) were activated. Intracerebroventricular injection of the selective P2X4 receptor antagonist 5-(3-bromophenyl)-1,3-dihydro-2H-benzofuro[3,2-e]-1,4-diazepin-2-one (5-BDBD) or knockdown of P2X4 receptor expression by siRNA inhibited the activation of the NLRP3 inflammasome and alleviated dopaminergic neurodegeneration and neuroinflammation. Our results suggest that the ATP-P2X4 receptor signaling pathway mediates NLRP3 inflammasome activation, dopaminergic neurodegeneration, and dopamine levels. These findings reveal a novel role of the ATP-P2X4 axis in the molecular mechanisms underlying Parkinson’s disease, thus providing a new target for treatment. This study was approved by the Animal Ethics Committee of Qingdao University, China, on March 5, 2015 (approval No. QYFYWZLL 26119).

NLRP3 Inflammasome in Metabolic-Associated Kidney Diseases: An Update

Metabolic syndrome (MS) is a group of complex metabolic disorders syndrome, which refers to the pathological state of metabolism disorder of protein, fat, carbohydrate and other substances in human body. The kidney is an important organ of metabolism, and various metabolic disorders can lead to the abnormalities in the structure and function of the kidney. The recognition of pathogenesis and treatment measures of renal damage in MS is a very important part for the renal function preserve. Inflammatory response caused by various metabolic factors is a protective mechanism of the body, but persistent inflammation will become a harmful factor and aggravate kidney damage. Inflammasomes are sensors of the innate immune system that play crucial roles in initiating inflammation in response to acute infections and chronic diseases. They are multiprotein complex composed of cytoplasmic sensors (mainly NLR family members), apoptosis-associated speck-like protein (ASC or PYCARD) and pro-caspase-1. After receiving exogenous and endogenous stimuli, the sensors begin to assemble inflammasome and then promote the release of inflammatory cytokines IL-1β and IL-18, resulting in a special way of cell death named pyroptosis. In the kidney, NLRP3 inflammasome can be activated by a variety of pathways, which eventually leads to inflammatory infiltration, renal intrinsic cell damage and renal function decline. This paper reviews the function and specific regulatory mechanism of inflammasome in kidney damage caused by various metabolic disorders, which will provide a new therapeutic perspective and targets for kidney diseases.

Characterization of purinergic receptor 2 signaling in podocytes from diabetic kidneys

Growing evidence suggests that renal purinergic signaling undergoes significant remodeling during pathophysiological conditions such as diabetes. This study examined the renal P2 receptor profile and ATP-mediated calcium response from podocytes in glomeruli from kidneys with type 1 or type 2 diabetic kidney disease (DKD), using type 2 diabetic nephropathy (T2DN) rats and streptozotocin-injected Dahl salt-sensitive (type 1 diabetes) rats. A dramatic increase in the ATP-mediated intracellular calcium flux in podocytes was observed in both models. Pharmacological inhibition established that P2X₄ and P2X₇ are the major receptors contributing to the augmented ATP-mediated intracellular calcium signaling in diabetic podocytes. The transition in purinergic receptor composition from metabotropic to ionotropic may disrupt intracellular calcium homeostasis in podocytes resulting in their dysfunction and potentially further aggravating DKD progression.

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Diabetic podocytes have sustained intracellular Ca²⁺ signaling in response to ATP

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Podocyte purinergic receptor signaling is predominantly ionotropic in diabetes

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Both type 1 and 2 diabetic podocytes have similar purinergic receptor remodeling

Advances in understanding the innate immune-associated diabetic kidney disease

Millions of human deaths occur annually due to chronic kidney disease, caused by diabetic kidney disease (DKD). Despite having effective drugs controlling the hyperglycemia and high blood pressure, the incidence of DKD is increasing, which indicates the need for the development of novel therapies to control DKD. In this article, we discussed the recent advancements in the basic innate immune mechanisms in renal tissues triggered under the diabetes environment, leading to the pathogenesis and progression of DKD. We also summarized the currently available innate immune molecules-targeting therapies tested against DKD in clinical and preclinical settings, and highlighted additional drug targets that could potentially be employed for the treatment of DKD. The improved understanding of the disease pathogenesis may open avenues for the development of novel therapies to rein in DKD, which consequently, can reduce morbidity and mortality in humans in the future.

Caspase-1-Inhibitor AC-YVAD-CMK Inhibits Pyroptosis and Ameliorates Acute Kidney Injury in a Model of Sepsis

Objective

To observe the protective effect of AC-YVAD-CMK on sepsis-induced acute kidney injury in mice and to explore its possible mechanisms primarily.

Methods

Eighteen male C57BL/6 mice were randomly divided into sham-operated group (Control), cecal ligation and puncture group (CLP), and CLP model treated with AC-YVAD-CMK group (AC-YVAD-CMK) (n = 6 in each group). Mice were sacrificed at 24 h after operation, and blood and kidney tissue samples were collected for analyses. Histologic changes were determined microscopically following HE staining. The expression of Ly-6B and CD68 was investigated using immunohistochemistry. Serum concentrations of creatinine (sCR) and blood urea nitrogen (BUN) were measured. Serum levels of interleukin-1β (IL-1β), interleukin-18 (IL-18), TNF-α, and interleukin-6 (IL-6) were determined by ELISA. The expressions of Caspas-1, NLRP-1, IL-1β, and IL-18 in renal tissues were investigated using Western blot. Immunofluorescence staining was used to detect the expression of GSDMD protein in renal tissues.

Results

AC-YVAD-CMK treatment significantly alleviates sepsis-induced acute kidney injury, with decreased histological injury in renal tissues, suppresses the accumulation of neutrophils and macrophages in renal tissues, and decreased sCR and BUN level (P < 0.05). Attenuation of sepsis-induced acute kidney injury was due to the prohibited production of inflammatory cytokines and decrease expression of Caspas-1, NLRP-1, IL-1β, and IL-18 in renal tissues. In addition, AC-YVAD-CMK treatment significantly reduced the expression of GSDMD in renal tissues compared to those observed in controls (P < 0.05).

Conclusions

We demonstrated a marked renoprotective effect of caspase-1-inhibitor AC-YVAD-CMK in a rat model of sepsis by inhibition of pyroptosis.

CD36 promotes NLRP3 inflammasome activation via the mtROS pathway in renal tubular epithelial cells of diabetic kidneys

Tubulointerstitial inflammation plays a key role in the pathogenesis of diabetic nephropathy (DN). Interleukin-1β (IL-1β) is the key proinflammatory cytokine associated with tubulointerstitial inflammation. The NLRP3 inflammasome regulates IL-1β activation and secretion. Reactive oxygen species (ROS) represents the main mediator of NLRP3 inflammasome activation. We previously reported that CD36, a class B scavenger receptor, mediates ROS production in DN. Here, we determined whether CD36 is involved in NLRP3 inflammasome activation and explored the underlying mechanisms. We observed that high glucose induced-NLRP3 inflammasome activation mediate IL-1β secretion, caspase-1 activation, and apoptosis in HK-2 cells. In addition, the levels of CD36, NLRP3, and IL-1β expression (protein and mRNA) were all significantly increased under high glucose conditions. CD36 knockdown resulted in decreased NLRP3 activation and IL-1β secretion. CD36 knockdown or the addition of MitoTempo significantly inhibited ROS production in HK-2 cells. CD36 overexpression enhanced NLRP3 activation, which was reduced by MitoTempo. High glucose levels induced a change in the metabolism of HK-2 cells from fatty acid oxidation (FAO) to glycolysis, which promoted mitochondrial ROS (mtROS) production after 72 h. CD36 knockdown increased the level of AMP-activated protein kinase (AMPK) activity and mitochondrial FAO, which was accompanied by the inhibition of NLRP3 and IL-1β. The in vivo experimental results indicate that an inhibition of CD36 could protect diabetic db/db mice from tubulointerstitial inflammation and tubular epithelial cell apoptosis. CD36 mediates mtROS production and NLRP3 inflammasome activation in db/db mice. CD36 inhibition upregulated the level of FAO-related enzymes and AMPK activity in db/db mice. These results suggest that NLRP3 inflammasome activation is mediated by CD36 in renal tubular epithelial cells in DN, which suppresses mitochondrial FAO and stimulates mtROS production.

Role of microglia and P2X4 receptors in chronic pain

This study summarizes current understanding of the role of microglia and P2X4 receptor in chronic pain including neuropathic pain and of their therapeutic potential.

Pain plays an indispensable role as an alarm system to protect us from dangers or injuries. However, neuropathic pain, a debilitating pain condition caused by damage to the nervous system, persists for a long period even in the absence of dangerous stimuli or after injuries have healed. In this condition, pain becomes a disease itself rather than the alarm system and is often resistant to currently available medications. A growing body of evidence indicates that microglia, a type of macrophages residing in the central nervous system, play a crucial role in the pathogenesis of neuropathic pain. Whenever microglia in the spinal cord detect a damaging signal within the nervous system, they become activated and cause diverse alterations that change neural excitability, leading to the development of neuropathic pain. For over a decade, several lines of molecular and cellular mechanisms that define microglial activation and subsequently altered pain transmission have been proposed. In particular, P2X4 receptors (a subtype of purinergic receptors) expressed by microglia have been investigated as an essential molecule for neuropathic pain. In this review article, we describe our understanding of the mechanisms by which activated microglia cause neuropathic pain through P2X4 receptors, their involvement in several pathological contexts, and recent efforts to develop new drugs targeting microglia and P2X4 receptors.

The complement system drives local inflammatory tissue priming by metabolic reprogramming of synovial fibroblasts

Arthritis typically involves recurrence and progressive worsening at specific predilection sites, but the checkpoints between remission and persistence remain unknown. Here, we defined the molecular and cellular mechanisms of this inflammation-mediated tissue priming. Re-exposure to inflammatory stimuli caused aggravated arthritis in rodent models. Tissue priming developed locally and independently of adaptive immunity. Repeatedly stimulated primed synovial fibroblasts (SFs) exhibited enhanced metabolic activity inducing functional changes with intensified migration, invasiveness and osteoclastogenesis. Meanwhile, human SF from patients with established arthritis displayed a similar primed phenotype. Transcriptomic and epigenomic analyses as well as genetic and pharmacological targeting demonstrated that inflammatory tissue priming relies on intracellular complement C3- and C3a receptor-activation and downstream mammalian target of rapamycin- and hypoxia-inducible factor 1α-mediated metabolic SF invigoration that prevents activation-induced senescence, enhances NLRP3 inflammasome activity, and in consequence sensitizes tissue for inflammation. Our study suggests possibilities for therapeutic intervention abrogating tissue priming without immunosuppression.