Ozone exposure promotes pyroptosis in rat lungs via the TLR2/4-NF-κB-NLRP3 signaling pathway

The role of pyroptosis in environmental pollutants-induced multisystem toxicities

The global ecosystem is adversely affected by environmental pollutants, which have numerous deleterious consequences on both the environment and human health. A multitude of human organs and systems, including the neurological, digestive, cardiovascular, reproductive, and respiratory systems, can be adversely affected by these pollutants. Pyroptosis is a form of programmed cell death, primarily involving the Caspase-1/Gasdermin D (GSDMD) classical inflammasome pathway, Caspase-4/5/11/GSDMD non-classical inflammasome pathway, Caspase-3/8 pathway, and other signaling pathways, which induce cell death and regulate the occurrence of inflammatory responses. Pyroptosis plays an important role in a range of diseases, including cancer, neurodegenerative diseases and cardiovascular disease. Evidence has emerged in recent years indicating that environmental pollutants exert various toxic effects by modulating pyroptosis. In this review, we examine hepatotoxicity, cardiovascular toxicity, nephrotoxicity, neurotoxicity, pulmonary toxicity, reproductive toxicity and the related mechanisms caused by environmental pollutants through the regulation of pyroptosis. We aim to provide theoretical references for future toxicity research on environmental pollutants.

Disulfiram alleviates epithelial barrier disruption in ozone-induced chronic obstructive pulmonary disease mouse models via inhibiting Gasdermin D-mediated pyroptosis

BACKGROUND

Gasdermin D (GSDMD)-mediated pyroptosis drives inflammatory cytokine release in response to environmental triggers. Disulfiram (DSF), an FDA-approved anti-alcoholism drug, has been demonstrated to inhibit GSDMD pore formation. Although airway epithelial barrier dysfunction contributes to chronic obstructive pulmonary disease (COPD) progression, the role of GSDMD-dependent pyroptosis in ozone-induced pathogenesis, and the potential of DSF to inhibit this process, remain unexplored.

METHODS

We analyzed the expression levels of pyroptosis-related molecules in airway epithelial cells from COPD patients' samples obtained from the Gene Expression Omnibus (GEO) database and evaluated the potential therapeutic effects of DSF in a mouse model of COPD induced by chronic ozone exposure.

RESULTS

GSDMD was significantly upregulated in the airway epithelial cells of COPD patients. Chronic ozone exposure in mice elevated the cleaved form of GSDMD and reduced the expression of epithelial junctional proteins. DSF treatment effectively inhibited GSDMD-mediated pyroptosis and attenuated epithelial barrier disruption, leading to significant improvements in airway inflammation and lung function in both large and small airways. Furthermore, Gsdmd expression was negatively correlated with the tight junction protein Occludin and pulmonary function indices, including the ratio of FEV25 to FVC and MMEF.

CONCLUSION

Collectively, these findings revealed the role of GSDMD-mediated pyroptosis in epithelial barrier disruption of COPD and the potential application of DSF in the treatment of COPD.

NLRP3 Inflammasome-mediated pyroptosis in acute lung injury: Roles of main lung cell types and therapeutic perspectives

The NLRP3 inflammasome plays a pivotal role in the pathogenesis of acute lung injury (ALI) by regulating pyroptosis, a highly inflammatory form of programmed cell death. NLRP3-mediated pyroptosis leads to alveolar epithelial cell injury, increased pulmonary microvascular endothelial permeability, excessive alveolar macrophage activation, and neutrophil dysfunction, collectively driving ALI progression. In addition to the classical NLRP3-dependent pathway, the non-canonical pyroptosis pathway (caspase-4/5/11) also contributes to ALI by inducing pyroptotic cell death in AECs and ECs, further amplifying NLRP3 activation through damage-associated molecular patterns (DAMP) release. Moreover, neutrophils (NE) pyroptosis exhibits dual roles in ALI, as it enhances pathogen clearance but also exacerbates excessive inflammation and tissue damage, highlighting the complexity of its regulation. Targeting the NLRP3 inflammasome and pyroptotic pathways has emerged as a promising therapeutic strategy for ALI. Various NLRP3 inhibitors (e.g., MCC950, CY-09, OLT1177) and pyroptosis inhibitors have demonstrated significant anti-inflammatory and tissue-protective effects in preclinical models. However, the clinical translation of NLRP3-targeted therapies remains challenging due to off-target effects, potential immunosuppression, lack of patient stratification strategies, and compensatory activation of alternative inflammasomes (e.g., AIM2, NLRC4). Future studies should focus on optimizing the selectivity of NLRP3 inhibitors, developing personalized therapeutic approaches, and exploring combination strategies to enhance their clinical applicability in ALI.

Potential Impact of Climate Change-Induced Alterations on Pyroptotic Cell Death in Animal Cells: A Review

Climate change-induced alterations in temperature variation, ozone exposure, water salinity and acidification, and hypoxia might influence immunity and thus survival in diverse groups of animals from fish to mammals. Pyroptosis is a type of lytic pro-inflammatory programmed cell death, which participates in the innate immune response, and is involved in multiple diseases characterized by inflammation and cell death, mostly studied in human cells. Diverse extrinsic factors can induce pyroptosis, leading to the extracellular release of pro-inflammatory molecules such as IL-18. Climate change-related factors, either directly or indirectly, can also promote animal cell death via different regulated mechanisms, impacting organismal fitness. However, pyroptosis has been relatively less studied in this context compared to another cell death process, apoptosis. This review covers previous research pointing to the potential impact of climate change, through various abiotic stressors, on pyroptotic cell death in different animal cells in various contexts. It was proposed that temperature, ozone exposure, water salinity, water acidification and hypoxia have the potential to induce pyroptotic cell death in animal cells and promote inflammation, and that these pyroptotic events should be better understood to be able to mitigate the adverse effects of climate change on animal physiology and health. This is of high importance considering the increasing frequency, intensity and duration of climate-based changes in these environmental parameters, and the critical function of pyroptosis in immune responses of animals and in their predisposition to multiple diseases including cancer. Furthermore, the need for further mechanistic studies showing the more direct impact of climate change-induced environmental alterations on pyroptotic cell death in animals at the organismal level was highlighted. A complete picture of the association between climate change and pyroptosis in animals will be also highly valuable in terms of ecological and clinical applications, and it requires an interdisciplinary approach. SIGNIFICANCE: Climate change-induced alterations might influence animal physiology. Pyroptosis is a form of cell death with pro-inflammatory characteristics. Previous research suggests that temperature variation, ozone exposure, water salinity and acidification, and hypoxia might have the potential to contribute to pyroptotic cell death in certain cell types and contexts. Climate change-induced pyroptotic cell death should be better understood to be able to mitigate the adverse effects of climate change on animal health.

Ozone-induced lung injury and inflammation: Pathways and therapeutic targets for pulmonary diseases caused by air pollutants

Exposure to ambient Ozone (O3) air pollution directly causes by its oxidative properties, respiratory epithelial cell injury, and cell death, which promote inflammation and hyperreactivity, posing a significant public health concern. Recent clinical and experimental studies have made strides in elucidating the mechanisms underlying O3-induced epithelial cell injury, inflammation, and airway hyperreactivity, which are discussed herein. The current data suggest that O3-induced oxidative stress is a central event-inducing oxeiptotic cell death pathway. O3-induced epithelial barrier damage and cell death, triggering the release of alarmins and damage-associated molecular patterns (DAMPs), with subsequent endogenous activation of Toll-like receptors (TLRs), DNA sensing pathways, and inflammasomes, activating interleukin-1-Myd88 inflammatory pathway with the production of a range of chemokines and cytokines. This cascade orchestrates lung tissue-resident cell activation in response to O3 in leukocyte and non-leukocyte populations, driving sterile innate immune response. Chronic inflammatory response to O3, by repeated exposures, supports a mixed phenotype combining asthma and emphysema, in which their exacerbation by other particulate pollutants potentially culminates in respiratory failure. We use data from lung single-cell transcriptomics to map genes of O3-damage sensing and signaling pathways to lung cells and thereby highlight potential hotspots of O3 responses. Deeper insights into these pathological pathways might be helpful for the identification of novel therapeutic targets and strategies.

Regulated programmed cell death in sepsis associated acute lung injury: From pathogenesis to therapy

Sepsis associated acute lung injury (SALI) is a common complication in patients with severe sepsis and a disease with high morbidity and mortality in ICU patients. The main mechanism of SALI is pulmonary hypoperfusion due to hypotension and shock caused by sepsis, which leads to ischemic necrosis of alveolar endothelial cells and eventually lung failure. At present, SALI therapy mainly includes antibiotic therapy, fluid resuscitation, transfusion products and vasoactive drugs, but these strategies are not satisfactory. Therefore, focusing on the role of different cell death patterns in SALI may help in the search for effective treatments. Understanding the molecular mechanisms of SALI and identifying pathways that inhibit lung cell death are critical to developing effective drug therapies to prevent the progression of SALI. Cell death is controlled by programmed cell death (PCD) pathways, including apoptosis, necroptosis, ferroptosis, pyroptosis and autophagy. There is growing evidence that PCD plays an important role in the pathogenesis of SALI, and inhibitors of various types of PCD represent a promising therapeutic strategy. Therefore, understanding the role and mechanism of PCD in SALI is conducive to our understanding of its pathological mechanism, and is of great significance for the treatment of SALI. In this article, we discuss recent advances in the role of PCD in SALI, show how different signaling pathways (such as NF-κB, PI3K/Akt, mTOR, and Nrf2) regulate PCD to regulate SALI development, and discuss the associations between various types of PCD. The aim is to explore the molecular mechanism behind SALI and to find new targets for SALI therapy.

Physical activity alleviated associations of oxidation capacity of the atmosphere with platelet-based inflammatory indicators: findings from the Henan Rural Cohort Study

Background: several adverse effects of ozone (O3) and nitrogen dioxide (NO2) are assessed using combined oxidant capacity (Ox) and redox-weighted oxidant capacity (Owtx) as surrogates. However, the associations of oxidant capacity (Ox and Owtx) with platelet-based inflammatory indicators and the potential modifying role of physical activity (PA) remain unclear. Methods: 31 318 participants were selected from the baseline survey of the Henan Rural Cohort Study. The Ox and Owtx were calculated based on O3 and NO2. The International Physical Activity Questionnaire was used to evaluate PA. Platelet-based inflammatory indicators were obtained from the data of physical examination. Generalized linear models were applied to explore associations between atmospheric oxidation capacity indicators (O3, Ox, Owtx, and NO2) and platelet-based inflammatory indicators and whether PA modified these associations. Results: O3, Ox, and Owtx were positively associated with platelet-based inflammatory indicators (PCT, PLT, PLR, SII, MLR and SIRI). The estimated β values and 95% confidence intervals (CIs) for PLT in response to a 5 μg m-3 increment in O3, Ox, and Owtx were 19.267 × 109 L-1 (95% CI: 17.493, 21.041 × 109 L-1), 6.226 × 109 L-1 (95% CI: 5.502, 6.950 × 109 L-1), and 14.664 × 109 L-1 (95% CI: 13.101, 16.227 × 109 L-1), respectively. The corresponding values for SIRI were 0.134 × 109 L-1 (95% CI: 0.111, 0.156 × 109 L-1), 0.064 × 109 L-1 (95% CI: 0.055, 0.073 × 109 L-1), and 0.135 × 109 L-1 (95% CI: 0.115, 0.155 × 109 L-1). And similar results were observed for NO2. Furthermore, we observed positive associations of O3, Ox, Owtx, and NO2 with platelet-based inflammatory indicators attenuated by increased PA levels. Conclusions: exposure to O3, Ox, Owtx, and NO2 was positively associated with platelet-based inflammatory indicators, and these associations were modified by PA. The findings suggested that a healthy lifestyle of PA might be an effective measure against early adverse effects of air pollution.

β-Caryophyllene attenuates oxidative stress and inflammatory response in LPS induced acute lung injury by targeting ACE2/MasR and Nrf2/HO-1/NF-κB axis

Acute lung injury (ALI) and its severe form, acute respiratory distress syndrome (ARDS), is a clinical syndrome that can cause pulmonary edema, inflammation, oxidative stress, and immunological dysregulations. β-Caryophyllene (BCP), a natural bicyclic sesquiterpene, possesses a variety of pharmacological properties and has the potential to be a therapeutic agent. This study aimed to comprehend the effect of BCP on Nrf2/HO-1/NF-κB and ACE2/MasR axis in a rat model of ALI by lipopolysaccharide (LPS) and the underlying mechanisms during this process. The study also examined pulmonary edema, BALF, and cytokine production to investigate inflammation and oxidative stress. In the LPS group, Western blot analysis showed decreased Nrf2/HO-1 and ACE2/MasR, including increased lung edema, elevated vascular permeability, neutrophil infiltration in BALF, increased cytokine levels, and histological changes. In comparison to the LPS group, BCP dramatically reduced lung edema, vascular permeability, and histological changes. Additionally, by lowering malondialdehyde and myeloperoxidase activity in lung tissues, it also reduced oxidative stress. BCP boosted IL-10 production and decreased the levels of pro-inflammatory cytokines and neutrophil infiltration. BCP administration decreased VEGF-A and SP-D expression, subsequently lowering NF-κB activation and cytokine production. Further, BCP altered ACE2 expression, indicating its involvement by activating the ACE2/Angiotensin (1-7)/MasR axis. In addition, BCP could stimulate the Nrf2/HO-1 anti-oxidant axis to suppress NF-κB and reduce inflammation. BCP modulation of the ACE2/MasR and Nrf2/HO-1/NF-κB axis impedes the course of ALI by influencing immunological response including but not limited to oxidative stress, the influx of neutrophils, and cytokine production. Hence, BCP may act as a potential candidate for management of ALI.

Pyroptosis, gasdermins and allergic diseases

Pyroptosis is an inflammatory form of programmed cell death that is distinct from necrosis and apoptosis. Pyroptosis is primarily mediated by the gasdermin family of proteins (GSDMA-E and PVJK), which, when activated by proteolytic cleavage, form pores in the plasma membrane, leading to cell death. While much of the past research on pyroptosis has focused on its role in cancer, metabolic disorders, and infectious diseases, recent experimental and observational studies have begun to implicate pyroptosis in allergic diseases. These studies suggest that gasdermin-mediated pyroptosis contributes to the development of allergic conditions and could offer novel targets for therapy. Here, we review our current understanding of pyroptosis with an emphasis on the role of gasdermins as executioners of pyroptosis and potential mediators to allergic disease. We highlight new discoveries that establish a mechanistic link between the biochemical actions of gasdermins and the onset of allergic diseases. Additionally, we discuss how pyroptosis and gasdermins might contribute to the dysfunction of epithelial barrier, a key factor believed to initiate the progression of various allergic diseases.

Pharmacological Inhibition or Silencing of TREM1 Restrains HCC Cell Metastasis by Inactivating TLR/PI3K/AKT Signaling

Hepatocellular carcinoma (HCC), a widely prevalent malignancy strongly linked to inflammation, remains a significant public health concern. Triggering receptor expressed on myeloid cells 1 (TREM1), a modulator of inflammatory responses identified in recent years, has emerged as a crucial facilitator in cancer progression. Despite its significance, the precise regulatory mechanism of TREM1 in HCC metastasis remains unanswered. In the present investigation, we observed aberrant upregulation of TREM1 in HCC tissues, which was significantly linked to poorer overall survival. Inhibition of TREM1 expression resulted in a significant reduction in HCC Huh-7 and MHCC-97H cell proliferation, invasion, and epithelial-mesenchymal transition (EMT) process. Furthermore, inhibiting TREM1 decreased protein expressions of toll-like receptor 2/4 (TLR2/4) and major myeloid differentiation response gene 88 (MyD88), leading to the inactivation of phosphatidylinositol 3-kinase (PI3K) and protein kinase B (AKT) in HCC cells. Notably, these effects were reversed by treatment with TLR2-specific agonist (CU-T12-9), indicating a potential crosstalk between TREM1 and TLR2/4. Mechanistic studies revealed a direct interaction between TREM1 and both TLR2 and TLR4. In vivo studies demonstrated that inhibition of TREM1 suppressed the growth of HCC cells in the orthotopic implant model and its metastatic potential in the experimental lung metastasis model. Overall, our findings underscore the role of TREM1 inhibition in regulating EMT and metastasis of HCC cells by inactivating the TLR/PI3K/AKT signaling pathway, thereby providing deeper mechanistic insights into how TREM1 regulates metastasis during HCC progression.

GDF11 protects against mitochondrial-dysfunction-dependent NLRP3 inflammasome activation to attenuate osteoarthritis

INTRODUCTION

Osteoarthritis (OA) is a highly prevalent degenerative disease worldwide, and tumor necrosis factor (TNF-α) is closely associated with its development. Growth differentiation factor 11 (GDF11) has demonstrated anti-injury and anti-aging abilities in certain tissues; however, its regulatory role in OA remains unclear and requires further investigation.

OBJECTIVES

To identify whether GDF11 can attenuate osteoarthritis. To exploring the the potential mechanism of GDF11 in alleviating osteoarthritis.

METHODS

In this study, we cultured and stimulated mouse primary chondrocytes with or without TNF-α, analyzing the resulting damage phenotype through microarray analysis. Additionally, we employed GDF11 conditional knockout mice OA model to examine the relationship between GDF11 and OA. To investigate the target of GDF11's function, we utilized NLRP3 knockout mice and its inhibitor to verify the potential involvement of the NLRP3 inflammasome.

RESULTS

Our in vitro experiments demonstrated that endogenous overexpression of GDF11 significantly inhibited TNF-α-induced cartilage matrix degradation and inflammatory expression in chondrocytes. Furthermore, loss of GDF11 led to NLRP3 inflammasome activation, inflammation, and metabolic dysfunction. In an in vivo surgically induced mouse model, intraarticular administration of recombinant human GDF11 alleviated OA pathogenesis, whereas GDF11 conditional knockout reversed this effect. Additionally, findings from the NLRP3-knockout DMM mouse model revealed that GDF11 exerted its protective effect by inhibiting NLRP3.

CONCLUSION

These findings demonstrate the ability of GDF11 to suppress TNF-α-induced inflammation and cartilage degeneration by preventing mitochondrial dysfunction and inhibiting NLRP3 inflammasome activation, suggesting its potential as a promising therapeutic drug for osteoarthritis.

SIRT1 alleviates Cd nephrotoxicity through NF-κB/p65 deacetylation-mediated pyroptosis in rat renal tubular epithelial cells

Cadmium (Cd) is a widely distributed environmental pollutant, primarily causing nephrotoxicity through renal proximal tubular cell impairment. Pyroptosis is an inflammation-related nucleotide-binding oligomerization segment-like receptor family 3 (NLRP3)-dependent pathway for programmed cell death. We previously reported that inappropriate inflammation caused by Cd is a major contributor to kidney injury. Therefore, research on Cd-induced inflammatory response and pyroptosis may clarify the mechanisms underlying Cd-induced nephrotoxicity. In this study, we observed that Cd-induced nephrotoxicity is associated with NLRP3 inflammasome activation, leading to an increase in proinflammatory cytokine expression and secretion, as well as pyroptosis-related gene upregulation, both in primary rat proximal tubular (rPT) cells and kidney tissue from Cd-treated rats. In vitro, these effects were significantly abrogated through siRNA-based Nlrp3 silencing; thus, Cd may trigger pyroptosis through an NLRP3 inflammasome-dependent pathway. Moreover, Cd exposure considerably elevated reactive oxygen species (ROS) content. N-acetyl-l-cysteine, an ROS scavenger, mitigated Cd-induced NLRP3 inflammasome activation and subsequent pyroptosis. Mechanistically, Cd hindered the expression and deacetylase activity of SIRT1, eventually leading to a decline in SIRT1-p65 interactions, followed by an elevation in acetylated p65 levels. The administration of resveratrol (a SIRT1 agonist) or overexpression of Sirt1 counteracted Cd-induced RELA/p65/NLRP3 pathway activation considerably, leading to pyroptosis. This is the first study to reveal significant contributions of SIRT1-triggered p65 deacetylation to pyroptosis and its protective effects against Cd-induced chronic kidney injury. Our results may aid in developing potential therapeutic strategies for preventing Cd-induced pyroptosis through SIRT1-mediated p65 deacetylation.

Toxic effect and mRNA mechanism of moon dust simulant induced pulmonary inflammation in rats

Moon dust presents a significant hazard to manned moon exploration missions, yet our understanding of its toxicity remains limited. The objective of this study is to investigate the pattern and mechanism of lung inflammation induced by subacute exposure to moon dust simulants (MDS) in rats. SD rats were exposed to MDS and silica dioxide through oral and nasal inhalation for 6 hours per day continuously for 15 days. Pathological analysis indicated that the toxicity of MDS was lower than that of silica dioxide. MDS led to a notable recruitment and infiltration of macrophages in the rat lungs. Material characterization and biochemical analysis revealed that SiO2, Fe2O3, and TiO2 could be crucial sources of MDS toxicity. The study revealed that MDS-induced oxidative stress response can lead to pulmonary inflammation, which potentially may progress to lung fibrosis. Transcriptome sequencing revealed that MDS suppresses the PI3K-AKT signaling pathway, triggers the Tnfr2 non-classical NF-kB pathway and IL-17 signaling pathway, ultimately causing lung inflammation and activating predominantly antioxidant immune responses. Moreover, the study identified the involvement of upregulated genes IL1b, csf2, and Sod2 in regulating immune responses in rat lungs, making them potential key targets for preventing pulmonary toxicity related to moon dust exposure. These findings are expected to aid in safeguarding astronauts against the hazardous effects of moon dust and offer fresh insights into the implications and mechanisms of moon dust toxicity.

LL-37 improves sepsis-induced acute lung injury by suppressing pyroptosis in alveolar epithelial cells

BACKGROUND

LL-37 (also known as murine CRAMP) is a human antimicrobial peptide that plays a crucial role in innate immune defence against sepsis through various mechanisms. However, its involvement in sepsis-induced lung injury remains unclear.

OBJECTIVES

This work investigates the impact of LL-37 on pyroptosis generated by LPS in alveolar epithelial cells. The research utilizes both in vivo and in vitro sepsis-associated acute lung injury (ALI) models to understand the underlying molecular pathways.

METHODS

In vivo, an acute lung injury model induced by sepsis was established by intratracheal administration of LPS in C57BL/6J mice, which were subsequently treated with low-dose CRAMP (recombinant murine cathelicidin, 2.5 mg.kg-1) and high-dose CRAMP (5.0 mg.kg-1). In vitro, pyroptosis was induced in a human alveolar epithelial cell line (A549) by stimulation with LPS and ATP. Treatment was carried out with recombinant human LL-37, or LL-37 was knocked out in A549 cells using small interfering RNA (siRNA). Subsequently, haematoxylin and eosin staining was performed to observe the histopathological changes in lung tissues in the control group and sepsis-induced lung injury group. TUNEL and PI staining were used to observe DNA fragmentation and pyroptosis in mouse lung tissues and cells in the different groups. An lactate dehydrogenase (LDH) assay was performed to measure the cell death rate. The expression levels of NLRP3, caspase1, caspase 1 p20, GSDMD, NT-GSDMD, and CRAMP were detected in mice and cells using Western blotting, qPCR, and immunohistochemistry. ELISA was used to assess the levels of interleukin (IL)-1β and IL-18 in mouse serum, bronchoalveolar lavage fluid (BALF) and lung tissue and cell culture supernatants.

RESULTS

The expression of NLRP3, caspase1 p20, NT-GSDMD, IL 18 and IL1β in the lung tissue of mice with septic lung injury was increased, which indicated activation of the canonical pyroptosis pathway and coincided with an increase in CRAMP expression. Treatment with recombinant CRAMP improved pyroptosis in mice with lung injury. In vitro, treatment with LPS and ATP upregulated these classic pyroptosis molecules, LL-37 knockdown exacerbated pyroptosis, and recombinant human LL-37 treatment alleviated pyroptosis in alveolar epithelial cells.

CONCLUSION

These findings indicate that LL-37 protects against septic lung injury by modulating the expression of classic pyroptotic pathway components, including NLRP3, caspase1, and GSDMD and downstream inflammatory factors in alveolar epithelial cells.

HMGB1/RAGE axis in tumor development: unraveling its significance

High mobility group protein 1 (HMGB1) plays a complex role in tumor biology. When released into the extracellular space, it binds to the receptor for advanced glycation end products (RAGE) located on the cell membrane, playing an important role in tumor development by regulating a number of biological processes and signal pathways. In this review, we outline the multifaceted functions of the HMGB1/RAGE axis, which encompasses tumor cell proliferation, apoptosis, autophagy, metastasis, and angiogenesis. This axis is instrumental in tumor progression, promoting tumor cell proliferation, autophagy, metastasis, and angiogenesis while inhibiting apoptosis, through pivotal signaling pathways, including MAPK, NF-κB, PI3K/AKT, ERK, and STAT3. Notably, small molecules, such as miRNA-218, ethyl pyruvate (EP), and glycyrrhizin exhibit the ability to inhibit the HMGB1/RAGE axis, restraining tumor development. Therefore, a deeper understanding of the mechanisms of the HMGB1/RAGE axis in tumors is of great importance, and the development of inhibitors targeting this axis warrants further exploration.

miR-328-3p targets TLR2 to ameliorate oxygen-glucose deprivation injury and neutrophil extracellular trap formation in HUVECs via inhibition of the NF-κB signaling pathway

BACKGROUND

Endothelial cell injury is one of the important pathogenic mechanisms in thrombotic diseases, and also neutrophils are involved. MicroRNAs (miRNAs) have been demonstrated to act as essential players in endothelial cell injury, but the potential molecular processes are unknown. In this study, we used cellular tests to ascertain the protective effect of miR-328-3p on human umbilical vein endothelial cells (HUVECs) treated with oxygen-glucose deprivation (OGD).

METHODS

In our study, an OGD-induced HUVECs model was established, and we constructed lentiviral vectors to establish stable HUVECs cell lines. miR-328-3p and Toll-like receptor 2 (TLR2) interacted, as demonstrated by the dual luciferase reporter assay. We used the CCK8, LDH release, and EdU assays to evaluate the proliferative capacity of each group of cells. To investigate the expression of TLR2, p-P65 NF-κB, P65 NF-κB, NLRP3, IL-1β, and IL-18, we employed Western blot and ELISA. Following OGD, each group's cell supernatants were gathered and co-cultured with neutrophils. An immunofluorescence assay and Transwell assay have been performed to determine whether miR-328-3p/TLR2 interferes with neutrophil migration and neutrophil extracellular traps (NETs) formation.

RESULTS

In OGD-treated HUVECs, the expression of miR-328-3p is downregulated. miR-328-3p directly targets TLR2, inhibits the NF-κB signaling pathway, and reverses the proliferative capacity of OGD-treated HUVECs, while inhibiting neutrophil migration and neutrophil extracellular trap formation.

CONCLUSIONS

miR-328-3p inhibits the NF-κB signaling pathway in OGD-treated HUVECs while inhibiting neutrophil migration and NETs formation, and ameliorating endothelial cell injury, which provides new ideas for the pathogenesis of thrombotic diseases.

New insights into micro-algal astaxanthin's effect on deoxynivalenol-induced spleen lymphocytes pyroptosis in Cyprinus carpio: Involving mitophagy and mtROS-NF-κB-dependent NLRP3 inflammasome

Deoxynivalenol (DON) is one of the most common sources of fungal toxins in fish feed, posing a significant risk to the immune and reproductive systems of fish. Microalgal astaxanthin (MIA), a potent antioxidant derived from microalgae, confers multifarious advantages upon piscine organisms, notably encompassing its anti-inflammatory and antioxidant prowess. Herein, we investigated the potential of MIA in ameliorating the immunotoxicity of DON on carp (Cyprinus carpio L.) based on spleen lymphocytes treated with DON (1.5 ng/ml) and/or MIA (96 μM). Firstly, CCK8 results showed that DON resulted in excessive death of spleen lymphocytes. Secondly, spleen lymphocytes treated with DON had a higher proportion of pyroptosis, and the mRNA and protein levels of pyroptosis (NLRP3, IL-1β and ASC) in spleen lymphocytes were increased. Thirdly, the relative red fluorescence intensity of JC-1 and DCFH-DA showed decreased mitochondrial membrane potential and increased ROS in spleen lymphocytes treated with DON. Mitochondrial ATP, DNA and NADPH/NADP+ analysis revealed decreased mitochondrial ATP, DNA and NADPH/NADP+ levels in DON-treated lymphocytes, corroborating the association between DON exposure and elevated intracellular ATP, DNA and NADPH/NADP+ in lymphocytes. DON exposure resulted in the downregulation of mitophagy-related genes and proteins (PINK1, Parkin and LC3) in lymphocytes. Notably, these effects were counteracted by treatment with MIA. Furthermore, DON led to the elevated secretion of inflammatory factors (TNF-α, IL-4 and IFN-γ), thereby inducing immune dysfunction in spleen lymphocytes. Encouragingly, MIA treatment effectively mitigated the immunotoxic effects induced by DON, demonstrating its potential in ameliorating pyroptosis, mitochondrial dysfunction and mitophagy impairment via regulating the mtROS-NF-κB axis in lymphocytes. This study sheds light on safeguarding farmed fish against agrobiological threats posed by DON, highlighting the valuable applications of MIA in aquaculture.

Toll-like Receptor 2-Melatonin Feedback Loop Regulates the Activation of Spinal NLRP3 Inflammasome in Morphine-Tolerant Rats

BACKGROUND AND PURPOSE

Morphine is amongst the most effective analgesics available for the management of severe pain. However, prolonged morphine treatment leads to analgesic tolerance which limits its clinical usage. Previous studies have demonstrated that melatonin ameliorates morphine tolerance by reducing neuroinflammation. However, little is known about the relationship between Toll like receptor 2 (TLR2) and neuroinflammation in morphine tolerance. The aim of this study was to explore the role of TLR2 in morphine tolerance and its connections with melatonin and Nod-like receptor protein 3 (NLRP3) inflammasome.

METHODS

Sprague-Dawley rats were treated with morphine for 7 days and tail-flick latency test was performed to identify the induction of analgesic tolerance. The roles of TLR2 in microglia activation and morphine tolerance were assessed pharmacologically, and the possible interactions between melatonin, TLR2 and NLRP3 inflammasome were investigated.

KEY RESULTS

Morphine tolerance was accompanied by increased TLR2 expression and NLRP3 inflammasome activation in spinal cord. whereas melatonin level was down-regulated. Chronic melatonin administration resulted in a reduced TLR2 expression and NLRP3 inflammasome activation. Moreover, the analgesic effect of morphine was partially restored. Inhibition of TLR2 suppressed the microglia and NLRP3 inflammasome activation, as well as restored the spinal melatonin level while attenuated the development of morphine tolerance. Furthermore, the inhibition of microglia activation ameliorated morphine tolerance via inhibiting TLR2-NLRP3 inflammasome signaling in spinal cord.

CONCLUSION

In this study, we directly demonstrate a TLR2-melatonin negative feedback loop regulating microglia and NLRP3 inflammasome activation during the development of morphine tolerance.

Environmental pollutants induce NLRP3 inflammasome activation and pyroptosis: Roles and mechanisms in various diseases

Environmental pollution is changing with economic development. Most environmental pollutants are characterized by stable chemical properties, strong migration, potential toxicity, and multiple exposure routes. Harmful substances are discharged excessively, and large quantities of unknown new compounds are emerging, being transmitted and amplifying in the food chain. The increasingly severe problems of environmental pollution have forced people to re-examine the relationship between environmental pollution and health. Pyroptosis and activation of the NLRP3 inflammasome are critical in maintaining the immune balance and regulating the inflammatory process. Numerous diseases caused by environmental pollutants are closely related to NLRP3 inflammasome activation and pyroptosis. We intend to systematically explain the steps and important events that are common in life but easily overlooked by which environmental pollutants activate the NLRP3 inflammasome and pyroptosis pathways. This comprehensive review also discusses the interaction network between environmental pollutants, the NLRP3 inflammasome, pyroptosis, and diseases. Thus, research progress on the impact of decreasing oxidative stress levels to inhibit the NLRP3 inflammasome and pyroptosis, thereby repairing homeostasis and reshaping health, is systematically examined. This review aims to deepen the understanding of the impact of environmental pollutants on life and health and provide a theoretical basis and potential programs for the development of corresponding treatment strategies.

Ozone-induced neurotoxicity: In vitro and in vivo evidence

Together with cities in higher-income nations, it is anticipated that the real global ozone is rising in densely populated areas of Asia and Africa. This review aims to discuss the possible neurotoxic pollutants and ozone-induced neurotoxicity: in vitro and in vivo, along with possible biomarkers to assess ozone-related oxidative stress. As a methodical and scientific strategy for hazard identification and risk characterization of human chemical exposures, toxicological risk assessment is increasingly being implemented. While traditional methods are followed by in vitro toxicology, cell culture techniques are being investigated in modern toxicology. In both human and rodent models, aging makes the olfactory circuitry vulnerable to spreading immunological responses from the periphery to the brain because it lacks the blood-brain barrier. The ozone toxicity is elusive as it shows ventral and dorsal root injury cases even in the milder dose. Its potential toxicity should be disclosed to understand further the clear mechanism insights of how it acts in cellular aspects. Human epidemiological research has confirmed the conclusions that prenatal and postnatal exposure to high levels of air pollution are linked to behavioral alterations in offspring. O3 also enhances blood circulation. It has antibacterial action, which may have an impact on the gut microbiota. It also activates immunological, anti-inflammatory, proteasome, and growth factor signaling Prolonged O3 exposure causes oxidative damage to plasma proteins and lipids and damages the structural and functional integrity of the mitochondria. Finally, various studies need to be conducted to identify the potential biomarkers associated with ozone and the brain.

Non-apoptotic programmed cell deaths in diabetic pulmonary dysfunction: the new side of advanced glycation end products

Diabetes mellitus (DM) is a chronic metabolic disorder that affects multiple organs and systems, including the pulmonary system. Pulmonary dysfunction in DM patients has been observed and studied for years, but the underlying mechanisms have not been fully understood. In addition to traditional mechanisms such as the production and accumulation of advanced glycation end products (AGEs), angiopathy, tissue glycation, oxidative stress, and systemic inflammation, recent studies have focused on programmed cell deaths (PCDs), especially the non-apoptotic ones, in diabetic pulmonary dysfunction. Non-apoptotic PCDs (NAPCDs) including autophagic cell death, necroptosis, pyroptosis, ferroptosis, and copper-induced cell death have been found to have certain correlations with diabetes and relevant complications. The AGE-AGE receptor (RAGE) axis not only plays an important role in the traditional pathogenesis of diabetes lung disease but also plays an important role in non-apoptotic cell death. In this review, we summarize novel studies about the roles of non-apoptotic PCDs in diabetic pulmonary dysfunction and focus on their interactions with the AGE-RAGE axis.

Role of NLRP3 in the exacerbation of ozone-induced allergic rhinitis

OBJECTIVE

Allergic rhinitis (AR) is an immunoglobulin E (IgE)-mediated inflammatory disorder of the nasal mucosa, and the impact of ozone on AR is gaining increasing attention. Although NOD-like receptor thermal protein domain associated protein 3 (NLRP3) plays a crucial role in the pathogenesis of AR, its regulatory mechanisms in ozone-induced exacerbation remain unclear. Therefore, we explored the impact of ozone inhalation on inflammation in AR and investigated the regulatory mechanisms involving NLRP3.

METHODS

Fifty female Sprague-Dawley rats were selected and divided into five groups: normal control (NC), normal with ozone exposure (NE), AR model, AR with ozone exposure (ARE), and ARE treated with the NLRP3 inhibitor MCC950 (ARE+MCC950). Behavioral changes were observed in the rats, and the expression of NLRP3, active-caspase 1, and GSDMD-N was detected by western blotting. The expression levels of interleukin (IL)- 4, IL-5, IL-13, IL-1β, and ovalbumin-specific IgE (OVA-sIgE) in nasal lavage fluid as well as IL-6 in the serum were measured by ELISA. The expression and distribution of NLRP3 and IL-1β in nasal mucosal tissue were detected by immunohistochemistry, and pathological changes and eosinophilic infiltration in nasal mucosal tissue were observed by hematoxylin and eosin (HE) staining. The effects of ozone exposure on inflammation in the nasal mucosal tissue of rats with AR and the relationship between NLRP3 and inflammation were analyzed.

RESULTS

Upregulation of NLRP3 was observed in the AR rat model, and ozone further aggravated the expression of NLRP3 in the nasal mucosal tissue. Compared to the AR, NC, and NE groups, NLRP3 inflammasomes were activated in the ARE group, and the expression levels of related indexes active-caspase 1 and GSDMD-N were significantly increased; the expression levels of Th2 inflammatory factors IL-4, IL-5, IL-13, and OVA-sIgE were increased, and inflammatory factors such as IL-1β and IL-6 expression was also significantly increased. HE staining revealed that ozone aggravated damage to the nasal mucosal tissue in AR. Compared with the ARE group, the expression of NLRP3 inflammasomes was downregulated, sneezing and scratching symptoms were reduced, inflammatory indicators in nasal lavage fluid were decreased, and nasal mucosal tissue damage was alleviated in rats in the ARE+MCC950 group.

CONCLUSION

Ozone exposure significantly increased the inflammatory response in an animal model of AR. MCC950 can selectively inhibit the expression of NLRP3, inhibit the activity of inflammasomes, and reduce nasal mucosal inflammation by regulating the NLRP3-caspase-1-IL-1β pathway.

Pollutant-induced pyroptosis in humans and other animals

Pyroptosis is a form of lytic cell death with pro-inflammatory characteristics, induced upon the activation of certain inflammatory caspases by inflammasome complexes such as NLRP3 inflammasome. Gasdermin proteins as the mediators of pyroptosis form cell membrane pores upon activation, which release certain cellular contents into the extracellular space including inflammatory cytokines such as IL-1β and IL-18, and also damage the integrity of the cell membrane. Gasdermins have been implicated in autoimmune and inflammatory diseases, infectious diseases, deafness and cancer. Mostly in the last 2 years, diverse pollutant types including particulate matter, cadmium and polystyrene microplastics were reported to induce pyroptotic cell death in diverse tissues from mammals to birds. In the present study, we review our current understanding of pollutant-induced pyroptosis as well as current knowledge of upstream events leading to pyroptotic cell death upon exposure to pollutants.

Advances in understanding mechanisms underlying mitochondrial structure and function damage by ozone

Mitochondria are double-membraned organelles found in eukaryotic cells. The integrity of mitochondrial structure and function determines cell destiny. Mitochondria are also the "energy factories of cells." The production of energy is accompanied by reactive oxygen species (ROS) generation. Generally, the production and consumption of ROS maintains a balance in cells. Ozone is a highly oxidizing, harmful substance in ground-level atmosphere. Ozone inhalation causes oxidative injury owing to the generation of ROS, resulting in mitochondrial oxidative stress overload. Oxidative damage to the mitochondria induces a vicious cycle of ROS production which might destroy mitochondrial DNA and mitochondrial structure and function in cells. ROS can alter the phosphorylation of various signaling molecules, triggering a series of downstream signaling pathway reactions. These include inflammatory responses, pyroptosis, autophagy, and apoptosis. Changes involving these molecular mechanisms may be related to the occurrence of disease. According to numerous epidemiological investigations, ozone exposure induces respiratory, cardiovascular, and nervous system diseases in humans. In addition, these systems require large quantities of energy. Hence, the mitochondrial damage caused by ozone may act as a bridge between human diseases. However, the specific molecular mechanisms involved require further investigation. This review discusses our understanding of the structure and function of mitochondria the mechanisms underlying ozone-induced mitochondrial damage.

Impact of chronic cold exposure on lung inflammation, pyroptosis and oxidative stress in mice

Chronic cold exposure, which is the main inducer of lung diseases in high latitudes, affects production efficiency and restricts the development of aquaculture. Although the relationship between cold exposure and susceptibility to the lungs is widely accepted, but the influence between them has not been fully explored. The aim of this study is to understand the underlying mechanism. In the present study, the mice, which are used to establish cold stress (CS)-induced lung injury model, are exposed to cold temperature (4 °C) for 3 h each day for 4 weeks. The results indicate that the expression of heat shock protein 70 (HSP70) is augmented by cold exposure. In addition, chronic cold exposure aggravate the formation of malondialdehyde (MDA) and lead to a significant decrease in the contents of micrococcus catalase (CAT) and glutathione (GSH). Moreover, chronic cold exposure significantly exacerbates the expression of inflammation- and apoptosis-related proteins. The activation of Bax and caspase-3 are significantly augmented. However, that of Bcl-2 is decreased. These results are different from those in room team. The results show that chronic cold exposure plays an important roles in the activation of multiple signaling pathways, such as pyroptosis-related, inflammation-related and oxidative stress-regulated signaling pathways. In summary, these investigations support that chronic cold exposure increase the risk of lung injury by activating inflammation, oxidative stress and pyroptosis.

Polystyrene microplastics induced inflammation with activating the TLR2 signal by excessive accumulation of ROS in hepatopancreas of carp (Cyprinus carpio)

Polystyrene microplastics (PS-MPs) affect the immune defense function on carp (Cyprinus carpio). The PS-MPs model of carp was established by feeding with PS-MPs particle size of 8 µm and concentration of 1000 ng/L water. Hepatopancreas function test revealed the activities of AKP, ALT, AST and LDH abnormal increase. PS-MPs induced tissue damage and lead to abnormal hepatopancreas function. The PS-MPs also induced a oxidative stress with the antioxidant enzymes SOD, CAT, GSH-PX, and T-AOC activities decreasing and reactive oxygen species (ROS) excessive accumulation. PS-MPs activated the Toll like receptor-2 (TLR2) signaling pathway. The mRNA and protein expressions of TLR2, Myeloid differentiation primary response 88 (MyD88), tumor necrosis factor receptor-associated factor 6 (TRAF6), NF-κB p65, Tumor necrosis factor (TNF-α), Interleukin-1β (IL-1β), Inducible Nitric Oxide Synthase (iNOS), and cycooxygenase 2(COX2) was revealed increased in both hepatopancreas and hepatocytes with the qPCR and Western blotting analysis mode. ELISA showed the expressions of TNF-α, IL-1β, iNOS, and COX2 inflammatory molecule were increased in both hepatopancreas and hepatocytes. The results showed that PS-MPs caused a serious injure in the hepatopancreas and brought serious effects on the inflammatory response of carp. The present study displayed the harm caused by PS-MPs in freshwater fish, and provided some suggestions and references for toxicological studies of microplastics in freshwater environment.

NLRP3-mediated pyroptosis in diabetic nephropathy

Diabetic nephropathy (DN) is the main cause of end-stage renal disease (ESRD), which is characterized by a series of abnormal changes such as glomerulosclerosis, podocyte loss, renal tubular atrophy and excessive deposition of extracellular matrix. Simultaneously, the occurrence of inflammatory reaction can promote the aggravation of DN-induced kidney injury. The most important processes in the canonical inflammasome pathway are inflammasome activation and membrane pore formation mediated by gasdermin family. Converging studies shows that pyroptosis can occur in renal intrinsic cells and participate in the development of DN, and its activation mechanism involves a variety of signaling pathways. Meanwhile, the activation of the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome can not only lead to the occurrence of inflammatory response, but also induce pyroptosis. In addition, a number of drugs targeting pyroptosis-associated proteins have been shown to have potential for treating DN. Consequently, the pathogenesis of pyroptosis and several possible activation pathways of NLRP3 inflammasome were reviewed, and the potential drugs used to treat pyroptosis in DN were summarized in this review. Although relevant studies are still not thorough and comprehensive, these findings still have certain reference value for the understanding, treatment and prognosis of DN.

ALPK1 Accelerates the Pathogenesis of Osteoarthritis by Activating NLRP3 Signaling

Alpha-kinase 1 (ALPK1), a member of the alpha-kinase family, has been shown to be involved in mediating inflammatory responses and is strongly associated with gout; however, its modulatory role in osteoarthritis (OA) remains unclear. Here, we uncovered elevation of ALPK1 in degraded cartilage of destabilized medial meniscus (DMM) and collagenase-induced osteoarthritis (CIOA), two different mouse OA models induced by mechanical stress or synovitis. Intraarticular administration of recombinant human ALPK1 (rhALPK1) in vivo exacerbated OA pathogenesis in both DMM and CIOA mice, whereas ALPK1 knockout reversed this process. In vitro study demonstrated that ALPK1 aggravates metabolic disturbances in chondrocytes by enhancing the production of NOD-like receptor protein 3 (NLRP3), an inflammasome sensors driving interlukin-1β (IL-1β)-mediated inflammatory conditions. Furthermore, the selective inhibition of nuclear factor-κB (NF-κB) or NLRP3 indicates that NLRP3 is a downstream signaling governed by NF-κB in ALPK1-activated chondrocytes. Collectively, these results establish ALPK1 as a novel catabolic regulator of OA pathogenesis, and targeting this signaling may be a promising treatment strategy for OA. © 2022 American Society for Bone and Mineral Research (ASBMR).

Ambient ozone, and urban PM2.5 co-exposure, aggravate allergic asthma via transient receptor potential vanilloid 1-mediated neurogenic inflammation

Allergic asthma is the most common pulmonary inflammatory disease, and epidemiological studies have revealed that PM_2.5 or ambient ozone (O₃) exposure contribute to the higher prevalence of allergic asthma. Current experimental evidence focus principally on the pathogenic effect of exposure to a single air pollutant, ignoring the possible synergistic effect of combined exposure to a mix of these pollutants, which is a more realistic scenario. In this study, allergic mice and a nociceptor antagonist were used to explore the mechanisms of co-exposure to these two important air pollutants. Compared with exposure to either PM_2.5 or O₃, combined exposure to both greatly aggravated allergic asthma in a dose dependent manner, including increased airway hyperresponsiveness, goblet cell metaplasia, more severe airway inflammation and higher oxidative stress levels. In addition, co-exposure in the allergic mice resulted in elevation of the expression of transient receptor potential vanilloid 1 (TRPV1), and of the production of substance P (SP), which exacerbated lung inflammation by neurogenic inflammation. TRPV1 antagonist (capsazepine, CPZ) treatment for the co-exposed allergic mice, markedly attenuated TRPV1 expression and SP release, and reduced airway inflammation and oxidative damage, further alleviating airway hyperresponsiveness. We conclude that neuro-immune interactions might be involved in PM_2.5 and O₃ co-exposure aggravated allergic asthma.

Ambient ozone exposure induces ROS related-mitophagy and pyroptosis via NLRP3 inflammasome activation in rat lung cells

OBJECTIVE

To study the regulatory relationship between ozone-induced mitophagy and pyroptosis in lung epithelial cells.

RESULTS

First, type I primary alveolar epithelial cells and male Wistar rats were treated with ozone at different dosages. The ATP content and mitochondrial membrane potential significantly decreased in type I primary alveolar epithelial cells. The mitophagy-related markers and PINK1/Parkin pathway-related proteins, and the co-localization of LC3, Parkin, and mitochondria in type I alveolar epithelial cells indicated that ozone exposure triggered mitophagy. On the other hand, the reactive oxygen species (ROS) inhibitor NAC could significantly alleviate mitophagy in epithelial cells. After treatment with the mitophagy inhibitor MDIVI-1, the levels of the NLRP3 inflammasome, cleaved caspase-1, and N-gasdermin D (N-GSDMD) significantly decreased in the cells. Altogether, these results indicated that mitophagy can be triggered by ozone exposure, and subsequently induces cell death mediated by the NLRP3 inflammasome. Finally, the overexpression and knockdown of NLRP3 confirmed this conclusion.

CONCLUSION

Ozone exposure induced oxidative damage, leading to mitochondrial structural and functional damage. Ozone-induced ROS triggered mitophagy through the activation of the PINK1/Parkin signaling pathway, then pyroptosis through activation of the NLRP3 inflammasome.

Association of the RAGE/RAGE-ligand axis with interstitial lung disease and its acute exacerbation

The receptor for advanced glycation end product (RAGE) is a transmembrane receptor highly expressed in type 1 pneumocytes of healthy lungs. RAGE is considered to play a homeostatic role in the lung, as RAGE knockout mice develop lung fibrosis as they age. In contrast, RAGE can bind numerous ligands, including high-mobility group box 1 (HMGB1). These interactions initiate pro-inflammatory signaling associated with the pathogenesis of lung injury and interstitial lung disease (ILD), including idiopathic pulmonary fibrosis (IPF). ILD is a broad category of diffuse parenchymal lung disease characterized by various extents of lung fibrosis and inflammation, and IPF is a common and progressive ILD of unknown cause. The prognosis of patients with IPF is poor, and acute exacerbation of IPF (AE-IPF) is one of the main causes of death. Recent reports indicate that acute exacerbations can occur in other ILDs (AE-ILD). Notably, ILD is frequently observed in patients with lung cancer, and AE-ILD after surgical procedures or the initiation of chemotherapy for concomitant lung cancer are clinically important due to their association with increased mortality. In this review, we summarize the associations of RAGE/soluble RAGE (sRAGE)/RAGE ligands with the pathogenesis and clinical course of ILD, including IPF and AE-IPF. Additionally, the potential use of sRAGE and RAGE ligands as predictive markers of AE-IPF and cancer treatment-triggered AE-ILD is also discussed.

Metadherin silencing results in the inhibition of pyroptosis in lipopolysaccharide/adenosine triphosphate - stimulated renal tubular epithelial cells

Pyroptosis is induced following inflammation via activation of the NLRP3 inflammasome. Lipopolysaccharide (LPS)-induced acute inflammation causes pyroptosis in renal tubular epithelial cells, which aggravates kidney damage and is involved in physiopathological processes in multiple renal diseases. Metadherin (Mtdh) induces inflammation by NLRP3 inflammasome activation. Specifically, it induces inflammatory injury in the kidney by activating the nuclear factor kappa B (NF-κB) signaling pathway, which is involved in NLRP3 inflammasome activation. However, the role of Mtdh in pyroptosis in renal tubular epithelial cells is unclear. Therefore, we investigated whether Mtdh participates in pyroptosis in LPS/adenosine triphosphate (ATP)-treated NRK-52E cells by activating the NLRP3 inflammasome and NF-κB signaling pathway. We induced pyroptosis in NRK-52E cells with LPS/ATP, after which Mtdh was silenced via transfection with small interfering RNA. LPS/ATP upregulated Mtdh expression and induced pyroptosis and NLRP3 inflammasome activation in NRK-52E cells. However, downregulation of Mtdh expression resulted in the alleviation of pyroptosis in LPS/ATP-treated NRK-52E cells. Additionally, activation of the NLRP3 inflammasome and NF-κB signaling pathway was inhibited. This demonstrates that downregulation of Mtdh expression results in the inhibition of pyroptosis in LPS/ATP-treated NRK-52E cells through the suppression of NLRP3 inflammasome activation, which occurs via inhibition of the NF-κB signaling pathway.

Ozone treatment alleviates brain injury in cerebral ischemic rats by inhibiting the NF-κB signaling pathway and autophagy

Stroke is the most frequent cause of disability in developed countries. A common phenomenon of stroke, cerebral ischemia, is threatening many lives worldwide. In addition, ozone treatment was previously reported to exert functions in relieving brain injury. In the current study, the therapeutic effects of ozone on cerebral ischemia are investigated. A rat model of middle cerebral artery occlusion (MCAO) was established. The brain water content was calculated by weighing brain tissues, and the 2, 3, 5-triphenyltetrazolium chloride staining was performed to measure brain infarction volume in rats. A colorimetric assay was conducted to examine expression levels of malondialdehyde, superoxide dismutase, catalase, and glutathione in the rat hippocampus. Reverse transcription quantitative polymerase-chain reaction and Western blot analyses were employed to evaluate expression levels of Beclin1, LC3B, p62, and critical factors implicated in the NF-κB signaling pathway. We found that ozone significantly improved the survival rate of MCAO model rats, reduced the cerebral water content, and decreased the neurological scores of ischemic rats. Ozone markedly reduced cerebral ischemia-induced infarction in ischemic rats. Ozone decreased MDA levels and increased SOD, catalase, and GSH levels in the hippocampus of rats. Ozone significantly inhibited autophagy by decreasing Beclin1 and LC3B expression and increasing p62 expression. The ozone inactivated the NF-κB signaling pathway by decreasing the protein levels of TLR4, p-IKKβ, p-IKBα, and p-p65. We conclude that ozone treatment alleviates the brain injury in ischemic rats by suppressing autophagy and inactivating the NF-κB signaling pathway.

Pyrroloquinoline quinone ameliorates diabetic cardiomyopathy by inhibiting the pyroptosis signaling pathway in C57BL/6 mice and AC16 cells

Purpose

Diabetic cardiomyopathy (DCM), a common complication of diabetes mellitus and is characterized by myocardial hypertrophy and myocardial fibrosis. Pyrroloquinoline quinone (PQQ), a natural nutrient, exerts strong protection against various myocardial diseases. Pyroptosis, a type of inflammation-related programmed cell death, is vital to the development of DCM. However, the protective effects of PQQ against DCM and the associated mechanisms are not clear. This study aimed to investigate whether PQQ protected against DCM and to determine the underlying molecular mechanism.

Methods

Diabetes was induced in mice by intraperitoneal injection of streptozotocin, after which the mice were administered PQQ orally (10, 20, or 40 mg/kg body weight/day) for 12 weeks. AC16 human myocardial cells were divided into the following groups and treated accordingly: control (5.5 mmol/L glucose), high glucose (35 mmol/L glucose), and HG + PQQ groups (1 and 10 nmol/L PQQ). Cells were treated for 24 h.

Results

PQQ reduced myocardial hypertrophy and the area of myocardial fibrosis, which was accompanied by an increase in antioxidant function and a decrease in inflammatory cytokine levels. Moreover, myocardial hypertrophy—(ANP and BNP), myocardial fibrosis—(collagen I and TGF-β1), and pyroptosis-related protein levels decreased in the PQQ treatment groups. Furthermore, PQQ abolished mitochondrial dysfunction and the activation of NF-κB/IκB, and decreased NLRP3 inflammation-mediated pyroptosis in AC16 cells under high-glucose conditions.

Conclusion

PQQ improved DCM in diabetic mice by inhibiting NF-κB/NLRP3 inflammasome-mediated cell pyroptosis. Long-term dietary supplementation with PQQ may be greatly beneficial for the treatment of DCM.

Graphical abstract

Diagram of the underlying mechanism of the effects of PQQ on DCM. PQQ inhibits ROS generation and NF-κB activation, which stimulates activation of the NLRP3 inflammasome and regulates the expression of caspase-1, IL-1β, and IL-18. The up-regulated inflammatory cytokines trigger myocardial hypertrophy and cardiac fibrosis and promote the pathological process of DCM.

MiR-200c-3p regulates pyroptosis by targeting SLC30A7 in diabetic retinopathy

CLINICAL RELEVANCE

MicroRNAs (miRNAs) have been reported to be involved in the progression of various diseases. Studying the regulatory mechanisms of miRNAs can help clinical treatment.

BACKGROUND

Diabetic retinopathy (DR) is one of the complications of diabetes. The objective of this study was to elucidate the underlying molecular mechanisms by which miR-200c-3p regulates the pyroptosis of DR cell.

METHODS

Human retinal microvascular endothelial cells (HRMECs) and high glucose (HG) cultures established DR cell model in vitro. RT-qPCR is used to detect the expression level of miRNAs. CCK-8 assays and flow cytometry are used to detect apoptosis of HRMECs cell. Western blotting is used to detect cleaved caspase-3, cleaved caspase-1, and N-GSDMD proteins levels in HRMECs. The ELISA assay is used to detect the expression of IL-1β and IL-18. Predict and validate potential binding sites between miR-200c-3p and SLC30A7 by dual luciferase reporter gene analysis.

RESULTS

The results showed that HG caused damage to HRMECs through the pyroptosis pathway rather than the apoptosis pathway. MiR-200c-3p is highly expressed in HG induced-HRMECs, and knockdown of miR-200c-3p mitigates HG-induced HRMECs pyroptosis. MiR-200c-3p negatively targets SLC30A7 in HRMECs, and miR-200c-3p regulates pyroptosis of HG-induced HRMECs by targeting SLC30A7.

CONCLUSION

The results suggest that miR-200c-3p might be a promising interference target for DR prevention and treatment. The results of current study may provide new insights into development of therapeutic strategies for DR.

N-acetylcysteine alleviates pulmonary inflammatory response during benzo[a]pyrene-evoked acute lung injury

Benzo[a]pyrene (BaP), a representative polycyclic aromatic hydrocarbon, exists widely in automobile emissions and polluted atmosphere. The current study aimed to describe pulmonary inflammation during BaP-induced acute lung injury (ALI). All mice except controls were intratracheally instilled with a single dose of BaP (90 μg per mouse). The alveolar structure was damaged, accompanied by numerous inflammatory cell infiltration around pulmonary interstitium and small airway. Airway wall area and mean linear intercept were reduced in BaP-exposed mouse lungs. By contrast, airway wall thickness and destructive index were elevated in BaP-exposed mouse lungs. Several inflammatory genes, such as Tnf-α, Il-1β, Il-6, Mip-2, Kc, and Mcp-1, were upregulated in mouse lungs. Phosphorylated IκBα was elevated in BaP-exposed mouse lungs. Nuclear translocation of NF-κB p65 and p50 was accordingly observed in BaP-exposed mouse lungs. Several molecules of the MAPK pathway, including JNK, ERK1/2, and p38, were activated in mouse lungs. Of interest, pretreatment with N-acetylcysteine (NAC), an antioxidant, alleviated BaP-induced ALI. Moreover, NAC attenuated BaP-induced inflammatory cell infiltration in mouse lungs and inflammatory gene upregulation in A549 cells. In addition, NAC attenuated BaP-induced NF-κB activation in A549 cells and mouse lungs. These results suggest that NAC alleviates pulmonary inflammatory response during BaP-evoked ALI.

The CXCL1-CXCR2 Axis Mediates Tubular Injury in Diabetic Nephropathy Through the Regulation of the Inflammatory Response

Diabetic nephropathy (DN) is one of the most severe complications of diabetes. Inflammation mediated by inflammatory factors is thought to accelerate the progression of renal damage in DN. However, which inflammatory factors mediate the inflammatory response in DN remains unclear. In this study, we determined that the CXCL1-mediated inflammatory response may play an essential role in DN progression through bioassays. Subsequently, we observed that the expression of CXCL1 and its receptor (CXCR2) was significantly increased in the kidneys of mice with HFD + STZ induced diabetes and DN patients. In addition, inhibition of the CXCL1/CXCR2 axis by repertaxin alleviates renal inflammation and pathological damage in the kidneys of db/db mice. Finally, we noted that the CXCL1/CXCR2 axis might lead to inflammatory damage through phosphorylated NF-κB and further activate the NLRP3 inflammasome. Our results revealed the role of the CXCL1/CXCR2 axis in DN progression for the first time, which may be a novel therapeutic target for DN.

New Insights into the Role of NLRP3 Inflammasome in Pathogenesis and Treatment of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is an inflammatory lung disease characterized by chronic airway obstruction and emphysema. Accumulating studies have shown that the onset and development of COPD are related to an aberrant immune response induced by the dysregulation of a number of genetic and environmental factors, while the exact pathogenesis of this disease is not well defined. Emerging studies based on tests on samples from COPD patients, animal models, pharmacological and genetic data suggest that the NLR family pyrin domain containing 3 (NLRP3) inflammasome activation is required in the lung inflammatory responses in the development of COPD. Although the available clinical studies targeting the inflammasome effector cytokine, IL-1β, or IL-1 signaling do not show positive outcomes for COPD treatment, many alternative strategies have been proposed by recent emerging studies. Here, we highlight the recent progress in our understanding of the role of the NLRP3 inflammasome in COPD and propose possible future studies that may further elucidate the roles of the inflammasome in the pathogenesis or the intervention of this inflammatory lung disease.